US2833620A - An inorganic flexible fibrous material consisting of the asbestos-like form of an alkali metal titanate and its preparation - Google Patents

Description

- 2,833,620 AN INORGANIC FLELE FIBROUS MATERIAL CONSISTZNG on THE ASBESTOS-LIKE FORM or AN ALKALI METAL 'TITANATE AND ITS PREP- AH N Thurman E. Gier and Paul L. Salz'berg, Wilmington, Del and Howard S. Young, Chadds Ford, Pa., assignors to.E. I. du Pont de Nemours and Company, Wilmington, Del.,' a corporation of Delaware "Nd Drawing. Application September 24, 1954 Serial No. 458,279

7 27 Claims. (Cl. 23-9-51 1 has been'described as producing other titanates, suchas K Ti O and K Ti O .v These prior art alkali metal titanates are soluble in water or either soluble or decom- 200atmos pheres. I After reaction, the mixture is then subjected to extraction, preferably with water or dilute mineral acid, until unreacted alkali, i. e., essentially no more alkali, is extracted therefrom.

The process whereby'the new alkali metal titanates are formed involves the reaction in the presence of water of! a titanium compound, preferably a titanium oxide or hydrated oxideQwith analkali metal oxide ora suitable basic alkali metal compound, such'as the carbonate or hydroxide, at a temperature of at. least 400 C. and

; pressure of at least 200 atmospheres. In this reaction,

posed byv aqueous acids orba'ses; However, there has been. no report in the literature of an asbestos-like or fibrous alkali metal titanatexwhich' is water-insoluble.

. It is an object of this invention to provide fibrous alkali metal titanates and amethod for their preparation. A further object is to provide fibrous alkali metal titanates which are water-insoluble. Another-"Object is to provide fibrous alkali metal'titanates in the form of asbestos-like fibers. Other objects will'appear hereinafter. L These and other objects of this invention are accomplished by providing new fibrous alkali metal titanates which are water-insoluble and whereinthe alkali metal has an atomic number of at least eleven; The alkali metal titanates of this invention have a fibrous structure in which one dimension of the crystal is longer than the other dimensions by a factor of atleast five and generally ten to one hundred and up to.1000 or more, i. e.,

the ratio of length to width of the crystal at least 5:1 and generally 10:1 to 100:1 and up to l000:1 or more. This fibrous product is purified and separated from any other alkali metal or titanium compounds by pressure-resistant vessels inert to the reagents present are used. The ratio of charge of alkali metal oxide, e. g., potassium oxide, to titanium oxide, can vary from 1:6

to 12:1, with the preferred ratio being from 3:1 to 8:1."

Thetitanium compound employed. is generally present in finely divided or uniformly dispersed form. The alkali metal compound is generally present in solution or suspended in Water. The, reaction is generally efiectcd at temperatures of 400 to S00 C. or even higher, with temperatures of 600 to 700 C. preferred. The reaction is generally finished in times of a few hours or less. The new fibrous alkali metal titanates of this invention are readily separatedfrom undesired products, such as unused starting materials, vby virtue of their insolu'bility and lack of reactivity to water, dilute and concentrated mineral acids, including hydrochloric and sulfuricacid, bases such as potassium hydroxide, and aqueous salt solutions. w I

In thefollowing examples, parts are by weight, and all of the reactions are conducted in sealed, collapsible; platinum vessels which are subjected to the prescribed physical conditions, in apparatus capable of operating under such conditions. These examplesarefor purposes of illustrationof preferred procedures for the preparation of the novel fibrous alkali vention. i o

I I Example I o p A mixture of 0.1329 part titanium dioxide (anatas'e),

0.0665 part sodium hydroxide (Na O/TiO =1/2) and 0.1665 part water was heated to 625 C. at a pressure of about 2800 atmospheres. These conditions were attained in about 25 minutes at which time the heating was discontinued and the mixture allowed to return to atmospheric conditions. The entire solid product comprised fibers about 25 microns long and having a length to diameter ratio of about 100/1. The fibrous product was insoluble in aqueous solutions.

. Example II A, mixture of 0.2304 part titanium dioxide (anatase) and 0.133 part IO N sodium hydroxide aqueous solution of long fiberswhose properties were the same as those scribed in the titanium prior art; Furthermore, the

alkali metal titanates of this invention do not hydrate,

2 i. e., .do not absorb water of crystallization and thus do" not contain water of crystallization. 7

It has now been found that fibrous as well as waterinsolub1e and non-hydrated alkali metal titanates can be prepared by reacting in the presence of water, a water-soluble basic oxygen-containing alkalimetal compound, such an an alkali metal hydroxide, wherein the alkali metal has an atomic number of at least eleven, with an oxygen-containing titanium compound, such as titanium dioxide, in a molar ratio of 1:6 to 12:1, calculated as alkali metal oxide to titanium dioxide, at'a temperature of at least 400 C. under pressureofsat least.

(Na O/TiO =l/6) was heated 1.5 hours at 625 C. and 3000 atm. pressure. Upon returning the product to atmospheric conditions it was found to contain fibrous sodium titanate, of which atleast 5% was in the form of the productof Example I.

v Exaniple III A mixture of 0.0250 part titanium dioxide (rutile) and 1.05 part 10 N potassium hydroxide aqueous solu tion (K O/TiO =12/ 1) was heated 1.5 hours at 625 C. and 3000 atm. pressure. Upon returning the mixture to atmospheric conditions, it was found that about of the potassium tita'nate product was in the form of long fibers which were insoluble in aqueous solutions.

. V I Example IV A mixture of 0.16; part titanyl sulfate and 0.35 10 N potassium hydroxide aqueous solution (K O/TiOSO 1/ 1) I Patented May 6, 1958 metal titanates of t i in- Example III.

was heated '1 hour art-625 C. and 3000 atm. pressure. Upon cooling to room temperature, the entire solid product comprised a fluffy, light gray water-insoluble asbestoslike material. Individual; fibers were about .15 microns Emma w f A mixture of 0.500 part titanium dioxidelanatase), 2.6parts potassium carbonate (K O/TiO,:3/-l) and 4 parts water was heated *2 hours -at- 625' C. and 3000 atmospheres pressure. After returning to atmospheric conditionsythe entire productcomprising fibrous potassium titanate suspeudedyin an aqueous",;alkaline. medium was titrated potentiometrically with a standard solution of hydrochloric acid; It was found that'0ll04 part of .the alkali (as K wasnot available -for-neufl'alization by'the acid and was therefore combined "with the 0.5 part titania. This corresponds to a ratio'of, K Q/TiQ,=1/'S.7 in the,

product. {1 The suspensionwasfiltered and thesolid product I washed and driedtoobtain 0.045 part long fibers ranging up to 1 cm. in length and about lmicron in diameter and 0.547' partof mattedshort'fibersless than] mm. in lengthyi. a; Pthese' flexible fibers'were feltedinto a mat.

"The totalweight of product *from part titauia. was

therefore 0. 592 part. Onthe-assrimptiqnthat all of the weight increase is K o ithe K O/TiO ratio is 1/6.4 in

l the product. Analysis :of the fibrous potassium titanate revealed 50.3% titanium and 12.6% ing a KgO/TiO, ratio of 1/ 6.8.

Similar preparations ofpotassium. titanate from potassium earbonateand ,anatase were conducted in which the ratio of the. reactants was varied. The results were. as follows: i

potassium indicatmo Tior Ratio in Product Based In Reactants l s NQn- Weight Kand Ti tltratable of Analyses Alkali Product 1 1 1 1/5.8 l/6.6 1/6.9 sir r rr 116.0 1/6.4 1/7.4

The products were. asbestos-like water-insoluble fibers.

Example VII A mixture of 0.1 pa t tita ium dioxide (mm); 0 32 p r u py h s a s. K33 1 (Ks 1/IiQr=.-

and 0.4 part water was heated 0.5 hour": a t ,625C. and

3000 atm. pressure. After the reaction mixture was returned to atmospheric conditionsyit was found to contain short potassium titanate water-insoluble fibers having an approximate length of microns and a diameter of 1 micron.

Example VIII" I \A of 0.1 parturanium-mums(muse 6.6. arbonate (RbzO/TiQlfl/l) an 0.9 part water, was heated 3, hours at 625 C. and 3000 atm. pressure. The produetcomprised in preponderant amount fiexible water insoluble fibers having diameters ranging to less than 1 micron and lengths ranging to over 1000 microns. l. 1

aaaaeao '4 7 Example IX A mixture of 0.1 part titanium dioxide (anatase), 1.222

part cesium carbonate (Cs 0/TiO =3/l) and 0.9 part water was heated 3 hours at 625 C. and 3000 atm. pressure. The product comprised, in major amounts, waterinsoluble fibers of-up to about 200 microns long and about 1 micronindiameter.

Example X A mixture of 0.1336 part titania (titanium dioxide) and 1.40 part 10 N aqueous potassium hydroxide solution (KgO /TiOy-s-fi/ 1) was heated 1.5 hours at 450 C. and 10.00 atmrpressure. The product comprised grayish white, long water-insoluble fibers of potassium titanate.

The new products of this invention are asbestos-like fibrous, non-hydrated,- alkali metal titanates which are water-insoluble and wherein the alkali metal has an atomic number of at least eleven. Chemical analysis of the fibrous alkali metal titanates of this invention indicates that :they correspond in chemical composition to the :gen-

' to 7. Determination ofthe non-,titratable alkali in the Pro ucts resulting from ;the process :of this inventionkindica sis :thatumhasa value :of about .6 in the fibrous alkali metal titanates corresponding. in chemical composition 'to thefulfmula .M,Q(TiQ,),.wherein M is an alkali metal of atomic number .of at least eleven. Thus, by determination of uonetitratable alkali, the fibrous alkali metal itanates are indicated .to have the general iformula s s eQisi. wherein 1M is an alkali metal having atomic number .;of .,at, leastaeleven such as potassium, sodium,

u idiumand cesium. 0futhe alkali metals, sodium and potassium are-cheaper. and more readily .available'thnn the other alkali. metals and z-thereforemost preferred.

These newiproducts .arencharacterized by their insolubilityaud lack of reactivitywith water and'aqueous solutions of mineraLacida-bases or. salts. They do not .form hydrates ji. .e,.. :absorb water of crystallization. The titanates of-alkali metals. of atomic number of 11 or greate ilv e,, sodium, potassium, rubidium and cesium, are .obtaineddn the .forrnrof' fibers, i. e., asbestos-like, and have a length to diameter ratio of at least 5:1 and usual ly of at least .1 0, 1. .A'SaShOWll in .the examples, .thelength is,generally .10 to .1000 times the diameter of the fiber. As shown by ExampleiVHI. there are obtained .by the process of this ,invention alkali metal titanates inthe form of water-insoluble flexible :fibers having a ratio of length toldiameterranging to over l000:1.

In the preparation of the new alkali metal titanates, an alkali .metalcornpound such asthe carbonate or by droxide is generally employedalthough other waterssoluble compqunds can be used, c. .g., :an alkali metal phos- Phate. The alkali metal icompofund is-preferably basic es .-a basic reaction with water. Particularly useful arethe alkllimetal hydroxides andcarbonates, i. .e., basic QEYEn-wntainiugalkali metal compounds which are soluble in water or which form the alkali metalzhydrosride in aqueous; solution.

Thetitanium source can be a titanium oxide, or salt. Particularlysuitable in viewof its availability isr'titanium dioxide. However, soluble titanium compounds-sucks:-

it nyls lfalc or lower titanates can be employed.

It is to be noted The new products of or bases. Advantage is taken of this property in the purification of the new titanates since alkali metal hydroxides, carbonates or other salts are water soluble. In view of the ease of removal of other alkali'metal compounds than those combined'with titanium in the manner required for the new products of this invention, the alkali metal starting compound can be, and usually is, employed in slight'excess over the theoretical value; When titanium dioxide is present in the final product, it is generally removed by taking advantage of its greater density and higher sedimentation rate.

The reaction between the titanium and alkali metal compounds is effected attemperatures of at least'400 C. and generally less than 800 C. with the temperature preferably at 600 to 700 C. The reaction requires the presence of water. To retain water in the reaction media under these conditions necessitates the use of pressures of at least 200 atmospheres, and generally 500 atmospheres or more, as well as equipment that will withstand the conditions and reagents employed. The upper pressure limit is dependent only on the equipment employed. Although pressures of 10,000 atmospheres can be used, such pressures require strong and expensive equipment. Pressures of the order of 1000 to 4000 atmospheres are relatively easy to maintain and these pressures are preferred. The reaction time is generally short, e. g., a few minutes to a few hours.

The new asbestos-like fibrous alkali 'metal titanates of this invention are inert to many corrosive chemical reagents. For example, these titanates are insoluble in boiling 50% caustic, insoluble in aqueous acids such as sulfuric acid and concentrated hydrochloric acid, and unattacked by chlorine.

The fibrous alkali metal titanates are particularlyuseful in applications where the inertness and physical properties of an absestos-type material are required, e. g., in reinforcing agents, in fibers or papers and as insulation material.

As many apparently widely different embodiments of this invention may be made without departing from the spirit and scope thereof, it is to be understood that this invention is not limited to the specific embodiments thereof except as defined in the appended claims.

We claim: 8 v

1. A method for preparing an absestos-like fibrous,

'water-insoluble alkali metal titanate which comprise reacting in the presence of water, a water-soluble basic oxygen-containing alkali metal compound, wherein the alkali metal has an atomic number of at least eleven, with an oxygen-containingtitanium compound in a molar ratio of 1:6 to 12:1, calculated as alkali metal oxide to titanium dioxide, at a temperature of at least 400 C. under a pressure of at least 200 atmospheres, and separating as the resulting product an alkali metal titanate in the form of water-insoluble, non-hydratable, flexible fibers.

2. A method for preparing'an asbestos-like fibrous, Water-insoluble alkali metal titanate which comprises reacting in the presence of water, an alkali metal hydroxide, wherein the alkali metal has an atomic number of at least eleven, with titanium dioxide in a molar ratio of 1:1 to 8:1, calculated as alkali metal oxide to titanium dioxide, at a temperature of 400 C. to 800 C. under a pressure of 500 to 4000 atmospheres, and separating as the resulting product an alkali metal titanate in the form of water-insoluble, non-hydratable, flexible fibers.

3. A method for preparing an absestos-like fibrous, water-insoluble alkali metal titanate as set forth in claim 1, wherein said alkali metal compound is an alkali metal hydroxide in which the alkali metal has an atomic number of at least 11.

4. A method for preparing an asbestos-like fibrous, water-insoluble alkali metal titanate as set forth in claim 1, wherein said alkali metal compound is an alkali metal thealkali metal has an atomic number of 1:6 to 12:1, calculated as alkali metal oxide to sodium'titanate in the form of water-insoluble, nontitanium dioxide, at a temperature of 400 to 800] C. under a pressure of 500 to 4000 atmospheres, and separating as the resulting product an alkali metal titanate in the form of water-insoluble, non-hydratable, flexible fibers.

7. A method for preparing an asbestos-like fibrous,

water-insoluble sodium titanate which comprises reacting in the presenceof'water, sodium hydroxide with titanium dioxide in a molar ratio of 1:6 to 12:1, calculated as sodium oxide to titanium dioxide, at a temperature .of

600 to- 700 C., undera pressure of l000'to 4000 atmospheresyand separating as the resulting product sodium titanate in the form of water-insoluble, nonhydratable, flexible fibers.

' 8. A method for preparing an asbestos-like fibrous, water-insoluble potassium titanate which comprises reacting in the presence of water, potassium hydroxide with 'titanium dioxide in a molar ratio of 1:6 to 1221,:

calculated as potassium oxide to titanium dioxide, ata temperature of 600 to 700 C., under a pressure .of 1000 to 4000 atmospheres, and separating as theresulting product potassium titanate in the form of waterinsoluble, non-hydratable, flexible fibers.

9. A method for preparing an asbestos-like fibrous, Water-insoluble alkali metal titanate which comprises reacting in the presence of water, an alkali metal carbonate wherein the alkali'metal has an atomic number of at least 11, with titanium dioxide in a molar ratio of 1:6

to 12:1, calculated as alkali metal oxide to titanium dioxide, at a temperature of 400 to 800 C. under a pressure ,of 500 to 4000 atmospheres, and separating as the resulting product an alkali metal titanate in the form of water-insoluble, non-hydratable, flexible fibers.

10. A method for preparing an asbestos-like fibrous,

water-insoluble sodium titanate which comprises reactmg in the presence of water, sodium carbonate with titanium dioxide in a molar ratio of 1:6 to 12:1, calculated as sodium oxide to titanium dioxide, at a temperature of 600 to 700 C., under a pressure of 1000 to 4000' hydratable, flexible fibers.

'ing in the presence of water, potassium carbonate with 1 11. A method for preparing an asbestos-like fibrous, water-insoluble potassium titanate which comprises reacttitanium dioxide in a molar ratio of 1:6 to 12:1, calculated as potassium oxide to titanium dioxide, at a tempera- I ture of 600 to 700 C., under a pressure of 1000 to 4000 atmospheres, and separating as the resulting product potassium titanate in the form of water-insoluble,

non-hydratable, flexible fibers.

12. As a new inorganic fibrous material, alkali metal titanate crystalline fibers each having a ratio of length to width of at least 10:1, and each being sufficiently flexible to be felted, said fibers being insoluble in water, not absorbing water of crystallization to form a hydrate, and having the general formula M O-(TiO wherein M is an alkali metal having an atomic number of at least 11 and n has a value of from 6 to 7.

13. As a new inorganic fibrous material, sodium titanate crystalline fibers each having a ratio of length to width of at least 10:1, and each being sufliciently flexible to be felted, said fibers being insoluble in water, not absorbing water of crystallization to form a hydrate,

to width of vat least 'lOzl jand each being sufficiently flexible to be "felted, said fibers being insoluble in water, not absorbing water of crystallization. to form a hydrate, and ha'vin'g the general formula M O-(TiO wherein M is rubidium andn has a value of fro m 6 to 7.

t a I new inorganic. fibrous: material, cesium titanate flcr y stalline fibers. each having a ratio. of length to width of at least 10:1, and :each being sufficiently ilef xible to. be felted, said fibers being insoluble in water,

a s i water f Cr st l ion to fame hyd e. ancihavi s the general fo m la zQ (non... whe ei M is ce'siurn and nfhas a value offfrom ,to 7.

17. An inorganic flexible, fiber: havingyta ratio of length to width of at least :1consisting of an alkali metal; titanate fiber which is sufficiently flenibleto' be f lted. and which is insoluble in water, doesnot absorb water of crystallization, to form ahydrate; and having the general: formula p-(11.09,, wherein M, is an alk alijme't'al having an atomic number of at least 11 and n hasa value of from.6 to 7.

18.f An inorganic flexible fiber having a ratio of length' to width of "at least 10:1 consistingof a titanate 'fiberflwhich is sufficiently flexible to be felted and which is insolublejin'water, does not absorb :water of crystallization totform ahydrate, i dhaving the gqneral, formula MQQEKTiQQm wherein M is sodium andnhas a value ofifrom 6 to 7.

g An inorganic flexible. fiber having a .ratio of length towidthof at least 10:1 consistingof a potassium titanate fiber. which is sufliciently flexible tobe felted and whichis insoluble in water, doesnot absorb water of crystallization to form a hydrate, and having the general formula M,o-(Tio,).,,, wherein M is potassium and n has a'value of fror'n'6 to 7. I g

20. An inorganic flexible fiber having a ratio of length to widthof at least 10:1 consisting of a rubidium titanate fiber which is sufliciently'flexible to be felted .and which is insoluble in water, doesnot absorb water of crystalliza- '22 A new inorganic fibrous material comprising.

alkalimetal titanate crystalline f bers each having a ratio .of length to width of at least 10; 1, and each being it sufliciently flexible to be felted,said fibers being insoluble in water, not absorbing water of crystallization to form a hydrate, ,and having the general formula M' Ti o wherein M is an alkali metal having an atomic number of at least 11.

'23. A new inorganic fibrous material comprising potassium titanate crystalline fibers each having a ratio of length to width of at least 10:1, and each being sufficiently flexible to be felted, said fibers beingqinsoluble inwater, not absorbing water of crystallization to form a hydrate, and having the general formula MgTioom, wherein M is potassium.

24. Inorganic flexible fibers,. each having a ratio of lengthto width of at least 10:1 and consistiugof an alkali metal titanate fiber which is sufficiently flexible to be felted and which ,is insoluble in water, does not absorb water-of crystallization to form a hydrate, and having the general formula Mfli o wherein M is an alkali metal having an. atomic number of at least 11.

2 5. Inorganic flexible fibers, each having a ratio of length to width of at vl east .1 0:l and consisting of an alkali metal titanate fiber which is sufficiently flexible to be felted and which is insoluble :in water, does not absorb water of crystallization to form a hydrate, and having the general formula M Ti O wherein M is potassium.

26. An insulating composition comprising amass of metal Jtitanate crystalline fibers which are sufliciently flexible to be felted andwhich are insoluble in water, do not absorb water of crystallization to form a hydrate, and have the general formula M 13 0 wherein M is an alkali metal having an atomic number of at least '11.

27. An insulating composition comprising amass of M potassium titanate crystalline fibers which are sufficiently flexible to be felted and which are insoluble in water, do not absorb water of crystallization to form a hydrate and have the general formula iM Ti O wherein M is potassium.

References Cited in the file of this. patent UNITED STATES PATENTS OTHER REFERENCES Barksdale: Titanium," 1949, pages 97-101, Ronald Press Co., N, Y. C.

Mellor: Comprehensive Treatise von Inorganic and Theoretical Chemistry, vol. 7, page 51, Longmanns, Green ,8; CQ,,N. Y. 0., 19 27.

Gmelin Kraut: Handbuch der Anorganischen Chemie Band 3, Abt. 1, page 84, Carl Winters Universtatsbuchhandlung, 1912,

Claims (2)

1. A METHOD FOR PREPARING AN ABSESTOS-LIKE FIBROUS WATER-INSOLUBLE ALKALI METAL TITANATE WHICH COMPRISE REACTING IN THE PRESENCE OF WATER, A WATER-SOLUBLE BASIC OXYGEN-CONTAINING ALKALI METAL COMPOUND, WHEREIN THE ALKALI METAL HAS AN ATOMIC NUMBER OF AT LEAST ELEVEN, WITH AN OXYGEN-CONTAINING TITANIUM COMPOUND IN A MOLAR RATIO OF 1:6 TO 12:1, CALCULATED AS ALKALI METAL OXIDE TO TITANIUM DIOXIDE, AT A TEMPERATURE OF AT LEAST 400*C. UNDER A PRESSURE OF AT LEAST 200 ATMOSPHERES, AND SEPARATING AS THE RESULTING PRODUCT AN ALKALI METAL TITANATE IN THE FORM OF WATER-INSOLUBLE, NON-HYDRATABLE, FLEXIBLE FIBERS.

12. AS A NEW INORGANIC FIBROUS MATERIAL, ALKALI METAL TITANATE CRYSTALLINE FIBERS EACH HAVING A RATIO OF LENGTH TO WIDTH OF AT LEAST 10:1, AND EACH BEING SUFFICIENTLY FLEXIBLE TO BE FELTED, SAID FIBERS BEING INSOLUBLE IN WATER, NOT ABSORBING WATER OF CRYSTALLIZATION TO FORM A HYDRATE, AND HVING THE GENERAL FORMULA M2O9(TIO2)N, WHEREIN M IS AN ALKALI METAL HAVING AN ATOMIC NUMBER OF AT LEAST 11 AND N HAS A VALUE OF FROM 6 TO 7.