US2082936A - Detergents and method of making the same - Google Patents

Description

Patented June 8 1937 7 Claims. This invention relates to detergent compositions as well as to a method of producing them. More specifically it relates to detergent compositions which include a mixture of crystalline alkali metal silicate such, for example, as sodium metasilicate and a bdr'on containing compound. as well as to a method for producing them. i

Before proceeding with a detailed description of the nature and objects, of the invention I should like to point out that ordinary borax (Na2B4O1.10H2O), while long used in industry as a fungicide and bactericide, is somewhat too weak an alkali to be, used as a general detergent. In the citrus industry, therefore, it has heretofore been customary, by way of example, first to wash the fruit in an alkaline detergent solution in order to remove adhering dirt, after which 'it. is often further treated by dipping it into a solution of ordinary borax (N8.2B407 .10H20) in order to inhibit the growth of blue mold and other fungi upon the skin of the fruit during storage. This procedure, of course, involves two separate steps, first the cleaning step and then the disinfecting step. Similar situations arise in other industries.

I should also like to point out that the alkali metal silicates including particularly sodium metasilicate, while good detergents, are somewhat too caustic for uses which bring-them into contact I with citrus or pomaceous fruits or-with human ties of borax can be combined with the detergent properties of theialkali metal silicates, particularly sodium' metasilicate, to form a composition of matter which can be used for carryingout both washing and sterilizing operations simultaneously and the primary object of my invention is to provide a composition of matter of this nature which I shall term a fungicidal detergent.

With the foregoing in mind the objects of my invention may be stated in greater detail as follows: (1) 'the provision of a fungicidal detergent 45 which possesses not only the high detergent value of sodium metasilicate, but also the fungicidal r and bactericidal properties of borax; (2) the provision of a.detergent of the character specified which is extremely mild inits actidn on the skin 50 and much less corrosive in its effect on the so- 1 called softer metals such; for example, as aluminum and tin; (3) the provision of a novel method for the production of my improved composition of matter by means of which the mixture of the 55 ingredients is so thoroughly and intimately ef- PATENT,

DETERGENTS AND METHO OF MAKING THE SAME Y OFFICE Chester L. Baker, Berkeley, Calm, assignor to Philadelphia Quartz Company, Philadelphia,

Pa a corporation of Pennsylvania No Drawing. Application June 21, 1934,

Serial No. 731,642

fected as to preclude all possibility of segregation or'separation of the constituents; (4) the provision of a. product of the character described 7 which will remain stable in storage and which can a as limitations upon the generic nature of the invention inasmuch as it will be perfectly clearto those skilled in the art that many variations might be adopted without departing from the spirit of the invention.

When ordinary borax. (Na2B4O'L10H2O) is mixed with any one of the hydrates of sodium 1 metasilicate, the mixture, after a comparatively short time, becomes either, fluid or gummy in character and, therefore, unsuitable as an article of commerce. I have-discovered, however, that ii! the lower hydrate of sodium tetraborate, NazB4O'L5H2O, is mixed with a compatible hydrate of sodium metasilicate such mixture will remain substantially dry and 'stable in storage and also that if ordinary borax is first converted into sodium metaborate, such metaborate may be mixed with sodium metasilicate to produces. i

dry stable product providing compatible hydrates of these two salts arechosen for use in the mix ture.

It will be obvious that the requirements for stability in the several different mixtures are dependent upon the individual peculiarities of the crystalline compounds comprising a given mixture, the melting points and transition. points of the various possible hydrates, possible chemical reactions with each other, and conditions requi-ij site for phase equilibria. ,I have found, however, that the following combinations yield substantially dry, stable mixtures;

- able method with or more parts of sodium and tetraborate pentahydrate, Na2B4Om5H2O, such mixtures will remain stable solong as they 2 are protected from the air. While such mechanical mixtures constitute an important part of my invention, I prefer wherever possible to crystallize the two salts together in the form of a hard 5 brittle cake which can then be ground to a granborate which may be ground to what is an apparently dry, stable, granular or. powdery condition.

A simultaneously crystallized mixture of this nature may be obtainedby proceeding in general as follows:.

A mixture is prepared which is calculated to satisfy the chemical requirements of the desired composite product and crystallization of this mix- .ture is effected in a manner'which-will convert the entire mass into a hard brittle cake which can be ground to produce a stable granular product.

However, in some instances this end cannot be directly'attained since the temperature of the mixture as well asthe composition of the liquid phase at any moment will determine the particular salt or salt hydrate which is likely to crystallize' out so that unless especial precautions are employed, which will.be described hereinbelow, the resulting product may not always be the desired one. -In general, it maybe stated that the mixture should becaused to crystallize "within the temperature range of conditions where the desired crystalline compounds are in equilibrium and where they will crystallize from the pre- 40 pared mixture without the formation of undesired crystalline compounds. If sufflcient attention is not given to these details the resulting product will not be of the character desired. For

instance, if one of the salts were to crystallize with a lower degree of hydration the product would containuncrystallized water and would be soft and fudge-like in consistency instead of hard and brittle as desired. v To more fully illustrate the difiiculty just. discussed, I should like to point out. that if one mixes directly a solution of silicate of soda with sufiicient caustic soda and borax and evaporates sufiicient water so that the resultant solution satisfies the chemical requirements of a mixture M50 parts of sodium metaborata-tetrahydrate (NaBOzAHzO) and 50 parts r sodium metasilicatenonahydrate (NazSiO:.9I-I:O) and then at-' tempts ,to crystallize the mass byseeding, cooling and vigorous agitation, he will likely crystallize lower hydrates than those desired, so that the product will be soft in consistency like fudge candy instead of hard and brittle. Such a'pro'duct, of course, cannot be ground to a dry, freeflowing condition, and is, thereforeynot suitable for commercial purposes. Furthermore, it'is not stable. The reasonfor the undesired results mentioned in the preceding paragraph is to be found in the fact that there exists a transition'p'oint between a temperature below 55"'C. if 'NaBOzAEO is to. be obtained. Likewise, there is a transition, point production of an intimate mixture of. sodium.

metasilicate nonahydrate and sodium metaborate tetrahydrate. I Wish it to be distinctly understood, however, that I do not wish to be limited to the exact proportions or procedure outlined as it is-quite obvious that certain variations may be adopted without departing from the spirit or scope of the invention.

Example for the preparation of an intimate mixture of Na2SiO3.9HzO and NaBO2.4H2O

To 428 parts by weight of a solution of silicate of soda containing 18.5% NazO and, 37% SiOz is added 148.2 parts of caustic soda containing 76% NazO and then 250.3 parts of water is added. The solution thus formed should preferably be cooled sufliciently so that upon the addition of 173.5 parts of borax (NazB4Om10H2O) the tem perature of the mass is below 46.4 C. The mass is then seeded with 25 parts of crystalline NaBOa.4HzO and '75 parts of crystalline Na2SiOs.9HO."

The mixture is then agitated and cooled until it becomes quite thick in consistency. During this process, care must be taken to keep the tem- I perature of the mass below 46.4 C. The'thickdrates.

I have further discovered that the desired mixture may be prepared if a solution of the desired sodium metasilicate is first prepared and crystallization thereof initiated and promoted to some extent before the required borax and caustic soda are added. ,An example of this method is given below.

Example for the preparation of an intimate mid:-

ture of NazSiO3.9H2O and NaBOz.4HzO where crystallization of the sodium metasilicate is begun before the borax and caustic soda are added 583 pounds of a solution of silicate of soda containing 29 percent S102 and 8.9 percent M is run into a vessel which is equipped with a heavy agitator and a jacket for heating orcooling.

162 pounds of caustic soda is then added, brought.

into solution, and the solution thus formed is cooled to 45 C. 50 pounds of NaeSiOailmO is then added and the mass cooled and agitated until it becomes fairly thick and opaque. This indicates the formation of crystals of NazSiOaQHaO. At this stage is added a mixture comprising 592 pounds of borax and pounds of caustic soda.

. 9,082,986 r a p 'and cooled until crystallization has well started In some cases it may be necessary to add this mixture a little at a time, as it is important that the temperature does not go above 46.4 C.

at this stage. When the addition is complete, at

Method of preparing a mixture of NazSiOs.9HzC' and NaBOzAH'zQ To 2250 grams of a solution of silicate of soda containing 28.82% S102 and 8.84% NazO are added 620 gramsof caustic soda containing 76% NazO and 630 'gramsof water. The solution formed is then cooled to any convenient tem--' perature below 55 .C. At a temperature above 55 c. NaBOzAHzOtransforms.intoNaBOaZHzO I and since the former compound is desired, it is necessary to maintain the temperature below 5 55 C. To the solution is then added 1850 grams of borax (Na2B4Om10H2O) and 390. grams caustic soda containing 76% NaaO. This addition is brought into solution by stirring, care being taken to prevent the temperature rising above 55 C. The mass is then placed upon the two primary rolls of anink grinding roll mill and 100 grams of Na2SiOa.9H2O and 100 grams of NaBOa'AHzO added for seed. The mixture is ground for about one minute and then discharged from the machine as a white,- opaque material which solidifies almost immediately to a' hard brittle product which when ground will remain dry, free-flowing and stable .upon storage. The product will consist of a definite mixture of NaBOzAHaO and NacSiOaBI-IzO.

In the above example it is. advisable to continuously cool the rolls of the mill by artificial means so that the temperature of the mass will be brought to and maintained at a temperature below 46.4" C. and-thus insure the crystallization of the desired hydrates as well asfacilitating crystallization by removing the heat liberated I In the preparation of an intimately crystallized mixture of sodium metasilicate pentahydrate (NazSiO35Hz0) and sodium metaborate dihydrate (NaBOz.2HzO) it is of course, necessary that crystallization be effected below the melting point of NazSiOa5HzO (72 C.) as well as' below the transition point between NaBOa2HzO and NaBOaI-IzO. This transition point is not accurately known, but in practice good results may be had by preparing the mixture to'be crystallized at a temperature below 65 C. By way of example I might prepare an intimately cry'stallizedmixture as follows:

To 1241parts by weight of a solution of silicate of soda containing 29% SiOz and 8.9% NazO is added 344 parts of caustic soda containing 76% No.20 and the solution thus formed evaporated to a weight of 1272- parts. The hot solution should test just under 63 Baum and should have a. chemical composition corresponding to that of the formula Na2SiO3.5HzO. This solution is then". cooled to a temperature of 72 or under, seeded 75 with 50 pouhds of NazSiOa.5l-Iz0' and agitated and the mass has become white and opaque. 400 parts of finely ground nanoazmo is then mixed in and mixing and cooling continued as long as practicable. It may then be discharged into any suitable container. Upon cooling, the mass" will be found to be hard and brittle and may be ground to a dry, free-flowing and stable condition.

.While the above example represents my preierred method for'making an intimately crystallized mixture of naisioasmo and NaBO2.2H2O, itis possible to crystallize the two compounds more or less simultaneously as set forth in the.

following example. a

Example for the preparation of an intimately crystallized mixture of NazSiOmHzO and NaBQaZHzO To 1241 parts by weight of a solution of silicate or soda containing 29% S102 and 8.9% NaaO is added 344 parts of caustic soda containing 76% NazO and the solution thus formedevaporated to a weight of 1272 parts. The hot solution should test just under 63 Baum and should have a chemical composition corresponding to that, of the formula Na2SiOa.5I-I2O. This solution is then cooled to 'a temperature of 70 C. or under, seeded with 50 pounds of Na2SiO3.5HzO and agitated while maintaining the temperature above 55' C. When the mass has become quite thick and opaque, one should add 36 parts of water, 81.5

parts ;of caustic soda containing 76% NazO and 291 parts of NazBrOmiiHzO. When this has been well mixed-in, the temperature is adjusted if necessary to a value between 55 C. and.'l2 C. 50 partsrof NaBOz.2HzO are then added for seed, and mixing with cooling continued as long as practicable. The doughy mass is then discharged from the mixer and allowed to cool. When cool it will be found to be hard and brittle and. may

be ground .to a stable granular or powdery condition. I v I By following the general method of the foregoing examples, it is quite possible toprepare mixtures with widely difierent proportions of sodium metasilicate to sodiummetaborate. Furthermore,the raw materials employed in the production of the desired products may have diiferent characteristics, 1. e:, the silicates of soda may vary and also the borates. In addition the desired end product may be obtained through the use of boric acid and caustic soda with the requisite amount of water instead of with the borax specified. Many other variations of a similar nature forth will occur to those skilled in theart,

In connection with all of the examples set above I wish to direct attention to the fact that it may not always be necessary to resort to seeding in order to initiate crystallization because in some instances I have found that crystallization begins spontaneously when the proper condi tions are established.

I claim:- 1'. An alkaline detergent mately crystallized mixture of sodium metasilicate .no nahydrate and sodium metaborate tetrahydrate.

2. An a aline detergent-comprising an intimately crystallized'mixture of sodium metasilicomprising an' inti- 45 borate tetrahydrate 15 4. A method of preparing an intimately.

. crystallized mixture of sodium metasilicate.p.enta-- hydrate and sodium metaborate dihydrate which includes the following steps:

(a) Preparation of a solution having the chem- 20 ical composition corresponding to the formula NazSiOafiI-IzO.

(b) Cooling the solution to a temperature of 70 C. or slightly thereunder and seeding with crystalline NazSiOa.5I-Iz0.

Adding sodium tetraborate and caustic soda in the proportions required to form the desired sodium metaborate dihydrate.

(d) Holding the temperature of the mass between a temperature of 55 C. and 72 C. and

I 30 efi'ect ing crystallization thereof.

5. A method'of preparing a mixture of sodium metasilicate nonahydrate and sodium metaborate tetrahydrate which includes the following steps:

(12) Preparation of a solution calculated to satisfy the chemical requirements of sodium metasilicate nonahydrate. f

(b) Cooling the solution and initiating crystallization of sodium metasilicate nonhydrate.

40 (0) Adding the ingredients required to produce the composition of the desired :mixture with further cooling, if necessary, to bring the temperature below 46.4 C., and

(d) Initiating crystallization of sodium m'etawhile maintaining the temperature below 46.41 C.

6. The method of preparing a dry stable mixture of sodium metasilicate pentahydrate and sodium metaboratedihydrate which comprises the following steps:

(a) Brepai-ation of -a solution calculated to satisfy the chemical requirements of. sodium metasilicate pentahydrate;

(b) Cooling the solution to and maintaining it at a temperature between about 55 C. and 70 C.;

(c) Initiating crystallization of sodium metasilicate pentahydrate and permitting it to continue until the mass becomes fairly thick;

(d) Adding the ingredients required to produce the composition of the desired mixture accompanied with further cooling, if necessary, to maintain the said temperature;

('e) Initiating crystallization of sodium metaborate dihydrate; and

(f) Agitating and permitting the entire mass to cool and'form a hard, grindable cake.

7. The method of preparing a dry, stable mixture of a desired hydratedsodium metasilicate and a compatible hydrated sodium metaborate as herein disclosed which comprises the following 1 steps:

(oi-Preparation of a solution calculated to satisfy the chemical requirements-of the desired sodium metasilicate hydrate;

(b) Initiating crystallization of the said sodium metasilicate hydrate and permitting it to continue until the mass becomes fairly thick;

(0) Adding the ingredients required to produce the composition of the desired compatible sodium metaborate hydrate while cooling, if necessary, to maintain the temperature below the melting point of the desired sodium metasilicate hydrate; and

(d) Initiating crystallization of the compatible sodium metaborate hydrate with further cooling, if necessary, to maintain the temperature below the melting temperature of the said crystalline metasilicate and also below the transition point between the said compatible crystalline metaborate and the crystalline metaborate of next higher melting temperature.

cnns'rnn L. BAKER.