Acid & Blocked Acid Catalysts

Transcription

1 & & Blocked Catalysts & ACID & BLOCKED ACID CATALYSTS Why Use Catalysts? Today s need for high solids and waterborne coatings requires greater use of high reactivity, low viscosity resins and crosslinkers. Conversion of these systems into tough, chemically resistant, high performance coatings at reduced cure temperatures can be accomplished with the use of a catalyst. Acrylics, alkyds, epoxies and polyesters with reactive functional groups, such as hydroxyl carbamate, siloxane or amide can be reacted with melamine, urea and benzoguanamine crosslinkers. The proper use of catalysts can facilitate the crosslinking reaction resulting in the following benefits: ECAT Energy Required With Catalyst Shorter cure schedules Lower cure temperatures for thermoset high solids and waterborne coatings Energy savings E Energy Required Without Catalyst Improved hardness, gloss, humidity and corrosion resistance Improved mechanical properties King Industries continues to develop catalysts to meet the ever expanding needs of a rapidly changing market. Free Or Latent Catalyst? While acid catalysts provide the fastest cure and lower curing temperatures, blocked or latent catalysts are typically chosen for systems requiring greater package stability. In addition, troublesome catalyst-pigment interaction can be reduced or eliminated with the use of blocked catalysts. As can be seen in the table which follows, King s catalyst line is based upon a variety of acids. The middle column denotes the free acid versions while the far right column shows amine blocked or covalently bonded derivatives for applications requiring extended package stability. HO3S H 19C 9 Type Dinonylnaphthalene Disulfonic Catalyst By Type C 9H 19 SO3H Dinonylnaphthalene Sulfonic H 19C 9 Dodecylbenzene Sulfonic SO3H p-toluene Sulfonic CH3 C 12H 25 SO3H C 9H 19 SO3H Phosphates AAP/PAP Alkyl Phosphates Phenyl Phosphates Other & Mixed s Catalysts Blocked Catalysts W XC B 8924 XC-194K

2 Product Offerings The chemical structure of the catalyst, as well as the quantity used, can have a profound impact on film properties such as adhesion, corrosion resistance, flexibility and impact resistance. These observations are apparent not only among varying acid types but also among different products within the same chemical family. The type of crosslinker used will also affect the choice of catalyst. High solids and waterborne coatings are typically formulated with monomeric crosslinkers such as hexa(methoxymethyl)melamine (HMMM) or mixed ether melamine; reaction of these crosslinkers with hydroxy or carbamate functional groups is best achieved with strong acid catalysts like or. More reactive crosslinkers, which are more polymeric but contain high levels of -NH groups, respond better to a weaker acid such as acid phosphates or low dosages of amine blocked sulfonic acids. The table to the right, matches the type of crosslinking agent and the acid catalyst most suitable for each class. King offers a broad selection of catalysts to satisfy Cure Time, Minutes Crosslinking Agent Fully alkylated monomeric M/F resins: Fully methylated Fully butylated Mixed ethers Urea formaldehyde resins Benzoguanamine resins Glycoluril resins Highly alkylated, high imino M/F resins Partially alkylated polymeric M/F resins General Category Strong s pka<1 Weak s pka 1-3 Types P-TSA Phosphates Metal Salts Carboxylic RELATIVE ACID STRENGTH: >>>>Phosphates>Carboxylates almost every possible curing parameter. Relative cure profiles for Blocked Catalysts are shown below. Relative Cure Profiles for Blocked Catalysts for Amino Crosslinked Systems N- N-8924 N-2530 N-2558 N-2107 N-2547 N-3327 N-5225 N- N-5528 N-5925 N-4575 N-5414 N-4167 N-1419 N-1323 N-1953 Coil conditions up to 220C N-1323, N-1953, N-1419, N Cure Temperature, o C Cure Profiles - Blocked Catalysts & ACID & BLOCKED ACID CATALYSTS Pages 3 & 4

3 Catalyst Selection Chart by Application & ACID & BLOCKED ACID CATALYSTS PRODUCT SELECTION: The application charts that follow can be used to arrive at good starting point product recommendations based upon King s decades of experience in catalysis. However, we strongly recommend given the complexity of the selection process and the subtle nuances of each individual product that you take advantage of our Technical Service Department who will be more than happy to assist you. They can be quickly reached either by coatings@kingindustries.com or phone: (203) for assistance. KEY TO CATALYST TYPE - (PAGE #) 1419 Solubility 1051 Corrosion 1323 High Temperatures Primers & Metal Substrates 5076* 5925* Moisture Can (7) (8) & OTHER (9) (10 Topcoats Coil, Appliance General Industrial 2558 Blister & 1953 High Bake Systems 1419 Corrosion Moisture 2547 & & 2107 Textured Finish * Complaint FDA 21 CFR, Sec (b) (3) xii & Xiii (a&b)

4 Catalyst Selection Chart by Application Solubility & Primers & Solubility & Wood & Paper Substrates Automotive Topcoats: Basecoats & Clearcoats 5528 & 5225 Intercoat 5225 UV Durability 2547 Adhesives, Sealants B W 129B Plastics Adhesives, Sealants & Inks 1051 Moisture Inks & ACID & BLOCKED ACID CATALYSTS Moisture Moisture 1040W 1040W Pages 5 & 6

5 Catalysts & ACID & BLOCKED ACID CATALYSTS Advantages of Dinonylnaphthalene Disulfonic () catalysts include: Excellent adhesion properties Superior corrosion & moisture resistance Detergent resistance Excellent for solventborne and waterborne coatings ADHESION TESTS A polyester/hmmm general industrial enamel catalyzed with blocked catalyst demonstrates (in the chart below) its superior crosshatch adhesion performance compared to a blocked catalyst at a 150 C cure schedule. Enamels were applied to iron phosphated and untreated aluminum panels. Property Catalysts PRODUCT Blocked Catalysts 3327 Type Volatile Isobutanol Isopropanol N/A 107 C Isobutanol Isopropanol max 120 C Isobutanol Isopropanol N Cure Schedule: C % Active P-TSA (25%, Amine) Pencil Hardness H-2H 2-3H to Phosphated CRS 96% 24% # or ph lbs./gal. Property Gardner Color Minimum Cure* Isobutanol max. RT max 90 C Cure Schedule: C (Blocked Cat.) Pencil Hardness H-2H H-2H Pendulum Hardness to Untreated Aluminum * Cure Schedule: 30 minutes - Resin/Urea (60/40 ratio), ** PMT - Peak Metal Temperature The adhesion advantages of are also evident when compared to. A significant improvement was observed when crosshatch adhesion tests were conducted on untreated aluminum panels 90% 20% Attributes/Uses General purpose catalyst. Excellent water, detergent and salt spray resistance. Better solubility than other amine blocked DSA catalysts. Better solubility than, slower curing. Good salt spray resistance and adhesion. Best overall properties. Excellent water and corrosion resistance, and adhesion.

6 Catalysts to Telegraphing 0.32% 0.9% In the photographs above, resistance to telegraphing of surface imperfections over oily substrates is demonstrated. A skin cream containing oil was applied to the hand and imprinted onto the steel test panel prior to coating with a high solids acrylic enamel. catalysis improves wetting and reduces telegraphing of metal surface variations. PRODUCT 1051* Type Volatile % Active # or ph lbs./gal. 2-Butoxyethanol N/A 125 C * 1051 is an excellent catalyst for anodic acrylic electrocoating Catalysts based on Dinonylnaphthalene (Mono) Sulfonic () offer the following advantages: Hydrophobic catalyst Excellent corrosion resistance Overbake resistance Excellent resistance to telegraphing Excellent substrate wetting properties Help reduce conductivity in coating Excellent for primers and coil coating applications Gardner Color Minimum* Cure Xylene N/A 150 C Xylene/MIBK 30 N/A 7.74 N/A 150 C Butanol 2-Butoxyethanol Both and Catalysts offer superior corrosion resistance over other acid types such as as shown to the right. Photos of 300 hours salt spray N/A 150 C Blocked Blocked Catalyst Attributes/Uses Best water and corrosion resistance. Recommended for high temperature applications on metal. Blocked Catalysts High temperature applications. Excellent solubility in aromatic and aliphatic solvents. Electrostatic spray. High bake applications for water, detergent and salt spray resistance. Resolves solvent popping in thick films. Excellent humidity and detergent resistance. & ACID & BLOCKED ACID CATALYSTS 1953 Butanol 2-Butoxyethanol N/A 150 C High bake amino crosslinked systems such as coil coatings and metal decorating. * Cure Schedule: 30 minutes - Resin/Urea (60/40 ratio) Pages 7 & 8

7 Catalysts & Other Blocked Catalysts & ACID & BLOCKED ACID CATALYSTS Some of the key benefits of using Dodecylbenzene Sulfonic () catalysts include: Broad solubility High gloss UV resistance Excellent compatibility in high solids and waterborne coatings Excellent for automotive basecoats and topcoats Additionally select catalysts comply with FDA 21 CFR, Sec (b) (3) xii & xiii (a&b) and EC Directive 10/2011 as shown below. XC-194K and 8924 are newer blocked acid catalysts designed for specific performance criteria. XC-194K is for primers containing anti-corrosive pigments and 8924 is for fast cure and stability in waterborne formulations. Catalyst PRODUCT Type Volatile % Active # or ph lbs./gal. Gardner Color Minimum Cure* Isopropanol RT Blocked Catalysts Isopropanol C Xylene 25 N/A C Isopropanol C Isopropanol C Other Blocked Catalysts XC-194K 8924 OTHER Hydrocarbons Ester Solvents CORROSION RESISTANCE XC-194K Coil Primer 500 Hours Salt Fog Exposure Cure Schedule: C 235 C max 140 C PMT** OTHER Water RT Control: Loss of coating in scribe area and #6-7 medium blisters on 70-80% of the surface. XC-194K: No loss of coating in scribe area after 500 hours salt spray. Attributes/Uses Complies with FDA 21 CFR, Sec (b) (3) xii & xiii (a&b) and EC Directive 10/2011. Best solubility in high solids enamels. Good solubility in aliphatic solvents. Excellent electrostatic spray (nonaqueous). Good intercoat adhesion. Blister resistant. Broad solubility. Excellent color stability. Complies with FDA 21 CFR, Sec (b) (3) xii & xiii (a&b) Amino crosslinked primers containing basic or ion exchange type anticorrosive pigments Balance of rapid cure/stability in waterborne formulations. * Cure Schedule: 30 minutes - Resin/Urea (60/40 ratio), **PMT - Peak Metal Temperature

8 /Mixed Catalysts Pendulum, cycles and Mixed Catalysts PRODUCT W 129B Type Volatile % Active # or ph lbs./gal. Catalysts based on para-toluene Sulfonic () or alkane sulfonic acid blends offer the following benefits: Gardner Color Fastest cure response Low temperature cure Excellent UV resistance Excellent gloss For solventborne and waterborne coatings Minimum Cure* Isopropanol RT Water RT Mixed s Methanol/n-Butanol RT and Mixed - Blocked Catalysts F 225 F 250 F Isopropanol C Isopropanol C TSA Methanol Isopropanol Methanol Isopropanol C C Water C P-TSA Ethylene Glycol C The graph to the left demonstrates the low temperature cure capabilities of a blocked catalyst as measured by pendulum hardness. The coating is a high solids polyester/hmmm clearcoat formulation that was baked at three different temperatures for 15 minutes. Superior hardness develops at F bakes when the catalyst is used. Attributes/Uses Highest gloss. Fast cure. Excellent weathering and exterior durability. As above, non-flammable for waterborne applications. Fastest cure. Wood and paper coatings. Good metal mark resistance. Fast cure. Low temperature cure. Excellent stability. Slightly higher resistivity than. Better ketone solubility. Low temperature cure. Low tendency to yellow or wrinkle. Easy incorporation into aqueous systems Effective in controlling wrinkling, popping & blistering in HS systems & ACID & BLOCKED ACID CATALYSTS * Cure Schedule: 30 minutes - Resin/Urea (60/40 ratio) Pages 9 & 10

9 Phosphate Catalysts & ACID & BLOCKED ACID CATALYSTS Weak acid catalysts based on phosphate chemistries are recommended for: Partially alkylated, high imino and polymeric melamine crosslinkers Hybrids and carboxy-epoxy coatings Siloxane crosslinking They offer: Excellent gloss and chemical resistance Excellent adhesion properties The graph to the right compares the adhesion advantage that 4000 shows in comparison to two commercial phosphate catalysts when used to catalyze an acrylic/ polymeric melamine clearcoat. Phosphate Catalyst PRODUCT XC-235 Type Volatile Alkyl Phosphate Alkyl Phosphate Phosphate % Active Phosphate Blocked Catalysts W 4575 Phosphate Isopropanol Isobutanol Phosphate Water Isopropanol Phosphate Methanol Butanol # or ph lbs./gal. % Gardner Color Minimum Cure* C C C C C C % to Aluminum & Steel 0 Phos. A Phos.B N-4000 Aluminum Steel Attributes/Uses Broad solubility and excellent adhesion, Good package stability. Excellent adhesion. Siloxane Crosslinking. Recommended with high imino and partially alkylated melamine type crosslinkers Blocked phosphate for high NH/polymeric melamines. Siloxane crosslinking. Aqueous systems using high NH/polymeric melamines. High gloss. Superb storage stability with polymeric amino resins. * Cure Schedule: 30 minutes - Resin/Urea (60/40 ratio)

10 Formulating Information - Use Levels In general, the time and temperature conditions of cure will determine the correct catalyst for the application. Strong acids with typical pka strengths of approximately should give equivalent rates of cure at equal molar concentrations of the acid group. Blocked catalysts will demand higher temperatures for full activation, and the pka of the blocking agent attached to the acid will also influence the rate of reactivity. The two charts which follow provide general information on typical catalyst use levels by acid type based on a 30 minute cure schedule for a typical binder resin/hmmm ratio of 75/25. The percentage of catalyst shown is as supplied based on total resin solids. A ladder study of catalyst levels should be conducted to optimize the formulation. Do not over catalyze. Using too much catalyst can be a costly mistake and one that can cause film properties to suffer significantly. Catalyst Use Level, % by Weight Catalyst Use Level, % by Weight Catalysts - Typical Use Levels N-1051 () N- () K-1040 (ptsa) N-5076 () Cure Temperature, C Blocked Catalysts - Typical Use Levels Blocked Blocked or Blocked ptsa Cure Temperature, C & ACID & BLOCKED ACID CATALYSTS Pages 11 & 12

11 Catalyst Selection by Applications & Performance Application areas for acid and blocked acid catalysts cover a broad spectrum of end-uses, from medium to high solid solvent-based formulations to water reducible and latex systems. Typical applications are summarized below. The cross reference chart shows you specific performance properties to types of catalysts. As always, our technical service staff can assist you with meeting your particular requirements. Application Solvent Systems Systems Appliances 1323, 1419, 3483 Automotive Basecoat 5525, 5528, Automotive Topcoat/Clearcoat 5225,, 2522, 4054, 5414 & 5528 Can 5925, 3483, & 4046 Coil (PCM) 1051, , 2107 & 4046 Inks, Metal Decorating, B Paper Coatings 1040, 129B Primers, 1323 Wood Finishing, B Catalyst Selection by Performance Properties Performance Property,, , 5528, , 5528, 5225 and 4167, , W 1040W 1040W, 2530,, 1040W 2530 Chip Corrosion Detergent Electrostatic Conductivity FDA KEY: - Highly Recommended - Recommended AAP/PAP Film Flexibility Film Hardness Flow & Leveling & ACID & BLOCKED ACID CATALYSTS High Gloss Moisture QUV 8