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Successfully Processing High Temperature Thermoplastics

Jim KostakesEntec PolymersAugust 13, 2015

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What Are High Temperature Thermoplastics?

These are thermoplastics that can be used in applications that require elevated temperature performance.

However, for the purpose of our discussion these are thermoplastics that require high melt temperatures and/or high mold temperatures.

These temperatures are generally higher than what is required to process commodity and/or engineering thermoplastics. Melt temperatures 275 400C (527 752F) Mold temperatures 120 - 200C (248 392F)

These materials generally also require higher drying temperatures. Drying temperatures 130 - 170C (266 - 338F)

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High Temperature Thermoplastics

Examples of High Temperature Thermoplastics include: Polysulfone (PSU) Polyethersulfone (PES) Polyphenylsulfone (PPSU) Polyphthalamide (PPA) Polyphenylene Sulfide (PPS) Liquid Crystal Polymers (LCP) Polyetherimide (PEI)* Polyetheretherketone (PEEK)*

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* NOTE: Entec Polymers does NOT sell PEI or PEEK

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Thermoplastic PyramidPage 4

AMORPHOUS SEMI-CRYSTALLINE

PAIPEEK

LCP

PET

PA6/66

PPA

PC

PPS

PBTPPOm

LDPE

PSU

POM

PP

HDPE

PMMA

SANPVC

ABS

PS

PPSU

SPS

PES

We are mainly concerned with these materials in this presentation.

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Processing Considerations

Drying: All of these high temperature thermoplastics

require drying prior to processing. The primary difference between drying high

temperature thermoplastics and commodity / engineering resins is the higher drying temperature and drying time.

Depending on the resin, drying temperatures of 130 170C (266 338F) are required.

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Melt Temperature: These high temperature thermoplastics require high

melt temperatures (270 - 400C). Heater bands need to be able to supply enough heat so

it is recommended to use ceramic heater bands with 5-8 W/cm2 of heating power.

Melt temperature is the actual temperature of the polymer, not just the barrel temperature set-points.

Care should be taken to avoid excessive temperatures or residence times as these can cause degradation products to form. Some of these products may be corrosive or odorous, for example with PPS.

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Gates and Runners: All standard gates and runners can be used with

high temperature thermoplastics. High viscosity thermoplastics like PSU, PES,

PPSU and PEI may require larger gates and runners.

Higher flowing thermoplastics like PPS and LCP can use smaller gates and runners.

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Processing ConsiderationsMold Temperature Because of the high mold temperatures used (120 - 200C /

248 392F) Molds should be made of high quality steel. Hot work tools steels

(AISI H10 to H13) have been successfully used with some high temperature thermoplastics.

Molds should be well insulated from the machine platens to minimize heat loss.

Hot oil or pressurized water is preferred over cartridge heaters for more uniform heating.

Mold temperature should be the actual steel temperature, not the mold temperature set-points.

Too cold of a mold temperature can result in excessive molded in stress which can lead to premature part failure.

Too cold of a mold temperature can result in incomplete crystallization (i.e. PPS) which can cause dimensional and warpage issues as well as inferior mechanical properties.

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Mold Temperature Typically the mold is closed and allowed to normalize

at it comes up to heat. Once the molding process is started, the actual steel

temperature should be checked. Checking again when in normal production is prudent.

The actual mold temperature can shift so temperature set points may have to be adjusted.

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Purging (start up): In most cases, purging with low melt index PE or PP or

purging compounds is acceptable. The purge compound should be run through the barrel

at about 250C (or at the melt temperature of the high temperature thermoplastic) until the barrel is cleaned.

Then the barrel temperatures may be increased to the desired temperature setting appropriate for the high temperature thermoplastic.

The high temperature thermoplastic material should be purged through the barrel before molding parts to ensure that all traces of purge compound are removed.

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Purging (shut down): Empty the barrel of all of the high temperature

thermoplastic. Introduce the purge compound and purge until

all traces of the high temperature thermoplastic material are gone.

The machine can now be shut down.

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Processing ConditionsPage 12

PRODUCTMELT

TEMPERATURE, CMOLD

TEMPERATURE, C DRYING, CUltrason S PSU (unfilled) 330 - 390 120 - 160 130 - 150Ultrason S PSU (reinforced) 350 - 390 130 - 180 130 - 150Ultrason E PES (unfilled) 340 - 390 140 - 180 130 - 150Ultrason E PES (reinforced) 350 - 390 150 - 190 130 - 150Ultrason P PPSU (unfilled) 350 - 390 140 - 180 130 - 150

Grivory HT1 PPA (reinforced) 330 - 350 140 - 160 80Grivory HT2 PPA (reinforced) 310 - 340 100 - 140 80

Fortron PPS (reinforced) 315 - 340 135 - 165 120 - 130

Vectra "A & B" LCP (reinforced) 285 - 295 80 - 120 150Vectra "C" LCP (reinforced 320 - 340 80 - 120 150Vectra "Ei" LCP (reinforced 335 - 345 80 - 120 150 - 170

Sheet1

PRODUCTMELT TEMPERATURE, CMOLD TEMPERATURE, CDRYING, C

Ultrason S PSU (unfilled)330 - 390120 - 160130 - 150

Ultrason S PSU (reinforced)350 - 390130 - 180130 - 150

Ultrason E PES (unfilled)340 - 390140 - 180130 - 150

Ultrason E PES (reinforced)350 - 390150 - 190130 - 150

Ultrason P PPSU (unfilled)350 - 390140 - 180130 - 150

Grivory HT1 PPA (reinforced)330 - 350140 - 16080

Grivory HT2 PPA (reinforced)310 - 340100 - 14080

Fortron PPS (reinforced)315 - 340135 - 165120 - 130

Vectra "A & B" LCP (reinforced)285 - 29580 - 120150

Vectra "C" LCP (reinforced320 - 34080 - 120150

Vectra "Ei" LCP (reinforced335 - 34580 - 120150 - 170

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Case Study: Isoplast RTPU

Isoplast is a rigid thermoplastic polyurethane (RTPU) produced by Lubrizol.

While not a high temperature thermoplastic, Isoplast is a very finicky material to process and therefore makes for a good example.

Isoplast MUST be processed exactly within the recommended processing conditions.

You cannot cheat with Isoplast like you can with some other thermoplastics.

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Isoplast is a live polymer. This means that is undergoes a rapid and reversible depolymerizationand repolymerization during processing.

This results in a very low molecular weight during processing (depolymerization) and a rebuilding of high molecular weight during cooling/solidification (repolymerization).

If not dried and processed within the recommended processing conditions the repolymerization does not place, resulting in a brittle, low molecular weight polymer.

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Isoplast RTPU

2015-M-3A

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Case Study: ISOPLAST Rigid TPU

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Processing variables that affect Isoplast are: Drying Melt temperature Mold temperature Shear / Injection Speed Packing Cavity Balance

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DRYING: Because Isoplast is susceptible to hydrolysis it

MUST be dried properly. Drying temperature is within 10F of the glass

transition temperature (varies with the grade). Moisture content should be 0.02% or less. Drying time of 12 hours minimum, even from

sealed bags. Even 15 minutes exposure to ambient

conditions can absorb moisture and cause splay.

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Case Study: Isoplast RTPUMELT TEMPERATURE: Melt temperature range is 220 260C,

depending on the grade. Melt temperature should be closely

controlled since Isoplast has a very steep viscosity temperature curve.

Hot runners are OK but need tight temperature control. Manifold should have at least one temperature control zone.

Each hot drop should have individual temperature control.

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Case Study: Isoplast RTPUMOLD TEMPERATURE: Mold temperature is critical for the

repolymerization to take place. Mold temperature range is 65 - 120C,

depending on the grade. Mold temperature MUST be a minimum of

65C but will vary with the grade. Mold temperatures below the minimum

temperature will produce parts that are brittle and may have poor surface aesthetics.

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Case Study: Isoplast RTPUOTHER PROCESSING CONDITIONS: Isoplast does not like high shear conditions

so the injection speed should be slow and the gates and runners should be large. Minimum gate size of 0.035-inches Sub-gates are not recommended Splay is a sign of over-shearing

Isoplast does not like to be over-packed. Over-packing (or cavity imbalance) should be avoided otherwise the parts will be brittle and require annealing.

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Case Study: Isoplast RTPUPage 21

PRODUCTMELT

TEMPERATURE, CMOLD

TEMPERATURE, C DRYING, CIsoplast 101 low heat 220 - 240 65 - 80 85 - 90Isoplst 202EZ high heat 240 - 260 75 - 120 125 - 140Isoplast 101LGF40 low heat long glass reinforced 240 - 260 65 - 90 80 - 100Isoplast 202LGF40 high heat long glass reinforced 240 - 260 95 - 120 125 - 140

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Isoplast RTPU

Isoplast is shear sensitive. Slow injection speeds with little or no

back pressure 200 psi max Slow screw recovery speed Screw and check ring need to be tight Independent heat on nozzle tip

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Isoplast RTPU

If possible use a return air cooler at the drier Better dryer efficiency The air cooler can trap low melting point

volatiles and plasticizers which could damage the molecular sieve material in the desiccant beds.

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Summary

High heat thermoplastics have continuous use temperature ratings of 150C+

Running hot molds is essential to insure low to no molded-in stress

Molds need to be insulated from the plattens Mold and material melt temperatures should be

checked with a pyrometer Dont rely on temperature set-points

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Thank you.

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Successfully Processing High Temperature ThermoplasticsWhat Are High Temperature Thermoplastics?High Temperature ThermoplasticsThermoplastic PyramidProcessing ConsiderationsProcessing ConsiderationsProcessing ConsiderationsProcessing ConsiderationsProcessing ConsiderationsProcessing ConsiderationsProcessing ConsiderationsProcessing ConditionsCase Study: Isoplast RTPUCase Study: Isoplast RTPUIsoplast RTPUCase Study: Isoplast RTPUCase Study: Isoplast RTPUCase Study: Isoplast RTPUCase Study: Isoplast RTPUCase Study: Isoplast RTPUCase Study: Isoplast RTPUIsoplast RTPUIsoplast RTPUSummarySlide Number 25

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Successfully Processing High Temperature …socalspe.org/assets/successfully-processing-high-temperature...Successfully Processing High Temperature Thermoplastics. Jim Kostakes