JP2002371270A - Antifreeze - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an antifreeze capable of exhibiting an effect of preventing or inhibiting metal corrosion in a cooling water system in an internal combustion engine (engine) even when a diluent water containing many corrosive ions is used as a diluent water for adjusting the concentration of the antifreeze or the antifreeze is diluted to 30 vol.% or lower. SOLUTION: The antifreeze comprises a glycol as the main component, and an aromatic monobasic acid, a molybdate, a tungstate, an aliphatic dibasic acid, an aliphatic monobasic acid, a phosphoric acid, a triazole, a thiazole and a phosphonic acid.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a JIS K
2234 (antifreeze), the cooling water for cooling an internal combustion engine (engine) such as an automobile is prevented from freezing, and at the same time, the cooling water is used for the purpose of preventing or suppressing metal corrosion of a cooling water system inside the internal combustion engine. The present invention relates to antifreeze used by mixing with antifreeze.

[0002]

2. Description of the Related Art In order to prevent or suppress the freezing of cooling water, this type of antifreeze mainly contains glycols having a freezing point depressing action, and contains a metal of a cooling water system in an internal combustion engine (engine). In order to prevent or suppress corrosion, various metal corrosion inhibitors are added.

At the time of use, the antifreeze solution is diluted with a predetermined amount of dilution water according to the intended freezing temperature before use. On the other hand, in JIS K 2234 (antifreeze), in consideration of prevention of metal corrosion of a cooling water system in an internal combustion engine (this is called anticorrosion), the concentration of the stock solution of antifreeze is 25 to 60% by volume. As a dilution water for performing a metal corrosion test, use is made of a prepared water (an antifreeze concentration of 30% by volume) in which ion-exchanged water contains 100 ppm each of chloride ion, sulfate ion and bicarbonate ion. Stipulated.

[0004]

However, in actual use sites, as a dilution water for adjusting the concentration of antifreeze,
In most cases, tap water is used, and sometimes the stock solution is diluted to a concentration of 25% by volume or less. Tap water is JISK 2 above depending on the place where it is used.
234 (antifreeze) contains more corrosive ions than the prepared water, and when the concentration of the stock solution is diluted to 25% by volume or less, the anticorrosion agent contained in the antifreeze becomes insufficient. Therefore, the anticorrosion effect on metals cannot be achieved. The present invention has been made in view of such circumstances, and even if diluting water containing many corrosive ions is used as diluting water for adjusting the concentration of antifreeze, the concentration of the undiluted solution is also reduced to JIS K 2234. (antifreeze)
Even if diluted to 30% by volume or less specified in
An object of the present invention is to provide an antifreeze that can prevent or suppress metal corrosion of a cooling water system in an internal combustion engine (engine).

[0005]

SUMMARY OF THE INVENTION The antifreeze of the present invention for achieving the above object can be used as a borate, a silicate, an amine or the like, which may adversely affect a cooling water system or an environment inside an internal combustion engine (engine). , And nitrites are not contained in the components at all, and the main component is glycols for preventing or suppressing the freezing of the cooling water, which does not prevent metal corrosion of the cooling water system inside the internal combustion engine (engine). As a metal corrosion inhibitor for controlling the reaction, aromatic monobasic acids, molybdates and / or tungstates, aliphatic dibasic acids, aliphatic monobasic acids, phosphoric acids, triazoles, thiazoles, And phosphonic acids. Preferably, 0.1 to 10% by weight of an aromatic monobasic acid, 0.1 to 1% by weight of a molybdate and / or tungstate, and 0.1 to 1% by weight of an aliphatic dibasic acid are added to the glycols as the main components. 1 to 3% by weight, 0.1 to 5% by weight of aliphatic monobasic acid, 0.1 to 0.5% by weight of phosphoric acids, 0.01 to 3% by weight of triazoles, and 0.01 of thiazoles. To 1% by weight, and the amount of phosphonic acid is 0.001 to 0.001%.
It is characterized by adding 0.4% by weight. At this time, the pH of the antifreeze is preferably adjusted to 6.5 to 9.0.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION The antifreeze according to the present invention contains glycols as a main component, does not contain borates, silicates, amines and nitrites in the components, and contains an aromatic monobasic acid, It is characterized by comprising a molybdate and / or tungstate, an aliphatic dibasic acid, an aliphatic monobasic acid, phosphoric acids, triazoles, thiazoles, and phosphonic acids.

[0007] The above borate has a property of corroding aluminum alloys. When heated, pH changed, or coexisted with other salts, silicate reduces the corrosion inhibiting ability for metals, They produce nitrosamines, which are considered carcinogenic when co-existing with nitrite. Therefore, the antifreeze should not contain any of the above-mentioned borates and silicates, amines, and nitrites.

[0008] As the glycols that can be used in the present invention, those conventionally used in antifreezes, such as ethylene glycol, can be used.

Further, examples of the aromatic monobasic acid which can be used in the present invention include benzoic acid, para-tert-butylbenzoic acid, trailing acid, and salts thereof. The amount of the aromatic monobasic acid added is 0.1
The range is preferably from 10 to 10% by weight, more preferably from 2 to 8% by weight. If the amount of the aromatic monobasic acid is less than 0.1% by weight, the anticorrosion performance against the metal cannot be exhibited. It is economically wasted because it cannot be expected.

Further, molybdate and tungstate may be used alone or in combination. The amount of addition of these molybdates and tungstates is in the range of 0.1 to 1% by weight, preferably 0.1% by weight.
The range of 2 to 0.8% by weight is good. If the addition amount of these molybdate and tungstate is less than 0.1% by weight,
The required anticorrosion performance against metal was not obtained.
Even if it is added more than weight%, no change is observed in the anticorrosion performance, so that it is economically wasted.

The aliphatic dibasic acids usable in the present invention include suberic acid, azelaic acid, sebacic acid,
Dodecane diacid and the like can be mentioned, and these can be used alone or as a mixture of two or more. The amount of the aliphatic dibasic acid added is preferably in the range of 0.1 to 3% by weight. More preferably, the content is 0.2 to 2% by weight.
If the amount of the aliphatic dibasic acid is less than 0.1% by weight, the anticorrosive effect on the metal cannot be expected, and if the amount is more than 3% by weight, the stability of the antifreeze solution will be deteriorated.

The aliphatic monobasic acids usable in the present invention include octanoic acid, octylic acid, isooctanoic acid, and the like.
Examples thereof include nonanoic acid, isononanoic acid, decanoic acid, isodecanoic acid, neodecanoic acid, and undecanoic acid. These may be used alone or in combination of two or more.
The aliphatic monobasic acid is present in an amount of 0.1 to 5% by weight, preferably 0.1% by weight.
It is added in the range of 5 to 4% by weight. If the content is less than 0.1% by weight, the desired anticorrosion performance against metal cannot be exhibited. Even if more than 5% by weight is added, not only the anticorrosion performance is not improved, but also the stability of the antifreeze is poor. There is a tendency.

The phosphoric acids that can be used in the present invention include phosphoric acid and salts thereof. In addition to orthophosphoric acid, first to third salts of alkali metals such as lithium, sodium and potassium can be used. These can be used alone or in combination of two or more. The amount of the phosphoric acid added is in the range of 0.1 to 0.5% by weight, preferably 0.1 to 0.3% by weight. If the amount of the phosphoric acid is less than 0.1% by weight, the anticorrosion effect on the metal cannot be expected. If the amount is more than 0.5% by weight, the anticorrosion effect is improved. This is not preferable because it may cause eutrophication of the food and may adversely affect the environment.

The triazoles usable in the present invention include benzotriazole, tolyltriazole,
These salts can be used, and these can be used alone or in combination of two or more. The amount of the triazole added is in the range of 0.01 to 3% by weight, preferably in the range of 0.3 to 2% by weight. If the amount of the triazole added is less than 0.01% by weight, the anticorrosion performance against metal cannot be exhibited and 3% by weight
Even if more is added, no further change is observed in the anticorrosion effect, so that it is useless.

The thiazoles usable in the present invention include mercaptobenzothiazole and salts thereof. The thiazoles may be used in a very small amount, such as 0.0.
It is added in the range of 1 to 1% by weight, preferably 0.01 to 0.5% by weight. However, if the addition amount is less than 0.01% by weight, the desired anticorrosion performance against metal cannot be obtained, and even if more than 1% by weight is added, no further change in the anticorrosion effect is observed, and it is useless. .

The phosphonic acids that can be used in the present invention include hydroxyethanediphosphonic acid and salts thereof. In addition to hydroxyethanediphosphonic acid, alkali metals such as sodium and potassium
Fifth salts can be used, and these can be used alone or in combination of two or more. The amount of the phosphonic acid may be a very small amount, and is added in the range of 0.001 to 0.4% by weight, more preferably 0.001 to 0.3% by weight. But,
If the added amount of the phosphonic acid is less than 0.001% by weight, the desired anticorrosive performance against metal cannot be obtained. If the added amount exceeds 0.4% by weight, a cooling water system or the like inside the internal combustion engine (engine) is formed. It may adversely affect aluminum alloy and solder.

Glycols, as metal corrosion inhibitors,
The required amount of aromatic monobasic acid, molybdate and / or tungstate, and aliphatic dibasic acid, aliphatic monobasic acid, phosphoric acids, triazoles, thiazoles, and phosphonic acids are added. The pH of the antifreeze is adjusted using a normal alkali substance, preferably a hydroxide of an alkali metal salt such as sodium or potassium. p
The H adjustment range is 6.5 to 9.0, and is preferably adjusted to a range of 7.0 to 9.0. Incidentally, an antifoaming agent such as silicone oil can be added to the antifreeze.

[0018]

Next, specific examples of the antifreeze according to the present invention will be described. As shown in Table 1 below, ethylene glycol was used as glycols, and sodium benzoate and sodium p-tert-butylbenzoate (PTBBANa) were used as the aromatic monobasic acid, and sodium molybdate was used as the molybdate. , Sebacic acid and azelaic acid as aliphatic dibasic acids, octylic acid as aliphatic monobasic acids, dibasic potassium phosphate as phosphoric acids, benzotriazole and tolyltriazole as triazoles, and mercaptobenzothiazole as thiazoles Was added and hydroxyethanediphosphonic acid as phosphonic acids was added, and the pH was adjusted with 48% caustic potassium, and the corrosion effects on various metals with changes in the added amounts of each component were compared.

<Metal corrosion test method> JIS K 2234
(Antifreeze). However, the antifreeze concentration is 15
% Corrosive water (corrosion water specially prepared for testing instead of JIS water) (chlorine ion 300 ppm, sulfate ion 3
00 ppm, bicarbonate ion 130 ppm, calcium ion 80 ppm) were used as dilution water. Each antifreeze comprising the components shown in Table 1 (Examples 1 to 3, Comparative Examples 1 to
2) was diluted to 15% by volume with the above-mentioned corrosive water, and six kinds of metal test pieces consisting of an aluminum alloy casting, cast iron, steel, brass, solder, and copper were immersed in each antifreeze, and in that state, Dry air was blown at a flow rate of 100 ml / min, and the liquid temperature was maintained at 88 ± 2 ° C. for 336 hours. <Test Items> (1) Corrosion Change of Metal Specimen The corrosion change (C) of the metal specimen was determined by the following equation. C = (m1-m2) / S, where m1: weight of metal test piece before test (g) m2; weight of metal test piece after test (g) S: surface area of metal test piece (cm ² ) (2 ) Change in appearance of metal test piece The results are shown in Table 2 below.

[0020]

[Table 1]

[0021]

[Table 2]

[0022]

As is clear from Table 2 above, the antifreeze according to the present invention can be used as a dilution water for adjusting the concentration of the antifreeze, even if a dilution water containing many corrosive ions is used. Determine the concentration according to JIS K 2234 (antifreeze)
Even when diluted to 30% by volume or less (15% by volume), the effect of preventing or suppressing metal corrosion of the cooling water system in the internal combustion engine (engine) can be sufficiently exhibited.

Continuation of the front page (72) Inventor Akira Yamada 1-13-11 Yamu, Tsurumi-ku, Yokohama-shi, Kanagawa Prefecture Tanikawa Yuka Kogyo Co., Ltd. (72) Inventor Satoshi Okawa 3-20-, Nakase, Kawasaki-ku, Kawasaki-ku, Kanagawa-ken 1 Inside the Komatsu Manufacturing System Development Center (72) Koji Iijima 3-20-1 Nakase, Kawasaki-ku, Kawasaki-shi, Kanagawa Prefecture F-term in the Komatsu Manufacturing System Development Center (reference) 4K062 AA03 BA08 BA10 BB01 BB04 BB06 BB12 BB18 BB22 BB25 CA03 CA05 FA03 FA05 GA08

Claims (3)

[Claims] 1. An antifreeze containing glycols as a main component and containing no borates, silicates, amines, and nitrites in the component, comprising an aromatic monobasic acid, molybdate and / or molybdate. Tungstate and aliphatic dibasic acid,
An antifreeze comprising aliphatic monobasic acids, phosphoric acids, triazoles, thiazoles, and phosphonic acids. 2. An aromatic monobasic acid of 0.1 to 10% by weight, a molybdate and / or tungstate of 0.1 to 1% by weight, and an aliphatic dibasic acid of 0.1 to 3% by weight. %, 0.1 to 5% by weight of aliphatic monobasic acid, and 0.1% of phosphoric acid.
1 to 0.5% by weight, 0.01 to 3% by weight of triazoles, 0.01 to 1% by weight of thiazoles, and 0.001 to 0.4% by weight of phosphonic acids. The antifreeze according to claim 1, 3. The antifreeze according to claim 1, wherein the pH of the antifreeze is adjusted to 6.5 to 9.0.