NACURE DNNDSA Catalysts

Transcription

1 DNNDA Catalysts This special issue focuses on the unique performance characteristics of Dinonylnaphthalene Disulfonic Acid Catalysts (DNNDA) offered by King Industries for use in baked amino crosslinked coatings. A variety of acid catalysts are currently available to promote reactions of thermoset coatings, adhesives and inks. Although most sulfonic acid catalysts will accelerate the reaction of hydroxyl functional resins with amino resin crosslinkers, the structural differences between these acids can have a significant influence on final performance properties. Dinonylnaphthalene disulfonic acid, commonly referred to as DNNDA, is unique in both structure and performance, offering superior adhesion and intercoat adhesion, strong resistance to impact and overbake embrittlement, humidity, detergents and salts. A broad range of baked amino crosslinked formulations can benefit from catalysts based on this acid, including coatings for automotive, coil, appliance, wood and paper substrates, coatings applied to metals used for container and general industrial applications, and in specialty thermoset adhesives and inks. Key DNNDA Catalyst Products Acid Catalyst DNNDA TABLE OF CONTENT HO 3 C 9 H 19 H 19 C 9 O 3 H Due to its hydrophobic nature, DNNDA is not easily washed out of the film when exposed to moisture and corrosive salts and does not leave voids compared to more hydrophilic water soluble acids. Although hydrophobic, DNNDA can readily be dispersed into many waterborne formulations and is often the catalyst of choice for waterborne primers. King Industries offers a variety of catalyst choices based on DNNDA, and several products are specifically designed for aqueous formulations. Introduction to DNNDA Catalysts Blocked Catalyst Blocked Catalyst Blocked Catalyst Performance Advantages of DNNDA 2 tandard DNNDA Products 6 Formulating Information 6 Catalyst election Chart by Application 8 XC-194 Blocked Catalyst Contact Information 8 KING DA 2013

2 DNNDA Performance Unique performance advantages found with DNNDA include superior adhesion, salt corrosion resistance and detergent resistance. I. Advantages High solids polyester formulations catalyzed with DNNDA consistently show better adhesion and impact resistance (reduced embrittlement) in comparison to pta catalyst. This 88% solids solvent based clearcoat (Table 2.1) demonstrates superior adhesion and impact resistance performance using DNNDA catalyst. Amine-blocked DNNDA (Table 2.2) show improved adhesion on steel substrates at two different cure schedules. Table 2.1 DNNDA vs. pta High olids Polyester/HMMM K-FLEX 188/Cymel 303 1, Cure: 15 C DNNDA NACURE pta 40% in Ispropanol Pencil Hardness 2-3H 2-3H Crosshatch, % Impact Resistance (80 in./lb.) Reverse Direct >80 > Table 2.2 Amine Blocked DNNDA vs. pta High olids Polyester/ HMMM K-FLEX 188/Cymel 303, 1 mil (25 micron) dry film thickness Cure chedule: 15 minutes@150 C NACURE pta 25%, Amine Pencil Hardness H-2H 2-3H Iron Phosphated Cold Rolled teel 96% 24% Cure chedule: 20 minutes@125 C Pencil Hardness H-2H H-2H Iron Phosphated Cold Rolled teel 84% 40% A high solids polyester clearcoat catalyzed with amine-blocked DNNDA demonstrates dramatic improvements in adhesion to aluminum in comparison to the same formula catalyzed with a blocked dodecylbenzene sulfonic acid (DDBA), as shown in Table 2.3. Table 2.3 DNNDA vs. DDBA High olids Polyester/HMMM Polymac /Resimene 747 3, Cure: 15 minutes@135 C 0.91mil (22.7 micron) dry film thickness DNNDA NACURE DDBA 25%, Amine Pencil Hardness H-2H H-2H Pendulum Hardness to Untreated Aluminum 90% 20% 1 Cymel Cytec Industries, Inc. 2 Polymac PCCR UA 3 Resimene INEO Melamines Inc. 2

3 II. Corrosion Resistance Advantages An amine-neutralized waterborne acrylic/hmmm clearcoat demonstrates advantages of DNNDA catalyst over a more hydrophilic pta catalyst. The formulation contains sufficient carboxylic acid functionality to provide reactivity with the melamine crosslinking resin. However, catalyst addition increases the crosslinking efficiency between acrylic and amino resins, with higher crosslink density evidenced by higher resistance to MEK solvent rub tests. improves adhesion between the steel substrate and scribed film, and its hydrophobic nature protects the film from salt fog penetration and yields improved corrosion protection. Table 3.1 DNNDA vs. pta - WB Acrylic/HMMM Acrysol W-68 1 /HMMM, Cure: 15 minutes@150 C mil ( micron) dry film thickness No Catalyst DNNDA pta 40% in Isopropanol Pencil Hardness H-2H H-2H H-2H MEK Rubs (2X) , % alt pray Resistance, (ATM B117), 150 hrs. mm. Creepage Blister Rating A high solids solventborne polyester/acrylic enamel catalyzed with blocked DNNDA catalyst also demonstrates superior corrosion resistance. The improved adhesion benefits of DNNDA catalysis are demonstrated by the minimal creepage along scribed films and elimination of blister formation. Table 3.2 Blocked Catalyst Comparison H Polyester/Acrylic/HMMM K-FLEX 188/ACRYLIC/HMMM, Cure: 30 minutes@107 C 0.9 mil (22.5 micron) dry film thickness Photo 3.1 alt pray Resistance (ATM B117) Vs. Blocked pta 260 Hours Polyester Coil Coating Pencil Hardness DNNDA pta Amine 25% DDBA Amine 25% H-2H H-2H H-2H MEK Rubs (2X) >100 > alt pray Resistance, (ATM B117), 250 hrs. mm. Creepage Blister Rating F F9 1 Acrysol W-68 - Dow Chemical 3 KING DA 2013

4 III. Detergent Resistance Advantage Coatings that require resistance to detergents such as indoor appliance coatings will also benefit with the use of a DNNDA catalyst. Covalently blocked acids are recommended for higher cure temperature applications such as coil (precoated metal) and can coatings. The covalent blocking group attached to the acid will take part in crosslinking with melamine resin present in the formulation and become a contributor to the film network. Detergent resistance advantages of 3483 are demonstrated in a coil coating enamel based on a high molecular weight polyester and HMMM. After detergent exposure the films that contained an amine blocked pta catalyst were densely blistered, while the enamels catalyzed with 3483 were resistant and blister free. Resistance to corrosion creepage from scribed panels exposed to salt spray also demonstrates that the adhesion benefits of this product can lead to additional film resistance advantages. Table 4.1 Blocked DNNDA Vs. Blocked pta Polyester/HMMM Coil Coating pta/amine 3483 Pencil Hardness HB HB Konig Hardness (cycles) Detergent Resistance (ATM D2248) Blister density Dense No blisters Blister size 2 10 Gloss (20 C) Initial After Detergent Test NA 60 alt pray Resistance (ATM B117) Creepage, mm. 3 <1 Blister density M M Blister size 4 4 Another study compared two covalently blocked acid catalysts in the same polyester/hmmm formula. A covalently blocked pta catalyst was tested in comparison to covalently blocked DNNDA catalyst 3483.The coating catalyzed with 3483 shows no attack from the detergent solution exposure. The pta catalyst once again reduces film resistance to detergents, evidenced by large and dense blister formation. DNNDA catalysts are well suited for coatings that require long term resistance to detergent exposure. Table 4.2 Covalantly Blocked Catalyst DNNDA Vs. pta Polyester/HMMM 3483 Covalently Blocked pta Pencil Hardness HB HB Pendulum Hardness Detergent Resistance Blister Ranking 10 3MD 4

5 IV. Improved Conductive Properties Another interesting characteristic of a DNNDA catalyst is its electrostatic properties. The unique conductive properties of DNNDA can be useful in formulating conductive inks, conductive polymers, and conductive primers for example. Despite their relatively low use levels, catalysts will influence the total electroconductive nature of the formulation. If electrostatic spray equipment is used to apply the coating, an optimum conductive range is built into the system for high coverage efficiency. When a polar sulfonic acid catalyst is used in these systems the total conductivity of the formulation will increase, and may result in poor application coverage manifested by poor film appearance. With the less polar DNNDA, the conductivity change will be smaller, supporting good transfer efficiency between spray head and the metal substrate. Graph 5.1 shows lower conductivity with DNNDA catalyst. Each acid was diluted in water to a 1,000 ppm concentration. Graph 5.1 Acid Conductivity, 1000 ppm p-ta DNNDA V. Catalysts Resistant to Pigment Adsorption µ/cm King Industries offers several catalysts based on DNNDA derivatives that help the formulator avoid interactions between acid catalyst and pigments. ystems containing pigments with high ph values such as fillers and anticorrosive pigments may require catalysts even more resistant to their neutralizing effect. XC-194K is designed for such conditions. MEK Rubs (2X) Graph 5.2 torage tability - 50 C Weeks 7 Weeks 14 Weeks 21 Weeks 28 Weeks Examination of a polyester/ HMMM coil coating enamel containing a highly basic anticorrosive pigment show XC-194K Catalyst Blend longer storage stability using XC-194K in comparison to a recommended catalyst blend composed of epoxy neutralized phosphoric acid and dodecylbenzene sulfonic acid. Graph 5.2 demonstrates this advantage, showing good solvent resistance after weeks of storage at elevated temperature. 5 KING DA 2013

6 tandard Products Available To improve storage stability of one component acid catalyzed formulations, acid catalysts are available in a pre-neutralized or blocked form, using amines or polymer components as the neutralizing agents. The product line offers several unique blocked versions of DNNDA catalysts that are designed to provide the following benefits: Faster cure Good balance of cure, stability and film performance Good compatibility Hydrophobicity Less adsorption on basic pigments Excellent adhesion and intercoat adhesion Table 6.1 Acid Catalyst % Active Diluent(s) Acid # Gardner Color Minimum Cure** 55 Isobutanol max. RT Amine & Covalent Blocked Catalysts ph (1:1)* 25 Isobutanol Isopropanol max. 90 C 25 Isobutanol Isopropanol max. 120 C XC-194K 20 Hydrocarbon N/A 10 max. 140 C Xylene N/A 10 max. 120 C * Measured after mixing catalyst as supplied with deionized water 1:1 ratio by weight ** Cure schedule: 30 minutes - Resin/Urea (60/40 ratio) Catalyst Incorporation and olubility Considerations everal important considerations should be taken into account whenever acid catalysts are used. Proper incorporation methods and diluent selection that best matches the catalyst solubility characteristics should be considered. Incorporation of a strong acid generally requires good mixing in order to prevent localized ph shock and potential formation of salts or complexes with the catalyst that can result in an insoluble compound or reduce its catalytic activity. products are supplied in diluents for ease of addition, and many users dilute the catalyst further with additional solvents used in the formulation before catalyst incorporation. In addition, diluents present in the formula will often dictate the use of one catalyst over another. DNNDA generally prefers solvents with stronger polarity. Guidelines recommend that the total solvent blend has a solubility parameter of 9 or greater using Hansen cale values to achieve the best compatibility. 6

7 The solvent blends in Table 7.1 demonstrate this point effectively. olvent blend #1 has a total solubility parameter less than 9, and the limited solubility of under these conditions resulted in catalyst precipitation. Reducing the level of acetate solvent and increasing the level of more polar alcohols raises the total solubility parameter of solvent blend #2, resulting in a compatible mixture with the catalyst. Table 7.1 olubility Parameter Calculated olvent Blends (%) by Weight olubility (1% ) olvent Blend #1 MIBK (70) MEK (10) 2-EEA (15) n-butanol (5) Insoluble olvent Blend #2 MIBK (70) MEK (10) 2-EEA (8) n-butanol (8) Isobutanol (4) oluble Table 7.2 olubility In Common olvents olvent Water I Glycols Glycol Esters Alcohols Esters P P I Ketones P P P Aromatic Hydrocarbons I I I Aliphatic Hydrocarbons I I I I KEY: 3327 = oluble, P= Partially, I= Insoluble, NR= Not recommended 3483 I NR Any evaluation of acid catalysts should include a ladder study of addition levels to determine the best balance of cure speed and final product performance. DNNDA has an equivalent weight of 270 based on two sulfonic acid groups per molecule. This should be considered when comparing this acid to monofunctional sulfonic acids. 7 KING DA 2013

8 Catalyst election Chart by Application METAL UBTRATE PRIMER TOPCOAT olventborne Waterborne CAN COIL, APPLIANCE & GENERAL INDUTRIAL olubility olventborne Waterborne olventborne Waterborne XC-194 High ph Pigments & Package tability Moisture Resistance & tability Moisture Resistance Package tability & AUTOMOTIVE PRIMER TOPCOAT: Basecoats & Clearcoats PLATIC olventborne Waterborne olventborne olventborne Waterborne Intercoat olubility & & olubility & Wood & Paper Coatings, Adhesives (ealants) & Inks olventborne Waterborne For Additional Information Please visit our web site: KING DA 2013 WORLD HEADQUARTER King Industries, Inc. 1 cience Rd. Norwalk, CT Phone: Fax: coatings@kingindustries.com AIA-PACIFIC OFFICE ynlico Tech (Zhongshan) Co., Ltd. 106 Chuangye Building, Kang Le Ave. Torch Development Zone, Zhongshan, China Phone: Fax: EUROPEAN OFFICE King Industries, International Noordkade EZ Waddinxveen The Netherlands Phone: Fax: The conditions of your use and application of our products, technical assistance and information (whether verbal, written or by way of product evaluations), including any suggested formulations and recommendations, are beyond our control. Therefore, it is imperative that you test our products, technical assistance and information to determine to your own satisfaction whether they are suitable for your intended uses and applications. uch testing has not necessarily been done by King Industries, Inc. ( King ). The facts, recommendations and suggestions herein stated are believed to be reliable; however, no guaranty or warranty of their accuracy is made. EXCEPT A TATED, THERE ARE NO WARRANTIE, EXPRE OR IMPLIED, OF MERCHANTABILITY, FITNE OR OTHERWIE. KING HALL NOT BE HELD LIABLE FOR PECIAL, INCIDENTAL, CONEQUENTIAL OR EXEMPLARY DAMAGE. Any statement inconsistent herewith is not authorized and shall not bind King. Nothing herein shall be construed as a recommendation to use any product(s) in conflict with patents covering any material or its use. No license is implied or granted under the claims of any patent. ales or use of all products are pursuant to tandard Terms and Conditions stated in King sales documents. 8