Training Courses by John Woon Latex Consultants

Manufacturer: We understand you also conduct on-site training for latex factories. Can you let us know the content of your training materials?

John Woon (Senior Latex Consultant): I offer quite a varied training courses to engineers, chemists, technologists and technicians engaged in the latex and latex products industries. Among others, the following are some examples of the subjects:

1) NR latex properties (Including latex stability, importance of process controls by latex producers, how to overcome destabilization problems such coagulum, viscosity, etc)
2) Dipping Technology (Discussion covers all stages of dipping process for gloves, condoms, toy balloons, etc)
3) Faults and defect of gloves, their causes and recommended remedial actions
4) Antigen, allergen, protein
5) Milling of rubber chemicals (choice of dispersants, mechanism of grinding and selection of milling machines)
6) Nitrosamine in Rubber Products – How to overcome them?
7) Prevulcanised latex and Post-vulcanisable latex (Pros and Cons)
8) Stage-Gate Process For New Product Success (An R&D System)
9) Nitrile Latex
10) Polychloroprene Rubber
11) Adhesive technology
12) 6-Hat Thinking

For some of the PowerPoint slides I use, please visit this site  http://www.slideshare.net/johnwoon/john-woons-training-slides

How to Control Latex Creaming

Manufacturer: Lately we've been encountering uneven latex pick up and we have been advised that this could be due to latex creaming. What is latex creaming and what we could do to prevent it?


John Woon (Senior Latex and Rubber Consultant): The Specific Gravity (SG) of rubber is about 9.02 while that of the serum (water phase) is about 1.02. This means the rubber particles are lighter than the serum hence there is always a tendency of the rubber particles to rise to the top of the container, a process which is commonly known as “creaming”. 

If the latex is allowed to stand without agitation, over time (especially when exposed to elevated temperatures) a top creamy layer with high TSC and DRC would be formed. Fortunately this “cream” is readily re-dispersed into the other part of the latex with some stirring. Therefore, to minimize the incidence of creaming, latex in storage tanks (or any other containers including your compounding tanks) should be agitated periodically, for instance, once per day for 30 minutes at slow to medium speed. 

 For your latex dip tank, proper agitation must be attained to ensure maximum latex homogeneity without too much turbulence to cause the formation of air bubbles.

Analysis of Defective Balloons - Blotchiness

Manufacturer: Many thanks for your very comprehensive 40-page report on how to improve our latex compounding and dipping process for our toy balloons. We now encounter uneven patches on inflated balloons. Any ideas how to overcome this.

John Woon (Senior Latex and Rubber Consultant): I have in fact included this in my report to you under "Analysis of Defective Balloons - Blotchiness". I'm repeating it here again:

This could be due to dirty formers, poor wetting of the coagulant and slow drying of the coagulant after withdrawal from the coagulant tank.

Recommended remedial actions:
6.1.1) Ensure formers are properly cleaned. Please refer to earlier discussion on using alkali cleaners (Item 5.1).

6.1.2) Ensure freshly prepared coagulant is matured for at least 24 hours before use.

6.1.4) Ensure the formers are dried as soon as they are withdrawn from the coagulant tank by increasing the coagulant temperature. (See item 5.3.5)

6.1.5) Increase the level of ammonium or potassium caseinate.

Wetting Property of Coagulant

Manufacturer:

-->We are having great difficulty getting the surfactants to mix properly in the initial coagulant.

We are using GEP 70 (Calcium Nitrate Liquid), Water , Surfynol TG,  Surfynol 465 (Both from Air Products), Ca(CO3).

We are not getting good wetting which is causing voids in the latex dip (the latex is from Yulex).

Thank you for your assistance. Glad I found your blog !!

John Woon (Senior Latex and Rubber Consultant): Before blaming your coagulant mix, please carry out the simple test below to ascertain the latex itself is OK:

Dip a clean glass plate into the latex. Slowly withdrawal the plate from the latex and observe the latex coating on the plate. If the coating is even then you could proceed to look at your coagulant.

Assuming that the coagulant is in fact at fault, please replace Surfynol 465 with Teric 320. Do not use freshly prepared coagulant. It must be matured for at least 24 hours before use to ensure best wetting property during dipping.

Other technical details are in my report sent to you separately.

Hope this helps.