Defoamer creates havoc in glove factory!

Manufacturer:We manufacture a range of different types of gloves using natural rubber and synthetic latices. In recent months, we have been encountering some surface defects that are causing havoc in our factory after using defoamer. Your advice please.

JohnWoon:Since defoamers work by virtue of their incompatibility with latex, this incompatibility could lead to defects such as fisheyes, craters, pinholes, oil spots, thin spots etc. This designed incompatibility is responsible for the inability of the latex to completely wet the incompatible component in the defoamer.

I have two strategies to propose: 1) keeping the existing defoamer and controlling its incompatibility 2) Select a new defoamer.

If you're happy with the performance of the defoamer as regards the reduction of webbing and air bubbles, try reducing the level. You could also increase the soap/surfactant(s) employed in the latex compound so as to achieve the same result. The surfactant approach works by reducing the interfacial tension between the defoamer droplet and the water leading to smaller droplets being formed. This approach may also cause a reduction in the interfacial tension between the droplet and the latex. The end result is better compatibility. However, while you're doing this, keep a watch over the webbing and foaming tendency of the latex. You don't want to revert to the situation that prompt you to add defoamer in the first place!

Alternatively, work closely with your defoamer suppliers to select another defoamer that has been formulated properly with the correct emulsifier/surfactant system so that the defoamer droplets formed when introduced into your latex compound are too small to create havoc but large enough to still control the webbing and air bubbles.

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Problems with milling of rubber chemical dispersions for medical gloves

Manufacturer:We are a medical glove manufacturer and have been plagued with countless nightmarish problems with some problems with our bead mills. The final grind and particle size of our rubber chemicals (accelerators, ZnO, sulphur and antioxidants) have been very erratic since we began making our own dispersions. We would appreciate if you could give us some guidance for us to conduct our investigation.

JohnWoon:The variables you need to look into are dwell time, beads to mill-base ratio, temperature, and dispersion formulation.

Generally, accept may be for ZnO, the longer the milling time (dwell time), the finer the grind. Charging of the mill-base at a slower speed and/or reducing the pumping rate would have similar effect. The quantity of your beads in relation to that of the base should be accessed and predetermined for each chemical, for instance, a higher or lower quantity of the beads could lead to good or bad results. If you have only a small charge, a large quantity of beads would only result in an increase in your energy cost unnecessarily to drive the dead weight!

Check the temperature. For some dispersions like those encountered in the paint industry, the advice is to run at maximum temperature allowable before the chemistry of the ingredients start to change while others require lowest temperatures possible.

Last but not least, be careful in the formulation design for the dispersions in terms of particles re-agglomeration, phase separation and viscosity. A wrong formulation would not work even with a wide spectra of dwell times and bead:mill ratios.

I suspect that your problem is due to misguided formulations since the milling part could be quite straight forward if you follow the instruction of the mill manufacturer. To cut short your study and investigation time and therefore your cost, guide formulations for all the chemicals you need for your gloves can be made available to you if you e-mail me your request. Needless to say, you'd get lesser nightmares a lot quicker this way!

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Dow Reichhold Specialty Latex has Announced a Worldwide Price Increase for Nitrile Latex

There is still no sign of easing of the oil price in the medium to long term. Owing to the continuing escalation in raw material and energy costs, Dow Reichhold Specialty Latex has announced on July 24, 2006 a worldwide 5% price increase for nitrile latex used in the manufacture of gloves. The new price would be effective July 15, 2006.

The main raw materials namely methacrylic acid, acrylonitrile and to a lesser extent butadiene, have been negatively affected by feedstock availability as well as supply constrain due to increased demand.

(Dow Reichhold Specialty Latex and its parent company Reichhold, Inc., have been part of the glove industry since the 1960's. Dow Reichhold Specialty Latex LLC is a 50/50 joint venture of The Dow Chemical Company and Reichhold, Inc. The company is headquartered in Research Triangle Park, North Carolina, U.S.A)

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There is no stopping of world demand for medical gloves!

There is no stopping of the demand of medical gloves from the USA and Europe. The demand is now expanding in Asia and Africa. Malaysia, Thailand and Indonesia together command 95% share of the worls market.

Indonesia alone exported medical gloves at a value of US$ 200 millions in 2005. This is an increase of a wopping 20% over the 2004 figure!

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Medical golves from Guayule latex

Manufacturer:Can we use Guayule latex for making medical gloves? Is it really hypoallergenic in the long term? We heard that ASTM had approved Guayule latex for medical devices. Is that true?

JohnWoon:Yes, you can use Guayule latex for a wide range of latex products including medical gloves. This latex has been proven to have very low level of natural protein which is different from the allergenic protein you find in Hevea latex. Also, tests done so far have proven that latex products made from Guayule latex do not induce allergenic reaction to subjects who are already sensitive to Hevea latex products.

The question whether Guayule latex would still remain hypoallergenic and not result in eventual sensitisation to some individuals after prolonged usage and exposure remains a question. Only time could tell.

ASTM (The American Society for Testing and Materials) does not "approve" Guayule latex. What happened was they had approved a new Standard Specification to include Guayule latex (NRGL) as another alternative natural rubber latex to be used beside Hevea latex (NRL). Also, a specification of less than 200 micrograms of total protein per gram of dry weight of latex and no detectable proteins according to the ASTM standard for quantifying allergy-triggering proteins in latex are applicable to NRGL (not to NRL at this stage)

However the main concern from the market is its high cost and limited capacity at the present moment.

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An introduction to SMG - A world-class standard for medical gloves

Manufacturer: 1) We understand that Malaysia is the world leader in the technically specified natural rubber and renowned world wide for introducing the SMR (Standard Malaysian Rubber). Recently we were told that Malaysia had yet again made history by introducing similar standard for medical gloves. Please tell us more about the gloves.
2) We have some technical problems regarding the handling of off-spec latex concentrates we imported from South East Asia that had badly affected our glove production. Details have been given to you by our Technical Department. I appreciate your agreement not to publish this piece of work by you due to its confidential nature.

JohnWoon: I'm glad to note your interest in SMG program from Malaysia. For your benifit, I'm reproducing the following published article:

As the world's leader in medical gloves, Malaysia is committed to supplying gloves of an internationally high standard for safety and reliability. The introducion of the Standard Malaysian Glove (SMG) program is a joint effort by the Malaysian Rubber Board's Rubber Research Institute of Malaysia (RRIM) and the Malaysian Rubber Glove Manufacturers' Association (MARGMA)

The SMG program was developed in consultation with regulatory and standard setting bodies such as the U.S. Food and Drug Administration (FDA) and other relevant authorities.

The SMG program establishes standards not only for barrier performance, the single most important function of medical gloves, but also for protein and powder content, elements believed to cause allergic reactions in individuals sensitive to latex proteins.

The program applies to medical examination gloves, both powdered and powder-free. They are identified by a green logo for powder-free gloves and an orange logo for the lightly powdered variety.

However, SMG certified gloves can also be identified by the presence of the SMG logo, printed in dominant color of the dispenser box, with the type of gloves, powdered or powder-free, clearly indicated on the dispenser box.

SMG gloves are consistent in quality.

All SMG manufacturers must have a quality management system in accordance with ISO 9000-2000 or its equivalent.

SMG certification is carried out by the Rubber Research Institute of Malaysia. An independent Quality Inspectorate of the Malaysian Rubber Board (MRB) undertakes regular surveillance testing to provide oversight and to ensure quality compliance by SMG producers. The MRB Testing Laboratory is accredited to ISO/IEC 17025 and is fully equipped for testing SMG gloves.

By setting clearly defined specifications for barrier function, strength, elasticity, and protein and powder content that are in line with FDA and ASTM technical specifications, the SMG program provides users with gloves that are consistently superior in barrier protection with reduced risk of protein sensitization.

Additional information about the availability of SMG gloves can be found at http://www.smg-online.biz

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