User preference shifts to nitrile gloves
SAN FRANCISCO — A major market shift is underway toward synthetic gloves, based on both technology advances and customer demands. According to John Varos, corporate technical director of Best Glove Manufacturing (Menlo, GA), “demand has taken off so much that we`ve doubled the size of our manufacturing locations, as well as purchased a new facility in Johnson City, TN.”
Within the cleanrooms segment of the industry, the largest and fastest-growing segment of the non-medical glove category, according to market researcher Frost & Sullivan, three major glove categories currently exist: natural rubber latex (NRL), nitrile, and poly-vinyl-chloride (PVC), also called vinyl. Their composition, characteristics, price, and challenges vary greatly.
PVC, or vinyl, gloves were the first gloves to make their way into cleanroom use. When manufacturing gloves, 50 percent in volume of oil (diethyl-xexyl-phthalate) is added to give the product pliability and stretch. Again, given the number of chemicals that make up PVC gloves, particle count is a major problem — but the real issue with their use is, because of the oil, they outgas. Several cleanroom segments where molecular contamination is a consideration avoid PVC.
Natural rubber latex (NRL) grew in popularity, addressing several issues that vinyl didn`t — lower in particle count, lower in non-volatile residue, and substantially more comfortable and durable for wearers. Although made of natural rubber, they contain between 15 to 20 ingredients including accelerators, antioxidants, and release agents to help the gloves cure rapidly when heated. The newly manufactured glove has an extremely rough surface with high levels of releasable particles. Instead of the powdering that takes place for the medical segment to ensure a smooth surface, gloves are placed into a chlorinated wash, forming a neoprene anti-stick surface. Two major downsides exist: they have substantial extractable materials (ions of sodium, potassium, chloride, calcium, etc.), and natural rubber proteins may cause allergy.
Today, the shift is toward nitrile gloves. Compared to latex, nitrile has several advantages: durability, chemical resistance, and superior ion-extractable contaminant levels. According to Harold A. Smith, chair of the IEST working group covering cleanroom gloves and finger cots, “A recent study performed by IEST indicates that if you assign the outgassing of vinyl a 10, latex would have a range of 3 to 4, and nitrile less than 1. It`s measurable, but minimal.”
Research and development in nitrile gloves has been a major focus for many manufacturers due to public concern with natural latex allergies. “This March, we`re introducing a nitrile glove called CleaN-dex, with a patented formulation that, once the glove is stretched over the hand, allows the glove to conform to the hand as the glove relaxes, exerting little or no pressure on the skin,” says Varos. “Another major consideration of this type of glove is its anti-static properties. It has a surface resistivity of 1010 ohms/square compared to an industry average of 1015 or 1016 — making it ideal for hard disk drive cleanrooms.”
“What cleanroom customers want to know,” says Mike Gilchrist, senior market manager of Safeskin Corp. (San Diego), “are levels of contaminants present on gloves: particles, ion and elemental extractables, and [non-volatile residues]. We provide certificates of analysis on our products, as well as product line performance history summaries so that customers can see the consistency of our performance levels. The industry is expanding — it`s very competitive. The combination of competition and technology has driven products toward higher levels of cleanliness for customers.”
Frost & Sullivan`s recent report, “The North American Non-Medical Glove Market Ripens Due to Mounting Demands,” breaks the industry into two categories — NRL and synthetic gloves. In 1995, the ratio of NRL to synthetic gloves was 65:35; by 1998 it had changed to 62.5:37.5; and in 2004 the ratio is forecast to be 55:45.
Laurence Ravat, industry business manager for Frost & Sullivan`s medical device group, explains the market trend. “Cleanrooms are rapidly moving to nitrile gloves, and revenues are reflecting that move (see figure, page 1). The NRL glove market is still growing but the growth is slowing. To effectively compete with nitrile,” she says, “NRL cleanroom gloves will drop in price over the next several years.”
According to Ravat, nitrile gloves resist many acids and bases, offering resistance to temperature extremes.
She adds that, “nitrile represents the fastest-growing segment in disposables — accounting for 31 percent of revenues in 1997 and an expected 40 percent in 2004. And, on top of the move to nitrile, cleanrooms is the fastest growing end-user segment.”
Several within the industry believe that potential allergic reaction to natural rubber proteins is a consideration in the switch to nitrile. Gilchrist agrees with that claim, but adds, “by cleaning gloves so thoroughly for critical environment applications, the levels of proteins are substantially reduced, reducing the incidence of allergic reaction and dermatitis.”