GB2131444A

GB2131444A - Aqueous emulsion type rust inhibitor

Info

Publication number: GB2131444A
Application number: GB08315890A
Authority: GB
Inventors: Hiroshi Ueno; Kazuo Nakano
Original assignee: Dai Ichi Kogyo Seiyaku Co Ltd
Current assignee: DKS Co Ltd
Priority date: 1982-06-22
Filing date: 1983-06-09
Publication date: 1984-06-20
Also published as: JPS58224179A; GB8315890D0; CA1200969A; GB2131444B; JPS6114230B2

Abstract

An aqueous emulsion rust inhibitor having an excellent rust inhibiting effect and capable of providing a hard, nonsticky coating, comprising (a) a salt of a higher aliphatic carboxylic acid with a heterocyclic compound selected from morpholine, its derivatives, pyridine and its derivatives, (b) an oil-soluble anti-rust agent selected from an alkaline earth metal salt of a higher aliphatic carboxylic acid, aromatic and aliphatic sulfonic acids, alkali metal and alkaline earth metal salts of aromatic and aliphatic sulfonic acids, an oxidized paraffin, and alkali metal and alkaline earth metal salts of oxidized paraffin, and (c) an inorganic pigment.

Description

SPECIFICATION Aqueous emulsion type rust inhibitor The present invention relates to a rust inhibitor, and more particularly to an aqueous emulsion type rust inhibiting composition having an excellent rust inhibiting effect and easy to handle.

In general, a metal is liable to corrode or rust by contact with water, air or a corrosive material, and accordingly various metal corrosion inhibitors or rust inhibitors have hitherto been employed.

These inhibitors are classified broadly into water-based rust inhibitors and oil-based rust inhibitors. In case of the water-based rust inhibitors containing an inorganic anti-rust agent as a main component, environmental pollution and safety owing to elements included therein have been called in question, and in case of the water-based rust inhibitors containing an organic anti-rust agent as a main component, no inhibitors having a satisfactory rust inhibiting effect have been obtained. For such reasons, oil-based rust inhibitors which are relatively superior in rust inhibiting effect, have been mainly employed. However, the oil-based rust inhibitors also have problems in inflammability, working environment and environmental pollution.Accordingly, development of a water-based rust inhibitor of a commercial value having an excellent rust inhibiting effect has been strongly desired.

The present inventors proposed an aqueous emulsion rust inhibitor of a good quality which had no defects of conventional rust inhibitors as mentioned above and had a rust inhibiting ability comparable to that of conventional oil-based rust inhibitors, and moreover, did not generate a stain even if the surfaces coated with the inhibitors were stacked in the state of insufficient drying or under a damp atmosphere, as disclosed in Japanese Unexamined Patent Publication (Tokkyo Kokai) No.

133472/1981. This rust inhibitor is an aqueous emulsion containing in water (a) at least one salt of a higher aliphatic carboxylic acid with a heterocyclic compound selected from the group consisting of morpholine, a morpholine derivative, pyridine and a pyridine derivative and (b) at least one compound selected from the group consisting of an alkaline earth metal salt of a higher aliphatic carboxylic acid, an aromatic or aliphatic sulfonic acid, an alkali metal salt of an aromatic or aliphatic sulfonic acid, an alkaline earth metal salt of an aromatic or aliphatic sulfonic acid, an oxidized paraffin, an alkali metal salt of an oxidized paraffin and an alkaline earth metal salt of an oxidized paraffin.

The compounds in the above component (b) are well known as effective components of oil-based rust inhibitors, but are water-insoluble. Therefore, in case of employing them in an aqueous system, it is necessary to emulsify or solubilize them in water by employing surface active agents. Surface active agents used for this purpose are required usually to have a HLB (hydrophilic-lipophilic balance) of not less than about 9.However, a practical water-based rust inhibitor cannot be obtained by the use of a general surface active agent such as aliphatic polyglycol ester, aliphatic alkanolamide, polyoxyethylene fatty acid ester, polyoxyethylene alkyl ether, polyoxyethylene sorbitan fatty acid ester, fatty acid alkali metal salt or higher fatty acid alkanol amine salt, since the above anti-rust agents (b) are emulsified or solubilized in water, but the rust inhibiting ability thereof is remarkably decreased. Also, in general, the higher fatty acid amine salt is hard to provide a stable system, since the emulsifying ability for the antirust agents (b) is poor.

The above-mentioned rust inhibitor proposed by the present inventors has the feature that by employing such an anti-rust agent (b) in combination with the component (a) which does not show a remarkable rust inhibiting ability in itself, a stable aqueous emulsion is formed and moreover the rust inhibiting ability is increased, thus the rust inhibiting ability is superior to that of conventional rust inhibitors. However, this rust inhibitor has the disadvantage that since the coating thereof is soft and stickly, it is hard to handle. Accordingly, a further improvement is required.

It is an object of the present invention to improve the above-mentioned aqueous emulsion rust inhibitor containing the components (a) and (b).

A further object of the invention is to provide an aqueous rust inhibitor which has an excellent rust inhibiting effect and moreover does not cause problems such as environmental pollution and inflammability and the coatings of which are hard and nonsticky.

These and other objects of the present invention will become apparent from the description hereinafter.

It has now been found that physical properties of the above-mentioned aqueous emulsion rust inhibitor containing the specific higher aliphatic carboxylic acid salt (a) and the specific water-insoluble anti-rust agent (b) can be remarkably improved by addition of a small amount of an inorganic pigment or filler, while the rust inhibiting ability is effectively maintained.

In accordance with the present invention, there is provided an aqueous emulsion rust inhibitor containing in water: (a) a salt of a higher aliphatic carboxylic acid with a heterocyclic compound selected from the group consisting of morpholine, a morpholine derivative, pyridine and a pyridine derivative, (b) a compound selected from the group consisting of an alkaline earth metal salt of a higher aliphatic carboxylic acid, an aromatic or aliphatic sulfonic acid, an alkali metal salt of an aromatic or aliphatic sulfonic acid, an alkaline earth metal salt of an aromatic or aliphatic sulfonic acid, an oxidized paraffin, an alkali metal salt of an oxidized paraffin and an alkaline earth metal salt of an oxidized paraffin, and (c) an inorganic pigment.

Although the proportions of the components (a), (b) and (c) are not particularly limited, preferably the ratio of the component (a) to the component (b) is from 5:95 to 80:20 by weight. Also, the amount of the component (c) is preferably from 0.1 to 20% by weight, especially 0.5 to 5.0% by weight, of the total weight of the components (a), (b) and (c). The solid content of the aqueous emulsion rust inhibitor of the invention is usually from 1 to 40% by weight.

One or more kinds of salts of higher aliphatic carboxylic acids with heterocyclic compounds are employed as a component (a) in the present invention.

The higher aliphatic carboxylic acids used for forming the component (a) are for instance those having 6 to 22 carbon atoms. They include, for instance, saturated and unsaturated monocarboxylic acids, saturated and unsaturated polycarboxyiic acids, fatty acids derived from natural fats and oils which are mixtures of carboxylic acids, and polymeric products of unsaturated carboxylic acids. Typical examples of the saturated monocarboxylic acids are, for instance, pelargonic acid, capric acid, undecylic acid, lauric acid, tridecylic acid, myristic acid, pentadecylic acid, palmitic acid, heptadecylic acid, stearic acid, nonadecanoic acid, arachic acid, and the like. Typical examples of the unsaturated monocarboxylic acids are, for instance, undecylenic acid, oleic acid, elaidic acid, cetoleic acid, and the like.Typical examples of the saturated polycarboxylic acids are, for instance, adipic acid, suberic acid, azelaic acid, sebacic acid, and the like. Typical examples of the unsaturated polycarboxylic acids are, for instance, linolic acid, linoelaidic acid, eleostearic acid, linolenic acid, parinaric acid, arachidonic acid, and the like. Typical examples of the fatty acids derived from natural fats and oils are, for instance, linseed oil fatty acid, olive oil fatty acid, cacao butter fatty acid, sesame oil fatty acid, rice bran oil fatty acid, soybean oil fatty acid, rapeseed oil fatty acid, palm oil fatty acid, castor oil fatty acid, peanut oil fatty acid, beef tallow fatty acid, mutton tallow fatty acid, sardine oil fatty acid, hardened sardine oil fatty acid, fin whale oil fatty acid, sperm whale oil fatty acid, hardened herring oil fatty acid, and the like.Typical examples of the polymeric products of unsaturated carboxylic acids are, for instance, dimer acid, maleinized oleic acid, maleinized castor oil fatty acid, maleinized dimer acid, maleinized product of rosin oleic acid, maleinized product of rosin castor oil fatty acid, and the like. Saturated carboxylic acids having 12 to 18 carbon atoms are preferably employed.

As heterocyclic compounds constituting the component (a), there are preferably employed morpholine, morpholine derivatives, pyridine and pyridine derivatives. Preferable morpholine derivatives are N-alkylmorpholines such as N-methylmorpholine and N-ethylmorpholine. Preferable pyridine derivatives are N-alkylpyridines such as 2-methylpyridine and 2-ethylpyridine.

An alkaline earth metal salt of a higher aliphatic carboxylic acid, aromatic and aliphatic sulfonic acids, alkali metal and alkaline earth metal salts of aromatic and aliphatic sulfonic acids, an oxidized paraffin, and alkali metal and alkaline earth metal salts of oxidized paraffin are employed as a component (b) of the rust inhibitor of the present invention. These compounds may be employed alone or in admixture thereof.

As alkaline earth metal salts of higher aliphatic carboxylic acids in the component (b), there are effectively employed calcium, barium and magnesium salts of the higher aliphatic carboxylic acids as exemplified above.

The sulfonic acids used as a component (b) include, for instance, an oil-soluble aromatic petroleum sulfonic acid, an alkylsulfonic acid, an arylsulfonic acid, an alkylarylsulfonic acid, and the like.

Typical examples of the sulfonic acids are dodecylbenzenesulfonic acid, dilaurylcetylbenzenesulfonic acid, paraffin wax-substituted benzenesulfonic acid, polyisobutylene-substituted benzenesulfonic acid, polyolefin-substituted benzenesulfonic acid, naphthalenesulfonic acid, alkylnaphthalenesulfonic acids, and the like.

The use of the alkaline earth metal salts of the sulfonic acids such as the magnesium, calcium and barium salts as a component (b) are particularly preferable.

The rust inhibiting effect can be remarkably raised by employing, as a component (b), the alkaline earth metal salt of the higher aliphatic carboxylic acid in combination with a compound selected from the alkali metal salt of the sulfonic acid, the alkaline earth metal salt of the sulfonic acid, the alkali metal salt of the oxidized paraffin and the alkaline earth metal salt of the oxidized paraffin. It is desirable that the ratio of the former carboxylate to the latter compound is from 20:80 to 80:20 by weight. When such a combination is employed as a component (b), there is obtained a very excellent result such that the rate of rust generation is O to 5% in a salt spray test (according to JIS K 2246 and JIS Z 2371) for 500 hours with a mild steel test specimen (SPCC-D steel sheet) coated with the rust inhibitor in thickness of 20 to 50 ym. On the other hand, when the component (a) is employed alone in the above-mentioned salt spray test (thickness of coating: 20 to 50 Hm) as a control, a rate of rust generation of 10 to 50% is observed after 24 hours.

Any of natural pigments, synthetic pigments and other metal powders can be employed as an inorganic pigment (c), and the use of those causing no problem in environmental pollution and safety is desirable. The synthetic pigments include, for instance, sulfides, sulfates, oxides, hydroxides, silicates, carbonates, carbon, and the like. The aqueous emulsion rust inhibitor is in general weakly basic and, therefore, alkali resistant inorganic pigments are preferred. Typical examples of the pigments used in the present invention are a natural pigment such as clay, ochre or barite, carbon black, titanium oxide, red iron oxide, whiting, silica, ultramarine, zinc white, black iron oxide, and the like.

The rust inhibitor of the present invention is of very practical use, since the coating becomes hard and the stickiness disappears by incorporation of a small amount of an inorganic pigment. Also, the rust inhibiting ability is scarcely affected by incorporation of several % of an inorganic pigment, and is very good.

Further, the rust inhibitor of the present invention has the advantage that desired hiding effect, gloss or delustering effect can be imparted to the coating of the rust inhibitor by suitably selecting the inorganic pigment to be used, and simultaneously an aesthetic impression can be imparted by coloration.

The dispersibility of the inorganic pigment in the rust inhibitor of the present invention is very good. The viscosity of the rust inhibitor can be freely adjusted by changing the solid content of the rust inhibitor or the proportions of the components, whereby it is also possible to further increase the dispersion stability of the inorganic pigment.

A process for preparing the rust inhibitor of the present invention is not limited to a particular one.

General processes are illustrated below.

(1) The components (a) and (b) are melt-blended, and to the molten mass is gradually added water, preferably hot water, with agitation to form an emulsion. To the emulsion is then added an inorganic pigment in the form of a powder or liquid, and the emulsion is agitated at ordinary temperature or an elevated temperature.

(2) A heterocyclic compound for constituting the component (a) is dissolved or dispersed in water, preferably hot water. The component (b) and a higher aliphatic carboxyic acid for constituting the component (a) are melt-blended, and to the molten mass is gradually added the solution or dispersion of the heterocyclic compound with agitation to form an emulsion. To the emulsion is added an inorganic pigment in the form of a powder or liquid, and the emulsion is agitated at ordinary temperature or an elevated temperature.

(3) An aqueous solution or dispersion of a heterocyclic compound for constituting the component (a) dissolved or dispersed in water, preferably hot water, is gradually added with agitation to a molten dispersion of the component (b), a higher aliphatic carboxylic acid for constituting the component (a) and an inorganic pigment.

In case of employing an alkaline earth metal salt of a higher aliphatic carboxylic acid as a component (b), it may be formed by, after forming an emulsion containing the higher aliphatic carboxylic acid, adding to the emulsion an alkaline earth metal hydroxide or oxide in the form of a powder or a dispersion in water or an alcohol.

A high melting point wax or an aqueous emulsion of a resin may be added to the rust inhibitor of the present invention for the purpose of improving the rust inhibiting ability or making the coating of the rust inhibitor of the present invention hard. The high melting wax or aqueous resinous emulsion is usually employed in an amount of 60 to 200% by weight of the rust inhibitor of the present invention on the basis of solids. As a high melting wax, there are employed natural and synthetic waxes having a melting point of not less than about 600C such as Japan wax, carnauba wax, candelilla wax, bees wax, shellac wax, solid paraffin, rice bran wax, microcrystalline wax, oxidized wax and oxidized ethylene wax.Examples of the aqueous emulsion of a resin are, for instance, an acrylic emulsion, a urethane emulsion, a polyVinyl acetate emulsion, a glyoxal emulsion, an alkyd resin emulsion, and the like.

In case of employing such a high melting wax, the wax is molten with the component (b) and thereafter the rust inhibitor emulsion of the invention is prepared in a manner as mentioned before. In case of employing the resinous emulsion, it is desirable that after forming the rust inhibitor emulsion in a manner as mentioned before, the resinous emulsion is added to the rust inhibitor emulsion.

In order to alter the flowability and the viscosity, to the rust inhibitor of the present invention may be added a mineral oil such as kerosene or mineral turpentine, a cellosolve solvent such as butyl cellosolve or ethyl cellosolve and an alcohol solvent such as methanol, ethanol or isopropanol. Also, other additives may be added to the rust inhibitor of the present invention, as occasion demands.

The present invention is more specifically described and explained by means of the following Examples, in which all % and parts are by weight unless otherwise noted. It is to be understood that the present invention is not limited to the Examples, and various changes and modifications may be made in the invention without departing from the spirit and scope thereof.

Example 1 A morpholine soap was prepared by melt-blending 6.4 parts of a fatty acid (molecular weight: 275) derived from hardened beef tallow and 2.4 parts (1.2 equivalents to the fatty acid) of morpholine.

To this soap was added 9.2 parts of a fatty acid (molecular weight: 41 5) derived from sheep wool, and they were uniformly melt-blended. To the molten mass was gradually added 81.2 parts of hot water of 80" to 900C with agitation to form an emulsion. After thoroughly agitating the emulsion, 0.8 part of calcium hydroxide powder was added to the emulsion, and it was then agitated for 1 hour at a temperature of 80" to 850C to give a viscous emulsion (rust inhibitor A). To this emulsion was added 5 parts of titanium oxide (commercial name "Tipaque" made by Ishihara Sangyo Kaisha, Ltd.), and the emulsion was agitated at 500C for 1 hour to give a viscous stable emulsion type rust inhibitor I.

Example 2 There were melt-blended 11 .2 parts of a fatty acid (molecular weight: 370) derived from sheep wool and 6.8 parts of calcium petroleum sulfonate (commercial name "CA-SON" made by Chuo Kasei Kabushiki Kaisha). On the other hand, 4.2 parts (1.2 equivalents to the sheep wool fatty acid) of Nethylmorpholine was dissolved in 77.3 parts of water heated at a temperature of 70" to 800C. The aqueous solution was gradually added to the above molten mass with agitation, and it was then agitated at a temperature of 700 to 800C for 30 minutes to give an emulsion. To the emulsion was added 0.5 part of calcium hydroxide, and it was agitated at a temperature of 800 to 850C for 2 hours to give a viscous emulsion (rust inhibitor B).To this emulsion was added 5 parts of carbon black (commercial name "Fuji 8P Black" made by Fuji Shikiso Kabushiki Kaisha), and the emulsion was agitated at 400C for 2 hours to give a viscous stable emulsion type rust inhibitor II.

Example 3 There were uniformly melt-blended by a high speed mixer 7.4 parts of a fatty acid derived from hardened beef tallow, 3.8 parts of calcium petroleum sulfonate (commercial name "Bryton" made by Witco Chemicals Co.), 4.5 parts of microcrystalline wax (commercial name "Hi-Mic-1 070" made by Nippon Seiro Kabushiki Kaisha) and 4.5 parts of a complex compound type anti-rust agent (commercial name "SAC 1700" made by Witco Chemicals Co.). On the other hand, 2.4 parts (1.0 equivalent to the hardened beef tallow fatty acid) of morpholine was dissolved in 70.8 parts of water heated at 900C, This solution was gradually added to the above molten mass with agitation to give an emulsion.After agitating the emulsion at a temperature of 750 to 800C for 30 minutes, a solution of 1.6 parts of Ba(OH)2 - 8H20 dissolved in 5 parts of hot water of more than 800C was added to the emulsion, and the emulsion was then agitated at a temperature of 800 to 900C for 2 hours to give an emulsion (rust inhibitor C). To this emulsion was added 3 parts of whiting (commercial name "A-Gohun" made by Maruya Calcium Kabushiki Kaisha), and the emulsion was agitated at 400C for 1 hour to give a viscous stable emulsion type rust inhibitor Ill.

Each of the rust inhibitors I, II and Ill obtained in the above Examples according to the present invention and the rust inhibitors A, B and C containing no inorganic pigment was sprayed to mild steel test specimens (kind: SPCC-D, size: 70x 1 50x0.8 mm) by an air spray gun. After drying the coatings, the thickness of the coatings was measured, and subsequently the coated test specimens were subjected to the salt spray test (concentration of salt: 5%, temperature: 350+1 OC, spray pressure: 1.0 kg/cm2) according to JIS K 2246 and JIS Z 2371 by employing a CASS testing machine (made by Suga Shikenki Kabushiki Kaisha). The rate of rust generation was determined by measuring the area of rust generation after degreasing. Simultaneously the appearance of the coatings was observed.

The results are shown in Table 1.

Table 1 Rust Thickness of Salt spray Rate of rust inhibitor coating (ymJ time (hour) generation (%) Appearance of coating 27.3 72 14 Flat white coating having 50.5 72 10 little stickiness II 35.7 504 < 5 Glossy black coating having 52.5 504 0 little stickiness Ill 30.5 504 < 5 Flat white coating having 55.5 504 0 little stickiness A 29.2 72 10.8 Yellowish transparent coating 47.0 72 5 having a large stickiness B 29.4 504 < 5 Yellowish transparent coating 46.9 504 0 having a large stickiness C 20.6 504 < 5 Yellowish transparent coating 50.1 504 0 having a stickiness As shown in Table 1 , the rust inhibitors I to Ill of the present invention have an excellent rust inhibiting ability which is approximately equal to that of the rust inhibitors A to C containing no inorganic pigment, and moreover they provide coatings having no stickiness on the surface and an excellent hiding property. Thus, the rust inhibitors of the present invention are of great practical use.

In addition to the ingredients used in the Examples, other ingredients can be used in the Examples as set forth in the specification to obtain substantially the same results.

Claims

1. An aqueous emulsion rust inhibitor containing in water: (a) a salt of a higher aliphatic carboxylic acid with a heterocyclic compound selected from the group consisting of morpholine, a morpholine derivative, pyridine and a pyridine derivative, (b) a compound selected from the group consisting of an alkaline earth metal salt of a higher aliphatic carboxylic acid, an aromatic or aliphatic sulfonic acid, an alkali metal salt of an aromatic or aliphatic sulfonic acid, an alkaline earth metal salt of an aromatic cr aliphatic sulfonic acid, an oxidized paraffin, an alkali metal salt of an oxidized paraffin and an alkaline earth metal salt of an oxidized paraffin, and (c) an inorganic pigment.

2. The aqueous emulsion rust inhibitor of Clairn 1, wherein the inorganic pigment (c) is present in an amount of 0.1 to 20% by weight of the total weight of the components (a), (b) and (c).

3. An aqueous emulsion rust inhibitor containing water and substantially as described with reference to any one of the Examples disclosed herein.