Understanding Architectural Panel Tapes

Architectural panel tapes (APT) are high performance double-coated acrylic foam tapes designed to replace rivets, welds, liquid adhesive systems, and other mechanical fasteners used in the fabrication of curtain walls, exterior cladding, and interior panel bonding and trim attachment.

The Benefits

The architectural panel tapes bring much more to the table than just replacing mechanical fasteners and liquid adhesives:

  • The viscolelastic properties of the tape absorb shock and flexing for reliable bonds against wind loads, vibrations, and thermal expansion and contraction.
  • The tape fills gaps to seal out water, dirt, and air.
  • The tape is invisible and hidden in the bond line. It doesn’t telegraph through the panel and enhances the appearance and beauty of the panel.
  • Tapes excel at joining dissimilar materials and permit the selection of a wider variety of materials for more stunning results. This includes painted metals, powder coated metals and hard to bond surfaces such as acrylic and polycarbonates.

The Proof is in the Performance

Architectural panel tapes have some formidable physical properties. Most people are stunned when they are given a demonstration part that is put together with APT. They simply can’t get them apart no matter how hard they try but the data is really what tells the story:

Applications

These tapes perform in both exterior and interior applications including:

  • ACM panel bonding
  • Exterior cladding and curtain walls
  • Interior column cladding
  • Stiffener to panel attachment
  • Clip bonding and attachment
  • Mirrored and glass ceiling tile attachment
  • Trim bonding

Want to learn more about APT or get some samples to try? Give Tom Brown, Inc. a call today!


Silicone Rubber Products for High Performance Applications

Silicones are a large family of elastomers with a unique chemical structure that  gives them superior high and low temperature capabilities that are unavailable in other families of elastomeric materials.

Silicones are very inert and, therefore, resist sunlight, ozone, oxidation, water and various chemicals. They contain no acid-producing chemicals and do not initiate corrosion.

Thermal Stability

Silicone’s physical performance properties are not affected by prolonged exposure to low temperatures (100°F), or high temperatures (+500°F), and can even withstand intermittent exposures to higher temperatures. (see Figure A below)

Silicones far outperform other elastomers in general service life, compression set resistance, electrical strength, and non-stick properties. They also exhibit good chemical resistance. Some solvents, such as gasoline or aromatic hydrocarbons, may cause temporary swelling of the polymer. But the material will return to its original dimensions after evaporation.

Variations

Silicones are available in solid rubber, sponge and foam rubber forms with a variety of  durometers. General purpose silicone rubber is extremely versatile and is often the best choice for applications involving high heat and pressures.

Silicones can be modified with fluorinated compounds to improve chemical resistance and phenyl chemistry to drive low temperature performance even lower to -130°F.

Fillers can be added to gain electrical conductivity, thermal conductivity and flame retardant properties. Fiberglass reinforcement can be added to improve dimensional stability.

Figure B below shows the compression-set comparisons for various grades of silicone rubber, sponge and foam.

Adhesive Options

Silicones exhibit low surface energy, which can make them a bit tricky to laminate with adhesives and achieve good anchorage. Tom Brown, Inc. has the know-how to modify the surface to permit lamination with either silicone or acrylic adhesive systems for gasket attachment or general bonding. Silicone pressure-sensitive adhesive exhibit temperature performance similar to that of the silicone elastomer (100°F to +500°F). Acrylic adhesives are a cost-effective option for some applications, but you trade away some of the temperature range. These adhesives will typically work in the -20°F to +350°F range.

Want to know more about silicone elastomers? Contact Tom Brown, Inc. today for samples, technical data, or to discuss your specific application.

(Photos and table courtesy of Saint Gobain Tape Solutions)

Unique Material Combinations- A Case Study

One of the fun things about working with large curtain wall manufacturers is that they are always looking to try new designs and concepts. That can make being a supplier a little bit of fun, too, to say the least. Sometimes you get to try “outside the box” ideas and let your customer see what you have created for them.  This is one of those stories.


Background

One of our curtain wall customers was designing a system for the new Salt Lake City Airport. In case you didn’t know, the current airport serves 23 million passengers a year in a 50-year-old facility designed for half that amount of traffic. This large project will generate over $3.6 billion in economic impact over the life of the upgrade.


Our customer needed a soft-foam product that could act as a water and air seal.  He really wanted the foam to be skinned with silicone for compatibility with other structural sealants that would be used in an expansion pocket.


The Solution

If you just try to search for silicone-skinned foam using a Google search, you will note a few silicone-foam products with smooth skins designed for other applications. There is no readily available solution. So, our CEO, Kenny Brown, took it upon himself to try something different. From past experience he knew that Saint Gobain produces an excellent low density foam, the V730 series. The V730 has some very useful properties including:

  • Sound transmission and vibration controls
  • ow thermal conductivity improving energy efficiency
  • Excellent seal against dust, light, and moisture
  • Closed cell structure for  a positive seal at 30% compression
  • Low deflection force reducing distortion of any adjacent materials

Next, he took a self-leveling silicone sealant from DowSil and applied approximately 20 mils on top of the ¾” thick V730 foam. He  cut it into blocks using a Waterjet cutting table.


A simple but elegant composite fills the expansion pocket with a high performance water and air seal. And  it is completely compatible with other primary sealants that will be used in constructing the façade. And yes, it looks very much like a gray brownie!

Have an application that requires a unique material solution? Contact Tom Brown, Inc. today to discuss how we can help.

High Performance Polyurethane Foam Tapes

I always feel a little sorry for polyurethane foam tapes. Why? They tend to get lost in the shuffle between the acrylic foam tapes on the one side, and the lower cost polyolefin foam tapes on the other.

Despite this, polyurethane foam tapes have some formidable physical properties and have an excellent performance to cost relationship.

What are Polyurethane Foam Tapes?

Polyurethane foam is produced by reacting polyols with diisocyanates to create highly resilient foams that we use every day in mattresses, car seats, and foam for tapes and gaskets. Various additives are incorporated to help tailor the urethane for particular applications.

These foams are coated acrylic adhesive systems that yield a high performance bonding tape that can:

  • Dissipate energy and stresses along the entire bond line
  • Resist weather, extreme temperatures, UV light, and fungus

One of the premier manufacturers of polyurethane foam tapes is Saint Gobain. They produce an excellent range that includes the V2800, V4600, and V8800 for severe exterior applications, V1300 for interior applications, the V900 series for electronic applications needing a UL rating and the Z500 series for automotive applications.


V2800 Series Physical Properties


Pay particular attention to the high dynamic shear and dynamic tensile values. These high values translate well into bonding tape applications for roof bows and panel stiffeners in truck and utility trailers and RVs,

  Other applications for polyurethane foam tapes include:

  • Body side molding
  • Wheel weight attachment
  • Composite panel bonding
  • Emblems and nameplate attachment
  • Sign framing
  • Wheel well and door edge moldings
  • Bumper trim and inserts
  • Rocker panels

Polyurethane foam bonding tapes might lack the popularity of the acrylic foams and polyolefins, but they perform reliably in heavy duty applications every day. They have an excellent cost benefit balance and should be considered for your next high performance assembly application. Want to know more about polyurethane foam tapes? Contact Tom Brown, Inc. today!

Foam Tapes for Muntin Bar Attachment

Simulated divided lites are a popular design option for residential and even light commercial windows. The design intent is to create the look of individual panes of glass by applying muntin bars or grilles internally (called “G-B-G” for glass/bar/glass) or externally by using foam bonding tapes. Muntin bars attached with high performance tapes having a pleasing visual appearance, have secure bonds if installed correctly, and save production time.

Types of Foam Tapes for Muntin Bar Attachment

The two most common types of foam tape used for bar attachment are acrylics and polyolefins.

Acrylic Tapes

Acrylic foams include the popular VHB brand from 3M and the Norbond brand from Saint Gobain. Other suppliers of high quality acrylic foam tapes include the AS series from Scapa, the ACX series from Tesa, and the SFB series from Avery Dennsion.

These tapes can be monolithic meaning the adhesive and foam core are extruded in simultaneously in a single layer or they can be multi-layer where an extruded acrylic foam core is coated with the acrylic adhesive system. In either case, these tapes exhibit excellent viscoelastic behavior. This means the “viscous” behavior allows the tape to absorb and damp energy that occur from sudden wind gusts or other forces while the elastic behavior allows the tape to recover (think of stretching a rubber band and then letting it come back to its normal shape).

 

Saint Gobain A7300 Series Performance Data

Polyolefin Foam Tapes

Polyolefin foam tapes are made from a foam core extruded from polyethylene that is often modified with varying amounts of EVA and polypropylene. Additional coatings can be extruded onto the foam core to create a very smooth surface onto which the acrylic adhesive will be coated. High quality polyolefin foams are produced by Adhesives Research as well as Berry Plastics, Adhesive Applications, and others.

The polyolefin foams don’t have the same viscoelastic behavior of the acrylic foam tapes but they exhibit very good dynamic shear and tensile (T block) values along with a very favorable price that can make them worth considering especially for lighter weight muntin bars made from cellular PVC and other lightweight materials.

Adhesives Research 8645 Muntin Tape Performance Data

 

Foam Core Stress /Strain Capabilities

The chart below demonstrates the capabilities of each basic type of foam core and how they differ.

 

Want to know more about muntin bar tapes? Contact Tom Brown, Inc. today for samples, technical data, or to discuss your application further.

Understanding the Effect of Coefficient of Thermal Expansion on Tape Products

The coefficient of thermal expansion is used to understand the rate at which a certain material expand as a function of temperature. This understanding is very important when designing adhesive bonded joints to determine if failure by thermal stresses might occur.

Definition

The coefficient of thermal expansion (CTE) is defined as the change in length or volume of a material for a unit change in temperature. The coefficient is reported as the linear thermal expansion in inches or millimeters per degree Fahrenheit or Celsius.


Why is this Important?

One of the major benefits of tape products is their ability to bond dissimilar materials. It is quite common for plastics to have 8-10 times the thermal expansion of metals.

These thermal stresses become important to understand when bonding glass to metals especially in architectural applications where failures can be extremely expensive or even catastrophic.

Design engineers can calculate the joint movement by two equations and determine if the tape system can handle the expansion over the desired temperature range.



Different foam cores have differing abilities to help manage thermal expansion stresses.

Want to know more about how tapes can help manage thermal expansion? Contact Tom Brown, Inc. today.

Die Cut Foam Tape Products for Bonding and Assembly Applications

People don’t realize how often they touch or interact with products that are assembled with die-cut foam tapes. The most common one would be the cell phones most of us use every day but there are our appliances, our cars and trucks, utility trailers, and a host of other gadgets that are put together with die-cut foam bonding tapes.

Why use foam tapes?

It comes down to two words- consistency and reliability. Foam tapes are manufactured to precise specifications in terms of thickness, physical properties, and cut part dimensions. This means that you’re applying the same amount of product every time and that translates to consistency.

By contrast, liquid adhesives have much high variability and mess associated with their application and mechanical fasteners require tools and often the bond lines exhibit point pressure where the fastener is installed. With foam tapes, stresses are uniformly distributed around the perimeter or bond line evenly.

Tapes are viscoelastic and have excellent fatigue resistance. While vibration and joint flexing can compromise mechanical fasteners, tapes dampen vibration and absorb shocks allowing the joint to recover time after time.

Common Types of Foam Bonding Tapes

The most common types of foam tapes are acrylics, polyurethanes, and polyethylenes.

Die cut acrylic and urethane foam tapes provide superior bond strength when applied to a clean, dry surface. They exhibit high dynamic shear values. These values are high enough to make them equivalent to one rivet every four inches. If you’re assembling a side panel onto a utility trailer, you get a smooth appearance without any distortion or splitting.

If you use a urethane foam tape to bond a roof panel onto a roof bow support member, you get a joint with exceptional tensile strength and vibration damping capability that translates into longer trailer life without fear of corrosion due to drilled holes.

Polyethylene foam tapes are less expensive than acrylics and urethanes and are an excellent choice for less demanding applications such as appliances, medical devices, and electronic housings.

Other Benefits of Using Foam Bonding Tapes

Foam tapes allow the joining of dissimilar materials such as metal, plastics, and glass. They also permit lighter, thinner materials to be successfully incorporated into a design. This means that materials that cannot be welded or easily riveted can be considered.

Foam tapes seal and bond in one step. You achieve a strong bond that seals out water, dust, and other contaminants.

Products assembled with die-cut foam tapes have improved appearance and aesthetics. The tape is hidden in the bond line and eliminates the need for pre-drilled holes that can act as a site for corrosion. The absence of holes and welds means no additional clean up steps thus reducing production steps and costs.

Are die-cut foam tapes right for you? Contact Tom Brown, Inc. today to discuss your application!

Understanding Silicone Pressure-Sensitive Tapes

In the two preceding blogs, we discussed the historical importance of rubber based pressure-sensitive adhesives and their continued use in today’s applications as well as the “workhorse” adhesive family- acrylics.

In this post, we will consider silicone pressure-sensitive adhesives and their role in current tape applications.

What are they?

Silicone adhesives contain two major components- a flexible silicone gum and a crystalline siloxane resin. By varying the concentrations of these two ingredients, the adhesive properties can be adjusted to meet the demands of various applications.

What’s unique about them?

Silicone pressure-sensitive adhesives are highly specialized and are selected in applications that demand resistance to extremely high or low temperature, moisture, and chemicals.

They are considerably more expensive than either rubber-based or acrylic adhesives and tend to be used in niche applications.

As you can see in the above table, their low glass transition temperature (Tg) allows them to perform in extreme cold without debonding or at an extremely elevated temperature without drying out. Silicone adhesives don’t typically exhibit aggressive tack or high peel values BUT they adhere extremely well to low surface energy materials such as silicone rubber, release liners and fluoropolymers that acrylics and rubber based adhesives cannot. They also exhibit high dielectric strength and are used extensively in electronic and electrical applications.

Common Applications

Silicone adhesive applications include splicing tapes for silicone release liners, fabrics, and elastomers, electrical tapes for insulation resistance, plating, masking, and soldering tapes for electronic applications, and masking tapes for plasma an flame spray processing where high-temperature resistance and clean removability are required.

Silicone adhesives are truly for niche applications but they punch above their weight and can handle conditions that rubber-based and acrylics just can’t. Want to know more about silicone tape products? Call Tom Brown, Inc. to learn more!

Gasketing and Sealing Materials for Indoor and Outdoor Lighting Applications

Indoor and outdoor lighting systems require different types of gasket materials to provide reliable seals against various environmental conditions. These die-cut parts can be used as housing gaskets, lens seals and to assist with thermal management.

Housing Gaskets

Indoor housings or enclosures are often made from painted metals and need to be sealed against moisture, dust, and air. PVC foams can provide an ideal seal and an economical solution. They are easy to apply, can be delivered in die-cut form, strips, or rolls, and provide a tight seal if they are compressed at least 30%. PVC gaskets meet the FMVSS 302 flammability standard, however, PVC is not recommended if the operating temperature of the housing will exceed 150°F.

Outdoor Lighting Seals

Outdoor lighting will typically see more temperature extremes and the gaskets will need to be much more robust to seal against windborne dust, dirt, snow, etc…  Silicone materials are a much better choice for these types of applications.

Silicone gasket materials include silicone foam, solid rubber, and reinforced sponge rubber. These materials offer good compression set resistance and can tolerate temperature extremes from -100° to +500°F. The reinforced sponge rubber incorporates a fiberglass mesh and eliminates any outward extrusion under pressure.

The silicone sponge rubber is a UL recognized weather seal gasket material and fire retardants can be included to meet UL 94V-0 flammability rating.

Solid silicone rubber can be provided in various durometers from soft 30Shore A to firm 70 Shore A. These materials also can be formulated to be low outgassing. Outgassing becomes critical in Led lighting where excessive outgassing can degrade the output and performance of the LED light source.

Adhesive Options

PVC foams typically feature an acrylic adhesive system. These adhesives typically bond very well to painted and unpainted metals and tend to serve as a fixturing adhesive until the gasket is placed under compression.

Higher performance acrylics can be applied to some of the silicone materials and offer temperature performance from -40°-+350°F. These adhesives can handle many outdoor applications for all but the most demanding applications.

Silicone pressure –sensitive adhesives can also be applied to most of the highest performance gasket material and can match the -100° -+500°F range of the gasket itself.

Tom Brown, Inc. supplies die cut and roll form gasket and sealing materials that meet tight tolerances, meet industry standards for flammability and outgassing properties and perform as intended in almost any environment. Contact us today for design assistance and help with your gasket and adhesive selection.

Understanding Rubber-Based Pressure Sensitive Adhesives in Tape Products

History

In 1845, a surgeon named Dr. Horace Day made the first crude surgical tape by combining India rubber, pine gum, turpentine, litharge (a yellow lead oxide), and turpentine extract of cayenne pepper and applying that mixture to strips of fabric. It was the first “rubber-based” adhesive and Dr. Day used it in his practice as a surgical plaster.

Larger scale manufacturing of similar medical tapes began in 1874 by Robert Wood Johnson and George Seaburg in East Orange, NJ. That company would soon become the Johnson & Johnson Company we know today. Later in 1921, Earle Dickson who bought cotton for Johnson & Johnson noticed that the surgical tape kept falling off his wife Josephine’s fingers after cutting them in the kitchen. He fixed a piece of gauze to some cloth backed tape and the first Band-Aid ® was invented.

It took almost 75 years from Dr. Day’s first crude tape until the early 1920’s when the first industrial tape application appeared. The application was electrical tape (although the adhesive was more of a cohesive film than the electrical tape we know today) to prevent wires from shorting.

The second major industrial tape application was a result of the rise of the American automobile in the 1920’s. Two-toned automobiles were becoming popular and automakers needed a way to produce clean, sharp paint lines while using the new automatic paint spray gun. They started using the surgical tape that was available but the paint wicked through the cloth backing and caused defective paint jobs.

Richard Drew, an engineer at Minnesota Mining and Manufacturing (3M) happened to be at a local body shop testing their WetorDry® brand sandpaper in 1925 and he saw the workers struggling to get clean paint lines. He went back to his lab and created a 2-inch wide crimp backed paper tape that became the first “masking tape” for painting.

Jumping ahead to 1942 and World War II, Johnson & Johnson developed duct tape to seal canisters and repair equipment for the military. The tape was a basically a polyethylene coated cloth tape with good “quick stick” properties that made it easy to use in the field for emergency repairs. The world never looked back and duct tape can be found in almost any home or toolbox.

What are Rubber Based Adhesives?

In simple terms, a rubber based pressure-sensitive consists of a natural or synthetic rubber to which various tackifying resins are added along with plasticizers, antioxidants, pigments, and UV stabilizers. These formulations can be delivered to the coating machine dissolved in organic solvents, dispersed in water, or in molten form as a hot melt. Some synthetic elastomers are also curable by radiation such as UV or electron beam(EB).

Natural Rubber Based Adhesives

The naturally occurring rubber harvested from rubber trees is the oldest type of adhesive base and is still in use today in various masking tapes and applications tapes used in the graphics industry. They are inexpensive, can be formulated with predictable adhesion properties, and work well in applications with low shear requirements.  These adhesives work well in ambient and low-temperature applications but will struggle when the temperature exceeds about 120°F.

Synthetic Elastomers

Adhesives and the resultant tapes made from this class of elastomers is very versatile and the most frequently used.

These adhesives typically use styrene butadiene rubber (SBR) or styrene block copolymers such as styrene-butadiene styrene (SBS) , styrene –isoprene-styrene(SIS), or SEBS(styrene-ethyelene/butylene-styrene.. Block copolymers have thermoplastic styrene end blocks with an elastomeric midblock.  Different tackifying resins can be used for each distinct phase of the base and the resulting adhesives can be tailored to exhibit aggressive tack, high peel, and excellent cohesive strength.

There are a variety of tape products made from these systems including double coated film tapes, transfer adhesives, foam tapes, and carton sealing tapes. These tapes can be used for interior bonding and assembly applications, fabricating foam gaskets and seals, and of course duct tape.

Strengths and Weaknesses

In general, rubber based adhesives are not UV or oxidation resistant which is why they tend to be used predominantly in interior applications. Having said that, antioxidants and UV stabilizer packages can be added to the formulation to help mitigate these weaknesses. Some synthetic elastomers exhibit vastly improved UV stability over natural rubbers. Chemical resistance can also be problematic as is resistance to elevated service temperatures (typically 180- 200°F at the top end).

The great strength of rubber-based adhesives is their wide formulation latitude.  These adhesives can be compounded to be removable, repositionable, or extremely permanent. High strength foam bonding tapes can be made from rubber based adhesives or easily removable masking products can also be offered.

Rubber based adhesive adhere to many surfaces including low surface energy plastics such as polypropylene and polyethylene. And to top it all off, rubber based adhesives are economical. They get the job done at a very fair price!

Adhesive tapes made from rubber based adhesives have come a long way since Dr. Day’s first surgical tape and they still offer a cost-effective way to bond, seal, and protect. Contact Tom Brown, Inc. today for samples or more information.