methocel cellulose ethers- technical handbook

7/27/2019 Methocel Cellulose Ethers- Technical Handbook

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METHOCEL Cellulose Ethers

Techn

icalHa

ndbook

Technical Handbook


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1

* Trademark of The Dow Chemical Company

METHOCEL* cellulose ethers arewater-soluble polymers derivedfrom cellulose, the most abundantpolymer in nature. For over 50years these versatile productshave played an important role infoods, cosmetics, pharmaceuticals,latex paints, constructionproducts, ceramics, and a hostof other applications.

METHOCEL products are used asthickeners, binders, film formers,and water-retention agents. Theyalso function as suspension aids,surfactants, lubricants, protectivecolloids, and emulsifiers. In addition,

solutions of METHOCEL thermallygel, a unique property that plays akey role in a surprising variety ofapplications. You wont find thisvaluable combination of propertiesin any other water-soluble polymer.

Multifunctionality and EfficiencyImprove Formulation Economy

The fact that so many usefulproperties are simultaneouslypresent and often act incombination can be a significant

economic advantage. In manyapplications, two, three, or moreingredients would be required todo the same job performed by asingle METHOCEL product. Inaddition, METHOCEL celluloseethers are highly efficient, oftenyielding optimum performanceat a lower concentration thanthat required with other water-soluble polymers.

Range of Products OffersFormulating Versatility

The broad range of METHOCELproducts available is certainly onereason theyve been used successfullyin so many different applications.There are two different chemicaltypes and each is available indifferent grades, physical forms, andviscosities. By choosing a specificMETHOCEL product, its possible

to obtain the optimum degree ofthickening, binding, moistureretention, and other propertiesdesired in a given formulation.

Premium and Food Grades forFood and Drug Applications

METHOCEL Premium and Foodproducts have long been used bythe food and drug industries. Bothmethylcellulose and hydroxypropylmethylcellulose are recognized asacceptable food additives by theU.S. Food and Drug Administration(FDA) and are listed in the FoodChemicals Codex and theInternational Codex Alimentarius.Both are included in the UnitedStates Pharmacopoeia (USP XXI).Methylcellulose is consideredGenerally Recognized As Safe(GRAS) by the FDA.

Standard Grades for OtherApplications

Standard grade METHOCELproducts have the same performanceproperties as Premium grades.The major difference is that

Standard grades can have slightlyhigher levels of impurities. Standardgrades are not approved for use infoods, although some Standardgrade products may be used ascomponents of containers comingin contact with food (indirectfood additive).

Viscosity Gradesfrom 3 to 100,000 mPas

METHOCEL cellulose etherproducts are available in various

viscosity grades, ranging from 3 toover 200,000 mPas. Because theviscosity of a solution depends onthe concentration of METHOCEL,this wide range of product viscosityallows you to obtain the viscosityyou want in a formulation, whileusing a concentration that givesthe desired level of otherperformance properties.

Available as Powders,Surface-treated Powders, andin Granular Form

For further formulating versatility,METHOCEL products are availablein three different forms: powder,surface-treated powder, and granular.The form influences the techniquesused in making solutions. Untreatedpowders are soluble in cold water,but must be thoroughly dispersedbefore they begin to dissolve.Surface-treated powders and granularproducts can be added directly toaqueous systems. The dissolution ofthese products can be controlled by

a shift in pH.

Techniques commonly used inpreparing solutions with differentphysical forms of METHOCELproducts are summarized onpages 1114 of this handbook.

Key to Product Nomenclature forMETHOCEL Products

METHOCEL is a trademark ofThe Dow Chemical Company for aline of cellulose ether products. An

initial letter identifies the type ofcellulose ether. A identifiesmethylcellulose products. E, F,J, and K identify differenthydroxypropyl methylcelluloseproducts.

The number that follows identifiesthe viscosity in millipascal-seconds(mPas) of that product measured at2% concentration in water at 20C.In designating viscosity, the letterC is frequently used to represent100 and the letter M is used to

represent 1,000.

Several different suffixes are alsoused to identify special products.P is sometimes used to identifyMETHOCEL Premium gradeproducts. LV refers to speciallow viscosity products. Gidentifies granular products.The letter S identifies

An Introduction to METHOCEL Cellulose Ethers

Note: mPa.s (millipascal-seconds) is equivalent to centipoise. All solution viscosities are measuredwith Ubbelohde viscometers at 2% concentration in water at 20C (68F).


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surface-treated products, CRdenotes a controlled-release grade,and FG identifies food grade.Developmental grades are denotedby the letter X plus a secondletter (usually U or Y) plus a five-digit code.

There are also a number of special-purpose METHOCEL productsdeveloped for cosmetics,pharmaceuticals, ceramics, andother applications which havedifferent systems of nomenclature.For example, METHOCEL 40-Series products make up a familyof special surface-treated products

for cosmetic formulations.

Example A: METHOCEL A4CPremium is the designation for aPremium grade methylcelluloseproduct having a viscosity of400 mPas.

Example B: METHOCEL J5MSis a Standard grade hydroxypropylmethylcellulose product with aviscosity of 5,000 mPas, whichhas been surface-treated foreasy dispersion.

How to Get Started Formulatingwith METHOCEL

To completely evaluate howMETHOCEL cellulose ethers canimprove quality, performance, andeconomy in your formulations,youll want to try them in yourown lab. Whether you aredeveloping an entirely new productor working to improve an existingone, chances are youll find aMETHOCEL product thats

ideally suited to your needs.

Free Samples and LiteratureAvailable

Sample quantities of METHOCEL

products are available free ofcharge for your developmentalwork. You can obtain samples bycalling one of the numbers listedon the back cover of this brochure.Literature covering the use ofMETHOCEL products in many ofthe applications listed on pages 79of this handbook is also availableon request. Just tell us what typesof formulations or products youare evaluating, and well sendyou all the current literature that

applies. Or visit our website atwww.methocel.com for a completeselection of downloadable literature.

Our Technical Service andDevelopment Staff Can Help

Talking with someone on ourTechnical Service and Development(TS&D) staff can save you a greatdeal of formulation time. In certainapplications, a blend of METHOCELproducts may give the best results,and the details may have already

been worked out by someone inour lab. We have technical personnelwho specialize in foods, ceramics,paints, cosmetics, pharmaceuticals,construction products, and otherspecific uses for METHOCELproducts. By taking advantage oftheir experience with METHOCEL,youll get a head start with yourformulation and be certain ofgetting the most out of theseversatile products.

Contact Us Today!

Again, if you would like samples,additional literature, or technical

assistance, dont hesitate to call.Our numbers are listed on theback cover of this brochure. Calltoday. The sooner you get startedformulating with METHOCEL,the sooner youll start seeingimproved performance andeconomy in your products.Our website also containsvaluable information to assistyou in learning more aboutMETHOCEL.

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General Properties of METHOCEL Cellulose Ethers

General properties common to thewhole family of METHOCELcellulose ether products are listedbelow. Individual METHOCELproducts exhibit these propertiesto varying degrees and may haveadditional properties that aredesirable for specific applications.Detailed information on theperformance properties ofMETHOCEL products can befound on pages 1521.

Water solubility. METHOCELcellulose ethers dissolve in waterwith no sharp solubility limit.

Surface-treated and granularMETHOCEL products can beadded directly to aqueous systems.This feature provides exceptionalhandling flexibility and control ofsolubilization rate. Althoughuntreated METHOCEL powders aresoluble in cold water, they must firstbe thoroughly dispersed in the waterto prevent lumping. Dispersiontechniques are described on pages1113. The maximum concentrationis limited only by solution viscosity.

Organic solubility. Certain types andgrades of METHOCEL celluloseethers are also soluble in binaryorganic and organic solvent/watersystems, providing a uniquecombination of organic solubilityand water solubility.

No ionic charge. METHOCELcellulose ethers are nonionic andwill not complex with metallic salts

or other ionic species to forminsoluble precipitates.

Thermal gelation. Aqueous solutionsof METHOCEL products gelwhen heated above a particulartemperature, providing controllablequick-set properties. Unlike gelsformed by protein thickeners,the gels go back into solutionupon cooling.

Surface activity. METHOCELproducts act as surfactants inaqueous solutions to provideemulsification, protective colloidaction, and phase stabilization.Surface tensions range from 42 to64 mN/m. The surface tension ofwater is 72 mN/m; a typicalsurfactant has a surface tensionof 30 mN/m.

Metabolic inertness. Used as foodand drug additives, METHOCELproducts do not add calories tothe diet.

Enzyme resistance. Enzyme-resistant METHOCEL productsprovide excellent viscosity stabilityduring long-term storage.

Low taste and odor. METHOCELcellulose ethers have excellent (low)flavor and aroma properties,which is important in food andpharmaceutical applications.

pH stability. METHOCEL cellulose

ethers are stable over a pH range of2.0 to 13.0.

Water retention. METHOCELcellulose ethers are highly efficientwater-retention agents. This isvaluable in food products, ceramics,coatings on adsorbent constructionsubstrates, and many otherapplications.

Thickening. METHOCEL cellulose

ethers thicken both aqueous andnonaqueous systems. The viscosityis related to the molecular weight,chemical type, and concentration ofthe specific METHOCEL product.

Film formation. METHOCELproducts form clear, tough, flexiblefilms that are excellent barriers tooils and greases. In foodapplications, this property is often

used to retain moisture and preventoil absorption during cooking.

Binding. METHOCEL celluloseethers are used as high-performancebinders for pigments, paper, tobaccoproducts, structured foods,pharmaceutical products,and ceramics.

Lubrication. METHOCEL productsare used to reduce friction in rubber,cement, and ceramic extrusions.They are also used to improvepumpability of concrete and sprayplasters, such as stucco, and in

food applications as lubricity aidsin extrusion and otherforming processes.

Suspending. METHOCEL productsare used to control settling of solidparticles, for example, herbs andspices in salad dressings, solidsin ceramic slips, and antacidsuspensions.

Protective colloidal action.

METHOCEL products are used toprevent droplets and particles fromcoalescing or agglomerating.

Emulsification. METHOCELcellulose ethers stabilize emulsionsby reducing surface and interfacialtensions and by thickening theaqueous phase.

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Nonaqueous Solvent Solubility

In general, binary solvent systemsfunction more effectively withMETHOCEL products than single

solvents. Where alcohols comprisepart of the binary solvent, solubilityimproves as the molecular weightof the alcohol decreases. Table 1lists several compounds which aretypical of the types of solventsthat can be used with certainMETHOCEL celluloseether products.

Table 1: Typical Nonaqueous Solvents Usedwith METHOCEL Cellulose Ethers

Furfuryl alcohol

Dimethyl formamide

Dimethyl sulfoxide

Methyl salicylate Propylene carbonate

Formic acid

Glacial acetic acid

Pyridine

Mixtures of methylene chloride and

ethyl, methyl, or isopropyl alcohols

Mixtures of chloroform and methanol

or ethanol

N-Methyl pyrrolidone

Solvent Solubility at ElevatedTemperatures

METHOCEL E and METHOCEL Jcellulose ether products possess

structures that provide unusualsolubility properties. They aresoluble in certain nonaqueous mediaat elevated temperatures, permittingthe formulation of mixes which canbe fabricated by techniques ofextrusion, hot-melt casting, andinjection and compression molding.Examples of suitable hot solventsare found in Table 2.

METHOCEL 310 Series Products

METHOCEL 310 Series productsare granular, high-viscosity materials(Table 3) that are sold only inEurope at this time. Controlledgranulometry provides good dry-flow properties, low dust formation,and lump-free dispersibility inwater as well as organic solvents.Their carefully balanced level ofsubstitution renders them solublein both water and certain organicsolvents or blends of solvents(Table 4). METHOCEL 310

cellulose ether products can beadded directly to any solvent orblend of solvents under normalagitation. When using solvent blendsthere is no need to pre-disperse theproduct in a non-solvent or low-solvent component.

SolventBoiling Point

CSolubility Point

CDegree ofSolubilitya

GlycolsEthylene glycol 197.3 158 CDiethylene glycol 244.8 135 CPropylene glycol 188.2 140 C1,3-Propanediol 214 120 CGlycerine 290 260 PDOWANOL* EE ethylene 134.7 120 C

glycol, ethyl etherDOWANOL TPM 242.4 160 Ptripropylene glycol,

methyl etherEsters

Ethyl glycolate 160 110 CGlyceryl monoacetate (Acetin) 127 100 C

at 4 mbarGlyceryl diacetate (Diacetin) 123133 100 C

at 5 mbarAmines

Monoethanolamine 170172 120 CDiethanolamine 268269 180 C

Table 2: Representative Solvents for METHOCEL E and METHOCEL J Cellulose Ether Productsat Elevated Temperatures

*Trademark of The Dow Chemical Companya C= completely soluble; P= partially soluble


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Physical Form Slightly off-white granules

Table 3: Typical Properties for METHOCEL 310 Cellulose Ether

Solution Appearance

Clear, Hazy,Smooth Structured Swellable Insoluble

Ethanol (EtOH)

Methanol (MeOH)

Ethanol/H2O 40/60

Methanol/H2O 40/60

Methylene chloride (MeCl2)

MeCl2/EtOH 84/16

MeCl2/MeOH 84/16

Tetrahydrofuran (THF)

THF/H2O 90/10-80/20

Isopropanol

Isopropanol/H2O 90/10-60/40

Isopropanol/MeCl2

1,1,1-Trichloroethane

Polypropylene glycol

Polypropylene glycol/H2O 70/30 delayed thickening

Butylglycol

Butylglycol/H2O 50/50

Dioxane

Acetone

CELLOSOLVE

Dimethylformamide

DOWANOL PM

Solvents

Solvent Type after 1 hour after 24 hours

in methanol (MeOH) 500 mPa.s 650 mPa.s

in ethanol (EtOH) 600 mPa.s 900 mPa.s

in methylene chloride (MeCl2) 7,500 mPa.s 10,000 mPa.s

Moisture (as packaged) max. 8%

Sodium chloride max. 1.5%

Particle size ca. 100-500 micron

Nominal viscosity1% Brookfield RVT,

RT, 20 rpm

Table 4: Some Typical Solvents and Solvent Blends for METHOCEL 310 Cellulose Ether


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Chemistry of METHOCELCellulose Ethers

METHOCEL cellulose etherproducts are available in two basictypes: methylcellulose andhydroxypropyl methylcellulose.

Both types of METHOCEL have thepolymeric backbone of cellulose, anatural carbohydrate that containsa basic repeating structure ofanhydroglucose units (Figure 1).During the manufacture of celluloseethers, cellulose fibers are heatedwith a caustic solution which in turnis treated with methyl chloride,yielding the methyl ether of cellulose.The fibrous reaction product ispurified and ground to a fine,uniform powder.

Methylcellulose is made usingonly methyl chloride. These areMETHOCEL A brand products.For hydroxypropyl methylcelluloseproducts (METHOCEL E, F, J, andK brand products), propyleneoxide is used in addition to methylchloride to obtain hydroxypropylsubstitution on the anhydroglucoseunits. This substituent group,OCH2CH(OH)CH3, containsa secondary hydroxyl on the

number two carbon and may alsobe considered to form a propyleneglycol ether of cellulose. Theseproducts possess varying ratiosof hydroxypropyl and methylsubstitution, a factor whichinfluences organic solubility and thethermal gelation temperature ofaqueous solutions.

There are also special-gradeMETHOCEL products availablethat have been formulated tomeet the requirements of specificindustries.

Degree of Substitution

The amount of substituent groupson the anhydroglucose units ofcellulose can be designated by weightpercent or by the average numberof substituent groups attached tothe ring, a concept known tocellulose chemists as degree ofsubstitution (D.S.).

If all three available positions oneach unit are substituted, the D.S. isdesignated as 3; if an average of twoon each ring are reacted, the D.S. isdesignated as 2, etc.

The number of substituent groupson the ring determines theproperties of the various products.METHOCEL A cellulose ethercontains 27.5 to 31.5% methoxyl,or a methoxyl D.S. of 1.64 to 1.92,a range that yields maximum watersolubility. A lower degree ofsubstitution gives products havinglower water solubility, leading toproducts that are only soluble incaustic solutions.

Higher degrees of substitutionproduce methylcellulose productsthat are soluble only inorganic solvents.

In the METHOCEL E,METHOCEL F, and METHOCELK cellulose ether products, themethoxyl substitution is still themajor constituent (Table 5). Themolar substitution (MS) reports thenumber of moles of hydroxypropylgroups per mole of anhydroglucose.In the METHOCEL J and 310-Series products, the hydroxypropylsubstitution is about 50% of thetotal substitution.

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HO

HOH

H

H

CH2O

CH3

H

O

O

CH3 H

O

H

OH

H

O

H

CH2

O

CH3

CH3

H

HO

HO

H

H

H

CH2O

CH3

HO

O

H3C H

O

OH

n-2

HO

HO

H

H

H

CH2

O

CH2CHCH3

H

O

O

CH3

OOH

H

O

H

CH2

O

CH3

CH3

H

HO

HO

H

H

H

CH2

O

CH3

HO

H

O

OH

n-2OH

CH3CHCH2

O

HO

Hydroxypropyl MethylcelluloseMETHOCEL E, METHOCEL F, METHOCEL J, and METHOCEL K brand products

MethylcelluloseMETHOCEL A brand products

ProductMethoxyl Degree

of SubstitutionMethoxyl

%Hydroxypropyl

Molar SubstitutionHydroxypropyl

%

METHOCEL A 1.8 30

METHOCEL E 1.9 29 0.23 8.5

METHOCEL F 1.8 28 0.13 5.0

METHOCEL J 1.3 18 0.82 27

METHOCEL K 1.4 22 0.21 8.1

METHOCEL 2.0 25 0.8 25310 Series

Table 5: Degree of Substitution for METHOCEL Products

Figure 1: Typical Chemical Structures of METHOCEL Products


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The diverse products and processeslisted here all have one thing incommon: All benefit significantlyfrom remarkably small concentrationsof METHOCEL cellulose ethers.In most cases, the major benefitsare improved physical properties,but in many applications there areimprovements in processing efficiencyand overall economy as well.

For more detailed information onany of these applications, contactone of the numbers listed on theback cover of this brochure or visitour website at www.methocel.com.

Adhesives

Carpet backsizing compounds.

METHOCEL products impartexcellent foaming characteristicsor pan froth to backsizingcompounds. This helps keep theadhesive in the glue line instead ofsoaking into the backing materials.Also, due to thermal gelation,adhesives set quickly and dry fasterat elevated temperatures.

Leather processing adhesives.METHOCEL cellulose ethers areused to paste hides to smoothporcelain or glass surfaces in leatherdrying processes. Because of itswater retention efficiency andthermal gelation, METHOCEL ismuch more effective than starch-based pastes.

Plywood laminating adhesives.

METHOCEL products are usedin plywood laminating adhesivesto control viscosity in glues forplywood manufacture. Thermalgelation and thickening propertiesof METHOCEL products keepthe adhesive from soaking intothe wood.

Cigar and cigarette adhesives.

Safe and efficient, METHOCELproducts have long been used asbinders for reconstituted tobaccosheets and as adhesives for cigar andcigarette manufacture.

Wallpaper pastes. Used as theprimary adhesive in dry mixes,METHOCEL cellulose etherprovides the wet tack required tohold a variety of paper types on thewall, yet has excellent slip propertiesso patterns can easily be matched.In premixed pastes, METHOCELis used to control viscosity andimprove wet tack. Pastes made withMETHOCEL cellulose ethers areeasily cleaned up with water anddont provide a source ofnourishment for insects.

Latex adhesives. METHOCELproducts are used as thickeners in

a variety of latex adhesives, such asadhesives used in shoe manufacturing.Fast drying speeds and highwet-tack strength due to thermalgelation are key benefits in manyof these applications.

Agricultural Chemicals

Dispersing agents. METHOCELcellulose ethers are used as suspendingand dispersing aids for wettablepesticide and fertilizer powders.

They provide high wet tack andadhesion to waxy plant surfaces.Chemically inert and nonionic,METHOCEL cellulose ether iscompatible with a wide range ofactive ingredients.

Spray adherents. Spray adherentsor seed stickers made withMETHOCEL products effectivelybind pesticides, inoculants, andnutrients to seeds. METHOCELproducts feature low plant toxicity

and wont harm germinating plants.

Ceramics Processing

Tape casting. Use of METHOCELproducts provides better flow andleveling and more uniformthickness. Low sodium residuesprovide the purity necessary forelectronic items. Thermal gelationreduces binder migration andsurface faults.

Extrusion forming. Used as atemporary binder and processingaid, METHOCEL cellulose ethersallow precise control of rheology inceramic mixes, permitting broaderoperating ranges. Lubricity reducesenergy consumption and die wear,and promotes smoother surfaces.Thermal gelation permits extrusionof extremely delicate, thin-walledshapes without sag or deformation.

Dry and isostatic pressing.

METHOCEL products provideoptimum grain lubrication fortighter, more uniform packing.The results are more predictable

green densities, less shrinkage duringfiring, and higher fired strengths.

Glazes/porcelain enamel.

METHOCEL cellulose ethersimprove control of viscosity andrheology and fire out completely inthe kiln.

Injection molding. Use ofMETHOCEL cellulose ethersprovides higher green densitiesand better green strength. In high-

temperature coatings/refractorymixes and mortars, METHOCELimproves workability andapplication properties. BecauseMETHOCEL products have lowionic salt residues, they wont lowermelting points. In fact, they canpermit a reduction in use ofplasticizers with low melting points.

Chemical Specialties

Resins. METHOCEL celluloseethers are used to control rheologyand as a colloidal stabilizer in avariety of epoxy, fiberglass, andurea-formaldehyde resins.METHOCEL provides ideal flowand leveling characteristics, plusquick-set properties due tothermal gelation.

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Applications for METHOCEL Cellulose Ethers


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Rubber. METHOCEL productsare used as mold-release agents,stabilizers, and thickeners in rubberlatexes. METHOCEL celluloseethers contribute to more uniform

drying and less pinholing.

PVC suspension polymerization.

METHOCEL products are used inPVC polymerization as primary andsecondary suspension agents. Theyprovide excellent particle size control,good porosity for improved plasticizerabsorption, low reactor scaling, andhigh bulk densities.

Construction Products

Drywall tape-joint compounds.

METHOCEL products impartworkability, shrink and crackresistance, slip, and adhesion intape-joint compounds. Waterretention properties increase opentimes and help maintain a wet edge.

Cement-based tile mortars.

METHOCEL cellulose ethers providewater retention and workabilityto Portland cement-based ceramictile mortars and grouts. They alsoimprove adhesion, reduce skinning,

and increase open time.

Masonry mortars. Used asperformance additives in masonrymortars, METHOCEL productsextend board life and improveworkability. METHOCEL alsocontributes to air entrainment, oftenreducing the need for other additivesfor this purpose.

Gypsum adhesives and gypsum andcement hand and spray plasters.

METHOCEL cellulose ethers

impart workability, pumpability,and consistency to adhesives andhand and spray plasters. They alsoprovide water retention and anti-sag properties.

Wall and ceiling textures.

METHOCEL products impartpumpability, adhesion, workability,and water retention in wall andceiling texturizing products.

Cement plaster and stucco.

METHOCEL cellulose ethersprovide water retention for propercuring, improved workability, andpumpability.

Foods

Bakery products. Thermal gelationaids in gas retention during baking,increasing baked volumes andimproving texture. METHOCELalso provides a more moist texture,increased shelf life, improvedemulsification of batters, and betterfreeze/thaw stability.

Confections. In glazes, icings, andcoatings, METHOCEL food gums

add lubricity for easier application,provide creamier texture, improvedspreadability, and clean flavorrelease. In addition, METHOCELgums thermally gel during heating,keeping icings and glazes intact, andduring cooling revert to the originalconsistency of the product.

Pie and pastry fillings. Thermalgelation reduces boil-over duringbaking and inhibits moisturemigration from fillings to crusts

during freezing. METHOCEL alsoimproves freeze/thaw stability.

Frozen desserts. METHOCELproducts modify ice-crystal size togive smoother textures and improveemulsion stability. Increased airentrainment improves overrun.

Whipped toppings. METHOCELproducts improve whippingproperties for better body andappearance. Improved emulsionstability prevents syneresis and

extends open times. METHOCELinhibits phase separation in frozentoppings, even through repeatedfreeze/thaw cycles.

Structured vegetable products.

METHOCEL products offerexcellent film formation and highbinding performance for foods thatneed to keep their components

together. Products like vegetarianburgers, onion rings, and formedpotato products are all improvedby the binding strength andfilm formation qualities ofMETHOCEL products.

Structured and extruded foods. Lowconcentrations of METHOCELgive optimum binding strength inmatrix systems. Due to moistureretention and oil insolubilityproperties, fried foods are more

moist, less greasy. Thermal gelationgives increased control over textureand bite. Increased lubricity aidsin processing.

Frying batters. In addition toforming an oil-insoluble barrier toblock oil absorption and moistureloss during frying, METHOCELproducts improve adhesion ofbatters to meat and vegetablesubstrates. As a result, blow-off ofbatters is reduced and the life of

frying oil is extended.Salad dressings and sauces. Betterstability for oil-in-water emulsionsextends the shelf life of productscontaining METHOCEL. Solids stayin suspension longer and body andpouring characteristics are controlled.

Gelled Fuels

Fuel thickeners. METHOCELcellulose ethers are used as thickenersfor gelled alcohol used in charcoal

lighters, restaurant candles, andcanned-fuel products.

Household Products

Cleaners and detergents. Useof METHOCEL provides viscositycontrol, cling, foaming, soilanti-redeposition, and emulsionstabilization to householdcleaners and detergents.

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Paints

Latex paints. METHOCELcellulose ethers are used asthickeners, protective colloids, andpigment-suspension aids in latex

paints. They provide high enzymeresistance which helps stabilizeviscosity. Film-forming propertiescontribute to better paint filmquality with fewer pinholes. Theproduct uniformity offered byMETHOCEL cellulose ethers canmean lower quality control costsand more predictable performancefor paints. Their use also improveswet-edge retention. They offerflexibility and ease of incorporation.

Paint Removers

Scrape-off and flush-off paintremovers. The unique combinationof organic and water solubilityoffered by METHOCEL productsmakes them ideal thickeners forscrape-off and flush-off paintremovers (both methylene chlorideand alternative paint strippers).They provide the thickening andcling needed to retain the paintremover on vertical or inclined

surfaces, yet permit the softenedpaint to be rinsed off easilywith water.

Paper Products

Grease-proof coatings, adhesives,

release coatings, and surfacesizings. Grease and oil barrierproperties, in conjunction withfilm-forming capabilities, makeMETHOCEL valuable in a varietyof paper coatings and sizings. The

excellent film properties (high tensilestrength and good elongation)offered by METHOCEL play keyroles in these applications.

Personal Care Products

Shampoos. METHOCEL celluloseether is widely used as a thickenerin shampoos. Because the thickeningperformance of METHOCELdoesnt depend on a high surfactant

level, its the thickener of choicefor shampoos designed for dry andnormal hair. METHOCEL alsohelps stabilize foams, so shampooshave better lather characteristics.

Body Gels. The natural lubricity ofMETHOCEL products can improveproduct flow, aid in dispensing andenhance sensory characteristics. Justas in shampoos, METHOCELcellulose ethers add texture andprovide a superior volume oflubricious, stable lather especiallyimportant in the formation ofbubble baths and shower gels.

Creams and lotions. METHOCELcan contribute film-forming andsecondary-thickening propertieswhich improve after-feel and othersensory characteristics in creamsand lotions.

Pharmaceuticals

Tablet coatings. METHOCELcellulose ethers form strong filmswith good adhesion. They providetaste-masking films and act asexcellent barriers for water-sensitivedrugs or components. Coatings

of METHOCEL also increasecompressive strength andreduce friability.

Granulation. Used at lowconcentrations as binders in thegranulation process, METHOCELproducts produce hard tabletswith low friability, yet dontnegatively affect tablet disintegration.METHOCEL allows the reductionof compression force, an importantfactor in extending the life of

tooling and equipment.Controlled release. METHOCELcellulose ether can be used forcontrolled-release pharmaceuticalsusing two different methods. It isused in hydrophilic-matrix tablets orcapsules as described in a separatebulletin on sustained release. Inaddition, METHOCEL is used indiffusion control films comprised ofMETHOCEL cellulose ethers and

ETHOCEL* ethylcellulose resins.The water-soluble METHOCELdissolves out of the film, leavingthe water-insoluble ETHOCELethylcellulose. Drug diffusion and

film porosity are controlled by theamount of METHOCEL used.

Water-soluble thermoplastics.

METHOCEL cellulose ethers canbe heated and mixed with aplasticizer for extrusion or moldinginto a wide range of physical forms.This process is used to producesingle-unit matrix tablets; multi-particle delivery, such as extrudedbeads or chips; transdermal patches;suppositories; or liquid-filled

hard-shell capsules.Liquid preparations. METHOCELproducts are used in oral andtopical liquid pharmaceuticalsbecause they are excellent thickeners,improve emulsion stability, suspendsolids, lubricate, and retain moisture.The protective colloid actionand emulsifying properties ofMETHOCEL also benefit manyliquid formulations.

PrintingPrinting inks. METHOCELcellulose ethers are used asthickeners and suspending agentsfor water-based inks.

Textiles

Textile printing pastes. Used asemulsion stabilizers in textileprinting pastes, METHOCELcellulose ethers help keep inks fromwicking into fabrics.

Fabric sizings. METHOCELhelps hold fibers together, whichstrengthens fabrics duringmanufacturing processes. Thelubricity of METHOCEL helps cutfriction, permitting fasterequipment speeds.

Temporary adhesives. Excellentwet-tack and quick-set propertiesmake METHOCEL an idealtemporary fabric adhesive.

9* Trademark of The Dow Chemical Company


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Chemical Inventory

METHOCEL products,methylcellulose and hydroxypropylmethylcellulose, comply with allapplicable rules and orders underToxic Substances Control ActPL94-469. The Chemical AbstractsServices Registry No. (CAS) is9004-67-5 for methylcellulose and9904-65-3 for hydroxypropylmethylcellulose.

METHOCEL products havealso been reported for the

following inventories:

European Inventory of ExistingChemical Substances (EINECS)

Australia Inventory of ChemicalSubstances (AICS)

Ministry of International Trade andIndustry Inventory (MITI, the

Japanese inventory)

Canadian Domestics SubstancesList (DSL)

Many countries are in the midst ofcreating new chemical inventories.

Pharmaceuticals

Premium grades of METHOCEL A,METHOCEL E, METHOCEL F,and METHOCEL K products areused for pharmaceutical and topicalapplications. Premium grades ofMETHOCEL products meet thespecifications of the United StatesPharmacopoeia (USP XXIII),

European Pharmacopoeia (EP) andJapanese Pharmacopoeia (JP) andare listed as methylcellulose andhypromellose1. In addition,methylcellulose (METHOCEL Aproducts) is Generally RecognizedAs Safe (GRAS) by the U.S. Foodand Drug Administration.

To support new drug applications in

the United States, masters files forthese products are on file at theBureau of Drugs of the U.S. Foodand Drug Administration.

Foods

METHOCEL food gums havelong been used in the food industry.METHOCEL food gums areapproved within the FoodChemicals Codex and are listed asmethylcellulose and hydroxypropyl

methylcellulose.

In the U.S., methylcellulose isapproved as a multiple purposeGRAS food substance according to21CFR 182.1480. It is also allowedfor use in meat products accordingto 9CFR 318.7 and 9CFR 381.147.Hydroxypropyl methylcellulose isapproved for direct food use by theFDA under 21CFR 172.874. It isalso approved by the USDA as anemulsifying agent, binder, thickener,

and stabilizer and is listed in theStandards and Labeling Policy Bookpublished by the USDA. Becausethey are approved for direct fooduse, METHOCEL products can alsobe used as packaging componentsand in indirect food applications.

In the European Union,METHOCEL food gums areapproved for use within theEuropean Directive 95/2/EC.Hydroxypropyl methylcellulose and

methylcellulose are included inAnnex I of this Directive.

When labeling these foodingredients, one can use either theirproper chemical names or theircommon names. Therefore, onecould use methylcellulose ormodified vegetable gum forMETHOCEL A products. For

METHOCEL E, F, or K products,

one could use hydroxypropylmethylcellulose or carbohydrategum. METHOCEL products arealso certified as kosher for year-round and Passover use by theUnion of Orthodox JewishCongregations of America.

Pesticide Use

Under 40CFR 180.1001, certaininert ingredients used in pesticideformulations are exempt from therequirements of a tolerance.Methylcellulose and hydroxypropylmethylcellulose may be used informulations applied to growingcrops or raw agriculturalcommodities after harvest. BothStandard and Premium gradeMETHOCEL cellulose etherproducts are appropriate.

10

Regulated Uses

1 The former official monograph name of hypromellose

was hydroxypropyl methylcellulose or HPMC.


13/32

METHOCEL cellulose ether

products are carbohydratepolymers which dissolve in coldwater (and in some instances incertain organic solvents) byswelling and subsequent hydration.There is no sharp solubility limitsuch as occurs in the dissolution ofionizing salts. The concentration ofMETHOCEL in solution is usuallylimited by the viscosity that amanufacturer is equipped to handle.It also depends on the viscosityand chemical type of METHOCELproduct used. Solutions of low-viscosity products can be made at10% to 15% concentration. High-viscosity products find a normallimit at 2% to 3% concentration.

The form of METHOCELcellulose ether product chosen(powder or surface-treated powder,or granules) influences the techniquesused to make solutions. Surface-treated and granular products canbe added directly to aqueoussystems. They disperse readily with

mild agitation and dissolve (buildviscosity) gradually under neutralconditions. The dissolution rateof surface-treated products canbe increased by adjusting to analkaline pH after dispersing thepowder in water. Althoughuntreated METHOCEL powdersare soluble in cold water, theymust first be thoroughly dispersedin the water to prevent lumping.

Working with Surface-treated

Dispersible PowdersIn many applications, thecombination of easy dispersion incold water and rapid hydration(viscosity build) is desirable.Surface-treated METHOCELpowders are chemically treated sothat they become temporarilyinsoluble in cold water. This allows

the METHOCEL product to be

added to a formulation anddispersed at relatively low shearwithout any significant viscosityincrease initially.

The time delay of the hydrationor viscosity build is a function ofthe level of surface treatment aswell as temperature, pH of thesystem, and concentration of theMETHOCEL product. Normally,the concentration of METHOCELin the system does not become afactor until the concentration

exceeds 5% by weight (relativeto water in the system). At higherconcentrations, the time ofhydration (referred to as delaytime) is reduced. The delay time isgenerally reduced as temperatureis raised. Figure 2 shows a typicaldelay time as a function of pH,evaluated at room temperature.

In many cases it is desirable totrigger viscosity build immediatelyfollowing dispersion. Aqueousslurries can be held for 45 minutes

and still remain usable in neutral

systems. A trigger can conveniently

be used by adding a small amountof a base, such as ammoniumhydroxide, sodium bicarbonate,etc. If METHOCEL is dispersed inneutral water (pH approximately 7),there is adequate time for thoroughdispersion. Addition of base toraise the pH to approximately 9causes the hydration to becompleted in just a few minutes.

For best results and to achievemaximum hydration, surface-treatedpowders should be added with

good agitation to a neutral pHsystem. The system should beagitated thoroughly for a fewminutes, followed by an adjustmentof pH to 8.5 to 9.0 with continuedagitation, until full viscosity isreached (usually 10 to 30 minutes).Once the pH has been shifted tothe alkaline side (pH 8.5 to 9.0),allowing full and rapidsolubilization of the surface-treatedproduct, solutions are stable overthe pH range of 3 to 11.

11

How To Prepare Aqueous Solutions ofMETHOCEL Cellulose Ethers

Figure 2: Typical Hydration Delay Time of Surface-treated METHOCELProducts as a Function of pH

0 2 4 6 8 10pH

1000.0

100.0

10.0

1.0

0.1

HydrationTime,min


14/32

The addition of a slurry to analkaline pigment grind or fillerdispersion, or the addition of aslurry to a basic pigment-latexformulation, provides rapid

solubilization and uniform viscositydevelopment. The addition of dry,alkaline pigments or fillers to aslurry on high-speed or low-speedmixing equipment also results inrapid solubilization and viscositydevelopment.

CAUTION: Attempts to adjust the pH of

high-concentration slurries may lead to

excessively high viscosity so that they cannot

be pumped or poured. The pH adjustment

should be made only after a slurry is diluted to

the concentration at which it will be used.

Dispersion Technique

1. Add the surface-treated METHOCELpowder to the water.Begin agitation.

2. Continue agitationand add sufficientammonium hydroxide,sodium bicarbonate,or other alkaline

material (e.g., pigmentgrind) to the dispersionto obtain a pH of 8.5 to 9.0.This will result in rapid viscositydevelopment. Continue agitationuntil sufficient hydration hasbeen achieved.

Working with Untreated Powders

Although METHOCEL powdersare soluble in cold water, they mustfirst be thoroughly dispersed in the

water to prevent lumping. In someapplications, dispersion can beaccomplished at ambienttemperatures or in cold water byusing an eductor funnel or high-shear mixer. However, if untreatedpowders are added directly to coldwater without sufficient agitation, alumpy solution may result. Lumpingresults from incomplete wetting ofthe individual powder particles.Only part of the powder dissolves,a gelatinous membrane which

shields the remaining powder fromcomplete hydration. Severaldispersion techniques are commonlyused and are described below. Eachhas advantages in certainapplications.

Dispersion in Hot Water

Often called the hot/cold technique,this method takes advantage of theinsolubility of METHOCEL cellulose

ethers in hot water. The powder isfirst dispersed by mixing thoroughlywith 1/5 to 1/3 of the total requiredvolume of water that has beenheated to above 90C (194F).Mixing continues until all particlesare thoroughly wetted.

For complete solubilization, theremainder of the water is thenadded as cold water or ice to lowerthe temperature of the dispersion.Once the dispersion reaches thetemperature at which that particularMETHOCEL product becomeswater soluble, the powder begins tohydrate and viscosity increases.

12

Figure 3: Viscosity Development of METHOCELA andMETHOCEL K Products Slurried at 2% in Hot Water

100 80 60 40 20 0Temperature, C

10,000

1,000

100

10

Viscosity,mPa.s

Viscosity on InitialCooling ofMETHOCEL A Premium

Viscosity on InitialCooling ofMETHOCEL K Premium


15/32

In some applications, it may bedesirable to heat the entire volumeof water, disperse the METHOCELpowder, then cool the mixture whileagitating until hydration is complete.

It is very important, however, tohave adequate cooling after wettingwith hot water to ensure completehydration and viscosity development.

For improved clarity and reproduciblecontrol of viscosity, solutions ofMETHOCEL A cellulose etherproducts (methylcellulose) should becooled to 0 to 5C (32 to 41F)for 20 to 40 minutes. In general,solutions of METHOCEL E,METHOCEL F, METHOCEL J,

and METHOCEL K brandcellulose ethers (hydroxypropylmethylcellulose) require cooling to20 to 25C (68 to 77F) or below.

Because complete hydration dependson adequate cooling, METHOCELE, F, J, and K brand products arefrequently used in applicationswhere cold water is not available.Figure 3 illustrates the effects ofcooling hot slurries of METHOCELA and METHOCEL K products.

This figure shows that a slurry ofMETHOCEL K brand celluloseether requires much less coolingfor hydration than a slurry ofMETHOCEL A cellulose ether.Slurries of METHOCEL E, F, and Jbrand products also require lesscooling than METHOCEL Abrand products.


1. Heat approximately1/3 the requiredvolume of water to atleast 194F (90C).

2. Add the METHOCELpowder to the heatedwater with agitation.

3. Agitate the mixtureuntil the particles arethoroughly wettedand evenly dispersed.

4. For completesolubilization, addthe remainder of thewater as cold wateror ice to lower the

temperature of the dispersion.Once the dispersion reaches thetemperature at which that particularMETHOCEL product becomeswater soluble, the powder begins tohydrate and viscosity increases.See pages 12 and 13 for coolingtimes and temperatures for specific

METHOCEL products.

5. Continue agitationfor at least 30 minutesafter the propertemperature isreached. Yoursolution ofMETHOCEL celluloseether is now ready to use.

Dispersion by Dry-Blending

Dry-blending involves mixingMETHOCEL powder with otherdry ingredients before adding thewater component. Dry-blendingseparates the particles of METHOCELcellulose ethers to allow thoroughwet-out and complete hydrationwhen water is added. The minimumratio of other dry, powderedingredients to METHOCEL powdervaries from 7:1 to 3:1.


1. CombineMETHOCEL powderwith other dry-powder

ingredients. Thesuggested ratio of otherdry-powder ingredients

to METHOCEL is 7:1; however, theratio may vary from 7:1 to 3:1.

2. Thoroughly blendthe dry components.

3. Add the dry mixto the water with

agitation. The rate ofhydration will dependupon both the relative

particle sizes and the rate ofagitation during and after additionof the mixture to the water.

4. Agitate until theMETHOCEL powderhas completelyhydrated and thesolution is consistentlysmooth. Your solution

of METHOCELcellulose ether is now ready forfurther processing.

Dispersion in Concentrated SaltSolutions

Both untreated and surface-treatedMETHOCEL cellulose ethers canbe dispersed in concentrated saltsolutions. Dissolution occurs whenthe brine is diluted with cold water.

13


16/32

Solubility in Nonaqueous

SolventsThe solubility of METHOCELcellulose ethers in nonaqueous mediavaries according to the nature andquantity of substituent groups on theanhydroglucose chain. When using awater-miscible, organic solvent, suchas an alcohol or glycol, use a ratioof at least 5 to 8 parts of solvent to1 part METHOCEL.

Dispersion in Non-solvent Media

Untreated METHOCEL celluloseethers may also be dispersed innon-solvent media such as vegetableoil, propylene glycol, polyethyleneglycol, glycerine, corn syrup, andhigh-fructose corn syrup. A ratio of5 to 8 parts non-solvent to 1 partMETHOCEL is recommended toobtain a fluid slurry. The dispersionof METHOCEL in a non-solventmedium may then be added to coldwater, or the cold water may beadded to the dispersion.


1. Add the METHOCELcellulose ether to thenon-solvent. A ratio of58 parts non-solvent to1 part METHOCEL isrecommended to obtaina liquid slurry.

2. Agitate the mixtureand METHOCELpowder until the particlesof METHOCEL celluloseether are evenly dispersed.

3. The dispersion ofMETHOCEL in a non-solvent medium may beadded to cold water, orthe cold water may beadded to the dispersion.

4. Continue mixing untilthe METHOCEL powderis completely hydratedand the solution issmooth. You can now addthe remaining ingredientsin your formulation.

14

How To Prepare Solutions of METHOCEL CelluloseEthers in Nonaqueous Solvents and Nonsolvent Media


17/32

METHOCEL cellulose ether

products are white to slightly off-white powders which are essentiallyodorless and tasteless. The apparentdensity of the powders ranges from0.25 to 0.70 g/cm3 (250700 kg/m3).

Moisture Sorption

METHOCEL products sealed intheir original shipping containersabsorb little to no atmosphericmoisture. Once a container isopened, however, there is pickup

of moisture from the air. Whenexposed METHOCEL celluloseether is weighed, a portion of thetotal weight, therefore, may bewater. Such weight must be correctedfor moisture content to ensure thatthe proper weight of METHOCELis used to give the desired viscosity.

To minimize moisture pickup,opened bags should be tightlyresealed. The moisture-sorptionrate of METHOCEL K brandproducts is somewhat greater thanfor METHOCEL A brand products.However, the moisture-sorptionrates are about the same within asingle chemical type. Typicalmoisture sorption is shown inFigure 4.

Resistance to Microorganisms

An important property ofMETHOCEL cellulose etherproducts is their high resistanceto attack by microorganisms.METHOCEL products with higherdegrees of substitution are especiallyresistant to enzymes. The fact thatvirtually all METHOCELmethylcellulose and METHOCELhydroxypropyl methylcelluloseethers pass through the intestinaltract essentially unchanged attests to

the stability of these products to awide range of biochemical andenzymatic systems. Shelf-life inpaints and other latex-basedcoatings, and stability ofsolutions and other productscontaining METHOCEL celluloseether, can be greatly increased bythis resistance to microorganisms.

As the cellulose is modified by

substitution with various radicals,such as alkyl and hydroxyalkylgroups, resistance to microbialattack increases. Several researchershave reported that the degree ofsubstitution (D.S.) of water-solublecellulose derivatives was a primaryfactor, with a threshold D.S. valueof 1.0 required for protection.

Because METHOCEL celluloseether products have excellentuniformity of substitution, with a

D.S. much higher than 1.0, theypossess excellent resistance tomicrobial attack.

15

Properties of METHOCEL Cellulose Ethers inPowder Form

Figure 4: Equilibrium Moisture Contentvs. Percent Relative Humidity, 25C

0 10 20 30 40 50 60 70 80 90 100

% Relative Humidity, Mean Average Value,+95% Probability

80

70

60

50

40

30

20

10

0

%H2

O,

25C

H.S. Levinson and E.T. Reese, J. Gen. Physiol. 33, No. 601 (1950).E.T. Reese, R.G.H. Siu, and H.G. Levinson, J. Bacteriology59, No. 485 (1950).E.T. Reese, Ind. Eng. Chem. 49, No. 104 (1957).


18/32

Some of the general solution

properties of METHOCEL celluloseether products are listed in Table 6.

Rheology of Solutions ofMETHOCEL Cellulose Ether

The rheology of solutions ofMETHOCEL plays an importantrole in many practical applicationswhere the modification of flowbehavior is essential (for example,paints, cosmetics, food products,building products). A Newtonian

fluid is one whose viscosity isindependent of shear rate (orvelocity gradient of flow). In actualpractice many systems exhibit non-Newtonian flow behavior whereapparent viscosity may decrease(pseudoplastic) or increase (dilatant)with increasing rate of shear.

Rheology of an aqueous solution

of METHOCEL is affected by itsmolecular weight, concentration,temperature, and by the presence ofother solutes. In general, aqueoussolutions of METHOCEL exhibitpseudoplastic flow behavior.Pseudoplasticity increases withincreasing molecular weight orconcentration. However, at verylow shear rates, all solutions ofMETHOCEL cellulose ether appearto be Newtonian and the shear ratebelow which the solution becomes

Newtonian increases with decreasingmolecular weight or concentration.Figures 5 and 6 illustrate thisbehavior (the numbers on curvesindicate viscosity types).

16

Properties of Solutions of METHOCEL Cellulose Ethers

Table 6: General Solution Properties

Specific gravity, 4C, all types

1% solutions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.0012

5% solutions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.011710% solutions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.0245

Refractive index, 2% solutions, all types

1.336

Partial specific volume

4,000 mPas METHOCEL A . . . . . . . . . . . . . . . . . . . . . . . 0.725 cm3/g (0.087 gal/lb)

4,000 mPas METHOCEL E . . . . . . . . . . . . . . . . . . . . . . . 0.767 cm3/g (0.092 gal/lb)

4,000 mPas METHOCEL F . . . . . . . . . . . . . . . . . . . . . . . 0.734 cm3/g (0.087 gal/lb)

5,000 mPas METHOCEL J . . . . . . . . . . . . . . . . . . . . . . . 0.725 cm3/g (0.087 gal/lb)

4,000 mPas METHOCEL K . . . . . . . . . . . . . . . . . . . . . . . 0.717 cm3/g (0.086 gal/lb)

15,000 mPas METHOCEL K . . . . . . . . . . . . . . . . . . . . . . 0.724 cm3/g (0.087 gal/lb)

Freezing point, 2% solutions, all types

0.0C at 2% concentration

Surface tension, 25C, 0.05% concentration

Water . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7274 x 10-3 Newton/meter (7274 dynes/cm)

Methylcellulose. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5359 x 10 -3 Newton/meter (5359 dynes/cm)

Hydroxypropyl methylcellulose . . . . . . . . . . . . . . . . . . . 4355 x 10-3 Newton/meter (4355 dynes/cm)


19/32

17

Figure 5: Apparent Viscosity vs. Shear Rate, 2% Aqueous Solutions, 20C

0.1 1 10 100 1,000

Shear Rate, s-1

10,000

1,000

100

10

ApparentViscosity,mPa.s

4,000

1,500

400

100

25

Figure 6: Apparent Viscosity vs. Shear Rate, for Aqueous Solutions of 4,000mPa.s METHOCEL Cellulose Ethers at Various Concentrations

0.1 1 10 100 1,000

Shear Rate, s-1

10,000

1,000

100

10

ApparentViscosity,mPa.s@2

0C

2%

1.5%

1%

0.5%


20/32

Molecular Weight/ViscosityRelationships

The apparent viscosity of anaqueous solution of a METHOCELcellulose ether is proportional to themolecular weight or chain length of

the specific METHOCEL productused. Commercial designations ofMETHOCEL products are basedon viscosity values determined inwater at 20C, with a concentrationof 2% METHOCEL. Themeasurement methods used aredescribed in the current ASTMmonographs D1347 and D2363.The correlation between the numberaverage molecular weight (Mn) andthe commercial viscosity designationfor METHOCEL A cellulose ethers

is shown in Figure 7.Table 7 provides further informationregarding the correlation of numberaverage molecular weight with thecommercial viscosity designation.Intrinsic viscosity is the limitingquotient of the specific viscositydivided by the concentration asinfinite dilution is approached (asthe concentration approaches zero).The number average molecularweight (Mn) is calculated from the

limiting osmotic pressure of thesolvent as the concentration ofthe solute approaches zero. Theaverage molecular weight (Mw)will be 3 to 10 times the Mn.

Effect of Concentration onViscosity

Most formulations require apredetermined product viscosity ofMETHOCEL cellulose ether. Figure8 shows how the concentration of

METHOCEL products of varyingviscosity affects the aqueous solutionviscosity at 20C. The measurementswere made using an Ubbelohdeviscometer (ASTM D2363). Datafor both low and high molecularweight METHOCEL products areshown and represent the averagematerial found within a viscosityspecification.

18

Molecular Weight

Figure 7: Molecular Weight/Viscosity Correlation, 20C

1,000 10,000 100,000

100,000

10,000

1,000

100

10

0

ViscosityofanAqueo

usSolution,mPa.s@2

0C

Mw

Mn

Table 7: Viscosity of Methylcellulose of Various Molecular Weights

5 1.2 53 10,00010 1.4 70 13,00040 2.0 110 20,000

100 2.6 140 26,000400 3.9 220 41,000

1,500 5.7 340 63,0004,000 7.5 460 86,0008,000 9.3 580 110,000

15,000 11.0 650 120,00019,000 12.0 750 140,00040,000 15.0 950 180,00075,000 18.4 1,160 220,000

Intrinsic Number Average Number AverageViscosity Grade Viscosity Degree of Molecular2%, 20C, mPas (h), dL/g Polymerization Weight (Mn)


21/32

This graph is plotted on an 8throot scale, not a logarithmic scale.The 8th root of the viscosity isa roughly linear function ofthe concentration.

The equation which expressesthe illustrated approximaterelationship between solutionviscosity and polymerconcentration is 1/8 = (C) + 1,where is the solution viscosityin millipascal-seconds, C is thepolymer concentration in solution(expressed in percent), and is aconstant specific to the molecularweight. The value of may becalculated by substitution and may

then be used to calculate theapproximate viscosity at thedesired concentration.

For example, for a 4,000 mPasproduct, (4,000)1/8 = (C) + 1.Solving for yields a value of0.910. For a 1,500 mPas product,(1,500)1/8 = (C) + 1. Solving for yields a value of 0.747. Havingcalculated for a particularMETHOCEL product, this valuecan be used to calculate viscosity

at other concentrations.To find the line for any intermediategrade, locate the desired 2%viscosity above 2% on the abscissaand draw a straight line to thepoint of origin.

Blending for IntermediateViscosity

METHOCEL products of the samesubstitution type, but of different

viscosity grades, can be blended toobtain an intermediate viscositygrade. Figure 9 is a blending chartthat can be used for this purpose.

To use the chart, mark theviscosity of one material along theleft axis (Scale A) and the viscosityof the other material along theright axis (Scale B). Connect thetwo points in a straight line thatcrosses the graph. In the exampleshown, the viscosities of the

starting materials are 400 mPason the left and 15,000 mPas onthe right.

Now find the desired final

viscosity on either axis and draw ahorizontal line that intersects withthe first line. From this intersectionpoint, draw a vertical line down tothe bottom scale. The number ofthat scale shows the percentage ofScale B Material needed in theblend. In this example 4,000 mPasis the desired final viscosity. So therequired blend is 60% of the15,000 mPas (Scale B) materialand 40% of the 400 mPas(Scale A) material.

19

Figure 8: Viscosity/Concentration Relationships

0 1 2 3 4 5 6 7

% METHOCEL Cellulose Ether

100,000

75,000

50,000

Viscosity,mPa.s

@2

0C

15,000

10,000

4,000

1,500

1,000

400

250

100

50

2515

10

1

15

5

50

100

400

4,000

15,000

40,000

100,000

1,500


22/32

The relationship may be expressedmathematically as: B

1/8 = x111/8 +

x221/8 , where x1 and x2 are the

weight fractions of componentsone and two, respectively.

The example on the chart showsthat 60% of 15,000 mPas materialand 40% of the 400 mPas materialare needed to make a blend havinga viscosity of 4,000 mPas.

Effect of pH on Viscosity

Because METHOCEL productsare nonionic, the viscosities oftheir solutions are generally stableover a wider pH range than arethe viscosities of gums that are

ionic in nature. Outside the rangeof pH 3 to 11, however, there maybe a gradual loss of viscosity athigher temperatures or after longperiods of standing, especially withhigh-viscosity solutions. Solutionsof METHOCEL cellulose ethers inacids or in strong caustic solutionswill decrease in viscosity. Thisfactor should be consideredwhen determining the shelf lifeof products.

Effect of Additives on Viscosity

In the preparation of formulations,viscosities may occasionally resultwhich are considerably higher thanexpected. This phenomenon canbe caused by the interaction ofMETHOCEL with one or moreof the formula ingredients. As aresult, it may be possible to useless thickener and still haveadequate viscosity.

This effect usually passes througha maximum that is dependent onthe concentration of the interactingmaterials and on the presence ofother ingredients such as pigments,latex particles, or preservatives.

In systems having lowerconcentrations of additives (~1%),METHOCEL A or METHOCEL Fproducts are frequently suitable. Insystems where the concentration ofadditives is rather high (~10%),the more highly substitutedproducts such as METHOCEL E,

J, or K products may be morecompatible.

Effect of Freezing on Solutions

Solutions of METHOCEL celluloseether products do not undergoseparation into phases uponfreezing. There is no separationof fluid layers (syneresis) orformation of insoluble

precipitates or haze. This lack ofphase separation on freezing isparticularly important in frozenfood items. As solutions ofMETHOCEL cellulose etherproducts are cooled, solubilizationincreases, as evidenced byincreasing viscosity and improvedclarity of solutions. When thesolutions freeze, part of the wateris held in the latent super-cooledstate and does not freeze. The heat

normally released on freezing (heatof fusion) is decreased by theamount of the super cooling.

20

Figure 9: Blending Chart

0 20 40 60 80 100

% of Scale B Material in Blend

100,000

ScaleA

Viscosity,mPa.s@2

0C

10,000

1,000

100

10

400

100,000

10,000

1,000

100

10

Sca

leB

Viscosity,mPa.s@2

0C4,000

15,000


23/32


24/32

METHOCEL cellulose etherspossess unique solubility propertiesin aqueous media. These productsare insoluble in water that hasbeen heated above a particulartemperature. Below thosetemperatures, the solution andsolubility of the METHOCELcellulose ether products increase asthe temperature is lowered. Aqueoussolutions of METHOCEL celluloseethers will gel when heated totemperatures that are specific foreach type. The gels are completelyreversible and the solutions liquefyupon cooling. This unique bulk

thermal-gelation property provesvaluable, compared to that of othernatural and synthetic gums, in awide variety of applications.

Bulk thermal gelation of aqueoussolutions of METHOCEL is thoughtto be primarily caused by thehydrophobic interaction betweenmolecules containing methoxylgroups. In a solution state at lowertemperatures, molecules are hydratedand there is little polymer-to-polymer

interaction other than simpleentanglement. Figure 10 shows theviscosity of a typical solution as it isheated to its gel temperature, thencooled to the original temperature.

As the temperature of the solutionis increased, the cellulosic polymersgradually lose their water ofhydration, and viscosity decreases.When the gel point is reached,sufficient dehydration of thepolymer occurs to cause apolymer-to-polymer association,and the solution begins to gel.

Gel strength continues to build asthe temperature is held above thegel point.

When the solution is cooled, the geleffect begins to reverse and viscositydrops rapidly. Finally, the viscosityof the cooling solution mergeswith the original heating curveand increases as the temperaturedecreases. Once the solution hascooled, the viscosity is the same as itwas originally. Thus, the thermalgelation process is reversible andcan be repeated if desired.

22

Thermal Gelation in Aqueous Media

0 10 20 30 40 50 60 7Temperature, C

Vis

cosity,mPa.s

200

160

120

80

40

0

Gelled

Incipient GelationTemperature

Con

tinue

dH

ea

ting

Heating

Cooling

Figure 10: Gelation of 2.0% Aqueous Solutionof METHOCEL A100 Methylcellulose, Heating

Rate 0.25C/min


25/32

Controlling Gel Temperature

The specific temperature at whichbulk thermal gelation occurs (theincipient gelation temperature orIGT) and the firmness of the gel aregoverned by the nature and quantity

of the substituent groups attached tothe anhydroglucose ring and, thus,vary with each type of celluloseether. The molecular weight of theparticular METHOCEL productselected has little effect on the geltemperature. However, increasingthe concentration of the solutionlowers the gel temperature as shownin Figure 11.

Within the range of viscosityavailable in the A type, the low-viscosity products will have gel

points substantially higher thanthose of the high-viscosityproducts. The spread between highand low viscosity for the otherMETHOCEL cellulose ether typesis relatively narrow.

The Effects of Heating Rate andAgitation on Gelation

Accurate measurement of gelationtemperature requires care becauseit is a function of the rate of heating

and the rate of shear. Both a highrate of shear and a fast heatingrate result in an apparently highgel temperature.

Agitation also affects the strength ofthe gel. Continued rapid agitationduring gelation may break downthe gel structure and alter both thetexture and strength of the gel. Formaximum development of gelstrength, heat the solution wellabove the gelation temperature

under quiescent conditions.

Gel Strength and Texture

The texture and strength of gelsproduced by heating solutions ofMETHOCEL cellulose ethers varieswith the product type, viscositygrade, and concentration of

METHOCEL used. In applicationswhere a strong, elastic gel is desiredat slight elevations in temperature,METHOCEL A products arerecommended. For softer, non-rubbery gels, METHOCEL F orE products should be used. For

an even softer gel texture,METHOCEL K or METHOCEL Jproducts are suggested.

In general, the strength of the gelincreases sharply as molecularweight increases and graduallybecomes constant at or above aviscosity of 400 mPas. Gelstrength also increases withincreasing concentration.

Effect of Concentration on Thermal

GelationAs the temperature of a solution ofMETHOCEL cellulose ether israised, hazing of the solution occursimmediately prior to gelation, andthe viscosity may start to rise. Atthis point, if the concentration ishigh enough, the solution willchange to a soft or firm gel. If theconcentration is below 0.5%, a fluidmixture of individual gel particlesand water is formed, rather than a

firm gel.In general, as the concentrationof METHOCEL cellulose ether isincreased, the gelation temperaturewill be lowered. An increase of 2%in concentration can cause a 10Cdrop in the gelation temperaturefor METHOCEL A cellulose etherproducts. A 2% increase inconcentration of a solution ofMETHOCEL F cellulose etherproduct lowers the gelationtemperature by only 4C.

Interfacial Gelation

In addition to bulk-phase gelation,METHOCEL cellulose ethers alsoexhibit interfacial or surface gelationphenomena as a result of theirsurfactant nature. Interfacial gelationplays an important role in many

applications where a protectivecolloid, emulsification, or surfactantfunction is desirable. Examplesinclude: suspension polymerization

of vinyl chloride; aqueous foamstabilization in shampoos, bubblebaths; and the stabilization ofnon-dairy whipped toppings andsalad dressings.

To achieve bulk thermal gelation,concentrations of 1.5 wt % aregenerally necessary. However, evenat concentrations as low as 0.001wt %, many METHOCEL productsexhibit surface thermal gelationdue to the migration of polymer

molecules to the air/water interface.Maximum gelation properties areachieved with METHOCEL A, E,and F.

The equilibrium concentration ofMETHOCEL products at any giveninterface depends upon the natureof the interface, presence of othersolvents, temperature, and potentialfor formation of associativestructures with other surfactants.However, the concentration ofMETHOCEL at an interface can beorders of magnitude greater thanthat presumed to be present in thebulk phase. As a result, surface filmformation (surface gelation) occurs.

23

Figure 11: Gelation Temperature asa Function of Concentration

1 2 3 4 5 6 7 8 9 10 11 12Concentration, Wt. %

60

55

50

45

40

35

30

25

Gelation

Temperature,

C METHOCEL ESlope = -1.0

METHOCEL FSlope = -1.77

METHOCEL ASlope = -2.33


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As a specific example, a 0.01 wt %solution of METHOCEL A15 LVcellulose ether exhibits surfacegelation at 20C, whereas bulkgelation with the same productwould require a concentrationexceeding 12 wt % at such a lowtemperature. A 0.01 wt % solutionof METHOCEL A15 LV cannot be

made to undergo bulk gelation atany temperature.

Surface gelation (filming) occursvery rapidly in many solutions ofMETHOCEL products whetherdilute or concentrated. This effectis most evident (and troublesome)when one employs du Nouytensiometry to determinesurface tension.

Generally speaking, increasing themolecular weight, concentration,or temperature of a solution ofMETHOCEL will promote theonset of surface gelation just asin bulk thermal gelation.

Effect of Additives on ThermalGelation

Additives may either increaseor decrease thermal-gelationtemperature, depending on whetherthe additive exhibits a coagulantor a solubilizing effect on theMETHOCEL product. For example,solutes such as ethanol, PEG 400,and propylene glycol all raise the gelpoints of METHOCEL products.

This is due to the solubilizing effectwhich they impart. Additives suchas glycerin, sorbitol, and salts lowergel points by lowering the solvency ofthe aqueous system, resulting in a

more rapid dehydration of theMETHOCEL product (Table 8).

If a manufacturer requires a highthermal gelation temperature andplans to use additives known toreduce the gel temperature, aMETHOCEL product with a gelpoint higher than the temperaturerequired should be used. As theconcentration of the gel-causingadditive increases, the thermal geltemperature decreases. Although the

behavior of a particular solute mustbe determined empirically, thefollowing general guidelines apply.

24

% METHOCEL METHOCEL METHOCEL METHOCELAdditive Additive A15C, C F4M, C K4M, C J5M, C

None 0 50 63 85 62

NaCl 5 33 41 59 42MgCl2 5 42 52 67 50

FeCl3 3 42 53 76 53

Na2SO4 5 salted out salted out salted out salted out

Al2(SO4)3 2,5 salted out 45 48 41

Na2CO3 5 salted out salted out salted out salted out

Na3PO4 2 32 42 52 43

Sucrosea

5 51 66 84 60

Sucrose 20 44 59 61 53

Sorbitol 20 30 46 48

Glycerine 20 34 60 65-70 55

Ethanola

20 >75 >75 >75 >78

Polyethylene

Glycol 400a

20 52 >80 >80 >78

Propyleneglycola

20 59 >80 >80 >78

aNote: This material raises the gelation temperature.

Table 8: Effect of Additives on Gelation Temperature for 2% Solutions of METHOCEL Cellulose Ether


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Additives Which Lower Gel Points

Most electrolytes, as well assucrose, glycerine, etc., lower thegel point because they have a

greater affinity for water anddehydrate the cellulosic polymer.Decreases in gel temperature area function of the ions present inthe additive.

Additives Which Raise Gel Points

The effect of an additive that raisesgel point varies with differentMETHOCEL products. Forexample, the amount of propyleneglycol required to increase thethermal gel point of a solution ofMETHOCEL A cellulose ether by4C will increase the gel point ofa solution of METHOCEL F by10C and METHOCEL Kby 20C.

The increase in the thermal gelpoint is directly proportional tothe increase in concentration ofthe additive. Figures 12 and 13illustrate the relationship betweenconcentrations of ethanol andpropylene glycol and the thermal

gel point of representativeMETHOCEL products.

25

Figure 13: Effect of Propylene Glycol on GelTemperature, 2% Solutions

0 5 10 15 20Propylene Glycol, % by Volume

25

20

15

10

5

0

ChangeinThermalGelTemp.,

C

METHOCEL A4M(4,000 mPa.s)

METHOCEL F4M(4,000 mPa.s)

Figure 12: Effect of Ethanol on GelTemperature, 2% Solutions

0 5 10 15 20Ethanol, % by Volume

25

20

15

10

5

0

ChangeinThermalGelTem

p.,

C

METHOCEL A4M(4,000 mPa.s)

METHOCEL F4M(4,000 mPa.s)


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High-strength, water-soluble films,supported or unsupported, maybe rolled, cast, or extruded fromformulations of METHOCELcellulose ether products. These

clear, smooth films or coatingsare impervious to oils, greases,and most solvents. They are alsoeffective binders, even when loadedwith inert materials.

Tensile and elongation propertiesof typical films of METHOCELcellulose ethers cast from water areshown in Table 9. The need for aplasticizer may be more pertinentwhen using low viscosity 5 mPasMETHOCEL cellulose ethers

because of lower film elongationproperties. This can be more acute ifdrying temperatures are too high.

Effect of Additives on FilmSolubility

The water solubility of films andcoatings of METHOCEL celluloseethers can be altered by the use of

cross-linking compounds and resins.The degree of insolubility can becontrolled by the choice and quantityof a cross-linking reagent. All ureaformaldehyde, melamineformaldehyde, and resorcinolformaldehyde resins can be used.Dialdehydes such as glyoxal are alsoeffective. Supplier literature shouldbe consulted for selection ofcatalysts and curing compounds.

Resistance of Films to Solvents

Films and coatings of METHOCELare unaffected by animal andvegetable oils, greases, and petroleumhydrocarbons. Of the differenttypes of products, METHOCEL A,METHOCEL F, and METHOCELK brand products are most resistant.

Thermoplastic Forming

Procedures for preparing a dry-mixformulation of METHOCEL E or

J cellulose ether products withpropylene glycol and otherplasticizers are available for extrudedsheeting and injection or compressionmolding. Such mixes may becompounded in a ribbon-typeblender at room temperature andsatisfactorily handled by a feederdesigned for powders. Most feedersperform better if the dry mix is firstdensified by being passed througha set of press rolls or through apellet mill.

Flakes of METHOCEL E or Jcellulose ether products withpropylene glycol and other

plasticizers may be extruded ormolded directly into a finished,water-soluble product attemperatures ranging from 80 to160C (176 to 320F). Properlyplasticized sheet and tubing ofMETHOCEL cellulose ether can beheat-sealed at about 130C (266F).

26

Table 9: Properties of Unplasticized Films of METHOCEL Cellulose Ethers

Propertiesa METHOCEL A15 LV METHOCEL E15 LV

Specific gravity 1.39 1.29Area factor 24,000 in2/lb/mil 25,860 in2/lb/mil

Moisture vaportransmission rate,100F (38C), 50% RH 67.5 g/100 in2/24 h/mil 65 g/100 in2/24 h/mil

Oxygen transmissionrate, 75F (24C) 25 cm3/100 in2/24 h/mil 70 cm3/100 in2/24 h/mil

Tensile strength,75F (24C), 50% RH 9,000 Ib/in2 (62 MPa)10% 10,000 Ib/in2(69 MPa)

10%Elongation,

75F (24C), 50% RH 5-15% 5-15%

Stability to ultravioletlight, 500 h,Fadeometer exposure Excellent Excellent

Resistance to oilsand most solvents Excellent Excellent

Ultraviolet transmission (2 mil film)400 nm 55% 82%290 nm 49% 34%210 nm 26% 6%

aTypical properties, not to be construed as sales specifications. Data based on a 1 mil dry film.

Properties of Films of METHOCEL Cellulose Ethers


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Measuring Viscosity

Certain precautions must beobserved for the accurate

measurement of the viscosity ofsolutions of METHOCELcellulose ethers because theyexhibit a nonlinear shearstress/shear rate relationship,which results in pseudoplasticviscosity behavior at mostshear rates.

Dow employs the ASTM referencemethod (D1347 and D2363) as itsstandard procedure. This methodinvolves the use of Ubbelohde

viscometers, one type for lowviscosities and another for highviscosities. The Ubbelohdeviscometer is a precision devicewhich requires only a smalltest sample.

For measuring low viscosity, theappropriate capillary tube size ischosen to obtain a flow time of 50to 150 seconds (see Table 10). Theviscometer is placed in a 20Cbath, and the length of time

required to deliver a given volumethrough the capillary tube ismeasured. The time in seconds isthen converted to millipascal-seconds (mPas). Detailedprocedures are given in currentASTM standards D1347 andD2363. The most reproducibleviscosities are obtained by coolingto 4C and holding for at leastone-half hour before testingat 20C.

Viscosity may also be determinedusing a rotational viscometer suchas the Brookfield model LVF

viscometer. When the viscosity of asolution is less than 500 mPas, theviscosity is less dependent on shear,and the solution may be regardedas near-Newtonian. The apparentviscosity of a solution of higherviscosity will be highly dependenton the rate of shear, decreasing asthe rate of shear is increased.

The rotational instrument shouldbe calibrated against standard oils.Its important to note, however,that there is no direct correlation

between Ubbelohde and Brookfieldmeasurements for non-Newtonianliquids. For details regardinganalysis methods, please contactyour local salesperson forMETHOCEL cellulose ethers.

27

Analytical Methods

Brookfield Synchrolectric viscometer, Brookfield

Engineering Co., Stoughton, MA.

Table 10: Capillary Tubes for MeasuringViscosity

Viscosity, Size of Heavy Wall Tubing,mPa.s Inside Diameter

Low viscosity

15

25

100

400

High viscosity

1,500

4,000

8,000

15,000

50,000

75,000

1.5 mm

1.8 mm

2.4 mm

3.2 mm

5.0 mm

6.0 mm

7.5 mm

10.0 mm

15.0 mm

15.0 mm


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Published Analytical Methods

Procedures for the analysis ofMETHOCEL cellulose ether

products have been standardizedunder ASTM D1372 and ASTMD2372. These and otherinformation on analysis are listedin the following references.

Methods for TestingMethylcellulose Current ASTMD1372, American Society forTesting and Materials, 1916 RaceStreet, Philadelphia, PA 19103.

Methods for TestingHydroxypropyl Methylcellulose

Current ASTM D2372, AmericanSociety for Testing and Materials,1916 Race Street, Philadelphia, PA19103.

Methoxyl and HydroxypropyISubstitution in Cellulose EtherProducts by Gas Chromatography Current ASTM D3876,American Society for Testing andMaterials, 1916 Race Street,Philadelphia, PA 19103.

Methylcellulose FoodChemicals Codex, Washington,D.C., National Academy ofSciences and National ResearchCouncil, Current Edition.

Hydroxypropyl Methylcellulose Food Chemicals Codex,Washington, D.C., NationalAcademy of Sciences and NationalResearch Council, Current Edition.

The Determination of Particle SizeDistribution of METHOCEL

Cellulose Ethers Dow MethodNo. Mc-l IA (1973).

Application of Anthrone Test toDetermination of CelluloseDerivatives in Nonaqueous Media Aldrich, J.C., Samsel, E.P., Anal.Chem. 29, 574-76 (1957).

Hydroxypropyl Methylcellulose The National Formulary, AmericanPharmaceutical Association,Washington, D.C., CurrentEdition.

Colorimetric Determination ofMethylcellulose withDiphenylamine Danzaki, Grace,Berger, Eugene Y., Anal. Chem. 31,1383-5 (1959).

Colorimetric Method forDetermination of Sugars andRelated Substances Dubois, M.,Gilles, K.A., Hamilton, J.K.,Repers, P.A., Smith, F., Anal.Chem. 28, 350-356 (1956).

Methylcellulose U.S.Pharmacopoeia, Bethesda, MD,The United States PharmacopoeialConvention, Inc., Current Edition.

Determination of Alkoxyl

Substitution in Cellulose Ethers byZeisel-Gas Chromatography Hodges, K., Kester, W.,Wiederrich, D., Grover, J., Anal.Chem. 51, 2172-2176 (1979).

28


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Material Safety Data Sheets/SafetyData Sheets for METHOCELproducts are available from TheDow Chemical Company to helpyou further satisfy your own handling,disposal, and safety needs and thosethat may be required by governmentregulations. Such information shouldbe requested prior to handling oruse. The following comments aregeneral and are not a substitute forthe detailed safety informationfound in the Material Safety DataSheet/Safety Data Sheet.

Health

METHOCEL cellulose etherproducts resemble the naturallyoccurring plant and seaweed gumsin many of their chemical, physical,and functional properties. All ofthese materials possess a basiccarbohydrate structure.

METHOCEL products have hadextensive evaluation and testing inboth acute and long-term feedingstudies in a number of species,including humans. Their many years

of use in a wide variety of fooditems attests to the safety ofMETHOCEL Premium products.

Although dust from METHOCELcellulose ether products couldconceivably cause temporarymechanical irritation to the skinand eyes under extreme conditionsand may be considered a nuisancedust if inhaled, the products areconsidered to present no significanthealth hazard in handling. Pleasereview the handling precautions

within the Material Safety DataSheet/Safety Data Sheet formore information.

Flammability

Cellulose ether products areorganic polymers that will burnwhen exposed to heat and asufficient oxygen supply. Fires canbe extinguished by conventional

means, avoiding any raising ofdust by strong water jets. Dowrecommends the use of waterspray, carbon dioxide, or powderextinguishers.

Storage

Caution: A fine dust of this materialis capable of forming an explosivemixture with air. Powder samplesshould not be exposed totemperatures above 135 to 145C.Samples may decompose and lead toa possible dust explosion. As instorage of any dusts or fine powders,good housekeeping is required to

prevent dusts in air from reachingpossibly explosive levels. Whenhandling in large quantities or inbulk, the general precautionsoutlined in NFPA 63, Preventionof Dust Explosions in IndustrialPlants, and in NFPA bulletins 68,69, and 654 are recommended.

With METHOCEL cellulose etherproducts with particle sizes of 74m or less (finer than 200 mesh),critical levels are reached at

concentrations of 28 g/m3

(0.03oz/ft3). The minimum ignitionenergy required to cause a dustexplosion is 28mJ. Static from ahuman body has about 25mJ. Thisis normally not enough energy toignite the powder.

As with any organic chemicalmaterial, METHOCEL celluloseethers should not be stored next toperoxides or other oxidizing agents.

Accidental Spills andHousekeeping

Solutions of METHOCEL celluloseethers are slippery. To preventemployee falls and injury, floor spillsof dry powder should be thoroughlyvacuumed or swept up. Any slightresidual product on the walls orfloor can then be flushed with waterinto a sewer. If the spill is a viscoussolution, it should be further diluted

with cold water before disposal.Likewise, accumulation of dustshould be avoided to controlthis hazard.

Disposal

Despite the very slow rate ofbiodegradation, cellulose etherproducts should not present anyhazard in the waste/soil compartment.Their behavior is similar to wheatflour or sawdust. Although Dowstudies using standard proceduresshowed no 5-day, 10-day, or 20-dayBOD values, activated sludge studieswith (14C) methylcellulose showed

that methylcellulose was 96%degraded or otherwise removedfrom solution in 20 days. Thus,METHOCEL cellulose ethers shouldpresent no ecological hazard toaquatic life.

Because METHOCEL celluloseether products and their aqueoussolutions present no significantecological problems, they can bedisposed of by industrial incinerationor in an approved landfill, providing

regulations are observed.Incineration should be done undercarefully controlled conditions toavoid the possibility of a dustexplosion. Customers are advised toreview their local, state, provincialor national regulations governingthe disposal of waste materials todetermine appropriate means ofdisposal in their area.

Customer Notice

Dow encourages its customers toreview their applications of Dowproducts from the standpoint ofhuman health and environmentalquality. To help ensure that Dowproducts are not used in ways forwhich they are not intended ortested, Dow personnel will assistcustomers in dealing with ecologicaland product safety considerations.Please contact us at the numberslisted on the back cover.

29

Handling Considerations


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NOTICE: No freedom from any patent owned by Seller or others is to be inferred. Because use conditions and applicable laws may differ from one

location to another and may change with time, Customer is responsible for determining whether products and the information in this document are

appropriate for Customers use and for ensuring that Customers workplace and disposal practices are in compliance with applicable laws and other

governmental enactments. Seller assumes no obligation or liability for the information in this document. NO WARRANTIES ARE GIVEN; ALL

IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE ARE EXPRESSLY EXCLUDED.

For more information, complete literature, and product samples, you canreach a Dow representative at the following numbers:

From the United States and Canada:

call 1-800-447-4369

fax 1-989-832-1465

In Europe:

toll-free +800 3 694 6367

call +32 3 450 2240

fax +32 3 450 2815

From Latin America and Other Global Areas:

call 1-989-832-1560

fax 1-989-832-1465

www.methocel.com

Toll free from Austria (00), Belgium (00), Denmark (00), Finland (990),

France (00), Germany (00), Hungary (00), Ireland (00), Italy (00),

The Netherlands (00), Norway (00), Portugal (00), Spain (00), Sweden (00),

Switzerland (00) and the United Kingdom (00).

methocel cellulose ethers- technical handbook

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