RHOPLEX WL-100 Emulsion Copolymer For High-Gloss Plastic Coatings With Excellent Adhesion Description RHOPLEX WL-100 resin is an acrylic-styrene copolymer designed for high-gloss, high-doi (Distinctness of Image) waterborne plastic coatings where an attractive appearance and excellent dry and wet adhesion are important considerations. The favorable colloidal stability (robustness) of RHOPLEX WL-100 resin accommodates a broad range of formulation types and formulation process techniques, providing the formulator with a versatile binder for a variety of applications. Robustness, along with 50% weight solids, allows the formulator to achieve volume solids above conventional waterborne binders. Key Features High gloss and DOI easily achieved Excellent dry (including initially after bake) and wet adhesion to a variety of plastics Wide formulation latitude and applications Favorable formulation cost/performance balance Can produce hard films Typical Physical Properties These properties are typical but do not constitute specifications. Appearance Solids, % by weight 49 to 50 Milky-White liquid ph 8.5 to 9.5 Viscosity, Brookfield, cp 50 to 200 Wet Density, lbs./u.s. gal. 8.73 Dry Bulking Value, gal./lb. 0.115 MFFT, C 48 Formulating Optimum application and dry film performance properties of a protective coating depend critically on the proper choice and level of formulation ingredients. The following formulation guidelines are intended to demonstrate the versatility of RHOPLEX WL-100 resin, as well as to provide the formulator with information to expedite the evaluation of the product. Coalescents and Plasticizers The MFFT of RHOPLEX WL-100 resin is well above (~48 C) most application temperatures and consequently requires the use of coalescing solvents and plasticizers to form films with optimum physical properties. The type and level of coalescing solvents and plasticizers depend on the application and end use. Coalescing solvents found useful in formulations based on RHOPLEX WL-100 resin include the partially watersoluble alkyl ethers of propylene and dipropylene glycols. A specific example is dipropylene n-butyl ether (Dowanol DPnB) used at about 25% (w/w) based on polymer solids (BOP) when used alone. Substantially reduced levels (<10% BOP) of DPnB can be used if a non-volatile water-immiscible plasticizer (see below) is part of the coalescing package. Dowanol DPnB and other partially and completely water-miscible, polymer-phase, (see DB below) coalescing solvents effectively interact and swell RHOPLEX WL-100 latex particles. Latex particle swelling can provide a useful method of increasing application viscosity. Other examples of alkyl ethers of (di) propylene glycol include propylene glycol n-butyl ether (PnB) and dipropylene glycol n-propyl ether. However, due to the fast evaporation rate of PnB, inclusion of a slower evaporative coalescing solvent or non-evaporative plasticizer may be necessary for optimum film formation.
To a much lesser degree, the completely water-soluble alkyl ethers of (di)ethylene glycol (e.g., Dowanol DB and EB) provide adequate film formation and require much higher (> 25% BOP) use levels for good film formation. In general DB (or EB) should be used as part of a coalescing package rather than alone. Other coalescing solvents found useful for coatings based on RHOPLEX WL-100 resin include the alkyl acetates (nalkyl or branched) and Texanol. Although very effective coalescing solvents for RHOPLEX WL-100 resin, the nearly complete water immiscibility of Exxates 800 (and higher alkyl members of the Exxate family) and Texanol do not cause the same extent of latex particle swelling as Dowanol DPnB. The use of a "permanent" plasticizer(s) has been found to provide beneficial properties to coatings based on RHOPLEX WL-100 resin. These include enhanced impact resistance, flexibility, and reduced surface dry time. Reduced surface dry time can be important in applications involving recoat and gloss and film clarity retention after exposure to water. Permanent plasticizers found useful in formulations based on RHOPLEX WL-100 resin include Santicizer 160, dibutyl phthalate, and KP-140. Pigments, Dispersants, Wetting Aids The choice and level of pigments, dispersants, and wetting aids can have a profound effect on the appearance and barrier properties of cured films. RHOPLEX WL-100 resin can be formulated into coatings with a wide range of pigment levels (PVC) and types, including both inert and reactive pigments. The stability of RHOPLEX WL-100 resin to shear allows the formulator, in some cases, to prepare pigment dispersions in the presence of resin. This potential advantage allows for paints with increased volume solids. TAMOL 681 and TAMOL 165 pigment dispersants at levels of approximately 0.75% to 2% on pigment solids have been found to produce coatings with a good balance of high gloss and good barrier properties. Pigment wetting, non-ionic, low-foaming surfactants, such as Triton CF-10, Igepal CTA-639W, and Surfynol 104A, have been used successfully to prepare pigment dispersions at levels of approximately 1 to 5 lbs./100 gal. of formulation. Defoamers Various surface active ingredients used in waterborne paint formulations, such as dispersants, wetting aids, latex surfactants, and some coalescents may generate or stabilize foam during the manufacture or application of paint. In general, a defoamer should be evaluated for its effectiveness and long-term efficacy in each formulation, since the type and level of the surface-active ingredients will vary. Examples of defoaming agents found useful in formulations based on RHOPLEX WL-100 resin are Byk -002, Byk-024, Tego Foamex 1488, and Dehydran 1620. Viscosity Control and Thickening Agents In some cases, paints based on RHOPLEX WL-100 resin may not require the use of an external thickener. As mentioned previously, glycol ethers such as Dowanol DPnB and DB swell RHOPLEX WL-100 latex particles, increasing their effective volume and increasing paint viscosity. This self thickening is highly dependent on formulation volume solids with higher volume solids showing the greatest response. The use of ammonia or other amines can further increase viscosity. However amines that evaporate slower than ammonia can reduce dry time and prolong or increase film water sensitivity. High molecular weight HEUR thickeners, such as ACRYSOL RM-12W are recommended for thick film applications to control sagging and mud cracking. Depending on other formulation ingredients, the rheology modifier level can vary from 1 to 20 lbs./100 gal. of paint with high levels of coalescent and surfactants requiring higher levels of thickener. Other HEUR thickeners found useful in formulations based on RHOPLEX WL-100 resin include ACRYSOL RM-2020NPR for increasing viscosity at high shear and ACRYSOL RM-8W for increasing viscosity at medium shear rates. Performance Comparison RHOPLEX WL-100 was compared in performance to Competitive Binder A, a waterborne styrene-acrylic long used for decorative general industrial finishing, on four typical plastic substrates: ABS, polycarbonate, Noryl and high impact polystyrene. The formulation was a low PVC, high gloss black lacquer, detailed below with a description of application conditions.
Low PVC Black Gloss Coatings Used for Comparison on Plastics Substrates Ingredient RHOPLEX WL-100 Competitive Binder A RHOPLEX WL-100 383.80 Competitive Binder A 421.20 TegoFoamex 1488 0.10 0.10 Butyl Cellosolve 79.70 79.70 Butyl Carbitol 19.90 19.90 Dibutyl Phthalate 11.40 11.40 Water 74.00 74.00 UCD 1625E 22.10 22.10 TegoWet KL-245 1.70 1.70 Water TOTAL 592.70 630.10 Total solids, % ph** 8.11 8.40 LVF Brookfield Visc., 30 rpm, cp 560 150 % cosolvent on binder dwt 57 57 **adjusted with 14% NH 4 OH NOTE: Each coating was applied to plastic panels, air dried for 5-10 minutes and baked at 60 C for 30 minutes. Dry film thickness was in the range 1.2-1.4 mils. Plastic substrates evaluated were Cycolac AR 3501 (ABS), Lexan EM 1210-754 (polycarbonate), Noryl FN 190 and Styron 421 W (HIPS). Appearance Comparison RHOPLEX WL-100 Competitive Binder A 20 Gloss 89.8 85.1 60 Gloss 93.3 92.2 DOI 80 80 Pencil Hardness HB HB Testing was done on the ABS substrate. Both binders are characterized by excellent gloss and appearance with RHOPLEX WL-100 having the edge. Dry Adhesion Comparison Plastic RHOPLEX WL-100 Competitive Binder A ABS Excellent Good Polycarbonate Excellent Excellent Noryl Excellent Initial: Poor Aged: Excellent High Impact Polystyrene (HIPS) Excellent Excellent Testing was done initially (5-10 minutes) after bake and after three days at room temperature. The test was crosshatch adhesion. While both binders are recommended for plastic adhesion, only the RHOPLEX WL-100 gave consistently excellent adhesion over the range of plastics whether testing was done initially after bake or several days later.
Wet Adhesion Comparison Plastic RHOPLEX WL-100 Competitive Binder A After Water Immersion ABS Excellent Excellent Noryl Excellent Excellent After Humidity Exposure ABS Excellent Excellent Noryl Excellent Excellent Water immersion was for 24 hours at room temperature. Humidity exposure was for 100 hours at 100 F at 100% relative humidity. Crosshatch adhesion was evaluated right after exposure and wiping the panel and after three hours recovery. As in dry adhesion, RHOPLEX WL-100 gave consistently excellent adhesion over the range of plastics. Solvent Rub Resistance Comparison RHOPLEX WL-100 Resistance to Attack Color Transfer Competitive Binder A Resistance to Attack Color Transfer MEK Poor Heavy Poor Heavy Isopropanol Fair Heavy Fair Heavy 95% Ethanol Poor Moderate Poor Moderate Testing was done on the ABS and Noryl substrates. Both of these styrene acrylics, as thermoplastic binders, are significantly attacked by solvent rubbing. 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 for all its products, whether or not they are considered OSHA-hazardous, to both the bill to and/or ship to locations of all its customers upon initial shipment, including samples. 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 annually to all customers receiving products deemed hazardous under the Superfund Amendments and Reauthorization Act. MSDS should be obtained from your suppliers of other materials recommended in this bulletin. Rohm and Haas Company is a member of the American Chemistry Council and is committed to ACC s Responsible Care Program.
ACRYSOL, RHOPLEX, and TAMOL are trademarks of Rohm and Haas Company or of its subsidiaries or affiliates and are intended to designate goods marketed in North America; the same goods 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 good 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, 2007 All rights reserved.