additives | Surface modifi cation
olefi n-based additive designed for immediate lubrica- tion and for improved wear resistance compared to particulate-based alternatives and that does not exhibit the plateout associated with PTFE, according to the company. Laurel Products, headquartered in Pennsylvania in the US, specialises in fl uoropolymer additives to enhance wear performance, friction, and other properties. The company’s fl uorinated mica additive, Thor-FPz, imparts both the properties of a mica (hardness and abrasion resistance) and of a fl uoropoly- mer (low coeffi cient of friction, low surface energy). The additive has been used in various engineering polymer matrices (for example, PTFE, PA, and POM) in applica- tions including gears, ball-valve seats, and slide pads. “Laurel has quadrupled its production and sales of this unique additive since it was commercialised in 2014, and wear-reducing applications and opportunities continue to emerge in the compounding marketplace,” says James Downing, business director at Laurel. Laurel’s Marzon fl uoroadditives are said to be
specially processed to improve specifi c properties, including a heat-treatment to improve thermal stability, thermal-vibratory processing to improve particle morphology and fl owability, and the addition of hydrophilic molecules to optimise polarity and dispers- ability. The company’s latest addition is Marzon 638, a polysiloxane-infused PTFE additive that is claimed to feature silicone/fl uoropolymer chemistry within each discrete particle that provides both chemical and mechanical benefi ts. Solvay Specialty Polymers produces PTFE micron-
ised powders (Polymist and Algofl on L) and PFPE fl uids (Fomblin, Fluorolink, and Galden). “PTFE leverages the hydrophobicity and low surface tension of the material to impart enhanced tribological properties to the matrix,”
Table 1: Typical polymers used in wear-resistant applications
High-performance (higher temperature resistant) polymers: Polyetheretherketone (PEEK) Polyphenylene sulfi de (PPS) Polyphthalamide (PPA) Polyethersulfone (PES) Polyimide (PI)
Technical or engineering polymers: Polyketone (PK) Polyamide (PA) Acetal or Polyoxymethylene (POM)
says David Gibala, global business development manager at the company. The powder additive can be compounded directly or using a masterbatch of up to 40% to produce formulated compounds, which typically contain 10-20% PTFE, in a range of engineering and high-performance polymers. Special grades of micron- ised PTFE are optimised to withstand the high tempera- tures needed to compound PEEK and other high-melting specialty polymers. The company says PTFE does not migrate from the polymer, and its lubricating effect is most effi cient following a short “wear in” period. PFPE fl uids, on the other hand, are used at low levels (less than 1%) and bloom quickly to form a thin lubricating layer at the surface. Solvay’s fully fl uori- nated material can be compounded at temperatures up to 280°C. The company also offers PFPE with hydrogen- ated end groups that allow better compatibility in the matrix. The polarity of the end groups can be designed to modulate blooming rate for a specifi c matrix, according to Antonio Puppo, technical marketing for functional fl uids at Solvay Specialty Polymers. These grades have a maximum compounding temperature of 250°C. PFPE oils should be added to the compounding process as a masterbatch, suggests Puppo.
Colloids, a UK masterbatch producer that opened a manufacturing facility in Chanshu in China in May of this year, offers high-end, friction-modifying masterbatches for engineering resins under the brandname PACE. “Graphite is the preferred type of low-friction additive in aqueous applications, whereas molybdenum disulphide is the material of choice where the component parts are in contact with metal surfaces,” says Bob Thomas, technical director at the company. The company also produces a range of low-friction masterbatches
Table 2: Tribological test results of PC versus POM Source: RTP Company
42 COMPOUNDING WORLD | November 2015
containing silicone oil, erucamide or oleamide fatty acids. Silicone oil offers high temperature resistance making it suitable for use in engineering polymers. Erucamide and oleamide are only suitable for polyolefi n applications. “Choosing the correct additives and the correct level
www.compoundingworld.com
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52 |
Page 53 |
Page 54 |
Page 55 |
Page 56 |
Page 57 |
Page 58 |
Page 59 |
Page 60 |
Page 61 |
Page 62 |
Page 63 |
Page 64 |
Page 65 |
Page 66 |
Page 67 |
Page 68 |
Page 69 |
Page 70 |
Page 71 |
Page 72 |
Page 73 |
Page 74 |
Page 75 |
Page 76 |
Page 77 |
Page 78 |
Page 79 |
Page 80 |
Page 81 |
Page 82 |
Page 83 |
Page 84 |
Page 85 |
Page 86 |
Page 87 |
Page 88 |
Page 89 |
Page 90 |
Page 91 |
Page 92
