Innovative and Flexible Solutions. for High Performance Roofing Felts

Innovative and Flexible Solutions for High Performance Roofing Felts Reaching beyond design and basic functionality, the roofing industry is experie...
Author: Hubert Murphy
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Innovative and Flexible Solutions for High Performance Roofing Felts

Reaching beyond design and basic functionality, the roofing industry is experiencing a great influx in the demand for financial and environmental sustainability. In many parts of the world, roofing requirements are changing due to new government or climate-driven requirements. Additionally, aesthetic and architectural needs continue to evolve, impacting the roofing market and its need for unique, groundbreaking polymer technology. Kraton® styrenic block copolymers (SBCs) for modified bituminous roofing materials have a vast balance of properties, including flexibility over a wide range of temperatures and resistance to thermal degradation. We offer specific technologies designed to exceed the increasing demands for economically sensible roofing materials that meet a variety of criteria and can achieve peak performance over long periods of time.

Unique SBS Grades That Reduce the Tendency to Gel Gelation tendency of standard Kraton grades in B180 bitumen blends (12% polymer content, T 200 °C) 3.5 3

D1184

2.5

Torque, Ncm

In less than optimal situations, or during equipment breakdowns, compounds must be kept at high temperatures over longer periods of time. When this happens, and depending on the quality of bitumen, gelation may become noticeable, leading to a gradual viscosity increase. Kraton® D1184 is a unique styrene-butadiene-styrene (SBS) grade that decreases this propensity to gel, offering more security and manufacturing flexibility, among many other significant advantages.

Competitive Radial Polymer 2 1.5 1 0.5 0 0

10

20

30

Gelation tendency time, hours

40

50

Specific Technologies To Meet Roofing Challenges

Building Better Self-Adhesive Technology

T-peel 21°C [N/25 mm]

T-peel 4°C, instantaneous [N/25 mm]

T-peel 4°C, after 1 h [N/25 mm]

31

21

34

adhesion properties, a low modulus is needed, which poses a manufacturing

B160/220+7% softening oil + 5% KD1184 + 8.5% high vinyl SBS + 15% filler

challenge. Additionally, roofing felts should have a good flow resistance at

200 pen +12% special SIS

102

140*

-

Standard: B160/220+7% softening oil + 5% KD1184 + 8.5% KD-1118 + 15% filler

21

14

14

While self-adhesive roofing felts are a safer alternative to traditional mopping and torching applications, they require polymer formulas that have conflicting requirements. For example, to produce roofing felts with excellent tack and

high temperatures. Luckily, these conflicting needs are easy to meet when we replace SBS grades with styrene-isoprene-styrene (SIS) grades. With the use of an SIS grade, tack and adhesion properties are noticeably improved. Kraton has developed formulas with blends of SBS and SIS - Kraton® D1161, D1163, D1111 and D1119, which include the addition of extra ingredients such as

* Adhesive strength larger than cohesive strength, carrier pulled off from the PMB

naphthenic oil and tackifying resins. Kraton currently offers two of these alternative technologies. One is a fully SBS-based solution with a combination of SBS grades that have a higher vinyl content in the mid-block, making the tack and adhesion performance of this solution less than a SIS-based solution, but still sufficient and with a distinct cost advantage. The second option is a single SIS-based solution leveraging a new grade, Kraton® HT1200, which has a sufficient compound flow resistance and provides simplified processing by using only one polymer without additional additives.

Optimal Solutions for Challenging Climates Tropical and desert climates are among the most challenging for roofing. Kraton premium SBS modified felts provide a high flow resistance, which is crucial for roofing felts in hot climates. Coupled with this high flow resistance, is a cold bend flexibility down to -25 °Celsius, which is unnecessary in these particular environments. Kraton developed a high molecular weight polymer, Kraton® D1191, which provides sufficient flow resistance at lower concentrations. It also provides an economically attractive alternative, while still delivering the high elasticity necessary to withstand repeated movement of the roof structure.

B160/220 + 8% KD1191

Softening R&B [°C]

DIN flow [°C]

Cold Bend [°C]

109

80

-10

Achieving Weight Reduction in Modified Felts There is a growing market demand to reduce the overall weight of roofing felts. This can be achieved by creating thin layers of polymeric single-ply roofing membranes. By increasing the polymer content, the puncture resistance of the thinner felts can be improved. In order to reduce the thickness by 50 percent, 20 to 24 percent of polymer must be added to the formula to retain the puncture resistance. In doing so, manufacturers produce a high quality, low-weight felt, while reducing the amount of bitumen used. Our research has demonstrated that thin felts with high puncture resistance can be obtained by using special polymers designed for use at high concentrations without any processing issues. These studies have shown that the higher the polymer concentration, the smaller the dependence of the compound on the base bitumen quality. As an example, with a grade as hard as 40/50 pen, an excellent felt may be produced which can bridge the gap between standard modified felts and the full polymeric membranes.

Softening point [°C]

DIN flow [°C]

Cold Bend [°C]

Penetration @50°C

138

135

-40

48

158.5

150

-12

65

B50/70 + 20% special SBS Formulation with 30% APP

Lower Compound Viscosity Combined with Superior Performance Achieving a lower compound viscosity while retaining premium performance is important as it paves the way for cost efficiency and higher productivity. In order to obtain this balance, blends are made of radial and lower molecular weight linear polymers. Consequently, intermediate viscosity is attained, along with flow resistance in between the single polymer solutions. Kraton has introduced a unique grade of special molecular design, Kraton® D1189, which offers the performance properties close to those of a full radial polymer modified felt, but with a viscosity of the radial/linear polymer blend.

B160/220 + 12% D1184

B160/220 + 9% D1184 + 3% D1101

B160/220 + 12% D1189

T R&B, °C

128

123

127

Pen at 25 °C, dmm

45

50

50

2100

1600

1600

Cold Bend, °C

-40

-40

-40

Flow Resistance, °C

100

90

100

Service Temp. range, °C

140

130

140

Viscosity at 180°C, mPa.s

Footprinting: Key Differences Between APP and SBS Modified Bitumen When felts are applied, workers walking on the hot surfaces leave footprints. A roofing felt’s “footprinting resistance” has traditionally been assessed by the pen value at 50 °Celsius; the lower the value the better the resistance. Additionally, the hardness of the bitumen and its filler content also affects the initial indentation. Atactic Polypropylene (APP) modified bitumen demonstrates lower pen values, giving the perception of better performance. However, an elastic compound like SBS has a higher initial indentation, but it exhibits a lower indentation at longer time intervals. With this better recovery, SBS modified roofing felts can present a better solution. In the graph shown, the effect of indentation at 76 kilopascals (kPa), which is approximately twice the stress one average-weight person exerting pressure with one foot, is shown at the onset and after recovery. It confirms the relatively low initial indentation for APP based compounds, but also the lower permanent deformation after recovery for SBS modified systems.

A Viable and Cost Effective Alternative to Oxidized Bitumen Kraton has developed formulas that offer a full performance equivalent to oxidized bitumen on the basis of paving grade bitumen, low SBS content, and other additives that can compete on an economical base with current oxidized bitumen grades.

Indentation at 50 °C, 0.1 millimetre

10

0 seconds 15 seconds 30 seconds 45 seconds 90 seconds 180 seconds 300 seconds

9 8 7 6 5 4 3 2 1 0 B45 + 12% SBS

B180 + 12% SBS APP Compound 1 APP Compound 2

Company Profile Kraton Performance Polymers, Inc. is a leading global producer of engineered polymers used to enhance the performance of products that touch virtually every aspect of our lives. As the original inventor of styrenic block copolymer (SBC) chemistry, Kraton has a robust history of innovation that dates back more than 50 years. Used in a myriad of applications, Kraton adds utility, value and customer appeal to products ranging from adhesives and coatings, paving and roofing to personal care items, medical supplies, electronic and automotive components. Kraton offers approximately 800 products to more than 700 customers in over 60 countries worldwide. Dedicated to “Giving Innovators Their Edge,” we also collaborate with manufacturers on custom solutions for specific needs.

Global Distribution Global Headquarters Innovation Center Manufacturing Facility Technical Service Customer Service

U.S.A. Headquarters

Asia Pacific

Europe, Middle East, Africa

India

South America

Houston, Texas +1-800-4-KRATON (572866)

Shanghai, China +86 21 2082 3888

Amsterdam, The Netherlands +31 (0)20 201 7697

Mumbai, India +91 22 4238 9290

Paulinia, Brazil +55 19 3874 7270

For more information, please visit our website at www.kraton.com or email [email protected] Kraton Performance Polymers, Inc. believes the information set forth herein to be true and accurate, but any recommendations, presentations, statements or suggestions that may be made are without any warranty or guarantee whatsoever, and shall establish no legal duty on the part of any Kraton Polymers affiliated entity. The legal responsibilities of any Kraton Polymers affiliate with respect to the products described herein are limited to those set forth in Kraton’s conditions of sale or any effective sales contract. Kraton does not warrant that the products described herein are suitable for any particular uses, including, without limitation, use in the oilfield industry. Persons using the products must rely on their own independent technical and legal judgment, and must conduct their own studies, registrations, and other related activities, to establish the safety and efficacy of their end products incorporating any Kraton products for any application. Nothing set forth herein shall be construed as a recommendation to use any Kraton product in any specific application or in conflict with any existing patent rights. Kraton reserves the right to withdraw any product from commercial availability and to make any changes to any existing commercial or developmental polymer. Kraton expressly disclaims, on behalf of all Kraton affiliates, any and all liability for any damages or injuries arising out of any activities relating to the use of any information set forth in this publication, or the use of any Kraton products. This publication includes “forward-looking statements,” which are statements other than statements of historical fact and are often characterized by the use of words such as “believes,” “expects,” “estimates,” “projects,” “may,” “will,” “intends,” “plans” or “anticipates,” or by discussions of strategy, plans or intentions. All forward-looking statements in this publication are made based on management’s current expectations and estimates, which involve risks, uncertainties and other factors that could cause results to differ materially from those expressed in forward-looking statements. These risks and uncertainties are more fully described in “Part I. Item 1A. Risk Factors” contained in our Annual Report on 10-K, as filed with the Securities and Exchange Commission and as subsequently updated in our Quarterly Reports on Form 10-Q. We hereby make reference to all such filings for all purposes. Readers are cautioned not to place undue reliance on forward-looking statements. We assume no obligation to update such information. Kraton, the Kraton logo and design, the Cariflex logo, Cariflex, Nexar and the Giving Innovators Their Edge tagline and, in some cases, their expression in other languages, are trademarks of Kraton Performance Polymers, Inc. and are registered in many countries throughout the world. © 2015 Kraton Performance Polymers, Inc. All rights reserved.