oof consultants should know production of the underlayment. ASPHALT-SATURATED ORGANIC their materials inside and out. There are many similarities among tra- The manufacture of asphalt-saturated To fully understand under- ditional, specialty, and synthetic under- felt begins with the delivery of dry organic layment, one must have a layment products. Here we compare anal- felt to the factory. This material is made basic understanding of raw ogous manufacturing processes for tradi- out of cellulose obtained from post- materials and manufacturing. tional asphalt-coated and premium consumer and post-industrial waste such RSubtle variations at the molecular level have modified-bitumen membranes, as well as as newspapers, cardboard, and wood. The large effects on the properties of materials; synthetics. cellulose fibers are reduced to a water-based furthermore, variations on the macroscopic An underlayment company should be pulp, formed into sheets, dried, cut into scale also affect performance. Ideally, the intimately involved with the manufactur- strips, and wound onto rolls. Being made manufacturer of the roofing underlayment ing processes. Manufacturing facilities that from 100% post-consumer recycled materi- is knowledgeable of engineered polymers, are dedicated to the production of roofing al, dry organic felt mat is an eco-friendly or and its technical staff can work with poly- underlayment can be continually improved “green” material. mer producers to optimize the formulas for as more is learned from the end-users. The dry felt is delivered to the plant by polymers that are blended for use in the truck and stored on-site. Meanwhile, hot asphalt is delivered by tanker truck (Figure 1) and pumped into one of several asphalt storage tanks. The asphalt is kept hot by electric and natural gas-fired heaters locat- ed at the asphalt storage tanks. The liquid asphalt circulates in a loop through the sat- urator and back to the asphalt tanks. The asphalt temperature is carefully controlled at all times. Rolls of dry felt are loaded onto the unwind stand (Figure 2) and unrolled through the dry looper section (Figure 3). The dry looper consists of a series of rollers, pulled along by a chain, which is used to form loops, maintain tension on the paper, and allow product accumulation. From the dry looper, the dry felt enters the saturator (Figure 4). The saturator consists of a series of rollers, commonly referred to as “gates.” The bottom rollers of these gates are submerged in hot asphalt, maintained usually at a temperature of Figure 1 – Asphalt unloading. 350°F (177°C). The gates can be raised or

8 • I NTERFACE O CTOBER 2 0 1 6 Figure 2 – Unwind stand.

Figure 3 – Dry looper.

lowered to change the level of saturation of • Type of dry felt, the asphalt into the felt paper. whether soft or The saturation level is expressed as a hard percentage, ranging between no absorp- • Temperature of tion (0%) and fully saturated (100%). It the asphalt describes the extent to which the felt, upon • “Dwell time,” being immersed in hot asphalt, absorbs and or the period of adsorbs the asphalt and retains it under the time that dry felt Envirospec Ad 262-0801 1/21/08 9:03 AM Pa processing conditions. The type of asphalt resides in the used is called “saturant asphalt.” The sat- saturator uration level has a direct correlation to the • Speed of the production line finished product weight; the greater the saturation, the higher the weight. After the felt is saturated, it passes over Saturation level depends on various fac- a series of three to five scraper blades to tors, such as: remove excess asphalt. The second blade

Figure 4 – Saturator.

O CTOBER 2 0 1 6 I NTERFACE • 9 Figure 6 – Winder.

Figure 5 – Finish looper.

MODIFIED- mixing tanks have a capacity of 25,000 BITUMEN ROOFING lbs., which is approximately 3,000 gallons Modified bitu- (Figure 8). Asphalt is heated to approx- minous self-adher- imately 400°F (204°C), and the various ing underlayments polymers are added into the tank. The exact are made of bitumen quantities depend on the specific product compounds such as formulation. can be adjusted in or out to increase or asphalt that have Mix tanks are equipped with agitators decrease the amount of asphalt removed been modified with polymers to be more or blades that keep the asphalt and poly- from the surface of the paper. The saturator rubber-like and easier to handle. A tough mers in circulation at high speeds. The is totally enclosed; asphalt vapors from the fiberglass mat gives strength against rips blending process takes from two hours up process are routed to the scrubber/cooler and tears and makes it easy to handle the to six hours, depending upon the quan- (for cooling) and to the -bed filter mist modified-bitumen material. The fiberglass tity and type of polymers, as well as the eliminator for control of emissions. mats used in roofing are made of chopped equipment specifications. During this pro- The asphalt-saturated felt enters the strands of fiberglass. cess, the polymers break down and bond cooling section (also known as “the black The manufacture of polymer-modified with asphalt, resulting in a homogeneous rack” or the “striking section”), where it bituminous specialty underlayment prod- asphalt-polymer network or matrix. Other is drawn over several rollers and allowed ucts consists of several distinct steps: ingredients such as oil and tackifying resins to cool in ambient conditions. The cooling • Mixing and filler addition are added as needed. Filler materials such section is also enclosed, and the vapors are • Saturating and coating the rein- as limestone or talc are added into the mix routed to the scrubber/cooler and then to forcement the mist eliminator for emissions control. • Surfacing From the cooling section, the saturated • Cooling felt rolls onto the finish looper, which is • Cutting and another series of rollers that forms the winding (into saturated felt into hanging loops (Figure 5). roll form) The asphalt-saturated felt is pulled into the winder, where the rolls are formed and cut Mixing and Filler into varying lengths (Figure 6). Addition At this stage, “ply marks” or “laying Asphalt is blended lines” can be printed on the surface of the with polymeric addi- felts. They are typically marked at 2, 8½, tives such as atactic 11¼, 17, 19, 24¾, 27½, and 34 in. polypropylene (APP), The roll is pushed along a conveyor, styrene butadiene where it is wrapped with a paper label and styrene (SBS), poly- stacked vertically on pallets. When a pallet ethylene (PE), and is full, it is automatically banded and stored other chemicals in in the warehouse, ready for shipment. mixing tanks or ves- sels (Figure 7). Typical Figure 7 – Polymer additives.

1 0 • I NTERFACE O CTOBER 2 0 1 6 tank and allowed to blend, usually for one hour or so. In some cases, the polymer- modified asphalt blend is transferred to a holding tank before being transferred to the production line.

Saturating and Coating the Reinforcement From the mix tank or holding tank, the modified-asphalt blend is transferred to the coater in the production line. From the unwind stand located at one end of the production line, the reinforcement (also known as carrier or mat)—such as dry felt, glass mat, or —is unwound from master rolls. The coater section typically consists of a rectangular tank and a series of rollers. When the reinforcement enters the coater, it is saturated with the modified-asphalt blend. Simultaneously, the modified-asphalt coating is applied to the upper and lower surfaces of the saturated reinforcement. Figure 8 – Mix tanks. The level of saturation again is greatly dependent upon several factors. In this • Run speed • Temperature of the modified-asphalt case, the factors include the following: • Type of modified-bitumen compound blend • Dwell time of the reinforcement in • Viscosity of the modified-bitumen • Type of reinforcement the coater compound

7.50W X 5H.indd 1 1/12/16 5:06 PM O CTOBER 2 0 1 6 I NTERFACE • 1 1 Also present at the coater section are Cooling metering rollers, which are employed to The sheet is achieve the desired product thickness by con- then fed through trolling the amount of modified-asphalt blend water-cooled drums applied on either side of the reinforcement. to allow it to cool rapidly (Figure 10). Surfacing In some cases, Once the saturated and coated rein- the sheet trav- forcement exits the coater section, the els through a necessary surfacing material is applied. chilled water bath. Surfacing materials are added for various Alternatively, water reasons. For example, sand, talc, or liquid spray may be used parting agent (LPA) is applied to the upper to cool the sheet. surface of the product to keep the material Some manufac- from sticking within itself when wound into turing lines are roll form. Silicone-coated release film is equipped with applied to the self-adhesive compound on dryers to air-dry the bottom side to prevent roll sticking and the sheets. After Figure 9 – Release film application. to maintain the adhesive characteristics of cooling, the sheet the finished product Figure( 9). enters the accumulator section, which con- THE MANUFACTURE OF SYNTHETICS Alternatively, polymeric film or fab- sists of a series of rollers that allow the Producing synthetic underlayment from ric materials are applied to the topside, material to form into loops. polypropylene (PP) pellets is a marvel of depending on the product configuration and modern manufacturing. The process can end use. In the case of mineral-surfaced Cutting and Winding be subdivided into several distinct stages membranes or underlayments, mineral or From the finished product looper at the as follows: ceramic granules are applied to the topside accumulator section, the sheet travels to • Spinning the fibers or filaments of the finished product. However, nongran- the winder, where it is cut to the required • the PP filaments into scrim ulated sheets bypass this step. lengths and wound into roll form (Figure • Extrusion-coating on scrim Depending upon the type of surfacing, 11). The finished rolls are labeled or taped • Extruding PP various auxiliary equipment and devices for product identification, and paper tubes • Bonding various layers together to are utilized in the production line. For or cores are inserted into the inner diameter form the synthetic felt example, during the production of a fabric- of the rolls to provide stability during stor- • Printing, cutting, and packing into surfaced underlayment, a fabric applicator age and shipment. The rolls are stacked on individual rolls is employed. pallets, secured using stretch film or shrink bags, and stored in the warehouse prior to Let’s take a closer look at the manu- shipment to cus- facturing equipment used at each stage, tomer locations. from the point where the plastic pellets are extruded to the point where the components are finally assembled together into synthetic underlayments and packaged for the roofing marketplace.

Figure 10 – Cooling section.

Figure 11 – Winder.

1 2 • I NTERFACE O CTOBER 2 0 1 6 THERE ’S ONL Y ONE WAY TO MEASURE THE TRUE PERFORMANCE OF A ROOFING MEMBRANE PRODUCT ...

TIME

There is no substitution for experience. Trust the original KEE solution

www.FiberTite.com/KEE FiberTite is manufactured exclusively in the USA by Seaman Corporation. For information, call 800-927-8578. since 1979 Figure 12 – Mixer. hopper, which then follows to the extruder hopper. The extruder hopper allows the raw materials to enter the feed section of the extruder (Figure 13) in a continuous fash- ion, by gravity. The feed section is con- Figure 13 – Extruder hopper. nected with the pipes to the water supply system for flow and return of chilled water. The cooling system eliminates slippage of the raw materials as they are pumped in the direction of a series of drums towards the die. Raw materials are continuously fed at a rate proportional to the speed of the extrud- er screw. The temperatures at each of the heating zones are maintained to assure proper mixing, melting, and conveying of material. The extruder screw plasticizes the granules into melt form and conveys it for- propylene sheet into many strips, ward. At the exit end of the extruder screw, which are further processed into a screen pack consisting of varying threads or filaments. sizes screens out the unmelted particles. An appreciation of the manufacturing The primary raw material employed in The polymer melt must be filtered to ensure processes will make it easier to understand the manufacture of PP filaments or fibers there are no bubbles or contaminants. the slight differences between product offer- is PP granules, which can also be referred Ideally, the polymer melt will have a consis- ings, including the features and benefits to as “pellets.” Depending on the color tent chemical composition and, hence, also of different products from the same man- requirement of the final product, color pig- predictable physical properties. The lengths ufacturer. For polymer-based fabrics, it is ment is incorporated into the master batch. of molecules within the polymer melt will a maxim that the “figure of merit” is tear Furthermore, depending on the end use and not vary greatly such that the viscosity, resistance divided by weight. The use of expected outdoor exposure of the finished melt flow characteristics, and melting tem- woven polymers in synthetic underlayments product, ultraviolet stabilizers (UV addi- peratures do not vary over the length of the greatly increases their tear resistance and tives) are included in the master batch. The filaments (or “strips,” “threads,” or “tapes”). imparts other properties, as well. It has various ingredients are blended at precise The polymer emerging from the slot die been found that a woven scrim with widely formulations at the mixer (Figure 12) and is chilled to a solid form at a water tank, and spaced fibers combined with flat, nonwoven then conveyed through a suction pipe to the the chilled film passes through two pairs (extruded) polymer sheets provides high tear resistance.

Producing Filaments The industry has been mak- ing fabrics from polymers for more than 50 years; as a result, the processes and equipment are highly evolved. A fiber of continuous length is typically referred to as a “filament.” With modern equipment, it is possible to convert a thousand pounds of polymers into filaments without a single break occurring. In the textile industry, molten polypropylene passes through an adapter into a die that has a pattern of holes in it. The liquid polymer being forced through these holes solidifies in a short distance—typically about 100 centimeters or 40 inches (one meter)—and it can be further stretched or treated before winding onto spindles. In the manufacture of synthetic under- layment, the threads used to manufacture scrim are made by slitting an extruded poly- Figure 14 – Film slit into filaments.

1 4 • I NTERFACE O CTOBER 2 0 1 6 Figure 15 – Winding filaments into spools.

Figure 16 – Quality control equipment.

of scrapers on the way to the squeeze-off rollers, where the remaining drops of water are removed. Then the film enters a slitter where a spreader roller straightens any wrinkles in the film, and slitting blades cut the film into fibers or filamentFigure ( 14). The width of individual fibers is adjusted by using spac- ers of suitable size in between the slitting blades. A system of godets is used to draw the filaments. (In the textile industry, a “godet” is a roller for guiding synthetic filaments during drawing. It is derived from a French one that might be used to weave a stock- “weave.”) The warp weave is in the machine word for a “cup” or a Dutch word for a ing hat or a sweater arm. Such weaving direction; the weft weave is in the cross- “cylindrical piece of wood.”) Filaments from processes are demonstrated on YouTube machine direction. The number of tapes in a first godet station pass through a hot videos, which can be found by searching one inch in warp direction is known as warp air oven and enter a second godet station, for “circular loom.” The main difference is mesh (X). These tapes are passed through a which is maintained at ambient tempera- the high-speed operation of a large circular series of inline process equipment for reed ture. The speed of this second godet is four loom. weaving on the circular loom. Technically to five times higher than the speed of the Dozens of spools of filament are fed speaking, the equipment includes eyelets, first godet. (The speed corresponds to draw into an automated circular weaving loom, a roller, intake combs, a water-tank-chilled ratio, which is chosen according to the prop- including both the “woof” and “weft” fila- roller, eyelet bows, compensators, heddle erties of the raw material and the expected ments (Figure 17). The filaments are woven belts, and reed rings of suitable dent. quality of the fibers.) The filaments then into scrims at the circular loom (Figure 18). (See any good textile-industry glossary for enter a third godet station, which is main- Miles of woven tained cold using a chilled water circulating fabric are pro- system, thereby freezing the molecules and duced by each aligning them in an oriented state. loom; and typ- Such oriented filaments possess high ically, many tensile strength and other desirable phys- looms run in ical characteristics. Ultimately, these parallel at the threads are gathered into spindles and same factory. wound onto spools (Figure 15). The spools The close- will in turn feed the weaving machines. ness of weave is Various properties of the filaments can be represented by inspected to maintain quality control before mesh in terms of the spools are sent to the next processing X by Y, where “X” step (Figure 16). represents the warp mesh, and Weaving the Scrim “Y” represents Just as spinning polymers into fila- the weft mesh. ments involves highly evolved equipment, (The “mesh” is so, too, does the weaving of the filaments also known as into scrim. The weaving pattern resembles the “count” or Figure 17 – Thread to weaving.

O CTOBER 2 0 1 6 I NTERFACE • 1 5 Figure 18 – Circular loom.

Figure 19 – Winding scrim into rolls.

definitions of these terms.) In this manner, the loom is thread- ed to define the weave in warp direction. The weft filaments are woven through the weave filaments in the circular loom. Finally, the woven scrim is wound into rolls of suitable width and length (Figure 19).

Extrusion Coating on Woven Scrim Extrusion coating is the process of coating a polymeric resin on a woven scrim substrate by extruding a thin film of molten resin and pressing it onto or into the woven scrim substrate or both, with or without the use of adhesives. This process of extrusion coating on woven scrim is conducted on an extrusion-coating machine. The basic raw material for coating the is polyolefin. Other raw materials used are the color master batch, UV master batch, and so on. The blended raw materials are fed to the extruder hopper. The woven scrim in suitable roll form is loaded onto an unwind stand and guided through the rollers to the die. The molten material from the die is extruded onto the woven scrim surface in film form. The molten film laminated to the woven scrim is passed under heavy pressure through rubber rolls and a chilled roll, and eventually, it is wound into roll form at the winder. Thus, one side of the coating process is completed. The one-side coated roll is once again loaded onto the unwind stand, and the other side is coated in the same manner. The excess material (overhang) is trimmed off the edges, and the final product is wound in roll form at the winder.

Extruded Nonwoven Fabrics Meanwhile, in another part of the factory, the sheets of nonwoven polypropyl- ene are also extruded. Blown extrusion is com- monly used in the man- ufacture of trash bags and shopping bags; in the case of blown extru- sion, a tube of melt- Figure 21 – Nonwoven fabric ed polymer is expand- roll ready for lamination. ed with air pressure. However, the nonwoven sheets used for synthetic Figure 20 – Woven scrim ready for lamination.

1 6 • I NTERFACE O CTOBER 2 0 1 6 felts are too thick to be blown. Instead, the resistance and imparts other properties, (Figure 21). The woven scrim and the non- polymer melt is forced through a die that as well. Once the woven and nonwoven woven fabric are sandwiched together at the has a thin rectangular hole for an exit. components are ready, they need to be pressure roller. It is important to set the The dies must guide the polymer melt bonded together. Typically, synthetic under- suitable temperature, pressure, and tension from the circular outlet of the extrud- layments are composed of two layers, with in order to eliminate the possibility of film er screw to a thin, flat planar flow. This the nonwoven fabric as the top layer and the burn-through or deformation in the mesh flow must be uniform across the entire woven scrim as the bottom layer. surface. However, the process parameters cross-sectional area of the die. The sheets From the unwind stand at the coating must be adjusted so as to achieve the target may then be passed between additional machine, the master roll of woven scrim is bonding strength. In addition, coatings can rolls for cooling and to establish the desired unwound and guided through a series of be added on either surface of the material sheet thickness and surface texture. At this drums (Figure 20). From another unwind (Figure 22). The resulting laminate then stage, the surface of the extruded sheets stand, the nonwoven fabric is unwound follows a series of chilled rollers to the wind- could be enhanced in such a way to allow and guided through a series of guide rollers er, where any excess overhang is trimmed for improved walkability of the finished product. It is a simple matter to transfer an emboss pattern from a preformed mechan- ical roll to the sheet shortly after it comes out of the die and before it has fully cooled. Colored dyes are best added at this stage. While it is possible to print on polypropylene sheets after they have been extruded, polypropylene cannot be dyed after it has been extruded in the sense of in an aqueous bath as is done with other . Of course, that is because the very properties that make polypropylene a good (water-resistant) roofing underlayment also make it impossible to dye. Nonetheless, vivid colors can be obtained by adding the dyes to the melt before the sheets are extruded.

Bonding the Layers Together A synthetic underlayment really has a multilayer configuration. As mentioned ear- lier, the use of woven polymers in synthetic underlayments greatly increases their tear

Figure 22 – Application of surface coating.

BLC923 Thermally Broken RH Ad_INT.indd 1 2/18/15 3:58 PM O CTOBER 2 0 1 6 I NTERFACE • 1 7 off from the sides, Figure 23 – Ready for and the material is winding at winder. slit to the desired Figure 24 – Printer. lengths and wound into roll form (Figure 23). The under- layment materi- al is then stored in the form of master rolls. The master roll is a space-saving me- thod for storing synthetic underlayment, Figure 25 – Winding into small rolls. but not a very efficient way to bring it to market. Now it is easy to understand how the Printing and Packaging final product features are obtained by start- in Roll Form ing with various sheets or scrims and pro- Printing is typically cessing them further with asphalt or poly- done at this final stage. mer coatings. It is also easy to understand The material is printed how these features relate to the practical with the necessary art- considerations of the roofing contractor. work at the printing press A thorough knowledge of the underlay- (Figure 24). Standard ment manufacturing process is useful for products include mark- understanding specific product features of ings to show where to various types of underlayment; how they apply fasteners and also can be modified to match the underlayment product name and other to the application; and how the perfor- useful information. The logo of the end-user For conventional felts, the original shape mance, ease of handling, walkability, and could also be printed on the synthetic of the sheet is obtained by heating and com- other features can be improved. underlayment at this stage. pressing the nonwoven organic felt material. The final step of the manufacturing This material is then saturated with asphalt For specific examples of the properties of process involves packaging the synthetic to impart water resistance. underlayment products with reference to the felts into lightweight rolls that can be easily For specialty underlayment, the mat is, above manufacturing processes, read the handled by the roofing contractor. Synthetic in many cases, a woven or nonwoven poly- complete white paper, entitled “Rethinking roofing underlayments are thinner and mer that is sandwiched between layers of Roofing Underlayments,” available from lighter than conventional asphalt-saturated modified-bitumen material. Tarco at www.tarcoroofing.com. roofing felts. Consequently, it is possible to package them in rolls that can cover a total area of ten squares rather than one Steve Ratcliff Shaik Mohseen or two squares, and yet the roll will still be joined Tarco in joined Tarco in light enough to be handled by one person. 2001 and was 2006 and was Making the rolls wider also results in labor promoted to pres- promoted to savings, since the roofer can cover twice the ident and CEO in chief operating area with the same sheet length if the sheet 2003. He previous- officer in 2010. is twice as wide. ly held positions at He previously At the rewinder, the master rolls are Justin Industries, held positions unwound and cut to desired lengths and Allied Chemical at Nord Bitumi then wound into roll form onto plastic or Corporation, U.S., Dibiten USA, paper cores (Figure 25). George K. Baum Johns Manville, Steve Ratcliff & Company, and Shaik Mohseen and Poly-glass. SUMMARY AND CONCLUSION Honeywell. Steve Mohseen earned a All of these manufacturing processes built a roofing system business with a nation- bachelor’s degree in engineering from the involve rollers for moving sheets of material al identity in the 1990s. He holds an under- University of , Madras, India; an through various processes. Thicknesses, graduate degree in marketing from Henderson MS degree in materials science and engi- temperatures, and material properties must State University and an MBA from the Duke neering from the University of Florida; be tightly controlled. University Fuqua School of Business. and an MBA from Texas State University.

1 8 • I NTERFACE O CTOBER 2 0 1 6