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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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Send Your Enquiry and Orders To: woonsungliang@yahoo.com.sg

Problem Solving Through E-Mails with John Woon Latex Consultants Is Possible
可以通过电子邮件与JW乳胶顾问来解决问题

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Wednesday, February 25, 2009

Factors Affecting Latex Gel Strength

Manufacturer: In our process we need to maximize the gel strength of our latex compound in order to reduce our rejection rate. Please give us your advice and comment on the factors affecting the gel strength of latex. We are using both prevulcanized latex (PV) and post-vulcanisable latex compounds and calcium nitrate as our coagulant.

John Woon (Senior Latex Consultant): To begin, you need to realize the fact that the gel strength of an unvulcanised latex is generally superior to that of the compounded latex be it prevulcanised or post-vulcanisable. Hence the higher the dregree of cross-linking, the lower would be the gel strength. This means that a PV with lower modulus would give better gel strength compared to one with higher modulus.

Also, with a post-vulcanisable latex compound, one has to monitor the cure state carefully as too advance a cure would lead to lower gel strength and hence higher chances of cracking of the latex flim.

Gel strength is believed to be dependant on how readily the rubber particles could coalesce to form an integrated film.

Generally, the gel strength could be maximised by using the highest possible latex solid content with highest coagulant strength coupled with the shortest possible latex dwell time. However in practice, very short latex dwell time is some times difficult to achieve. Also, too short a latex dwell time would lead to uneven thickness of the latex film.

Other factors include the colloidal stability of the latex compound, especially the chemical stability which in turns depends on the level of ZnO, fixed alkali and other surfactants in the latex, not forgetting of course the former temperature. (As agreed, detailed remedial actions for maximum gel strength is omitted here)



Saturday, February 21, 2009

Xanthates as an Alternative to Dithiocarbamates and Thiazoles in Latex?

Manufacturer: We are manufacturing latex dipped products including gloves. Recently we've received feedback from the market that some of our customers are allergic to the residual dithiocarbamates and thiazole accelerators in our products. We've been advised to look into xanthates which we've never heard of or used before. Can you please give your comment and advice?

John Woon (Senior Latex Consultant): You could start by evaluating sodium isopropyl xanthate, zinc isopropyl xanthate and zinc butyl xanthate. The sodium salt is water soluble while the zinc salt is not. The soluble version is more active and gives a faster cure than the insoluble one. You could also use a combination of both.

Xanthates belong to the group of extremely fast ultra accelerators. Since they are very fast, one tends to get a narrower cure plateau and a lower cure temperature of 80 to 110ºC. You still need the usual level of ZnO.

The disadvantages of xanthate are the instability, being a very labile accelerator and the odour which can be objectional to some people.

Wednesday, February 04, 2009

How To Make Polychloroprene Softer

Manufacturer: We are manufacturing dipped products using Polychloroprene. Please advise how we could improve the softness and flexibility of the rubber especially at low ambient temperatures.

John Woon (Senior Latex Consultant): Polychloroprene is one of the few synthetic elastomers that has the closest tensile properties to that of Natural Rubber. To make it even softer, you could either use petroleum based plasticizers such as light naphthenic or paraffinic process oil or ester-type of plasticizers such as di-n-butyl phthalates.

Please take note that although the petroleum based plasticizers help in preventing crystallization of polychloroprene it offers little advantages in overcoming the stiffening effect at low temperatures. On the other hand, ester-type of plasticizers are more efficient in this respect.

However, since the market is now avoiding phthalates due to the perceived toxicity issue, you should also look into other non-phthalates plasticizer such as Hexamoll® DINCH from BASF. If you need more details, please click HERE.


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What has the bouncing ball to do with tyres?

Latex Gloves Educational Articles from the Malaysian Rubber Export Promotion Council

How do you select your medical gloves?

Rubber Chemicals: Carcinogenicity, Mutagenicity, Clastogenicity.

Why is Compression Set measurement important?

Assessment of Latex Stability

Joule Effect

Poor Flocking Quality Of Household Gloves

Creaming of Latex

What is Vulcanization?

History of Latex Dipped Products

Applications of Prevulcanized Latex

Defoamer Creating Havoc in Glove Factory

Problems With Milling Rubber Chemicals

Medical Gloves From Guayule Latex

Introduction to SMG Gloves

 

 

Click on The Following Links to Read More Articles:

[Advantages of Vulcanization] [Applications of PV Latex] [Bacteria and Latex] [Chemical Toxicity] [Cross-Linking Density] [Biodegradability] [Black Articles] [Blooming] [Bouncing Ball] [Compression Set] [Condoms] [Creaming] [Defoamer] [FDA] [Fatty Acid Soaps] [Flame Retardant] [Flocking] [Food Packaging] [Glove Demand] [Glove Selection] [Guayule Latex] [History of Gloves] [Joul Effect] [Latex Stability] [Latex Thread] [Milling Problem] [MREPC Articles] [Nano Polymer Particles] [Nano ZnO] [Polychloroprene] [REACH] [SMG] [Storage Hardening] [Vulcanization] [Vytex] [Yulex]

Disclaimer:
The information and data contained in this site are believed to be accurate and reliable. However it is the responsibility of the visitors and readers to satisfy themselves that the information is workable under their own processing conditions. Hence the owners of this site make no warranties concerning the suitability of the information given in this site.

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