RHOPLEX CL-204 Acrylic Emulsion For Factory-Applied, Clear Topcoats Over Wood With Print Resistance and Low Microfoam Entrapment

Transcription

1 RHOPLEX CL-204 Acrylic Emulsion For Factory-Applied, Clear Topcoats Over Wood With Print Resistance and Low Microfoam Entrapment Description Certain waterborne acrylic emulsions, such as RHOPLEX CL-104, yield clear wood coatings which shed water and coalescent rapidly, resulting in excellent early print resistance properties. However, in extreme ambient conditions (temperatures approaching 100 F (38 C) and/or very low relative humidity), some of these first generation printresistant products can trap bubbles when spray applied, causing film haze and clarity loss. In contrast, RHOPLEX CL-204 emulsion is specifically engineered to minimize this microfoam entrapment by slowing the filmset process which occurs under extreme ambient conditions, while still maintaining acceptable early print resistance properties. As illustrated in Table 1, RHOPLEX CL-204 waterborne emulsion coatings achieve both of these formerly exclusive properties: low microfoam entrapment and early print resistance. Note that the ambient conditions during evaluation were among the harshest encountered for waterborne coatings, 100 F (38 C) and 25% relative humidity. Another benefit of RHOPLEX CL-204 acrylic emulsion is that the volatile organic content (VOC) of typically formulated clear topcoat lacquers is less than 2.5 pounds per gallon (less water) or 0.40 pounds of VOC per pound of polymer solids. As with all aqueous lacquers, RHOPLEX CL-204 should be carefully formulated with application conditions in mind. This brochure contains a discussion of the effect of coalescents and additives on the performance of lacquers based on RHOPLEX CL-204 emulsion.

2 Table I Properties of Low Microfoam Emulsions (Coatings 100 F {38 C} and 25% RH) Emulsion RHOPLEX CL-204 RHOPLEX CL-104 Hard, waterborne thermoplastic topcoat (competitive) Microfoam, 24 hr. dry (counted under microscope) bubbles/mm 2 * Print Resistance**, 4 hr. dry, 1 hr. print 2 psi/5 psi /4 Print Resistance, 4 hr. dry, 16 hr. print 2 psi/5 psi /5 Cold Check Resistance 1 cycle = 1 6 F/1 120 F/ 0.5 rt Stain Resistance, 24 hr. recovery water (6 and 24 hr. spot test) ethanol (1 and 6 hr. spot test) Formula 409 cleaner (1 and 6 hr. spot test) Appearance clarity grain definition Coalescents, pounds on polymer pounds Butyl Cellosolve Butyl Carbitol pass 20 cycles pass 20 cycles poor pass 20 cycles Total Substrates: stained cherry; unstained maple for cold check only. Sample preparation: conventional spray; 3 coats self-sealed; each coat 1 mil air dry; 30 minute air dry between coats. *Measured at 70x magnification where bubbles are clearly visible. **Visual scale: 10 = best

3 Typical Properties These properties are typical but do not constitute specifications. Appearance Milky-white liquid Solids content, % by weight % by volume ph 7.5 Viscosity, cp 400 Density, lb/gal Wet Dry Minimum film formation temperature, C VOC, as supplied, g/l <3.0 Freeze/thaw stability Protect from freezing Mechanical stability Passes (5 min. Waring Blender) Heat stability Passes 10 days/140 F (60 C) Formulating Guidelines Coalescents Formulations based on RHOPLEX CL-204 emulsion require the use of coalescing solvents for film formation. During manufacture, coatings should be allowed to equilibrate for at least eight hours after coalescent addition to obtain representative test results. The coalescent blend recommendations used in the starting point formulations in these notes provide excellent film formation over a broad range of application conditions. They should be followed at least for initial evaluations. Reducing the level of coalescents will allow the coating to dry more rapidly and be handled more quickly, however excessive reduction will lead to property loss in cold check, appearance, and staining characteristics. All coalescents should be premixed then added to water before addition to polymer. Premix should be added slowly and with agitation. Water-immiscible coalescents, such as propylene glycol monobutyl ether and dipropylene glycol monobutyl ether should be added to water miscible coalescents such as dipropylene glycol monomethyl ether or ethylene glycol monobutyl ether, then premixed with water and added carefully to the formulation with very agitation. Selection of the optimum coalescent system depends on drying speed requirements, ambient temperature and relative humidity, and the availability of ovens for drying.

4 Table 2 Characteristics of Coalescents Chemical Type Commercial Designations Solubility, 20 C Weight % Volatility BuAc = 100 In Water Water In Propylene glycol n-butyl ether PNB Ethylene glycol monobutyl ether EB 6 complete complete Dipropylene glycol methyl ether DPM 2 complete complete Dipropylene glycol n-butyl ether DPnB Diethylene glycol monobutyl ether DB 0.3 complete complete Ester alcohol Texanol* 0.2 insoluble 0.9 *Not recommended as a coalescent with RHOPLEX CL-204 but included for comparison purposes. Viscosity The viscosity of the CL formulation will increase with ph adjustment as well as with the addition of coalescing aids. The use of ACRYSOL RM-825 rheology modifier is recommended for further viscosity adjustment. Flatting Agents Figure 1 demonstrates the flatting efficiency of Degussa TS-100 or Syloid 7000 when added at 7% on emulsion solids. Either flatting agent can be used depending on the amount of gloss reduction desired. Coatings based on RHOPLEX CL-204 maintain excellent clarity with both of these flatting agents. Wetting Agents To prevent picture framing and improve wetting, use Surfynol 104 DPM at 0.5% - 1% on formulation solids. Wetting agent should be used sparingly because they can detract from the efficiency of RHOPLEX CL-204 in preventing microfoam entrapment. Defoamers Tego Foamex 805 at 1-2% on polymer solids is recommended for use with RHOPLEX CL-204. For best results, add defoamers after coalescents and under agitation. Mar Aids The addition of silicone-based mar aids will improve the slip and mar resistance of formulations based on RHOPLEX CL-204. Tego Glide 410 should be added at 1-2% solids on resin solids to impart mar and slip resistance. For best results, Tego Glide 410 should be reduced to 50% solids with an appropriate solvent (e.g., dipropylene glycol monomethyl ether) for ease of incorporation. Waxes Wax additives can impart mar, slip, and water resistance to the finished coating. Emulsified waxes with the smallest particle size are recommended for clarity. Powdered waxes impart haze to the finished coating due to their large particle size. Michemlube is recommended for use in CL-204 formulations.

5 Figure 1 Gloss of RHOPLEX CL-204 Coatings With Flatting Agents (7% on emulsion solids) Formulation CL Waterborne Gloss Topcoat Based on RHOPLEX CL-204 Materials Percent by Weight Lb/100 U.S. Gal Gal/100 U.S. Gal RHOPLEX CL Premix: Propylene glycol monobutyl ether Dipropylene glycol monomethyl ether Dipropylene glycol monobutyl ether Water Then add: Surfynol 104DPM ACRYSOL RM Tego Glide (50% in DPM) Tego Foamex Michemlube Add: 14% ammonia (to adjust ph to ) Water Total Formulation Constants Solids, % (wt.) Solids, % (vol.) ph Viscosity, #2 Zahn cup, seconds VOC, g/l VOC, lb/gal 1.92 HAPS lb/lb solids 0.00

6 Suppliers of Suggested Raw Materials Trade Name Type Supplier ACRYSOL RM-825 Rheology Modifier Rohm and Haas Company Dipropylene Glycol Monomethyl Ether Coalescent Arco Chemical Company Dipropylene Glycol Monobutyl Ether Coalescent Arco Chemical Company Dipropylene Glycol Monobutyl Ether Coalescent Dow Chemical USA Michemlube Wax Michelman Chemical Surfynol 104 DPM Wetting Aid Air Products & Chemicals, Inc. Tego Foamex 805 Defoamer Goldschmidt Chemical Corp. Tego Glide 410 Mar Aid Goldschmidt Chemical Corp. RHOPLEX CL-204 Thermoplastic Acrylic Polymer Rohm and Haas Company Material Safety Data Sheets Rohm and Haas Material Safety Data Sheets (MSDS) contain pertinent information that you may need to protect your employees and customers against any known health or safety hazards associated with our products. Under the OSHA Hazard Communication Standard, workers must have access to and understand MSDS on all hazardous substances to which they are exposed. Thus, it is important that you provide appropriate training and information to your employees and make sure they have available to them MSDS on any hazardous products in their workplace. Rohm and Haas Company sends MSDS on non-osha-hazardous as well as OSHA-hazardous products to both the bill to and ship to locations of all our customers upon initial shipment (including samples) of all our products (whether or not they are considered OSHA-hazardous). If you do not have access to one of these MSDS, please contact your local Rohm and Haas representative for an additional copy. Updated MSDS are sent upon revision to all customers of record. In addition, MSDS are sent on an annual basis to all customers of record. MSDS should be obtained from your suppliers of other materials recommended in this bulletin. ACRYSOL and RHOPLEX are trademarks of Rohm and Haas Company or of its subsidiaries or affiliates and are intended to designate s marketed in North and South America; the same s may be marketed in other countries, generally under other Company trademark designations. These suggestions and data are based on information we believe to be reliable. They are offered in faith, but without guarantee as conditions and methods of use of our products are beyond our control. We recommend that the prospective user determine the suitability of our materials and suggestions before adopting them on a commercial scale. Suggestions for uses of our products or the inclusion of descriptive material from patents and the citation of specific patents in this publication should not be understood as recommending the use of our products in violation of any patent or as permission or license to use any patents of the Rohm and Haas Company. Rohm and Haas, 2008 All rights reserved.