Patented June 12, 1951 r 2,556,953

UNITED STATES PATENT OFFICE 2,556,953 BARIUMPERBORATE James H. Young, Niagara Falls, N.Y., assignor to E. I. du Pont de Nemours & Company, Wi mington, Del, a corporation of Delaware No Drawing. Application July 9, 1947, Serial No. 59,915 4. Claims. (C. 252-363.5) 2 This invention relates to the preparation of above. Still other objects will be apparent from barium perborate and more particularly to a form the following description of my invention. of barium perborate which is readily dispersible The aforesaid objects may be attained in ac in organic compounds. cordance with the present invention by reacting It has been proposed to incorporate in vinyl a water soluble barium salt with an inorganic per resins, such as polyvinyl chloride, solid metal per oxide and a soluble borate in an aqueous alkaline borates to act as stabilizers. Barium perborate solution at a temperature of 40 to 60° C. and re is Well suited for this purpose. However, to obtain moving the resulting precipitated barium per the maximum advantage of the barium perbo borate. I have discovered that the reaction tem rate and to avoid impairment of physical proper O perature is an important factor in producing a ties of the vinyl resin, it is desirable to utilize a grade of barium perborate which is readily dis grade of perborate which will readily disperse in persible in organic substances to produce clear organic compounds to produce highly stable dis dispersions. In order to attain this result I found persions. In some cases relatively clear, trans that it is necessary to maintain a reaction tem lucent to transparent dispersions are desirable. 15 perature not lower than about 40° C. At lower In One method for incorporating barium perbo temperatures, the reaction to form barium per rate in a vinyl resin, the perborate may be dis borate proceeds readily, but the resulting precipi persed in an organic compound which is a plasti tated product is not readily dispersible in organic cizer for the resin, e. g., tricresyl phosphate, and substances to produce stable dispersions. Attem the resulting dispersion incorporated in the resin 20 peratures above 60° C., suitable dispersible prod in a conventional manner. Dispersions may also lucts are obtained, but at Such elevated tempera be made in plasticizers or mixtures of resins and tures undue decomposition of peroxide and per plasticizers which are normally liquids or nor borate occur so that it is difficult to obtain a mally solids; in the latter event, the perborate product having a suitable amount of active oxy is dispersed in the molten plasticizer or mixture. 25 gen. It has long been known that barium perborate The following examples illustrate specific can be made by reacting a barium salt with an modes of practicing the invention. alkali metal perborate. In such preparations Water soluble barium Salts are used and the re EXAMPLE 1. Sulting perborate generally is insoluble and is 3 200 g. of borax (Na2B4O7.10H2O) and 37.4 g. obtained as a precipitate. However, barium per of Sodium peroxide (Na2O2) Were mixed and add borate produced by methods heretofore known is ed to 4 liters of water with stirring. 112 g. of generally difficult to disperse in organic sub 30 vol. (35.0%) H2O2 solution was then added. stances and generally fails to produce the clear To this solution at 59 C., a solution of 244 g. of dispersions which are required for the stabiliza BaCl2.2H2O was added with stirring over a period tion of vinyl resins as described above. For ex of 7 minutes. Stirring was continued 1 hour. The ample, a process has been proposed for the prep slurry was then filtered and washed thoroughly aration of Ba (BO3)2.7H2O (Berichte 31, 954 With water and dried in a brisk stream of air (1898)). This heptahydrate melts and decom at 40-50° C. for 24-48 hours. 271 g. of dry prod poses readily and is unfit for storage. Its dis 49 uct was recovered, which was found to be a per persions in organic compounds contain undesir borate that can be designated as barium meta ably large amounts of water and are cloudy. It is borate perhydrate-hydrate having the formula expensive to process because very large amounts shown below: of water are necessary to produce very small Analysis (per cent by Deight) weights of product. This perborate does not give clear dispersions in vinyl resin plasticizers or ActiveO Approximate Com other organic compounds. BaO B2O3 H2O2 HO position Calculated An object of the invention is to produce a grade, of barium perborate which is readily dispersible Percent Percent Per cent Percent Per cent in organic compounds and in particular so as to 50 produce relatively clear dispersions. The inven tion includes an improved novel process for pro ducing barium perborate and, as a new composi The dry product is a fine powder having good tion of matter, a particular grade of barium per stability at 25-30 C, and fair stability at 50° C. borate which meets the requirements mentioned 55 Tests were made by mixing it with tricresyl

2,556,958 3 4. phosphate. The product dispersed quickly and example, the preferred proportions of the react completely to give good, stable dispersions in pro ants will be approximately: portions of 10 to 40% by weight. Moles EXAMPLE 2 Sodium peroxide ------1. Hydrogen peroxide ------1.5 to 2 Proceeding in accordance with Example 1, a Borax ------1 to 1.1 barium meta-borate perhydrate-hydrate was Water ------100 to 400 precipitated. When precipitation had been com Barium Salt ------18 to 2.2 pleted, 2 cc. of tricresyl phosphate was added 10 and thoroughly stirred into the slurry. The The amount of barium salt added to the reaction batch then was filtered, washed and dried for 16 mixture is not critical, provided sufficient is added hours at 53° C. and for 6 additional hours at 60 to cause precipitation of barium perborate at the C. 273 g. of dry product containing 7.5% active reaction temperature. I prefer to add approxi oxygen was recovered. This was a fine powder, mately the theoretical proportion of the barium the particles of which were coated with tricresyl salt, that is, about 2 moles, per mole of borax phosphate. reacted, or a small excess thereover. If leSS than the theoretical amount of barium salt is added, Tests with tricresyl phosphate dispersions as the yield based on active oxygen is correspond in Example 1 showed an exceptionally rapid wet ingly decreased; however, a Small annount of through and particularly clear dispersions, in pro 20 portions of 10 to 50% by weight of the barium barium salt, as low as 0.1 mole, will cause some perborate. product to precipitate. If more than the theo retical amount is added, the excess barium Salt The formula, of the product as shown in Ex appears in the filtrate after removing the pre ample 1 indicates a perhydrate, rather than a cipitated product. true persalt in which the active oxygen is part 25 Also I prefer to utilize 100-400 moles of water of the borate anion. However, I have not deter and a sufficiently high temperature (at least 40 mined whether or not the product is a true per C.) so that sodium perborate will not precipitate. salt in which the active oxygen is contained in Higher operating temperatures also minimize ex the borate anion or whether it is a perhydrate cessive hydration. having the active oxygen in a hydrogen peroxide 30 molecule which is combined with the borate, as Washing with water to remove soluble Salts is shown in the above formula. It is also possible preferred. Generally, 10-20 washings will suf that this product may be a mixture of barium fice to remove soluble salts to a desirable level of perborates (or barium borate perhydrates) hav 0.5-1.0%. ing different degrees of hydration. In any event, Drying is not critical. It may be conducted on if the product be considered a borate perhydrate, 35 tray driers, spray driers, rotary driers or on drun it has about 1.5 mole combined H2O2 and 1 mole driers. For tray and rotary drying, a tempera combined H2O (water of hydration) per barium ture of 40-70° C. and thin films are preferred. atom. If it is considered a true perborate (bari For more rapid drum drying, temperatures of um Salt of the hypothetical HBO3) it has about 130-40° C. are Suitable. - - - 2.5 moles of combined H2O per barium atom. 40 Contamination with large amounts of heavy In practicing the invention the proportions of metal Salts should be avoided. Suitable process borax, sodium peroxide and hydrogen peroxide ing equipment may be wood, glass, stainless steel may be varied considerably without departing Or Monel. " . - from the scope of the present invention. In place The novel barium perborate of my invention is of Sodium peroxide I may use equivalent quan 45 not limited to the product of Example 1, but tities of hydrogen peroxide and a suitable alka products containing somewhat more and less of li, Such as caustic soda. The invention is also active oxygen and of water of hydration may be not restricted to using caustic soda, as the alka obtained. The composition of such products is line material, but other alkalies, for example, conveniently expressed by a perhydrate formula, the hydroxides of potassium, lithium, rubidium 50 like that of Example 1, or the product may be and cesium, may be used as well. Likewise, other considered to be a mixture of barium perborate alkali metal peroxides and borates may be used hydrate and barium meta-borate (which may or in place of sodium peroxide and borax. As will may not be hydrated), which hydrated com be obvious to chemists, the invention is not re pounds could be expressed by formulas such as stricted to borax or other alkali metal borates, 55 Ba(BO3).nH2O and Ba(BO2)2.mH2O, where n but equivalents such as metaborates and boric and m are integers. For convenience, I prefer to acid can be used instead, and the amount of al express the composition of the novel products by kali added as alkali metal peroxide or hydroxide the perhydrate formula: WEary depending on the alkalinity of the borate 60 USec. Ba(BO3)2.a.H.O.gHeo The composition of the barium perborate pre The active oxygen content and degree of hydra cipitate will depend in large measure on the pro tion may vary as expressed by this formula when portions of the reactants utilized and the reac ac and y represent any quantities within the limits: tion temperature. In carrying out the reaction With Sodium peroxide, hydrogen peroxide and 65 for ac: from 1 to 2 borax, preferably the reaction mixture will con for y: from 0 to 2 tain at least one mole of borax for each mole of Thus the composition may vary from the Sodium peroxide. Generally, I prefer a 2 to 10 monoperhydrate: Ba (BO2)2.H2O2 to the diper mole-per cent excess of the borax. The reaction 70 hydrate dihydrate: Ba (BO2)2.2H2O2.2H2O. mixture also preferably will contain at least 1.5 These variations in composition can be ex moles of hydrogen peroxide per mole of sodium pressed in terms of the conventional perborate peroxide and this may vary from 1.5 to 2 moles. formula Ba(BO3)2 thus: when ac is 1 and y is 0. The Water present may vary from about 100 to the product is an equimolar mixture of: 400 moles per mole of sodium peroxide. For 75, Ba(BO3) anho 2556;958. 5 6 and phosphate and the like; otheresters of phosphoric acid, including alkyl, alicyclic and aralkyl esters; Ba(BO2)2.m.H2O diphenyl propane, monomethyl toluene, Sulfon where n and m each may be 0,1 or 2, and the Sun amide and thiocarbanilide. Various other Com of n--m equals 2. pounds not specifically listed herein, which are Whena is 2 and y is 2, the product is the per known to be suitable as vinyl resin plasticizers borate tetrahydrate: are likewise included. Such compounds, many of which are liquids, are characterized by rela tively high boiling points (above 100° C.) and by In other words, the ratio of barium, borate to O the fact, that they can be mixed with vinyl resins combined hydrogen oxides (H2O2 and H2O) in the to form homogeneous plastic compositions. product may vary from 1:1 to 1:4, Barius perborates made as herein described, The variation in active oxygen content ex having a fineness of about 100 to 200, mesh size, pressed in the above formulas, i.e., a variation of are characterized by the ease with which they about 5 to 10% by weight in the product, may be 5 may be dispersed in liquid organic compounds, accomplished by correspondingly varying the ac including the above mentioned plasticizers, by tive oxygen (peroxide) concentration in the re merely stirring, to produce relatively stable dis action mixture. The variation in the degree of persions. When the refractive index of the or hydration of the product may be accomplished by ganic compound is equal, or approximately equal varying the reaction temperature and drying 20 to that of the perborate, Such dispersions are temperature, increasing temperatures favoring substantially clear. Other forms of barium per lower hydration. borate, ground to an equal state of subdivision, A preferred mode of practicing the invention I have found form distinctly less stable disper is illustrated by Example 2, wherein organic-liq sions in the same organic compounds and form uid, e. g., tricresyl phosphate, is added to the 25 cloudy dispersions when the organic compound precipitated product before it is, removed from has substantially the same refractive index. the reaction mixture. The result, of Such opera The term “vinyl resin' is used herein to de tion is to coat, particles of the precipitate. with the note polymers and copolymers of monoolefinic organic liquid, which coating. I have found facili Compounds having the vinyl group (CH2=CH-) tates dispersion in the same, or other liquid or 30 and derivatives thereof, e.g., chlorovinyl com ganic compounds compatible therewith. Several pounds. Examples are the polymers and copoly alternative methods may be utilized thus to coat mers of vinyl carboxylates, e.g., vinyl formate, the precipitate with a liquid organic compound, vinyl acetate, vinyl propionate and vinyl benzo in all of which the organic compound is brought ate; Vinyl halides, e. g., vinyl chloride and vinyl into contact with a wet precipitate. The organic 35 bromide; and vinyl aryls, e.g., styrene. The term compound may be added with the other ingre “vinyl resins' also includes products such as poly dients to the reaction mixture so that it is pres vinyl acetals, polyvinyl ethers, polyvinyl alcohols ent when the reaction forming the barium per and the like. - borate occurs. When this method is utilized the While my invention is particularly useful for organic compound selected must of course be one 40 preparing dispersions of barium perborate in that is not readily oxidized by the peroxide pres Vinyl resin plasticizers and hence in vinyl resin ent, under the reaction conditions. Another Compositions, other uses for the invention will method is that shown in Example 2, wherein the be apparent. Thus the herein described im organic compound is added after the barium per proved method for making barium perborate and borate has precipitated but before it has been 45 the product thereof make available a peroxygen separated from the reaction mixture. Substan product of relatively high oxygen content and tially the same result will be obtained by first fil good stability during storage, that may be used tering or separating the precipitated perborate for various purposes where active oxygen com from the reaction solution, then mixing the or pounds are generally applied, e.g., as polymeriza ganic compound with the wet precipitate and sub 50 tion catalyst, bleaching agent, oxidation of chem sequently drying, preferably with agitation. ical compounds, and the like. In many of such While tricresyl phosphate has been added to uses, the improved dispersibility of the product coat the precipitate and improve its dispersions in organic compounds is advantageous, for ex other water-insoluble non-volatile organic liq ample, in bleaching oils, fats and waxes, in uids or molten organic compounds will also serve. 55 Oxidation reactions and in many polymerization For this purpose I prefer to choose an organic reactions. compound which is suitable as a plasticizer for I claim: a vinyl resin. The amount of Such organic com 1. A composition of matter comprising a stable, pound may be varied from about 0.2 to 5% by homogeneous, substantially clear dispersion of a weight. About 1%, based on the Weight of the 60 barium perborate corresponding approximately dry barium meta-borate hydrate-perhydrate is to the formula: Ba (BO2)2.1.5H2O2.H2O, in tri suitable. cresyl phosphate. Barium perborates made as described herein 2. As a new composition of matter a Solid may be dispersed in the various organic com barium perborate composition which is disper pounds suitable as plasticizers for vinyl resins, in sible in tricresyl phosphate merely by stirring various proportions, up to 50% by weight, to give therein in proportions of 10 to 50% by weight to excellent dispersions. These include esters of produce a substantially clear dispersion, compris Organic acids such as phthalic, tartaric and Suc ing a dried precipitate of barium perborate cor cinic acids; the polyethylene glycol esters of the responding approximately to the formula, isomeric hexoic acids; and various glycol and 70 polyglycol esters of other fatty acids, e.g., glycerol esters, glycerol acetal esters such as butyralde each particle of which is coated with tricresyl hyde acetal of glycerol monoacetate and the like. phosphate. Other Suitable plasticizers are the aryl phos 3. The process for producing a barium per phates such as tricresyl phosphate, triphenyl is borate readily dispersible in an organic liquid

2,556,958 7 which comprises reacting together at a tempera mixing into the resulting slurry a small quantity ture of 40 to 60° C. a. water soluble barium salt, of tricresyl phosphate, then removing and drying borax, sodium peroxide and hydrogen peroxide the precipitate, and stirring the dried precipitate in water in the following proportions: with a sufficient quantity of said phosphate to Moles form a dispersion therein. Sodium peroxide------JAMES H. YOUNG, Hydrogen peroxide------1.5 to 2 Borax------1 to 1.1 REFERENCES CTED Barium salt------1.8 to 2.2 Water------100 to 400 () The following references are of record in the to form a precipitate of barium perborate cor file of this patent: responding approximately tothe formula: UNITED STATES PATENTS Ba (BO2)2.1.5H2O2.H2O Number Name Date s 999,497 Gruter ------Aug. 1, 1911 mixing into the resulting slurry a small amount 2,356,091 Roedel ------Aug. 15, 1944 of tricresyl phosphate which have boiling points 2,422,153 Nim Wegen et al. --- June 10, 1947 above 100° C., then removing and drying the precipitate. FOREIGN PATENTs 4. The process for making a stable, homoge 20 neous dispersion of barium perborate in an Or Number Country Date ganic liquid which comprises reacting together 193,559 Germany ------Oct. 14, 1903 at a temperature of 40 to 60° C. a barium salt, borax, and an adueous alkaline hydrogen per OTHER REFERENCES oxide solution in proportions equivalent to: Ser. No. 293,101, Nees (A. P. C.), published Apr. 25 27, 1943. Moles Mattiello: Protective and Decorative Coating, Sodium peroxide------1. vol. III, pp. 560 and 561. Hydrogen peroxide------1.5 to 2 Vinylyte Copolymer Resins for Surface Coat Borax------1 to 1.1 ing, published by Carbide and Carbon Chem. Co., Barium salt------1.8 to 2.2 30 N. Y., pp. 26 and 97. Water------100 to 400 Mellor: Treatise on Theoretical and Inorganic to form a precipitate of barium perborate cor Chemistry, vol. 9, p. 120 (1924). responding approximately to the formula: Gmelin-Kraut, 2.2 Handbuch der Organische Ba (BO2)2.1.5H2O2.H2O 35 Chemie, p. 99.