R&D on Lubricant Oil for New Energy-Saving Drive · PDF fileR&D on Lubricant Oil for New...

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M.4.4.2

R&D on Lubricant Oil for New Energy-Saving Drive System

(Fuel conservation type new drive lubricant oil group)

Anegasaki No. 401 Laboratory: ο Masahiko Takesue, Junichi Deshimaru,

Akio Imahashi, Shigeo Hara,

Toshihiko Ichihashi, Noriyuki Imazumi,

Akihito Abe, Yukitoshi Fujinami

Sodegaura No. 402 Laboratory: Nobuaki Shimizu, Tatsuya Egawa,

Satoshi Nagao

1. Contents of R&D

1.1 R&D Objective

The R&D objective is to develop a CVT special-purpose oil of long fatigue life and of

outstanding wear resistance and heat resistance in order to secure the reliability of a new drive

system (metal belt type CVT), which is a key technology for improving fuel consumption.

Concurrently, the objective is to investigate heat resistance and lubricant oil composition, and

on fatigue life and lubricant oil composition; to search for and synthesize heat resistant and

fatigue life resistant additives; to analyze fatigue surfaces; to conduct other research and to

collect fundamental data.

1.2 R&D Targets

Current technology covering fatigue life, wear resistance and heat resistance and development

targets are presented in Table 2.1-1.

Table 2.1-1 Current Technology and Development Targets

Performance Experiment method Current technology Development target

Fatigue life Rolling fatigue life

test

IAE gear test

Contact frequency up to

fatigue life

80°C, 4.8 GPa

5×106

Experimental conditions

determined after introduction

of equipment

Contact frequency up to

fatigue life

80°C, 4.8 GPa

10×106

Double the current operation

time up to fatigue generation

Wear

resistance

Shell 4-ball test 75°C, 40 kg, 60 min

Wear scar width: 0.5 mm

100℃, 40 kg, 60 min

Wear scar width: 0.5 mm

Heat

resistance

ISOT test 150°C, 96 hr

Increase in total acid

number: 3.0 or less

Percentage increase in

viscosity: 20% or less

150°C, 192 hr

Increase in total acid

number: 3.0 or less

Percentage increase in

viscosity: 20% or less

2000

2

Of these, technologies for satisfying fatigue life or heat resistance targets separately will be

completed in the year 2001. Technologies satisfying all of the above targets will be completed

by 2002, the final year. In 1999, the performances of various types of additives with different

structures will be investigated and used as fundamental data from the year 2000.

1.3 Contents of R&D in 1999

1.3.1 Sample oil

With the objective of collecting fundamental data for completion of a high-performance belt type

CVT oil, the performances of various types of additives were investigated in relation to fatigue

life, heat resistance, friction and wear characteristics, etc. In order to evaluate the

performances of single additives in the investigation, two types of sample oil were prepared: the

“PEC99/A series” in which various types of additives were added to paraffin base oil (P150),

and the “PEC99/B series” in which Ca sulfonate and dispersant are added to paraffin base oil

(P150) in consideration of CVT oil, and this is taken as a base to which various additives are

added.

1.3.2 Evaluation research on fatigue life

Using a rolling fatigue life tester, the fatigue life of the PEC99/B series was evaluated. In

addition, rolling fatigue surface underwent EPMA analysis and the relationship to fatigue life was

considered.

Test equipment: Rolling fatigue tester (Okamoto Koki Co., Ltd. : CRT-RIG)

Test conditions: 1500 rpm, 3000 N(Pmax 4.78 Gpa), 80°C

Test plate: SUJ-2, HRC 60±2, Surface roughness 1.0 µm, 0.5 µm, Rz

Test steel ball: φ9.525 mm (for NSK 51305), 3 balls used in 1 set

An outline of the test equipment is shown in Figure 2.1-1.

Load

Test steel ball

Test plate

Retainer (fixed)

Figure 2.1-1 Outline of rolling fatigue test

1.3.3 Evaluation research on heat resistance

For evaluation of heat resistance, ISOT oxidation tests (JIS K 2514) were performed on both the

PEC99/A and B series of oil sample under the following conditions.

Test conditions: 165.5°C, 72 hr

Evaluation standards: Rate of increase in viscosity, increase in total acid number,

non-dissolvable component, residual RBOT life

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1.3.4 Evaluation research on Lubricity

For both the PEC99/A and B series of oil sample, lubricity was evaluated by performing the

following tests.

*Shell wear test (ASTM D 4172): 75°C, 1200 rpm, 392 N, 60 min

*Shell EP test (ASTM D 2783): 1800 rpm

*Falex seizure test (ASTM D 3233): 290 rpm

*Falex wear test (ASTM D 2670): 290 rpm, 1334 N, 60 min, @80°C

*Pendulum test: @50°C, JASO method

1.3.5 Evaluation research on torque transmission force (friction coefficient)

With a 3-ball on disk tester, friction coefficient was measured under the following conditions

after changing oil temperature, load and rotary speed.

Test conditions

Oil temperature: 50°C, 100°C

Load: 50, 100, 150 N (Total load of 3 balls)

Rpm: 1, 5, 10, 20, 30, 50, 70, 100, 150, 200, 300 rpm

1.3.6 Research on additive synthesis

In 1998, compound-containing boron was synthesized in the laboratory, and it was confirmed

(by Falex test) that seizure resistance is improved by adding a small amount of the compound

(boron content: 100 ppm), but the problem of dissolvability in lubricant base oil remained. In

the current fiscal year, a boron compound of improved dissolvability was synthesized.

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2. R&D Results and Analysis Thereof

2.1 Properties and performances of sample oils

The properties of the sample oil used in fatigue tests and in torque transmission force tests are

presented in Table 2.2-1. The types of additives selected for the purpose of collecting

fundamental data on friction characteristic and heat resistance are entered under each item.

Table 2.2-1 Properties of Sample Oil

Fundamental system B series B series B series B series B series B series B series B series B series

Name of additive Commercial

ATF

Potassium

borate

Phosphoric

acid ester

amine salt

Hydrogen

phosphate

Viscosity (mm2/s)

Viscosity index

Total acid number (ngKOH/g)

Base number (mgKOH/g)

Aniline point

Metal quantity

Sulfur component

N component

Pendulum

Falex A method

Shell 4-ball

Shell wear

B base oil SP system-1 ZnDTP SP system-2 Ashless

carbamate

2.2 Results of rolling fatigue test

Taking the B series as the base system, rolling fatigue life was investigated primarily in

association with potassium borate and ZnDTP, which were recognized as prolonging fatigue life

in the PEC98/A series. Selected as the reference oil was ATF on the market (PEC99-03).

The results are shown in Table 2.2-2. In a comparison of standard oil SP and commercial ATF,

it was confirmed that potassium borate and ZnDTP could prolong rolling fatigue life. With

potassium borate, in particular, a prolonged fatigue life worthy of special note was exhibited in

the B series system with belt CVT considered.

Table 2.2-2 Rolling fatigue life of each oil sample

B series A series

L10 life L50 life L10 life L50 life

Base oil 0.5×106 15.6×10

6 1.0×10

6 3.7×10

6

SP 0.2×106 5.0×10

6 1.1×10

6 5.8×10

6

Potassium borate 7.0×106 46.2×10

6 6.5×10

6 14.2×10

6

DnDTP 0.6×106 7.7×10

6 0.1×10

6 15.1×10

6

Commercial ATF 0.1×106 5.7×10

6 －－

5

In addition, post-test rolling contact surface underwent analysis by EPMA. As a result, Ca, P

and O were detected in SP; Zn, S, P and O were detected in ZnDTP, and K, S, Ca, O and trace

amounts of boron were detected in potassium borate.

These results are compiled by L50 life in which A series and B series were compared and

presented in Figure 2.2-1.

Commercial

ATF

ZnDTP

Potassium

borate

SP

Base oil

A series

B series

Contact frequency (×106)

Figure 2.2-1 Impact of each additive on fatigue life

2.3 Results of heat resistance evaluation tests

With respect to 11 types of amine system additive and phenol system, in which improved

stability can be expected by adding oxidation inhibitor, additions were made to the A series

system and ISOT tests were performed. Moreover, in the post-test samples, remaining RBOT

life was investigated. The results are given in Table 2.2-3. Additive amounts were adjusted

so that the molality of each additive is equivalent (amine system: N = 300 ppm; phenol system:

equivalent mole amount).

The rate of increase in post-test viscosity (@40°C), total increase in acid number and residual

RBOT life were compiled and presented in Figures 2.2-2 to 2.2-4. Within the range of the

latest tests, the phenol system and naphthylamine exhibited favorable results; naphthylamine, in

particular, was favorable.

Table 2.2-3 Oxidation inhibitor performance

Name of additiveViscosity increase rate (%) Increase in total

acid number (mgKOH/g)

Residual RBOT life (min)

Non-dissolvable component

A method (wt %)

Cu dissolution volume (ppm)

Phenol system

Bisphenol

Bissulfide

Terphenol

(Amine system)

Diphenylamine - 1

Diphenylamine - 2

Diphenylamine - 3

Naphthylamine

Aromatic amine - 1

Aromatic amine - 2

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Aromatic amine-2 (0.65 wt%)


Naphthylamine (0.47 wt%)

Diphenylamine-3 (0.90 wt%)



Terphenol (1.14 wt%)

Bissulfide (1.01 wt%)

Bisphenol (0.45 wt%)

Rate of increase in viscosity (%)

DBEP (0.50 wt%)

DBPC (0.47 wt%)

Figure 2.2-2 Rate of increase in post-experiment viscosity (@40°C)










Increase in total acid number (mgKOH/g)

DBEP (0.50 wt%)

DBPC (0.47 wt%)

Figure 2.2-3 Rate of increase in post-experiment total acid number


Residual RBOT life (min)









DBEP (0.50 wt%)

DBPC (0.47 wt%)

3355 hr

Figure 2.2-4 Residual RBOT life after completion of experiments

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2.4 Results of lubrication evaluation tests

For the purpose of collecting fundamental data for improving lubrication, 18 types of oil agent

and EP agent were selected, and the friction and wear characteristics of sample oil added to the

A series and B series each were investigated. In each case the additive amount was 1% and

the results are given in Table 2.2-4.

The additives which exhibited favorable performance in each friction test are as summarized

below.

*Pendulum test (µ)

The addition of acidic phosphoric ester (amine salt) lowered µ. Generally speaking, µ was

higher in the B series than in the A series system.

For cases in which µ exceeded 0.3 in the A series, it is believed that seizure was produced on

friction surfaces. With the additives belonging to this group, µ in the B series became low.

*Falex test (Wear: 80°C, 1334 N, 290 rpm, 60 min)

Phosphoric acid ester exhibited favorable performance. There were no major differences in

Falex wear amount between the A and B series.

*Falex test (Seizure: A method, 290 rpm, 80°C)

Phosphoric acid ester and sulfur type additives exhibited favorable performance. There were

no clear differences between the A and B series, but with acidic phosphoric ester, the seizure

load tended to decline in the B series.

*Shell wear test (75°C, 392 N, 1200 rpm, 60 min)

Acidic phosphoric acid ester was favorable in the A series, as were the sulfur type and organic

metal type (Zn, Mo) additives in the B series.

*Shell EP test

LNL: Organic metal type and sulfur type additives were favorable. Acidic phosphoric ester was

good in the A series, but performance dropped in the B series.

WL: Sulfur type additives exhibited favorable performance.

LWI: ZnDTP and sulfur type additives were favorable. Acidic phosphoric ester was good in the

A series, but performance dropped in the B series.

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2.5 Results of torque transmission force evaluation tests

Using a ball-on-disk tester (3-ball-on-disk format), the friction force (torque transmission force)

of each PEC99 sample oil was measured under conditions of changed load and sliding speed,

and friction coefficients were compiled. An example of measurement results for PEC99-05

(ZnDTP) is shown in Figure 2.2-5.

Rpm

Fri

ctio

n c

oe

ffic

ien

t (µ

)

Rpm F

rictio

n c

oe

ffic

ien

t (µ

)

(Experiment oil temperature: 50°C) (Experiment oil temperature: 100°C)

Figure 2.2-5 Examples of friction coefficient measurement results

Figure 2.2-6 presents a compilation of friction coefficients, at 50°C and 100°C oil temperatures,

with each sample oil load weight at 10 kgf, and µ100 taken as the friction coefficient at 100 rpm

and µ10 taken as the friction coefficient at 10 rpm.

B + carbamate

B + ZnDTP

B + potassium

Commercial ATF

B +SP

B series base oil

P150 base oil

B + carbamate

B + ZnDTP

B + potassium

Commercial ATF

B +SP

B series base oil

P150 base oil

(Experiment oil

temperature: 50°C)

(Experiment oil

temperature: 100°C)

Figure 2.2-6 Friction coefficient measurement results

In a comparison of µ100 and µ10, we find that the friction coefficient becomes small at µ100;

and in nearly all oil samples, when rpm increased, the coefficient tended to become small (with

commercial ATF, µ dropped at ultra-low rpm). Moreover, µ was larger at 100°C than at 50°C.

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When attention is focused on µ (µ100) at an oil temperature of 100°C, which is believed to be

close to the oil temperature during actual CVT operation, ZnDTP and potassium borate manifest

high friction coefficients. It is conjectured that adding these additives will make it possible to

create a final trial-produced oil that has a high transmission torque capacity.

2.6 Research on synthesis of additives

Continuing from the year 1998, attempts were made to synthesize new compounds containing

boron. In compound synthesized in 1998, it was confirmed that Falex seizure load is improved

by small amounts of additive, but there was the drawback that dissolvability in lubricant base oil

becomes inferior. Accordingly, two types of compound with improved dissolvability were

synthesized in the current fiscal year.

Table 2.2-5 gives the properties and the friction/wear characteristics of synthesized compounds

when they have been added at 1 wt% each to base oil (PEC99/A and B series).

Table 2.2-5 Performance of synthesized compounds

Fundamental system A series A series B series

Viscosity (mm2/s)

Viscosity index

Total acid number (ngKOH/g)

Base number (mgKOH/)

Aniline point (°C)

Metal quantity (ppm)

Sulfur component (%)

N component (%)

Pendulum (80°C, JASO)

Falex (A method)

Shell 4-ball (1800rpm)

Shell wear (1200rpm)

Synthesizedcompound A

Name of additive Synthesizedcompound B

Synthesizedcompound B

In terms of friction/wear characteristics, the compounds recently synthesized cannot be

described as being distinctive. With 1 wt% additives, however, the amount of boron in the

sample oil is low at 30 to 40 ppm, and it is believed that various issues remain to be investigated

including methods of producing the compound itself and purity.

10

3. R&D Results

3.1 Fatigue life and lubricant oil additive

(1) When rolling fatigue life results are compiled by L50 life, the addition of ZnDTP and

potassium borate act to prolong fatigue life and a long fatigue life was demonstrated in

contrast to SP type additive or commercial ATF, which were used for comparison. A

long fatigue life worthy of note was demonstrated especially by oil with potassium borate

added.

(2) As a result of post-test rolling contact surface analysis by EPMA, Zn, S, P and O were

detected in ZnDTP-added oil, and K, S, Ca, O and trace amounts of boron were detected

in potassium borate. It is believed that these elements and/or their reactive byproducts

acted effectively to prolong fatigue life.

3.2 Heat resistance and lubricant oil additive

(1) In sample oil to which phenol type compound (e.g., DBPC) has been added, the change

in viscosity before or after completion of ISOT test and the overall increase in acid number

were slight, and the production of non-dissolvable component could be curtailed.

(2) Of the sample oils to which amine type compound has been added, there were many in

which viscosity or overall increase in acid number was large in comparison to phenol type

compound, but only naphthylamine exhibited a dramatic improvement in stability.

3.3 Friction/wear characteristics and lubricant oil additive

Each type of oil agent and extreme pressure agent was selected; the compounds of each were

added to the A series and B series, and friction/wear characteristics were investigated. The

results are summarized below.

(1) Pendulum test (µ)

The addition of acidic phosphoric ester (amine salt) or sulfurized oil lowered µ. Generally

speaking, µ was higher in the B series than in the A series system.

(2) Falex test (Wear: 80°C, 1334N, 290 rpm, 60 min)

Phosphoric ester exhibited favorable performance. There were no major differences in

Falex wear between the A and B series.

(3) Falex test (Seizure: A method, 290 rpm, 80°C)

Acidic phosphoric ester (a mine salt) and sulfur type additives exhibited favorable

performance. There were no clear differences between the A and B series, but with

acidic phosphoric ester, the seizure load tended to decline in the B series.

(4) Shell wear test (75°C, 392N, 1200 rpm, 60 min)

Acidic phosphoric ester was favorable in the A series, as were the sulfur type and organic

metal type (Zn, Mo) additives in the B series.

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(5) Shell EP test

LNL: Organic metal type (Zn, Mo) and sulfur type additives were favorable. Acidic

phosphoric ester was good in the A series, but performance dropped in the B series.

WL: Sulfur type additives exhibited favorable performance.

LWI: ZnDTP and sulfur type additives exhibited favorable performances. Acidic

phosphoric ester performed well in the A series, but its performance dropped in the

B series.

3.4 Torque transmission force and lubricant oil additive

Using a ball-on-disk tester (3-ball-on-disk format), the friction coefficients of each PEC99

sample oil were measured under conditions of changed load, sliding speed and oil temperature.

Friction coefficients were largely affected by oil temperature and sliding speed but the impact of

load was relatively small. When attention is focused on µ at an oil temperature of 100°C,

which is believed to be close to the oil temperature during actual CVT operation, oils with

ZnDTP and potassium borate added manifest high friction coefficients. It is conjectured that

adding these additives will make it possible to create a final trial-produced oil that has a high

transmission torque capacity.

3.5 New compound synthesis and performance evaluation

Attempts were made to synthesize new compounds containing boron. In compound

synthesized in 1998, a unique effect was confirmed in the improvement of Falex seizure load by

small amounts of additive, but there was the drawback that dissolvability in lubricant base oil

becomes inferior. Accordingly, two types of compound with improved dissolvability were

synthesized in the current fiscal year, and their performances were evaluated.

In both types of compound synthesized in the current fiscal year, dissolvability in lubricant oil

base was outstanding, but the compounds could not be described as distinctive in terms of

friction/wear characteristics. From analysis of sample oils, however, it was found that with 1

wt% additives the amount of boron in the sample oil is low at 30 to 40 ppm, and it is believed

that various issues remain to be investigated including methods of producing the compound

itself and purity.

Patent application was made jointly with PEC for claim item (lubricant oil additive with

nitrilo-tri-ethanol-borate as the main ingredient) with compound synthesized in 1998 included.

Patent application number: Tokugan 309220 - 1999

Patent application date: October 29, 1999

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4. Synopsis

(1) From research on the prolongation of fatigue life by lubricant oil, using a rolling fatigue life

tester, it was found that the addition of ZnDTP and potassium borate are effective.

Moreover, from surface analysis of the test piece roll surface after testing, the elements

included in the added compound could be detected, and it is suspected that these

elements or their reactants have an impact on fatigue life prolongation.

(2) In research on improvement of heat resistance, it was confirmed that the addition of

phenol compounds such as DBPC or naphthyla mine, etc., proves to be effective in

improvement of stability.

(3) The effects of each type of oil agent or extreme pressure agent on friction/wear

characteristics were confirmed in both the A and B series systems. Consequently,

fundamental data useful for compiling the specifications of the final candidate oil could be

gathered.

(4) Using a 3-ball-on-disk tester, friction coefficients were measured under different sets of

conditions in terms of load, sliding speed and oil temperature. It was found that when

attention is focused on friction coefficient at 100°C, oils with ZnDTP and potassium borate

added manifested high friction coefficients.

(5) In the synthesis of new compounds, an attempt was made to synthesize compound

containing boron, which is outstanding in dissolvability into lubricant oil base. These

results were compiled, together with research results in 1998, and application for patent

was made (Tokugan 309220-1999: application made jointly with PEC).

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Table 2.2-4 Friction/wear characteristics of PEC-99 sample oils

Pendulum µ Falex wear (mg) Falex Seizure (N) Shell wear (mm) Shell EP (A series) Shell EP (B series) Category

Additive content

A series B series A series B series A series B series A series B series LNL WL LWI LNL WL LWI

S system Polysulfide terpene

0.170 0.163 13.6 24.0 5095 4231 0.74 0.49 785 1569 322 785 1961 342

Polysulfide 0.178 0.166 20.3 29.1 3260 4093 0.80 0.56 490 2452 364 490 2452 319

Sulfurized oil 0.108 0.158 12.1 10.9 5425 3492 0.53 0.50 618 1569 274 490 1961 238

SP SP package 0.125 0.154 12.8 14.8 4873 3042 0.52 0.43 490 1569 237 490 1961 248

P system Phosphoric acid ester a mine salt

0.101 0.147 2.7 1.7 7076 2690 0.49 0.59 618 1569 304 98 1236 74

Acid phosphate amine salt

0.331 0.184 6.8 5.1 3020 2851 0.80 0.75 785 1236 311 490 1569 218

Dioleyl acid phosphate

0.083 0.139 1.4 1.4 5153 6245 0.41 0.78 981 1236 382 618 1569 264

TCP 0.153 0.158 5.0 3.4 3330 2220 0.88 0.57 490 1236 205 490 1236 207

Metal systems

ZnDTP 0.156 0.143 20.3 11.5 3763 4766 0.79 0.43 981 1961 401 981 1569 391

Borate -1 0.156 0.161 9.1 6.1 2980 2570 0.66 0.77 314 981 138 314 1236 145

Borate -2 0.147 0.138 15.1 10.1 2071 2521 0.83 0.64 196 981 101 392 1236 174

Mo DTC 0.320 0.165 4.5 2.3 2962 2810 0.66 0.48 618 1569 266 618 1236 253

ZnDTP, Ca sulfonate

0.230 0.153 16.6 21.2 3180 3862 0.81 0.45 785 1236 315 785 1569 323

Washing agent

Ca sulfonate (85TBN)

0.316 0.147 Seizure 9.3 1831 1951 0.85 0.60 392 1569 178 392 1236 173

Ca salicylate 0.234 0.154 7.9 9.6 2240 2120 0.53 0.73 314 981 136 98 1236 70

Ca sulfonate (285TBN)

0.385 0.159 Seizure 15.9 2730 2280 0.74 0.52 392 1569 178 392 1236 175

Other Fatty acid amide

0.125 0.131 13.4 7.4 1969 2200 0.69 0.51 314 981 135 235 1236 121

Lecithin 0.115 0.140 9.9 8.4 3100 2383 0.67 0.59 98 1569 86 98 1569 89

Base oil A, B base oil Seizure 0.150 Seizure 13.7 1640 2100 0.75 0.65 78 981 53 98 1236 68

A series: P150 + each additive (1%)

B series: P150 + Ca sulfonate + dispersant + each additive (1%)

Pendulum: 50°C, JASO method

Falex wear: 80°C, 1334 N, 60 min

Shell wear: 75°C, 392 N, 60 min

Falex seizure: A method, 290 rpm, 80°C, run in 1110 N, 5 min

Copyright 2000 Petroleum Energy Center all rights reserved.

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