ETHOCEL Polymers FOR GENERAL APPLICATIONS

Transcription

1 ETHOCEL Polymers FOR GENERAL APPLICATIONS Strong, tough, versatile resins

2 Contents Introduction ETHOCEL Resins Structures Products Industrial Applications Room Temperature Lacquers Solvents Aromatic Hydrocarbon-Alcohol Mixtures Plasticizers Resins Pigments and Dyes Heat and Light Stabilizers Film Properties Emulsions Solvent-Free Emulsions Hot Melt Strippable Coatings Inks Gel Lacquers Premium Applications Pharmaceuticals Agriculture and Food Safe Handling of ETHOCEL Products.. 24 * Trademark of The Dow Chemical Company

3 Introduction ETHOCEL * is a trademark of The Dow Chemical Company for its family of thermoplastic cellulose ethers. These polymers have provided excellent service to industry since their commercial introduction by Dow in the mid-1930s. ETHOCEL ethylcellulose resins result from the reaction of ethyl chloride with alkali cellulose. Raw materials include cotton linters and wood pulp. The toughness, inertness, and fabrication and product versatility of these polymers have met a wide range of performance needs in sheet form, as molding and extrusion resins, as resins for pressure casting, and as resins for various coatings. While they function in many commercial applications, ETHOCEL resins are used today primarily in film forming type applications such as hot melts, gel lacquers, lacquers, adhesives, printing inks, and pharmaceutical coatings. In coatings applications, ETHOCEL resins possess performance (especially toughness) and compatibility that are unique and often economically advantageous. These tough ETHOCEL polymers dissolve readily in most organic solvents and are inert to most alkalies. They exhibit: Dimensional stability Low temperature properties Heat stability Low ash content Compatibility with plasticizers, waxes, and other resins and are essentially: Colorless Odorless Tasteless ETHOCEL resins are used commercially in these and other coatings areas: As hot melts for: Adhesives Paper coatings Pressure sensitive adhesives Strippable coatings Textile printing inks In lacquers for: Alkali resistance Bronzing Electrical insulation Fabric coating Paper coating Strippable coatings As gel lacquer coatings for: Generator field coils Glass bottles As a major binder or modifier for: Fluorescent tube coatings Glass frits Nitrocellulose lacquers Organic-solvent liquid formulations as a thickener or gelling agent Pigment print pastes Printing inks and heat transfer printing inks Sandpaper Varnishes In pharmaceuticals as: Binders Controlled release coatings Fillers Flavor fixatives Taste masks Granulation aids Protective coatings *Trademark of The Dow Chemical Company 1

4 ETHOCEL Resins Structures ETHOCEL ethylcellulose is derived from and has the polymeric backbone of cellulose, which is a naturally occurring polymer. The molecule has a structure of repeating anhydroglucose units (Structure A). Note that each anhydroglucose unit (ring) has three reactive -OH (hydroxyl) sites. Cellulose is treated with an alkaline solution to produce alkali cellulose, which is subsequently reacted with ethyl chloride yielding crude ethylcellulose (Structure B). If all three of the hydroxyl groups on each anhydroglucose unit were substituted with ethoxyl groups, the ethylcellulose would have a degree of substitution of 3. If half of the anhydroglucose units were substituted with three ethoxyl groups and the other half were substituted with two ethoxyl groups (leaving one unsubstituted hydroxyl group on every other anhydroglucose unit), the ethylcellulose would have a degree of substitution of 2.5. Structure A Cellulose Structure B Ethylcellulose 2

5 ETHOCEL Resins Products The Dow Chemical Company manufactures and markets many different ETHOCEL products to accommodate the needs of customers for different: Physical properties Uses Viscosities Solubilities ETHOCEL resins are white to light-tan granular powders with a bulk density of approximately 0.4 g/cc. The difference in physical properties of the ETHOCEL products results largely from variation in the degree of etherification. ETHOCEL ethylcellulose resins are produced in three ethoxy types (Standard, Medium and HE) that cover the range of the most useful ethoxyl content. The Standard materials have an ethoxyl content of 48.0 to 49.5%; the Medium materials have an ethoxyl content of 45.0 to 47.0%; and the HE (High Ethoxyl) materials have an ethoxyl content of 49.5 to 52.0%. ETHOCEL products are also produced and marketed in a number of different viscosities. (Viscosity increases as the length of the polymer molecule increases.) Standard ethoxyl types are also available in both Premium grades, useful in regulated applications, and Industrial grades. Medium and HE ethoxyl types are available in Industrial grades only. ETHOCEL products are correctly specified by listing the ethoxyl content (as Medium, Standard, or HE), the nominal viscosity, and the grade (Premium or Industrial). For example, ETHOCEL Standard 20 Premium cellulose ether correctly describes a Dow ethylcellulose product with: Standard ethoxyl content ( %). A nominal Ubbelohde viscosity of 20 cp for a 5% solution (in 80% toluene and 20% ethanol) measured at 25 C. (See Table 1 for ranges.) An intended use in foods or pharmaceuticals. Special viscosity or ethoxy ranges can be made available, depending on the volume requirements of an application. ETHOCEL Standard 7,10, and 100 Premium are also available in a fine particle size. These products are designated ETHOCEL Std. 7FP, Std. 10FP, and Std. 100 FP. They were designed specifically for pharmaceutical formulations in which ETHOCEL is used in an unsolubilized form. Table 1 Commercial ETHOCEL Products Product Viscosity Designation Viscosity Range, cp Medium Ethoxyl Content, % Standard Premium and Industrial grades are available. 2 Fine particle forms are available. Note: Viscosities are for 5% solutions measured at 25 C in an Ubbelohde viscometer. For Medium products, solvent is 60% toluene and 40% ethanol. For all other ETHOCEL products, solvent is 80% toluene and 20% ethanol. HE ETHOCEL Std ETHOCEL Std ETHOCEL Std. 7 1, ETHOCEL Std. 10 1,2 ETHOCEL HE ETHOCEL Std ETHOCEL Std ETHOCEL Med ETHOCEL Med ETHOCEL Med. 100 ETHOCEL Std , ETHOCEL Std. 200 ETHOCEL HE ETHOCEL HE 350 3

6 INDUSTRIAL APPLICATIONS

7 Industrial Applications Room Temperature Lacquers These are conventional lacquers in which the coating is applied at room temperature and the film is formed by evaporation of the solvent. ETHOCEL Standard 4, 7, and 10 products are typically used in lacquers: where minimum viscosity development is desired at maximum lacquer nonvolatile (solids) content; where somewhat reduced toughness can be accepted; or where compatibility with other lacquer ingredients is needed. ETHOCEL Standard 45 and 100 products are used in lacquers where greater toughness is desired combined with the greater solubility of Standard vs. Medium grades. These two ETHOCEL products are also used where maximum viscosity at minimum concentration is desirable. ETHOCEL Standard 20 cellulose ether is a natural compromise. ETHOCEL Medium 50, 70, and 100 products are used in lacquers where maximum toughness is desired and the somewhat lower solubility in particular solvents is not a problem. ETHOCEL HE 10, 200, and 350 are useful where extreme dilution with straight chain hydrocarbon solvents is desirable, and when maximum water resistance is important. Higher viscosity ETHOCEL Standard and ETHOCEL Medium products are used as thickeners for organic liquids. The following solvent and plasticizer information is helpful in selecting the ETHOCEL product with the correct ethoxyl substitution for your use. Solvents An important feature of ETHOCEL resins in lacquers is solubility in practically all types of lacquer solvents except petroleum thinners of very low kauri-butanol value and polyhydric alcohols. However, ETHOCEL HE resins with ethoxyl levels above 49.5% will tolerate extensive dilution with aliphatic thinners. This makes it possible, through the proper selection of ethoxyl type and solvent combinations, to prepare solutions suitable for any type of application from hot melt dip coatings to fast-drying knife, roller, or spray coatings. Usually several different solvent combinations can be found for any given application. Solutions of ETHOCEL resins in aromatic hydrocarbons are highly viscous; consequently only low-solids solutions are possible when these solvents are used singly. Ethanol and methanol yield solutions of ETHOCEL resins have lower viscosity than do the aromatics, but the properties of film obtained from them alone are too poor for practical purposes. However, there are mixtures of aromatic hydrocarbons with methanol or ethanol that yield solutions of ETHOCEL products having a lower viscosity than is obtainable with either solvent type used singly. These mixtures also deposit films having food strength. This is shown by the data on the toluene-ethanol solvent included in Table 3 for comparison. The lower molecular weight aliphatic esters and ketones produce solutions of ETHOCEL resins that have comparatively low viscosities and that yield films of good strength and extensibility. However, it is preferable in most cases to use these solvents with a small proportion of one of the lower molecular weight alcohols because of the lower viscosities obtainable from such mixtures (see Table 4). 5

8 Figure 1 Softening point and melting point temperatures as a function of ethoxyl content of ETHOCEL products Ethoxyl Type Designation Medium Standard Melting Point Range Temperature C Temperature F Softening Point Range Ethoxyl Content Percent Table 2 Properties of Medium and Standard Ethoxy ETHOCEL Resins Property Medium Ethoxyl Type Standard Toughness... Solubility... Tensile Strength... Hardness... Mar Resistance... Compatibility

9 Table 3 Viscosity and Film Properties of ETHOCEL Standard 10 Cellulose Ether in Single Solvents (15 g Resin in 100 cc Solvent) Solvent Solution 25 C Viscosity, cp Specific Gravity Film Properties Yield Point, kg/cm 2 Elongation, % n-butanol Butyl acetate, 90% Ethanol, formula Ethyl acetate, 99% Ethylene dichloride Methyl ethyl ketone Toluene Toluene-ethanol Too brittle to test properly. 2 Films showed orange peel. Table 4 Solvent Compositions for Minimum Solution Viscosity for ETHOCEL Resins in Common Binary Solvents Solvent Mixture Aromatic/ethanol... Aromatic/ester... Esters/ethanol... Ketones/ethanol... Aromatic naphthas/ethanol... Aliphatic naphthas/ethanol... Solvent Composition 20% ethanol No change by varying ester 20% ethanol 20% ethanol 30% ethanol 30% ethanol 7

10 Industrial Applications Solutions of ETHOCEL resins will tolerate dilution with petroleum thinners to an unusually high degree for cellulose derivatives. However, the resultant resin solution will have a higher viscosity than if it had been prepared with an aromatic solvent. (See Table 5) The most practical solvents for ETHOCEL ethylcellulose are mixtures that have been formulated to yield solutions having the lowest viscosity consistent with good film properties and that have a suitable evaporation rate. Aromatic Hydrocarbon-Alcohol Mixtures Solvent mixtures may be formulated from aromatic hydrocarbons and the lower molecular weight aliphatic alcohols to yield solutions of ETHOCEL resins having low viscosity. The effect of alcohol content on the viscosity of a solution of an ETHOCEL resin in a mixture with an aromatic hydrocarbon is seen in Figure 2. The curves show the viscosities of a 5% solution of ETHOCEL Standard 100 cellulose ether in mixtures of toluene with four, low molecular weight aliphatic alcohols. The viscosity is extremely high in toluene alone; it decreases rapidly with small percentages of alcohol, and reaches a minimum at 32% alcohol. As the alcohol content increases beyond 32%, the viscosity rises with all alcohols except methanol. This increase is greater with the higher molecular weight alcohols used. Figure 2 also shows that a lower minimum viscosity can be obtained with ethanol or methanol than with butanol. The shape and relative position of the viscosity curves of Figure 2 are changed only slightly when the concentration of the ETHOCEL resin is increased. Substitution of xylene or ethylbenzene for the toluene has little effect on the alcohol content at which the minimum viscosity is obtained, on the actual viscosity at the minimum with any one alcohol, or on the shape of the curves. Therefore, the viscosity of a solution of ETHOCEL resins will be dependent primarily on the kind of alcohol used, and on its percentage in the solvent. Lacquers containing the Medium ethoxy ETHOCEL resin are prepared from solvent mixtures richer in alcohol than is necessary in compositions made from the Standard ethoxy type. Standard ethoxy ETHOCEL products can be used in solvents containing a very low percentage of alcohol when low solution viscosity is not important, but Medium ethoxy ETHOCEL resins will not produce clear films unless the combined alcohol content is 20% to 30%. It yields solutions of minimum viscosity in mixtures of 60% to 65% aromatic hydrocarbons with 35% to 45% alcohol. The relative effect of the different alcohols on viscosity is similar to that shown in Figure 2 for Standard ethoxy ETHOCEL resins. Table 5 Effect of Hydrocarbon Solvents on Viscosity and Density of Solutions of ETHOCEL Resins at Minimum Viscosity with Ethanol Viscosity in Centipoise 25 C Solvent 5 g ETHOCEL 1 per 100 g Solution 2 5 g ETHOCEL 1 per 100 cc Solvent 5 g ETHOCEL 1 per 100 g Solution 2 5 g ETHOCEL 1 per 100 cc Solvent 70% Toluene (KB 3 105)... 30% Ethanol % Union No. 8 (KB 72)... 30% Ethanol % Troluoil (KB 36)... 30% Ethanol ETHOCEL Standard 100 Cellulose Ether. 2 5% Solution by weight. 3 Kauri-Butanol value. 8

11 Figure 2 Viscosity vs alcohol content of solvent for ETHOCEL standard 100 cellulose ether Viscosity, cp, 25 C Alcohol in Solvent, % by Volume Viscosity of 5% Solutions in Mixtures of Toluene with Alcohols 1. Methanol 2. Ethanol, Formula #30 3. Ethanol, Absolute 4. Isopropanol, 98% 5. Normal Butanol 9

12 Industrial Applications The relationship between solution and viscosity and concentration for a series of product viscosities is shown in Figure 3. (Viscosity determinations were made at 25 C in 80/20 toluene-ethanol.) From Figure 3, it is possible to select the viscosity of the ETHOCEL product required to obtain a solution of desired viscosity and concentration; it also permits the solids content at a given solution viscosity to be determined. The amount of dilution required to obtain a given solution viscosity can also be estimated from Figure 3. The data in Figure 3 suggest the possibility of using high viscosity ETHOCEL products as efficient thickeners for organic solvent-based formulations. If viscosities intermediate to those listed are required, refer to the blend chart (Figure 4). On the vertical axes are the viscosities for two different ETHOCEL products measured in any given set of units at the same conditions. On the horizontal axis is shown the percentage of one of the viscosity types of ETHOCEL in the blend. Figure 3 Viscosity-concentration chart for standard ethoxy ETHOCEL ethylcellulose Ubbelohde Viscosity, cp, at 25 C (Solutions in Toluene-Ethanol by Weight) Concentration in Weight Percent NOTE: Viscosity grade is indicated on vertical axis (5% solutions) 10

13 Figure 4 Blending chart for intermediate viscosities of ETHOCEL products Viscosity, cp Viscosity, cp For example, to produce a 5% solution of ETHOCEL resins having a viscosity of 75 cp by blending 100 centipoise with 50 centipoise material: A line is drawn connecting these two viscosities as indicated by the dashed line on the chart. The point of intersection of this line with the 75 centipoise line shows that 45% of the 50 centipoise material is required in the blend. Figure 4 can be used for blending viscosity types of ETHOCEL resins with each other, and with nitrocellulose as well. For accurate results, the viscosities of ETHOCEL cellulose ethers and nitrocellulose should be measured in the same solvent under the same conditions of temperature and concentration. In lacquers, choice of solvent is important. Table 6, page 12, shows the solubility of ETHOCEL resins in a number of common single solvents. The table, which does not list concentrations or viscosities, or all solvents for ETHOCEL resins, is intended as a general guide. Again, ETHOCEL cellulose ethers are most soluble in blends of aromatic hydrocarbons and aliphatic alcohol Percent in Blend of Resin of Viscosity on Right Hand Scale 11

14 Industrial Applications Table 6 Solvents for ETHOCEL Resins A. Hydrocarbons Solvent Solubility of ETHOCEL 1 Resins Type Name Medium ethoxy Standard ethoxy HE ethoxy Aromatic Hydrocarbons Toluene Xylene Ethyl benzene Isopropyl benzene Diethyl benzene Diphenyl ethane Hydro-Aromatic Hydrocarbons Cyclohexane Cyclohexene Methyl cyclohexane Aromatic- Naphthas Aliphatic Naphthas Petrobenzol Troluoil Apcothinner Benzosol Tolusol V.M. & P. Naval Stores Dipentene Turpentine, gum spirits Sol hazy Chlorinated Aliphatic Hydrocarbons Chloroform Carbon tetrachloride Ethylene dichloride Trichloroethylene Propylene dichloride Trichloroethane Perchloroethylene Tetrachloroethane Methylene chloride Sol hazy Chlorinated Aromatic Hydrocarbons Monochlorobenzene o-dichlorobenzene Trichlorobenzene Sol hazy Sol hazy 1 See footnote, p

15 B. Alcohols and Ethers Solvent Solubility of ETHOCEL 1 Resins Type Name Medium ethoxy Standard ethoxy HE ethoxy Monohydric Aliphatic Alcohols Methanol, anhydrous Ethanol, anhydrous Ethanol, formula 2B Isopropanol, 91% Isopropanol, 99% sec-butanol Isobutanol n-butanol Octyl (2-ethyl hexyl) alcohol, ; ; ; ; ; ; ; ; ; Sol Sol Sol Sol Monohydric Cyclic Alcohols Cyclohexanol Furfuryl alcohol Methyl cyclohexanol Tetrahydro-furfuryl alcohol Benzyl alcohol Phenyl ethyl alcohol Pine oil Polyhydric Alcohols Ethylene glycol Diethylene glycol Glycerin Triethanolamine Ether Alcohols DOWANOL* PM glycol ether DOWANOL DPM glycol ether DOWANOL EB glycol ether DOWANOL DB glycol ether 1 Solubility rated on a mixture of 2 grams of ETHOCEL in 18 cc of solvent. The following abbreviations were used to indicate the six degrees of solubility observed: Soluble, solution clear of haze and free from gels Sol hazy Soluble, solution hazy and free from gels Soluble, solution of granular nature due to presence of gels Completely gelatinized Swollen or incompletely gelatinized uble *Trademark of The Dow Chemical Company 13

16 Industrial Applications B. Alcohols and Ethers (Continued) Solvent Solubility of ETHOCEL 1 Resins Type Name Medium ethoxy Standard ethoxy HE ethoxy Ethers Ethyl ether Isopropyl ether Sol hazy Sol hazy Dioxane Morpholine n-butyl ether Phenyl ether Sol hazy Benzyl ether Sol hazy C. Esters Acetates Methyl acetate, 99% Ethyl acetate, 85-88% Sol hazy Sol hazy Isopropyl acetate sec-butyl acetate Isobutyl acetate n-butyl acetate Sol hazy sec-amyl acetate Cyclohexyl acetate Glycol diacetate Esters of Ethyl lactate Hydroxy Acids Isopropyl lactate n- Butyl lactate Methyl salicylate D. Ketones Ethers Acetone Methyl ethyl ketone ; ; Methyl isobutyl ketone ; Mesityl oxide Diacetone alcohol Cyclohexanone Methyl cyclohexanone Acetophenone 1 See footnote, p.13 14

17 Plasticizers ETHOCEL products are compatible with most of the common plasticizers. Plasticizers exert greater softening action on ETHOCEL cellulose ethers than on most other cellulose derivatives. The Medium ethoxy type requires greater concentrations of plasticizers to produce a given degree of softness than does the Standard ethoxy type. Among the plasticizers having the greatest softening effect are dibutyl phthalate, castor oil, butyl phthalyl, butyl glycolate, and butyl stearate. Among those which exert less softening effect and therefore can be used in higher concentrations are biphenyl phthalate, dicyclohexyl phthalate, cresyldiphenyl phosphate, and benzyl phthalate. In most lacquer compositions of ETHOCEL resins, 5-30% of plasticizer (based on the total solids) is sufficient to produce satisfactory flexibility. The choice of plasticizer depends on the other components of the lacquer and the temperature range or other application or use conditions, rather than on the particular ETHOCEL product. Among those plasticizers having greatest use are the phthalates, phosphates, glycerides, and esters of higher fatty acids and amides. For use in compositions that are resistant to low temperatures, long chain ester-type plasticizers are recommended. Examples of such esters are dibutyl sebacate, butyl stearate, triacetin, triethylcitrate, glycol esters of coconut oil fatty acids, and butyl ricinoleate. Resins In formulating lacquers based on ETHOCEL ethylcellulose, other resins are used to improve gloss, rubbing properties, adhesion, and resistance to certain solvents. Generally, the percentage of modifying resin is approximately equal to that of the ETHOCEL resin, and the amount of plasticizer will be about one-half that of the resin total. However, depending on the application, the ratio of ETHOCEL resin, plasticizer, and modifying resin can be varied greatly. ETHOCEL products are compatible in all proportions with most pure phenolics, modified phenolics, coumarone indenes, natural resins, processed natural resins, rosin, rosin derivatives, and long oil alkyds. There is limited compatibility with urea formaldehydes, alkyds of medium oil length, vinyl butyral polymers and vinyl acetate polymers. Small percentages of ETHOCEL ethylcellulose can be added to these resins, or small percentages of these resins can be added to ETHOCEL products, usually without causing incompatibility or haze. Approximately equal ratios of such resins and ETHOCEL resin will, however, invariably produce hazy or incompatible films. ETHOCEL resins are incompatible with most of the short oil alkyds and vinyl chloride-type polymers. On baking, certain urea formaldehyde and melamine formaldehyde resins react with ETHOCEL cellulose ethers to greatly improve solvent resistance and the softening point of the finished films. Such compositions have been used, for example, as top coats to protect a gel-lacquered surface that might come in contact with solvents that would attack the ETHOCEL resin alone. 15

18 Industrial Applications Pigments and Dyes ETHOCEL resins do not react with pigments and dyes. Lacquers based on ETHOCEL products can be pigmented by any of the usual methods and can be dyed with any dyes soluble in the solvents being used. ETHOCEL resins are an excellent pigment dispersing medium. Dispersions of this type have been made on a two-roll or three-roll mill and the resultant chips may be used to pigment both lacquers and inks. Heat and Light Stabilizers Extended exposure to heat and/or ultraviolet light can degrade lacquer ingredients. Therefore, heat and light stabilizers are often added, particularly in unpigmented formulations. Octyl phenol and butylated hydroxy phenol have performed effectively as antioxidants in this use, and 2,4-dihydroxybenzophenone has been used effectively as an ultraviolet light absorber. Generally, combinations of 1% to 2% antioxidant plus 0.5% to 1% of ultraviolet light absorber (based on lacquer solids) give adequate protection against both heat and light degradation. Pigmented formulations seldom require light stabilization. Film Properties ETHOCEL products yield a greater volume of film-forming solids per unit weight than do most other commercial cellulose derivatives, as shown in Table 7. The tensile strength and elongation properties of films of ETHOCEL resins bear a relationship to the intrinsic viscosity of the ETHOCEL product used in making the films. Films made with the higher viscosity types of Medium and Standard ETHOCEL products are stronger and tougher than those of low viscosity. This is shown in Figure 5. Figure 5 also shows that medium ethoxy ETHOCEL products possess greater hardness and toughness than do Standard ethoxy ETHOCEL products of similar viscosity. Hardness is measured by resistance to deformation; the yield points of the films shown in Figure 5 may be used to determine their relative hardnesses. An understanding of the differences between Medium and Standard ETHOCEL products is helpful in formulating coatings for maximum flexibility and toughness. At a comparable molecular weight (viscosity), the Medium ethoxy ETHOCEL product is tougher than is the Standard ethoxy ETHOCEL product. When mixtures of alcohols with aromatic hydrocarbons are used as solvent for ETHOCEL cellulose ethers without large proportions of plasticizers or other resins, the mechanical properties of the deposited film are affected by the last solvent to evaporate. This is indicated by the data of Table 3, page 7, which show that brittle films were deposited from certain alcohol-type solvents, but that strong, flexible films resulted from aromatic hydrocarbon solvents. In general, when ethanol or methanol is used to reduce solution viscosity in mixtures with aromatic hydrocarbons, the solvent mixtures should be formulated so that the aromatic hydrocarbon is the last solvent to leave the film. For example, the proportion of ethanol in mixtures with toluene, which has a somewhat slower evaporation rate than does ethanol, should not exceed 30%. With a slower-evaporating hydrocarbon, such as xylene, the ethanol content can be increased to about 40%. Emulsions For some uses, ETHOCEL ethylcellulose may be applied in a lacquer emulsion. This permits very light coatings without requiring large quantities of expensive solvents. This type of emulsion of ETHOCEL products has been used for low-weight size-coatings applied to yarns and fabrics, and for print pastes. Emulsions of ETHOCEL cellulose ethers result from the emulsification of lacquers in water. The lacquer phase of an emulsion of ETHOCEL resins consists of an ETHO- CEL product (which may or may not be modified with plasticizers, resins, dyes, or pigments) dissolved in a water-immiscible solvent. The water phase consists of an aqueous solution of an emulsifying agent, and also may contain thickeners and/or water dispersible pigments. The most useful and stable type of emulsion of ETHOCEL products is the oil-in-water type, although water-in-oil emulsions have been used for some applications. Solvent-Free Emulsions Solvent-free emulsions of ETHOCEL resins may be customer-prepared by heating and melting a blend of an ETHOCEL resin with a plasticizer. The resulting homogeneous hot mixture is then emulsified with hot water to produce an emulsion of very finely divided particles of thermoplastic material in water. Clear, colorless films result when these emulsions are cast into films and dried. Film properties may be varied by altering: Plasticizer ETHOCEL product used Ratio of plasticizer to ETHOCEL resins Drying time and temperature. 16

19 Table 7 Film Coverage Solvent Viscosity, cp Yield Point, kg/cm 2 n-butanol... Butyl acetate, 90%... Ethanol, formula Ethyl acetate, 99%... Ethylene dichloride... Methyl ethyl ketone... Toluene Toluene-ethanol Figure 5 Load-elongation curves for ETHOCEL resins Up to 50 cp cp Up to 20 cp cp 8520 Load kg / sq cm Up to 10 cp 1 Up to 100 cp 1. Standard-ethoxy ETHOCEL resin Solvent: 80 Toluene 20 Ethanol 2. Medium-Ethoxy ETHOCEL resin Solvent: 60 Toluene 40 Ethanol ALL FILMS: mm±0.002 mm Load kg / sq in Elongation, Percent 0 17

20 Industrial Applications Hot Melt Strippable Coatings These are 100% nonvolatile systems. These hot melts are used by industry primarily to protect metal parts against corrosion and damage during handling, shipment, and storage. Room-temperature parts (or objects) are cleaned and are then dipped into the hot melt. Within five seconds, a tight envelope inch thick will gel around the part. The part is then lifted from the melt and cooled. The materials used with ETHOCEL resins in a transparent hot melt strippable coating must be carefully selected because of the high temperatures ( F) encountered in the dip tanks, and because of the long heating periods involved. Heat-stable, non-volatile mineral oils, resins, and plasticizers must be chosen; antioxidants and heat stabilizers are recommended. If the coating is to be transparent, the ingredients must be compatible. The materials in a typical, strippable coating formulation could include: Component Weight Percent ETHOCEL Resin 25 Mineral Oils 50 Resins and Plasticizers 15 Heat Stabilizers 7 Antioxidants 1 Color Stabilizers 1 Waxes Inks ETHOCEL ethylcellulose resins are used in flexographic and gravure inks because they are compatible with other ink components (resins, solvents, pigments, etc.). They also function as a binder and contribute to the formation of tough, abrasion-resistant ink films upon drying. These films are pinhole free even at coating thicknesses as low as inch. In heat transfer printing, the ink is printed or deposited onto paper and then transferred with heat to fabrics (e.g., polyesters, triacetate, and acrylics). As an example, a heat transfer ink formulation could contain: Component Parts Dye 1-5 ETHOCEL Standard Solvent Thermoplastic Binder (for tack) 0-10 ETHOCEL products may also be used as the base resin in formulating solvent-free Hot-Melt Inks, which are used to print textile fabrics and novelty designs and information on T-shirts, manufacturers labels, and patterns for embroidery. A general composition is: Component Parts Castor Oil 6 Paraffin Wax 40 ETHOCEL Standard Pigments 20 Heat Stabilizer 0-10 All ingredients except the ETHOCEL resin are heated to 150 C. The ETHOCEL cellulose ether is added slowly, with agitation. A homogeneous liquid ink results when the ETHOCEL resin melts. Gel Lacquers A gel lacquer of ETHOCEL ethylcellulose is a hot lacquer composed primarily of ETHOCEL resin, plasticizer, and solvents. At or near the temperature of boiling water, the gel lacquer is a homogeneous liquid. When allowed to cool, the lacquer becomes a gelled mass resembling tough gelatin. 18

21 Dipping a cool (room temperature) object into a hot gel lacquer congeals a thick layer of the lacquer onto the object's surface. While drying, the applied lacquer shrinks, resulting in a tight-fitting, uniform plastic coating. In a single dipping, a dry coating thickness ranging from to 0.03 inch is possible. The thickness of the coating is controlled by the temperature of the object being dipped and by the composition of the lacquer. The ability to obtain unusually heavy coatings with a very few dips is a result of the phenomenon of gelation and is a primary advantage of these gel lacquers. The fundamental demand made of a gel lacquer solvent or solvent blend is that the system when hot must efficiently dissolve the ETHOCEL ethylcellulose, and yet, when cold, should have little or no effect on the resin. The less soluble nature of ETHOCEL Medium ethoxy products is a plus factor in gel lacquers. The generally tougher nature of films of ETHOCEL Medium cellulose ethers is very desirable in typical uses of gel lacquers of ETHOCEL products. Two gel lacquer formulations with ETHOCEL resin follow. The first has relatively little plasticizer and results in a tough white coating. The second is highly plasticized and gives a more extensible coating. ETHOCEL Medium, 100 cp 95.6 Paraplex G-62 plasticizer 2.4 Titanium dioxide These ingredients are dissolved at 21% solids 55/20/25 xylene/aliphatic petroleum thinner/dowanol PM glycol ether. Application temperature is 200 F. Approximately 20 mils of dry film are applied per coat. ETHOCEL Medium, 100 cp 70.0 Paraplex G-62 plasticizer These ingredients are dissolved at 23% solids in 75/25 xylene/aliphatic petroleum thinner. Application temperature is 200 F. Approximately 20 mils of dry film are applied per coat. Such lacquers typically also contain heat and light stabilizers, modifying resins, and pigments. Gel lacquers are prepared by heating the solvents to the proper temperature followed by addition of ETHOCEL ethylcellulose with moderate agitation. 19

22 PREMIUM APPLICATIONS

23 Premium Applications Pharmaceuticals ETHOCEL Premium polymers are recognized and used globally for many different functional purposes in scores of pharmaceutical products. ETHOCEL Premium polymers are most frequently used in controlled release solid dosage formulations. They are also useful as granulation binders, as film-formers, to improve tablet integrity and appearance, and in taste masking of bitter actives. ETHOCEL Premium polymers meet the requirements of the Food Chemical codes, the U.S. National Formulatory (NF), the Japanese Standards of Pharmaceutical Ingredients (JSPI), and the European Pharmacopia (EP). Refer to the product s Certificate of Analysis for a statement of compliance to the current version of each of these regulatory documents. Granulation Premium grade ETHOCEL products are often used for solvent granulation of water-sensitive materials. Tablets made with ethylcellulose-granulated materials are strong and have good dissolution properties. ETHOCEL resins may also be used for extrusion granulation because of the thermoplastic nature of ethylcellulose. Dissolution times may be extended or modified by varying the amount of ETHOCEL resin in a granulation or by adding water-soluble binders to the granulating fluid containing the ETHOCEL cellulose ether. Tablet Coating ETHOCEL products have long been used as a solvent-based tablet coating. ETHOCEL resins form strong films with good adhesion. Because ethylcellulose is water insoluble, it is often used in conjunction with other water and organic-solvent soluble polymers such as METHOCEL* cellulose ethers (hydroxypropyl methylcellulose). Sustained or delayed release coatings can be achieved by varying the ratios of ETHOCEL and METHOCEL products. Examples of film dissolution rates are given in Table 8. The technology of making and spraying solvent-free emulsions of ETHOCEL resins (as discussed on page 16) has been used in the pharmaceutical industry to coat tablets with ethylcellulose in the absence of volatile, flammable, organic solvents. Encapsulation While it is not a true encapsulation process, timed-release capsules are often manufactured by spraying solutions of METHOCEL and ETHOCEL cellulose ethers onto small beads of active ingredients. Wide variations of release rates or release patterns can be achieved by varying these polymer ratios and coating weights. ETHOCEL resins also are used in a coacervation process to microencapsulate particles. The microencapsulation of particles in a boiling cyclohexane-ethocel resin mixture is described in the NCR process (U.S. Patent No 3,567,650) and is used in some pharmaceutical applications. Tablet Binding ETHOCEL products also are used as tablet binders in dry compression granulation or direct compression. The use of small amounts of ETHOCEL resins as a tablet binder does not adversely retard the tablet dissolution rate. The ETHOCEL cellulose ether should be dissolved in a solvent (or solvent blend) at approximately 10% solids. A plasticizer (e.g., glycerine) may be added to the mixture. The following solvents are recommended: Toluene and ethanol blend Methylene chloride and ethanol blend Chloroform and ethanol blend Ethyl lactate and ethanol blend Methyl salicylate and ethanol blend Methyl salicylate Table 8 Films of ETHOCEL and METHOCEL Cellulose Ethers Film Composition METHOCEL E50 Premium Cellulose Ether 25% 60% 75% ETHOCEL Standard 45 Premium Cellulose Ether 75% 40% 25% Solubility Time, hours *Trademark of The Dow Chemical Company 21

24 Premium Applications Selecting the Right ETHOCEL Polymer Although certainly not all-inclusive, Table 9 provides starting point recommendations for various formulating technologies. Table 9 Selection of ETHOCEL Polymers for Pharmaceutical Applications Application ETHOCEL Polymer Controlled release coatings Micro-encapsulation ETHOCEL Standard 7, 10, or 20 Premium ETHOCEL blended with METHOCEL E5 or E15LV Premium cellulose ether ETHOCEL Standard 45 or 100 Premium Tablet coating Granulation Binder/direct compression ETHOCEL Standard 7, 10, or 20 Premium ETHOCEL Standard 10, 20, or 45 Premium ETHOCEL Standard 7 FP Premium, 10 FP Premium, or 100 FP Premium 22

25 Premium Applications Agriculture and Food Ethylcellulose is listed in 40 CFR as a substance Exempt from the Requirement of a Tolerance for use in pesticide formulations. This provision combined with the tablet coating and encapsulation (see page 21) capabilities of ETHOCEL resins makes them a logical choice for encapsulation of pesticides to provide timed-release or delayed-release features. ETHOCEL cellulose ethers may also be used in seed coating, for example, to retard water up-take by the seed, thereby delaying germination (as in autumn planting of spring wheat). Regulatory Status ETHOCEL resins are odorless, tasteless, and film-forming and are therefore used in many food applications. The specifications applicable to these food and drug uses are defined in the Food Chemicals Codex. ETHOCEL Premium resins meet specifications of the compendia. ETHOCEL Premium grade resins meet the requirements of the following FDA regulations: 21 CFR 73.1 Color additive for foods. Diluent in inks for marking food supplements in tablet form, gums and confectionaries; inks for marking fruits and vegetables; and as a diluent in color additive mixtures for coloring shell eggs Color additive for drugs. Diluent used in ink to mark ingested drugs and externally applied drugs Certain direct food uses. As binder and filler in dry vitamin preparations; as a component of protective coatings for vitamin preparations and mineral tablets; and as a flavor fixative in flavoring compounds Adhesives. Generally recognized as safe (182.90) Resinous and polymeric coatings Components of paper and paperboard in contact with aqueous and fatty food. Generally recognized as safe (182.90) Components of paper and paperboard in contact with dry food. Generally recognized as safe (182.90) Closures with sealing gaskets for food containers. (Cross reference to ) Substances generally recognized as safe. Substances migrating to food from paper and paperboard products. Ethylcellulose Certain uses in animal feed. As a binder or filler in dry vitamin preparations to be incorporated into animal food. 1 United States Code of Federal Regulations 23

26 Safe Handling of ETHOCEL Products Material Safety Data Sheets on ETHOCEL products are available from the Specialty Chemicals Department to help customers further satisfy their own handling needs and those that may be imposed by regulatory agencies. This information should be requested and read PRIOR to handling or use of the product. The materials used in formulating with ETHOCEL resins solvents in particular may constitute separate hazards from toxicity or flammability. Be certain to get handling and safety recommendations for each such product from its supplier. Health Considerations ETHOCEL cellulose ether products are thermoplastic polymers having a polymer backbone obtained from cellulose, a naturally occurring carbohydrate polymer. Dusts from ETHOCEL cellulose ether products could conceivably cause temporary mechanical irritation to the eye under extreme conditions. They are considered as nuisance dusts when inhaled. However, the products are considered to present no significant or unusual health hazard to personnel in normal industrial handing. As a result, no special precautions need be observed to handle the products other than the possible need for a local exhaust system to control dust during opening and dumping of bags. Combustibility Dusts or fine powders of ETHOCEL products in air can reach explosive levels and care must be taken to prevent this. ETHOCEL products are organic materials and will burn under the right conditions of heat and oxygen supply. ETHOCEL resins will melt upon exposure to an open flame. Once melted and ignited, these resins will support combustion. Fires can be extinguished by any available extinguishing agent. Spills To prevent accidents, good housekeeping requires that spills of ETHOCEL products should be thoroughly vacuumed or swept up. For small spills of liquid formulations of ETHOCEL resins, a solid absorbent should be used to absorb the liquid. Any solvents should then be allowed to evaporate, and the absorbent, containing the ETHOCEL resin, should be disposed of via approved landfill or incineration. For large liquid spills, appropriate diking precautions should be taken until the solution can be collected for proper disposal. In liquid solution spills, solvents may present significant health and fire hazards. Disposal ETHOCEL cellulose ethers are not water soluble and do not biodegrade in aquatic environments. The resin should, therefore, present no ecological hazard to aquatic life. ETHOCEL products present no significant ecological problems, and therefore can be disposed of by burning in an adequate incinerator or by burial in an approved landfill. Incineration should be done under carefully controlled conditions to avoid the possibility of a dust explosion. If it is necessary to dispose of a formulation that includes ETHOCEL products, it is recommended that the suppliers of all formulation ingredients be consulted before deciding on a suitable disposal method. In disposal of any wastes, be certain all applicable federal, state, and local regulations are met. Storage/Handling The shelf-life for ETHOCEL is a nominal two years. ETHOCEL products should be stored at temperatures not exceeding 90 F (32 C) in a dry area away from all sources of heat. In storage or use, good housekeeping is required to prevent dusts or fine powders of ETHOCEL resin from reaching explosive levels in air. When handling ETHOCEL cellulose ethers in large quantities or in bulk, general precautions outlined in NFPA 1 No. 63, Fundamental Principles for the Prevention of Dust Explosions in Industrial Plants, are recommended. For additional information, see NFPA nos. 68, 69, and 654. As with any organic chemical material, ETHOCEL cellulose ethers should not be stored next to peroxides or other oxidizing agents. Premium grades of ETHOCEL products are intended for use in foods, in foodcontact, or in pharmaceuticals. As such, these products are subject to the Good Manufacturing Practices (21 CFR 110, 21 CFR 210, and 21 CFR 211) of the Food and Drug Administration. Materials in this use should not be stored near hazardous or non-food chemicals. To prevent odor transference, ETHOCEL Premium Polymers should not be stored adjacent to any foul smelling material. 1 National Fire Protection Association Battery March Park Quincy, MA

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28 Customer notice Dow encourages its customers and potential users of Dow products to review their applications of such products from the standpoint of human health and environmental quality. Dow personnel will assist customers in dealing with product safety considerations. Your Dow sales representative can arrange the proper contacts. Dow product literature, including Material Safety Data Sheets, should be consulted prior to use of Dow products. These may be obtained from your Dow sales representative or sales office. For more information, complete literature, and product samples you can reach a Dow representative by calling the following phone numbers. From the United States and Canada call From Mexico call In Europe FAX + 31/ call + 31/ Or you can contact us on the Internet at ETHOCEL@DOW.COM 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 Customer s use and for ensuring that Customer s 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. Printed in U.S.A. *Trademark of The Dow Chemical Company Form No GW Published February 1998 McKAY00000/