SE448240B - STABILIZED SILICATE COMPOSITION CONSISTING OF A SOLUBLE SILICATE AND A SILYL ALKYL PHOSPHONATE - Google Patents

Description

448 240 or carbinol group and a silicate. These materials are said to be "remarkably soluble in aqueous liquids".

Furthermore, the compositions are claimed to eliminate many of the above-mentioned disadvantages.

Finally, U.S. Patent No. 3,948,964 issued April 6, 1976 discloses the stabilization of partially hydrolyzed silicic acid esters using stabilizers selected from organic compounds, such as cyclic esters, ether alcohols, carboxylic acid esters and ketones. Such stabilized materials are described as binders for zinc powder pigments and the like.

However, none of the above references discloses the composition of the present invention. The advantages of the prior art methods can be obtained with the present invention and further advantages over the prior art are obtained by this invention. Most noticeable are the benefits of low cost, improved efficiency in the stabilization of silicates and the resistance of corrosion inhibition.

It is characteristic of the invention that the silicate composition consists of a soluble silicate in the parts by weight 0.1 to 99.9 with the general unit formula (Mo) asio4_a 2 wherein M is a cation selected from a group consisting of sodium, potassium, lithium, rubidium and tetraorganoammonium cations and to which silicate is added with the parts by weight 99.9 to 0.1 a silylalkylphosphonate, having the general unit formula a has a value of 1-3, MO 1 MOROIROPHOM OR '1 wherein M is a cation selected from the group consisting of sodium, potassium, lithium, rubidium and tetraorganoammonium cations7 R is a divalent aliphatic hydrocarbon radical having 1 to 3 carbon atoms and R 'is a hydrocarbon radical or halogenated hydrocarbon radical having 1 to 7 carbon atoms. The phosphonate is obtained by silyl alkyl esters of phosphorus by reacting an alkali metal hydroxide with esters of phosphorus.

The precursor phosphorus compound, i.e. The silyl alkyl esters of phosphorus, can be prepared by several methods, but it is preferred to prepare them by the method shown in U.S. Patent No. 4,093,641 issued June 6, 1978 to Plueddemann. Plueddemann's method is simple to perform and gives high returns, which gives the resulting product a low cost. The precursor phosphorus compounds are then treated with dilute sodium hydroxide and refluxed for several hours to saponify the phosphonate precursor. The resulting product, in the case of using sodium hydroxide, is I O 1 NaO? IRO? OONa O R 1 i.e. the sodium salt of the sodium siliconatesilylalkylphosphonate.

In the actual practice and using a dichlorobenzyl dimethyl phosphate as an example, the preparation is as follows: cl cH2Po (ocH3) 2 + cl hensyldimethylamineš (cH3o) 3sicH2cH2c1-12c1 135-200 ° C / 6 hours O ll cl Q cH21 |> ocH2cH2s1 (ocH3) 3 Cl OCH3 (I) (I) + NaOH aqueous É- f reflux / several hours 10 15 20 25 30 35 4 240 4 I f? 9 Cl <:::;> CH2? OCH2CH2CH2siONa Cl 9 9 Na The resulting product was used alone or in conjunction with a silicate as will be explained below.

As mentioned earlier, the products are according to the invention, ie. the alkali silicone silicon alkyl alkyl phosphonates are capable of stabilizing silicates which are useful as corrosion inhibitors of metals. Thus, the obvious uses for such materials in antifreeze compositions, where metal corrosion is common due to high temperatures, which cause decomposition of the alcohols are typically used as freezers. If the silicates protect the internal metal parts of a cooling system, such as an automobile engine, and if the silicates can be made to have lasting properties in the aqueous system, then there is a considerable advantage.

According to the invention there is also provided a composition of matter which is an improved corrosion inhibiting alcohol composition consisting essentially of an alcohol and, as a corrosion inhibitor, a corrosion inhibiting amount of a composition consisting essentially of a combination of (A) an alkali silicone silicone alkylphosphonate having the general formula: In MOSiROPOOM ORL wherein M is independently an alkali metal cation selected from the group (II) consisting of sodium, potassium, lithium, rubidium and tetraorganoammonium cations; R is divalent aliphatic hydrocarbon radical containing 1-3 carbon atoms or benzyl radical; and R 'is a hydrocarbon radical or a halogenated hydrocarbon containing from 1 to 7 carbon atoms, with (B) a soluble silicate represented by the general unit formula: (III) (Mo) 2sio4_2 2 10 15 15 25 25 35 5 448 24o wherein M has the above meaning and a has a value of l ~ 3.

It is intended that the alcohol composition may be anhydrous or contain, in addition to the alcohol and phosphonate silicate, relatively small amounts of water and it is also intended that the alcohol composition may contain relatively large amounts of water, i.e. the alcohol compositions may be "concentrate" or "coolant".

The alcohols useful in the invention include both monomeric alcohols such as methanol, ethanol, propanol and butanol and polyhydric alcohols. such as ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, glycerol and mixtures of the above. What is meant are the common antifreeze alcohols, especially ethylene glycol.

The corrosion inhibitor in the above composition is a composition of material consisting essentially of (A) 0.1 to 99.9 parts by weight of an alka] silicone siliconalkyl phosphonate having the general unit formula: I 9 MOSiROïOOM 10 O R '| wherein M is independently an alkali metal cation selected from the group consisting of sodium, potassium, lithium, rubidium and tetraorganoammonium cations; R is a divalent aliphatic hydrocarbon radical containing 1-3 carbon atoms or the benzyl radical; and R 'is a hydrocarbon radical or halogenated hydrocarbon radical containing from 1 to 7 carbon atoms, having (B) 99.9 to 0.1 parts by weight of a soluble silicate represented by the general unit formula (MO) aSiO4_a 2 wherein M has the above meaning and 3 has a value of 1-3.

As stated above, essentially all ratios of phosphonate (A) to silicate (B) are effective to produce a metal corrosion inhibiting material. The ratio (A) to (B) depends on the particular system in which they are used.

Therefore, the most useful relationship in the invention between (A) and (B) is dependent on the amount of water in the system, the amount of alcohol and type present, the temperature of the aqueous medium and other additives or chemicals in the system.

The phosphonates have been discussed above and when thinking of component (B) of the invention it should be noted that the silicates intended therein are the water-soluble silicates and they are represented by the formula III shown above. M in this formula has the same meaning as stated above for M and is a cation which would make the silicate water soluble. Illustrative of alkali metal metasilicates, alkali metal tetrasilicates, alkali metal disilicates These are alkali metal orthosilicates, likates and tetraorganomammonium silicates.

Specific examples of these silicates are potassium metasilicate, lithium metasilicate, sodium orthosilicate, potassium disilicate, lithium orthosilicate, lithium disilicate, rubidium disilicate, rubidium tetrasilicate, mixed silicates (eg Na 2 O. Li 2 O 2 K 2 O 2 SiO 2), K ammonium silicate, phenyltrimethylammonium silicate, benzyltrimethylammonium silicate, guanidine silicate and tetra (hydroxyethyl) ammonium silicate. The preferred silicates are sodium and potassium silicates, especially sodium disilicate and potassium disilicate.

The silicate used in the preparation of the phosphonate-silicate inhibitor may be added to the reaction mixture as such or it may be formed in situ by adding the appropriate alkali hydroxide and silica to the reaction mixture.

It is within the scope of the invention that the combination of (A) and (B) may be mixtures of (A) and (B) or partial reaction products of (A) and (B) or mixtures of mixtures of (A) and ( B) and partial reaction products of (A) and (B).

The phosphonate-silicate combination can be prepared by simply mixing components (A) and (B) in the correct proportions and stirring to homogenize them.

The phosphonate-silicate combination is then added to the alcohol composition. The order in which phosphonate, silicate and alcohol are added is not critical as long as the materials are mixed well.

The alcoholic phosphonate-silicate combinations have been found to be useful in other areas besides automobile cooling. 10 15 20 25 30 35 448 240 So e.g. The materials can be used in cooling and air conditioning units, cooling coils, heat exchangers and the like.

It was previously stated that the phosphonate could be useful in this invention without in fact combining it with a silicate before use, i.e. the phosphonate could be added to aqueous systems without the silicate. According to the invention, therefore, the use of the phosphonate and phosphonate-silicate compositions in aqueous systems other than anti-freeze systems, i.e. non-alcoholic aqueous systems which come into contact with metal surfaces, ie such uses as scale control in geothermal power plants, scale control in conventional heat exchanger systems and the like.

The degree of combination (A) and (B) required to protect metals from corrosion depends on the metals to be protected, the system in which the combination was used, the temperature of the system and other components and additives used in the system. In general, the combination (A) and (B) is used in an amount as small as 20 parts per million up to 2 parts per 100 parts based on the weight of the aqueous liquid used.

For automotive engine coolants, it has been found that 200 parts of the phosphonate silicate, based on one million parts of the aqueous alcohol coolant, are effective in preventing corrosion. In non-alcoholic aqueous media, larger quantities are sometimes required. The preferred range, which is used for all systems within the scope of the invention, is 200 parts per million parts of aqueous medium to 2 parts per 100 of aqueous medium.

It is within the scope of the invention to add 0. such as anti-various additives, which give special properties, foaming agents, both organic and based on siloxane, dyes, the pH indicator, other inhibitors, thickeners and the like.

The following examples are shown to illustrate the invention and are not intended to limit its scope. 10 15 20 25 30 35 448 240 Example 1.

As stated above, according to the prior art, the materials are exposed to very unfavorable conditions, which affect their stabilizing properties. The materials of the invention were therefore subjected to adverse conditions in the following manner: Nyacol, a commercial silica sol, manufactured by Nyanza, Inc., Ashland, MA 01721, USA, was used in this example. The sol, which had a pH of 10.5 and which was Na + stabilized, contained about 15% silica, which had a particle size of about 2 mpm. The pH was reduced using 10% aqueous HCl solution as shown in Table I.

The freeze-thaw cycle consisted of placing 28 ml glass test tubes in the solutions in a freezer and freezing for 12 hours.

The test tubes were then removed from the freezer and allowed to thaw.

The solutions were then checked for the occurrence of precipitation indicating that the solution was not stable. EXAMPLE - To demonstrate the usefulness of the materials, a second colloidal silica was treated and subjected to similar adverse conditions. See Table II. The silicate was Ludox, manufactured by E.I. of Pont de Nemours and Co., Wilmington, Delaware, USA. The sun contains 30% silica and is ammonia stabilized. The pH of the sol was 9.4 and it had an average particle size of 13-14 mpm. The pH was reduced by adding 10% aqueous HCl solution as shown in Table II.

Example 3.

This example illustrates the stabilizing effect of the material in Nalcoag 1034A manufactured by Nalco Chemical Co., Chicago, Ill. 60601, USA. The sun is H + -stabilized and contains 34% silica. It has an acidic pH of 3.1 and the average particle size is 16-22 mpm.

The nalcoagen was made less acidic by the addition of ammonia before testing was done as shown in Table III. wl- 10 15 20 25 30 35 448 240 Example_§.

This example illustrates the stabilizing effects of mate- sm 30 manufactured by E.I. of Pont de Nemours and Co., Wilmington, Delaware, USA. The sol is Na + -rial in Ludox stabilized, has a pH of 9-10 and an average particle size of 7-8 mpm. The solutions were tested as shown in Table IV after being reduced in pH by the addition of 10% aqueous HCl.

Example_§.

This example illustrates the effect of pH on stability.

The stability of silicate / siliconate mixtures generally has a minimum at pH 8.

A 7.5: 1 molar ratio of sodium silicate "G" to the silicate "G" was sodium silicate manufactured by Philadelphia Quartz Co. and has a weight ratio of SiO 2 / Na 2 O of 3.22 and a pH of 10.8. The one-product product was used. according to the invention was a 1 molar aqueous siliconate, i.e. in? Ol'5SiCH2CH2CH2Oï-ONa.

CH3 The mixture, after aging for 1 day at room temperature, was acidified with 10% aqueous HCl to different pH and observed for gel time. on gel time 4> l week 6> l week 7> l week 8 l 3/4 hours 9 9 hours 10> l week The test at pH 4 showed no gelation at 1 year.

Example 6.

This example illustrates the effect of aging. A similar mixture, prepared in Example 5 above, was used for this example except that the 1 molar solution was the 5: 1 ratio of the silicate in the product. 10 15 20 25 30 35 448 240 10 Test Aging Stability Stability at room temp. at pH 8 A 10 sec. 30 sec.

B l min. 70 sec.

C 5 min. 20 min.

D 15 min. > l week E 45 min. > 1 week Samples D and E were still stable at the time of writing, approximately four weeks from their preparation.

Example Z This example shows the effect of sodium metasilicate, a low molecular weight silicate. A two molar sodium metasilicate solution was mixed with a two molar product, i.e.

U Ol'5SiCH2CH2CH2OFONa CH3 in a molar ratio of 7: 3. After aging at room temperature for 6 months, the equilibrium mixture was diluted with sodium metasilicate as indicated and then the pH was adjusted to 8 with a 10% aqueous HCl solution and the solutions were then observed for stability. molar ratio sodium metasilicate / phosphonate líå iii Éil Stability at pH 8> 1 week> 1 week 16 min.

Therefore, it can be observed that a mixture of sodium I metasilicate and a phosphonate according to the invention at a ratio of 4: 1 gives stable corrosion inhibitors which will not gel when neutralized. A fresh mixture at a 4: 1 ratio gelled for 6 minutes at pH 8, indicating that a period of equilibrium is beneficial.

Example 8 - Stabilization of a potassium silicate (Kasil 6).

A 1 molar potassium silicate solution with a weight ratio of SiO 2 / K 2 O of 2.10 (molar ratio 3.3: 1) made by Philadelphia Quarts, mixed with two proportions of 1 molar siliconate solutions and after aging for 15 minutes, the pH was adjusted to 8 by water content. % H01.

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Claims (1)

443 240 '16 PATENT REQUIREMENTS Stabilized silicate composition, characterized in that it consists of a soluble silicate in parts by weight 0.1 to 99.9 with the general unit formula (Mo) asio4_a 2 wherein M is a cation selected from a group consisting of sodium, potassium, lithium, rubidium and tetraorganomammonium cations and a has a value of 1-3, to which silicate is added with the parts by weight 99.9 to 0.1 a silylalkylphosphonate, with the general unit formula etc. MosiRolPooM lo R ' Wherein M is a cation selected from the group consisting of sodium, potassium, lithium, rubidium and tetraorganomammonium cations; R is a divalent aliphatic hydrocarbon radical having 1 to 3 carbon atoms and R 'is a hydrocarbon radical or halogenated hydrocarbon radical having 1 to 7 carbon atoms.