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, April 18, 2017
Monday, April 10, 2017
Demoulding Problem of Latex Foam Products
John Woon (Senior Latex Consultant): All products made from rubbers or elastomers with some forms of moulding should be able to be removed from the moulds easily at the end of each cycle of moulding without undue stress being applied to the products. Your encounter of the demoulding problem could be due to poor cleaning process for the moulds and/or wrong choice of releasing agents.
I suggest you introduce a proper cleaning process to ensure that all surfaces of the moulds are free from the cumulative build-up of non-rubbers from the latex and compounding ingredients.
As for the releasing agents, you can try aqueous solution of sodium carboxymethyl cellulose or it's derivatives and low-molecular-weight polyethylene glycols. You can use either of these or a blend of both. This is best applied by spraying while the moulds are still hot.
Monday, March 27, 2017
JW Latex Consultant's New Website Launched!
You are welcome to check it out!
Monday, March 20, 2017
Why Does Dilution of Natural Rubber Latex Cause Latex Detabilisation?
John Woon (Senior Latex Consultant): If your latex compounds are well stabilised with sufficient soaps/stabilisers, dilution with water generally would improve the latex stability.
I believe your latex compounds are not properly stabilised and when water is added, the concentration of stabilisers present in the water phase is reduced, hence a reduction of latex stability leading to the formation of coagulum.
What you can do is to add some stabiliser (similar to that used in the latex) to the water before dilution.
Sunday, March 05, 2017
Second Edition of "Practical Latex Technology" Launched!
It contains answers to more than 150 questions plus other very useful tips and ideas!
For easy of reference, it is divided into 5 Parts:
Part 1: Vulcanisation
(Vulcanization), Vulcanisation of Latex and Prevulcanised Latex
Processing and Finished Products
and Processing Aids
Get your copy for a one-time investment of only $85.00!
Sunday, February 12, 2017
Thickeners for Natural Rubber Latex and Nitrile Latex
John Woon (Senior Latex Consultant): You can try the following:
1) Natural Colloids
Examples for theses are casein and alginate. Ammonium casienate (10% solution of casein in ammonium hydroxide) and sodium alginate (5 - 8% solution) have been used successfully in the industry. However, these are prone to bacterial attack. I suggest you add some bactericide.
Widely used cellulose types of thickeners include methyl cellulose, hydroxy propyl methyl cellulose and sodium carboxyl methy cellolose and their derivatives with chemical modifications. All are used at a concentration of 4 to 6%. They are available in different molecular weights giving different viscosity accordingly.
Examples are ammonium polyacrylate, sodium polyacrylate and polyacylate acid emulsion. When using the acid emulsion care must be taken to prevent possible flocculation of latex.
4) Water-soluble polyurethane
This is an alkyl phenol ethoxylates associative polyurethane thickener widely used in the coating industry.
Monday, January 23, 2017
Happy Chinese New Year!
Mr. John Woon of JW atex Consultants would like to send his visitors a beautiful Chinese New Year Card. Please view the card in the following link:
Sunday, January 22, 2017
How to Obtain Small Natural Rubber Particles for Textile Impregnation?
We have been told that in the normal centrifuged latex concentrates, the inherently smaller rubber particles of the latex have been removed by the centrifugation process. My question is how and where do we obtain such small sized rubber particles which are originally present in the latex?
John Woon (Senior Latex Consultant): Good question! Though it is possible it is costly to recover the small sized rubber particles from the skim after the centrifugation of field latex to obtain the concentrated latex.
Fortunately all is not lost because latex concentrates made by evaporation process are commercially available from Revertex Malaysia (Synthomer). In the evaporation process, only water is removed from the latex hence the inherently present small rubber particles are not removed, unlike the centrifuged latex.
Also, these evaporated latex concentrates have excellent mechanical and compounding stability besides having excellent penetrating property. They are available with 68% and 73% TSC.
How to Minimize Copper Staining While Maintening Dithiocarbamates in the Compound Fromulations
John Woon (Senior Latex Consultant): It is not easy to prevent copper staining without removing dithiocarbamates from your latex compound formulations. However, I have the following suggestion to control the staining:
1) Try reducing the level of dithiocarmate to the very minimal while adding a thiazole (ZMBT) as the main accelerator. The reduced level of dithiocarbamate is such that it still gives you reasonable rate of vulcanization and physical properties of the final products.
2) If you are using ZDEC, replace it with ZDBC as the latter has lesser tendency to cause migration staining.
As for heat resistance, you can try sulphur donors such as TMTD, DPTT or Morpholine disulphide in conjunction with thiazoles.
Thursday, December 29, 2016
How to Improve Setting of Latex in Straight Dipping?
John Woon (Senior Latex Consultant): Here are some tips you can evaluate:
1) The latex compound must be well matured before use. I'm assuming you are using post-vulcanisable latex compound.
2) Control the latex compound viscosity.
3) Make the latex slightly heat-sensitive by controlling the formation zinc-ammine complex with ZnO and alkali.
Sunday, December 11, 2016
How to Transfer Latex Without Latex Destabilisation Due to Mechanical Shear
John Woon (Senior Latex Consultant): One could transfer latex from one container to another by using pump, compressed air or gravity. While pumping might destabilize the latex, compressed air and gravity feeding have the least destabilization problem. When using pump, care should be taken to select one that gives the least mechanical shear to the latex.
For compressed air feeding, one must use pressure tested and insured tanks and a supply of clean compressed air. Therefore this more expensive method is mainly used for bulk deliveries of latex.
Transferring latex by gravity is the cheapest and simplest to use while preventing mechanical shear to the latex and therefore the chances of coagulum formation are kept to the very minimum. However the factory layout must be designed in such a way that the storage tanks are located on an upper floor or level to allow the latex to flow down to the compounding tanks situated at a floor lower. From the compounding tanks, the compounded latex is in turn allowed to flow to yet another floor lower for further processing such as dipping, casting or extrusion, etc.
Saturday, November 19, 2016
Natural Rubber Latex - Problem with Dilution with Water
John Woon (Senior Latex Consultant): One possible reason is the fact that when water is added to the latex compound, the concentration of latex stabiliser present in the water phase is reduced accordingly. Therefore you should add a small amount of the stabliser in the water before using it.
Also, you must prevent "pH shock" to the latex by adjusting the pH of the eater to about 9.50. It is advisable to use deionised or softened water for latex dilution to prevent destabilisation of latex by free calcium and magnesium ions.
Tuesday, October 25, 2016
Discoloration of Rubber Products
John Woon (Senior Latex Consultant): Discoloration is an unwanted and undesirable change of colour of light-coloured rubber products especially white toy balloons. However, it is very often confused and misunderstood by many latex products manufacturers.
Friday, October 21, 2016
John Woon (Senior Latex Consultant):
Please be informed that our sister website, JWLatexConsultants.com has been hacked and infected. For your security, please do not visit this site for the time being. We apologize for any inconvenience caused.
You are welcome to visit our sister website at http://woonsungliang.wix.com/jw-latex-consultants
Wednesday, September 28, 2016
Natural Rubber Latex Adhesives vs Solvent Based Adhesives
John Woon (Senior Latex Consultant): Generally, while latex based adhesives are environmentally friendly, it also offers the following advantages over the solvent based adhesives:
1) Latex has a low viscosity at high solid content. For instance, NR latex concentrate with a total solid content of about 60% has a viscosity of only 150 to 200 mPa.s whereas a rubber solution of about 17% has a viscosity of 60,000 to 100,000 mPa.s.
2) The low viscosity of latex allows it to be easily applied by spraying and roller coating.
3) The high solid content of latex allows for high coating weight (dry) to be achieved with minimal number of coating.
4) For solvent based adhesives the rubber is frequently masticated to breakdown of the rubber molecules before use to ease dissolution in solvents. This results in the weakening of the cohesion strength of the adhesives. Latex based adhesives do not have this problem.
5) Owing to the absence of solvent, latex adhesives do not pose as health and fire hazards. There is no need for expensive procedures and precautionary actions such as the use of flame-proof motors, maximum ventilation, flame-proof lighting and segregation from other production processes.