PRODUCT UPDATE
Adhesives and Pressure-Sensitive Components:
Suppliers Focus Efforts on
Advanced Applications
Norbert Sparrow
In many applications, the adhesive function of joining materials is only part of what's expected.
As medical devices become smaller and more complex, greater demands are being made on the materials and components used in them. Adhesives and pressure-sensitive components are no exception.
"Adhesives are being asked to do things that were not the case in the past," says Jeff Noren, marketing manager at Tapemark, Medical/Industrial Fabricating Div. (West St. Paul, MN, USA). "In high-performance components, for example, they need to be able to withstand elevated temperatures and various forms of interference."
The job of an adhesive today, adds Gary Lord, marketing manager for Dow Corning Healthcare Industries Europe (Sophia Antipolis, France), may involve more than simply attaching something to something else. "There may be a combination of needs that have to be taken into account. For example, a manufacturer might be looking for a nonsensitizing material that will work under varying conditions and that will not leach extractables and plasticizers," says Lord.
Considering the multiple types of adhesives in the marketplace, not to mention the capabilities of converters to laminate adhesives with different properties, manufacturers may have a difficult time keeping pace with what's available. Not to worry, says John McGann, project manager for engineered adhesive films at Scapa Tapes (Bellegarde, France). "Use your supplier as a consultant," he suggests.
"Instead of asking what kinds of tapes are available, companies should turn it around and ask the vendor what it can do for them. A lot of people try to make a product by using what's available," McGann adds, "when they could derive a great deal of benefit simply by changing the coating weight or using a different substrate."
To make the most of your supplier's expertise, you should get him involved as early as possible in the product design phase, says Noren. "There are so many options available, that the earlier we can come to the table with proposals, the more useful we can be. We can make suggestions of ways to modify the design—adjusting a radius or simply approaching a process in a different way—that can reduce production costs." Don't limit your options by shopping for an adhesive after you've designed the part and settled on the assembly process, Noren stresses.
According to Arne Kaaber, marketing manager at 3M a/s, Medical Specialties (Glostrup, Denmark), and Lord, manufacturers should take into account the breadth of expertise that a supplier can draw upon. "We have a vast technology base in-house," says Kaaber, "not just in relation to health care, but in a lot of areas." That is the supplier's edge, he adds, when the project calls for a custom solution. Likewise, Lord points to the pressure-sensitive technology developed by Dow Corning that spans more than 30 years and has been adapted to everything from standard industrial to high-tech applications.
Suppliers also stress the importance of verifying that appropriate quality assurance protocols are in place. This is a critical issue, according to Karen Kline, vice president of sales and marketing at Acutek (Muttenz, Switzerland). "We devote practically 100% of our marketing effort to the medical device industry," says Kline, "and back in the early eighties we voluntarily registered with US FDA as a medical device manufacturer." The rationale for doing so, she adds, was a belief within the company that to truly serve the industry, Acutek should be regulated by the same guidelines as its clients. "We're on the same wavelength," she says, and that allows the company to anticipate needs specific to the device industry, such as traceability of raw materials and process control.
Testing is equally important, adds McGann, and manufacturers should ask pointed questions about the type of testing that has been performed regarding biocompatibility, for example. Nor should the manner in which a product is evaluated be neglected, adds Kaaber. "Everyone is looking for an adhesive that will adhere to moist skin," he explains. "But there is a difference between putting an adhesive on dry skin and then exposing it to moisture, and placing an adhesive on wet skin." He also cites an example of a clinical test of a pressure-sensitive that was placed on people's backs. "When it was removed, the product did not appear to be too aggressive. But when it was used in an area where the skin was more sensitive, with an ostomy bag for example, it hurt!"
Manufacturers face these and numerous other issues when shopping for adhesive materials and components. Suppliers with a focused knowledge of their product category and with experience serving the medical device industry, such as those profiled in this section, can be a valuable source of help. In some cases, they may even be able to suggest less costly and more efficient alternatives that you had not considered. "Tell us about the end product you're trying to make," says McGann, "and we may be able to say, 'Hey, wait a minute, there's a better way to do that.'"
Products:
Tapemark, Medical/Industrial Fabricating Div.
A contract fabricator of custom adhesive components and assemblies for the medical device, electronics, and computer disk drive industries, Tapemark, Medical/Industrial Fabricating Div. (West St. Paul, MN, USA) recently opened offices in Ireland and Northern Ireland and entered into an agreement to be represented in Singapore. "We work with a lot of multinational companies," says marketing manager Jeff Noren, "so it's helpful to be nearby to facilitate discussions."
Along with the company's manufacturing capabilities that include rotary and reciprocating die-cutting, laminating, slitting, level winding, and packaging in a cleanroom environment, the firm has expertise sourcing pressure-sensitive adhesives, films, foils, double- and single-coated foams, conductive adhesives, hydrogels, and hydrocolloids. "We may take an adhesive designed for a straightforward application that is presented to us in a raw form and laminate it to another adhesive," explains Noren. "We may introduce a hydrocolloid or hydrogel and end up with a finished part that's a combination of several different adhesives." The demand, he adds, is for higher-tech applications, and Tapemark is well positioned to meet that need, according to Noren.
The company recently invested in rotary laser die-cutting equipment. "This machine has the capability of making much smaller holes than traditional rotary or reciprocating die-cutting equipment," says Noren. The holes are very clean, he adds, and as the material is moving through the press, the laser travels along with it and cuts the pattern. "The electronics industry is very excited about it, and I have to believe that we'll start seeing applications for medical device manufacturers very soon."
The company, which is certified to ISO 9001 and EN 46001, also offers complete technical development assistance, supporting customers from the design and regulatory approval phases to full production.
Acutek
A converter of pressure-sensitive materials that offers contract manufacturing services, Acutek (Muttenz, Switzerland) works closely with adhesive coaters to incorporate the latest technological advances in adhesive chemistry and tape construction. The company has experience working with a broad range of materials, and it manufactures components used in everything from wound-care products to pulse oximetry equipment. But what truly sets the firm apart from the competition, according to vice president of sales and marketing Karen Kline, is its in-depth knowledge of the medical device industry.
"We voluntarily registered with US FDA as a medical device manufacturer back in the 1980s," says Kline from the company headquarters in Inglewood, CA, USA. "In order to truly serve the industry, we believed that we should become a part of that industry and be regulated by the same guidelines. When someone comes to us for contract manufacturing, it's not necessary to go into a lot of laborious detail about what we have to do in terms of tracing the raw materials, process control, and so forth," adds Kline. "We are already on that wavelength."
In-house capabilities include flexographic printing, precision rotary or flat-bed die-cutting, and multilayer lamination. Specialty packaging services, including tamperproof seals, antifog package windows, and custom patterned-adhesive lidding, can also be provided. The company, which is certified to ISO 9002, is currently pursuing ISO 9001 and EN 46001 certification. According to Kline, that process should be completed before the summer.
Matrix Precision Converting
In addition to providing a complete array of contract manufacturing services, Matrix Precision Converting (Winsford, Cheshire, UK) supplies a range of adhesive products. The products, which include some that are suited for pediatric and geriatric devices, can be applied to standard or custom shapes according to customer requirements. The company has gained valuable experience over the years sourcing materials and designing, packaging, and producing a variety of adhesive medical devices, says manager Ron Brenwall. "This allows us to offer customers everything from precision manufacturing according to their specifications to the complete procurement, production, and packaging of their products, ready for distribution anywhere in the world."
The company has experience working with a diverse range of raw material groups, including high-MVTR films, foils, papers, foams, wovens, nonwovens, hydrogels, hydrocolloids, and custom laminations. Products typically manufactured include conductive adhesive electrodes, hydrocolloid adhesive products, diagnostic kit components, fixation devices, ostomy products, and custom medical devices.
To ensure that products are produced efficiently and in a cost-effective manner, the firm maintains statistical process control documentation; in addition, all processes and systems adhere to good manufacturing practices and ISO 9001 standards. Manufacturing and packaging operations are conducted in Class 10,000 or Class 100,000 cleanrooms.
3M a/s, Medical Specialties
"We are a health-care company ourselves," says general sales and marketing manager Arne Kaaber, "so we know the market as well as the needs of device manufacturers. And we have a vast technology base in-house--not just related to health care but to many other fields--and we can draw on this expertise for the customization of existing products, for example."
The capabilities of 3M a/s, Medical Specialties, (Glostrup, Denmark) encompass hypoallergenic adhesives and backings, coating technology, converting and laminating, as well as woven and nonwoven materials. Tapes and adhesive components are manufactured according to good manufacturing practices, and the company's production facilities are certified to ISO 9002. "We also do extensive testing and clinical evaluations of our products," notes Kaaber. "For the customer, this can result in a substantial reduction in paperwork and lead to significant cost savings."
A variety of pressure-sensitive medical-grade tapes are supplied by the company. Single-coated tapes are available as microporous or occlusive woven, nonwoven, or elastic constructions. Double-coated tapes and transfer adhesives used in joining two surfaces withstand sterilization and can be die-cut. Plastic tapes and films that provide fluid and barrier properties, release liners, heat-sealable films, refastenable tape closure systems, and wire tape are also part of the company's product range. A recent addition, according to Kaaber, is a hydrocolloid that represents an improvement over what was previously available. "The hydrocolloid that we recently introduced is devoid of cold flow and is less aggressive to the skin than comparable products."
Collano Ebnöther AG
A company that specializes in the development of custom products for individual applications in medical tapes and bandages, elastic bandages, surgical drapes, and electrodes recently introduced hot-melt pressure-sensitive adhesives (HMPSA) for medical uses. The new Collano Ecomelt HMPSA represents an ecological and physiological alternative to the solvent-based adhesives that are still widely used, according to Beat Stäuble, marketing manager for Collano Ebnöther AG (Sempac Station, Switzerland). "As an HMPSA pioneer in the medical sector that has worked with leading medical device manufacturers worldwide," says Stäuble, "we believe that we are setting new standards with the introduction of this product line based on UV-curable adhesives."
The company's technical support services include the performance of coating trials on original materials and optimization of application parameters.
Avery Specialty Tape Division N.V.
Avery Specialty Tape Division N.V. (Turnhout, Belgium) has introduced an inherently breathable adhesive for medical applications. According to business director for medical Colleen Ward, the product has been chemically structured to enable moisture vapour to pass through the closed adhesive layer.
"Breathability is normally achieved by means of dot coating or by mechanically creating spaces in the adhesive to produce a discontinuous layer," says Ward. "But these methods increase the potential for bacterial penetration." This possibility is significantly reduced with the company's new T2400 adhesive.
While the actual MVTR level of the final construction depends on the carrier substrate, Ward cites the example of a breathable polyurethane film coated with the adhesive that routinely achieved MVTR values of approximately 3000 g/m2 over 24 hours. "Expressed another way," adds Ward, "approximately 75% of the film's MVTR level was retained."
Depending on the application requirements, the adhesive can be tailored to exhibit different physical properties. It has been tested to ISO 10993-1 by NAMSA.
Avery Specialty Tape Division N.V. supplies a wide range of adhesives, films, foams, nonwovens, and other components to medical device manufacturers seeking to customize existing products. The company's standard range is designed for a variety of applications from surgical drapes and incision films to electrode terminal mountings and diagnostic products. Pressure-sensitive systems include single- and double-coated constructions as well as adhesives formulated to specifications in the company's in-house laboratories. The firm is certified to ISO 9001.
Scapa Tapes
"We're not necessarily looking for the giant application," says John McGann, project manager for the engineered adhesive films division at Scapa Tapes (Bellegarde, France). "Manufacturers often use a material that may be the best available on the market, but what they are really looking for is something special, something different. We can offer that added value in the specialty application," continues McGann, "and give our customers exactly what they want." One recent project involving a tape design for disposable stimulation electrodes illustrates this point.
Prior to a redesign of the electrodes, the assembly process relied on a hot-melt adhesive and single-sided vinyl adhesive tapes. Design engineers at Cardiotronics Systems Inc. (Carlsbad, CA, USA), which manufactures the electrodes for use with defibrillation, ECG, and external pacing equipment, specified a double-coated foam adhesive tape to replace the old design. Scapa Tapes developed a cross-linked double-coated polyethylene foam tape containing a hypoallergenic acrylic adhesive on both sides.
An inchwide ring of foam tape makes up the outer border of the electrode pad. One side of the tape is joined to a similar ring of single-coated foam tape, which is bonded to electrically conductive tin. The other side is attached to a release liner.
Replacing the hot-melt adhesives with foam tape "simplified the bonding process and virtually guaranteed that a consistent amount of adhesive is applied each time a pad is manufactured," according to Cardiotronics general manager Tim Way.
This is one type of project that Scapa excels at, adds McGann. "Without betraying the trust of anyone we have worked with, we may be able to say to a supplier, 'Hey, there's a better way to do that.'"
NuSil Technology
Pressure-sensitive adhesives suited for use with hair pieces, special-effect appliances, electrodes, prosthetics, male incontinence devices, and related products can be applied either to the device or to the skin. "The solvent evaporates once the dispersion has been applied," explains Brian Nash, vice president of sales and marketing at NuSil Technology (Carpinteria, CA, USA and Anglet, France), "leaving behind a tacky silicone layer that can be adhered to another object through application of pressure."
The company supplies three types of pressure-sensitive adhesives, which are distinguished by the carrier they contain. PSA-9839 has an ethyl acetate carrier, which is an industry standard, while PSA-9931 uses a 1,1,1 trichloroethane carrier. PSA-9930 is a unique product, according to Nash, because its hexamethyldisiloxane carrier is relatively odourless. "That makes it particularly user-friendly," says Nash. In addition, the solvent has been classified as a nonvolatile organic compound by the US Environmental Protection Agency, making it environmentally friendly as well.
NuSil Technology is certified to ISO 9001. The company develops, manufactures, and supplies silicone materials to a broad range of industries and offers silicone testing services in its laboratories.
Dow Corning Healthcare Industries Europe
"The majority of adhesives on the market are organic based, and they consequently house a number of components such as plasticizers, tackifiers, and emulsifiers," says Gary Lord, marketing manager for Dow Corning Healthcare Industries Europe (Sophia Antipolis, France). "These can react with the skin in some cases. The reaction can be mild or it can be quite severe, resulting in skin sensitization. Silicone pressure-sensitive adhesives contain no additives—they are 100% silicone and the adhesion comes from the technology that is built into the adhesive," explains Lord.
Other advantages of silicone pressure-sensitives include retention of adhesive properties in the presence of moisture or perspiration and permeability to moisture and gases. The adhesives, which meet or exceed current USP Class VI plastic tests, are nongumming and nonpeeling as well. "They are especially well suited for applications where something needs to be attached to the body for a reasonable amount of time in circumstances where there is potential for a lot of moisture," says Lord. "In these situations, a standard type of organic adhesive would either curl up or fall off."
Medical applications include ileostomy and colostomy devices, patient-monitoring devices, surgical dressings and pads, maxillofacial prosthetic devices, and use as a nonsensitizing barrier material between adhesive tape and the skin.
Certified to BS EN ISO 9002 and operating in accordance with good manufacturing practices, the firm has extensive experience in pressure-sensitive applications. "The technology developed by Dow for the industrial applications of pressure-sensitives goes back more than 30 years," says Lord. "This expertise is not limited to health care. Dow is active in a huge number of fields, and we can draw on those resources."
Emerson & Cuming
A formulator of adhesives, encapsulants, coatings, and sealants, Emerson & Cuming (Westerlo, Belgium) has developed a UV and visible-light cure adhesive that bonds flexible polyvinyl chloride and polycarbonate substrates in a matter of seconds. Eccobond UV 9115's low viscosity, according to the company, makes it suitable for use in applications that require flow around tight-fitting components. The USP Class VI adhesive is durable and flexible, and can withstand gamma sterilization. Tubing connections and catheter and oxygen-mask assemblies are among the suggested medical applications of the material.
