JW Latex Consultants (and Rubber Consultants,乳胶顾问) offer solutions to your problems in Natural Rubber latex and Synthetic Rubber latex processing and the manufacturing of latex products (condoms, catheters, medical gloves, baby teats and soothers, toy balloons etc) Quick answers through e-mails are possible at reasonable cost.
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Tuesday, July 26, 2016
JWLatexConsultants.com Hacked and Infected!!
John Woon (Senior Latex Consultant): Please be informed that our sister website, JWLatexConsultants.com has been hacked and infected. Please do not visit this site for the time being. We apologize for any inconvenience caused.
Instead, please visit http://woonsungliang.wix.com/jw-latex-consultants
Monday, June 27, 2016
Sodium Soaps vs Potassium Soaps as Latex Stabilisers
Manufacturer: We use both KOH and NaOH for making our fatty acid soaps as stabilizers for our latex compounds. We are experiencing more problem with sodium soaps especially when there is a change in ambient temperatures. Why?
John Woon (Senior Latex Consultant): Simple. The reasons are as follows:
1) Sodium soaps are less soluble than potassium soaps.
2) Sodium soaps are harder than potassium soaps.
3) Sodium soaps tend to gel at lower temperatures although this phenomenon is reversible.
Therefore from technical point of view, there is no reason why you should use sodium hydroxide although it might be cheaper than potassium hydroxide.
Monday, June 06, 2016
Blowing Agent (Foaming agent) for PVC Plastisol
John Woon (Senior Latex Consultant): Some of the most common blowing agents used for rubber and plastic do have high decomposition temperatures of more than 150°C which would of course not work satisfactorily if your processing temperature is only 120°C.
I suggest you evaluate the following:
Azo nitriles, bezene sulphonic acid hydrazide and ditroso pentamethylene tetramine.
Let me know the outcome in due course.
Thursday, May 26, 2016
Wetting Agent in Coagulant
John Woon (Senior Latex Consultant): You need to pay attention on the following factors:
1) Temperature of the coagulant should be as high as possible but not exceeding the could point or 65°C to achieve maximum wetting.
2) Level of wetting agent is to be high enough but not to the extent of causing foaming and retarding drying.
3) You should determine the could point on your own instead of just relying on surfactant suppliers' cloud points because salts such as calcium nitrate and other ingredients in the coagulant mix can affect the cloud point.
Details has been sent to you separately at your request.
Thursday, May 19, 2016
Reducing Ammonia Content of Latex Concentrate with Formaldehyde
You can try Emulvin W or equivalents as the surfactant. If you continue to encounter stability problem such as viscosity rise it could be due to the latex quality problem, in which case I suggest you remove the ammonia by stirring with a fan over the surface of the latex.
Thursday, April 21, 2016
Curatives for the Vulcanisation of Nitril Rubber
John Woon (Senior Latex Consultant): For general applications, you can used practically the cure systems for both NR and SBR such as thiazoles and sulphenamide cure system. For high temperature applications and also where low compression set is required, both thiuram and peroxide cure systems should be used.
You should also get the advice from the rubber suppliers or manufactueres because the following factors involved in polymerization, etc. are also affecting the vulcanisation of nitrile rubber:
2) Emulsifiers and surfactants
3) Polymerization additives
4) Polymer rheology
5) Process aids in polymerization
Friday, April 08, 2016
Blending of Different Latices and Addition of Fillers in Latex Adhesive Compounds
John Woon (Senior Latex Consultant): I suggest you look into the following points:
1) Blending of two different latices (latexes)
1.1) Make sure the pH of both latices are as close as possible. By changing the latex pH, the latex could sometimes be destabilized in which case, it is advisable to add a non-ionic surfactant to that latex before the pH adjustment.
1.2) Latex with smaller particle size would tend to rob the surfactant already present on the particles of latex with higher particle size. Generally, the level of surfactants required for the blend is more than the total amount required for the two individual latex.
2) Filler addition
2.1) You could either add the filler dry or as a pre-prepared slurry to the latex. The former would require higher level of surfactant than the latter.
2.2) The higher the level of filler, the higher is the level of surfactant required.
2.3) Filler with smaller particle size would tend to rob more of the surfactant from the latex particles compared to filler with coarser particles.
2.4) Filler type is important e.g. clay and talc would have less destabilizing effect on the latex compared to calcium carbonate.
2.5) Generally a combination of surfactants performs better than a single surfactant.
Hope this helps.
Tuesday, March 15, 2016
Mechanism of the Leaching Process
John Woon (Senior Latex Consultant): Over the years I've studied and analyzed the factors involved in the leaching process so as to achieve the most optimized leaching effectiveness for a variety of dipped products.
I've identified 7 steps which take place in sequence during leaching. I've sent this along with some details of each step to you separately. Please let me know if this is of any help.
Working Off of Old Latex Compounds
John Woon (Senior Latex Consultant): Beware of possible problems when using old latex compounds especially when it has already “over-cured” as it would lead to low elongation at break, high modulus and poor tensile strength and hence premature tearing.