JPH01318077A - Antifreeze - Google Patents

Abstract

PURPOSE:To obtain an antifreeze improved in corrosiveness to aluminum by mixing a glycol with water and six specified additives. CONSTITUTION:A copolymer is obtained by reacting a polyalkylene glycol monoallyl ether of formula I [wherein m and n are each >=0, m+n=1-100; the (C2H4O) units and the (C3H6O) units may be bonded in an arbitrary sequence] with a maleate monomer of formula II [wherein R1-2 are each H or CH3; X and Y are each a monovalent metal, a bivalent metal, ammonium, an organic amine or formula III; R3 is H or 1-20C alkyl; p and q are each >=0, and p+q=0-100; and the (C2H4O) units and the (C3H6O) units may be bonded in an arbitrary sequence] and/or a monomer copolymerizable therewith. An antifreeze of a pH of 6.5-9.0 is obtained by mixing a glycol with water, 0.1-5.0wt.% phosphoric acid, 0.001-0.080wt.% Mg compound, 0.05-0.70wt.% mercaptobenzothiazole sodium, 0.05-0.70wt.% nitrate, 1.0-7.0wt.% benzoate and at least 0.01wt.% copolymer obtained above.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an antifreeze solution comprising glycols, water, and a corrosion inhibitor used for preventing freezing of cooling water of a liquid-cooled internal combustion engine. More specifically, the present invention relates to an antifreeze liquid that is used as a coolant for an automobile engine and is effective in maintaining the R performance of the cooling system of an automobile engine, in addition to preventing freezing and preventing rust and corrosion.

(Prior art) Conventionally, coolant for liquid-cooled internal combustion engines, such as automobile engines, has been made mainly of alcohols or glycols to prevent freezing in the final stage, and various corrosion inhibitors have been added to this to prevent freezing. Antifreeze is used because it has both corrosion and anti-corrosion properties.

(Problems to be solved by the invention) - Methyl alcohol, ethyl alcohol, isopropyl alcohol, etc. are used as alcohols, and ethylene glycol, propylene glycol, hexylene glycol, glycerin, etc. are used alone as glycols. Or they are used in combination. Among these, antifreeze containing monoethylene glycol as a main ingredient is particularly used as a coolant in the cooling system of an automobile engine.

In the case of monoethylene glycol aqueous solution, at 30% by volume -
Anti-freeze effect up to -37.0°C can be obtained at 15.5°C and 50% by volume.

Alcohols or glycols are oxidized by contact with air, producing acidic alcohol or glycol oxides. Under high temperature conditions of 50 to 100°C, the production of alcohol or glycol oxides is further promoted. These acidic alcohols or glycols significantly accelerate the corrosion of various metals constituting the cooling system of an internal combustion engine, especially an automobile engine.

Corrosion of various metals constituting the cooling system of an internal combustion engine causes a decrease in thermal conductivity due to deposition of corrosion products or blockage of the radiator pipe, causing the engine to overheat.

Antifreeze solutions containing alcohols or glycols as their main components have a corrosion inhibitor added to them because the alcohols or glycols themselves have no anticorrosion effect.

Anticorrosive agents include borax, sodium nitrite, phosphoric acid, silicates, sodium benzoate, sodium salt of mercaptobenzothiazole, benzotriazole, methylbenzotriazole, triethanolamine, jetanolamine, monoethanolamine, triethanolamine, At least one additive of isopropanolamine, diisopropanolamine, monoiso-10panolamine, cyclohexylamine, ethylenediamine, hydrazine, pyridine, morpholine, etc. is used. Typical among these are borax, triethanolamine phosphate, sodium benzoate, sodium nitrite, and sodium gaic acid. Borax has been widely used as an effective anti-corrosion agent for cast iron engines, but in recent years, aluminum parts have been adopted as automobile parts become lighter in order to conserve resources and energy. Having one has become a problem.

When an aqueous ethylene glycol solution containing borax is used in the cooling system of an automobile engine, it can corrode the aluminum alloy that is the material of the engine's cylinder head and cylinder block, and the corrosion products can clog the radiator. Are known.

On the other hand, triethanolamine phosphate has excellent anticorrosion properties for iron-based and aluminum materials, and has been used as an anticorrosive agent in place of borax, but later, the coexistence of triethanolamine and nitrite produces nitrosamines. It has been reported that it is desirable to avoid the coexistence of amines and nitrites, and sodium benzoate alone cannot be expected to be effective enough to replace these anticorrosive agents.

On the other hand, sodium silicate is also effective as a corrosion inhibitor, but there is a problem in that sodium silicate tends to gel and separate during long-term storage.

That is, an object of the present invention is to provide an antifreeze solution that is a composition that does not contain amines and has particularly excellent aluminum corrosion resistance. As a result of extensive research, the present inventors found that in an antifreeze solution consisting of glycols and water, (A) phosphoric acids, (B) magnesium compounds, (C) mercaptobenzothiazole soda, (D>
Nitrate, (E) Benzoate and (F) -Total allowance (1) % formula % (However, in the formula, m and n are 0 or a positive integer and m+n
= 1~loo, (02■40) unit and (C3H6
0) Units may be bonded in any order.) Polyalkylene glycol monoallyl ether (I) represented by the general formula (2) % formula % [However, in the formula, R and R2 are each hydrogen or or represents a methyl group, and X and Y are each (02H
40) D(C3■60), R3 (wherein R3 represents hydrogen or an alkyl group having 1 to 20 carbon atoms, and p and q
is 0 or a positive integer, p+q=o~100, and (
02■40) units and (03H60) units may be bonded in any order, ) represents a monovalent metal, a divalent metal, an ammonium group, or an organic amine group. Monomer (II) and/or a copolymer derived from monomer (II[) copolymerizable with these, and the pH is in the range of 6.5 to 9.0. The purpose of the invention was achieved.

(Means for Solving the Problems) The present invention provides an antifreeze solution comprising glycols and water, (A) phosphoric acids, (B) magnesium compounds, (C) mercaptobenzothiazole soda, (D)
nitrate, (B) benzoate and (F) -removal allowance (1)% formula% (wherein m and n are 0 or positive integers, m = 1 to 100, and (02H40) units) (C
3H60) units may be combined in any order,
) Polyalkylene glycol monoallyl ether (I) represented by the general formula (2), R1R2 C=C...(2) (I C02X Co2Y [However, in the formula, R and R2 each represent hydrogen or a methyl group. where X and Y are each (C2■
40), (031160)qR3 (wherein, R3 represents hydrogen or an alkyl group having 1 to 20 carbon atoms, P and q are 0 or a positive integer, and P+q-0 to 100, (02H40) unit and ( C3H60) units may be bonded in any order, ), monovalent metal, divalent metal, ammonium group or organic amine group] Maleic acid-based JNmer (II) and / or a monomer copolymerizable with these (a copolymer derived from I[[), and has a pH in the range of 6.5 to 9.0. .

Examples of the phosphoric acids of the present invention include phosphoric acids and salts thereof. In addition to orthophosphoric acid, first to tertiary salts of alkali metals such as lithium, sodium, and potassium can be used. The amount added is 0.1 to 5.0 to the undiluted antifreeze solution.
% by weight, preferably 0.5-3.0% by weight.

Magnesium compounds of the present invention include magnesium oxide, magnesium hydroxide, magnesium permanganate, magnesium chromate, magnesium fluoride, magnesium iodide, magnesium carbonate, magnesium nitrate, magnesium sulfate, magnesium titanate, magnesium tungstate, and magnesium borate. , magnesium phosphate, magnesium dihydrogen phosphate, magnesium ammonium phosphate,
Magnesium formate, magnesium acetate, magnesium propionate, magnesium butyrate, magnesium valerate, magnesium laurate, magnesium stearate, magnesium oleate, magnesium glutamate, magnesium lactate, magnesium abate, magnesium malate, magnesium tartrate, magnesium hydrogen tartrate, Magnesium maleate, magnesium citrate, magnesium oxalate, magnesium malonate, magnesium sebacate, magnesium benzoate, magnesium phthalate, magnesium salicylate, magnesium mandelate, etc. can be used.

The amount of the magnesium compound of the present invention added is 0.001 to 0.080% by weight, preferably 0.0% by weight, based on the stock solution of antifreeze.
It ranges from 0.05 to 0.050% by weight.

The amount of mercaptobenzothiazole soda added in the present invention is in the range of 0.05 to 0.70% by weight, preferably O91 to 0.50% by weight, based on the stock solution of the antifreeze solution.

As the nitrate of the present invention, alkali metal salts such as sodium salts and potassium salts are used. The amount of nitrate added is 0.05 to 0.70% by weight, preferably 0.05 to 0.70% by weight based on the stock solution of antifreeze.
．． It ranges from 1 to 0,950% by weight.

As the benzoate of the present invention, alkali metal salts such as sodium salts and potassium salts are used. The amount of benzoate added is in the range of 1.0 to 7.0% by weight, preferably 2.0 to 7.0% by weight, based on the stock solution of antifreeze.

As the copolymer of the present invention, a copolymer derived from polyalkylene glycol monoallyl ether (T), a maleic acid monomer <II), and a monomer (squad) copolymerizable with these can be used. , preferably - machining allowance (1), Cl2=CH1...(1) CH20(C2H40)l(03H60). [1 (In the formula, m and n are 0 or positive integers, m + n = 1
~100, (02H40) unit and (C3■60)
The units may be bonded in any order.) Polyalkylene glycol monoallyl ether (I) represented by the Itto λ formula (2, R1R2 C=C...(2) II C02X C02Y [However, , in the formula, R and R2 each represent a hydrogen methyl group, and X and Y each represent (C2H
40) D(C3H60). R3 (however, R3 represents hydrogen or an alkyl group having 1 to 20 carbon atoms, and p and q
is O or a positive integer, p-t-q=O~100, and the (CHO) unit and the (C360) unit may be combined in any order. ), a maleic acid monomer (II) represented by -, which represents a divalent metal, an ammonium group or an organic amine group, and/or a monomer copolymerizable with these (II[) It is a copolymer made of

Polyalkylene glycol monoallyl ether (]) can be synthesized by a known method of directly adding ethylene oxide and/or propylene oxide to allyl alcohol using an alkali such as KOH or NaOH as catalyst. As long as it is represented by the above general formula, it can be used either as a single structure or as a mixture.

The maleic acid monomer (II) is represented by the above general formula, and specifically includes maleic acid, phthalic acid, citraconic acid, mesaconic acid, and monovalent metal salts of these acids.
Divalent metal salts, ammonium salts, organic amine salts and their acids with HO (C2H40). (03H60), R3 (Nadashi,
R3 represents hydrogen or an alkyl group having 1 to 20 carbon atoms, P and q are 0 or a positive integer, and P+CI=0 to 1
00, and the (C3H60) units and (02H40) units may be bonded in any order. ) can be mentioned, and for example, secondary alcohol ethoxylate monomerate can be suitably used. Moreover, one or more of these can be used.

Monomers (III) copolymerizable with these include acrylic acid, methacrylic acid, itaconic acid, crotonic acid, monovalent metal salts, divalent metal salts, ammonium salts, organic amine salts, and Examples include esters obtained from these acids and alcohols, (meth)acrylamide, vinyl acetate, propenyl acetate, aromatic vinyl compounds such as styrene and p-methylstyrene, vinyl chloride, etc. One or two of these More than one species can be used. The copolymer contains polyalkylene glycol monoallyl ether (I), maleic acid monomer (II) and/or monomer copolymerizable with these (III) in an amount of 24 to 75 mol% and 24 to 75 mol%, respectively. Mol% and 0-5
It was derived using a ratio of 0 mol% (however, the total of components (I), (n) and (II[) is 100 mol%).

To produce a copolymer, the monomer components may be copolymerized using a polymerization initiator. Copolymerization can be carried out by polymerization in a solvent, bulk polymerization, or the like.

Polymerization in a solvent can be carried out either batchwise or continuously, and the solvents used include: water, lower alcohols such as methyl alcohol, ethyl alcohol, isopropyl alcohol, benzene, toluene, xylene, cyclohexane, n - Aromatic or aliphatic hydrocarbons such as hexane; ethyl acetate; ketone compounds such as acetone and methyl ethyl ketone; and the like. From the viewpoint of the solubility of the raw material monomer and the resulting copolymer and the convenience of using the copolymer, it is preferable to use at least one selected from the group consisting of water and lower alcohols having 1 to 4 carbon atoms. Among the preferred lower alcohols having 1 to 4 carbon atoms, methyl alcohol, ethyl alcohol, and isopropyl alcohol are particularly effective.

When polymerization is carried out in an aqueous medium, a water-soluble polymerization initiator such as ammonium or alkali metal persulfate or hydrogen peroxide is used as the polymerization initiator. At this time, accelerated punishment such as sodium bisulfite may also be used. In addition, for polymerization using lower alcohols, aromatic hydrocarbons, aliphatic hydrocarbons, ethyl acetate, or ketone compounds as solvents, peroxides such as benzoyl peroxide and lauroyl peroxide, hydroperoxides such as cumene hydroperoxide; Aliphatic azo compounds such as bisisobutyronitrile are used as polymerization initiators. At this time, a promoter such as an amine compound can also be used in combination.

Furthermore, when a water-lower alcohol mixed solvent is used, it can be appropriately selected from among the various polymerization initiators or combinations of polymerization initiators and accelerators mentioned above. The polymerization temperature is appropriately determined depending on the solvent and polymerization initiator used, but it is usually carried out within the range of 0 to 120°C.

In bulk polymerization, peroxides such as benzoyl peroxide and lauroyl peroxide; hydroperoxides such as cumene hydroperoxide; and aliphatic azo compounds such as azobisisobutyronitrile are used as polymerization initiators.
It is carried out within a temperature range of 50-150°C.

The copolymer thus obtained may be used after being further neutralized with an alkaline substance if necessary. Such alkaline substances include hydroxides of -valent metals and divalent metals, Preferable examples include chlorides and carbonates; ammonia: Arisawa amine and the like.

Moreover, the molecular weight of the copolymer can be used in a wide range, but it is preferably in the range of 500 to 50,000.

Polyalkylene glycol monoallyl ether (I) and maleic acid monomer (II) contained in the antifreeze of the present invention
A copolymer derived from the monomer (III) copolymerizable with these has a corrosion inhibiting effect on iron-based materials and a corrosion-inhibiting effect on aluminum-based materials. Therefore, the antifreeze of the present invention solves the problems associated with automotive antifreeze containing phosphorus'eLtM.

The amount of the copolymer derived from the polyalkylene glycol monoallyl ether (1) of the present invention, the maleic acid monomer (n), and the monomer (III) copolymerizable with these is added to the stock solution of the antifreeze solution. It is 0.01% by weight or more.

In addition, methylbenzotriazole, benzotriazole, etc. can be used.

For adjusting the pH of the antifreeze solution, ordinary basic substances can be used, but hydroxides of alkali metals such as lithium, sodium, and potassium are preferably used.

Acidic substances such as phosphoric acid can also be used if necessary.

The pH adjustment range is 6.5 to 9.0, preferably 7.
．． It is 0 to 8.0. If the pH is higher than this range, the corrosion resistance against aluminum will be poor, and if it is lower, corrosion of iron will occur, so it should be adjusted within the above range.

The antifreeze of the present invention includes silicone oil, mineral oil, alcohol,
Defoamers such as higher fatty acid esters can be added.

(Function) As is clear from the results of Examples and Comparative Examples described below, the antifreeze solution of the present invention has a significantly improved corrosion prevention effect on aluminum.

(Example) Next, the antifreeze solution of the present invention will be described in more detail with reference to Examples, but the present invention is not limited thereto.

rA] Metal corrosion test method [JIS-2234 <antifreeze)] Using each metal test piece of aluminum casting, cast iron, steel, brass, solder, and copper, mixed water (sodium sulfate 148 mg,
165 mg of sodium chloride and 13 mg of sodium bicarbonate
8 mg dissolved in distilled water 11) diluted to 30% by volume with antifreeze solution, and dried air was added to 100 ± 10 cal.
The antifreeze temperature was held at 88±2° C. for 672 hours while pumping at a flow rate of /1 inch. The mass of each metal piece before and after the test was measured to determine the change in mass.

The change in mass of each metal was determined from the following equation.

C= (m 2 - m 1)/S where, C: Change in mass <mg, /#) m 1:
Mass of test piece before test (mg) m2: Mass of test piece after test (mg) S: Total surface area of test piece before test (-) Reference example 1 [Preparation of copolymer (1)] Temperature 334 parts of polyethylene glycol monoallyl ether (containing an average of 5 ethylene oxide units per molecule) and 100 parts of water were placed in a glass reaction vessel equipped with a meter, a stirrer, a dropping funnel, a gas introduction tube, and a reflux condenser. The inside of the reaction vessel was purged with nitrogen while stirring, and heated to 95°C in a nitrogen atmosphere. After that, an aqueous solution of 139.3 parts of maleic acid and 14.2 parts of ammonium persulfate dissolved in 225 parts of water was added for 120 minutes, and after the addition was completed, an additional 1.
4.2 parts of 20% aqueous ammonium persulfate solution was added over 20 minutes. After the addition was completed, the temperature inside the reaction vessel was maintained at 95° C. for 100 minutes to complete the polymerization reaction, and an aqueous copolymer solution was obtained. Next, a 40% aqueous solution of caustic soda was added to neutralize the mixture to obtain an aqueous solution of the sodium salt of copolymer (1) (hereinafter abbreviated as copolymer (1) Na salt).

The sodium salt aqueous solution of this copolymer (1) has a pH of 9.
5. The viscosity was 203 centiboise.

Reference Example 2 [Preparation of copolymer (2)] Polyethylene glycol monoallyl ether (5 ethylene oxide molecules per molecule on average) was placed in a glass reaction vessel equipped with a thermometer, a stirrer, a dropping funnel, a gas introduction tube, and a reflux condenser. (including units) and 88.5 parts of water,
The inside of the reaction vessel was replaced with nitrogen while stirring, and the temperature was increased to 95% in a nitrogen atmosphere.
Heated to °C. Thereafter, an aqueous solution of 139.3 parts of maleic acid and 11.1 parts of ammonium persulfate dissolved in 209 parts of water and 6.2 parts of styrene were added in parallel over 120 minutes. After the addition was complete, 27.8 parts of a 20% aqueous ammonium persulfate solution was further added over 60 minutes. After completion of addition, 90
The temperature inside the reaction vessel was maintained at 95° C. for a minute to complete the polymerization reaction, and a copolymer (2) was obtained.

Then, 40% by weight caustic soda water:Fj solution was added to neutralize the mixture to obtain an aqueous solution of copolymer (2). The aqueous solution of this copolymer (2) had p)(==(1), 5, and a viscosity of 198 centiboise.

Reference Example 3 [Preparation of copolymer (3)] Polyalkylene glycol monoallyl ether (10 molecules per molecule on average) Containing an ethylene oxide unit and two propylene oxide units>3
6 parts of 99.degree. Thereafter, an aqueous solution of 75.4 parts of maleic acid and 17.1 parts of ammonium persulfate dissolved in 113.2 parts of water was added over 120 minutes, and after the addition was complete, an additional 17.1 parts of 20
% ammonium persulfate solution was added over 20 minutes. After the addition was completed, the temperature inside the reaction vessel was maintained at 95°C for 100 minutes to complete the polymerization reaction, and an aqueous copolymer solution was obtained.
Neutralization was performed by adding 0% aqueous sodium hydroxide solution to obtain an aqueous solution of copolymer (3). This aqueous solution of copolymer (3) had a pH of 9.5 and a viscosity of 135 centivoice.

Examples 1 to 7 The formulations shown in Table 1 were dissolved in 5 parts by weight of tap water or 95 parts by weight of monoethylene glycol at the blending ratio shown in Table 1, and both solutions were mixed.

The following tests and measurements were performed on each sample.

The metal corrosion test results are shown in Table-1.

Comparative Examples 1 to 4 Samples prepared at the blending ratios shown in Table 1 were tested in the same manner as Examples 1 to 7.

The metal corrosion test results are shown in Table-1.

(Effect of the invention) In the antifreeze solution comprising glycols and water of the present invention, (A) phosphoric acids, (B) magnesium compound, (C) mercaptobenzothiazole soda, (D)
Nitrate, (E) Benzoate and (F') -Total allowance (1) % formula % (wherein m and n are 0 or positive integers and m+n
= 1 to 100, (C2H40) unit and (C31'
160) Units may be bonded in any order, polyalkylene glycol monoallyl ether (I) represented by General formula (2), R1R2 C= C...(2) C02X C02Y [However, , where R and R2 each represent hydrogen or a methyl group, and X and Y each represent (C2H
40). (C3H60)qR3 (R3 represents hydrogen or an alkyl group having 1 to 20 carbon atoms, p and q are positive integers, p+q=o to 100, (C2H4
Q unit and (C3h60) unit may be bonded in any order), represents a monovalent metal, divalent metal, ammonium group or organic amine group] A maleic acid monomer represented by (I[) and/or a copolymer derived from monomer #(III) copolymerizable with these, and has a pH in the range of 6.5 to 9.0, thereby preventing corrosion against aluminum. The effect is significantly improved.

Claims (1)

[Claims] (1) In an antifreeze solution consisting of glycols and water, (A) phosphoric acids, (B) magnesium compounds, (C) mercaptobenzothiazole soda, (D) nitrates, (E) benzoates, and (F) general Formula (1) ▲There are mathematical formulas, chemical formulas, tables, etc.▼...(1) (However, in the formula, m and n are 0 or positive integers, and m+n
= 1 to 100, and (C_2H_4O) units and (C_3H_6O) units may be combined in any order. ) Polyalkylene glycol monoallyl ether (I), general formula (2) ▲There are mathematical formulas, chemical formulas, tables, etc.▼...(2) [However, in the formula, R_1 and R_2 each represent hydrogen or a methyl group. and X and Y are each (C_2H
_4O)_p(C_3H_6O)_qR_3(R_3 represents hydrogen or an alkyl group having 1 to 20 carbon atoms, p and q are 0 or a positive integer, p+q=0 to 100, and (C_2H_4O) unit and (C_3H_6O) Units may be bonded in any order), monovalent metals, divalent metals, ammonium groups, or organic amine groups. ] A copolymer derived from the maleic acid monomer (II) and/or the monomer (III) copolymerizable with these, and has a pH of 6.5 to 9.0. Antifreeze characterized by a range.