prepreg compression molding for high volume … · 2014-08-31 · momentive specialty chemicals,...

Automotive Composites Conference Exhibition

Novi, September 09-11 2014

Prepreg Compression Molding for high volume manufacturing of Lightweight Epoxy Automotive

Structures

Advances in Thermoset Composites

Principal Author: Alex Schmidt Presenter: Stephen Greydanus

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Momentive Specialty Chemicals, Inc. Confidential Information

Momentive is a $7.8 Billion Specialty Chemicals and Materials Company

Momentive Heritage Businesses Momentive Today

Sales: US $7.8 Billion Headquarters: Columbus, Ohio USA Manufacturing facilities: 100+ worldwide Employees: 10,000 Customers: Serving 20,000 around the globe

#1 #1 #1 #2

#1 #1 #2#1

Epoxy ResinsGlobal

Specialty Epoxy

BaseEpoxy

QuartzGlobal

SiliconesGlobal

Oilfield Proppant ResinsGlobal

Forest Product Resins Global

Versatic™ Acids & Derivatives Global

Phenolic Specialty ResinsGlobal

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Composite Technology Shifts in Support of Higher Volume and/or Higher Performance

Prepreg

Structural SMC

SMC

Liquid Compression Molding and

RTM

Perf

orm

ance

Capable Annual Build Rate 3


Different CFRP molding processes

High Pressure RTM-Process Fast cycle times can be achieved with newly developed fast cure resin systems. Production of difficult 3D shapes possible

Prepreg Compression Molding Easy to control compression molding process. Fast cure cycles, high glass transition temperatures and outstanding mechanical properties

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Prepreg compression molding process and in-process recycling route

60 sec 10 sec 180-300 sec 10 sec

Total cycle time: 260-380 sec

Cutting of waste into 25-50mm pieces

In-process recycling route Allows to use prepreg waste as high quality molding compound

Molding Compound Sheet

Place charge in mold (~80% coverage)

Prepreg Compression Molding Fast process approaching cycle times of high pressure RTM

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Process parameters of Prepreg compression molding and high pressure RTM

Prepreg Compression Molding

High Pressure RTM

Raw materials Newly developed fast curing prepreg system with CF or GF reinforcement

Dry Fabric (NCF, Weave, choped fiber mat…); Fast cure 2 component resin

Achievable Fiber volume content (FVC)

≤ 65% ≤ 55%

Resin System Epoxy Epoxy

Preforming One sided tool + vacuum or two sided tool + press (no heating)

Heated two sided tool + press

Molding pressure 10-50bar 10-80bar

Cure time at °C 3-5 min at 135-170°C 1.5-5 min at 110-130°C

Typical Tg 135-160°C 110-130°C

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Advantages of Prepreg compression molding process

Fast cycle times (<4min) possible Easy to control process Utilization of existing equipment (presses) In house prepreg as viable approach to further reduce cost Hot melt system (not requiring any solvents) Fast and easy preforming Can be used to produce structural as well as exterior parts/components Hybrid parts with metal or SMC possible No handling of dry fibers VOC-free systems

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Automotive applications for prepregs

Dash panel

Hood

Body side

Roof

Inner Structure

A, B & C Pillars Body & Structural parts

Underbody & floor

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EPIKOTE™ Resin 06425 EPIKURE™ Curing Agent 06465 EPIKURE™ Catalyst 06825

Possible Applications: Structural applications Reinforcement for metal parts e.g.

B-pillar

Good surface quality for exterior applications (may require adjusted molding cycle)

Cure temperature

Cure time

Tg midpoint, DSC 2nd run

Tg, DMA E´onset

135-150°C 3-5 min 135°C 135-140°C

Momentive fast cure resin systems

Cure temperature

Cure time

Tg midpoint, DSC 2nd run

Tg, DMA E´onset

150-170°C 3-5 min 150°C 150-160°C

EPIKOTE™ Resin 06465 EPIKURE™ Curing Agent 06465

EPIKURE™ Catalyst 06865

Possible Applications: Good surface quality + fast cure

cycle for exterior applications

Good mechanical properties for structural applications

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100

1,000

10,000

100,000

1,000,000

10,000,000

40 50 60 70 80 90 100 110 120

Visc

osity

[mPa

s]

Temperature [°C]

Viscosity of new resin systems



Heating rate 2K/min

Resin viscosity has been optimized for compression molding process • Controlled resin flow leads to homogenous parts with good surface quality • Faster curing than standard prepreg formulations

Conventional Prepreg System

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Storage stability at 20°C

Uncured Tg determined by DSC (10K/min)

Prepreg resin systems exhibit good storage stability at ambient temperatures as shown by the evolution of uncured Tg over time

• Shelf life at ambient temperature: > 2 weeks • Shelf life at -18°C: 6 months

0 1 2 3 4 5 6 7 8 9

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0 2 4 6 8 10 12 14 16

Unc

ured

Tg

[°C]

time [d]



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Fast cycle time demonstrated by Dielectric Analysis

2 4 6 8 10 12 14 16Time /min

6.5

7.0

7.5

8.0

8.5

9.0

9.5

10.0

10.5

Log ion visc. /Ohm*cm

60

80

100

120

140

Temp. /°C

-2.0

-1.5

-1.0

-0.5

0.0

0.5

1.0

d(Log ion visc)/dt /((Ohm*cm)/min)

Momentive Prepreg+CF mit TMS gemessen

Log ion visc. (1 Hz)

Log ion visc. (10 Hz)Log ion visc. (100 Hz)Log ion visc. (1 kHz)

Log ion visc. (10 kHz)d(Log ion visc)/dt (1 Hz)

Temp.

Temp.

End: 3.0 min

Percent Cure: 99.594 %Percent Cure: 91.894 %

Peak: 1.5 min

Dielectric analysis - measuring changes in the electrical properties of polymers during processing - is used to investigate the curing behavior of thermosetting resin systems. Measurements taking directly inside the compression mold show the fast cure properties of the resin system.

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Fast cycle time video

Video containing: 1. Preform placement 2. Press close 3. Press opening 4. Demold Ca. 90sec (time lapse for cure process)

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Retention of flexural modulus at elevated temperatures

50

55

60

65

70

75

80

85

90

95

100

100 110 120 130 140 150 160 170 180

Rela

tive

Flex

. Mod

ulus

[%]

Temperature [°C]

Easy de-molding possible

Sufficient stiffness for painting and adhesive bonding

Modulus retention of High Tg system allows painting and adhesive bonding processes at temperatures between 150C and 175C



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Momentive fast cure prepreg properties

Process parameters Unit EPIKOTE™ Resin 06425 EPIKURE™ Curing Agent 06465 EPIKURE™ Catalyst 06825


Test Method

Molding temperature °C 135-150 150-170

Curing time min 3-5 3-5

Glass Transition Temperature

Midpoint DSC 2nd run

E´onset DMA

°C

°C

135°C

135-140°C

155-158°C

153-160°C

ISO 11357-1

Prepreg Tack - Very low Very low

Shelf life 23 °C

-18 °C

Weeks

months

2

6

2

6

Tack life @ 23°C days 5 5

ILSS pure UD laminate (FVC ~59%) MPa 91 90 ISO 14130

Flexural Strength pure UD laminate (FVC ~59%)

MPa 1610 1654 ISO 14125

Flexural Modulus pure UD laminate (FVC ~59%)

GPa 108 110 ISO 14125

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Application technology examples

R-Class roof segment:

Flat panel – Compression molded Roof segment- Compression molded

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Presenter

Presentation Notes

Automobilstruktur mit möglichen anwendungen für prepreg


Paint system used for demonstrator parts

Sanding P800

Primer and Basecoat

Sealer

Clear coat

UD CF surface

Clear coat contains Cardura™ Glycidyl ester monomer 17


E-Coat simulation (parts stable up to 200°C)

Demonstrator part was heated up to 200°C for 30 min to simulate E-Coat Part showed no deformations and was successfully painted

Small panel heated up to 210°C for 2 hours As result part only shows slight yellowing

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Prepreg scrap in-process recycling

Prepreg waste resulting from the cutting of preforms can be recycled as high quality molding compound

• Waste is cut into pieces of 25 – 50mm length • The resulting material can be placed into a mold and

compression molded (SMC like process) • Approximately 80-90% of mold need to be covered to achieve good results • Parts exhibit good mechanical properties and high heat resistance • Molding compound can be used in combination with prepreg to

produce hybrid parts

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Conclusion

New prepreg systems allow rapid manufacturing of automotive parts due to fast cure cycles

Prepreg compression molding can be complementary offering to RTM Suitable for structural and exterior applications

Systems offer:

• Good storage stability • High mechanical performance • High glass transition temperature • Good surface quality

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EPON™ Epoxy Resins EPIKOTE™ Epoxy Resins EPIKURE™ Curing Agents

Heloxy™ Additives are registered trademarks of

Momentive Chemicals Inc. or an affiliate of Momentive

Specialty Chemicals Inc.

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DISCLAIMER The information provided herein was believed to be accurate at the time of preparation or prepared from sources believed to be reliable, but it is the responsibility of the user to investigate and understand other pertinent sources of information, to comply with all laws and procedures applicable to the safe handling and use of any product of Momentive Specialty Chemicals Inc. or Momentive Performance Materials Inc. and/or their respective subsidiaries (individually, and collectively, “Momentive”) and to determine the suitability of any Momentive product for its intended use. All products supplied by Momentive are subject to Momentive’s terms and conditions of sale. MOMENTIVE MAKES NO WARRANTY, EXPRESS OR IMPLIED, CONCERNING THE PRODUCT OR THE MERCHANTABILITY OR FITNESS THEREOF FOR ANY PURPOSE OR CONCERNING THE ACCURACY OF ANY INFORMATION PROVIDED BY MOMENTIVE, except that the product shall conform to Momentive’s specifications. Nothing contained herein constitutes an offer for the sale of any product.

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prepreg compression molding for high volume … · 2014-08-31 · momentive specialty chemicals,...

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