Processing Aids for Viton

Transcription

1 Technical Information Processing Aids for Viton Introduction VPA No. 1 is a general-purpose processing aid useful in all types of molded goods made from Viton. It provides smooth preforms, slightly faster cure rates, and excellent mill and mold release characteristics. It has little or no effect on vulcanizate properties. VPA No. 2 is a particularly effective extrusion aid allowing compounds of Viton to extrude faster, cooler, and smoother. It has some adverse effect on high-temperature compression set. VPA No. 3 provides the best mold release. lt has little or no effect on standard physical properties, including compression set resistance, and increases the cure rate of bisphenol-cured systems. VPA No. 3 is best suited for molding operations with automatic part removal and tight compression set resistance requirements. Applications The VPA processing aids are recommended for use in Viton for the following applications: O-rings, seals, molded shapes, diaphragms, and tubing. The comparative advantages of this family of processing aids in different operations are shown in Table 1. Use of VPA Processing Aids Typical processing and vulcanizate properties in compounds of Viton are shown in Table 2 (VPA No. 1), Table 3 (VPA No. 2), Table 4A and 4B (VPA No. 3). Product Descriptions VPA No. 1 VPA No. 2 VPA No. 3 Physical Form Powder Flakes Pellets Color Light tan to Yellow Tan to white light brown Composition Wax/ Vegetable 75% sulfur aromatic wax compound sulfur on compound inert carrier Specific Gravity Melting Point, C ( F) 150 (302) 80 (176) Recommended Level, phr Handling Precautions VPA No. 1 and VPA No. 3 can cause eye and skin irritation. Avoid contact with eyes, skin, and clothing and avoid breathing dust. Use with adequate ventilation and wash thoroughly after handling. In case of eye contact, immediately flush eyes with plenty of water for at least 15 min and call a physician. VPA No. 2 has no known toxicological hazards. Keep all containers closed to avoid contamination. Store in a cool, dry place. Before compounding or processing Viton fluoroelastomers, read DuPont Dow Elastomers technical bulletin H , Handling Precautions for Viton. Table 1 Comparison of Process Aids in Viton Mold Mill Calender Extrusion Compression Set Release Release Smoothness Resistance VPA No. 1 o/+ + o/+ o/ VPA No VPA No o o o ++ very positive effect o no effect + positive effect negative effect

2 Product Descriptions VPA No. 1 VPA No. 1 is recommended for all types of molded goods made from Viton. It is an effective mill release agent and is particularly useful on mills with inadequate cooling facilities. It can be premixed with the other compounding ingredients and added to the batch. It has little or no effect on processing safety but has a slight activating effect on cure rate at 177 C (350 F). Rod-type preforms from compounds containing VPA No. 1 are smooth and uniform. Note: Complicated extrusion profiles from compounds containing VPA No. 1 are not quite as smooth as those obtained with VPA No. 2. A slight bloom will be noted on preforms and presscured articles containing VPA No. 1, which disappears during the oven post-cure. VPA No. 1 has no effect on original or heat-aged stress/strain properties and only a minor effect on high-temperature compression set. Two parts of VPA No. 1 in a standard formulation with Viton E-60C will increase shrinkage approximately 0.4% after an oven post-cure of 24 hr at 232 C (448 F). VPA No. 2 has little or no effect on processing safety, cure rate, or stress/strain properties. It does have an adverse effect on high-temperature compression set. Also, 2 phr of VPA No. 2 in a standard formulation with Viton E-60C will increase shrinkage approximately 0.4% after an oven post-cure of 24 hr at 232 C (448 F). VPA No. 3 VPA No. 3 is recommended for all types of molded goods of Viton. It can be premixed with other compounding ingredients and added as usual. It increases cure rate and can affect scorch safety with bisphenolcured compounds. VPA No. 3 is hygroscopic a loss of compound scorch safety can occur if exposed to water, including high-humidity conditions. VPA No. 3 does not affect peroxide-cured compound cure rate. VPA No. 3 has no effect on original or heat-aged stress/strain properties, including compression set resistance. Addition of 1.6 phr to Viton E-60 increases shrinkage by 0.3%; 2 phr added to Viton GF increases shrinkage by 0.5%. Both after an oven post-cure of 24 hr at 232 C (448 F). VPA No. 2 VPA No. 2 is recommended as an extrusion aid for a variety of extruded goods such as tubing and complex profiles. It can be premixed with other compounding ingredients and added to the batch. As with all waxtype processing aids, proper extruder temperatures are very important. A cool screw and barrel in the feed section of the extruder are particularly important to prevent stock slippage on the screw (see Table 3 for suggested conditions). Extrudates containing VPA No. 2 are generally smooth and glossy. 2

3 Table 2 VPA No. 1 Processing Aid in Viton E-60C and Viton E-430 Compound 2A 2B 2C 2D 2E Viton E-60C Viton E MT Carbon Black High-activity MgO Calcium Hydroxide VPA No Mooney Scorch, MS at 121 C (250 F) Units, minimum Time to 5-pt rise, min 1 pt in 2 pt in 3 pt in 0 pt in 0 pt in 45 min 45 min 45 min 45 min 45 min ODR at 177 C (350 F), Microdie, 1 Arc M L, N m (in Ib) 0.8 (6.8) 0.7 (6.5) 0.7 (6.3) 0.5 (4.7) 0.4 (3.9) t s 0.23 (t s 2), min t c 90, min M H, N m (in Ib) 5.5 (49) 5.6 (50) 5.4 (48) 3.4 (30) 3.2 (28) Garvey Die Extrusion (cold feed, cold screw, barrel extension 24 C, barrel 66 C, head 104 C, die 135 C, screw speed 35 RPM) Rate, cm/min Die swell, g/cm Stock temperature, C ( F) 124 (255) 124 (255) 121 (250) 113 (235) 110 (230) Appearance (Ratings range from 1 = very smooth to 4 = very rough) Back Edge Surface Feather Edge After press cure After oven cure % Modulus, MPa (psi) 5.9 (850) 6.4 (925) 5.7 (825) 1.6 (225) 1.6 (225) Tensile Strength, MPa (psi) 13.1 (1,900) 13.3 (1,925) 12.9 (1,875) 11.7 (1,700) 12.2 (1,775) Elongation at Break, % Hardness, durometer A Stress/Strain at 23 C (73 F) After Aging 70 hr at 275 C (528 F) 100% Modulus, MPa (psi) 5.0 (725) 5.0 (725) 4.5 (650) 1.7 (250) 1.7 (250) Tensile Strength, MPa (psi) 11.4 (1,650) 11.5 (1,675) 11.0 (1,600) 9.8 (1,425) 10.9 (1,575) Elongation at Break, % Hardness, durometer A mm x 4.0 mm 70 hr at 24 C (75 F) hr at 200 C (392 F) hr at 200 C (392 F) hr at 232 C (450 F)

4 Table 3 VPA No. 2 Processing Aid in Viton E-60C and Viton B-910 Compound 3A 3B 3C 3D 3E 3F Viton E-60C Viton E MT Carbon Black High-activity MgO Calcium Hydroxide VPA No Mooney Scorch, MS at 121 C (250 F) Units, minimum Time to 5-pt rise, min 1 pt in 2 pt in 2 pt in min 45 min 45 min Time to 10-pt rise, min 42 9 pt in min ODR at 177 C (350 F), Microdie, 1 Arc M L, N m (in Ib) 0.8 (6.8) 0.8 (6.8) 0.8 (6.8) 1.2 (11) 1.2 (11) 1.2 (10.5) t s 0.23 (t s 2), min t c 90, min M H, N m (in Ib) 5.5 (49) 5.4 (48) 5.3 (47) 6.0 (53) 5.8 (52) 5.7 (51) Garvey Die Extrusion (cold feed, cold screw, barrel extension 24 C, barrel 66 C, head 104 C, die 135 C screw speed 35 RPM) Rate, cm/min Die swell, g/cm Stock temperature, C ( F) 124 (255) 113 (235) 110 (230) 127 (260) 124 (255) 118 (244) Appearance (Ratings range from 1 = very smooth to 4 = very rough) Back Edge Surface Feather Edge After press cure After oven cure % Modulus, MPa (psi) 5.9 (850) 6.9 (1,000) 7.1 (1,025) 5.7 (825) 5.9 (850) 6.2 (900) Tensile Strength, MPa (psi) 13.1 (1,900) 12.4 (1,800) 12.4 (1,800) 15.0 (2,175) 14.1 (2,050) 14.3 (2,075) Elongation at Break, % Hardness, durometer A Stress/Strain at 23 C (73 F) After Aging 70 hr at 275 C (528 F) 100% Modulus, MPa (psi) 5.0 (725) 5.7 (825) 6.9 (1,000) 2.4 (350) 2.8 (400) 3.3 (475) Tensile Strength, MPa (psi) 11.4 (1,650) 11.0 (1,600) 11.7 (1,700) 6.4 (925) 6.4 (925) 6.7 (975) Elongation at Break, % Hardness, durometer A mm x 4.0 mm 70 hr at 24 C (75 F) hr at 200 C (392 F) hr at 200 C (392 F) hr at 232 C (450 F)

5 Table 4A VPA No. 3 Processing Aid in Viton E-45 and Viton E-60 Compound 4A 4B 4C 4D 4E 4F Viton E Viton E MT Black (N908) High-activity MgO Calcium Hydroxide Viton Curative No Viton Curative No VPA No Mooney Scorch, MS at 121 C (250 F) Original Units, minimum Time to 10-pt rise, min >30 >30 >30 >30 >30 >30 Mooney Scorch, MS at 121 C (250 F) After Aging 7 days at 38 C (100 F) and 100% Relative Humidity Units, minimum Time to 10-pt rise, min ODR at 177 C (350 F), Microdie, 3 Arc, 12 min M L, N m (in Ib) 1.2 (11) 1.2 (11) 1.2 (11) 1.4 (12) 1.5 (13) 1.6 (14) t s 0.23 (t s 2), min t c 90, min M H, N m (in Ib) 8.8 (78) 8.6 (76) 8.4 (74) 13.8 (122) 13.9 (123) 13.6 (120) After press cure After post-cure % Modulus, MPa (psi) 4.3 (620) 4.6 (670) 4.5 (650) 5.9 (860) 6.3 (910) 6.2 (900) Tensile Strength, MPa (psi) 12.2 (1,770) 11.5 (1,670) 11.8 (1,710) 12.1 (1,750) 12.6 (1,830) 12.5 (1,810) Elongation at Break, % Hardness, durometer A Stress/Strain at 23 C (73 F) After Aging 7 days at 275 C (528 F) 100% Modulus, MPa (psi) 3.0 (440) 3.3 (480) 3.3 (480) 4.7 (680) 4.7 (680) 4.9 (710) Tensile Strength, MPa (psi) 6.4 (930) 6.4 (930) 6.5 (940) 7.9 (1,140) 7.4 (1,070) 8.0 (1,160) Elongation at Break, % Hardness, durometer A mm x 3.5 mm 70 hr at 23 C (73 F) hr at 200 C (392 F) hr at 232 C (450 F)

6 Table 4B VPA No. 3 Processing Aid in Viton B-50 and Viton GF Compound 4G 4H 4I 4J 4K 4L Viton B Viton GF MT Black (N908) High-activity MgO Calcium Hydroxide Sublimed Litharge Diak No Viton Curative No Viton Curative No Luperco XL VPA No Mooney Scorch, MS at 121 C (250 F) Original Units, minimum Time to 10-pt rise, min >30 >30 > Mooney Scorch, MS at 121 C (250 F) After Aging 7 days at 38 C (100 F) and 100% Relative Humidity Units, minimum Time to 10-pt rise, min ODR at 177 C (350 F), Microdie, 3 Arc, 12 min (for Viton B-50), 30 min (for Viton GF) M L, N m (in Ib) 1.4 (12) 1.6 (14) 1.6 (14) 2.0 (18) 2.4 (21) 2.2 (19) t s 0.23 (t s 2), min t c 90, min M H, N m (in Ib) 9.8 (87) 9.3 (82) 9.2 (81) 7.9 (70) 9.5 (84) 8.9 (79) After press cure After post-cure % Modulus, MPa (psi) 6.2 (900) 6.2 (900) 6.3 (910) 7.3 (1,060) 8.6 (1,250) 9.0 (1,300) Tensile Strength, MPa (psi) 11.8 (1,710) 12.1 (1,760) 12.9 (1,870) 17.4 (2,520) 16.4 (2,380) 19.0 (2,750) Elongation at Break, % Hardness, durometer A Stress/Strain at 23 C (73 F) After Aging 7 days at 275 C (528 F) 100% Modulus, MPa (psi) 3.4 (490) 3.4 (490) 3.4 (490) 2.8 (410) 3.9 (570) 3.8 (550) Tensile Strength, MPa (psi) 5.9 (860) 6.0 (870) 5.9 (860) 7.6 (1,100) 9.1 (1,320) 8.8 (1,280) Elongation at Break, % Hardness, durometer A mm x 3.5 mm 70 hr at 23 C (73 F) hr at 200 C (392 F) Atochem, Buffalo, NY Note: Viton B-50 and Viton GF tested in separate evaluations. 6