Einsatz optimierter Glasfaser-verstärkter PP-Produkte ...amk/files/Mecklenburg_2003.pdf · Glass fiber reinforced PP products in principle can be developed / optimized with 2 different

Einsatz optimierter Glasfaser-verstärkter PP-Produkte,Ingenieurtechnische Zielstellungen und Anforderungen an

UL-Standards

Thomas Mecklenburg;

Basell Polyolefine GmbH, 65926 Frankfurt

Underwriters Laboratories (UL) ist in den USA die führende Organisation, die die Sicherheit von kommerziellen Elektrogeräten im Haushalt und Büro prüft und zertifiziert. Auch dafür eingesetzte sog. „recognized components“ wie Kunststoffe unterliegen der Überwachung durch UL.

Für Kunststoffmaterialien, die aufgrund der Anwendungen in Langzeitkontakt mit Heisswasser und Detergentien stehen (z.B. bei Waschmaschinen und Geschirrspülern)

wurden von UL Standards mit Langzeit-Detergentienprüfungen entwickelt, wobei die

mechanischen Kennwerte (Zugfestigkeiten, Schlagzähigkeiten) nach der Prüfung noch

mindestens 50% der Ausgangswerteaufweisen müssen.

Bild 1: US washing machine complying with UL 2157

Insbesondere für Glasfaser-verstärkte PP-Produkte ergibt sich aus den UL Standards eineSelektion in für Anwendungen mit Langzeit-Heisswasser- und Detergentien-Kontaktgeeignete (a) und weniger geeignete Produkte (b):a) Dabei zeigen geeignete Produkte, die oft nur mittlere Zugfestigkeiten und Schlag-

Zähigkeiten aufweisen, im Heisswasserkontakt einen relativ geringen prozentualen Abfallder mechanischen Kennwerte. Die UL-Anforderungen (UL 2157) z.B. für den Einsatz von Laugenbottichen von Waschmaschinen werden damit problemlos erfüllt.

b) Durch eine Optimierung des Kopplungs-Systems können die mechanischen Kennwerte von GF-verstärkten PP-Produkten um bis zu 40% gesteigert werden. In Kontakt mitHeisswasser ist jedoch teilweise ein prozentual deutlich stärkerer Abfall zu beobachten,was den Einsatz in UL geprüften Waschmaschinen und Geschirrspülern limitiert.

Diese Situation ist für die Konstruktion entsprechender Bauteile aus GF-verstärkten PP-Produkten unbefriedigend und definiert das Entwicklungsziel, die Heisswasser-Beständigkeitoptimierter, hochsteifer und schlagzäher Glasfaser-verstärkter PP-Produkte zu verbessern, um sicher den UL Anforderungen zu genügen. Nicht eindeutig identifiziert ist u.a. der mikros-kopische Mechanismus, der den steilen Abfalls insbesondere der Zähigkeit in teilweise nur 24h Heisswasserlagerung verursacht.

Dr.Thomas Mecklenburg Basell Polyolefine GmbH / FrankfurtJuni 2003

EEinsatzinsatz optimierteroptimierter

GlasfaserGlasfaser--verstärkter PPverstärkter PP--Produkte,Produkte,

ingenieurtechnische Zielstellungen undingenieurtechnische Zielstellungen und

Anforderungen an Anforderungen an ULUL--StandardsStandards

((UUnderwritersnderwriters LLaboratories)aboratories)

orHow UL affects

product development / optimization and business

Thomas Mecklenburg / 062003

Subject

Glass fiber reinforced PP products for electrical appliances

(for household and similar use) which comply with UL requirements

Example for applications of reinforced PP products:

Different washing machine constructions (tubs )


Content

• UL background and marks

• Qualifying end products and plastic materials at UL

• UL standards

• Requirements / test program for plastic materials

• Mineral filled PP products (immersion tests)

• Glass fiber reinforced PP products (typical properties / immersion)

• Application and development targets

• Glass fiber sizing and interphase

• Conclusion


UL’s (Underwriters Laboratories) Background

Independent, not for profit product-safety testing and

certification organization in the USA and a leading provider of

product conformity assessment in the world.

Established in 1894

In 2002:

• UL evaluated 106,942 products and 18,750 typs of products

• There were 64.000+ manufacturers producing UL certified products

• There are 127 UL inspection centers located in 65 countries, and inspecting UL

customers in 96 countries (555,222 follow-up visits at 5,414 registered facilities

on the world in 2002)

There are 886 UL Testing Standards covering a wide range of products


The UL Marks (for end products and recognized components)

• The UL mark on a product (End product or Components)

means that the complete product has been tested by UL and

meets UL safety requirements and then undergoes periodic

checks (Follow Up Services) to ensure it continues to comply

with UL requirements.

Typical certified products could be electrical appliances such

as white goods, small appliances, power tools etc. for household

and similar use.

• Plastic Materials are Recognized Components

• But the use of Recognized Components in an end product does

not mean the end product will be UL LISTED


Qualifying a new End Product at UL

For qualifying a new End Product where electrical, fire, or

mechanical hazards could be present UL judges the safety of the

product based on

– Construction: mechanical assembly, internal wiring, electrical and thermal insulation,

over-current protection, thermal cut-off, switches, grounding, etc.

– Performance: strength of enclosure, stability, leakage current, dielectric voltage-

withstand, abnormal operation, exposure to moisture, exposure to chemicals, flammability,

etc.

– Manufacturing and Production Tests

– Use and care and installation / Instruction Manuals.


Why UL listing of plastic materials ?

The UL listing of plastic materials as recognized

components including compliance with UL standards is

one of the major requirements from global End

Product (electrical appliances) producers.

The use of recognized plastic materials for

End Products helps reduce test work, time and

costs for the producers (customers of Basell).

The UL listing of plastic materials is a competitive

advantage.


Qualifying a new Plastic Material as

Recognized Component ( UL Standards )

• To qualify Plastic Materials as a Recognized Component the producer /

requestor submits materials to UL for testing under UL Standards

UL 94 Flammability (HB and V rating)

UL 746A Short Term Properties

Electrical and Ignition Properties, Mechanical Properties, Thermal

Properties, Dimensional Changes, Chemical Resistance,

Identification Testing ( IR, DSC, TGA )

UL 746B Long Term Heat Aging

RTI (Temperature / survive 100.000 hours without failure)

UL 746C Use in Electrical Equipment Evaluations

Special UL standards / requirements depending from the

application and use - Immersion testing for example(see list of Household and Similar Electrical Appliances)


UL Standards / End products must comply with

• UL 45 Portable Power Tools

• UL 82 Electric Gardening Appliances

• UL 197 Commercial Electric Cooking Appliances

• UL 268 Smoke detectors for Fire Protective Signaling Systems

• UL 416 Refrigerated Medical Equipment

• UL 484 Room Air Conditioners

• UL 497 A, B, C Protectors for Communication Circuits

• UL 499 Electrical Heating Appliances

• UL 507 Electric Fans

• UL 563 Ice Makers

• UL 696 Electric Toys

• UL 745-1 thru 37 Portable Electric Tools*@

• UL 826 Household Electric Clocks

• UL 859 Household Electrical Personal Grooming Appliances

• UL 867 Electrostatic Air Cleaners

• UL 875 Electric Dry Bath Heaters



• UL 923 Microwave Cooking Appliances

• UL 961 Electric Hobby and Sports Equipment

• UL 985 Household Fire Warning System Units

• UL 998 Humidifiers*

• UL 1017 Vacuum cleaners, Blower Cleaners*

• UL 1026 Electric Household Cooking and Food Appliances

• UL 1082 Household Electric Coffee Makers and Brewing Applic.

• UL 1086 Household Trash Compactors

• UL 1240 Electric Commercial Cloths-Drying Equipment

• UL 1431 Personal Hygiene and Health Care Appliances

• UL 1447 Electric Lawn Mowers

• UL 1448 Electric Hedge Trimmers

• UL 1459 Telephone Equipment

• UL 1647 Motor-Operated Massage and Exercise Machines

• UL 1727 Commercial Electric Personal Grooming Appliances



• UL 250/471 Household Commercial Refrigerators and Freezers*

• UL 2158 Electric Clothes Dryer*

• UL 749 Household Dishwashers*

• UL 2157 Electric Cloth Washing Machines and Extractors*

• 60335-1 Safety of Household and Similar Electrical Appliances

* UL/ Canadian Standards Association (CSA) Harmonized Standards

@ UL/International Electrotechnical Commission (IEC) Harmonized Standards


UL requirements on plastic materials (UL 2157 and 749)

Required test program for plastic materialsexposed to detergent and bleach solutions typically used in wash water tubs

and other fluid containing parts in laundry and dishwashing equipment.

Specimens in natural / unpigmented color are to be tested for

tensile strength

(in accordance with ASTM D 638, using Type I specimens) and

tensile impact energy(in accordance with ASTM D 1822, using Type S specimens).

Upon comparison to unconditioned specimens,

50% retention of properties is required for all

exposures.


Test program for plastic materials (UL 2157 and 749)

The conditions are as follows:

UL 2157 / Laundry Machine requirements1. for a part subjected to wash water, 30 specimens (10 for each period)

shall be immersed for 30, 60, and 138 days at 82°C in 2.5% (by weight),

aqueous laundry detergent solution

2 for a part subjected to laundry bleach, 10 specimens shall be immersed

for 1000 h at 100°C in 100% bleach; and

3. The laundry detergent and bleach solution shall consist of 50 g of non-concentrated

powdered laundry detergent and 100 ml of bleach per litre of water.

UL 749 / Dishwasher requirements

4. immersion of 10 specimens each for 30, 60, and 138 days at 82°C in 2.5%,

by mass, aqueous dishwasher detergent solution for a part subjected to wash

water; or

5. immersion of 10 specimens for 1000 h at 100°C in 100% rinse agent solution

for a part of a rinse agent dispenser.


Tensile properties of a mineral filled productover 138 days at 82°C (test conditions: UL 2157 / 749)

20% mineral filled heco product

for washing machine tubs and other white good interior parts

10

15

20

25

30

35

0 10 20 30 40 50 60 70 80 90 100 110 120 130 138

Immersion period (days)

Te

ns

ile

str

en

gth

(M

Pa

)


Impact strength of a mineral filled productover 138 days at 82°C (test conditions: UL 2157 / 749)

40% mineral filled PP homo product

for different white goods interior parts

0

1

2

3

4

5

6

0 10 20 30 40 50 60 70 80 90 100 110 120 130 138


No

tch

ed

Ch

arp

y i

mp

ac

t(2

3°C

) k

J/m

²


Mineral filled PP products for dish washer interior parts (UL 749)


Typical effects / properties for PP productsunder UL immersion conditions

• Mineral filled Hostacom* products based on PP Homopolymers

or Heco‘s comply with the UL standards 2157 and 749.

Mostly there is not a significant change of the tensile and

impact properties over the testing period, usually on a low level of

mechanical properties.

• But Glass fiber reinforced PP products (chemically coupled)

with a much higher level of mechanical performance often exhibit

a typical more or less rapid decrease of the tensile and impact

strength within only few days in aqueous laundry and dishwasher

detergent solutions but also in demineralized hot water.

* Hostacom = Tradename of Basell for compounded PP products


Notched Charpy impact strength (ISO 179/1eA) of different 30% Glass fiber reinforced Hostacom products over 30 days hot water immersion

Typical decrease of the impact strength

of different commercial Hostacom products

(30% GF reinforced) / hot water (demin. Water at 95°C)

2

4

6

8

10

12

14

0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30


Notc

hed

Char

py

impac

t (2

3°C

) kJ

/m²

UL 2157 approved


Front loading washing machine tub made of a glass fiber reinforced Hostacom grade (UL 2157)


US / European washing machine which comply with UL 2157


GF reinforced PP productsApplication and development targets

Glass fiber reinforced PP products in principle can be

developed / optimized with 2 different targets:

Comply with the UL standards 2157 and 749 with an only

slight relative decrease of the tensile and impact strength over

138 days immersion.Example: 30% glass fiber reinforced homo PP product:

Tensile strength at break (ISO 527-2): initial value in the range of 70 - 80 MPa.

Unnotched Charpy impact strength (ISO 179/1eU at 23°C): < 35 kJ/m².

Product at the lower end of the mechanical performance.

Optimized (high) mechanical properties (tensile strength,

tensile modulus and impact strength) by matching the system

consisting of the glass fiber sizing (chopped strands), coupling

agent, PP matrix and other additives.Example: 30% glass fiber reinforced homo PP product:

Tensile strength at break (ISO 527-2) up to ~ 110 MPa.

Unnotched Charpy impact strength (ISO 179/1eU at 23°C) up to ~ 60

kJ/m². Product with the highest feasible performance.


GF reinforced PP products / targets

Target 1 products exhibit up to 40% lower (!)

mechanical properties (initial values) vs. target 2

products,

but target 1 products fully comply with the UL

standards 2157 and 749.

and target 2 products not always do comply with the

UL standards 2157 and 749 because of < 50 %

retention especially of the impact strength after

138 days laundry or dishwasher detergent

solution immersion.

(See diagrams for 2 different 20% GF reinforced PP products

with 2 different targets)


Tensile properties of different 20% Glass fiber reinforced PPmaterials over 40 days hot water immersion

Hot water test ( demin. water at 95°C )

of 2 different 20% GF reinforced Hostacom products

with identical glass fibers

40

45

50

55

60

65

70

75

80

85

0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40Immersion period (days)

Te

ns

ile

str

en

gth

at

bre

ak

(MP

a)

HC U HC C (A208571) HC C (1M12AE20)

Tensile strength of mineral filled products < 40 MPa

UL 2157 approved

does also comply with UL 2157


Charpy impact strength (ISO 179/1eU) of diff. 20% Glass fiberreinforced PP materials over 40 days hot water immersion

Hot water test ( demin. water at 95°C )

of 2 different 20% GF reinforced Hostacom products

with identical glass fibers

15

20

25

30

35

40

45

50

0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40Immersion period (days)

Ch

arp

y i

mp

ac

t u

nn

otc

he

d,

23

°C (

kJ

/m²)

HC U HC C (A208571) HC C (1M12AE20)

Range of < 50% retention of the impact strength

for HC U (initial value: 46,3 kJ/m² / 50% value: 23,2 kJ/m²)

UL 2157 approved

at the limit


Glass fiber - PP matrix interphaseHow to optimize the hot water resistance

Hot water / steam and hot watery detergent solutions impair the

glass fiber - PP matrix interface, but the mechanism of the fast

water migration into the specimens and wetting of the interface is

not well understood and identified.

One key parameter for the formulation of GF reinforced PP

products and the interaction with the coupling agents is the

glass fiber sizing (different from every glass fiber

manufacturer) which is including

silanes, binding resins, lubricants, antistats etc.

(see diagrams for different glass fibers from different suppliers but

identical Hostacom formulations)


Tensile properties of a 30% Glass fiber reinforced PP material withdiff. commercial glass fibers over 40 days hot water immersion

50

55

60

65

70

75

80

85

90

95

100

0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40


Tensile

strength

at bre

ak (M

Pa)

Hostacom G3 (identical formulation)

but with different commercial glass fibers

(different manufacturer / different sizings)


Charpy impact strength (ISO 179/1eU) of a 30% Glass fiber reinforced PPmaterial with diff. commercial glass fibers over 40 days hot water immersion

0

10

20

30

40

50

0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 33 35 37 39


Unnotc

hed C

harp

y im

pact str

ength

(kJ/m

²)

Hostacom G3 (identical formulation)

but with different commercial glass fibers

(different manufacturer / different sizings)

Initial value 48,5

final value ~ 24

Initial value 42,6

final value ~ 14

Products don‘t comply with UL 2157 / 749 !


Glass fiber functionalizing (sizing) and coupling

Sizing

(functional silane)

Coupling


Glass fiber - PP matrix interphaseHow to optimize the hot water resistance

Other parameters for the formulation of GF reinforced PP products

which affect the efficiency of the coupling and the water resistance

are

the coupling agent (functionalized / grafted PP) with the

degree of grafting, type of grafting, base resin (homo, heco, random), MW

and MFR of the resin etc.

and additives which can interact with the polar groups of the

glass fiber sizing and of the coupling agentsuch as polar release agents.


Conclusion

But in spite of all improvements of GF reinforced products and

independant from the initial values of the mechanical properties (tensile

strength and impact strength) for a defined glass fiber reinforced grade

(with a defined glass fiber concentration and a defined PP matrix) the

mechanical properties seem approaching asymptotically to a lowest limit

over the long term hot water / deteregent immersion.

Hot water immersion (95°C)

20% GF reinforced Hostacom products

40

60

80

0 30 60 90 120Immersion period (days)

Te

ns

ile

str

en

gth

at

bre

ak

(M

Pa

)

This lowest limit is that

mechanical property of a

not coupled GF reinforced

PP product in practice.


Target for GF reinforced PP products

In principle the current situation of glass fiber reinforced PP products for

applications exposed to hot water and watery detergent solutions is less

satisfying. For CAE constructions engineers would like to use mechanically

optimized products to reduce the wall thickness of injection moulded parts

(saving of weight, costs, cycle time etc.). But over a longer immersion

period currently the properties could be maintained only for less optimized

products.

0

20

40

60

80

0 30 60 90 120Immersion period hot water 95°C ( days)

Te

ns

ile

str

en

gth

at

bre

ak

(M

Pa

)

20% mineral filled homo PP

20% glass fiber reinforced homo PPs


US clothes dryer which comply with UL 2158

HotHot airair doesn‘tdoesn‘t affectaffect thethe mechanicalmechanical

propertiesproperties of GF of GF reinforcedreinforced PPPP productsproducts

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Lastpictu

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Einsatz optimierter Glasfaser-verstärkter PP-Produkte ...amk/files/Mecklenburg_2003.pdf · Glass fiber reinforced PP products in principle can be developed / optimized with 2 different