chemical foaming alternatives toreedychemicalfoam.com › conferencepresentations › ...cell...

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)

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.

4

Two technologies:

Physical Blowing Agent

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 N2 or CO2.

N2 CO2or

(Gas Injection)

Chemical Blowing Agent

Cellular structure created by a chemical reaction and heat during the plasticating process.

(Chemical Foaming Agent, CFA)

Gas generated is usually CO2, N2, or a combination for high-to-medium density foams.

N2 CO2And/or

• Reduces CostLess Material Consumption

• Reduces Weight• Eliminates Sink Marks

Improved Printing on Flat Surfaces• Improves Thermal Insulation

• Improves Sound Insulation

• Higher Production EfficiencyLower Processing TemperaturesFaster Cycle TimeReduces Machine Energy

Why Use Foam?

5

Why Use Chemical Foam?• Easily Scalable

Stable and RepeatableSimple Process, Easy to Feed

• Easy Startup CostEasy to use AdditiveNo Modifications to Equipment NeededFeeders and extrusion dies optimized for foam are worthwhile upgrades

6

• Reduces CostLess Material Consumption

• Reduces Weight• Eliminates Sink Marks

Improved Printing on Flat Surfaces• Improves Thermal Insulation

• Improves Sound Insulation

• Higher Production EfficiencyLower Processing TemperaturesFaster Cycle TimeReduces Machine Energy

Expectations of Modern CFAEarly 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 TypesExothermic

Azodicarbonamide (ADC) : Creates Nitrogen and Ammonia, generates heat upon decomposition.

• 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• N2 is not as soluble in olefins and styrenes as CO2

EndothermicCarbonate / Acid Blends (SAFOAM® Endothermic) : Creates CO2 and water, absorbs heat.

• 30 Years of use in Thermoplastics• Self Nucleating• Rapid gas diffusion rate – Faster crystallization times

due to CO2 being a plasticizer• Slow, controlled gas release (less pressure)• CO2 is more soluble in the polymer melt than N2

Most are FDA, Cool the system, usually make the best structure (small plentiful cells, white).

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.

8

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.

11 February 2015

Harmonized classification H 334 “Respiratory Sensitivity” in EU

Regulatory pressure on ADC per REACH

9

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

that there are no alternatives to ADC in thermoplastic foams.but it is a myth….

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

Challenges

10

ZONE 1 ZONE 2 ZONE 3 ZONE 4 CLAMP HEAD DIE400°F 460°F 370°F 370°F 340°F 345°F 350°F

Extrusion profile:

Polypropylene: Exxon PP4712E1, 2.8 MFI1.25” 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 Case Study 4/10/15

Melt Temp at clamp 380°F (193°C)Melt Pressure:1800 psi

11

SAMPLE CELL RANGE (MICRONS) NOMINAL SIZE (MICRONS) DENSITY (G/CC) DENSITY REDUCTION

0.5% HT 30-140 85 0.750 17.0%


0.5% AZ-130 40-540 305 0.800 11.5%

0.5% AZ-130 0.5% HT


12


0.5% HT + 0.5% CaCO3

35-130 75 0.685 24.2%


0.5% AZ-130 + 0.5% CaCO3

45-320 180 0.685 24.2%

0.5% AZ-130 + 0.5% CaCO3

0.5% HT + 0.5% CaCO3


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 polymerAverage Particle Size 3.0 15.0 microns

Average Cell Size 305 85 microns

CO2 has higher solubility than N2in 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

Sheet1

ADCHT (Endo)

Head Pressure1,8001,800psi

Temperature200200celsius

Solubility0.42.4moles of gas / kg of polymer

Solubility14.044.0grams per ml

Average Particle Size3.015.0microns

Average Cell Size30585microns

Sheet2

Sheet3


0.75% HT 35-180 90 0.529 41.5%


0.75% AZ-130 100-450 290 0.644 28.8%

0.75% AZ-130 0.75% HT


15


0.75% HT + 0.75% CaCO3

50-230 135 0.495 45.2%


0.75% AZ-130 + 0.75% CaCO3

125-620 345 0.418 53.8%

0.75% AZ-130 + 0.75% CaCO3

0.75% HT-P + 0.75% CaCO3

Coalescence


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 N2 gas has led to cell coalescence creating a closed and open cell structure reducing mechanical properties.

17


1% HT 30-220 115 0.623 31.0%

1% HTEndothermic

foaming agents are self nucleating and

self regulating

18


1% HT 30-220 115 0.623 31.0%


0.75% HT 35-180 90 0.529 41.5%

Less is More

1% HT0.75% HT

19

• 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 CFA Foam Tips

21

Endothermic Chemical Foam Facts

• Safe to useFDA/EU food safe additive for thermoplastics

• Safe to shipREACH compliant, not a SVHC

• Easy to processWhite pellets or powdersNo royaltiesScalable

CFA Suppliers

• Reedy Chemical Foam• Clariant Masterbatches• ID Additives• United Color Corp• Tramaco• and others

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.

Worldwide use of Endothermic Chemical Foam

22

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

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

•Internal flow efficiency•Thermal insulation

•Mechanical protection•Negative buoyancy

Sub-Sea Pipe Coatings


25

AZ-130

HT

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

CO2 was fully solubilized

• Self-nucleating HT endo requires no CaCo3.

Although it does help to an extent.

• A smaller uniformly dispersed cell structure

results in a better finished part.

Endothermic CFA is a viable alternative to ADC in most applications but must be optimized.

26

Questions? Visit us on the Web!

www.ReedyChemicalFoam.com980-819-6930

27

Slide Number 1Slide Number 2Slide Number 3Slide Number 4Slide Number 5Slide Number 6Expectations of Modern CFASlide Number 8Slide Number 9Slide Number 10Slide Number 11Slide Number 12Slide Number 13Slide Number 14Slide Number 15Slide Number 16Slide Number 17Slide Number 18Slide Number 19Slide Number 20Slide Number 21Slide Number 22Slide Number 23Slide Number 24Slide Number 25Slide Number 26Slide Number 27

chemical foaming alternatives toreedychemicalfoam.com › conferencepresentations › ...cell...

Documents