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Dow Elastomers.qxp_Layout 1 28/11/2014 13:12 Page 1

HOTMELT TECHNOLOGY

Polyolefin elastomers boost end use performance of hot melt adhesives

Dr Burçak Conley, Dr Allan McLennaghan and Dr Selim Yalvac, Dow Elastomers, look at the growing market need for hot melt adhesives

he global adhesives mar - owners for high-performance ADHESIVE PERFORMANCE significant decrease in downtime ket accounted for 24bn lb solutions that deliver new and POE-based HMAs are better of machines compared to EVA- in 2013*, with hot melt improved application and per - adhesives. Due to their low initial based HMAs again bringing addi - adhesives (HMA) accounting for formance properties, is driving colour and good thermal stability tional operational cost saving. T15%, making it the third largest suppliers to deploy their efforts to of POE the end HMA has better segment behind water-based and boost the end use performance of colour compared to alternatives, PO-BASED ELASTOMERS solvent-based adhesives. The their hot melt adhesives solutions as well as a lack of odour, thus MEET HMA MARKET NEEDS HMA market is highly fragment - and, in doing so, providing a making them a great fit for both The was ed and includes more than 10 response to those challenges. packaging and hygiene applica - the first to introduce polyolefin- end-user applications, such as tions. POE-based HMAs can also based into hot melt packaging, non-woven, pressure POLYOLEFIN-BASED be applied on a variety of surfaces adhesive formulations some 15 sensitive adhesive and book bind - ELASTOMERS DELIVER and, due to the lower density and years ago. Since then, this HMA for - ing, as well as furniture and con - PERFORMANCE FOR HMA viscosity, they can provide great mulation produced with Dow’s Insite struction applications. Polyolefin elastomer (POE)-based adhesion, even if the POEs may Technology, has demonstrated signif - HMA give excellent performance not contain any polar functionality. icant advantages compared to the A RAPIDLY EVOLVING by surpassing EVA-based HMA for - use of traditional EVA-based HMAs. MARKET THAT BRINGS ITS mulations in three main categories: ENHANCED TOTAL COST The first introduced polyolefin- OWN CHALLENGES processability, adhesive perform - Overall, POE-based HMAs give based family was ethyl - The development of the global ance and reduced total cost. the formulators and brand owners ene-octene random copolymers hot melt adhesives industry is and packers improved mileage and with the brand name of Affinity being driven by a number of PROCESSING lower maintenance for a better GA POE ( figure 1 ). These random evolving trends. Packaging indus - POE-based HMAs deliver total cost and performance com - copolymers combine low crys - try brand owners and adhesive improved processing because of pared to EVA-based HMAs. Due tallinity and low density ( 0.887 ≤ formulators are faced with the their better thermal stability, result - to the improved thermal stability g/cc) with a very low viscosity. Due complex challenge of meeting ing in char-free and clean applica - and lower density of Affinity GA to Dow’s Insite Technology, poly - end-user demands for food safe - tion equipment. The low or no gel POE-based HMAs, the mileage mer architecture can be precisely ty, while ensuring the shelf formation reduces the applicator advantage can bring up to 30% controlled, so that the optimum appeal, cost efficiency and sus - downtime and gives a consistent saving. Also no need to change balance of the necessary amor - tainability of their solutions. adhesive application, resulting in nozzles and filters for Affinity GA phous properties and strength can Changes in consumer demo - improved running costs and POE-based HMAs resulted in a be achieved. Thanks to the higher graphics, notably as the popula - reduced scrap. There is also less tion ages, are adding factors, such wear and tear on the equipment, Fig 1. Affinity GA POE structure as enhanced wear and comfort primarily due to the lack of acidity to the growing list of demands in of the base polymer compared to the hygiene market. EVA resulting in extended lifetime The resulting relentless of filters and nozzles. Additionally, increase in the demand from the ease of cleaning from machin - adhesives formulators and brand ery and the lack of angel hair result in more savings through reduced Source: *DPNA, Kusumgar labour costs. Author: Dr Burçak Conley, Technical Service and Development Manager, Dow Elastomers, Bachtobelstrasse 3, 8810 Horgen, Switzerland. [email protected]; Dr Allan McLennaghan, Senior Technical Service & Development Specialist, Dow Elastomers, Bachtobelstrasse 3, 8810 Horgen, Switzerland. [email protected] Dr Selim Yalvac, Senior Research and Development Manager, Dow Elastomers, Texas Operations, 2301 Brazosport Blvd, Freeport, TX 77541-3257 USA. [email protected]; www.dowelastomers.com

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HOTMELT TECHNOLOGY

levels of incorporated octene co- sion performance , the glass transition tem - In line with the lifestyle peratures of these are demands of today’s consumers, lower than those of EVA grades food packages are exposed to dif - used in HMA formulations. This ferent temperature conditions makes the polymers more suitable from high temperature (eg hot fill for low temperature HMA appli - or pasteurisation) down to very cations ( figure 1 ). low temperature (eg frozen food). Fig 2. Above: Infuse OBC structure Since then, new classes of poly - HMA formulators are directing Fig 3. Below: Versify elastomer structure olefin-based elastomers have been efforts towards developing adhe - developed through Dow’s sives for this evolving market advanced knowledge in Insite trend, which will hold the package Technology to precisely control under a wide range of tempera - the molecular architecture of the ture conditions by giving increased polymers. One such breakthrough packaging security. was Infuse Olefin Block The success of Dow Affinity Copolymers (OBC) produced by GA-based HMA at low tempera - ‘chain shuttling technology’. These ture can be attributed to the low block polymers contain semi-crys - Tg of Affinity GA providing ductili - talline ‘hard blocks’ and elastomer - ty at low temperatures ( figure 4 ). ic ‘soft blocks’, making them unique However, if formulators are look - as POEs. The hard blocks provide a ing for solutions pushing the limits, high melting temperature, while one possible approach is to add the soft segments maintain the Infuse OBC 9807 into the HMA overall polymer elastic properties. formulation. The hard blocks in Among key differences Infuse will provide additional fibre between Infuse OBC and Styrenic tear at high temperature, while the Block Copolymers (SBC) are: soft blocks will give low tempera - ɀ SBCs are typically polymerised by ture bond flexibility ( figure 4 ). living anionic polymerisation condi - ɀ High speed packaging lines tions with a narrow molecular With an eye on cost effectiveness, weight distribution (Mw/Mn 1.0- the industry is moving towards ≈ 1.5) resulting in monodispersed new manufacturing lines offering Fig 4. Fibre tear at different temperatures diblocks or triblocks. faster speeds. The HMA is expect - ɀ OBCs are produced with chain ed to hold the package even after shuttling technology and have a a short set time. multiblock structure of alternating By using XUS 38614.00 an hard and soft blocks with a molec - Experimental Polyolefin Plastomer ular weight distribution (Mw/Mn (0.887g/cc with 1000 MI) material 2). Examples from Dow are from Dow with a slightly higher ≈ Infuse OBC and Intune OBC ( fig - density and crystallinity compared ure 2 ). to Affinity GA 1900 (0.870 g/cc Last but not least, among the with 1000 MI) the HMA formula - material types are propylene-eth - tion will have additional strength at ylene random copolymers, mar - a shorter set time ( figure 5 ) – thus keted by Dow under the brand facilitating a fast bond formation. name of Versify Plastomer and ɀ Hard-to-bond surfaces Elastomer ( figure 3 ). Either because of a focus on shelf attractiveness or to achieve cer - A DIFFERENTIATED tain barrier properties, it has been APPROACH TO ADDRESS challenging to ensure adherence Fig 5. Fibre tear vs set time DIVERSE PACKAGING of some substrates to the boards, TRENDS known as ‘hard-to-bond’ surfaces. Among key trends driving the devel - Typical examples of hard-to-bond opment of adhesives for the packag - surfaces are PET, BOPP or coated ing segments are the following: Kraft papers. ɀ High to low temperature adhe - In order to improve the adhe -

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HOTMELT TECHNOLOGY

Table 1. Fibre tear on different substrates measured at a different temperature

Odour Rating 0 = no odour, 5 = very strong odour

Fig 6. Odour rating of PO-based HMA vs SBC-based HMA Fig 7. Above right: Colour and ageing of OBC-based HMA vs SBC-based HMA

sion performance, Dow has devel - elastomers offer improved colour oped MAH functionalised ethyl - and viscosity stability ( figure 7 ). ene-octene : Affinity GA 1000R. This material will pro - DOW WORKS WITH CUS - vide additional strength to differ - TOMERS TO PROVIDE A ent substrates which are ‘hard-to- STRONG RESPONSE TO bond’ due to the polar groups MARKET NEEDS (Table 1 ). As has been seen, brand owners and adhesives formulators are KEY HYGIENE TRENDS faced with an increasingly complex There are also a number of critical and demanding marketplace. Dow trends affecting the development Elastomers is the ‘go-to’ innovation of HMA for the hygiene segment, partner, delivering high perform - including the need for reliable and ance solutions that provide cus - secure feedstocks. In addition, the tomers with a strong response to demanding customer base is look - their needs. The broad range of ing for solutions that deliver: Dow’s POE solutions combines ɀ Low odour performance criteria with cost effi - Customers want high quality ciency and sustainability, thus cre - materials that avoid unpleasant ating a sustainable difference odours. When POE-based adhe - across the value chain. sives are used with the same tack - ifier as SBC, they provide better odour characteristics ( figure 6 ). ɀ Colour and ageing AFFINITY, INSITE, INFUSE, INTUNE, The market increasingly demands VERSIFY are Trademarks of The Dow solutions that deliver improved Chemical Company (‘Dow’) or an colour and viscosity stability over affiliated company of Dow time. -based polyolefin

36 EAS – December 2014 www.coatingsgroup.com