The Next Generation ofPolyphthalamide

High-performance Polyamides.

For years and to an increasing ex-

tent, plastics have been replacing

diecast metal parts. Structural

and functional parts for many

applications can now be pro-

duced from polyphthalamide

(PPA). These can be found under

the hood in automobiles, in hot

water applications in the sanitary

field as well as in industrial ap-

plications, e.g. for coffee ma-

chines. An advanced grade of this

high-performance polyamide is

characterized by its extremely low

moisture uptake.A polyphthalamide with extremely low moisture uptake is particularly well-suited for

production of connectors in the electronics sector

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V

Kunststoffe international 8/2008

MICHAEL KAISSER

T he polyphthalamide Grivory HT ischaracterized by high rigidity andstrength at temperatures up to

150°C. It is very resistant to chemicalsand exhibits minimal change in physicalproperties after moisture uptake.Grivory HT3 is an even more advancedPPA whose moisture uptake has beenminimized. This is important in the elec-trical and electronic fields when com-ponents undergo lead-free reflow sol-dering and functional parts must haveextremely good dimensional stability

(Title photo). In addition, Grivory HT3is an extremely hydrolysis-resistant andtough material. During its development,Ems-Grivory also displayed its concernfor the environment. Grivory HT3 isproduced largely from renewable re-sources.

Wide Range of Applications

As a materials group, polyphthala-mides have been known for a longtime and have been successful replace-ments for metal in numerous applica-tions in almost all branches of industry.Typical representatives from Ems-Grivory include Grivory HT1 (PA6T/6I)and Grivory HT2 (PA6T/66). These areused when economical alternativesto diecast metals such as zinc, aluminumor brass are required. Technical injec-tion molded parts made from thesePPA products distinguish themselvesthrough dimensional stability – even athigh working temperatures of upto150°C.

! PE104325

Ems-Chemie AGBusiness Unit Ems-GrivoryCH-7013 Domat/EmsSwitzerland Tel. +41/81/6 32-6922www.emsgrivory.com

Manufactureri

Translated from Kunststoffe 8/2008, pp. 111–113

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COMPOUNDS■

Grivory HT3 is a completely new PPApolymer that is based on long-chain di-amines. It exhibits important character-istics which are further improved com-pared to those of Grivory HT1 and HT2.These give it access to fields of applica-tion from which polyphthalamides haveso far been excluded.

Reduced Moisture Uptake

Until now, polyamides were limited bythe fact that moisture uptake seriously af-fected material properties.While it is truethat moisture uptake made themtougher, stiffness and strength were sig-nificantly reduced. By their nature,

polyphthalamides also absorb moisture,but to a much lesser degree and muchmore slowly. In the case of Grivory HT3,it has been possible to markedly reducemoisture uptake to 50% of that ofGrivory HT1. The consequence is thatthe new material exhibits exceptional di-mensional stability and very little ten-dency to creep. Its physical properties areessentially unaffected by moisture in thesurroundings.

The long-chain diamines in the poly-mer chain provide increased hydrolysisresistance. This is clearly demonstrated bythe extended half-value time after storagein a water/glycol mixture at 135°C. Elon-gation at break and tensile stress at breakfor Grivory HT3 drop to half their initialvalues only after 1,800 h (elongation atbreak) and 2,300 h (tensile stress atbreak). This corresponds to an increasein the half-value times of 80 and 50% overthose of the already hydrolysis-resistantGrivory HT1 GF50 grade (Fig. 1).

With its outstanding elongation andtoughness, Grivory HT3 contradicts theprevailing opinion that PPA may indeedbe very stiff but is also rather brittle. Even

when highly reinforced, Grivory HT3 is atough material with high elongation atbreak. As are all polyphthalamides, it isextremely chemical-resistant and it hasbeen possible to further improve the per-formance in hot oil (Fig. 2).

At Home in All Market Segments

Grivory HT is accepted in many applica-tions encountered in daily life and hasbeen recognized as a metal replacementfor years. It allows cost-effective produc-tion of lightweight parts that can with-stand high mechanical loads – a major re-quirement for automotive components.Its property profile is also appreciated in

this segment for other reasons. The verygood hydrolysis resistance and dimen-sional stability benefits components thatare in continuous contact with coolants.These include water pumps, radiator capsand expansion tanks. In combination

with exceptionally low permeation, thegood chemical resistance and high tough-ness predestine Grivory HT3 as a materi-al for highly stressed connectors in fluid-conducting systems (Fig. 3).

The electronics industry relies in-creasingly on miniaturization. Compo-nents are becoming smaller and smallerand more complex. At the same time, re-quirements regarding performance un-der extreme temperatures and repro-ducibility are becoming more demand-ing. Flame retardance is another essen-tial requirement. Grivory HT3 employsa halogen and phosphorus-free flame re-tardant that satisfies the WEEE andRoHS requirements. It also offers majorbenefits during the production processitself. The halogen and phosphor-freePPA products on the market to date havebeen extremely corrosive when it comesto barrels, screws and non-return valvesof injection molding machines. Accord-ingly, a great deal of attention was de-voted to this aspect during development.Grivory HT3 is significantly less corro-sive than previous halogen and phos-phorus-free flame-retardant polyph-thalamides on the market. This proper-ty in particular makes it a favorite in Asiafor the manufacture of connectors. Thefirst mobile phones with connectorsmade of Grivory HT3 are currently be-ing shipped.

As in the automotive industry, lowmoisture uptake and high dimensionalstability play an important role in theelectronics sector. Here, components areprocessed at high temperatures using theso-called reflow soldering process.A high

700 900 1,000 1,500

+50 %

+80 %

1,800 2,300

2,500

2,000

1,500

1,000

500

0

h

HT1 GF 50 HT1 GF 50more hydrolysis-resistant

HT3 GF50 H

Tim

e

Elongation at break [MPa]Tensile stress at break [MPa]

Hydrolysis ResistanceFig. 1. It has beenpossible to increasethe half-value timefor the mechanicalproperties of the ex-tremely low-moisturePPA Grivory HT3 byup to 80% comparedto hydrolysis-resist-ant Grivory HT1

© Kunststoffe

Hydrolysis-resistance

Chemicalresistance

Impactstrength

Notchedimpact strength

StiffnessElongation

Wateruptake

StrengthGrivory HT1Grivory HT3

Higher/better

Characteristics

Fig. 2. Grivory HT3distinguishes itselfas an optimum designmaterial above allthrough its low mois-ture uptake, excel-lent hydrolysis resist-ance and outstandingtoughness

© Kunststoffe

© Carl Hanser Verlag, Munich Kunststoffe international 8/2008

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moisture uptake would result in consid-erable blistering due to outgassing at tem-peratures of up to 260°C. Use of reflowsoldering is much simpler when GrivoryHT3 is involved. It is even possible to at-tain the highest and very important clas-sification, JEDEC class 1, for applicationsin this sector (Fig. 4).

Grivory HT is suitable for a wide rangeof applications in industry and the con-sumer area. Thanks to its significantly im-proved hydrolysis resistance, GrivoryHT3 can be used wherever high temper-atures and direct contact with water oc-cur. For instance, it can replace diecastfunctional components in coffee ma-chines, because the material can with-stand high pressures and temperatures,and survive the specified number ofbrewing cycles. Thanks to it high-tem-

perature capabilities and good resistanceto water, this poses no problems forGrivory HT3. Product approvals for di-rect contact with foodstuffs (EU, FDA,NSF 51) and drinking water (KTW,W270, ACS, WRAS, NSF 61) are ab-solutely essential in this regard.

Simple Processing

The Grivory HT3 grade of PPA has amelting point of 295°C, which is belowthat of Grivory HT1 (325°C) and HT2(310°C). This lower melting pointwidens the processing window, so thatthe injection molder can operate withina wide range of process temperatures.The recommended stock temperatureranges from 305 to 330°C, with lowertemperatures used for unreinforced

grades of Grivory HT3 and higher tem-peratures for reinforced grades. Themold temperature is another importantprocess parameter. The correct moldtemperature is a prerequisite for pro-duction of high-quality injection mold-ed parts with minimal warpage, low in-ternal stresses and tight dimensional tol-erance. The recommended mold tem-perature for Grivory HT3 lies between115 and 140°C, so that it is possible toused pressurized water equipment formold temperature control.

Many Different Grades

Grivory HT3 is available in heat-stabi-lized as well as unreinforced and rein-forced (30 to 50% glass fiber reinforce-ment) grades.For applications in the elec-trical and electronic sectors, glass fiber-reinforced, halogen and phosphorus-freeflame-retardant products with greatly re-duced corrosiveness are available. Thematerial is also approved for applicationsinvolving direct contact with foodstuffsand drinking water.

Conserving Resources

Grivory HT3 is based to a large extent ona raw material that is extracted from thecastor bean plant (Rhizinus communis),a natural and renewable resource.As a re-sult, after use, only the amount of CO2 isreleased that the castor bean plant itselfextracted from the atmosphere during itsgrowth. Grivory HT3 thus represents thefirst commercially available polyphthal-amide that is based verifiably on a re-newable resource. ■

THE AUTHORDIPL.-ING. (FH) MICHAEL KAISSER, born in 1970,

works in the automotive applications developmentdepartment at Ems-Grivory, Domat/Ems, Switzerland;michael.kaisser@emsgrivory.com

Fig. 3. The outstand-ing toughness and

good permeationcharacteristics pre-destine Grivory HT3

as a material for con-nectors in fuel lines

for automobiles

Fig. 4. After reflowsoldering, Grivory

HT3 exhibits no signsof blistering; compo-

nents achieve thehighest JEDECclassification

(JEDEC class 1)

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Kunststoffe international 8/2008

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