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Outdoor signs come in a variety of materials. Some of the more common materials used in the fabrication of signs are wood and metal. Unfortunately, there are many problems associated with these materials. Painted wooden signs deteriorate quickly in outdoor environments. Paint becomes washed out or discolored while the wood absorbs water and starts to swell, crack and eventually rot. Metal signs rust, become disfigured, or are soon covered with graffiti. This makes it necessary to replace these signs fairly often, causing unnecessary ongoing expenses.
Other sign materials include natural stones such as granite and masonry products such as brick, stone and stucco. Although these materials last a very long time and are very appealing, they are prohibitively expensive.
Two-color HDPE sign board is quickly becoming the solution to these problems with other materials. The material has A-B-A color layers with a different color in the middle than on the skin. The skin of the material is routed or engraved to produce the desired graphic or sign. The material is UV stabilized to resist harsh outdoor environments and does not have to be painted because the color is embedded into the sheet. The material usually has a durable textured finish to resist scratches and marring. Most pens, paints and markers are easily wiped off the surface using ordinary household cleaners.
The thickness of the material varies between 1/2-inch, 3/4-inch or 1-inch depending upon the application. For small signs, 1/2-inch is thick enough, while larger signs may require 3/4-inch or 1-inch thickness to appear visually pleasing. Thinner sheets may be available depending upon the manufacturer. Either one side or both sides can be engraved depending upon the application of the sign. Double-sided signs can have either the same or different graphics on each side. Although many other types of plastic materials are available for use in outdoor signage, HDPE sign board is one of the only plastic materials that is substantial enough to compete with wood, metal, granite and masonry outdoor signs.
This article was written by Ashoo Saigal, Polymer Industries.
|In This Issue:
High density polyethylene sign board
HDPE solves problems brought by wood and metal in the signage industry.
Plastic materials surround you
Layers of opportunity
with high density
About high density polyethylene
Test your knowledge
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Close your eyes for a moment and picture your family’s favorite recreational site. The park with its playground equipment (made of wood, metal or plastic), basketball court (backboards made of polycarbonate), picnic tables (made of wood or recycled plastic) and the small creek with its canoes, paddle boats and waterslide (all made of ABS, HDPE and UHMW). Oh, and on the way, did you see those construction barriers (HDPE) in the parking lot and the signs directing you to the playground? These items were most likely made from that laminated polyethylene.
And did you know that plastic piping systems are being extensively used in recreational attractions and swimming pools? That piping is most likely joined by an IAPD member who manufactures adhesives or welding equipment and utilizes gaskets of polypropylene or PTFE.
Or, imagine it’s winter! You could be a skier and your favorite relaxation is on the slopes. The signs there will also be made of polyethylene. When you were picturing yourself on the mountaintop, did you see all the acrylic/PVC alloy as wainscoting in the lodge to protect the walls?
Your skis, of course, have UHMW bottoms and are likely to be made of fiberglass. Be sure to be looking at the plastic catch netting and the drift preventing fencing when you go up the chair lift, UHMW where you pole up to the chair, RIM cast nylon sheaves for the wire rope, polyurethane or UHMW as bumper and rub strips, fiberglass poles for the racecourse and even polyethylene film to mark closed trails. I bet you didn’t notice, but that shovel had a fiberglass handle and a polyethylene blade.
As you trudge to your room back at the ski lodge, check out the new skating rink they just put in complete with HDPE dashers and acrylic to protect you from the puck just like they do in the NHL. On the way back to the airport, be sure to observe the snowplows — that’s UHMW on the plow-blade and wears strips made of polyurethane.
Now, if you are one for fleeing the snow with the kids and going to the Florida and California theme parks, you will see loads there as well. The signs are here also, but they are made of acrylic, polycarbonate, foam PVC or fluted PE/PP as well as the laminated polyethylene, and a lot of them have vinyl film letters. The barriers for protection are acrylic and polycarbonate, and those for directional purposes are PE or PE film. You don’t notice all the applications, but they are there — like cast nylon wheels on roller coasters with acetal and nylon gears as well as all kinds of UHMW chain guides, and lots of PVC piping and PTFE gaskets again. Come to think of it, the pumps and water fixtures likely have acetal seats and seals. Vinyl tubing is everywhere and that pastry kiosk you’re eyeing has HDPE cutting boards along with acrylic sneeze guards.
Applications for plastics, including HDPE, are everywhere. You just have to open your eyes!
This article was written by James Harrington, CPMR, Engineered Material Sales, Inc.
REPRINTED FROM THE IAPD MAGAZINE
HDPE (high density polyethylene) sheets with multi-colored layers have been making quite a stir in the signage industry — especially when combined with other materials. Innovative sign fabricators are using many materials, including solid HDPE, polymer lettering, epoxies and full-color printed materials under clear acrylic protective covers.
King Plastic Corporation Sales Manager Lou Stegner offers some tips for plastics distributors who want to help their customers explore new signage opportunities with layered plastics and other materials.
Tips when working with HDPE
Fabricators can work with HDPE using standard woodworking tools. Carbide router bits with 2-4 flutes are recommended. With a 1/2'' diameter router bit, feed rates of 12-16 feet per minute are normal. Rates must be slower for material that is 1/2'' thick or thicker. Larger bits have higher tip speeds and RPM adjustments may be necessary. Cuts are made with a circular saw at 1,275 RPM using a 50-70-tooth carbine blade — expect a similar feed rate. Edges may be finished with a router and, if desired, a fine sandpaper. Use standard fasteners with oversized holes. Drill pilot holes first, followed by the oversized hole to allow for expansion and contraction. Make plugs with a wood plug cutter for a finished look.
When creating the sign, the use of adhesives is not recommended, as they don’t adhere well to HDPE. Welding rods made from the same polymer have been used with some success. For raised lettering, some sign fabricators create HDPE letters which are screwed into the sign, then covered with another HDPE letter.
When using printed images, it is best to use a long-lasting material and printing process. Attach an adhesive-friendly substrate with screws, then attach the printed material with adhesive, covering the holes. Use a clear polymer cover for a finished look and extra protection.
Epoxy inlays offer additional options for sign makers. Flame treat the HDPE and drill a series of holes to allow the epoxy to penetrate the HDPE for extra holding power.
This article was written by Rich Odato, King Plastic Corporation.
Rigidity and tensile strength of the HDPE resins are considerably higher than those of the low and medium density materials. Impact strength is slightly lower, as is to be expected in a stiffer material. Values remain high, however, especially at low temperatures, when compared to those of many other thermoplastic materials.
Applications of HDPE range from film products to large, blow molded industrial containers. The largest market area is in blow molded containers for packaging milk, fruit juices, water, detergents and various household and industrial liquid products. Other major uses include signage, high-quality, injection molded housewares, industrial pails, food containers and tote boxes; extruded water and gas distribution pipe, wire insulation and structural-foam housings. (See the property table for HDPE on the IAPD web site at www.iapd.org/new/bookstore/free_resources.html.)
For more information on HDPE and other plastic materials, IAPD’s Introduction to Plastics is an invaluable training manual. Details about it and other IAPD educational resources are available online at www.iapd.org.
What do you know about HDPE? Answers are at www.iapd.org/popquiz.html.
1. Which of the following chemical groups is not compatible with HDPE?
2. Which of the following characteristics would make HDPE a better choice than UHMW-PE in an application?
Your IAPD Distributor is your choice in finding the right material for your application. Go to www.iapd.org to find a distributor in your area. You can search by company name, location or product category.
The IAPD Magazine web site at www.theiapdmagazine.com allows you to search by material, trade name and fabrication process. You can also search for fabrication capabilities.
Designing with Plastics is published by the International Association of Plastics Distribution. While every effort has been made to ensure accuracy, IAPD encourages you to verify information with a plastics distributor to ensure you select the correct plastic products to meet your needs.