The latex doctorSSflTI LH.Y F Bader

Ozone attack - Examglove compound -

Balloon colour

Mr. Harry F.Bader, Vice-President,LatexServices,AkronRubberDevelopmentLaboratory inAkron, USA,and a worldauthority onlatex, answersquestionsand doubtsofreaderson latexand latexproducts.

Send your questions to:

‘The Latex Doctor’Rubber Asia,Dhanarn House,Cochin - 682 -020,Kerala, India Fax: 94-484-317872

I n the July-August issueof RubberAsiayou have mentioned

that ozone attack in latexgloves can he from sunlight orfactory fluorescent lighting.What would be the averageozoneconcentration in the atmospherein the vicinity of the fluorescent tubing? Would you recommend switching over to otherlighting systemsIn rubber/latexfactories and storage areas toovercome the possibilities ofozoneattack?

Bhimrajka Impex LtdMumbai

I havenevermeasuredtheozoneconcentrationunder fluorescentlighting. However, I haveoftenexperiencedozone cracking ofgloves on the lop layer of toteboxesleftuncoveredunderfactorylights.

A medicaldevicemanufacturerin California foundthe ozonelevelin its manufacturingassemblyareato be 5PPhm.They havefluorescent light as well as potentialozone sourcesfrom motors andswitchgear. Ozonecrackingwaspresentin their devices.

Temporary storage containersshould always haveopaquecoversandlatex productsshould notremain on the work table overnight.

1 would not recommendchanging from fluorescent lighting.It is easier and less expensiveto provide covers for tote boxesand other temporary storagecontainers.

O urs is a small-scaleunit manufacturing latex foam

products. We are the suppliers

to major coachbuilders in TamilNadu. Our products are goodinquality and are competitive. Butof late we see that the competitors are ready to supply atheavily reducedprices with goodquality. We are told that theyare following non-deammoniating process and using somelatest trend in foam technology.We want to update our technology. Could you please arrangefor that?

Ahammed NazeerMNK Industrial ProductsLtd.

haveno experiencewith usingammoniapreservedlatexfor foamlatexproductswithout deanunoniation. However, making foamlatexproductswith latexpreservedwith materialsother than ammonia has been done for over 45years. Natural latex preservedusing Monsanto "Santobrite" becameavailablein the 1950’s. TheInternational Latex Corporationbegan making pillows withSantobritepreservedlatexin 1952.Therewasno majorchangein therecipe, thestabilizersystem,or inthe amount of 5SF required forgellation. This latex wasuseduntil 1.L.C. shut down its pillowoperation in the late 1950’s.

Non-ammoniapreservedlatex isavai]abletoday. It is unlikely that"Santobrite" is still usedsince itis a suspectedcarcinogen.I suggest that you get non-ammoniapreservedlatex from your latexsupplier.

We understand that the useof Hevea plus M.G. latex

in the production of foam rubber will improve its hardness.

RubberAsia U January . February 2000 65

fl Kindly inform us as to how thiscould be usedand the name ofmanufacturers of this chemical.

MG. latex is acrylic latex andmany arecompatiblewith NR latex andwould provide stiffness.

I contactedB.F. Goodrichandwas told that their productnumbers 26091, 26106, and 26391would possibly perfrom satisfactorily. theyhad no experienceregattling thepercentageof addition,cure systemsor stabilizersystemsthat would possibly be needed.

The idea seemssound. However, it would requiresomecompounddevelopmentwork to arriveat theproperrecipeto achievethedesiredstiffnessalongwith goodprocessability.

High stryeme 58k such asRovene4106 from Mallard CreekPolymers a subsidiary ofAmeripol Synpol could alsoperform as a stiffener. Their technical servicefax is 704-547-8849.

I am a regular subscriber to your magazine, and running a

household glove manufacturingplant in Sri Lanka. We are nowin the process of setting up aplant to produce exam gloves.Doyou know how I could get standard timing for each station,such as coagulant, glove compound and so on, for exanlination gloves?

Dr. GunawardanaColombo

The latex compound could bevirtually thesameas your household glovecompound.Removethecolourandthe titanium dioxide orclay; reduce the % TSC and itshouldbe quite satisfactory.

The coagulantstrengthwould bereducedso the latexpick-upwouldbe as requiredfor anexaminationglove.

As to thedippingspeedsandtiming, they arevery muchdependenton the designof your equipment.For example a single continuouschain would move much morespeedilythan a travelling bar system. The vertical speedsare dependenton the designof your dipping forms. Some forms permitfaster vertical in speedswithout

GeorgeL. MathewDuroflex Ltd.

trappingair in thefinger crotches.Others must go into the latexmuchmore slowly.

Somemachinedesignsareeasily converted from householdgloves to exam glovesby changing thecoagulantstrengthandthelatex % total solids. However, thatversatility usually will not allowyou to achievetheoptimumproductivity thatcanbeobtainedfroma machine specifically designedfor examinationgloves.

In short, I couldn’t beginto giveyou specific times,speeds,coagulantconcentrations,latex % TSC,etc without first having the machinedefined. Even with that information dipping experimentswill berequiredto give to balancebetweencoagulantconcentration,latex % TSC anddwell time.

W e are balloon manufacturers at Madurai. We are

facing the colour shining problem. We expect your valuableadvice for our balloon qualityimprovement,1. We blow the balloon at night

time. The colour sliming ismore than 5 to 6 hours.

2. We blow the same batch ofballoons, and put them insunlight, and the colour shining is reduced within tenminutes,

Which chemical or oil is suitable for our balloon maintaining colour shining during sunlight?

Shri Krishna Rubber ProductMadurai

The dulling of balloon colour insunlight can be helped to someextentby coatingtheballoonwitha very dilute solution of siliconemulsion 2% or less, such asunioncarbideLE36.

The dulling is essentiallyozoneattack.A goodantioxidantwill also help.BUT andA02246areusedby someballoonmanufacturers.

p lease find enclosed6 nos.lightly powdered latex ex

amination glovesproducedin 2of our dipping lines, As indicated on these gloves, we areexperiencing a defect brownishcoloured stain which tends toarise from the formers after running the dipping lines from 4 to5 days.

Data with regard to the dipping lines are:

TSC% 32-325 Latex 4-5%Powder

CaNo3 conc. In coagulant gJlit 40-50

Caco 3 cone In coagulant gIlit 40-55.

Acid 11N03 washing online 1.86% 20-30x.01

Hot water tank temp. deg.cent.90-95

Leaching tank temp. deg.cent.88-92

Oven temps. Range curing &drying deg. cent. 80-120

Latex dipping tanktenip.deg.cent25

Coagulant dipping tanktemp.deg.cent65-70

This stain is causing a fewproblems with our productionprocess and quality. Pleaseadvise.

Rosban Gooneratne1-janwellaRubberProducts

Colombo

The "stains" on the samplegloves are rubbed off withoutmucheffort, which indicatestheyareattachedto the glove surfacerather thanbeing an actual staining of the latex film. Also the"stain" is on theinsideas dipped.

That plus the fact that they occur after4-5 daysof runningtheline, points to a dirty form issue.Possibilitiesare:

* The acid tank is accumulatinganoily scumon the liquid surface. Thescumis clinging to theforms and is not being completely removed in the hotwater.

* The scum is on the surfaceofthe hot water rinse tank and isclinging to the forms as theycomefrom the rinse.

* The acidhasbecomeweakandis not dissolving the build-upentirely.

* A possiblebut lesslikely sourceof theproblem could be an accumulationof dirt in thedryingareasafter the form rinsebutbefore thelatex dip.

I hope the above will help inyour investigation.

66 RubberAsla U January - February 2W