Filament winding. Continuous and discontinuous production

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1 Filament winding Continuous and discontinuous production Introduction AkzoNobel is the world s leading producer of organic peroxides for the curing of thermoset resins, coatings and specialty monomers. We re home to the best known brands in the thermoset market, examples include Butanox, Perkadox and Trigonox. We also have a whole range of auxiliary products, such as accelerators and promoters, to meet your specific production requirements. Reason for our products High quality Good after sales and technical service Intensive safety research Worldwide distribution Customized application research: special formulated products for an optimal performance in this application Leading edge technology for Cobaltfree curing systems As worldwide leading producer of organic peroxides AkzoNobel Functional Chemicals is dedicated to produce and develop best in class products to meet the needs of our customers. This application guide introduces you to our thermoset product portfolio and helps you find a suitable curing system for your specific application. If you need more detailed information please contact us. Application The Glass Fibre Reinforced (GRP) pipes production is a significant market segment comprising several production methods. A major application is the so called (Drostholm) continuous filament winding process using a continuous mandrel and external heating on the pipe and the second method is the discontinuous filament winding process with a fixed mandrel. Both methods require a specific cure system for optimal cure and maximum machine output

2 Filament winding 2 AkzoNobel curing agents Our product range for filament winding of pipes evolved from the industry standard (Butanox M-50 and Butanox M-60) to the development of special peroxides to Trigonox 269 (for increased line speed), and Trigonox 279 (to achieve maximum line speed and also zero residual styrene after the cure). Also there is Trigonox 249VR for peak reduction when manufacturing thick laminates. We can also offer curing systems for potable water pipes. In this respect we would provide samples and analysis data to the end customer and the authorities for approval activities. In this application guide the various peroxides will be discussed. Main end products The pipes are for example manufactured for desalination plants and for water transport (potable and waste water) but also for the chemical industry where chemical resistance of the inner wall of the pipe is important. Process equipment for continuous filament winding The equipment needed for the continuous production of GRP pipes are commonly known as the Drostholm machine which operates with a continuous (endless) mandrel. Process equipment for discontinuous filament winding The discontinuous production is done with a fixed mold on which the glass is winded. Schematic set up Mandrel Resin bath Rovings Curing systems Below we have listed the most commonly used peroxides for filament winding. All peroxides are used in combination with a Cobalt accelerator which are also part of our product portfolio.

3 Filament winding 3 Peroxides for continuous filament winding Butanox M-50 Butanox M-60 Medium reactive MEKP Trigonox 269 Special peroxide mixture for 20 increased line speed compared to Butanox M-50 Trigonox 279 Trigonox 249VR Faster line speed than Trigonox 269 (i.e. 30 over Butanox M-50) and also enabling very efficient curing leading to zero residual styrene content (a postcure is not needed anymore). This way post cure deformation is avoided and optimal form stability is achieved. A medium reactive curing system with a reduced peak exotherm. Especially for manufacturing thick laminates. To get a better understanding of the speed of curing of the various curing systems in continuous filament winding we show below the timetemperature curve for all them. The figure shows the curing at 80 C of an orthophthalic resin (50 filled with quartz sand). Peroxides for discontinuous filament winding Butanox M-50 Butanox M-60 Standard medium reactive MEK-peroxide Trigonox 63 Trigonox 65 For a faster cure Trigonox 63 or Trigonox 65 can be used which are mixtures of MEKP and AAP. Trigonox 44B A very fast curing system can be achieved by using Trigonox 44B which is only AAP. Trigonox 249VR A medium reactive curing system with a reduced peak exotherm. Especially for manufacturing thick laminates. Peroxides for curing vinylester resins In some pipes the wall and/or the liner is made with an epoxy based vinylester resin. This type of resin is preferably not cured with a standard MEKP as this generates gas bubbles in the laminate which reduced the mechanical properties of the pipe. This gassing can be easily avoided by using a different type of peroxide. Below you find the recommended curing systems for VE resins: Trigonox 239 Butanox LPT-IN High reactive curing system with a low peak exotherm. Trigonox 239 does not generate gas during curing. Standard medium reactive MEKP generating only small amount of gassing compared to standard MEKP. Trigonox K-90 Cure system for very thick vinylester laminates.

4 Filament winding 4 Tuning the curing system Other than with peroxides it is common practice to adjust the cure characteristics to cope with the local climate or with product design challenges. This is commonly achieved with our promoters and inhibitors. Promoters and inhibitors Promotor D Inhibitor NLC-10 Inhibitor NLD-20 Please note: Cobalt accelerators To increase the reactivity of a standard MEKP one can add small amounts of Promotor D to the resin To extend the geltime one can add small amounts of Inhibitor to the resin. To extend the geltime one can add small amounts of Inhibitor to the resin. The inhibitor captures (neutralizes) the first formed radicals this way preventing the gelling to start. Once all inhibitor has reacted with these first formed radicals it becomes inactive. All radicals that are formed then will start the gelling. As the inhibitor eats the first radicals one should take notice that sufficient peroxide is used in the curing system to compensate for that. In addition to the peroxides we offer Cobalt accelerators which are part of the curing systems. We have Accelerator NL-49P (1 Cobalt solution), Accelerator NL-51P (6 Cobalt solution) and Accelerator NL-53 (10 Cobalt solution) in our portfolio of which Accelerator NL-51P is most commonly used to pre-accelerate the resins for pipes production. This allows optimal flexibility to set the reactivity of the resin to fit the seasonal temperature fluctuation as well as for chances in reactivity of the used resins. Reactivity figures Please find below some reactivity data for the mentioned curing systems. The most common cure systems are Butanox M-50 and Butanox M- 60 and Butanox LPT-IN (the latter being also suitable for curing VE resins). The data relate to 4 mm laminates (30 glass). Butanox LPT-IN Cure of 4 mm laminates at 20 C 4 mm laminates have been made with a 450 g/m 2 glass chopped strand mat. The glass content in the laminates is 30wt. The intakes are referred to as phr (parts per 100 parts resin). Gel time Time to peak Peak exotherm C 2 phr Butanox LPT-IN phr Accelerator NL-49P 2 phr Butanox M phr Accelerator NL-49P phr Butanox LPT-IN phr Accelerator NL-49P 2 phr Butanox M phr Accelerator NL-49P Barcol (934-1) 0-5 hrs hrs Res. Styrene 24 hrs 20 C hrs 80 C <0.1 <0.1 Note: The residual styrene levels in the first column are measured after 24 hrs while leaving the laminate at 20 C. The second column gives the residual styrene levels when the laminate, after the 20 hrs at 20 C, is post cured for 8 hrs at 80 C. Cure of 4 mm laminates at 70 C The same laminates as above have been cured at 70 C but this time using less Accelerator NL-49P and a small amount of Inhibitor NLC-10. Butanox LPT-IN Accelerator NL-49P Inhibitor NLC-10 phr phr phr Gel time at 20 C (min) min 200 Cure data at 70 C Gel time Time to peak Peak exotherm Barcol hardness (10 min after peak exotherm) min min C min

5 Filament winding 5 Trigonox HMa and Trigonox 44B Trigonox HMa (MIBKP) and Trigonox 44B (AAP) are typically used for the thick laminates and couplings. Cure of 10 mm laminates at 20 C The testing is done for a 10 mm laminate to show the curing in comparison to Trigonox 44B and Butanox M-50. Gel time Time to peak Peak exotherm C 1 phr Trigonox 44B phr Accelerator NL-49P 1 phr Butanox M phr Accelerator NL-49P phr Trigonox 44B phr Accelerator NL-49P 1 phr Butanox M phr Accelerator NL-49P Barcol Hrs <1 <1 Res. Styrene 24 hrs 20 C hrs 80 C Note: The residual styrene levels in the first column are measured after 24 hrs while leaving the laminate at 20 C. The second column gives the residual styrene levels when the laminate, after the 20 hrs at 20 C, is post cured for 8 hrs at 80 C. The date show that Trigonox 44B has the same geltime as a Butanox M-50 but it gives a much faster curing and consequently a much higher peak exotherm. It is generally recommended to keep the peak exotherm below 100 C in order to prevent delamination and other shrinkage related problems. Below graph gives the relation between the thickness of the laminate and the corresponding peak exotherm for the curing systems using Trigonox 44B and Butanox M-50. The graph below shows the influence of the laminate thickness on the peak exotherm. The cure systems 1) and 2) have a gel time of 30 at 20 C: 1) 1 phr Trigonox 44B + 1 phr Accelerator NL-49P 2) 1 phr Butanox M phr Accelerator NL-49P Peak Exotherm ( C) Tx 44B + NL49P Btx M50 + NL49P Laminate thickness (mm)

6 Filament winding 6 Common problems and solutions Production speed The production speed of a continuous filament winding machine can be increased. The most commonly used cure system today is Butanox M-50 (a medium reactive MEKP) but, provided your dosing equipment can handle, faster systems are already available. For example Trigonox 269 which is 20 faster than Butanox M-50, and Trigonox 279 which is 30 faster than Butanox M-50 and also giving very low residual styrene levels (allowing to eliminate the post cure step). Technical data are given in this application guide. Samples and start up recipes are also available. For a discontinuous production line the production speed can be increased by using a faster peroxide. The common cure system is based on Butanox M-50 and the fastest alternative is Trigonox 44B. In case this is too fast you could choose for a mix (MEKP+AAP) peroxide such as Trigonox 61, Trigonox 63 or Trigonox 65. The limitation for a faster system is given by the peak exotherm which should preferable not exceed the 100 C. Cracks in the laminate Cracks are often caused by a too high peak exotherm. Especially when using a fast curing system on a high speed continuous machine the peak exotherm needs close monitoring. In the technical results in this application guide you can see that the cure speed can be tempered by using a slower peroxide. The fastest available cure system in the market is Trigonox 279 and the standard is Butanox M-50. There are several grades available with inbetween reactivity. Please check with us for a specific recommendation. Cracks can also be formed during the post cure step or in the months after production as a result of post cure shrinkage (i.e. styrene gradually reacting away causing shrinkage). In that case you are recommended to use a cure system which lowers the residual styrene levels immediately during curing to levels far below 1, such as Trigonox 279. In that case the residual styrene levels are very low directly after the curing step that a post cure is not needed. This safes costs in time, energy and handling. For more information EMEIA AkzoNobel Polymer Chemistry Velperwerg BM Arnhem The Netherlands T E polymerchemicals.nl@akzonobel.com Americas AkzoNobel Polymer Chemistry 525 West Van Buren Street Chicago, IL United States T (US only) T F E polymerchemicals.na@akzonobel.com Asia Pacific Akzo Nobel (Asia) Co. Ltd. 22F, Eco City No West Nan Jing Road Jing An District Shanghai P.R. China T F E polymerchemicals.ap@akzonobel.com Butanox, Perkadox and Trigonox are registered trademarks of Akzo Nobel Chemicals B.V. or affiliates in one or more territories. Blisters Blisters in the pipe wall are most of the cases formed as a result of bad wet out, or due to styrene evaporation when the peak exotherm is very high. In that case the temperature in the pipe reaches the boiling point of the styrene causing it to start gassing. Blisters are also sometimes formed when glass or other filler materials are very humid. In that case the water will start evaporating during the cure causing gas bubbles. Antistatic charging When pumping non-polar (non-electro conductive) solvents through a pipe there is a risk of building up static electricity in the pipe wall which can cause hazardous situation in case of a sudden discharge (spark). In order to allow the static energy to disappear the pipe should be made electro-conductive. This can be achieved by adding 1-3 Ketjenblack EC-300J to the resin. Ketjenblack EC-300J is a highly efficient conductive black which can decrease the resistivity to semi conductive levels (range Ohm.cm). Ketjenblack EC-300J is tested in various resins including Vinylester resins which gave excellent results. For the mixing step one should use a high shear mixer (cowles dissolver blade in normal reactor set up and a tip speed of 10 m/s) as dispersion of the Ketjenblack is key for success. ROW TS /December 2017 All information concerning this product and/or suggestions for handling and use contained herein are offered in good faith and are believed to be reliable. AkzoNobel Functional Chemicals, however, makes no warranty as to accuracy and/or sufficiency of such information and/or suggestions, as to the product's merchantability or fitness for any particular purpose, or that any suggested use will not infringe any patent. Nothing contained herein shall be construed as granting or extending any license under any patent. Buyer must determine for himself, by preliminary tests or otherwise, the suitability of this product for his purposes. The information contained herein supersedes all previously issued bulletins on the subject matter covered. The user may forward, distribute, and/or photocopy this document only if unaltered and complete, including all of its headers and footers, and should refrain from any unauthorized use. You may not copy this document to a website AkzoNobel Polymer Chemistry