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Combined metallocene and gas-phase technology creates high Mooney EPDM
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FEATURE
Combined metallocene and gas-phase technology creates high Mooney EPDM Edited by Simon Atkinson This brief feature reports on two materials that have been recently launched by DuPont Dow Elastomers, whose physical characteristics and properties make them suitable for sealing applications. DuPont Dow Elastomers has broken new ground in ethylene propylene diene terpolymer (EPDM) by introducing the first of its new Nordel MG grades that offer high Mooney viscosity (over 100), without the need for oil extenders. The new grade enables rubber fabricators to achieve shorter mixing cycles because of the granular form, add 20% more fillers in
applications such as hose and automotive weatherstrip, and improve overall economics (Figures 1 and 2).
New areas of use “Combining metallocene technology with gasphase EPDM production allows the company to break new ground in EPDMs, and open up new
areas of use for high Mooney polymers that previously had limited application,” said Torkel Rhenman, DuPont Dow’s Nordel Global Business Director. He says that processors often use high Mooney grades to extend their compounds and create material systems at a lower cost without compromising performance requirements. Furthermore, the new technology offers a costeffective approach to achieving high Mooney capability.
Strong EPDM growth The company predicts that very high Mooney EPDM will grow at between 20% and 30%
Figure 1. The new high Mooney metallocene gas-phase Nordel MG grade meets typical compression set requirements at very high compound extension. The graph shows C/set (cooling-in-clamps method) – 22 h at 70°C versus Total phr.
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Figure 2. The new high Mooney metallocene gas-phase Nordel MG grade retains physical performance at 20% higher compound extension compared with typically used polymers.
Viton fluoroelastomers tackle chemical process sealing DuPont Dow Elastomers recently introduced, in commercial quantities, its new generation Viton fluoroelastomers that are made using the ‘advanced polymer architecture’ (APA). The Viton specialty types deliver significant improvements in part and processing performance, and meet rigorous sealing requirements in the chemical and hydrocarbon processing industries, claims the company (Figure 3). Polymerization and curing technology The advances are the result of a US$50 million investment in proprietary new polymerization and curing technology at DuPont Dow’s facility in
Dordrecht, The Netherlands. According to the company, Viton made with APA will endow valve seals, pump diaphragms and process system tubing with greater robustness, and enhanced chemical, heat and pressure resistance, leading to longer seal service life and lower maintenance costs (Figure 4). “We have developed several new APA polymers to meet the special needs of chemical processors, plant managers and maintenance engineers. Of these, the Viton GBL-S type is a special candidate, upgraded to provide improved resistance to acids such as concentrated sulphuric acid, and to hot water and steam where it
Figure 4. Diaphragm seals used in chemical process pumps and valves must resist aggressive chemicals, solvents, acids and steam, and maintain flex life at extreme temperatures. Pump and valve seals in Viton fluoroelastomers offer long-term flexibility for temperatures well below –40°C to more than 150°C, and resistance to aggressive process media.
excels without the need for toxic lead oxide to counter swell,” says Patrick Lederer, Viton’s European marketing manager. “Like all the new polymers, GBL-S offers enhanced seal force retention and compression set resistance.”
Figure 3. Sealing parts in new Viton GBL-S fluoroelastomer, made with ‘advanced polymer architecture’ (APA), exhibit virtually no change in tensile strength and improved elongation at break (when exposed to 96% concentrated sulphuric acid after one week at 70°C), compared with previous generation Viton GBL. The use of this material leads to longer seal service life and lower maintenance costs.
Sealing Technology January 2003
Peroxide cured The first new types being offered by the company are peroxide cured, including Viton GF-S, GBL-S, GLT-S, GBLT-S and GFLT-S types. These are followed by TBR-S and IBR-S base resistant types and Viton Extreme ETP-S providing resistance to caustics and other high-pH chemicals as well as low temperature flexibility.
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PATENTS percent per year. To meet such demand, the company intends to create a grade slate of high molecular weight polymers that will cover most customer needs, such as high green strength or extremely low temperature applications.
Gas-phase metallocene production Rhenman explains that such grades cannot be made through the conventional EPDM manufacturing process – it is gas-phase metallocene production that makes it possible. In the conventional approach or suspension process, oil must be added during manufacture to enable very high molecular weight and viscosity polymers to be processed. With Nordel MG, this is no longer necessary.
Patents Polymeric foam gaskets and seals Applicant: Chemque Inc, Canada This invention comprises an electrically conductive flexible polyurethane foam comprising a polyurethane and at least one conductive filler dispersed therein. The filler is present in an amount effective to provide EMI/RFI shielding, where the polyurethane comprises an isocyanate component and an active hydrogen component in a ratio of at most 0.20:1. The foam preferably has a maximum compression deflection value at 50% compression of about 25 psi, a maximum foam density of 0.95 g/cm 3 , and/or noise shielding effectiveness at a frequency of about 20 to about 1000 MHz of at least about 10 dB. Patent number: WO 02/089151 Inventor: A. Botrie Publication date: 7 November 2002
Optical fibre seal Applicants: Tyco Electronics Raychem NV, Belgium and Tyco Electronics UK Ltd, UK A method is provided for sealing a container into which optical fibres are fed. A portion of the optical fibres is accommodated between two strips that are sealed together by applying heat and/or pressure. The strips are then placed in an opening of the container and the container is sealed. The strips, which may be made of plastic, support the fibres while providing an excellent seal. Patent number: WO 02/088813 Inventors: S. Leeman, J. Watte, W. Mattheus, P. Van Overmeir Publication date: 7 November 2002
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Tests Customers testing the Nordel MG grade have validated the claimed benefits, including excellent surface finish achieved in extruded products resulting from the low gel in the new-gas phase polymers. In addition, Nordel MG grades in granular form are claimed to save compounders as much as 30% in mixing cycle time compared with baled EPDM. This also eliminates an entire step in thermoplastic vulcanizate (TPV) compounding, because no bale grinding is needed.
Product line
47130, extends the family of other grades (MG 47085 and MG 37060) which have already been introduced. The new line complements the proven performance of the Nordel IP family of products that have established a new benchmark in EPDM consistency, cleanliness, colour and appearance since their introduction during 1997. For more information, contact: DuPont Dow Elastomers LLC, 300 Bellevue Parkway, Suite 300, Wilmington, DE 19809, USA. Tel: +1 302 792 4200, Fax: +1 302 792 4450.
The Nordel MG product line incorporates carbon black. The new grade, designated MG
Or contact: DuPont Dow Elastomers SA, 2 chemin du Pavillon, CH-1218 Le Grand-Saconnex, Geneva, Switzerland. Tel: +41 22 717 4000, Fax: +41 22 717 4001.
Pipe seal
Mechanical seal
Applicant/Inventor: J.R. Newton, UK A pipe seal is disclosed which comprises a main body portion adapted to be fixed to the wall of a chamber, tank or the like. A face plate is adapted to be secured to the body portion which surrounds, in use, a pipe to be sealed. The body and face plate between them house a deformable member in contact with a seal, such that on forcing the face plate towards the body portion, the deformable member, in use, deforms and presses the seal into sealing contact with the pipe. The design of this pipe seal allows the pipe to enter the chamber wall at an angle of, for example, up to 12° from a right angle. Hence the end of a pipe could generate a cone of movement with an included angle of 24°. The seal therefore permits considerable positional movement of the pipe to allow connection of the pipe to its termination point within the chamber. Patent number: WO 02/088588 Publication date: 7 November 2002
Applicant: Safematic Oy, Finland The invention relates to an arrangement in connection with a mechanical seal that comprises at least two sliding surfaces pressing against each other, which are arranged to seal a gap between a rotating and a non-rotating machine part, and a means for providing a sealing fluid flow to cool the sliding surfaces. To provide an optimal consumption of sealing fluid, a valve assembly is attached to the assembly for providing the cooling sealing fluid flow. The valve assembly reacts to the temperature of the seal and opens and closes the flow of sealing fluid according to the cooling need. Patent number: WO 02/088553 Inventors: H. Trygg, E. Salovaara Publication date: 7 November 2002
Dry gas seal Applicant: Corac Group Plc, UK A gas seal assembly comprises a pair of mutually rotatable sealing members, each of which has a face adjacent to a gap between the two members. One of the members is urged in a direction attempting to close the gap, which constitutes a leakage path through the seal assembly. A gas bleed arrangement allows gas from the high pressure side of the seal assembly to bleed into the gap at a position radially spaced between the inner diameter of the members and the outer diameter of the members so as to apply a force tending to separate the members, with the force decreasing as the size of the gap increases. Patent number: WO 02/088578 Inventor: J.R. Gozdawa Publication date: 7 November 2002
Polyurea elastomeric system Applicant: Urethane Products Corp, USA A polyurea composition free from polyol linkages is disclosed. A composition and process are described for producing a two-component spray 100% polyurea elastomeric system wherein components A and B are mixed. Component A is a prepolymer produced by an aromatic isocyanate and amine-terminated materials, while component B comprises 100% amine-terminated reactive ingredients. The invention can be used as a spray system for lining and coating surfaces. Patent number: WO 02/088210 Inventors: A. Zahariadis, G. Thermos Publication date: 7 November 2002
Electropneumatic control valve seal Applicant: Knorr-Bremse, Germany The invention describes an electropneumatic control valve for a compressed air braking system on a vehicle with a relay valve housing, in which is arranged an axially displaceable control
Sealing Technology January 2003
22/01/2003
15:19
Page 10
FEATURE
Combined metallocene and gas-phase technology creates high Mooney EPDM Edited by Simon Atkinson This brief feature reports on two materials that have been recently launched by DuPont Dow Elastomers, whose physical characteristics and properties make them suitable for sealing applications. DuPont Dow Elastomers has broken new ground in ethylene propylene diene terpolymer (EPDM) by introducing the first of its new Nordel MG grades that offer high Mooney viscosity (over 100), without the need for oil extenders. The new grade enables rubber fabricators to achieve shorter mixing cycles because of the granular form, add 20% more fillers in
applications such as hose and automotive weatherstrip, and improve overall economics (Figures 1 and 2).
New areas of use “Combining metallocene technology with gasphase EPDM production allows the company to break new ground in EPDMs, and open up new
areas of use for high Mooney polymers that previously had limited application,” said Torkel Rhenman, DuPont Dow’s Nordel Global Business Director. He says that processors often use high Mooney grades to extend their compounds and create material systems at a lower cost without compromising performance requirements. Furthermore, the new technology offers a costeffective approach to achieving high Mooney capability.
Strong EPDM growth The company predicts that very high Mooney EPDM will grow at between 20% and 30%
Figure 1. The new high Mooney metallocene gas-phase Nordel MG grade meets typical compression set requirements at very high compound extension. The graph shows C/set (cooling-in-clamps method) – 22 h at 70°C versus Total phr.
10
Sealing Technology January 2003
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FEATURE
Figure 2. The new high Mooney metallocene gas-phase Nordel MG grade retains physical performance at 20% higher compound extension compared with typically used polymers.
Viton fluoroelastomers tackle chemical process sealing DuPont Dow Elastomers recently introduced, in commercial quantities, its new generation Viton fluoroelastomers that are made using the ‘advanced polymer architecture’ (APA). The Viton specialty types deliver significant improvements in part and processing performance, and meet rigorous sealing requirements in the chemical and hydrocarbon processing industries, claims the company (Figure 3). Polymerization and curing technology The advances are the result of a US$50 million investment in proprietary new polymerization and curing technology at DuPont Dow’s facility in
Dordrecht, The Netherlands. According to the company, Viton made with APA will endow valve seals, pump diaphragms and process system tubing with greater robustness, and enhanced chemical, heat and pressure resistance, leading to longer seal service life and lower maintenance costs (Figure 4). “We have developed several new APA polymers to meet the special needs of chemical processors, plant managers and maintenance engineers. Of these, the Viton GBL-S type is a special candidate, upgraded to provide improved resistance to acids such as concentrated sulphuric acid, and to hot water and steam where it
Figure 4. Diaphragm seals used in chemical process pumps and valves must resist aggressive chemicals, solvents, acids and steam, and maintain flex life at extreme temperatures. Pump and valve seals in Viton fluoroelastomers offer long-term flexibility for temperatures well below –40°C to more than 150°C, and resistance to aggressive process media.
excels without the need for toxic lead oxide to counter swell,” says Patrick Lederer, Viton’s European marketing manager. “Like all the new polymers, GBL-S offers enhanced seal force retention and compression set resistance.”
Figure 3. Sealing parts in new Viton GBL-S fluoroelastomer, made with ‘advanced polymer architecture’ (APA), exhibit virtually no change in tensile strength and improved elongation at break (when exposed to 96% concentrated sulphuric acid after one week at 70°C), compared with previous generation Viton GBL. The use of this material leads to longer seal service life and lower maintenance costs.
Sealing Technology January 2003
Peroxide cured The first new types being offered by the company are peroxide cured, including Viton GF-S, GBL-S, GLT-S, GBLT-S and GFLT-S types. These are followed by TBR-S and IBR-S base resistant types and Viton Extreme ETP-S providing resistance to caustics and other high-pH chemicals as well as low temperature flexibility.
11
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PATENTS percent per year. To meet such demand, the company intends to create a grade slate of high molecular weight polymers that will cover most customer needs, such as high green strength or extremely low temperature applications.
Gas-phase metallocene production Rhenman explains that such grades cannot be made through the conventional EPDM manufacturing process – it is gas-phase metallocene production that makes it possible. In the conventional approach or suspension process, oil must be added during manufacture to enable very high molecular weight and viscosity polymers to be processed. With Nordel MG, this is no longer necessary.
Patents Polymeric foam gaskets and seals Applicant: Chemque Inc, Canada This invention comprises an electrically conductive flexible polyurethane foam comprising a polyurethane and at least one conductive filler dispersed therein. The filler is present in an amount effective to provide EMI/RFI shielding, where the polyurethane comprises an isocyanate component and an active hydrogen component in a ratio of at most 0.20:1. The foam preferably has a maximum compression deflection value at 50% compression of about 25 psi, a maximum foam density of 0.95 g/cm 3 , and/or noise shielding effectiveness at a frequency of about 20 to about 1000 MHz of at least about 10 dB. Patent number: WO 02/089151 Inventor: A. Botrie Publication date: 7 November 2002
Optical fibre seal Applicants: Tyco Electronics Raychem NV, Belgium and Tyco Electronics UK Ltd, UK A method is provided for sealing a container into which optical fibres are fed. A portion of the optical fibres is accommodated between two strips that are sealed together by applying heat and/or pressure. The strips are then placed in an opening of the container and the container is sealed. The strips, which may be made of plastic, support the fibres while providing an excellent seal. Patent number: WO 02/088813 Inventors: S. Leeman, J. Watte, W. Mattheus, P. Van Overmeir Publication date: 7 November 2002
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Tests Customers testing the Nordel MG grade have validated the claimed benefits, including excellent surface finish achieved in extruded products resulting from the low gel in the new-gas phase polymers. In addition, Nordel MG grades in granular form are claimed to save compounders as much as 30% in mixing cycle time compared with baled EPDM. This also eliminates an entire step in thermoplastic vulcanizate (TPV) compounding, because no bale grinding is needed.
Product line
47130, extends the family of other grades (MG 47085 and MG 37060) which have already been introduced. The new line complements the proven performance of the Nordel IP family of products that have established a new benchmark in EPDM consistency, cleanliness, colour and appearance since their introduction during 1997. For more information, contact: DuPont Dow Elastomers LLC, 300 Bellevue Parkway, Suite 300, Wilmington, DE 19809, USA. Tel: +1 302 792 4200, Fax: +1 302 792 4450.
The Nordel MG product line incorporates carbon black. The new grade, designated MG
Or contact: DuPont Dow Elastomers SA, 2 chemin du Pavillon, CH-1218 Le Grand-Saconnex, Geneva, Switzerland. Tel: +41 22 717 4000, Fax: +41 22 717 4001.
Pipe seal
Mechanical seal
Applicant/Inventor: J.R. Newton, UK A pipe seal is disclosed which comprises a main body portion adapted to be fixed to the wall of a chamber, tank or the like. A face plate is adapted to be secured to the body portion which surrounds, in use, a pipe to be sealed. The body and face plate between them house a deformable member in contact with a seal, such that on forcing the face plate towards the body portion, the deformable member, in use, deforms and presses the seal into sealing contact with the pipe. The design of this pipe seal allows the pipe to enter the chamber wall at an angle of, for example, up to 12° from a right angle. Hence the end of a pipe could generate a cone of movement with an included angle of 24°. The seal therefore permits considerable positional movement of the pipe to allow connection of the pipe to its termination point within the chamber. Patent number: WO 02/088588 Publication date: 7 November 2002
Applicant: Safematic Oy, Finland The invention relates to an arrangement in connection with a mechanical seal that comprises at least two sliding surfaces pressing against each other, which are arranged to seal a gap between a rotating and a non-rotating machine part, and a means for providing a sealing fluid flow to cool the sliding surfaces. To provide an optimal consumption of sealing fluid, a valve assembly is attached to the assembly for providing the cooling sealing fluid flow. The valve assembly reacts to the temperature of the seal and opens and closes the flow of sealing fluid according to the cooling need. Patent number: WO 02/088553 Inventors: H. Trygg, E. Salovaara Publication date: 7 November 2002
Dry gas seal Applicant: Corac Group Plc, UK A gas seal assembly comprises a pair of mutually rotatable sealing members, each of which has a face adjacent to a gap between the two members. One of the members is urged in a direction attempting to close the gap, which constitutes a leakage path through the seal assembly. A gas bleed arrangement allows gas from the high pressure side of the seal assembly to bleed into the gap at a position radially spaced between the inner diameter of the members and the outer diameter of the members so as to apply a force tending to separate the members, with the force decreasing as the size of the gap increases. Patent number: WO 02/088578 Inventor: J.R. Gozdawa Publication date: 7 November 2002
Polyurea elastomeric system Applicant: Urethane Products Corp, USA A polyurea composition free from polyol linkages is disclosed. A composition and process are described for producing a two-component spray 100% polyurea elastomeric system wherein components A and B are mixed. Component A is a prepolymer produced by an aromatic isocyanate and amine-terminated materials, while component B comprises 100% amine-terminated reactive ingredients. The invention can be used as a spray system for lining and coating surfaces. Patent number: WO 02/088210 Inventors: A. Zahariadis, G. Thermos Publication date: 7 November 2002
Electropneumatic control valve seal Applicant: Knorr-Bremse, Germany The invention describes an electropneumatic control valve for a compressed air braking system on a vehicle with a relay valve housing, in which is arranged an axially displaceable control
Sealing Technology January 2003