Trends in Gloves and Glove Liners
Critical environments demand ultra-clean gloves, whether manufactured of latex, vinyl, nitrile or other blends. They must be durable, but flexible and lightweight, providing dexterity and protection as well as comfort.
By Susan English
The trend to newer, cleaner materials, longer lengths and more variety in ambidextrous styles make this an exciting time for cleanroom-compatible glove manufacturers and distributors. It means better quality control during processing and packaging. Generally manu-
factured in latex, vinyl or nitrile, cleanroom gloves can be judged on a number of criteria, such as chemical resistance, physical/mechanical strength, comfort, dexterity and length. A glove`s thickness is expressed in mils (5 mils = 0.005-in. thickness). Thinner gauge means greater operator dexterity. Glove size is measured as the circumference of the palm at its widest point in inches. Length is an important factor in protecting exposed skin from chemicals or shielding the product or process from skin flakes, bacteria and skin oils.
Latex or natural rubber gloves are widely used and are still considered by many the industry`s “gold standard” for durability. They exhibit excellent strength and barrier capabilities, the ability to conform to the hand for greater tactile sensitivity and dexterity–and they have superior stretchability, which minimizes glove breakthrough. It is also a well-known industry statistic that approximately five percent of the American work force is allergic to latex and the powders used with them.
The new synthetic materials–PVC (polyvinylchloride), nitrile and polymer blends–are becoming more and more popular, according to glove distributor Craig Lissner, president of OrthoCare, Inc. (Chicago, IL), who predicts synthetics possibly replacing latex as the big seller of the future. “Latex will always have its niche, but our manufacturers are getting more and more inquiries about synthetic gloves because of the various attributes they offer–especially for those workers who are allergic to latex and vinyl,” he says.
Although vinyl gloves do not eliminate the risk of a Type IV irritation or allergic reaction caused by chemicals present in both vinyl and latex gloves, individuals who have a Type 1 allergic reaction to latex proteins may wear vinyl in a powder-free environment. Usually available in powdered, non-powdered, cleanroom and antistatic versions, gloves made of vinyl are light gauge and inexpensive and provide a high level of dexterity, although they are not nearly as durable as latex nor as good a barrier. For more critical operations where barrier protection is needed, users may need to wear more than one pair.
More durable than vinyl and growing in popularity is nitrile, or synthetic rubber, which has always been recognized as a highly durable glove compound. It is also form fitting and has greater sensitivity than vinyl, which can have a baggy fit. A somewhat inelastic polymer, nitrile can be difficult to form into the thin, disposable glove demanded by industry. However, manufacturers are continually making improvements–so much so that current demand exceeds supply.
Latex gloves
Chemical- and acid-resistant latex gloves are offered by Liberty Industries, Inc. (E. Berlin, CT). The Model 7349 washed and powdered latex glove is 12-in. long and 6 mil thick. The gloves come paired and color-coded by size and are lot traceable. Calapro Inc. (Yorba Linda, CA) offers powder-free latex gloves with low particles and extractables in a super-thin 7-mil gauge for Class 100 applications. The company uses a chlorination washing method to maximize protection against contamination and features lot traceability. Static-dissipative, natural rubber latex cleanroom gloves are offered by Hauser Products, a division of North Safety Products (Charleston, SC). The gloves are designed to reduce losses from voltage over-stress, and because they are inherently static dissipative, do not depend on humidity or ingredient migration, won`t weaken with age, degenerate with rubbing or washing, or allow static buildup on the hand, according to the company. Packaged in conductive bags so they can be taken into the work area, the gloves meet ASTM D 3578 requirements. Hauser also manufactures Series 100 finger cots, which are cleaned in a cleanroom. Its Series 200 cots are mechanically cleaned, and the Series 300 are available in a powdered version.
QRP, Inc.`s (Tucson, AZ) ambidextrous latex gloves, designed for Class 100 use, are formulated without silicone oil or plasticizers. They are designed to provide a high level of comfort and tactile sensitivity for IC manufacturing as well as general manufacturing or assembly. The company`s processing method guarantees consistently low extractable, particulate and reactive ion counts, according to IES RP-005, and the gloves are lot traceable.
PVC (vinyl)
Southern Pacific Coast Corp. (Diamond Bar, CA) features Durasafe powder-free vinyl gloves and powder-free disposable latex gloves, which have been developed to solve the problems of particulate contamination in electronic parts assembly, medical component manufacturing, food processing, medical examination and other industries where cleanroom conditions must be maintained. The seamless gloves are treated with a series of chlorination processes to ensure low-particle counts and easy wear and removal. Hal Sharpe Associates, Inc. (Chico, CA) carries lint-free, vinyl-coated gloves suitable for material handling operations. The gloves feature a vinyl barrier palm and a breathable nylon back, as well as an extra-long cuff for wrist protection. Color-coded hems allow easy size identification. The gloves are packaged in a Class 10 cleanroom.
Nitrile
For nitrile users, Safeskin Corp. (San Diego, CA) has introduced its HypoClean Powder-Free Nitrile Glove for use in Class 1,000 or better controlled environments. Containing no natural rubber proteins, the HypoClean glove is hypoallergenic and virtually odor free. The glove also offers ESD characteristics superior to those of latex gloves, according to the company. The 6-mil ambidextrous glove is available in sizes S, M, L and XL and is packaged in sealed poly bags to minimize contamination.
Ansell Edmont Industrial (Atlanta, GA) introduces a new, thin-mil nitrile glove called “Touch N Tuff.” Only 4 mils thick, the glove provides three times the puncture resistance of competitive natural and vinyl gloves, according to the company, as a result of a newly developed technology called Thin Nitrile Technology, or TNT. New from UA Products (San Francisco, CA) is a 12-in. nitrile glove with ESD characteristics the company expects will find widespread use in the disk drive industry for manufacturing drives using magneto-resistive (MR) heads. An ambidextrous glove with low extractables, the UA 10n, UA 100 and UA 10 are laundered in a Class 10 laundry to reduce particle count. InterWorld (Fremont, CA) introduces its triple-washed nitrile glove especially for disk drive manufacturers in MR head programs. Its Nitristat glove features static-dissipative properties ran ging from 107 to 109 Ohms/sq. It also has a high tolerance for a broad range of chemicals and, according to the company, contains no plasticizers, phthalate esters, silicone or magnesium silicate.
Advanced Clean Room Devices (Santa Fe Springs, CA) has a new nitrile glove. It is designed for cleanroom use especially where electrostatic discharge is a concern. Particle count data per IES-RP-CC-005-87-T, extractable analysis results and nvr residue test data are available.
Blends, reusables and gloveboxes
New from Mapa Professional (Willard, OH) is the TRIonic EO-204 glove for acid protection in clean environments requiring orange acid glove identification. Pigment-free, the gloves feature an orange band on the inside of the cuff edge. The EO-204 gloves are a blend of natural rubber, nitrile and neoprene, offering the comfort of natural rubber with the enhanced chemical protection of nitrile and neoprene. A raised diamond grip offers wet handling capability, and a reduced taper or cuff flair helps the glove better adhere to the garment`s sleeve. Each production lot is tested using IES-RP-005 test methods for particles, and the company regularly performs a standard battery of extractable tests. Test results and chemical resistance data are available on request.
New to the synthetic glove market is OrthoCare, Inc.`s 12C 12-in. cleanroom glove made from a proprietary PVC blend of polymers and elasticizers. Manufactured to ISO 9002 standards for GMP-documented quality assurance, the gloves are powder free and cleanroom packaged.
For use in gloveboxes, Renco Glovehaus (Manchester, MA) is developing a new tripolymer glove made of a nitrile acrylic and butadiene mixture, designed to resist VHP (vaporized hydrogen peroxide). VHP is used in the pharmaceutical industry for sterilizing barrier isolation chambers. The ambidextrous glove is designed for an 8-in. port and is about 30 mil and 32 in. long. In addition to meeting the demand for ambidextrous and thin-wall nitrile gloves, the company specializes in niche-oriented, custom orders, supplying replaceable glove hands–right/left or ambidextrous–for use in 12-in., as well as 8-in. ports.
Terra Universal (Anaheim, CA) distributes a comprehensive line of gloves and finger cots to meet cleanroom requirements to Class 10. Gloves are available in a broad range of materials, including natural latex, nitrile, Darlexx, neoprene, butyl, EPDM and nylon. Application specific, they meet requirements for static safety, high and low temperatures and chemical resistance. The company also makes accordion sleeves for glove boxes to go with any size and type of glove. Designed for use with 8-in. glove port flanges, the sleeve section is made of heavy-wall natural latex, which holds its shape under the positive pressure typically maintained inside a glove box. Models are available in 12- and 24-in. sleeve lengths. Cleanroom packaging and certification are available.
A unique product is the Ultrapoly Glove by Twyman Templeton (Ritzville, WA), a cleanroom glove made of ultrapure polyethylene low in particles (<300/CM2), extractables and ash content. It is designed to help increase yields in silicon-growing, wafer fab and other areas where particles, surface contamination or metallics can cause processing problems. Particle counts are measured by the IES 005-87 method, water extractables by the IC, TOC and ICP-MS test methods. Total residual ash after incineration is less than 10 parts per million, and abrasion and GFAA surface transfer tests are also performed, according to the company. Made from pure polyethylene, the ambidextrous glove is cut-resistant, 2-ply,--2 mils per ply for 4-mil thickness.
Unlike most cleanroom gloves, the Ultrapoly is not form fitting. It is manufactured by taking four pieces of pure polyethylene and laminating it at the edges to form the glove, which can be worn over multiple layers of gloves or over the hand alone. According to Richard Rehn, the company`s manager of west coast operations, the highest particle count ever recorded from the gloves was 294 particles. “It never gets touched, which means it never gets contaminated by anything–that`s the manufacturing process,” says Rehn. Although nitrile has a better abrasion rate, he concedes, the Ultrapoly Glove is still very abrasion resistant, and despite its bulky appearance, has “good dexterity.” The glove is 18 inches long and comes in small, medium and large. Lot numbers are sequential and traceable to the film lot used to make the gloves.
An alternative to disposable gloves is “The Hot Glove” developed by TechStyles, Inc. (Hickory, NC) for safe handling of PC boards from burn-in ovens. A washable, reusable polyester-filament knitted fabric glove, it is covered in a polyurethane laminate that is microporous for “breathability” and comfort. Useful for dry applications, the cleanroom-compatible glove is antistatic and heat resistant for general small parts handling and wafer handling and is available in poly urethane-coated, soft and multi-barrier styles. An ESD non-linting shell fabric protects the product, and a Nomex full palm and finger liner protect the operator. While the initial price is higher than for a disposable glove, the reusability factor–15 to 20 times–according to James Foley, TechStyles vice president of marketing–more than makes up for the initial cost. Using an example of an average of seven changes per day at 7 cents per latex glove, Foley calculates the cost of a week`s worth of disposable gloves at $5 per week. “If the (reusable) glove is anywhere between $36 and $100 a dozen and they`re washed at a charge of about 25 cents a week, the reusable becomes very, very cost effective. And they don`t build mounds of non-biodegradable latex which doesn`t disintegrate,” he says.
Glove liners
Berkshire Corp. (Great Barrington, MA) offers its expanded line of glove liners to provide comfort and protection during prolonged glove use in critical environments. BCR half-finger, full-finger and heavyweight full-finger ambidextrous, glove li ners are made of continuous-filament polyester and constructed to allow moisture to be absorbed and drawn away from the skin, while protecting latex or PVC glove wearers. The liners are launderable, and a special seamless technique keeps gloves from raveling. Wells Lamont Technologies Inc. (Houston, TX) manufactures a reusable nylon glove liner which can be laundered between 30-40 times without losing its integrity. Designed for use as a gowning glove, inspection glove or glove liner, the long-extruded, continuous fiber filament eliminates shedding. The company says the compressed-filament yarn gives high stretch characteristics and a “thin” feel for tactile sensitivity and improved comfort.
The GloveLock2 Glove Sealing System from The Carpenter Group (Pacific Grove, CA) creates a friction-seal between the glove and garment sleeve to prevent the glove from rolling or sliding away from the sleeve of the garment.
Bowman Medical Products (Boise, ID) offers the Glove Butler spring-loaded glove dispenser. The Glove Butler comes with wall-mounting brackets in a variety of materials, including stainless steel, baked enamel, aluminum, plexiglass and colored plastic. Models are available in widths of 5.5 in. and 6.5 in., 10 inches in height and a depth of 3.75-in. A Bulk Dispenser, measuring 7 in. wide ¥ 12 in. high, and Bulk Double Dispenser, measuring 13 ¥ 7 ¥ 4.5 in. are also available.
Glove and Apparel Dispensers from Terra Universal provide clean, organized storage of gloves, finger cots and other cleanroom apparel. Select dispensers made of lightweight acrylic or transparent static-dissipative PVC. n
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Gloves-More than a Commodity
Absolute Quality Leadership, (AQL; Santa Maria, CA), sees quality control as a top priority in glove manufacturing. Says Director of Sales and Marketing, Denise McAvoy: “There`s so much focus on garments, because obviously, they cover a very large surface area of a very dirty object in the cleanroom, but it`s the glove that cleans the equipment, touches the wafer boats, and touches the garments. So what we`re now seeing is that customers are recognizing that gloves are a very critical component of the whole cleanroom system.”
A company whose roster includes former contamination control officers in both the semiconductor and pharmaceutical industries, AQL certifies each product lot of its VeriClean Cleanroom gloves for physical, particle and extractable data. As part of the release process, independent laboratory testing must be completed before glove lots leave the manufacturing plant in Asia. The hand-specific and ambidextrous nitrile gloves are manufactured for demanding applications in submicron environments, as well as Class 100 and Class 1,000 cleanrooms. The glove dissipates a 5 Kv charge applied to a surface in less than one second with a surface resistivity of less than 1 x 10-10 ohm2. Full batch traceability and statistical process controls are employed during the manufacturing process to ensure consistent performance. AQL also publishes a quarterly report, which provides detailed analyses of product performance. Analytical techniques and equipment are employed to fully characterize product and process attributes. Methods used are Icn chromatography (IC), inductively coupled plasma mass spec (ICP-MS), nuclear magnetic resonance Fourier Transform Infrared Spectroscopy (FTIR), laser liquid particle test technology, gravimetric analysis and ESD analysis. Test methods include IES Recommended Practice for Cleanroom Gloves, Sections 6 and 7, and pertinent ASTM, EOS/ESD and EIA specs.
In addition to contamination from glove materials, ammonium and other heavy metals are becoming more of an issue in critical environments as well, says McAvoy. She cites the recent example of a major western semiconductor fab whose whole stepper line was forced to shut down for a day because polyisoprene particles were found in the stepper equipment, contaminating wafers. “What we`re trying to get away from,” says McAvoy, “is [a scenario] where our customers will say, `a glove`s just a commodity. Give me your best price,` and then six months later, they have a catastrophic failure because the glove they`re using has no controls, they don`t do any testing on it, or it`s the wrong material.”
AQL`s services also include product characterization studies performed by independent test laboratories, customized product data packages, ongoing development of new glove test methods, test method and laboratory correlation studies, a ship-to-stock program, custom glove product development, a special latex allergy education and resource library, a product quality (complaint) response program, and competitive glove studies. Also, McAvoy says AQL “takes customers out of the inspection business” by sharing performance data, test methodologies and laboratory correlation studies. A scientific advisory board provides a forum for ongoing customer feedback about industry technology and process advancements, new indirect material supplier requirements and glove test methodology and correlation issues. The company also encourages joint test method development projects with its customers. –SE