O-tolidine Diisocyanate (TODI)

Product Description

Urethane elastomer have various advantages when compared with rubber, plastic and metal. This is especially true of the urethane elastomers made using Tolidine diisocyanate (TODI). TODI-based elaastomers offer excellent heat resistance and hydrolysis resistance properties along with superior mechanical properties.

From the manufacturing stand point, TODI based prepolymer can be stored for certain period, and TODI, because of its longer pot life, is easlier to handle than NDI-based products.

Application of TODI urethane elastomer

Because of its unique properties of heat resistance and hydrolysis resistence, TODI urethane elastomers can be used in various areas including:

1) Sealing (oil sealing, piston ring, water sealed, etc.)
2) Automobile parts (grille, shock absorbers, bumoer extensions, roof, door, window and body, etc.)
3) Industrial use (belt, roll, caster, etc.)
4) Electric (coating agent, etc.)
5) Medical equipment (artificial organ, etc.)

What is TODI ?

Name T.O.D.I., R203 (CAS No. 91-97-4)
4.4'-Diisocyanato-3.3'-dimethyl-1.1'-biphenyl
  or   3.3'-Dimethyl-4.4'-biphenyldiisocyanate
  or   O-Tolidine diisocyanate
Chemical Structure
Purity Min. 99.5 %
Molecular weight 264.286
Package 40 kg Fiber drum with inner plastic bag
Storage Keep cool and dry place

Technical Information
Physical and Chemical Properties
1. Appearance White pellets
2. Odor Odorless
3. Boiling Point 195-197°C (5mmHg, or 667 Pa)
4. Melting Point 71.7°C
5. Specific Gravity 1.197 (80°C)
6. Solubility Insoluble in water and slowly hydrolyzed by water. Soluble in aceton, carbon tetrachroride, kerosene, benzene, chlorobenzene, nitrobenzene
7. Flash point 218°C (cleveland open cup)

Procedure of Making TODI urethane elastomer
There are various combinations of materials, blending ratios and manufacturing methods for achieving appropriate properties in TODI based urethane elastomer. The following is just one example of making a TODI urethane elastomer using the pre polymer method.

1) Materials  
Isocyanate TODI
Polyester Ethylene glycol
Or Condensation product of Adipic acid and blended glycol,
Or Ring-opening polymerization polyester of Caprolactone
(M.W.; around 2,000, OH Value; about 56, AV<1 Acid Value)
Cross-Linking agent 1.4 Butanediol
Catalyst Triethlenediamine (DABCD, Houdry Process Corp.)
Stannous Octoate (T-9, T&M)

Example 1. ODX-105(OH Value = 54.5)
R NCO Index Polyester TODI
1.4 Butanediol
2.0 1.1 100 25.7 3.6
2.6 1.2 100 33.3 5.1
3.0 1.1 100 38.5 7.6

Example 2. Caprolactone (OH Value = 55.1)
R NCO Index Polyester TODI
1.4 Butanediol
2.0 1.2 100 25.9 2.9
2.6 1.2 100 33.7 5.2
3.8 1.1 100 49.3 10.9

3) Manufacturing Process (Pre-Polymer Method)

Making pre-polymer

Dehydrated polymer under reduced pressure (110-112°C, 1-2 mmHg, for 2 hours) is poured in separable flask with stirrer and desiccators and place in the oil bath held at 100°C. After the temperature of polyester reaching 100°C, TODI is added into this flask. Although the reaction of TODI and polyester is exothermic reaction, the increment of temperature stops within a few minutes. So, cooling in not needed. The addition reaction of TODI is finished when -OH of polyester is consumed by the same molar amount of -NCO. (Reaction time for ODX-105 is 2 hours, and for caprolactone is 2.5-3 hours at 100°C, Fig.1). Viacosity change during this addition reaction is shown at Figure 2.

Fig. 1. Relationship between reaction % and time in pre-polymer.
M-103ES = Caprolactone polyester, ODX-105 = Condensation product of blended glycol and adipic acid. R = -NCO/OH, Temperature of reaction is 100°C
Fig. 2. Relationship between reaction % and Viscosity of pre-polymer.
M-103ES = Caprolactibe polyester, R = -NCO/OH, Temperature of reaction is 100°C

Addition of cross linking agent (1.4 Butanediol) and catalysis

200 g of pre-polymer is taken into 1 liter beaker, and heat to 110°C on the electric heater. Dehydrated 1.4 Butanediol under the reduced pressure is added into heated pre-polymer and stirred well. Temperature of pre-polymer should not be over 115°C. Addition of 1.4 Butanediol before the complete reaction of TODI and polyester does not change the final physical properties of TODI urethane elastomer. The time from the addition of 1.4 Butanediol until gelation (Pot Life) is depends on the blended ratio. But addition of catalysis can shorten the Pot Life and 2nd aging period. The physical properties of final product are not changed. Generally DABCO Triethylendiamine) and T-9 (Stannous octoate) are used as a catalyst for this reaction.

Table 1
Effect of Catalysis amount on the physical properties of TODI based urethane elastomer
Polyester
R
NCO Index
Reaction time of
Pre-polymer
Caprolactone
3.8
1.1
1.0
Catalysis
Pot Life (seconds)
0
270
0.3
100
0.5
60
1st aging (Hours) 48 48 48 48
2nd aging (Days) 10 50 10 10
Tensile strength (Kg/cm2) 273 360 363 379
Tearing strength (Kg/cm2) 117 139 142 143
100% Modulus (Kg/cm2) 112 114 111 114
Elongation (%) 600 580 600 620
Hardness (Shore A) 95 95 95 95

De-gassing (Reduce pressure to 1-2 mmHg, within pot life)

Immediately after the1.4 Butanediol is added and stirred, the beaker is placed in a desiccator and is de-gassing under the reduced pressure (1-2 mmHg).

Molding

Generally metal molds (separate type) is used for molding. Each piece of mold can be fixed with screw, and 3 mm spacer can be inserted between each piece of mold. Each mold is coated by Silicone DC-20 (Dow Corning) or Silicone KS-61, and heated around 110°C. Material is gently poured into both molds without making any foam, and attached together and fixed with a screw.

Detaching the Mold

The mold is placed in the oven and held at 110°C for 1-2 hours. The time for molding depends on the blended ratio. At the time of de-molding, the cross linking reaction is not completed yet, so the urethane elastomer should be handled carefully.

1st aging at 110°C for 24-48 hours

After demolding, the urethane elastomer is placed in an aging oven held at 110°C for 24-48 hours. The aging time depends on the kinds of polyester or blending ratio, but 48 hours is enough for all formulation.

Table 2
The effect of 1st aging time on the physical properties of TODI based urethane elastomer
Polyester
R
NCO Index
Reaction time of
Pre-polymer
Catalysis
Caprolactone based
3.8
1.1
1.0
0.3
1st aging (Hours) 24 48 72
2nd aging (Days) 10 10 10
Tensile strength (Kg/cm2) 298 363 375
Tearing strength (Kg/cm2) 131 142 142
100% Modulus (Kg/cm2) 109 111 114
Elongation (%) 560 600 600
Hardness (ShoreA) 95 95 95

2nd aging for 10 days

After finishing 1st aging, urethane elastomer is placed at room temperature (>25°C) for 7-10 days. It should have final physical properties.

Table 3
The effect of 2nd aging time on the physical properties of TODI based urethane elastomer
Polyester
R
NCO Index
Reaction time of
Pre-polymer
Catalysis
Caprolactone based
3.8
1.1
1.0
0.3
1st aging (Hours) 48 48 48 48
2nd aging (Days) 4 6 10 40
Tensile strength (Kg/cm2) 337 357 363 369
Tearing strength (Kg/cm2) 137 139 142 141
100% Modulus (Kg/cm2) 104 102 111 110
Elongation (%) 580 600 600 610
Hardness (ShoreA) 95 95 95 95

The physical properties of TODI urethane elastomer

The physical properties of TODI urethane elastomer (Example 1 and 2) were measured by the analysis method of JIS-K-6301.

Table 4
Comparison of physical properties among various urethane elastomers
Isocyanate TODI NDI
Polyester ODX-105 Caprolactone based ODX-105
Polyester
Diisocyanate
1.4 Butanediol
Catalysis
100
25.7
3.6
No

100
33.3
5.1
No
100
38.5
7.6
No
100
25.9
2.9
No
100
33.7
5.2
No
100
49.3
10.9
DABCO*1
100
25
5
N.A.
100
18
2
NA
R
NCO Index
2.0
1.1
2.6
1.2
3.0
1.1
2.0
1.2
2.6
1.2
3.8
1.1
2.5
1.1
1.8
1.2
Pre-polymer
Reaction time (Hrs)
2
2 2 2 2 1 0.07 0.07
Pot Life (Sec) 1120
300 160 2700 720 95 25 130
1st aging at 110°C (Hrs) 24
24 24 24 48 48 24 24
2nd aging (Days) 10
10 10 10 10 10 10 10
Tensile strength (Kg/cm2) 285
305 320 285 348 380 234 394
Tearing strength (Kg/cm2) 65
97 103 68 88 145 131 104
100% Modulus (Kg/cm2) 36
61 77 30 62 110 85 53
Elongation (%) 900
820 760 660 590 560 720 800
Hardness (ShoreA) 81 88 93 80 88 95 92 83
*1 0.3% DABCO (triethylenediamine)

The heat resistance and hydrolysis resistance of TODI based urethane elastomer

The polyurethane elastomer based on TODI and Caprolactone Polyester has superior heat resistance and hydrolysis resistance properties than the polyurethane elastomer based on NDI polyester (Fig. 3 and Fig. 4)

Fig. 3 Effect of high temperature aging on the physical properties of three kinds of urethane elastomers (Heat Resistance)
Change ratio = f /f0, f0: Initial value, f: Value after the storage in 120°C
TODI-M-103ES (R=3.8, NCO Index=1.1)
TODI-M-103ES (R=3.8, NCO Index=1.1)
NDI-ODX-105 (R=2.6, NCO Index=1.2)
Fig. 4 Effect of high temperature and high humidity on the physical properties of three kinds of urethane elastomer (hydrolysis resistance)
Change ratio = f / f0, f0: Initial value, f: Value after the storage in 100°C and 100% humidity.
TODI-M-103ES (R=3.8, NCO Index=1.1),
TODI-M-103ES (R=3.8, NCO Index=1.1),
NDI-ODX-105 (R=2.6, NCO Index=1.2)

Comparison of the Characteristics of Urethane elastomer by different Polyol, isocyanate and cross-linking agent.

Materials for urethane elastomer are Polyol, Diisocyanate and Cross-linking agent, and the physical and chemical characteristics of the urethane elastomer are determined by the combination of these materials. Theoretically there are many of the combinations of these materials for making urethane elastomer, however, many of the combinations are failed to make in the practical situation. The following tables are showing the basic trend of the characteristics of urethane elastomer made by various materials.

Polyol
Polyol is a relatively large molecule weight material for the urethane elastomer (1000-2500), and is called soft segment because of its long shape. Polyol is mainly divided into two groups, one is Polyether-Polyol and the other is Polyester-Polyol. About 90% of the Polyol used in urethane elastomer is Polyester-Polyol (85% is Polypropylene Glycol), and the other 10% is Polyester-Polyol.

Table 7-1
The influence of Polyol on the characteristics of urethane elastomer
  Characteristics of Urethane elastomer
Influence Big < ------------------------------------------ > Small
Type of Polyol Water Resistance Oil Resistance Chemical Resistance Cold Resistance
Ethyleneglycol Adipic Ester (C2) D C B D
Ethylenbutanediol Adipic Ester(C2,C4) C C C C
Butanediol Adipic Ester (C4) B C C B
Propyleneglycol Ether (C3) C D D C
Tetra-Methylen Glycol Ether (C4) A C B A
Caprolactone Ester (C5) B A B C
3 Methyl-1.5pentan Adipic Ester B C C A
Hexadiol Adipic Ester (C6) B B B D
Carbonate Ester (C6) A A A D
A: Excellent, B: Good; C: Fair; D: Inferior

  Characteristics of Urethane elastomer
Influence Big < ------------------------------------------ > Small
Type of Polyol Heat Resistance Hardness Flexural Strength Permanent Deformation Climate Resistance
Ethyleneglycol Adipic Ester (C2) C A A A C
Ethylenbutanediol Adipic Ester(C2,C4) C C C C C
Butanediol Adipic Ester (C4) C C B C B
Propyleneglycol Ether (C3) D C C D C
Tetra-Methylen Glycol Ether (C4) C C B C A
Caprolactone Ester (C5) B B C C B
3 Methyl-1.5pentan Adipic Ester C C A C B
Hexadiol Adipic Ester (C6) B C C C C
Carbonate Ester (C6) B B C C A
A: Excellent, B: Good; C: Fair; D: Inferior

Diisocyanate is the small molecule weight material (150-300) and is called hard segment. It forms the bone of Urethane elastomer and influences the hardness, physical characteristics and heat resistance characteristics of the urethane elastomer.

Table 7-2
The influence of Diisocyanate on the characteristics of urethane elastomer
  Characteristics of Urethane elastomer
Influence to Urethane elastomer Big < ------------------------------------------ > Small
Type of diisocyanate Hardness Heat Resistance Elastic Modulus Abrasion Resistance
TDI (Tolylene diisocyanate) C C B C
MDI (Diphenylmethane diisocyanate) B C C C
NDI (Naphthalene diisocyanate) A B B B
TODI (Oltho-Tolidine diisocyanate) B A C A
PPDI (Para-phenylene diisocyanate) A A A B
A: Excellent, B: Good; C: Fair; D: Inferior

  Characteristics of Urethane elastomer
Influence to Urethane elastomer Big < ------------------------------------------ > Small
Type of diisocyanate Light Resistance Flexural Strength Temperature Dependability Chemical Resistance
TDI (Tolylene diisocyanate) C C C C
MDI (Diphenylmethane diisocyanate) C B C C
NDI (Naphthalene diisocyanate) D B A B
TODI (Oltho-Tolidine diisocyanate) C C B B
PPDI (Para-phenylene diisocyanate) B A A B
A: Excellent, B: Good; C: Fair; D: Inferior

Cross-linking agent

Cross linking agent is less influential material for the characteristics of urethane elastomer, and its molecule weight is small (60-200). There are four types of cross-linking agents for urethane elastomer, which are water, diol type, triol type and diamine type.

Table 7- 3
The influence of Cross-linking agent on the characteristics of urethane elastomer
  Characteristics of Urethane elastomer
Influence to Urethane elastomer Big < ------------------------------------------ > Small
Type of Cross linking agent Heat Resistance Water Resistance Hardness Permanent Deformation
Water (H2O) B B A A
Ethyleneglycol (EG) B D B B
1.4 Butanediol (1.4 BD) C B B C
Trimethylolepropane (TMP) B B C A
Methylene bis oltho chlolaniline (MOCA) A A B B
Bishydroxyethyletherbenzen (BHEB) B A C B
A: Excellent, B: Good; C: Fair; D: Inferior

  Characteristics of Urethane elastomer
Influence to Urethane elastomer Big < ------------------------------------------ > Small
Type of Cross linking agent Flexural Strength Cold Resistance Abrasion Resistance
Water (H2O) B A A
Ethyleneglycol (EG) B C B
1.4 Butanediol (1.4 BD) B B C
Trimethylolepropane (TMP) D D C
Methylene bis oltho chlolaniline (MOCA) C D B
Bishydroxyethyletherbenzen (BHEB) D D C
A: Excellent, B: Good; C: Fair; D: Inferior