JULY 2011 3

F O C U S O N P O W D E R C O A T I N G S

increasing cure temperaturessince the melt viscosities wouldbe higher at lower curetemperatures, which could hinderthe formations of crosslinkingbetween the polymer chains.There seems to be littleimprovement between the 3% andthe 5% level of addition.

Tests carried out on the curedfilms using the simple pull-offmethod for assessing adhesionand hardness measured byPersoz and Konig showed amarked increase in the pull-offtests applied to the untreatedpowder coating from 210 psi to827 psi for the 3% modified film,while at 5% the figure was quotedas 561 psi, and the hardness(Persoz) increased progressivelyfrom 413s for the untreatedspecimen to 444s for the 5%modification, and the Konigreadings from 49s to 71s at 5%.

These test results will be ofconsiderable interest to powderformulators for they offer a simplemethod for reducing energy costsand improving overall filmperformance.

Article entitled “Effect of Nano-sized CalciumCarbonate on Cure Kinetics and Properties ofPolyester/epoxy Blend Powder Coatings” byresearchers at several Iranian Universitiespublished in Progress in Organic Coatings, Jun2011, 71 (2), 173-180

Renewable or recycled rawmaterials for polyester powdercoatings

A paper presented at the recentEuropean Coatings Congress byAlessandro Minesso of Cytecdescribed the latest developmentsof powder coatings polyestersbased on renewable and/orrecycled raw materials.

The author does not mentionany of the recycled or renewableraw materials used in theevaluation programme, but it islikely that the polyol componentsare renewable from bio-basedsources while both acids andpolyol could be recovered byrecycling the components ofpolyethylene terephthalate (PET)plastics which are used for plasticbottles and packaging,

representing a large and valuablesource for recycling

Cytec researchers produced anumber of polyester resins basedon these materials includinghybrid grades capable of thermalcure with various ratios of a threetype solid epoxy resin. Threehybrid formulations are shown: (1)a 70:30 ratio of polyester:epoxy,(2) a 60:40 blend; and (3) a75:25 combination. Resin 1 wasalso formulated in combinationwith Primid XL 552 in the ratio95:5. Resin 4 was also evaluatedas a polyurethane powder coatingwhen combined with Vestagon B1530 in the ratio 85:15. Resin 5,described as an unsaturatedpolyester, was formulated as aUV curable powder system. Allformulated powder coatings werepigmented with titanium dioxidealone, except for the Primidsystem which was pigmented toRAL 8014 brown.

The prepared powder coatingswere applied to steel panels, andchromated aluminium panels forthe RAL 8014 system, thenstoved at 180°C for 10 minutes.The UV curable powder coatingwas given its own curing schedule(not disclosed and no resultsprovided).

Tests carried out on the hybridpowder systems against a standardproduct based on non-renewableraw materials showed comparableperformance with respect to pencilhardness, adhesion, gloss beforeand after the boiling water test,and gloss reduction after exposuretests. There were, however, somenotable improvements. The system(1) hybrid gave direct and impactresults of 200/200 compared to140/140 for the standard, and theT-bend test was assessed at 0-Tcompared to 1-T for the standard.In fact all resins from 1 to 5complied with 0-T for the T-bendtest. Additionally, all of the newresins gave improved performancein the blooming test at 120°C.

Outdoor weather resistancewas assessed for the Primidsystem in QUV-A and QUV-Bexposure and the performancewas in line with that of a standard

polyester powder coating foroutdoor general applications.

It was concluded that thesenew resins offered the benefits ofreduced energy consumption,shorter reaction time, and reducedwaste. A recently developedthermoset resin shows excellentflexibility and T-bending even aftersix months of ageing and offerspotential for coil coatingapplications. It can also offer FDAapproval for a low temperaturecuring coating in the can coatingmarket.

Paper entitled “Polyesters for PowderCoatings in a Sustainable Economy” byAlessandro Minesso of Cytec presented atEuropean Coatings Congress in Nuremberg,28-30 Mar 2011. Copies of the Congresspapers are available in CD format from theorganizers Vincentz Network. Website:http://www.european-coatings-show.com

INDUSTRYNEWS

High volumes boost profits atJotun: 2010

Norwegian paint producer Jotunposted a pre-tax profit of NKR1.30 bn (€167 M) in 2010, up19% from NKR 1.09 bn in 2009,while revenue increased to NKR12 bn from NKR 11.2 bn, on theback of volume gains in allbusiness segments. Jotuninvested a total of NKR 600 M in2010 in projects including a newplant at Vindal in Sadefjord,Norway; a plant and distributionfacility in Malaysia and Singapore;a new coatings plant in Qingdao,China; and a powder coatingsplant in Zhangjiagang, China. Thecompany will also invest in a newwaterborne plant in Saudi Arabia.

European Paint and Resin News, Mar 2011,49 (3), 2 (Website: http://www2.pra-world.com/)

Clariant supports emergingmarkets with performance-powering innovations

Clariant’s commitment to supportcustomers in emerging marketswith the latest efficiency-