Cleaning composition

Aug. 25, 1959

S. SPRING

CLEANING COMPOSITION Filed July 17, 1953

2,901,433

<img file="US2901433A_D0001.tif" />

.5

1.0 1.5 cc.Med.Wsc.Mineral Oil Solub./IOOcc.

2.0 2.5 grams Na₂S0₄

Inventor

Samuel Spring

By his attorneys

United States Patent Office

2,901,433

Patented Aug. 25, 1959 ·

2,901,433

CLEANING COMPOSITION ⁶

Samuel Spring, Philadelphia, Pa., assignor to Pennsalt Chemicals Corporation, a corporation of Pennsylvania

Application July 17, 1953, Serial No. 368,771

Claims. (Cl. 252—118)

This invention pertains to a cleaning composition of 15 matter and particularly to a composition of matter for removing greasy soils and soils having mixed oily and inert particulate or fibrous ingredients.

In many industries, it is necessary to clean surfaces of accumulated soil which is partly grease, and partly 20 dry dirt. One example is the railroad industry where locomotives and cars must be cleaned of a soil including fuel and lubricating oils, coal dust, and ordinary dirt.

Other common soils especially resistant to many conventional cleaners, are buffing compounds and heat- 25 treating oils which have been partially carbonized.

In various industries, workers’ hands are often soiled by mixtures of grease and inorganic dirt which cannot be removed with conventional soaps and hand cleaners. Obviously, in such cases, the type of cleaner which can ³θ be employed is limited by the sensitivity of the human skin to strong reagents.

Neither organic solvents alone, nor conventional soaps or alkaline washes alone have proved suitable for such cleaning, and many proposals have been made for clean- ³⁵ing solutions which would combine the characteristics of organic solvents and conventional soaps.

In any cleaner of the type adapted to remove grease and oil, together with other soils, an important aspect of the cleaner is the amount of grease or oil that it can ⁴⁰solubilize, i.e. hold in the body of the cleaner in a homogeneous form. It is characteristic of the cleaners herein described that after solubilization, soil and cleaner are readily removed by a water rinse.

It is an object of the present invention to provide a cleaning composition compounded of materials moderate in cost, which will readily remove greasy soils and soils containing both grease and inert particulate matter.

It is also an object of the present invention to provide ₅₀a cleaning composition capable of solubilizing large quantities of oil and grease.

Another object of the present invention is to provide a cleaning composition which can be used on the human skin without undue irritation. ₅₅

According to the invention, the above and other objects ° are obtained by formulations which basically comprise a soap, water, a weak organic acid, and a neutral salt. If it is desired that the composition be clear an alcohol is also added, and the prepared compositions, according _fi0to the present invention, contain an alcohol. °

An outstanding feature of my invention is the discovery that in such systems, a synergistic relationship exists between the organic acid and the neutral salt, which makes it possible for formulations according to the invention to dissolve large quantities of oil or grease. By means of this relationship, relatively small quantities of the novel formulations may be applied to soiled surfaces, where they function to dissolve grease or oil, permitting the latter, together with particulate dirt, to be rinsed off γη with a water spray or stream. ‘^υ

The soap is present in a proportion between about 1 % and about 50%, inclusive, on the weight of the composition, preferably between about 3% and about 25%, inclusive.

The weak organic acid comprises between about 1% and about 50%, inclusive, preferably between about 2% and about 25%, inclusive, of the weight of the composition.

The neutral salt comprises at least 0.05% of the weight of the composition and may be present in an amount up to and including the saturation point of the composition for the salt. It will be understood that the amount of salt. required to reach saturation will depend on the particular salt employed and the other components of the composition. Preferably the salt comprises between about 0.1% and about 1.0% inclusive of the weight of the composition.

The composition includes from about 5% to about 80% water, and preferably from about 10% to about 60% water.

It is also desirable, although not essential to the invention; in its broadest aspect, that the weight ratio, weak organic acid to soap, be between about 0.3 and about 2, inclusive, and preferably between about 0.5 and about 1.2, inclusive.

As previously stated it is generally desirable to also include an alcohol in the composition. When present, the alcohol will compri:e between about 0.5% and about 20%, inclusive, of the weight of the composition, preferably between about 2% and about 15% inclusive.

As pointed out above, the outstanding feature of the present invention is the discovery that a synergistic relationship exists between the fatty acid and the neutral salt, in a system comprising these substances together with soap and water. This synergism permits the compositions of the present invention to solubilize substantially larger quantities of grease or oil than could be solubilized by a system wherein either the fatty acid or neutral salt is present without the other. The invention in its broadest aspect, therefore, includes a composition having the above mentioned ingredients. It has been found, however, that for many applications it is desirable to include in the formulation quantities of an organic solvent.

The invention, therefore, further includes compositions comprising a soap, a weak organic acid, a neutral salt, water and an organic solvent with or without an alcohol. In general, where the solvent is included it comprises from about 6% to about 90%, inclusive, of the composition, and preferably from about 10% to about 80%, inclusive.

The invention besides including compositions that contain no organic solvent and are used as such, also includes concentrates containing some organic solvent designed for dilution prior to use. Thus in many instances, it is desirable to make up a concentrate having a relatively small quantity of solvent which may be diluted to use concentrations in the field. Such concentrates generally comprise between about 6% and about 50% solvent inclusive, the compositions preferably containing between about 8% and about 30%, inclusive. These percentages are based on the weight of the composition. When the concentrates are diluted in the field, the resulting compositions generally contain by weight from about 40% to about 90% solvent, inclusive, and preferably from about 60% to about 80%, inclusive, Both concentrates and use compositions are within the scope of the present invention.

The drawing shows the effect of the inorganic salt in a composition according to the invention. This is hereinafter more fully discussed.

A further discussion of the several ingredients follows;

2,901,433

THE SOAP

The term soap as used in the present invention includes both conventional soaps and the anionic detergents.

The function of soap in the present compositions is to exert· a detergent action on the soil to be attacked, to aid in dissolving the organic solvent in the water of the composition, and to serve as the base for solubilization of oils and greases.

The soap employed in the present compositions may be a “conventional” soap, that is, an alkali metal, ammonium, amine or alkanol amine salt of a fatty or rosin acid,, such, for example, as the alkali metal, ammonium, morpholine, isopropylamine, or ethanol amine salts of caproic, lauric, palmitic, stearic, oleic, linoleic, ricinoleic, or abietic acid.

If the soap is the salt of a fatty acid, the acid should preferably have more than 5 and less than 26 carbon atoms in the molecule.

Among the conventional” soaps, the soaps of oleic acid are generally preferred, such as potassium and sodium oleate. However, these compounds are relatively expensive, and use may be had of more economical soaps such as those made from tall oil.

Tall oil is a by-product of the paper industry, and contains principally rosin acids, oleic acid, and linoleic acid. It is readily saponified with caustic to give what will be referred to as tall oil soap. One suitable tall oil soap contains :

Grams

Crude tall oil --------. 650

NaOH -— 79

Water__----------1,280

The “conventional” soap may be added as such, or the acid may be added to the other ingredients and then neutralized in situ with the desired base.

The invention also uses synthetics of the anionic type generally referred to as anionic detergents. Examples of these are the sulfates and sulfonates derived from long chain alcohols such as sodium octyl sulfate, sodium decyl sulfate and sodium dodecyl sulfonate and alkyl aryl sulfonates having the general formula R—Ar—SO3M where M is alkali metal or ammonium, Ar is phenyl or naphthyl and R is an alkyl group, such for example, as sodium dodecyl benzene sulfonate.

CiJmbinations of different soaps may often be employed advantageously. Thus, mixtures of conventional soaps and anionics may be used.

Though nonionic detergents are not included among thb soaps found suitable for the compositions of the present invention, inclusion of these together with the soap used has been found to give excellent results. This is particularly true where the cleaning composition is to be used for application to a badly soiled area in small quantities followed by flushing with water, since the non-ionic promotes the rapid emulsification of the soilladen cleaner. When a non-ionic detergent is used it is generally included in the cleaning composition in amounts of about 0.5% to 5% by weight inclusive.

THE WEAK ORGANIC ACID

The weak organic acid employed should have an ionization constant not greater than that of benzoic acid (6.3X IO^-5). The acid may be a fatty acid, either saturated or unsaturated; an aliphatic acid other than a fatty acid, as for example, the acids derived from the oxidation of petroleum; an aromatic acid, as for example, benzoic acid or cinnamic acid; a cyclic acid, such as abietic acid; or a heterocyclic acid, such as picolinic acid.

Rosin acids such as abietic acid and fatty acids having from 6 to 26 carbon atoms such as caproic, lauric, palmitic, stearic, oleic, linoleic, and ricinoleic, are generally preferred. Of this group, oleic acid and tall oil, a mixture of rosin and fatty acids, are the acids of choice,, the latter particularly because of its low cost. Crude or refined tall oil may be used.

One function of the fatty acid is to promote the solubilizing power of the soap.

More important, however, the fatty acid cooperates with the inorganic salt, vastly to increase the solubiliz5 ing power of the composition, as will be brought out more fully below.

THE NEUTRAL SALT

The neutral salt in the present formulations functions 10 in cooperation with the weak organic acid greatly to increase the solubilizing power of the formulation. Where the composition includes an organic solvent, the salt also acts with the fatty acid to increase the capacity of the aqueous base system of the present invention for the 15 solvent.

Any neutral salt may be employed, providing that it is sufficiently soluble in the composition to reach the minimum prescribed salt content of 0.05% by weight. A few examples of such neutral salts are sodium sulfate, 20 potassium sulfate, sodium chloride, potassium chloride, and sodium chromate. Ferric chloride and ferrous sulfate were found satisfactory after their solutions were neutralized.

The effect of increasing the salt content on the mineral 25 oil solubility of a formulation prepared according to the invention, is shown by the following experiment, in which sodium sulfate was used as the neutral salt.

A number of portions of a basic mixture were prepared, each portion consisting of:

Grams

Crude tall oil soap22

Cyclohexanol 7

Refined tall oil 15

Water_____________________-—:38 ®5 To each of several samples of the basic mixture were added different quantities of sodium sulfate. Kerosene was then added to each sample in the amount required to clear the solution and this amount recorded. The curve of the drawing designated “Kerosene to Clear” ⁴⁰ shows the relationship between the amount of kerosene added and the grams sodium sulfate present in each sample of the basic mixture.

Mineral oil (SAE 30) was then added carefully, with stirring, to 100 cc. samples of each of the mixtures containing the basic mixture, sodium sulfate and kerosene ⁴⁵ and a record made of the maximum amount of oil that each sample would dissolve. The curve in the drawing, “Mineral Oil Solubilized” shows the relationship between the amount of SAE 30 mineral oil solubilized and the sodium sulfate and kerosene content of the system. It ⁵⁰ will be noted from this graph that the solubilizing power of the system went through a maximum where 100 cc. of a sample containing basic mixture, 1.5 grams sodium sulfate and approximately 380 cc. kerosene were used.

The most striking observation to be drawn from the ⁵⁵ figure, however, is the tremendous increase in the solubilizing ability of the system for the mineral oil obtained by adding the salt, compared to the formulation with no salt.

Thus, with no salt added, 12 cc. of medium viscosity θθ mineral oil were solubilized per 100 cc. of cleaner. With the addition of only 0.4 gram of salt the amount of mineral oil solubilized increased to approximately 40 cc. This is a surprising increase of over 300%.

It is quite surprising and entirely unexpected that the θ5 solvency of a predominantly organic liquid, quantitatively speaking, containing only about 12% water, for other organic substances should be so tremendously improved by a small amount of an inorganic salt.

Moreover, as noted above, the salt and the free fatty ⁷⁰ acid present in the novel formulations, have a synergistic action. This is illustrated in Table I (below).

Column A of Table I shows a formulation containing a neutral inorganic salt (1 gram Na₂SOi) and substan75 tially no free organic acid, since all the tall oil has been

2,901,433 neuttalized by the NaOH. With this formulation a homogeneous system could not be obtained with the addition of solvent, and only 2.5 cc. of mineral oil were solubilized per 100 cc. of composition.

Column B shows a composition including an excess of organic acid, but no salt. With this formulation a stable solution was obtained with 230 grams of solvent, but again only a very small amount (3.0 cc.) of mineral oil was solubilized.

In column C, a composition is shown containing both free organic acid and neutral salt according to the invention. This composition solubilized 23 cc. of mineral oil. It is thus clear that only when both weak organic acid and neutral salt are present, are the benefits of the invention achieved.

TABLE I

TaU Oil__________________________

Methylpentanediol (Hexylene glycof)__ NaOH..................................

Na₂SO4-___'___________— __ h₂o__________________________.....

Solvent_________________________________ cc. of SAE 30 Oil solubilized/ϊθό g. composition—........___________.________

<td> A (Gms.)</td><td> B (Gms.)</td>

<td> 22.5</td><td> 60.0</td>

<td> 20.0</td><td> 20.0</td>

<td> .3.0</td><td> 3.0</td>

<td> 1.0</td><td></td>

<td> 34</td><td rowspan="2"> 34 230 3.0</td>

<td> 2.5</td>

C (Gms.)

60.0

20.0

3.0

1.0

230

THE ALCOHOL

It is believed that the alcohol in the present composition generally acts to improve the solubilizing power of the soap.

The alcohols employed in the present formulations should be liquid at normal temperatures and soluble in the system. Alcohols at least sparingly soluble in water are preferred, and alcohols of between about 3 and about 10 carbon atoms are considered satisfactory. Some examples of suitable alcohols are isopropanol, butanol, pentanol, cyclohexanol, the monoethyl and monobutyl ethers of ethylene glycol, methyl pentane diol, and alpha terpineol. Combinations of alcohols may be used advantageously, as for example, a combination of cyclohexanol and butanol, or of alpha terpineol and isopropanol.

THE ORGANIC SOLVENT

The organic solvent used may be any organic liquid which will dissolve the grease which it is desired to attack. Usually, the organic solvent will be a hydrocarbon derived from petroleum or from coal tar. It may have either an aliphatic or an aromatic base, and usually has a boiling-point range between about 75° C. and about 400° C., preferably between about 110° C. and about 330° C.

Some examples of suitable hydrocarbon solvents are kerosene, gasoline, benzine, benzene, toluene, xylenes, and Stoddard solvent. For purposes of safety, it is desired in some applications, to use solvents having a high flash point, i.e., having a flash point over 100° F., such as Stoddard solvent.

Some other conventional solvents that may be used are carbon tetrachloride, perchloroethylene, trichloroethylene.

Where an alcohol is included, solutions made accord- 60 ing to the invention are clear and bright. So far as physical appearance and stability are concerned, they have all the characteristics of true solutions.

In those formulations which include fatty acid salts as the soaps, the preferred method of manufacture is to start 63 with a liquid composed of water, alcohol, and excess organic acid. An appropriate caustic e.g., NaOH, is then added slowly.

The dispersion will first become a cloudy viscous liquid, then a clear gel, and finally a clear fluid liquid 70 which foams slightly.

In all formulation, the addition of solvent is preferably handled in the same manner and similar changes are noted. That is to say, the solvent, e.g., kerosene is added gradually to a mixture of soap, water, alcohol, and acid. As the kerosene is added, a cloudy dispersion, then a clear gel, then a somewhat viscous clear liquid, then a cloudy dispersion, and finally a fluid clear liquid may be observed. For some uses it is sometimes pre6 ferred to discontinue addition of the kerosene or other solvent prior to obtaining the first fluid clear liquid.

The following examples are given to illustrate the invention. It will be understood, however, that these examples are merely illustrative and are not to be taken in 10 any way as limiting the invention as defined in the appended claims.

Example 1

Percent by weight

Refined tall oil___:________54.3

Hexylene glycol____________________ 11,8

Sodium hydroxide __ 2.7

Sodium sulfate ___________________________ 0.9

Water ___________________;________30.3

2q Example II

Percent by weight

Sodium oleate__,_____________ 5.1

Oleic acid___________________________.,______ 3.0

Butanol___:________._________________________ 3.0

2₅ Cyclohexanol ___________________________ 5.4

Kerosene_____________________44.1

Sodium tripolyphosphate_____________________ 0.6

Water —:--------------------38.8

Example III ³⁰ Percent by weight

Soap of tall oil (sodium tallate) 14.0

Tall oil_______ 14.2

Cyclohexanol 10.8

Kerosene33.8

Sodium sulfate _

Water27.2

Example IV

Percent by weight

Tall oil soap (prepared by reacting 650 parts by weight crude tall oil, 79 parts NaOH, and 1280 parts H₂O) 18.0

Cyclohexanol___: 2.5

Kerosene 72.6

Tall oil (refined) ,___; 5.4

Na₂SO₄ (added as 80 cc. of a solution containing 2 grams per 100 cc.) 1.5

Example V

Percent by weight

Cyclohexanol _____________________________3.2

Water_______________________.__________19.9

Kerosene__________________ 44 8

NaOH --------------------------------_____ 05

An alkyl aryl sulfonate (containing about 8% water) 20.8

Na₂SO₄ 1.2

Tall oil (crude) 9.6

Example VI Percent by weight

Refined tall oil 19.9

Hexylene glycol 17.7

NaOH 2.7

Benzoic acid __ 17.7

Na₂SO₄ 0.9

Hiflash petroleum hydrocarbon solvent (boiling range 520-625° F.)_____________________;11.0

Water______________________30.1

Example VII Percent by weight

Hiflash petroleum hydrocarbon solvent (boiling range 520-625° F.)_____________________ 74.94

Water _______________________________________ 7.62

Tall oil (refined) __________________________ 12.58

Hexylene glycol 3.89

NaOH (97 percent) 0.73

Na₂SO₄ 0.24

2,901,433:

Example VIII

Percent by weight

Kerosene _-----68.6

Water------1θ·2

Tail oil (refined)13.5

Hexylene glycol. 4.5

NaOH (97 percent) 0.7

Na₂SO₄------ 0-2

Brij: 30^; (a nonionic emulsifier consisting essentially of the polyoxyethylene, ether of lauryl alcohol)— 2.3

Example IX

Percent by weight

Kerosene' 70.67

Water - 10.19

Tall oil (refined) — 13.67

Hexylene glycol 3.22

NaOH (97 percent) 0.64

Na₂SO₄ —________——- °·

Pine oil ------------——. 1.37

Example X

Percent by weight.

Refined tall oil —-------—43.4

Hexylene glycol----------—---------14.7

NaOH — ___— ----———— 2.1

Na₂SO₄ ——----'-------—--------- .8

Nbnic 218 (tertiary dodecyl mercapto polyethylene glycol)___'------——---------------- 7.1

Water_______________________22.0

Petroleum solvent 9.9 (This may be used as such but is designed primarily as a. concentrate. It is preferably diluted prior to use with 3: volumes of a petroleum solvent or Vs volume of water and 3 volumes of a petroleum solvent.)

Compositions according to the invention will readily remove mineral and cottonseed oils from metal panels. They have also removed a particularly tenacious cup grease and have been found to be substantially superior to present commercially available cleaners for removing buffing compounds from zinc base die castings. In another application·, one of these cleaners removed partially carbonized heat-treating oils much more effectively than available commercial materials.