Natural Rubber price levels off

According to an article in Tyres & Accessories, "The price of natural rubber is finally starting to level off, after increasing 40 per cent in the last year. According to Deutsche Bank analysts, the price is now likely to level off at around US$2.8/kg, having risen to US$3.3/kg (RSS3 grade) by June 2008. “If natural rubber price follows recent drop of oil price, it could drop to US$2.6/kg (the average of the last 18 months)," the analysts observed. The news is likely to be greeted by a sigh of relief by tyre manufacturers who had been witnessing erosion in their operating profits due to increased raw material prices."

You are at the site for answers and solutions to all your problems in natural rubber latex processing and manufacturing of industrial, household and medical gloves, condoms, catheters, baby teats and baby pacifiers, toy balloons, latex foam products, latex threads etc.

Dipping problems of natural rubber latex catheter balloons

Latex Catheter Manufacturer: I am a process engineer for a medical device company. Our products include various types of catheters and we also make balloons for our own catheters. Recently, we are attempting to qualify a new latex mixture (post-vulcanised) from a new supplier for use on the manufacturing of balloons for catheters. We are successful for one batch of latex. The formers/mandrels are dipped in the coagulant (calcium nitrate + ethanol) for a while and allow to dry before dipping in latex vertically. However when we tried the same process for 2nd and 3rd batch of latex, we are unable to get the correct shape of the balloons using the same process. The following deviations were observed:

(1) Uneven latex pick up at the tips of the formers (see photo1)
(2) The balloon is much thinner at the sharp edge of the tip (see photo 2)

The latex from the 2nd and 3rd batch also seems to be more watery or less dense even though we did tried to control the viscosity to make sure that they are the same. Our supplier seems to lack the technical expertise to help us resolve this issue and claim that all their latex is within their spec. I somehow come across your website and is impressed by your passion and knowledge on latex technology as well as your willing in sharing invaluable information and knowledge. I hope you can advise us on the possible additive we may add to resolve this issue or spec of latex we should look into. Please revert back to me if more information is needed.

We also attached the latex test results and specification.

Hope to hear from you soon. Thanks.

John Woon (Senior Latex Consultant): You mentioned that you're using a post-vulcanised latex. Technically, there's no such thing as post "vulcanised" latex compound. I presume you meant post-vulcanisable latex.

If this is what you're using, I would recommend you try prevulcanised latex (i.e. PV latex) for more consistent processing properties.

Assuming all other factors being within your normal controls except the latex, the deviation of your product quality could be due to:

1) Inconsistent latex stability (e.g. MST, viscosity)
2) Inconsistent latex vulcanisation state. (I'm assuming you add the curatives to the latex yourself or your supplier supply the latex and chemicals for you to do the mixing)
3) The latex was not properly homogenised before use.

Other factors besides latex properties include:


1) Excessive collection of coagulant at the tip, especially when the former are not inverted or the inverting of the formers was delayed
2) Too fast withdrawal of formers from the latex. Ideally the speed of withdrawal should equal to the speed of the latex flowing downward.
3) Formers are too cold.
4) Dirty former tip
5) Excessive drainage of coagulant away from the tip, assuming you invert the formers after coagulant tip and the formers are not preheated.

I've checked your latex test report and found that the TSC (~57%) is unusually low if it is the standard centrifuged latex concentrate. Also, the pH (~12.0) is abnormally high.

The specification of your latex leaves a lot to be desired. If you really want to control and monitor your latex quality well, you should include all the following:

1) TSC
2) Alkalinity
3) MST
4) VFA number
5) KOH number
6) Viscosity
7) Total Magnesium content

Natural rubber latex could sometimes be difficult to handle because the inherent properties and hence the processibility might change with different batches of latex despite the various parameters being within the agreed specification. Also, there are "tricks" some producers could resort to in order to make a "bad" latex meeting your specification. You must therefore make a point to know who the producer is if you are now buying from a trader and check their background.

You are at the site for answers and solutions to all your problems in natural rubber latex processing and manufacturing of industrial, household and medical gloves, condoms, catheters, baby teats and baby pacifiers, toy balloons, latex foam products, latex threads etc.