Chemical Foaming Alternatives to Azodicarbonamide 2
Foaming Agents What are they and how do you use them? CFA Endothermic & Exothermic Challenges - Regulatory and Technical Case Study: PP Foam Cellular Structure Worldwide Markets 3
Foaming Agent (Blowing Agent) Two technologies: A substance which is capable of producing a cellular structure via a foaming process in a variety of materials that undergo hardening or phase transition, such as polymers and plastics. Physical Blowing Agent (Gas Injection) Cellular structure created by injecting gas in a super critical state directly into the barrel through equipment modifications. For high and medium density foams, gases utilized are usually N 2 or CO 2. Chemical Blowing Agent (Chemical Foaming Agent, CFA) Cellular structure created by a chemical reaction and heat during the plasticating process. Gas generated is usually CO 2, N 2, or a combination for high-to-medium density foams. N 2 CO 2 or N 2 And/or CO 2 4
Why Use Foam? Reduces Cost Less Material Consumption Reduces Weight Eliminates Sink Marks Improved Printing on Flat Surfaces Improves Thermal Insulation Improves Sound Insulation Higher Production Efficiency Lower Processing Temperatures Faster Cycle Time Reduces Machine Energy 5
Why Use Chemical Foam? Reduces Cost Less Material Consumption Reduces Weight Eliminates Sink Marks Improved Printing on Flat Surfaces Improves Thermal Insulation Improves Sound Insulation Easily Scalable Stable and Repeatable Simple Process, Easy to Feed Easy Startup Cost Easy to use Additive No Modifications to Equipment Needed Feeders and extrusion dies optimized for foam are worthwhile upgrades Higher Production Efficiency Lower Processing Temperatures Faster Cycle Time Reduces Machine Energy 6
Expectations of Modern CFA Early CFA Technology: 400-500 micron cells were common and acceptable in commodity parts High gauge variability and process challenges Closed-and-Open cells ADC is most common worldwide; Challenges due to potential toxicity No longer acceptable for use in food packaging, children's products Modern CFA Technology: Zero Toxicity Process Friendly formulations Value Added formulas for easy processing Uniform cell structure = more consistent physical properties, better surfaces Customers seek 200 microns cells and below, more Closed- Cell content Fine Cell structure = better retention of physical properties like impact strength and elongation at break
Primary CFA Types Exothermic Azodicarbonamide (ADC) : Creates Nitrogen and Ammonia, generates heat upon decomposition. Typically best for PVC or ABS compounds. Heat up the System. Make Larger cells in Olefins, Styrenics, etc. Best suited for SFM or extruded plastic lumber. 50 years of use in rubber and plastics Slow gas diffusion rate - Positive for some applications and negative for others Rapid and Robust gas expansion N 2 is not as soluble in olefins and styrenes as CO 2 Endothermic Carbonate / Acid Blends (SAFOAM Endothermic) : Creates CO 2 and water, absorbs heat. Most are FDA, Cool the system, usually make the best structure (small plentiful cells, white). 30 Years of use in Thermoplastics Self Nucleating Rapid gas diffusion rate Faster crystallization times due to CO 2 being a plasticizer Slow, controlled gas release (less pressure) CO 2 is more soluble in the polymer melt than N 2 8
11 February 2015 Regulatory pressure on ADC per REACH Harmonized classification H 334 Respiratory Sensitivity in EU Under the REACH Regulation(1), azodicarbonamide (ADCA) was identified as a Substance of Very High Concern (SVHC) in December 2012 in a unanimous opinion of the Member State Committee of the European Chemicals Agency (ECHA) considering its hazard classification as a respiratory sensitizer and the view that there is evidence of probable serious effects to human health which give rise to an equivalent level of concern to those of carcinogenic, mutagenic and reprotoxic substances. (1) Regulation (EC) No 1907/2006 of the European Parliament and of the Council of 18.12.2006 concerning the Registration, Evaluation, Authorization and Restriction of Chemicals. 9
Challenges Compounding and processing temperatures: Typical ADC Activation of approx. 210 C to 220 C Typical Carbonate Activation of approx. 150 C to 180 C SAFOAM HT Activation of approx. 210 C Gas Volume: Robust gas evolution rate of ADC may be preferred in free-foaming applications; such as plastisols and post-foaming applications (soft mats). Developments are underway to optimize endothermic CFA for these applications but it is a myth. that there are no alternatives to ADC in thermoplastic foams. 10
Extrusion Case Study 4/10/15 Melt Temp at clamp 380 F (193 C) Melt Pressure: 1800 psi Polypropylene: Exxon PP4712E1, 2.8 MFI 1.25 single screw extruder, 30:1 L/D, 3:1 compression ratio. AZ-130 (ADC - exothermic) powder and Safoam HT (endothermic) powder were used Calcium carbonate particle size: 1 micron Extrusion profile: ZONE 1 ZONE 2 ZONE 3 ZONE 4 CLAMP HEAD DIE 400 F 460 F 370 F 370 F 340 F 345 F 350 F 11
SAMPLE CELL RANGE (MICRONS) NOMINAL SIZE (MICRONS) DENSITY (G/CC) DENSITY REDUCTION 0.5% AZ-130 40-540 305 0.800 11.5% 0.5% AZ-130 0.5% HT Melt Temp at clamp 380 F (193 C) Melt Pressure: 1800 psi SAMPLE CELL RANGE (MICRONS) NOMINAL SIZE (MICRONS) DENSITY (G/CC) DENSITY REDUCTION 0.5% HT 30-140 85 0.750 17.0% 12
SAMPLE CELL RANGE (MICRONS) NOMINAL SIZE (MICRONS) DENSITY (G/CC) DENSITY REDUCTION 0.5% AZ-130 + 0.5% CaCO 3 45-320 180 0.685 24.2% 0.5% AZ-130 + 0.5% CaCO 3 0.5% HT + 0.5% CaCO 3 Melt Temp at clamp 380 F (193 C) Melt Pressure: 1800 psi SAMPLE CELL RANGE (MICRONS) NOMINAL SIZE (MICRONS) DENSITY (G/CC) DENSITY REDUCTION 0.5% HT + 0.5% CaCO 3 35-130 75 0.685 24.2% 13
Why the difference? ADC HT (Endo) Head Pressure 1,800 1,800 psi Temperature 200 200 celsius Solubility 0.4 2.4 moles of gas / kg of polymer Average Particle Size 3.0 15.0 microns Average Cell Size 305 85 microns CO 2 has higher solubility than N 2 in Polypropylene at comparable temperature. It readily dissolves at lower pressure. Particle size of the CFA is generally regarded as a prime determinant of cell size. However solubility of the gas must be taken into account when predicting cell size in the finished part. 14
SAMPLE CELL RANGE (MICRONS) NOMINAL SIZE (MICRONS) DENSITY (G/CC) DENSITY REDUCTION 0.75% AZ-130 100-450 290 0.644 28.8% 0.75% AZ-130 0.75% HT Melt Temp at clamp 380 F (193 C) Melt Pressure: 1800 psi SAMPLE CELL RANGE (MICRONS) NOMINAL SIZE (MICRONS) DENSITY (G/CC) DENSITY REDUCTION 0.75% HT 35-180 90 0.529 41.5% 15
SAMPLE CELL RANGE (MICRONS) NOMINAL SIZE (MICRONS) DENSITY (G/CC) DENSITY REDUCTION 0.75% AZ-130 + 0.75% CaCO 3 125-620 345 0.418 53.8% 0.75% AZ-130 0.75% HT-P + + 0.75% CaCO 3 0.75% CaCO 3 Coalescence Melt Temp at clamp 380 F (193 C) Melt Pressure: 1800 psi SAMPLE CELL RANGE (MICRONS) NOMINAL SIZE (MICRONS) DENSITY (G/CC) DENSITY REDUCTION 0.75% HT + 0.75% CaCO 3 50-230 135 0.495 45.2% Here we may have reached the foamability limit of this particular PP. 16
Cell Collapse (Coalescence) Explained Nucleating agents are used to create a starting point from where a cell can form as gas comes out of solution. A closed-cell structure is crucial in sustaining mechanical properties. However, in ADC condition 4, poor solubility of the N 2 gas has led to cell coalescence creating a closed and open cell structure reducing mechanical properties. 17
SAMPLE CELL RANGE (MICRONS) NOMINAL SIZE (MICRONS) DENSITY (G/CC) DENSITY REDUCTION 1% HT 30-220 115 0.623 31.0% Endothermic foaming agents are self nucleating and self regulating 1% HT 18
Less is More SAMPLE CELL RANGE (MICRONS) NOMINAL SIZE (MICRONS) DENSITY (G/CC) DENSITY REDUCTION 0.75% HT 35-180 90 0.529 41.5% 0.75% HT 1% HT SAMPLE CELL RANGE (MICRONS) NOMINAL SIZE (MICRONS) DENSITY (G/CC) DENSITY REDUCTION 1% HT 30-220 115 0.623 31.0% 19
Endothermic CFA Foam Tips High molecular weight, branched, low MFI polymers: Good Temperature Control; especially from head, through die Cool post-head : melt pumps, screen changers, mixers anything post barrel head Reverse Temperature profile Good Process Pressure 1800 Psi / 125 bar Other tips L/D 24:1 minimum 30:1 or greater for better mixing time and gas dispersion Plug vents Short Land lengths tightly gapped in center of sheet 20
Endothermic Chemical Foam Facts Safe to use FDA/EU food safe additive for thermoplastics Safe to ship REACH compliant, not a SVHC Easy to process White pellets or powders No royalties Scalable CFA Suppliers Reedy Chemical Foam Clariant Masterbatches ID Additives United Color Corp Tramaco and others 21
Worldwide use of Endothermic Chemical Foam Profile extrusion: Plastic building products are affordable, durable, and safe. Chemical blowing agents are currently utilized in such applications as window profiles, trim molding, siding and decking. Straighter profiles, increased load-bearing strength and improved insulation accompany lighter weights and faster throughput. Chemical blowing agents have also been used as a special effect colorant for faux wood, as an alternative to lamination. 22
Worldwide use of Endothermic Chemical Foam XPS Nucleation (Extruded Polystyrene): Chemical blowing agents contribute to environmental responsibility by providing a means to food packaging manufacturers to reduce polymer use, energy and overall costs. As a nucleating agent for physical gas processes, chemical blowing agents have allowed significant reductions in the use of Hydrofluorocarbons (HFC). The ability of a CBA to create more closed cells results in greater retention of gasses limiting the escape into the atmosphere. 23
Worldwide use of Endothermic Chemical Foam PP hollow profile sheets (twin wall fluted sheet): Excellent chemical resistance for building applications Easy sealing for interlayer pads and food packaging applications Low thermal conductivity for food packaging applications Lower density. > 10% weight savings Improved superficial smoothness for advertising applications Improved impact strength for packaging and building applications Higher energy absorption for packaging and building applications 24
Worldwide use of Endothermic Chemical Foam Sub-Sea Pipe Coatings Mechanical protection Negative buoyancy Internal flow efficiency Thermal insulation 25
Trial Summary HT activates at 207 C AZO-130 activates at 222 C HT (endo) generated ½ the gas of ADC Same density with ½ the gas, because the CO 2 was fully solubilized Self-nucleating HT endo requires no CaCo 3. Although it does help to an extent. A smaller uniformly dispersed cell structure results in a better finished part. AZ-130 HT Endothermic CFA is a viable alternative to ADC in most applications but must be optimized. 26
Questions? Visit us on the Web! www.reedychemicalfoam.com 980-819-6930 27