FUNCTIONAL FLUID COMPOSITIONS

Abstract

The present invention relates to a functional fluid composition comprising a glycol as a base material and a diamine-based noise reducer. According to the present invention as such, the functional fluid composition comprising a glycol as a base material and a diamine-based noise reducer represented by chemical formula 1 has an excellent noise reducing effect. In addition, the functional fluid composition of the present invention has an excellent metal corrosion inhibiting effect even, by using a diamine-based compound as a noise reducer, when a metal corrosion inhibitor composed of a triazole-based compound without including an amine-based compound is used as a metal corrosion inhibitor.

Claims

1. A functional fluid composition comprising a glycol as a base material, the composition comprising a diamine-based noise reducer represented by chemical formula 1 below: ##STR00013## wherein in chemical formula 1, X is an integer of 1 or greater; and Y and Z are 0 or an integer of 1 or greater, the weight average molecular weight of the compound represented by chemical formula 1 being 400 or more.

2. The functional fluid composition of claim 1, wherein the weight average molecular weight of the compound represented by chemical formula 1 is equal to or more than 400 and equal to or less than 5000.

3. The functional fluid composition of claim 1, wherein the weight average molecular weight of the compound represented by chemical formula 1 is equal to or more than 600 and equal to or less than 5000.

4. The functional fluid composition of claim 1, wherein the diamine-based noise reducer of chemical formula 1 is comprised in a content of 0.05-5.0 wt % based on the total weight of the functional fluid composition.

5. The functional fluid composition of claim 1, wherein the diamine-based noise reducer of chemical formula 1 is comprised in a content of 0.1-5.0 wt % based on the total weight of the functional fluid composition.

6. The functional fluid composition of claim 1, wherein the diamine-based noise reducer of chemical formula 1 is comprised in a content of 0.2-5.0 wt % based on the total weight of the functional fluid composition.

7. The functional fluid composition of claim 1, wherein the composition further comprises at least one additive selected from a group consisting of a metal corrosion inhibitor and an antioxidant.

8. The functional fluid composition of claim 7, wherein the metal corrosion inhibitor is a triazole-based metal corrosion inhibitor and does not comprise an amine-based metal corrosion inhibitor.

9. The functional fluid composition of claim 1, wherein in chemical formula 1, Y=0 and Z=0, the average molecular weight of the compound represented by chemical formula 1 being 400 or more.

10. The functional fluid composition of claim 9, wherein the weight average molecular weight is equal to or more than 400 and equal to or less than 5000.

11. The functional fluid composition of claim 9, wherein the weight average molecular weight is equal to or more than 600 and equal to or less than 5000.

12. The functional fluid composition of claim 9, wherein the diamine-based noise reducer of chemical formula 1 is comprised in a content of 0.05-5.0 wt % based on the total weight of the functional fluid composition.

13. The functional fluid composition of claim 9, wherein the diamine-based noise reducer of chemical formula 1 is comprised in a content of 0.1-5.0 wt % based on the total weight of the functional fluid composition.

14. The functional fluid composition of claim 9, wherein the diamine-based noise reducer of chemical formula 1 is comprised in a content of 0.2-5.0 wt % based on the total weight of the functional fluid composition.

15. The functional fluid composition of claim 9, wherein the composition further comprises at least one additive selected from a group consisting of a metal corrosion inhibitor and an antioxidant.

16. The functional fluid composition of claim 15, wherein the metal corrosion inhibitor is a triazole-based metal corrosion inhibitor and does not comprise an amine-based metal corrosion inhibitor.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0041] FIG. 1 shows images illustrating a structure of a noise test device.

[0042] FIG. 2 shows the analysis of a sound waveform and a sound pressure level (dB) of the noise in examples and test example 1.

[0043] FIG. 3 shows the analysis of a sound waveform and a sound pressure level (dB) of a noise in examples and test example 2.

[0044] FIG. 4 shows the analysis of a sound waveform and a sound pressure level (dB) of a noise in examples and test example 3.

[0045] FIG. 5 shows the analysis of a sound waveform and a sound pressure level (dB) of a noise in examples and test example 4.

[0046] FIG. 6 shows the analysis of a sound waveform and a sound pressure level (dB) of a noise in examples and test example 5.

[0047] FIG. 7 shows the analysis of a sound waveform and a sound pressure level (dB) of a noise in examples and test example 6.

MODE FOR CARRYING OUT THE INVENTION

[0048] Hereinafter, the present invention will be described in detail with reference to examples. These examples are only for illustrating the present invention more specifically, and it will be apparent to those skilled in the art that the scope of the present invention is not limited by these examples.

Examples and Test Example 1

[0049] (1) Preparation of Functional Fluid Composition

[0050] Functional fluid compositions of examples 1-1 to 1-5 and comparative examples 1-1 to 1-4 were prepared by using ingredients and compositional ratios thereof shown in table 1-1.

TABLE-US-00001 TABLE 1-1 Composition Example 1-1 Example 1-2 Example 1-3 Example 1-4 Example 1-5 Polyalkylene glycol 5 5 5 5 5 Polyethylene glycol 14 14 14 14 14 monomethylether Polyethylene glycol 13 13 13 13 13 monobutylether Triethylene glycol 11.05 11 9.1 6.1 4.1 monomethylether Boric acid ester compound 53.4 53.4 53.4 53.4 53.4 Benzotriazole 0.5 0.5 0.5 0.5 0.5 Mercapto benzotriazole 0.4 0.4 0.4 0.4 0.4 BHT 0.5 0.5 0.5 0.5 0.5 Cyclohexylamine 0.6 0.6 0.6 0.6 0.6 Dibutylamine 1.5 1.5 1.5 1.5 1.5 Diamine-based noise reducer 0.05 0.1 0.2 2 5 Comparative Comparative Comparative Comparative Composition example 1-1 example 1-2 example 1-3 example 1-4 Polyalkylene glycol 5 5 5 5 Polyethylene glycol 14 14 14 14 monomethylether Polyethylene glycol 13 13 13 13 monobutylether Triethylene glycol 11.1 8.2 13.2 14.6 monomethylether Boric acid ester compound 53.4 53.4 53.4 53.4 Benzotriazole 0.5 0.5 0.5 Mercapto benzotriazole 0.4 0.4 0.4 BHT 0.5 0.5 0.5 Cyclohexylamine 0.6 Dibutylamine 1.5 Diamine-based noise reducer 2

[0051] Meanwhile, the diamine-based noise reducer employed a diamine-based compound represented by chemical formula 2 below and having a molecular weight of 230 Mw.

##STR00007##

[0052] (2) Noise Test and Metal Corrosion Test

[0053] For a noise test, a noise test device shown in FIG. 1 was manufactured, and the noise level was evaluated while a brake pedal was repeatedly operated/returned.

[0054] The noise test device shown in the images of FIG. 1 is composed of: a booster unit which generates braking force by an operation of a brake pedal provided at one side of a vehicle driver seat; a master cylinder which receives the amplified force from the booster unit to generate a brake hydraulic pressure; wheel cylinders that are respectively installed on front and rear wheels to brake a car by the brake hydraulic pressure generated in the master cylinder; and an oil storage tank which supplies a brake fluid to the master cylinder and stores a brake fluid returned from the wheel cylinders. Meanwhile, the brake fluid means a functional fluid composition.

[0055] The noise test device was used to measure the level of noise, and the level of noise was scored according to the evaluation criteria in Table 1-2 below. The results are shown in Table 1-3. In addition, the sound waveform and sound pressure level (dB) of a noise were analyzed (sound analysis program, WaveLab), and the results are shown in FIG. 2.

[0056] Meanwhile, the metal corrosion was evaluated according to the test method of paragraph 5.5 of KS M 2141 and the results are shown in Table 1-3.

TABLE-US-00002 TABLE 1-2 Evaluation score Noise intensity No noise Fine recognition Recognizable X Unsatisfactory

TABLE-US-00003 TABLE 1-3 Example Example Example Example 1-1 1-2 1-3 1-4 Example 1-5 Noise X X X Metal Good Good Good Good Good corrosion Comparative Comparative Comparative Comparative example 1-1 example 1-2 example 1-3 example 1-4 Noise X X Metal Good Good Cast iron Steel, corrosion corrosion cast iron corrosion

Examples and Test Example 2

[0057] (1) Preparation of Functional Fluid Composition

[0058] Functional fluid compositions of examples 2-1 to 2-5 and comparative examples 2-1 to 2-4 were prepared by using ingredients and compositional ratios thereof shown in table 2-1.

TABLE-US-00004 TABLE 2-1 Composition Example 2-1 Example 2-2 Example 2-3 Example 2-4 Example 2-5 Polyalkylene glycol 5 5 5 5 5 Polyethylene glycol 14 14 14 14 14 monomethylether Polyethylene glycol monobutylether 13 13 13 13 13 Triethylene glycol monomethylether 11.05 11 9.1 6.1 4.1 Boric acid ester compound 53.4 53.4 53.4 53.4 53.4 Benzotriazole 0.5 0.5 0.5 0.5 0.5 Mercapto benzotriazole 0.4 0.4 0.4 0.4 0.4 BHT 0.5 0.5 0.5 0.5 0.5 Cyclohexylamine 0.6 0.6 0.6 0.6 0.6 Dibutylamine 1.5 1.5 1.5 1.5 1.5 Diamine-based noise reducer 0.05 0.1 0.2 2 5 Comparative Comparative Comparative Comparative Composition example 2-1 example 2-2 example 2-3 example 2-4 Polyalkylene glycol 5 5 5 5 Polyethylene glycol 14 14 14 14 monomethylether Polyethylene glycol monobutylether 13 13 13 13 Triethylene glycol monomethylether 11.1 8.2 13.2 14.6 Boric acid ester compound 53.4 53.4 53.4 53.4 Benzotriazole 0.5 0.5 0.5 Mercapto benzotriazole 0.4 0.4 0.4 BHT 0.5 0.5 0.5 Cyclohexylamine 0.6 Dibutylamine 1.5 Diamine-based noise reducer 2

[0059] Meanwhile, the diamine-based noise reducer employed a diamine-based compound represented by chemical formula 2 below and having a molecular weight of 400 Mw.

##STR00008##

[0060] (2) Noise Test and Metal Corrosion Test

[0061] The noise test and the metal corrosion test were carried out by the same method and criteria as in examples and test example 1. The results are shown in Table 2-2. Meanwhile, the sound waveform and sound pressure level (dB) of a noise were analyzed (sound analysis program, WaveLab), and the results are shown in FIG. 3.

TABLE-US-00005 TABLE 2-2 Example Example Example Example 2-1 2-2 2-3 2-4 Example 2-5 Noise Metal Good Good Good Good Good corrosion Comparative Comparative Comparative Comparative example 2-1 example 2-2 example 2-3 example 2-4 Noise X X Metal Good Good Cast iron Steel, corrosion corrosion cast iron corrosion

Examples and Test Example 3

[0062] (1) Preparation of Functional Fluid Composition

[0063] Functional fluid compositions of examples 3-1 to 3-5 and comparative examples 3-1 to 3-4 were prepared by using ingredients and compositional ratios thereof shown in table 3-1.

TABLE-US-00006 TABLE 3-1 Composition Example 3-1 Example 3-2 Example 3-3 Example 3-4 Example 3-5 Polyalkylene glycol 5 5 5 5 5 Polyethylene glycol 14 14 14 14 14 monomethylether Polyethylene glycol monobutylether 13 13 13 13 13 Triethylene glycol monomethylether 11.05 11 9.1 6.1 4.1 Boric acid ester compound 53.4 53.4 53.4 53.4 53.4 Benzotriazole 0.5 0.5 0.5 0.5 0.5 Mercapto benzotriazole 0.4 0.4 0.4 0.4 0.4 BHT 0.5 0.5 0.5 0.5 0.5 Cyclohexylamine 0.6 0.6 0.6 0.6 0.6 Dibutylamine 1.5 1.5 1.5 1.5 1.5 Diamine-based noise reducer 0.05 0.1 0.2 2 5 Comparative Comparative Comparative Comparative Composition example 3-1 example 3-2 example 3-3 example 3-4 Polyalkylene glycol 5 5 5 5 Polyethylene glycol 14 14 14 14 monomethylether Polyethylene glycol monobutylether 13 13 13 13 Triethylene glycol monomethylether 11.1 8.2 13.2 14.6 Boric acid ester compound 53.4 53.4 53.4 53.4 Benzotriazole 0.5 0.5 0.5 Mercapto benzotriazole 0.4 0.4 0.4 BHT 0.5 0.5 0.5 Cyclohexylamine 0.6 Dibutylamine 1.5 Diamine-based noise reducer 2

[0064] Meanwhile, the diamine-based noise reducer employed a diamine-based compound represented by chemical formula 2 below and having a molecular weight of 2000 Mw.

##STR00009##

[0065] (2) Noise Test and Metal Corrosion Test

[0066] The noise test and the metal corrosion test were carried out by the same method and criteria as in examples and test example 1. The results are shown in Table 3-2. Meanwhile, the sound waveform and sound pressure level (decibel, dB) of a noise were analyzed (sound analysis program, WaveLab), and the results are shown in FIG. 4.

TABLE-US-00007 TABLE 3-2 Example Example Example Example 3-1 3-2 3-3 3-4 Example 3-5 Noise Metal Good Good Good Good Good corrosion Comparative Comparative Comparative Comparative example 3-1 example 3-2 example 3-3 example 3-4 Noise X X Metal Good Good Cast iron Steel, corrosion corrosion cast iron corrosion

Examples and Test Example 4

[0067] (1) Preparation of Functional Fluid Composition

[0068] Functional fluid compositions of examples 4-1 to 4-5 and comparative examples 4-1 to 4-4 were prepared by using ingredients and compositional ratios thereof shown in table 4-1.

TABLE-US-00008 TABLE 4-1 Exam- Exam- Exam- Exam- Exam- Composition ple 4-1 ple 4-2 ple 4-3 ple 4-4 ple 4-5 Polyalkylene glycol 5 5 5 5 5 Polyethylene glycol 14 14 14 14 14 monomethylether Polyethylene glycol 13 13 13 13 13 monobutylether Triethylene glycol 11.05 11 9.1 6.1 4.1 monomethylether Boric acid ester 53.4 53.4 53.4 53.4 53.4 compound Benzotriazole 0.5 0.5 0.5 0.5 0.5 Mercapto benzotriazole 0.4 0.4 0.4 0.4 0.4 BHT 0.5 0.5 0.5 0.5 0.5 Cyclohexylamine 0.6 0.6 0.6 0.6 0.6 Dibutylamine 1.5 1.5 1.5 1.5 1.5 Diamine-based noise 0.05 0.1 0.2 2 5 reducer Compar- Compar- Compar- Compar- ative ative ative ative example example example example Composition 4-1 4-2 4-3 4-4 Polyalkylene glycol 5 5 5 5 Polyethylene glycol 14 14 14 14 monomethylether Polyethylene glycol 13 13 13 13 monobutylether Triethylene glycol 11.1 8.2 13.2 14.6 monomethylether Boric acid ester 53.4 53.4 53.4 53.4 compound Benzotriazole 0.5 0.5 0.5 Mercapto benzotriazole 0.4 0.4 0.4 BHT 0.5 0.5 0.5 Cyclohexylamine 0.6 Dibutylamine 1.5 Diamine-based noise 2 reducer

[0069] Meanwhile, the diamine-based noise reducer employed a diamine-based compound represented by chemical formula 2 below and having a molecular weight of 4000 Mw.

##STR00010##

[0070] (2) Noise Test and Metal Corrosion Test

[0071] The noise test and the metal corrosion test were carried out by the same method and criteria as in examples and test example 1. The results are shown in Table 4-2. Meanwhile, the sound waveform and sound pressure level (dB) of a noise were analyzed (sound analysis program, WaveLab), and the results are shown in FIG. 5.

TABLE-US-00009 TABLE 4-2 Example Example Example Example 4-1 4-2 4-3 4-4 Example 4-5 Noise Metal Good Good Good Good Good corrosion Comparative Comparative Comparative Comparative example 4-1 example 4-2 example 4-3 example 4-4 Noise X X Metal Good Good Cast iron Steel, corrosion corrosion cast iron corrosion

Examples and Test Example 5

[0072] (1) Preparation of Functional Fluid Composition

[0073] Functional fluid compositions of examples 5-1 to 5-5 and comparative examples 5-1 to 5-4 were prepared by using ingredients and compositional ratios thereof shown in table 5-1.

TABLE-US-00010 TABLE 5-1 Exam- Exam- Exam- Exam- Exam- Composition ple 5-1 ple 5-2 ple 5-3 ple 5-4 ple 5-5 Polyalkylene glycol 5 5 5 5 5 Polyethylene glycol 14 14 14 14 14 monomethylether Polyethylene glycol 13 13 13 13 13 monobutylether Triethylene glycol 11.05 11 9.1 6.1 4.1 monomethylether Boric acid ester 53.4 53.4 53.4 53.4 53.4 compound Benzotriazole 0.5 0.5 0.5 0.5 0.5 Mercapto benzotriazole 0.4 0.4 0.4 0.4 0.4 BHT 0.5 0.5 0.5 0.5 0.5 Cyclohexylamine 0.6 0.6 0.6 0.6 0.6 Dibutylamine 1.5 1.5 1.5 1.5 1.5 Diamine-based noise 0.05 0.1 0.2 2 5 reducer Compar- Compar- Compar- Compar- ative ative ative ative example example example example Composition 5-1 5-2 5-3 5-4 Polyalkylene glycol 5 5 5 5 Polyethylene glycol 14 14 14 14 monomethylether Polyethylene glycol 13 13 13 13 monobutylether Triethylene glycol 11.1 8.2 13.2 14.6 monomethylether Boric acid ester 53.4 53.4 53.4 53.4 compound Benzotriazole 0.5 0.5 0.5 Mercapto benzotriazole 0.4 0.4 0.4 BHT 0.5 0.5 0.5 Cyclohexylamine 0.6 Dibutylamine 1.5 Diamine-based noise 2 reducer

[0074] Meanwhile, the diamine-based noise reducer employed a diamine-based compound represented by chemical formula 1 below and having a molecular weight of 600 Mw.

##STR00011##

[0075] (2) Noise Test and Metal Corrosion Test

[0076] The noise test and the metal corrosion test were carried out by the same method and criteria as in examples and test example 1. The results are shown in Table 5-2. Meanwhile, the sound waveform and sound pressure level (dB) of a noise were analyzed (sound analysis program, WaveLab), and the results are shown in FIG. 6.

TABLE-US-00011 TABLE 5-2 Example Example Example Example 5-1 5-2 5-3 5-4 Example 5-5 Noise Metal Good Good Good Good Good corrosion Comparative Comparative Comparative Comparative example 5-1 example 5-2 example 5-3 example 5-4 Noise X X Metal Good Good Cast iron Steel, corrosion corrosion cast iron corrosion

Example and Test Example 6

[0077] (1) Preparation of Functional Fluid Composition

[0078] Functional fluid compositions of examples 6-1 to 6-5 and comparative examples 6-1 to 6-4 were prepared by using ingredients and compositional ratios thereof shown in table 6-1.

TABLE-US-00012 TABLE 6-1 Exam- Exam- Exam- Exam- Exam- Composition ple 6-1 ple 6-2 ple 6-3 ple 6-4 ple 6-5 Polyalkylene glycol 5 5 5 5 5 Polyethylene glycol 14 14 14 14 14 monomethylether Polyethylene glycol 13 13 13 13 13 monobutylether Triethylene glycol 11.05 11 9.1 6.1 4.1 monomethylether Boric acid ester 53.4 53.4 53.4 53.4 53.4 compound Benzotriazole 0.5 0.5 0.5 0.5 0.5 Mercapto benzotriazole 0.4 0.4 0.4 0.4 0.4 BHT 0.5 0.5 0.5 0.5 0.5 Cyclohexylamine 0.6 0.6 0.6 0.6 0.6 Dibutylamine 1.5 1.5 1.5 1.5 1.5 Diamine-based noise 0.05 0.1 0.2 2 5 reducer Compar- Compar- Compar- Compar- ative ative ative ative example example example example Composition 6-1 6-2 6-3 6-4 Polyalkylene glycol 5 5 5 5 Polyethylene glycol 14 14 14 14 monomethylether Polyethylene glycol 13 13 13 13 monobutylether Triethylene glycol 11.1 8.2 13.2 14.6 monomethylether Boric acid ester 53.4 53.4 53.4 53.4 compound Benzotriazole 0.5 0.5 0.5 Mercapto benzotriazole 0.4 0.4 0.4 BHT 0.5 0.5 0.5 Cyclohexylamine 0.6 Dibutylamine 1.5 Diamine-based noise 2 reducer

[0079] Meanwhile, the diamine-based noise reducer employed a diamine-based compound represented by chemical formula 1 below and having a molecular weight of 900 Mw.

##STR00012##

[0080] (2) Noise Test and Metal Corrosion Test

[0081] The noise test and the metal corrosion test were carried out by the same method and criteria as in examples and test example 1. The results are shown in Table 6-2. Meanwhile, the sound waveform and sound pressure level (dB) of a noise were analyzed (sound analysis program, WaveLab), and the results are shown in FIG. 7.

TABLE-US-00013 TABLE 6-2 Example Example Example Example 6-1 6-2 6-3 6-4 Example 6-5 Noise Metal Good Good Good Good Good corrosion Comparative Comparative Comparative Comparative example 6-1 example 6-2 example 6-3 example 6-4 Noise X X Metal Good Good Cast iron Steel, corrosion corrosion cast iron corrosion

[0082] For reference, the method for evaluating metal corrosion according to the test method of paragraph 5.5 of KS M 2141 is as follows.

[0083] (1) Corrosion Test Method

[0084] Metal test pieces (tinned iron, steel, aluminum, cast iron, brass, copper) polished with 320A silicon carbide to avoid surface impressions were prepared with a surface area of 25.5 cm.sup.2. The respective metal pieces were weighed to 0.1 mg, and then were brought into electric contact with each other through bolt assembling.

[0085] The assembled metal pieces and a standard SBR cup were placed in a 475 ml-volume glass bottle, and a brake fluid mixed with 5 vol % of distilled water was allowed to fill 400 ml. The glass bottle was tightly closed with a tin-plated iron lid having a ventilation hole (0.80.1) mm in diameter, and then placed in an oven at 1002 C. for 1202 hours.

[0086] The bottle was cooled at room temperature for 60-90 minutes, and then the metal pieces were immediately taken out, washed water, and then wiped with a cloth wetted with 95% ethanol one by one. The metal pieces were inspected for corrosion or impression marks.

[0087] Meanwhile, the metal test pieces and the brake fluid test cup used in the corrosion test are shown in tables 7 and 8 below.

TABLE-US-00014 TABLE 7 Metal test pieces listed in Annex B of KS M 2141 Copper plate Material General material Surface corrosion standard data Dimension Thickness requirements Tinned ASTM A-624 Tinplate, Electrolytic As As sheared. iron Fed. Spec. bright sr type Mr. T-3 purchased Clean and uniform QQ-T-425A No. 2885 IB tinning Steel SAE 1018 Low carbon sheet, 0.2 cm Edge machined to Cold rolled remove shearing Hardness 40HB-72HB marks, clean uniform surfaces Aluminum SAE AA 2024 Wrought aluminum 0.2 cm Edge machined to alloy, temper T-3, remove shearing hardness: 75B marks, clean typical uniform surfaces Cast iron SAE G 3000 automotive cast Length 8 cm 0.4 cm Surface grind iron. Shall be free Width 1.3 cm sides to from shrinkage Surface area dimension using cavities, porosity or (25 2) cm.sup.2 well-dressed No. any other defects 80 alundum detrimental to wheel, clean specification use of uniform surfaces the material. Hardness: 86HB-98HB Brass SAE CA 260 wrought alloy- 0.2 cm Edge machined to yellow brass rolled remove shearing sheet or piece, marks, clean Hardness: 54HB-74HB uniform surfaces Copper SAE CA 114 Cold-rolled copper 0.2 cm Edge machined to sheet or piece, remove shearing Hardness: 35HB-56HB marks, clean uniform surfaces Note: Drill hole with 4 mm-5 mm in diameter and aapprox. 6 mm from one end of each piece. Holes shall be clean and free from burrs. Hardness range are commercial for the designated metals. Hardness is not specified for the tinned iron because it is not considered a practical rerquirement. Test pieces (strips) can be obtained from Society of Automotive Engineers Inc., 400 Commonwalth Drive, Warrendale, Pa. 15096, USA or Laboratoire de Recherches et de controle du caoutchouc, 12 rue Crves, 9212D montrouge, France.

TABLE-US-00015 TABLE 8 Brake fluid test cup defined in annex A of KS M 2141 Ingredient Weight ratio SBR 1503.sup.a form 100 Oil furnace black (NBS 378) 40 Zinc oxide (NBS 370) 5 Sulfur (NBS 371) 0.25 Stearic acid (NBS 372) 1 N-tertiary-butyl-2-benzothiazole sulphenamide (NBS 384) 1 Symmetrical-dibetanaphthyl-p-phenylenediamine 1.5 Dicumyl peroxide (40% on precipitated CaCO.sub.3).sup.b 4.5 Total 153.25 Note: The ingredient list (NBS . . . ) should have the same technical characteristics as ones provided by the National Bureau of Standards (U.S.A.). .sup.aPhilprene 1503 is suitable. .sup.bused within 90 days after preparation and stored at a temperature of 27 C. or less.

[0088] (2) Corrosion Evaluation Method

[0089] When the brake fluid was tested according to the corrosion test method, the weights of the test pieces were measured by the unit of 0.1 mg, and the variation (mg/cm.sup.2) was calculated according to the equation 4.

[0090] The weight change should not exhibit the corrosion exceeding the reference values shown in Table 9 below. The outer contact surface of the metal piece should not be impressed or roughened enough to be visible to the naked eye. However, the metal piece was allowed to be stained or decolorized.

[0091] The brake fluid/water mixture should not be hardened at (235) C. at the end of the test, and the formed crystalline precipitates should not stick to the wall of the glass bottle or the surface of the metal piece. The mixture should not contain 0.1 vol % or more of precipitate, and the pH of the mixture should be equal to or higher than 7.0 and equal to or lower than 11.5.

[00002]$\begin{array}{cc}\mathrm{Variation}=\frac{\mathrm{weight}.Math..Math.\mathrm{before}.Math..Math.\mathrm{test}-\mathrm{weight}.Math..Math.\mathrm{after}.Math..Math.\mathrm{test}}{\mathrm{surface}.Math..Math.\mathrm{area}}& \left[\mathrm{Equation}.Math..Math.4\right]\end{array}$

TABLE-US-00016 TABLE 9 Maximum allowable weight change Test piece (mg/cm.sup.2, surface area) Tinned iron 0.20 Steel 0.20 Aluminum 0.10 Cast iron 0.20 Brass 0.40 copper 0.40