US2952580A

US2952580A - Process for the modification of fibrous materials

Info

Publication number: US2952580A
Application number: US485313A
Authority: US
Inventors: Herbert Manfred Freud D Frasch
Original assignee: Individual
Current assignee: Individual
Priority date: 1954-02-02
Filing date: 1955-01-31
Publication date: 1960-09-13
Anticipated expiration: 1977-09-13
Also published as: NL194436A; FR1099015A; DE1027050B; NL113652C; GB780513A; FR1114001A

Description

United States Patent ()fiice 2,952,580 Patented Sept. 13, 1960 PROCESS FOR THE MODIFICATION OF FIBROUS MATERIALS Herbert Manfred Freud dit Jean Frasch, 5 Boulevard du Sud-Est, Nanterre, Seine, France No Drawing. Filed Jan. 31, 1955, Ser. No. 485,313 Claims priority, application France Feb. 2, 1954 20 Claims. (Cl. 162-158) Among the com-;

to the greatest-extentin order'to'lower th'epriceof'th paper.

It should be noted that in this industry the margin of profit is extremely small and that the least reduction in expense, or economy of manufacture is transformed by reason of the large tonnage by which the products are manufactured, into considerable sums of money.

Among the other and newer type of fillers is titanium dioxide (T102) which is used despite the extremely high price thereof in order to impart to the paper an extremely high whiteness and opacity.

The principle of action of such powdered materials such as titanium dioxide is to fill the spaces between the fibers in such manner as to be better distributed by the pressure exerted by the rollers and to improve the homogeneity of the paper. This filling of the spaces between the fibers is also of importance in the utilization of products having a high index of refraction such as titanium dioxide in order to improve the opacity of the paper, the opacity being a function of the difference of the indices of refraction between two mediums. V V

In place of having a difference of index of refraction of 0.5 between cellulose and air (the index of refraction n for cellulose being 1.51 and for air being 1) a difference in index of refraction of 1.1 is obtained in the case of utilizing titanium dioxide (n for cellulose being 1.51 and for titanium dioxide being 2.6).

Mainly fillers are introduced into the paper in order to obtain the higher opacity of the fillers. But it has been found that the introduction of a high proportion of such fillers in the paper diminishes the mechanical properties which therefore necessitates the utilization of a thicker paper, which in itself is already more'opaque.

On the other hand it is known that because of the slight afiinity of the various powdered fillers for the cellulose, the retention of these fillers by the fibers locates only about 50% of the fillers therebetween which on the one hand has the effect of loss of a great part of a rather precious product and on the other hand has the effect of clogging the web and scratching the rollers by reason of the particular minerals which are in suspension in the waters utilized in the paper industry.

It is therefore a primary object of the present invention to provide a means for eliminating the above disadvantages of the prior art while still conferring to the paper a whiteness and opacity comparable to papers treated according to the known procedures but at a price which is greatly lowered.

It is another object of the present invention to provide new products with which paper and similar products may be treated to increase the whiteness and opacity of the paper at substantially reduced cost.

It is still another object of the present invention to provide a method of loading paper without the need for using powdered fillers.

It is yet another object of the present invention to provide a method of flocculating a filler material in the interior of the fiber of the paper so as to increase the whiteness andopacity thereof.

It is a further object of the present invention to provide a method of treating paper and the like materials which not only increases the whiteness and opacity of the paper but which does so without decreasing and in fact with increasing the mechanical strength of the paper.

, It is still afurther object of the present invention to provide a method of increasing the whiteness and opacity of P per wh rghy at the sametime the mechanicalr strengthbfthe paper is increased and the paper is made resistant to microorganisms which are known to destroy paper.

It is yet a further object of the present invention to provide a complex cerium oxide, titanium oxide and zirconium oxide in acid solution from which may be precipitated the corresponding metal compound onto or within the fibers of paper or the like for whitening and increasing the opacity of the paper.

The present invention also contemplates as an object thereof the production of relatively stable solution of cerium titanium and zirconium acid complexes.

As another object the present invention contemplates methods of production of complex ceryl, titanyl and zirconyl-acid solutionsforthe-treatment of paper and the like.

It is also an object of the present invention to provide relatively stable complex ceryl, titanyl and zirconylacid-gelatin solutions from which compounds may be precipitated onto or within the fibers of paper orthe like for whitening and increasing the opacity of the paper.

The present invention also contemplates as an object thereof the production of relatively stable solutions of cerium, titanium and. zirconium-acid-gelatin complexes.

It is still another object of the present invention to provide dispersions of powdered filler materials such as titanium dioxide in the solutions of the present invention for the loading of paper and the like therewith as well as with the compounds precipitated from the solutions of the present invention.

It is a further object of the present invention to provide methods of precipitating the filler materials of the present invention from the solutions of the present invention onto, between or in the fibers of the paper or the like.

Other objects and advantages of the present invention will be apparent from a further reading of the specification and of theappended claims.

With the above objects in view the present invention mainly consists in a method of improving the characteristics of a fibrous cellulose product, comprising the steps of applying to a fibrous cellulose stock an aqueous solution having a pH -7 of at least one water-soluble complex of monovalent radical-metal oxide-organic acid radical salts, the monovalent radical being selected from the group consisting of alkali metals and ammonium, the metal oxide being selected from the group consisting of ZrO TiO and CeO and the organic acid radical being selected from the group consisting of citric acid, malic acid, tartaric acid, and lactic acid, the molecular ratio of the organic acid radical to the metal oxide being between 1:2 and 1:6, and precipitating a substance including the metal oxide from the applied solution while the fibrous cellulose stock is in contact therewith, whereby the precipitated substance is retained by the fibrous cellulose stock, increasing the whiteness and opacity thereof.

According'to a preferred embodiment of the present invention thecomplex is a complex of sodium-Z1 0 citrate salts, in which case the molecular ratio of citrate to ZrO is preferably between 1:2..5 and 1:4.

According to another embodiment of the present invention the complex may be a complex of sodium-TiO citrate salts in which case the molecular ratio of citrate to TiO is most preferably between 1:4.5 and 1:6. In general the solutions according to the present invention contain between 26% by weight of the metal oxide, e.g. ZrO Ti0 or (3e0 although. wide variations as to the concentration of the metal oxide in the solution are permissible, because solutions having these concentrations are easy to form and give very good results.

The solution may be applied to the fibrous cellulose stock by adding the solution to the paper-making waters, e.g. by addition of the solution to the beater or tub before or after the introduction of the fibrous stock. The flocculation or precipitation of the complex including the metal oxide in the paper pulp may then be accomplished by lowering the pH of the solution sufiiciently to cause the flocculation, preferably by the addition of a polyvalent cation such as aluminum or thorium in the form of aluminum sulfate or thorium sulfate, for example. The exact quantity of cation necessary to cause this floccula aennepends oh' niimerous variables such a s the initial pH of the impure waters, the quantity of complex incorporated in the solution, etc. However, anyone skilled in the art could easily determine the exact amount required for precipitation of the complex by the polyvalent cation by simple pre-testing.

It is a great advantage of the present invention that by the precipitation of the complex in contact with the fibrous cellulose stock, e.g. the paper pulp, what is obtained is not merely an incorporation of a mineral charge in the form of a powder in the interstices of the paper, it actually causes a flocculation in the interior of the fibers of thet paper of the white metal oxide such as TiO which greatly increases the opacity and the index of refraction of the fiber itself and therefore of the final product. This results in a much superior increase in the whitening and opacity of the final product with much less of the metal oxide, as will be more clearly apparent from the further description, then could possibly be obtained by the known processes.

Additional advantageous results are obtained in ac cordance with the present invention, according to a preferred embodiment thereof, by distributing the usual powdered filler, such as titanium dioxide, zinc sulfide, and the like in the solution of the complex, this powdered filler acting as adjunct to the complex in the solution and the filler filling the interstices between the fibers while the complex upon precipitation thereof is embedded in the fibers themselves. However, according to this embodiment the amount of filler distributed in the solution plus the amount of metal oxide itself in the solution in the form of a complex is always substantially less than the amount of powdered filler necessary according to the prior processes without the use of the complex while achieving at least the equivalent results of the prior processes. This, therefore, results in a considerable the presence of a polyvalent cation furnished by a salt l saving in the filler material which is of great importance economically in the paper industry.

The complexes of the present invention may be formed with an orgnaic acid containing free hydroxyl groups such as citric acid, malic acid, tartaric acid, or lactic acid. Citric acid is preferred. It should be noted, that the present invention resides in the use of relatively stable complexes as previously described which can be introduced into the waters of the paper industry in the form of solutions and intimately mixed with the pulp without flocculation, the flocculation resulting in a subsequent step by means of a slight variation of the pH and such as aluminum sulfate or thorium sulfate.

The simple soluble salts of titanium, zirconium, titanyl,

zirconyl such as the sulfates, chlorides and the like, cannot be utilized because they cannot be brought to a pH of 5-7 since they already start to flocculate at a pH of about 2.

On the other hand, certain complex radical-oxides are known in which the molecular ratio of acid radical to oxide is in the order of 2:1 to 6:1, that is, the inverse of the molecular ratios according to the present invention. I have determined, however, that these complexes are too stable and cannot be properly flocculated, e.g. by

means of aluminum sulfate so that it is essential according to the present invention that the molecular ratio of organic radical to metal oxide be within the limits specified, namely between 1:2 and 1:6.

The solutions of the complexes according to the present invention may be prepared by taking a soluble salt of zirconium, titanium or cerium such as zirconyl sulfate or titanyl sulfate and dissolving as much as possible thereof in water. Any concentration of the soluble salt may be utilized, but for reasons of economy it'is most suitable to utilize saturated solutions.

To the thus-formed solution is added citric acid or an alkali metal citrate such as sodium citrate or ammonium citrate (or tartaric. acid, malic acidior Iacticacidtorsalts thereof as the case may be) in an amount such that the ratio of citrate to the zirconium, titanium or cerium is betwen 1:2 and 1:6. In the case of zirconium, as previously indicated the ratio of citrate to zirconium is preferably between 1:25 and 1:4 and in the case'of titanium the ratio of citrate to titanium is preferably between 1:4.5

. thereof.

As previously indicated the solutions are introduced into the heaters or vats before or after the introduction of the paper pulp, before, after or along with the introduction of filler materials, before or after the introduction of resinates, but in all cases before the introduction of the precipitating salt such as aluminum sulfate which acts as fiocculant for the solution which should first penetrate intimately into the fibers of the paper pulp before the flocculation is caused.

It has been found that the precipitation in the interior of the fiber in accordance with the present invention of a hydrated oxide such as ZrO TiO or Ce0 has the effect of obtaining an opacity equivalent to that which could be obtained if instead one utilized 10 to 40 times more of the same powder such as TiO- Zr0 or CeO- the use of the powder alone resulting only in a clogging of the pores of the fiber.

Thus, in accordance with the invention, if utilizing a mineral filler such as TiO or ZnS it would be necessary to utilize 220% of the mineral filler in relation to the and in Test B.

dry pulp, in accordance with the present invention whereby the substance is made to precipitate in the fiber itself by the use of the solutions of the complexes of the present invention, it is sufi'icient to utilize between 0.051% by weight of the weight of the dry pulp to obtain the equivalent result. It may therefore be seen that the economy in the use of the pigments which are relatively expensive in accordance with the present invention is highly desirable.

As also indicated previously, the use of the solutions of the complexes in accordancewith the present invention may be combined with the use of known filler materials in powder form in orderto increase the whiteness and opacity of paper.

The following examples will more clearly illustrate the present invention and .the advantages thereof as compared to the known processes, the scope of the invention not, however, being limited to the specific details of the examples.

EXAMPLE I Test A Into a heater containing 250 kg. .of dry pulp dispersed in such amount of water that the water contained 5% of pulp was added 6 kg. of powdered TiO and the T10 were thoroughly mixed. The paper which was withdrawn had a weight of 67 g. per square meter and had the following properties as measured with a refiectometer in accordance with the I.C.I. system establishedin 1931:

Whiteness 83.25 Purity 0.64

Opacity 81.9

Test B Into a beater containing 250 kg. of dry pulp dispersed in water in an amount such that the water contained 5% by weight of pulp was added 2 kg. of powdered TiO and 4 liters of the solution of the complex of sodiumzirconium-citrate prepared as above described and containing a total of 130 g. of ZrO The pulp was-thoroughly mixed with the solution and the powdered TiO in the beater, aluminum sulfate was then added to the solution to cause flocculation of the ZrO, complex and the formed paper withdrawn had a weight of 67 g. per square meter. mined as in Test A and the values were as follows:

Whiteness Purity Opacity -It=may, therefore, be seenthat the'precipitation of 130 g. of 210 in the fibers giveidentical and even superior results to 4 kg. of powdered 'TiO the difference between the amount of powdered TiO used in Test A EXAMPLE II Sodium citrate was added to a solution of titanium sulfate dissolved in 18 liters of water, the amounts being adjusted in such manner that the solution contained 1 kg. of Ti0 and so that the molecular ratio of citrate to TiO was about 1:6. Sodium carbonate was then added to the solution until the pH thereof was raised to about 6.5. Upon addition of the sodium carbonate a precipitate formed which, after a short time, redissolved by itself.

The properties of this paper was deter- The pulp The efl ectiveness of this solution was tested as f ollowsf Test A Into a beating trough containing 250 kg. of dry pulp dispersed in a sufficient amount of water to have 5% pulp in the water was added 18 kg. of powdered TiOg. The final paper product had a Weight of 44 g. per square meter and had the following characteristics:

sufiicient amount of water to have 5% of pulp dispersed in the water was added 18 liters of the solution of the titanium complex, prepared as above, the 18 liters containing 1 kg. of TiO The T iO was precipitated from the solution by the addition of aluminum sulfate to the solution. The resulting paper had a weight of 44 g. per square meter and had the following chardispersed in a acteristics:

Whiteness 87.5 Purity 0.21 Opacity 84.6

From these tests .it may be observed that the same results are obtained'when of the present-invention with only $4 of the amount of TiO; than when using the According to the present invention, new industrial products are produced inasmuch as the metallic oxides TiQ2t.. r.O= .a.nd CeQ are-present in'or: omthe fib'e'r's of' spaces between the fibers.

the paper and not onlyin the According to another embodiment of the present invention, the solutions of thecomplexes invention may 'be utilized in combination with ,an albuminoid glue such as gelatin, eggwhite, lactalbumin, gluten or casein for the treatment and protection of various products of fiber, stone or wood and, more particularly, fibrous products having a cellulose base such as papers, paper pulps, wood fibers, wood pulps, straw, textile fibers and the like. The treatment of such ma terials with the complex solutions described above in combination with an albuminoid glue dissolved in the solution has the advantage not only of increasing-the.

whiteness and opacity of the resulting product, but'also in increasing the mechanical resistance thereof.

According to this embodiment of the presentinven tion, an albuminoid gluejis dissolvedin the solution-of invention. However, j the g; the, albuminoid glue. 7 than'lxetween 5 and 7,- and most preferably the pH should bebetween 5.75

according to embodiment;when

the complex of the present pH of these solutions con should rather be between.5.5 and and 6.5.

More particularly, utilizing a complex of sodium-ZrO citrate the molecular ratio of citrate'to ZrO should be preferably between 1:2 .9 i

and 1:3.4.

The quantity of the albuminoid glue such as gelatin in the solution should always be less than the amount which would result in flocculation or, in other words,=- in the solution. glue containing which would cause nephelometric trouble In the preparation of'the albuminoid solutions according to this embodiment of the invention, the pH of the sodium-Zro -citrate solution is always adjusted to between 5.5 and 7 by the addition of an alkali salt such as sodium carbonate before the incorporation of the albuminoid glue into the solution to prevent flocculation in the solution.

The solution may be applied to the substance to be treated, e.g., paper pulp, by immersing the paper pulp in the solution, by adding the solution to the beater or trough containing the paper pulp, by spraying the solution onto the paper pulp or by any other suitable method.

in order utilizing the complex solution Ti0 inthe powdered form.

of the present In the case of the paper being immersed in the solution,

it is merely necessary to removethe paper from the solution, allow it to drip, to cause retention of the complex and the albuminoid glue by the paper.

It is known that various micro-organisms annually destroy thousands of tons of cellulose fibers, of paper and paper'pulp mainly, which renders the storage of these products for a prolonged period of time either hazardous or impractical.

In the case of paper in particular, posed-in order to provide against this destructionto add various antiseptic products such as borax, salts of copper, mercury, lead, betanaphthol, etc. in the course of the preparation of the paper or the pulp, the amount i of the antiseptic being more or less, depending upon the particular antiseptic chosen and the genus of mold in the particular region in which the paper is to be used. These additions generally have no effect Lon Ithequality of the paper and on its mechanical characteristics. t

On the other hand, it is known that gelatin, the white of eggs, or other similar albuminoids employed in the paper industry as sizing agent for certain quality papers, present the inconvenience of constituting an excellent culture medium for microbes and other germs and therefore resulting in products which are particularly fragile. The products according to the present invention, on the other hand, thus have the following advantages:

(1) The rendering of the paper or the fiber imputresci-- ble because the products according to the present invention are microbe or mushroom resistant. q 7

(2) Acting as sizing agent for the paper by reason of the presence of the gelatin or other analagous glue (eggwhite, fish. glue, casein or other albuminoids).

(3) Increasing the mechanical resistance of the product. I

(4) Increasing the whiteness of the product (as against results obtained with chromate products which have the inconvenience of yellowing the resulting product).

It is very important to note that the proportion of citrate with respect to the proportion of ZrO' (or of the other organic acid radicals to the other metallic oxides such as Ti or CeO is critical. 1

It is known that the salts of zirconium have the ability of irreversibly flocculating gelatin. It is equally known that the alkalinization of a zirconium salt suchas the acid zirconylsulfate by sodium carbonate, for example,

leads to a flocculation of ZrO at a pH of 2.2-2.7 i'n proportion to the concentration of the zirconium salt.

It i's-known, on the other hand, that the precipitates of ZrO or even the solutions" of the acid zi'rconyl sulfate are soluble in an excess of citric acid or of the citrate of an alkali metal or ammonia containing about 3 molecules of citrate for 1 molecule of ZrO (which is actually the inverse of the molecular proportion of the present invention). However, neither the ZrO' precipitate nor the complex containing about 3 molecules of citrate per each molecule of ZrO is capable of flocculating gelatin- With the formation of a gel (the phenomenon which will herein be designated as the tanning of gelatin).

On the other hand, if the pH of the solution is less than 5.5, the solution soon flocculates and is unusable, while if the pH is greater than 7, the solution is incapable of tanning the gelatin.

Also, itis particularly surprising that in observing the conditions of the present invention, and particularly the conditions of molecular ratioof organic acid radical' such as citrate to metal oxide radical such as ZrO and and finally dry the paper-in order.

it has been pro-- poration of is desired, the gelatin, is used in the the pH, it is possible to obtain stable solutions, that is to say, in which there is neither flocculation of the ZrO nor flocculation of gelatin, this double flocculation, however, being produced automatically and irreversibly (with the, formation of a gel-not of a. salt-which apparently is constituted by a mixture of complexes of zirconium; of tannedgelatin and of various alkali salts) when't'he concentration of the solution is increased above a certain value as will be explained infurther detail.

indicated, pise'fit' iiivention, also comprises methodsof producing the-"solutions of the present inventiemtjhemetrtodeonsisting rm (m-Fornranen of aqueous solution of a soluble salt of zirconium and of citric acidbr' of an alkali metal or sari er ei "'dacid and adjusting the pH of the s lmionw-netweenss-and 7- by the addition of alkali hydroxide; carbonate-or bicarbonate; and

'-(B)1 The incorporation of gelatin or anotheralbii minoid glue into this solution in an amount below the amount at which flocculation of the gelatin in the solution occurs.

complex formed isnot immediately soluble in the cold.

It requires a certain time, which is about five minutes,

in the case where the molecular ratio of ZrO to citrate is 3.4, to 48 hours in the case where the molecular ratio of ZrO to citrate is 2.9, in order that the resulting solution should be perfectly clear from the point of view of nephelomctry.

The carbonate is added either after the citrate or at the same time, in a proportion such that the pH of the final solution is between 5.5 and 7, and preferably between 5175 and fijf Theproportion of the zirconium" saltin the solution is only limited bythe solubility of b the salt.

It is possible, according to the present invention, to

replace the sodium carbonate by the bicarbonate of sodium or to replace the sodium by another alkali metal, or another salt of an alkali metal or ammonium having a pH greater than 7, the salt being used in a quantity sufiicient to neutralize the acidity of the zirconium salt and to adjust the pH of the solution to Within thevalues specified.-

According to the present invention, once the citratezirconium complex forms a perfectly clear solution, the process passes intoa second stagethat is, the incorthe gelatin. Particularly where a whiteness form of a clear aqueous solution thereof having a pH of about 6. If the. pH of the gelatin is not between 5.5 and 7, the pH is adjusted by measured addition of a weak acid or a weak base.

It is not possible to add any quantities of gelatin to the solution of the. complex, on the contrary, the concentrations are strictly limited. As indicated, the quantity of gelatin tobe added is limited. Simple protesting may determine the quantity of gelatin to be added which will cause nephelometric disturbances in the solution, and after such tests it may then be determined the amount of gelatin below the amount which will cause the trouble, which amount is to be added to the solution.

The quantity of gelatin that may be incorporated into the defined complex solution varies on the one hand with the concentration of the zirconium salt of the solution, on the other hand with the quantity of citrate incorporated into the solution and, finally, with the dilucitrate-zirconium salt.

1n ;efie ct, it to obtain a stable solulhus, for 100 cc. of a solution containing initially:

Solution ZrO; (in g.) (in g.)

too to It is Possible to Dilution with Add Gelatin in the Solution Water before the Form of a 5% by Addition of Weight Solution Gelatin, Percent in the following Amounts, ml.

It may seen, from these figures, for example that the solutions 11, 25 and 34 are perfectly identical from the point of view of composition in zirconium salt and citrate-that is to say, each containing 1.1% Zr0 and 0.99% citrate. Nevertheless, in 100 cc. of solution 11 it is possible to add more than 367 cc. of the 5% gelatin solution without obtaining any nephelometric trouble. In solution 25, on the other hand, the nephelometric trouble is obtained with 26.4 cc. of the 5% gelatin solugelatin solution. It is therefore possible, according to the present invention, to prepare solutions containing variable quantities of gelatin for the same concentrations of zirconium, and while always obtaining satisfactory results.

It may be seen as well, from the above figures, that for a concentration of the zirconium-citrate salt which is regularly increased by evaporation of the solvent water, for example the solutions 5, 4, 3, Q, and l, the minimum quantity of gelatin which can be tanned by 100 cc. of the zirconium solution diminishes with the increase of the concentration of Zr0 from 147 to 0.1 cc., contrary to what one would predict.

Finally, the above figures show that for slight variations in the quantity of citrate added for the same quantity of ZrO as for example in solutions 2, 8, 13, and 17 where the quantities of citrate vary from 1.925 and 2.1% (therefore a variation of about 8%), there is a variation in the quantity of gelatin that can be added without nephelometric trouble from 1.1 to 147 cc.

It is therefore possible to predict the addition of greatly variable quantities of gelatin without flocculation while the complex is diluted and with a certainty of irreversible flocculation of zirconium and tanned gelatin when a portion of the solvent water is evaporated.

It is evident that in order to preserve the solutions perfectly stable, it is necessary to add less of the gelatin than is required in order to obtain nephelometric trouble, and in general 25% of this quantity is most usable, although the proportion may be varied between 2 and"% with good results. If, for example, solution 5 is preparedrlhatis to. say, a solution containing 1.1% 210 and 0.96% of citrate, and if only 20 cc. of 5% gelatin solution is added (1 g. of gelatin) in place of 147 cc., the solution will remain stable.

But after having impregnated the fibers of the paper or the like and starting the drying, When of the water are evaporated, the same results will occur as in the case of solution 2, that is to say, containing 3.3% ZrO and 1.99% citrate with three times the gelatin-e.g., 3 g. of gelatin. The complex gelatin-zirconium will flocculate as soon, because with solution 2.1.1 cc. of' 5% it EXAMPLE III To 1 liter of a solution of 5% of the acid sulfate of zirconium containing 22% of Zr0 at a pH of 1.7 is added 52.5 cc. of asolution containing 20% of trisodium citrate, 10% Na OO and 5% NaHCO The resulting pH of the solution is 6.2. When this solution is titrated with a solution of 5% gelatin, it is necessary to utilize 52.8 'cc. of the gelatin solution in order to obtain the nephelometric trouble. /3 of this quantity, that is 17.6 cc., permits the obtention of a stable solution conforming to the invention. The final mixture contains, therefor, for 1 liter of solution, 10.3 g. of ZrO 9.8 g. of citrate and 0.82 g. of gelatin, which is about 1% Zr0 1% citrate and 0.08% gelatin.

A piece of paper having a humidity content of 50% and a whiteness by opacity of 56% was treated with this solution by soaking and drying. The resulting paper was out in many ways. The example above given mentions the case of soaking. In the case of paper pulp and fibers in suspension in water, it is sufiicient to add to the pulp or to the suspension a quantity of solution which would be calculated by relation to the paper or the fiber or other material in suspension, the active elements of the solution having the tendency to fix themselves to the paper, fiber or other material.

' This quantity could be determined in each case as a function of the objects to be obtained and the material to be treated. 1

According to still another embodiment of the present invention, the usual filler materials such as powdered TiO or powdered ZnS may be dispersed either in those solutions not containing the gelatin or in the gelatinoontaining solutions. i

It has been found, according to the present invention, that particularly in the case of the gelatin-containing solutions, the powdered filler material remains in stable suspension in the solution which permits the use of lower quantities of the powdered filler and much more easily controllable conditions while obtaining the same results as in the known processes.

According to this embodiment, the process for the treatment of the paper or pulp may proceed either by: (a) first preparing a suspension of the powdered filler in the gelatin-zirconium complex solution and introducing this suspension into the beater, or (b-) introducing the solution of the gelatin-zirconium complex into the beater and then adding the filler, the suspension-according to the present invention-thus being prepared in situ.

Therefore, according to this embodiment of the present invention, new industrial products are actually produced, that is, fibrous materials such as paper containing ZrO (or CeO or TiO the white filler material such as the powdered TiO or ZnS, and the albuminoid glue as sizing.

A series of experiments is herein reported to illustrate the properties or the 'gelatin z'irconiumcomplex solution on the suspensions of the white filler materials.

These experiments were carried-out taking powdered TiOg as the filler material. In 7 identical cylinders there were prepared 7 solutions containing titamum oxide and the stability of these solutions was measured by observing their sedimentation.

Cylinder I.This cylinder contained a suspension of 10% Ti by weight in water. After about one minute all of the TiO fell to the bottom of the cylinder and the supernatant water was clear.

Cylinder H.This cylinder contained a suspension of 1% by weight of TiO in water. After about minutes the same phenomenon was observed as in cylinder 1.

Cylinder III.This cylinder contained a suspension of 0.1% by weight of TiO;,. The same phenomenon was observed as in the first two cylinders, but requiring 15 minutes.

Cylinder I V.-This cylinder contained a suspension of by weight of TiO in a solution containing 200 cc. per liter of the gelatin-zirconium solution previously described and containing 0.37% ZrO and 0.05% gelatin. After about 48 hours, only about half of the TiO,, fell to the bottom of the cylinder, the rest still remaining in suspension. The suspension is therefore very stable.

Cylinder V.This cylinder contained a suspension of 1% by weight of TiO in a solution containing 20 cc. per liter of the same gelatin-zirconium complex solution as in cylinder IV, that is, 0.0379% ZrO and 0.005% gelatin. After about 24 hours slightly less than half of the TiO fell to the bottom of the cylinder and the rest remained permanently in suspension.

Cylinder VI.This cylinder contained a suspension of 0.1% of TiO in a solution containing 2 cc. per liter of the same solution of gelatin-zirconium complex as in cylinders IV and V, that is, containing 0.0037% ZrO 12 and 0.0005% of gelatin. The same results were obtained as in cylinder V.

Cylinder VII.The preceding shows that very small quantities of gelatin-Zirconium complex, that is to say, in the order of several milligrams per liter, added to the suspension of TiO enormously increases the relative stability of the suspension.

In order to make certain that this increase of stability is not provided only by the fact of the presence of the gelatin in the solution, the gelatin constituting by itself a dispersing agent for TiO a seventh cylinder was prepared containing a suspension of 1% of Tit); in a solution of 0.005% of gelatin (the same solution as in cylinder V but without any ZrO After about three hours half of the TiO fell to the bottom and in 12 hours all of the TiO; fell to the bottom, the supernatant water had become perfectly clear.

This shows that the property of stabilizing the suspensions of the white fillers is peculiar to the solution of the gelatin-zirconium complex.

The combination, therefore, of the gelatin-zirconium complex solution with dispersed powdered filler material therefore permits in the paper industries ofavoiding practically completely any loss in the use of the filler (losses which in the case of TiO- for example, runs to about 50% of the TiO- introduced into the heaters). therefore, results in greatly lowering the price of the final product while obtaining equal whitenms and opacity with a. resistance increased as well as in providing a microbial and fungicidal action as previously described.

This advantage is again illustrated by the following table giving the values obtained on sheets of paper prepared in heaters in the laboratory:

These figures show that in reducing by half the quantity of T iO employed, there is obtained by the combina-' tion of the TiO; with the zirconium-gelatin complex of the present invention unchanged qualities of whiteness and opacity while still increasing the tearing strength of the paper.

Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can by applying current knowledge readily adapt it for various applications without omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of the generic or specific aspects of this invention and, therefore, such adaptations should and are intended to be comprehended within the meaning and range of equivalence of the following claims.

What is claimed as new and desired to be secured by Letters Patent is:

1. A method of improving the characteristics of a fibrous natural cellulose product, comprising the steps of applying to a fibrous natural cellulose stock an aqueous solution having a pH between 5-7 of at least one watersoluble complex of monovalent radical-metal oxideorganic acid radical salts, said monovalent radical being selected from the group consisting of alkali metals and ammonium, said metal oxide being selected from the group consisting of ZrO TiO and CeO and said organic acid radical being selected from the group consisting of citric acid, malic acid, tartaric acid and lactic aid, the molecular ratio of said organic acid radical to said metal oxide being between 1:2 and 1:6; and precipitating a substance including said metal oxide from said applied solution while said fibrous cellulose stock is in contact therewith, whereby said precipitated substance This,

Lassa is retained by said fibrous cellulose stock, increasing the whiteness and opacity thereof.

2. A method of improving the characteristics of a fibrous natural cellulose product, comprising the steps of applying to a fibrous natural cellulose stock an aqueous solution having a pH between 5-7 of at least one watersoluble complex of sodium-ZrO -citrate salts, the molecular ratio of citrate to 210 being between 112.5 and 1:4, and precipitating a substance including said ZrO from said applied solution while said fibrous cellulose stock is in contact therewith, whereby said precipitated substance is retained by said fibrous cellulose stock, increasing the whiteness and opacity thereof.

3. A method of improving the characteristics of a fibrous natural cellulose product, comprising the steps of applying to a fibrous natural cellulose stock an aqueous solution having a pH between 57 of at least one watersoluble complex of sodium-TiO citrate salts, the molecular ratio of citrate to TiO being between 1:45 and 1:6; and precipitating a substance including said Ti from said applied solution while said fibrous cellulose stock is in contact therewith, whereby said precipitated substance is retained by said fibrous cellulose stock, increasing the whiteness and opacity thereof.

4. A method of improving the characteristics of a fibrous natural cellulose product, comprising the steps of applying to a fibrous natural cellulose stock an aqueous solution having-a pH between 7 of at least one watersoluble complex of sodium-ZrO -citrate salts, the molecular ratio of citrate to ZrO being between 1:25 and 1:4, said solution containing between 26% by weight of ZrO and precipitating a substance including said ZrO from said applied solution while said fibrous cellulose stock is in contact therewith, Wherebysaid precipitated substance is retained by said fibrous cellulose stock, increasing the whiteness and opacity thereof.

5. A method of improving the characteristics of a fibrous natural cellulose product, comprising the steps of applying to a fibrous natural cellulose stock an aqueous solution having a pH between 5-7 of at least one watersoluble complex of sodium-TiO -citrate salts, the molecular ratio of citrate to TiO being between 1:45 and 1:6, said solution containing between 26% by weight of 'IiO ,and precipitating a substance including said TiO from said applied solution while said fibrous cellulose stock is in contact therewith, whereby said precipitated substance is retained by said fibrous cellulose stock, increasing the whiteness and opacity thereof.

6. A method of improving the characteristics of a fibrous natural cellulose product, comprising the steps of applying to a fibrous natural cellulose stock an aqueous solution having a pH between 5-7 of at least one watersoluble complex of monovalent radical-metal oxideorganic acid radical salts, said monovalent radical being selected from the group consisting of alkali nietals and ammonium, said metal oxide being selected from the group consisting of ZrO Ti0 and CeO and said or-, ganic acid radical being selected from the group consisting of citric acid, malic acid, tartaric acid and lactic acid, the molecular ratio of said organic acid radical to said metal oxide being between 1:2 and 1:6, said solution having distributed therethrough at least one insoluble powdered filler; and precipitating a substance including said metal oxide from said applied solution while said fibrous cellulose stock is in contact therewith, whereby said precipitated substance and said powdered filler are retained by said fibrous cellulose stock, increasing the whiteness and opacity thereof.

7. A method of improving the characteristics of a fibrous natural cellulose product, comprising the steps of applying to a fibrous natural cellulose stock an aqueous solution having a pH between 57 of at least one watersoluble complex of sodium-ZrO -citrate salts, the molecular ratio of citrate to ZrO being between 1:25 and 1:4, said solution having distributed therethrough powdered 14 TiO and precipitating a substance including said ZrC from said applied solution while said fibrous cellulose stock is in contact therewith, whereby said precipitated substance and said powdered TiO are retained by said fibrous cellulose stock, increasing the whiteness and opacity thereof.

8. A method of improving the characteristics of a fibrous natural cellulose product, comprising the steps of applying to a fibrous natural cellulose stock an aqueous solution having a pH between 57 of at least one watersoluble complex of monovalent radical-metal oxideorganic acid radical salts, said monovalent radical being selected from the group consisting of alkali metals and ammonium, said metal oxide being selected from the group consisting of ZrO TiO and CeO and said organic acid radical being selected from the group consisting of citric acid, malic acid, tartaric acid and lactic acid, the molecular ratio of said organic acid radical to said metal oxide being between 1:2 and 1:6; and treating said applied solution while said fibrous cellulose stock is in contact therewith with a soluble salt of a polyvalent' metal and a mineral acid in a quantity sufiicient to lower the pH of said solution to precipitate a substance includ-' ing said metal oxide therefrom, whereby said precipitated substance is retained by said fibrous cellulose stock, increasing the whiteness and opacity thereof.

9. A method of improving the characteristics of a fibrous natural cellulose product, comprising the steps of applying to a fibrous natural cellulose stock an aqueous solution having a pH between 5-7 of at least one watersoluble complex of monovalent radical-metal oxideorganic acid radical salts, said monovalent radical being selected from the group consisting of alkali metals and ammonium, said metal oxide being selected from' the group consisting of ZrO TiO and CeO and said organic acid radical being selected from the group consisting of citric acid, malic acid, tartaric acid and lactic acid, the molecular ratio of said organic acid radical to said metal oxide being between 1:2 and 1:6; and treating said applied solution while said fibrous cellulose stock is in contact therewith with aluminum sulfate in a quantity sufiicient to lower the pH of said solution to precipitate a substance including said metal oxide therefrom, whereby said precipitated substance is retained by said fibrous cellulose stock, increasing the whiteness and opacity thereof.

10. A method of improving the characteristics of a fibrous natural cellulose product, comprising the steps of applying to a fibrous natural cellulose stock an aqueous solution having a pH between 5-7 of at least one watersoluble complex of monovalent radical-metal oxide-or ganic acid radical salts, said monovalent being selected from the group consisting of alkali metals and ammonium, said metal oxide being selected from the group consistingof 'ZrO TiO and CeO and said organic acid radical being selected from thegroup consisting of citric acid, malic acid, tartaric acid and lactic acid, the molecular ratio of said organic acid radical to said metal oxide being between 1:2 and 1:6; and treating-said applied solution while said fibrous cellulose stock is in contact therewith with thorium sulfate in a quantity sufiicient to lower the pH of said solution to precipitate a substance including said metal oxide therefrom, whereby said precipitated substance is retained by said fibrous cellulose stock, increasing the whiteness and opacity thereof.

11. A method of improving the characteristics of a fibrous natural cellulose product, comprising the steps of applying to a fibrous natural cellulose stock an aqueous solution having a pH between 5.5-7 of at least one watersoluble complex of monovalent radical-metal oxide-organic acid radical salts, said monovalent radical being selected from the group consisting of alkali metals and ammonium, said metal oxide being selected from the group consisting of ZrO ,-TiO and CeO and said organic acid radical being selected from the group consisting of citric acid, malic acid, tartaric acid and lactic acid, the molecular ratio of said organic acid radical to said metal oxide being between 1:2 and 1:6, said solution having dissolved therein an albuminoid glue in a predetermined amount below the amount at which flocculation of said albuminoid glue in said solution occurs; and precipitating said albuminoid glue and said complex including said metal oxide from said applied solution while said fibrous cellulose stock is in contact therewith, whereby the precipitate is retained by said fibrous cellulose stock, increasing the whiteness and opacity thereof. Y

12. A method of improving the characteristics of a fibrous natural cellulose product, comprising the steps of applying to a-fibrous natural cellulose stock an aqueous solution having a pH between 5.5-7 of at least one watersoluble complex of monovalent radical-metal oxide-organic acid radical salts, said monovalent radical being selected from the group consisting of alkali metals and ammonium, said metal oxide being selected from the group consisting of ZrO,, TiO; and :20;, and said organic acid radical being selected from the group consisting of citric acid, malic acid, tartaric acid and lactic acid, the molecular ratio of said organic acid radical to said metal oxide being between 1:2 and 1:6, said solution having dissolved therein gelatin in a predetermined amount below the amount at which flocculation of said gelatin in said solution occursyand precipitating said gelatin and said complex including said metal oxide from said applied solution while said fibrous cellulose stock is in contact therewith, whereby the precipitate is retained by said fibrous cellulose stock, increasing the whiteness and opacity thereof.

13. A method of improving the characteristics of a fibrous natural cellulose product, comprising the steps of applying to a fibrous natural cellulose stock an aqueous solution having a pH between 5.5 and 7 of water-soluble complex of sOdium-ZrO -citrate salts, the molecular ratio of citrate to Zr0 being between 1:2.9 and 1:3.4, said solution having dissolved therein gelatin.in a predetermined amount below the amount at which flocculation of said gelatin in said solution occurs; and precipitating said gelatin and said complex including said ZrO from said applied solution while said fibrous cellulose stock is in contact therewith, whereby the precipitate is retained by said fibrous cellulose stock, increasing the whiteness and opacity thereof.

14. A method of improving the characteristics of a fibrous natural cellulose product, comprising the steps of applying to a fibrous natural cellulose stock an aqueous solution having a pH between 5.75 and 6.5 of water-soluble complex of sodium-ZrO -citrate salts, the molecular ratio of citrate to ZrO being between 1:29 and 1:3.4, said solution having dissolved therein gelatin in a predetermined amount below the amount at which flocculation of said gelatin in said solution occurs; and precipitating said gelatin and said complex including said 210 from said applied solution while said fibrous cellulose stock is in contact therewith, whereby the precipitate is retained by said fibrous cellulose stock, increasing the whiteness and opacity thereof.

15. A method of improving the characteristics of a fibrous natural cellulose product, comprising the steps of spraying onto a fibrous natural cellulose stock an aqueous solution having a pH between 5.5 and 7 a water-soluble complex of sodium-ZrO -citrate salts, the molecular ratio of citrate to ZrO being between 122.9 and 1:3.4, said solution having dissolved therein gelatin in a predetermined amount below the amount at which flocculation of said gelatin in said solution occurs; and evaporating water from said applied solution while said fibrous cellulose stock is in contact therewith so as to precipitate said gelatin and said complex including said ZrO from said applied solution while said fibrous cellulose stock is in contact therewith, whereby the precipitate is re- 16 tained by said fibrous celluose stock, increasing the whiteness and opacity thereof.

16. A method of improving the characteristics of a fibrous natural cellulose product, comprising the steps of immersing a fibrous natural cellulose stock in an aqueous solution having a pH between 5.5 and 7 of water-soluble complex of SOdiUlIl-ZIOg-Clililifi salts, the molecular ratio of citrate to ZrO being between 1:29 and 1:3.4, said solution having dissolved therein gelatin in a predetermined amount below the amount at which flocculation of said gelatin in said solution occurs; and removing the thus immersed fibrous cellulose stock from said solution and allowing the water of said applied solution to evaporate so as to precipitate said gelatin and said complex including said ZrO from said applied solution while said fibrous cellulose stock is in contact therewith, whereby molecular ratio of citrate to Zr0 being between 112.9

and 1:3.4, said solution having dissolved therein gelatin in a' predetermined amount below the amount at which flocculation of said gelatin in said solution occurs; and removing the thus immersed fibrous cellulose stock from said solution and allowing the water of said applied'solution to evaporate so as to precipitate said gelat'm and said complex including said ZrO from said applied solution while said fibrous cellulose stock is in contact therewith, whereby the precipitate is retained by said fibrous cellulose stock, increasing the whiteness and opacity thereof.

18. A method of improving the characteristics of a fibrous natural cellulose product, comprising the steps of applying to a fibrous natural cellulose stock an aqueous solution having a pH between 5.5-7 of at least one water-soluble complex of monovalent radical-metal oxideorganic acid radical salts, said monovalent radical being selected from the group consisting of alkali metals and ammonium, said metal oxide being selected from the group consisting of ZrO TiO and CeO and said organic acid radical being selected from the group consisting of citric acid, malic acid, tartaric acid and lactic acid, the molecular ratio of said organic acid radical to said metal oxide being between 1:2 and 1:6, said solution having dissolved therein an albuminoid glue in a predetermined amount below the amount at which flocculation of said albuminoid glue in said solution occurs, and said solution having distributed therethrough at least one insoluble powdered filler; and precipitating said albuminoid glue and said complex including said metal oxide from said applied solution while said fibrous cellulose stock is in contact therewith, whereby the precipitate and said powdered filler are retained by said fibrous cellulose stock, increasing the whiteness and opacity thereof.

19. A method of improving the characteristics of a fibrous natural cellulose product, comprising the steps of applying to a fibrous natural cellulose stock an aqueous solution having a pH between 5.5-7 of a water-soluble complex of SOdium-ZrO -citrate salts, the molecular ratio of citrate to ZrO being between 1:2 and 1:6, said solution having dissolved therein gelatin in a predetermined amount below the amount at which flocculation of said gelatin in said solution occurs, and said solution having distributed therethrough at least one insoluble powdered filler; and precipitating said gelatin and said complex including said ZrO from said applied solution while said fibrous cellulose stock is in contact therewith, whereby the precipitate and said powdered filler are retained by said fibrous cellulose stock, increasing the whiteness and opacity thereof.

20. A method of improving the characteristics of a fibrous natural cellulose product, comprising the steps of applying to a fibrous natural cellulose stock an aqueous solution having a pH between 5.5-7 of a water-soluble complex of sodium-TiO -citrate salts, the molecular ratio of citrate to Ti0 being between 1:2 and 1:6, said solution having dissolved therein gelatin in a predetermined amount below the amount at which flocculation of said gelatin in said solution occurs, and said solution having distributed therethrough at least one insoluble powdered filler; and precipitating said gelatin and said complex including said TiO- from said applied solution while said fibrous cellulose stock is in contact therewith, whereby the precipitate and said powdered filler are retained by said fibrous cellulose stock, increasing the whiteness and opacity thereof.

References Cited in the file of this patent UNITED STATES PATENTS 1,692,372 Gardner Nov. 20, 1928

Claims

1. A METHOD OF IMPROVING THE CHARACTERISTICS OF A FIBROUS NATURAL CELLULOSE PRODUCT, COMPRISING THE STEPS OF APPLYING TO A FIBROUS NATURAL CELLULOSE STOCK AN AQUEOUS SOLUTION HAVING A PH-BETWEEN 5-7 OF AT LEAST ONE WATERSOLUBLE COMPLEX OF MONOVALENT RADICAL-METAL OXIDEORGANIC ACID RADICAL SALTS, SAID MONOVALENT RADICAL BEING SELECTED FROM THE GROUP CONSISTING OF ALKALI METALS AND AMMONIUM, SAID METAL OXIDE BEING SELECTED FROM THE GROUP CONSISTING OF ZRO2, TIO2 AND CEO2 AND SAID ORGANIC ACID RADICAL BEING SELECTED FROM THE GROUP CONSISTING OF CITRIC ACID, MALIC ACID, TARTARIC ACID AND LACTIC AID, THE MOLECULAR RATIO OF SAID ORGANIC ACID RADICAL TO SAID METAL OXIDE BEING BETWEEN 1:2 AND 1:6, AND PRECIPITATING A SUBSTANCE INCLUDING SAID METAL OXIDE FROM SAID APPLIED SOLUTION WHILE SAID FIBROUS CELLULOSE STOCK IS IN CONTACT THEREWITH, WHEREBY SAID PRECIPITATED SUBSTANCE IS RETAINED BY SAID FIBROUS CELLULOSE STOCK, INCREASING THE WHITENESS AND OPACITY THEREOF.