JP6332603B2 - Rust preventive composition - Google Patents

Description

The present invention relates to a rust preventive composition having a rust preventive effect particularly on aluminum or an alloy thereof.

Cited Document 1 describes that a rust inhibitor composition containing triazoles has a rust preventive effect on non-ferrous metals. However, it does not target aluminum or an aluminum alloy, and only performs a rust prevention test at room temperature.

In Cited Document 2, an addition salt of benzotriazole and a water-soluble amine, and an addition salt of t-butylbenzoic acid and a water-soluble amine are synthesized and added. It is described that the solubility is improved by using it as an addition salt. However, the reason why the solubility is required is that the invention of Patent Document 2 is directly added to the coolant, and if added to the coolant in a dissolved state, there is no need to make an addition salt. In addition, a phosphate buffer is used, which may cause recent environmental pollution.

JP-A-60-251287 JP 60-162785 A

Conventionally, anticorrosive effect is hard to be exhibited against aluminum and its alloys which are easily corroded, and particularly in a rust preventive composition which does not use a phosphate buffer, reliability such as a high temperature atmosphere left in an atmosphere of 90 ° C. In the test, corrosion easily proceeds and it was difficult to maintain the rust prevention effect.

As a result of intensive studies to achieve the above object, the present inventors have completed the present invention relating to a rust preventive composition.

The gist of the present invention will be described next. The first embodiment of the present invention is a rust preventive composition containing the components (A) to (C) and the component (C) containing the components (C-1) to (C-4).
(A) component: medium (B) component: buffer (C) component: rust inhibitor (C-1) component: a compound having a carboxylic acid and an amine in the molecule and / or a salt thereof (C-2) component : Compound having chemical structure of general formula 1 and / or its derivative (C-3) component: Compound having chemical structure of general formula 2 and / or its derivative (C-4) component: nitrate

The second embodiment of the present invention is the rust inhibitor composition according to the first embodiment, wherein the component (B) is a citrate buffer or a malate buffer.

The third embodiment of the present invention is the rust inhibitor composition according to the first or second embodiment used as a coolant additive.

A fourth embodiment of the present invention is the rust preventive composition according to the first or second embodiment used for an aluminum alloy radiator.

The present invention provides a rust preventive composition that exhibits a rust preventive effect on corrosive aluminum and its alloys, and maintains a rust preventive effect even in a high-temperature atmosphere such as 90 ° C. without using a phosphate buffer. It is a thing. The present invention can be added to a radiator coolant made of aluminum or an alloy thereof, and suppresses the generation of rust even after a reliability test.

Details of the present invention will be described below. The component (A) that can be used in the present invention is a medium in which each component is dissolved, and preferably a medium that makes the composition transparent and uniform. Particularly preferred is a medium having hydrophilicity, and one kind may be used alone, or two or more kinds may be mixed and used.

Specific examples of the component (A) include ion exchange water, ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, 1,3-propanediol, 1,3-butanediol, 1,5-pentanediol, hexylene glycol. However, it is not limited to these.

The component (B) that can be used in the present invention is a buffer. The buffering agent refers to a solution having a buffering action that prevents the pH from changing greatly even if a small amount of acid or base is added or the concentration slightly changes.

Specific examples of the buffer include a phosphate buffer, a citrate buffer, a malate buffer, and the like. In consideration of environmental pollution, a citrate buffer and a malate buffer are particularly preferable. Known examples of the citrate buffer include a solution in which citric acid monohydrate and trisodium citrate are mixed at a mass ratio of 1: 4. Malate buffer includes malic acid and disodium malate. A solution in which 1: 4 is mixed at a mass ratio is known, but is not limited thereto. The component (B) may be added to the component (A) in a state dissolved in the medium, or the component (B) may be added to the component (A) as it is.

It is preferable that 0.1-5.0 mass parts of (B) component is added with respect to 100 mass parts of (A) component. If it is 0.1 mass part or more, pH can be stabilized. On the other hand, if it is 5.0 mass parts or less, the cloudiness and sedimentation which generate | occur | produce in a rust preventive agent composition can be suppressed.

The component (C) that can be used in the present invention is a combination of specific rust preventives, and specifically, the combination of the following components (C-1) to (C-4). Moreover, rust preventives other than (C) component can also be added in the range which does not reduce the characteristic of a rust preventive composition.

The component (C-1) is a compound having a carboxylic acid and an amine in one molecule and / or a salt thereof. One type may be used alone, or two or more types may be mixed and used. Specific examples of the component (C-1) include glutamic acid, sodium glutamate, potassium glutamate, aspartic acid, sodium aspartate, potassium aspartate, 2,6-diaminohexanoic acid, sodium 2,6-diaminohexanoate, 2, Examples include, but are not limited to, potassium 6-diaminohexanoate, 2-amino-3-methylvaleric acid, sodium 2-amino-3-methylvalerate, potassium 2-amino-3-methylvalerate, etc. is not.

The component (C-2) is a compound having a chemical structure of the general formula 1 and / or a derivative thereof. One type may be used alone, or two or more types may be mixed and used. Specific examples of (C-2) include benzothiazole and 2-mercaptobenzothiazole, but are not limited thereto.

The component (C-3) is a compound having a chemical structure of the general formula 2 and / or a derivative thereof. Here, R in the general formula 2 represents hydrogen or an organic group. One type may be used alone, or two or more types may be mixed and used. Specific examples of the component (C-3) include, but are not limited to, benzotriazole, 1-hydroxybenzotriazole, 1H-naphtho [2,3-d] triazole, and 4-nitrobenzotriazole. is not.

The component (C-4) is nitrate. One type may be used alone, or two or more types may be mixed and used. Specific examples of the component (C-4) include sodium nitrate, magnesium nitrate, calcium nitrate, potassium nitrate, strontium nitrate, and aluminum nitrate, but are not limited thereto.

It is preferable that 0.1-20 mass parts of total of (C) component is added with respect to 100 mass parts of (A) component. If it is 0.1 mass part or more, a rust prevention effect will express. On the other hand, if it is 20 mass parts or less, the cloudiness and sedimentation which generate | occur | produce in a rust preventive agent composition can be suppressed. In addition, as a ratio of the components (C-1) to (C-4), (C-1) component: (C-2) component: (C-3) component: (C-4) component = 1: 0. It is preferable that it is 5-1.5: 0.05-0.3: 0.5-1.5.

The optimum pH of the rust preventive composition is preferably 7.00 to 8.00. If it is the said range, when leaving a rust preventive composition in a high temperature atmosphere, sedimentation and white turbidity do not generate | occur | produce.

The rust inhibitor composition of the present invention can be used as an additive for a coolant filled in a radiator or the like, and can prevent metal corrosion inside a pipe such as a radiator. In particular, it can be used for a radiator made of aluminum or aluminum alloy.

The rust preventive composition of the present invention includes pigments, dyes and other colorants, metal powders, calcium carbonate, talc, silica, alumina, aluminum hydroxide and other inorganic fillers within the range that does not impair the characteristics of the present invention. An appropriate amount of additives such as a flame retardant, an organic filler, a plasticizer, an antioxidant, an antifoaming agent, a leveling agent, and a rheology control agent may be blended. By adding these, a composition excellent in workability and storage stability and a cured product thereof can be obtained.

EXAMPLES Next, although an Example is given and this invention is demonstrated further in detail, this invention is not limited only to these Examples. (Hereinafter, the rust inhibitor composition is simply referred to as a composition.)

[References 1 to 17, Examples 1 and 2 and Comparative Examples 1 to 6]
The following ingredients were prepared to prepare the composition.
(A) component: Medium, ethylene glycol (manufactured by Gordo Co., Ltd.)
・ Ion exchange water (manufactured by Kyoei Pharmaceutical Co., Ltd.)
Component (B): Buffering agent / Buffering agent 1 (citric acid monohydrate: trisodium citrate = 1: 4 (mass ratio))
Buffer 2 (malic acid: disodium malate = 1: 4 (mass ratio))
Component (C): Rust preventive agent / Sodium glutamate (reagent)
・ Benzothiazole (reagent)
・ Benzotriazole (reagent)
・ Sodium nitrate (reagent)
Other rust preventives, sodium benzoate (reagent)
・ Sodium p-tert-butylbenzoate (reagent)
・ Maleic acid (reagent)
・ Adipic acid (reagent)
・ Heptanoic acid (reagent)
・ Stearic acid (reagent)
・ Salicylic acid (reagent)
・ Nonanoic acid (reagent)
・ Sodium glutamate (reagent)
・ Benzothiazole (reagent)
・ Benzotriazole (reagent)
Other ingredients, acetylene-based antifoaming agent (Olfin SPC, manufactured by Nissin Chemical Industry Co., Ltd.)

In order to adjust the references 1 to 17, the components (A) and (B) are weighed and stirred for 60 minutes to dissolve the component (B). Thereafter, the component (C) or other rust inhibitor and other components are weighed and then stirred for 60 minutes. Detailed preparation amounts follow Table 1, and all numerical values are expressed in parts by mass.

Corrosion tests were performed on References 1-17. In addition, the total score of each test was described as “overall evaluation”. The results are summarized in Table 2.

[Corrosion test]
Use the corrosive liquid described in JIS K2234 (1L ion-exchanged water, 148mg sodium sulfate, 165mg sodium chloride, 138mg sodium bicarbonate) and add 2% by mass of the composition to the corrosive liquid. To make an immersion liquid. Aluminum, stainless steel, iron, and copper were immersed in the immersion liquid as test pieces, respectively, and allowed to stand in an atmosphere at 25 ° C. for 300 hours in a sealed state so that the medium did not volatilize. Thereafter, the test piece is taken out and dried, and the corrosion of the test piece surface is visually confirmed according to the following evaluation criteria. The confirmation results of each metal are described as “aluminum”, “stainless steel”, “iron”, and “copper”.
Evaluation criteria ○ (2 points): No rust is observed on the surface of the test piece △ (1 point): Partial rust is seen on the surface of the test piece × (0 points): Rust is generated on the entire test piece Yes.

In References 1 to 11 using one kind of rust preventive agent, rust occurred on at least one kind of metal among the four kinds of metals. In Reference 12 using two types of rust preventives, rust was generated in iron among the four types of metals. In References 13 to 17 using three kinds of rust preventives, only Reference 17 combining sodium glutamate, benzothiazole and benzotriazole as rust preventives did not generate rust when left at 25 ° C.

In order to adjust Example 1 and 2 and Comparative Examples 1-6, (A) component, (B) component, (C) component or other rust preventive agent, after mixing other components, it stirs for 60 minutes. Detailed preparation amounts are in accordance with Table 3, and all numerical values are expressed in parts by mass.

For Examples 1 and 2 and Comparative Examples 1 to 6, a corrosion test after the 90 ° C. accelerated test and an appearance confirmation after the 90 ° C. accelerated test were performed. In addition, the total score of each test was described as “overall evaluation”. The results are summarized in Table 4.

[Corrosion test after 90 ° C accelerated test]
Use the corrosive liquid described in JIS K2234 (1L ion-exchanged water, 148mg sodium sulfate, 165mg sodium chloride, 138mg sodium bicarbonate) and add 2% by mass of the composition to the corrosive liquid. This is referred to as “immersion liquid”. In a 90 ° C atmosphere, aluminum, stainless steel, iron, and copper are immersed in the immersion liquid as test pieces, and aluminum, stainless steel, iron, and copper are immersed as test pieces in a sealed state so that the medium does not volatilize. And left for 300 hours. Thereafter, the test piece is taken out and dried, and the corrosion of the test piece surface is visually confirmed according to the following evaluation criteria. The confirmation results of each metal are described as “aluminum”, “stainless steel”, “iron”, and “copper”.
Evaluation criteria ○ (2 points): No rust is observed on the surface of the test piece △ (1 point): Partial rust is seen on the surface of the test piece × (0 points): Rust is generated on the entire test piece Have

[Appearance confirmation after 90 ° C accelerated test]
The immersion liquid in the corrosion test after the 90 ° C. accelerated test is visually checked for the presence or absence of precipitation or cloudiness, judged according to the following evaluation criteria, and the confirmation result is described as “appearance”.
Evaluation criteria ○ (2 points): There is no precipitation or cloudiness in the immersion liquid. × (0 points): There is precipitation or cloudiness in the immersion liquid.

In Comparative Example 1 in which sodium glutamate, benzothiazole, and benzotriazole were combined as the component (C), it was confirmed that there was a problem in appearance although rust did not occur in the metal when left in an atmosphere at 90 ° C. The cause of the occurrence of white turbidity and precipitation is not clear, but since it is presumed that the chemical has greatly changed, it cannot be said that the composition is in a good state. On the other hand, in Examples 1 and 2 in which sodium nitrate was further added to sodium glutamate, benzothiazole, and benzotriazole, rust did not cause white turbidity or precipitation, and the overall evaluation was the best. Even if component (B) was changed, Similar effects were manifested. In Comparative Examples 2 to 6 in which sodium nitrate was added as the component (C) and other rust preventives were changed, there was a problem in appearance and a tendency for rust to be generated in the metal was observed.

In recent years, aluminum or aluminum alloys are sometimes used from the viewpoint of weight reduction of vehicles. However, there is a problem that the metal is easily corroded, and it is important to suppress corrosion when used in a vehicle. If it is the rust preventive effect of this invention, it is a rust preventive composition which can be used not only for a coolant additive but for another use.

Claims (3)

A rust inhibitor composition comprising (A) to (C) components, wherein the (C) component comprises (C-1) to (C-4) components.
(A) component: medium (B) component: citrate buffer or malate buffer (C) component: rust inhibitor (C-1) component: sodium glutamate (C-2) component: Formula 1 below A compound having the chemical structure
(C-3) Component: Compound having the chemical structure of the following general formula 2
(In general formula 2, R represents hydrogen)
(C-4) Component: Sodium nitrate
The rust preventive composition according to claim 1, which is used as a coolant additive. The rust preventive composition according to claim 1 or 2, which is used for an aluminum alloy radiator.