JPH01261485A - Antifreeze - Google Patents

Abstract

PURPOSE:To obtain an antifreeze having an excellent ability to inhibit aluminum corrosion and contg. no amines, by adding seven particular compds. to a mixture of a glycol with water and regulating the pH value of the resultant mixture so as to fall in a particular range. CONSTITUTION:An antifreeze comprising a glycol and water is mixed with phosphoric acid (A), a dicarboxylic acid (B), a manganese compd. (C), a molybdate (D), mercaptobenzothiazole sodium (E), a nitrate (F), a benzoate (G) and a copolymer (H) derived from a polyalkylene glycol monoallyl ether (I) of formula I [wherein each of m and n is 0 or an integer, provided that m+n is 1-100; and (C2H4O) and (C3H6O) units may be bonded in any sequence], a maleic acid monomer (II) of formula II and/or a monomer (III) copolymerizable therewith thereby obtaining an antifreeze having a pH value of 6.5-9.0.

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention relates to an antifreeze solution comprising glycols, water, and a corrosion inhibitor used to prevent 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 functions of the cooling system of an automobile engine, in addition to preventing freezing and preventing rust and corrosion. (Prior Art) Conventionally, the 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 make it antifreeze. Antifreeze is used, which also has anti-corrosion properties. (Problems to be solved by the invention) - Alcohols used for boat fishing include methyl alcohol, ethyl alcohol, isopropyl alcohol, etc., and glycols include ethylene glycol, propylene glycol, hexylene glycol, glycerin, etc. 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 -
Antifreeze effect up to -37.0°C can be obtained at 150% by volume at 15.5°C. Alcohols or glycols are oxidized when they come into contact with air, and acidic alcohol or glycol oxides become subacid. Under high temperature conditions of 50 to 100°C, the production of alcohol or glycol oxides is further promoted. This acidic alcohol'
wI 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, monoisoglopanolamine, cyclohexylamine, ethylenediamine, hydrazine, pyridine, morpholine, etc. is used. Representative among these are borax, triethanolamine phosphate, sodium benzoate, sodium nitrite□, and sodium silicate. 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. It has become a problem to have one. 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. There have been no reports of this, and 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. It is therefore an object of the present invention to provide an antifreeze solution particularly characterized by aluminum corrosion protection in an amine-free composition. As a result of extensive research, the present inventors found that in an antifreeze solution consisting of glycols and water, (A) phosphoric acids, (B) dicarboxylic acids, (C) manganese compounds, <D) molybdates, and (E) mercapto. Benzothiazole soda, (F)
Nitrate, (G) Benzoate and (H) General formula (1) %Formula% (However, in the formula, m and n are 0 or a positive integer and m+n
=I N100, (02H40) unit and (03H
60) Polyalkylene glycol monoallyl ether (I>, general formula (2) % formula % [wherein R and R2 are each hydrogen or or represents a methyl group, and X and Y are each (02H
40) rJ(C3H60)qR3 (wherein R3 represents hydrogen or an alkyl group having 1 to 20 carbon atoms, p and q are 0 or a positive integer, P+q=O to 100, (CHO) unit, The maleic acid monomer (It ) and/or a copolymer derived from monomer (III) copolymerizable with these, and the object of the present invention is achieved by having a pH in the range of 6.5 to 9.0. I was able to do that. (Means for Solving the Problems) The present invention provides an antifreeze solution comprising glycols and water, (A) phosphoric acids, (B) dicarboxylic acids, (C) manganese compounds, (D) molybdates, (E ) Mercaptobenzothiazole soda, (F)
Nitrate, (G) Benzoate and (H) General formula (1) % formula % (However, in the formula, m and n are O or a positive integer and m +
n = 1 to 100, (02H40) units and (
03■60) Units may be bonded in any order.) Polyalkylene glycol monoallyl ether (I) represented by the general formula (2), Rt R2 II C= C... ( 2) CO2X C02Y [However, in the formula, R and R2 each represent hydrogen or a methyl group, and X and Y each represent (C2tl 40
) p (C3He O)q R3 (however, 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 what j
), which may be bonded in the numerical order, represents a monovalent metal, a divalent metal, an ammonium group, or an organic amine group] and/or is copolymerizable with these maleic acid monomers (n) The present invention relates to an antifreeze solution containing a copolymer derived from a monomer (Il[), and having 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. The amount of dicarboxylic acid in the present invention includes oxalic acid, malonic acid,
Succinic acid, glutaric acid, adipic acid, piperic acid, speric acid, azelaic acid, cepatic acid, brassylic acid, tabucic acid can be used. Moreover, salts of these dicarboxylic acids can also be used. The amount of dicarbon #IM added is 0.05 to 1.0% by weight, preferably 0.1 to 0.
．． It is in the range of 7% by weight. Manganese compounds of the present invention include manganese oxide, manganese hydroxide, manganic acid, potassium permanganate, sodium permanganate, lithium permanganate, magnesium permanganate, manganese chromate, manganese borate, manganese fluoride, and manganese chloride. , manganese bromide, manganese iodide, manganese carbonate, manganese nitrate, manganese oxide,
Manganese sulfate, manganese ammonium sulfate, ah-ramann, manganese hydrogen phosphate, manganese dihydrogen phosphate, manganese ammonium phosphate, manganese formate, manganese acetate, manganese oxalate, manganese butyrate, manganese lactate, manganese malonate, manganese tartrate, manganese oparate , manganese glycerate, manganese valerate, manganese maleate, manganese oleate, citric acid, manganese iron citrate, manganese benzoate, manganese salicylate, manganese glutamate, and the like can be used. The amount of the manganese compound of the present invention added is 0.0001 to 0.050% by weight, preferably 0.00% by weight, based on the stock solution of antifreeze.
It is in the range of 5 to 0.020% by weight. As the molybdate of the present invention, sodium molybdate and potassium molybdate are used. The amount of molybdate of the present invention added is in the range of 0.10 to 1.0% by weight, preferably 0.3 to 0.7% by weight, based on the stock solution of antifreeze. The amount of mercagutobenzothiazole soda of the present invention added is in the range of 0.05 to 0.70% by weight, preferably 0.1 to 0.50% by weight, based on the stock solution of antifreeze. 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 0.50% 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 (1), a maleic acid monomer (n), and a monomer copolymerizable with these (■) can be used. , preferably general formula (1), CH2=CH1...(1) CHO(C,,H40), (C3H60). (However, in the formula, m and n are 0 or positive integers, and m + n = 1 ~
100, and (C2■40) units and (C3H60) units may be bonded in any order.) Polyalkylene glycol monoallyl ether (I), general formula (2), R1R2 C =C...(2) C02X C02Y [However, in the formula, R and R2 each represent hydrogen or a methyl group, and X and Y each represent (C2H40),
(03H60) CJR3 (where R3 represents hydrogen or an alkyl group having 1 to 20 carbon atoms, ρ and q are O or a positive integer, p-1-q=0 to 100, (C
HO) unit and (03■60) unit may be bonded in any order, ) represents a -valent metal, divalent metal, ammonium group or organic amine group. It is a copolymer derived from the monomer (II) and/or the monomer (I[[) copolymerizable with the monomer (II). Polyalkylene glycol monoallyl ether is KOH
It can be synthesized by a known method of directly adding ethylene oxide and/or propylene oxide to allyl alcohol using an alkali such as NaOH as a 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 these acids; is a positive integer, p+q=o~1
00, and the (03■60) unit and (02H40) unit may be combined in any order. For example, secondary alcohol ethoxylate monomerate can be preferably used. Moreover, one or more of these can be used. In addition, monomers copolymerizable with these (I [ Examples include salts and 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., and one of these Alternatively, 2N or more can be used. The copolymer contains polyalkylene glycol monoallyl ether (■), a maleic acid monomer (It), and/or a 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), (ff) and (III) is 100 mol %). To produce a copolymer, a polymerization initiator is used to
The body components may be copolymerized. Copolymerization can be carried out by methods such as polymerization in a solvent or bulk polymerization. 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, and isopropyl alcohol; benzene, toluene, xylene, and cyclohexane. , aromatic or aliphatic hydrocarbons such as n-hexane; ethyl acetate; ketone compounds such as acetone and methyl alcohol. 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, an accelerator such as sodium hydrogen sulfite can also be used in combination. 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 may be used in combination. Furthermore, when a water-lower alcohol mixed heating medium is used, it can be used by appropriately selecting 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 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, Preferred examples include chlorides and carbonates; ammonia; and organic amines. 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 (■) and maleic acid monomer (II) contained in the antifreeze of the present invention
A copolymer derived from the monomer (II[) copolymerizable with these has a corrosion-inhibiting effect on iron-based materials and a corrosion-inhibiting effect on aluminum-based materials. Thus, the antifreeze of the present invention overcomes the problems associated with automotive antifreeze containing phosphates. 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 copolymerizable with these (DI) 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. Normal basic substances can be used to adjust the pH of antifreeze, but
Preferably, hydroxides of alkali metals such as lithium, sodium, and potassium are 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,
Antifoaming agents such as higher fatty acid esters can be added. (Function) As is clear from the results of Examples and Comparative Examples described later, the antifreeze solution of the present invention contains (A) phosphoric acids, (B) dicarboxylic acids, and (C) manganese in an antifreeze solution consisting of glycols and water. Compound, (D) molybdate, (E) mercaptobenzothiazole soda (F)
Nitrate (G) Benzoate and (H) General formula (1) % formula % (However, in the formula, m and n are 0 or a positive integer, and m+n
= 1 to 100, (021140) unit and (03H
60) Units may be combined in any order. ) Polyalkylene glycol monoallyl ether (I) represented by the general formula (2), R, R2 C= C... (2) I C02X C02Y [wherein R and R2 are each hydrogen or a methyl group , and X and Y are each (02H
40). (C3I+60)qR3 (R3 represents hydrogen or an alkyl group having 1 to 20 carbon atoms, P and q are 0 or a positive integer, p+q=o to 100, (02 to 140) unit and (03゛H60) ) unit may be bonded in any order, ) represents a monovalent metal, a divalent metal, an ammonium group, or an organic amine group. Or, by containing a copolymer derived from monomer (III) copolymerizable with these, and having a pH in the range of 6.5 to 9.0, the 1g anticorrosive effect on aluminum is significantly improved. It is something. (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.

[A] Metal corrosion test method [JIS-2234 (antifreeze). Using test pieces of aluminum casting, cast iron, steel, brass, solder, and other metals, mixed water (148 mg of sodium sulfate,
165 mg of sodium chloride and 13 mg of sodium bicarbonate
8mg dissolved in 1 tsp of distilled water) diluted to 30% by volume with antifreeze solution, and dried air 100±10ml/l.
While feeding at a flow rate of 1 inch, increase the antifreeze temperature to 88±2
The mass of each metal piece was measured before and after the test after being held at °C for 672 hours to determine the change in mass. The change in mass of each metal was determined from the following equation. C= (m2-m1)/Swhere, C: Change in mass (mg/a&)m1:
Mass of test piece before test (mg) m2: Mass of test piece after test (mg) S: Total surface area of test piece before test (ad) [B] Heat transfer surface corrosion test method (1) Apparatus The test was carried out using an apparatus in which the upper surface of a disk-shaped test piece was in contact with the antifreeze solution, and the lower surface could be heated by a heater, so that heat was transferred to the antifreeze solution via the test piece. (2) Test method ■ The test piece is polished with #320 water-resistant abrasive paper so that it becomes flat. ■ Prepare the test solution to 25% by volume with distilled water or pure water. Sodium chloride is added to this solution to give a concentration of 1100 pp as chlorine ions. ■ After injecting the sample into the device, 0.5Kg/aG with air
Pressure is applied. ■ After the test, remove any deposits from the test piece, dry it, and weigh it accurately. (3) Test conditions Test piece: Aluminum casting (AC2A) Test piece temperature: 135 parts 1°C Antifreeze concentration = 25% by volume aqueous solution Antifreeze liquid volume
: 500oo1 test time : 16
8 hours (continuous) (4) Test item ■ Appearance of test piece ■ Change in mass of test piece The change in mass was determined from the following equation. C= (m2-m1)/Swhere, C: Change in mass (mg/cd)m
1: Mass of test piece before test (mg) m 2:
Mass of test piece after test 0 (mg) S: Total surface area of test piece before test (j) Reference example 1 [Preparation of copolymer (1)] Thermometer, stirrer, dropping funnel, gas introduction pipe and reflux In a glass reaction vessel equipped with a condenser, 334 parts of polyethylene glycol monoallyl ether (containing an average of 5 ethylene oxide units per molecule) and 10 parts of water were added.
0 part was charged, the inside of the reaction vessel was purged with nitrogen while stirring, and heated to 95°C in a nitrogen atmosphere. Then maleic acid 13
9.3 parts and 14.2 parts of ammonium persulfate were added to 22 parts of water.
A 5 part aqueous solution was added over 120 minutes. After the addition was complete, 14.2 parts of a 20% aqueous ammonium per-FaD solution was added over 20 minutes. After completion of addition, 95°C for 100 minutes
The temperature inside the reaction vessel was maintained to complete the polymerization reaction, and a copolymer aqueous solution was obtained.Next, a 40% aqueous solution of caustic soda was added to neutralize the solution, and the sodium salt of copolymer (1) (hereinafter referred to as copolymer) was prepared. Polymer (1) is abbreviated as Na salt. ) An aqueous solution was obtained. 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)] In a glass reaction vessel equipped with a thermometer, a stirrer, a dropping funnel, a gas inlet tube, and a reflux condenser, polyethylene glycol monoallyl ether (5 molecules per molecule on average) was added. (containing ethylene oxide units) and 88.5 parts of water,
The interior of the reaction vessel was replaced with nitrogen while stirring, and the temperature was increased to 95% in a nitrogen atmosphere.
heated to ℃. Thereafter, an aqueous solution of 139.3 parts of maleic acid and 11 parts of ammonium persulfate dissolved in 209 parts of water and 2 parts of styrene were added in parallel over 120 minutes. After the addition was completed, 27.8 parts of a 20% ammonium persulfate aqueous solution was further added in 60 minutes.
The polymerization reaction was completed while maintaining the temperature in the reaction vessel at 0.degree. C. to obtain a copolymer (2). Then, a 40% by weight aqueous solution of caustic soda was added to neutralize the mixture to obtain an aqueous solution of copolymer (2). This copolymer (2
) had a pH of 9.5 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. After the addition was completed, 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.
A 0% caustic soda aqueous solution was added to neutralize the mixture 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 centiboise. 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. [A] Metal corrosion test [B] Heat transfer surface corrosion test results are shown in Table-1. Comparative Examples 1-8 Samples prepared at the blending ratios shown in Table 1 were tested in the same manner as Examples 1-7. The results were as shown in Table-1. (Effect of the invention) In the antifreeze solution comprising glycols and water of the present invention, (A> phosphoric acids, (B) dicarboxylic acids, (C) manganese compound, (D) molybdate, (E) mercagutobenzothiazole Soda (F)
Nitrate (G) Benzoate and (H) General formula (1) % formula % (However, in the formula, m and n are 0 or a positive integer, m and n
= 1 to 100, (C2H40) unit and (C3H6
0) Units may be bonded in any order.) Polyalkylene glycol monoallyl ether (ene, general formula (2), R1R2 C= C... (2)l Co2X C02Y [However, , where R and R2 each represent hydrogen or a methyl group, and X and Y each represent (C2
(02
What kind of j1 is H40) unit and (C3H60) unit?
maleic acid monomers (II) and/or copolymerizable with these, which may be bonded in the n-order), representing monovalent metals, divalent metals, ammonium groups, or organic amine groups; A copolymer derived from monomer (III) and having a pH in the range of 6.5 to 9.0 significantly improves the corrosion prevention effect on aluminum. Patent applicant Nippon Shokuko Chemical Co., Ltd. Procedural Amendment (
Voluntary) July 22, 1986

Claims (1)

[Claims] (1) In an antifreeze solution consisting of glycols and water, (A) phosphoric acids, (B) dicarboxylic acids, (C) manganese compounds, (D) molybdates, (E) mercaptobenzothiazole soda, (F) nitrates. , (G) Benzoate and (H) 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) unit 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.