US2977314A

US2977314A - Borate-hypochlorite bleach

Info

Publication number: US2977314A
Application number: US824778A
Authority: US
Inventors: Stephen E Stephanou; Lawrence L Schwalley; Sam H Lee
Original assignee: United States Borax and Chemical Corp
Current assignee: US Borax Inc
Priority date: 1959-07-03
Filing date: 1959-07-03
Publication date: 1961-03-28
Anticipated expiration: 1978-03-28
Also published as: ES256927A1; BE587734R

Description

or w- BORATE-HYPOCHLGRITE BLEACH Stephen E. Stephanou, Santa Ana, Lawrence L. Schwalley, Whittier, and Sam H. Lee, Anaheim, Calif., assignors to United States Borax & Chemical Corporation, Los Angeles, Calif., a corporation of Nevada No Drawing. Filed July 3, 1959, Ser. No. 824,778

' 8Claims. Cl. 252-99 The present invention is a continuation-in-part of Serial No. 730,541, filed April 24, 1958, which was in turn a continuation-in-part of Serial No. 709,439, filed January 12, 1958, now abandoned.

This invention relates to new and novel compositions of matter and has more particular reference to boratehypochlorite bleach compositions and method for making the same.

It is well known that sodium hypochlorite containing materials have not previously attained commercial success as solid bleaches due to their extreme hygroscopicity and instability. Various methods for the manufacture of sodium hypochlorite in solid form have been described such as by mixing sodium hypochlorite solution with soluble anhydrous salts capable of taking their water of crystallization from the hypochlorite and of solidifying into a crystalline mass. We have found, however, that it is not possible to produce commercially acceptable products by these prior art methods since they are not sufiiciently stable.

We have found that when the alkali metal borates are reacted with hypochlorite with precisely controlled (OCl') B 0 and X 0 B 0 ratios, a solid bleach is produced having stability characteristics heretofore unattained by prior art compositions and methods.

It is therefore the principal object of the present invention to provide new and novel bleach compositions.

A further object of this invention is to provide a method of making ble'ach compositions having stability heretofore unattained by prior art bleach compositions.

A still further object is to provide a method of making the borate-hypochlorite compositions of the present invention.

Other objects will become apparent as the description proceeds.

To the accomplishment of the foregoing and related ends, the invention then comprises the features hereinafter fully described and particularly pointed out in the claims, the following description setting forth in detail certain illustrative embodiments of the invention, these being indicative, however, of but a few of the ways in which the principle of the invention may be employed.

Broadly stated, the present invention comprises a stable borate-hypochlorite bleach in a solid substantially dry form, said borate-hypochlorite composition having from 0.029 to 0.36 mole of (OCl-) per mole of B 0 and from 0.30 to 0.90 mole of X 0 per mole of B 0 where X is at least one material selected from the group consisting of the alkali metals, said X 0 comprising the titratable alkalinity of said borate-hypochlorite.

From the broadly stated paragraph it will be noted that the products of the present invention are defined as having critical (OCl"') B 0 and X 0 B 0 mole ratios. We have found that in order for borate-hypochlorite compositions to have low hygroscopicity, high stability and good bleaching properties, it is absolutely necessary to maintain from 0.029 to 0.36 mole of (OCl-) per mole of B 0 and from'0.30 to 0.90 mole of X 0 per mole of 2,977,3l4. Patented Mar. 28, 1961 ice B 0 Additionally, in the manufacture of the present compositions, as explained in the following examples, it will be seen that various soluble crystalline salts, such as the alkali metal chlorides and chlorates, can be present as impurities. However, it is to be completely understood that the X20 comprises only the titratable alkalinity calculated as X 0 from hypochlorites and borates. The titratable alkalinity is readily determined by potentiometric titration, a technique known to those skilled in the art.

Thus, it is again iterated that in order to obtain bleach compositions of low hygroscopicity and high stability the aforegoing ratios of (001-) B 0 and X 0 B 0 must be observed.

The present process involves the chlorination of an alkali metal borate or the addition of an alkali metal borate to sodium hypochlorite. The starting admixture can be prepared in a number of ways. For example, borax and caustic soda; sodium metaborate; potassium metaborate; borax and boric acid; lithium borate and borax; potassium borate and caustic soda; sodium metaborate and boric acid; boric acid and sodium or potassium hydroxides and various other combinations of these borates can be used in the production of the boratehypochlorite compositions of the present invention.

Using the above-mentioned borates and combinations thereof the present compositions can be prepared in a number of ways. In the preferred embodiment of our invention we first prepare sodium hypochlorite by chlorinating an aqueous solution of sodium hydroxide, make a slurry of the hypochlorite solution with a borate or combination of borates and then rapidly dry the resultant slurry. In this preferred embodiment of our invention we combine the ingredients in such proportion that the finished product has from 0.15 to 0.2 mole of (001*) per mole of B 0 and from 0.3 to 0.6 mole of Na O per mole of B 0 However, it is to be clearly understood that the present invention is not to be limited by the particular process used to make the borate-hypochlorite bleach, it only being important that the final product contains the proper ratio of ingredients and the drying step be completed as rapidly as possible.

The present bleaches can also be prepared by the dry admixing of borax and caustic soda and then chlorinating the admixture with chlorine gas. Thus the present materials can be prepared by the use of alkali metal hypochlorites or chlorine gas introduced into an aqueous slurry or dry powder. If direct chlorination is used the desired endpoint for chlorination can be achieved by continuous measurement of pH or by chemical analysis. The chlorine or chlorine containing material can also be calculated and added in the required total amount.

Also, if desired, more than one kind of alkali metal borate can be used to produce the present products. Sodium borate and potassium borate can be simultaneously chlorinated or a sodium borate can be reacted with NaOH and KOH and then chlorinated. However, it must be remembered, the total X 0 must remain in the range indicated above.

Any of the well-known methods of drying, such as vacuum oven drying, spray drying, drum drying, forced air drying, etc., can be used as long as such drying can be performed rapidly.

The present compositions may be either in crystalline or amorphous form. In any event rapid drying methods must be used to avoid decomposition due to overheating.

In the specification and claims the term dry is meant to convey a material having no free water. Thus, while our finished compositions contain varying amounts of chemically combined water or water of crystalliza- G17 tion, the material is dry in that there is substantially no free or chemically uncombined water.

A study of the chemistry involved in making the present products l r eal h t. the n ti m x ure. hetq e chlorie nation will always have a higher X 0 B 0 mole ratio than the finished product which comprises from 0.029 to 0.36 mole (.OCl) and from 0.30 to 0.9.0 m le X 0 per mole of B 0 be readily understood since the chlorination produces the formation of chlorides and chlorates in addition to the desired borate-hypochlorite. While it 'is' entirely true that the total alkali metal at the start of the reaction is' also present when the reaction is completed, neverthe z less the fact remains that neutral chlorides and chlorates are formed. This accounts for the final XgQ BQQ}, ratio. being lower than the starting ratio, sincethe chlorides and chlorates formed are not titratable alkali;

While as noted above, chlorides and chlorates are formed during the production of the borate-hypochlorite, they are not harmful to the finished product."

The invention will be understood in more detail from the examples which follow. The following formulationsare given only in the way of example andare. in no. way presented to indicate that the formulations of composi tions of this invention are limited to they cited examples:

Caustic soda (455' grams) was added to 520 grams of water and stirred until solution was complete. The stoichiometric amount of chlorine (390 grams C1 necessary to react with the NaOH to form NaQQl was. then passed into the solution. 1450 grams of borazr pent-ahydrate and 625 grams of boric acid were then slurried into. the sodium hypochlorite solution.

- The slurry was then pi t through a drum dryer. The drum dryer comprised two rolls having 0.010 clearance and an internal steam pressure of 60#/sq. in.-this'gave an external roll temperature of 153 C. The rolls were rotated 8 r.p.m. which gave a material contact time of 3.85 seconds.

The resultant product was a free-flowing stable solid bleach which analyzed about 6.6% available chlorine and had (001") B 0 and Na O B 0 mole ratios of 0.151 and 0.458, respectively.

Chemical analysis'of this product was as follows;

B rge Naoci 6.9 Neel 6-9 NaCl0 1.2 Na O' p 14.6 B 0 42.7 H2O 17.7

Using the technique. and equipment of .Example I Percent NaOCl A 7 7 8.9 NaCl 16.2 NaClO 1.4 Na O V 13.9. B203 51-: a i l The decrease in X 0 content will 4 III- Sodium metaborate (Na B O -4H O) (420 grams) was added to 615 mls. of water and the mixture stirred until solution was complete at room temperature. 65.5 grams of borax (Na B O .-10H O) were then added and stirred into the solution. In this case solution of the borax is not complete.

Dry chlorine (72 grams) was passedinto the mixture 7 while stirring (showed a pH of 9.3 upon 1:10 by weight bleach which analyzed 5.5% available chlorine and had ple of the supernatant liquid from the slurry showed a pH of 9.6-9.8 upon a 1:10 by weight dilution.

The slurry was dried as above and resulted in a freeflowing solid which analyzed 5.66% available chlorine and had final (OC1-) B 0 and Na O B 0 mole ratios of 0.148 and 0.66, respectively.

Sodium metaborate (Na B O -4H O) (6.788 grams) and potassium metaborate (,K B O -4H O') (821: grams) were s-lurried in. 9390 grams of water. The temperature. of the slurry was. maintained at below 26 C. and dry chlorine. was passed into the slurry until. the pH of the supernatant liquid was 9.35.

The chlorinated slurry was then dried in a direct gasfiredspray drier having an inlet temperature of 400 F.

and an outlet temperature of 243 F.

The resultant product was a free-flowingstable solid bleach which analyzed 3.0% available chlorine and final (OCl-) B 0 and Na O B 0 mole ratios. of 0.077 and 0.56, respectively.

The available chlorine content of the solid material of the above examples was measured by using the standard potassium iodide-thiosulfate titration.

1.0 gram of sample was added to l00 mls. of acidified KI solution. The liberated iodine was titrated with 0.1 N' standard sodium thiosulfate solution to-theusual endpoint (disappearance of yellow color) The percent of available chlorine was calculated as follows:

ml. thiosulfate X 0.1

Other modes of applying the principle of the invention may be employed, change being made as regards the details described, provided the features stated in any of the following claims or the equivalent of such be employed.

We, therefore, particularly point out and distinctly claim as our invention:

1. A composition of matter consisting essentially of a stable borate-hypochlorite bleach in a solid substantially dry form, said borate-hypochlon'te havingfrom 0.029. to

0.36 mole of"(OCl-) per mole of B 0 and from 0.30 to mole t X201 ma e. BzQn hfi X, v eas Q mate a s e t d r m. h group o s s o th alkali metals and said X 0 comprising the titratable.

alkalinity of said borate-hypochlorite composition.

2. A composition of matter consisting essentially of a stable borate-hypochlorite bleach in a solid substantially.

dry form, said borate-hypochlor-ite having from 0.15 to one material selected from the group consisting of the alkali metals and said X 0 comprising the titratable alkalinity of said borate-hypochlorite composition.

3. A composition of matter consisting essentially of a stable sodium borate-hypoohlorite bleach in a solid substantially dry form, said sodium borate-hypochlorite having from 0.029 to 0.36 mole of (OCl-) per mole of B 0 and from 0.30 to 0.90 mole of Na O per mole of B 0 said Na O comprising the titratable alkalinity of said sodium borate-hypochlorite composition.

4. The composition of matter of claim 3 wherein the (OCl-) B 0 mole ratio is from 0.15 to 0.2 and the Na O B 0 mole ratio is from 0.30 to 0.60.

5. The method of making a stable alkali metal boratehypochlorite bleach in a solid substantially dry form which comprises making an aqueous solution of caustic 'soda," chlorinating said caustic soda solution, slurrying into said chlorinated caustic soda solution at least one material selected from the class consisting of the alkali metal borates and boric acid and rapidly drying said slurry, said ingredients added in such proportion that the resultant product has from 0.029 to 0.36 mole of 001-) per mole of B 0 and from 0.30 to 0.90 mole of X 0 per mole of B 0 where X is a material selected from the group consisting of the alkali metals, and X 0 comprises the titratable alkalinity of said alkali metal borate-hypochlorite bleach.

6. The method of making a stable alkali metal boratehypochlorite bleach in a solid substantially dry form which comprises chlorinating an admixture consisting essentially of at least one material selected from the group consisting of the alkali metal borates and boric acid and at least one material selected from the group consisting of sodium hydroxide and potassium hydroxide and rapidly drying said chlorinated mass, said ingredients added in such proportion that the resultant product has from 0.029 to 0.36 mole of (001-) per mole of B 0 and from 0.30 to 0.90 mole of (OCl'-) per mole of B 0 wherein X is a material selected from the group consisting of the alkali metals and said X 0 comprises the titratable alkalinity of said alkali metal-hypochlorite bleach.

7. The method of making a stable sodium borate-hypochlorite bleach in a solid substantially dry form which comprises making an aqueous caustic soda solution, chlorinating said aqueous caustic soda solution, slurrying into said chlorinated caustic soda solution at least one material selected from the group consisting of the sodium borates and boric acid and rapidly drying said slurry, said ingredients added in such proportion that the resultant product has from 0.15 to 0.20 mole of (001-) per mole of B 0 and from 0.30 to 0.60 mole of Na O per mole of B 0 said Na O comprising the titratable alkalinity'of said sodium borate-hypochlorite bleach.

8. The method of making a stable sodium borate-hypochlorite bleach in a solid substantially dry form which comprises chlorinating an admixture consisting essentially of sodium hydroxide and at least one material selected from the group consisting of the sodium borates and boric acid and rapidly drying said chlorinated mass, said ingredients added in such proportion that the resultant product has from 0.15 to 0.20 mole of (001-) per mole of B 0 and from 0.30 to 0.60 mole of Na O per mole of B 0 said Na O comprising the titratable alkalinity of said sodium borate-hydrochlorite.

References Cited in the file of this patent UNITED STATES PATENTS

Claims

1. A COMPOSITION OF MATTER CONSISTING ESSENTIALLY OF A STABLE BORATE-HYPOCHLORITE BLEACH IN A SOLID SUBSTANTIALLY DRY FORM, SAID BORATE-HYPOCHLORITE HAVING FROM 0.029 TO 0.36 MOLE OF (OC1-) PER MOLE OF B2O3 AND FROM 0.30 TO 0.90 MOLE OF X2O PER MOLE OF B2O3, WHERE X IS AT LEAST ONE MATERIAL SELECTED FROM THE GROUP CONSISTING OF THE ALKALI METALS AND SAID X2O COMPRISING THE TITRATABLE ALKALINITY OF SAID BORATE-HYPOCHLORITE COMPOSITION.