COMDI‘ESSiOI‘I
`Molding
`
`DaViS / Gramann /
`
`Osswald / Rios
`
`
`
`
`
`MacNeiI Exhibit 2077
`
`Yita v. MacNeiI IP, lPR2020-01139
`
`Page 1
`
`MacNeil Exhibit 2077
`Yita v. MacNeil IP, IPR2020-01139
`Page 1
`
`

`

`
`
`
`
`
`
`Bruce A. Davis / Paul J. Gramann/
`
`Tim A. Osswald / Antoine C. Rios
`
`Compression Molding
`
`HANSER
`Hanser Publishers, Munich
`Hanser Gardner Publications, 1110., Cincinnati
`
`
`
`MacNeiI Exhibit 2077
`
`Yita v. MacNeiI IP, lPR2020-01139
`
`Page 2
`
`MacNeil Exhibit 2077
`Yita v. MacNeil IP, IPR2020-01139
`Page 2
`
`

`

`The Ant/tars:
`Dr. Bruce A. Davis. Dr. Paul J. Gramann, Dr. Antoine C. Rios
`all: The Madison Group, Polymer Processing Research Corp.. 505 S. Rosa Rd, Suite 124, Madison. WI 53719—1265
`Prof. Dr. Tim A. Osswald. Polymer Engineering Center, University ofWisconsin — Madison, Dept. of Mechanical
`Engineering, 1513 University Avenue, Madison WI 53706, USA
`
`Distributed in the USA and in Canada by
`Hanser Gardner Publications, Inc.
`6915 Valley Avenue, Cincinnati, Ohio 45244-3029, USA
`Fax: (513) 527-8801
`Phone: (513) 527-8977 or 1-800-950-8977
`Internet: http://www.hanscrgardner.corn
`
`Distributed in all other countries by
`Carl HanserVei-lag
`Postfach 86 04 20, 81631 Mfinchen. Germany
`Fax: 149 (89) 98 48 09
`Internet: http://www.hanser.de
`
`The use of general descriptive names, trademarks, etc.. in this publication, even if the former are not especially
`identified, is not to be taken as a sign that such names. as understood by the Trade Marks and Merchandise Marks Act,
`may accordingly be used freely by anyone.
`
`While the advice and information in this book are believed to be true and accurate at the date of going to press,
`neither the authors nor the editors nor the publisher can accept any legal responsibility for any errors or omissions
`that may be made. The publisher makes no warranty, express or implied, with respect to the material contained herein.
`
`Library of Congress Catalogingein—Publication Data
`
`Compression molding / Paul J. Gramann
`p. cm.
`ISBN 1—56990-346—8 (Hardcover)
`1. Thermosetting plastics. 2. Reinforced plastics.
`
`[et al.].
`
`Printed and bound by Kosel, Kempten, Germany To ourfamilies
`
`J
`
`I. Gramann. Paul
`
`TP1180.T55C66 2003
`668.4’22 rdc2l
`
`2003007485
`
`Bibliografische Information Der Deutschen Bibliothck
`Die Deutsche Bibliothek vcrzcichnet diese Publikation in der Deutsehen Nationalbibliografie;
`detaillierte bibliografische Daten sind im Internet fiber <hflm’mflhflg} abrufbar.
`ISBN 3—446—22 166-2
`
`All rights reserved. No part ofthis book may be reproduced or transmitted in any form or by any means, electronic or
`mechanical, including photocopying or by any information storage and retrieval system, without permission in
`writing from the publisher,
`
`© Carl Hanser Verlag, Munich 2003
`Production Management: Oswald Immel
`Typeset by Angela Ospina-Garcia, USA
`Coverillustration by Mike Shinedling
`Coverdesign: MCP - Susanne Kraus GbR, Holzkirchen, Germany
`
`MacNeil Exhibit 2077
`
`Yita v. MacNeil IP, |PR2020—01139
`
`Page 3
`
`MacNeil Exhibit 2077
`Yita v. MacNeil IP, IPR2020-01139
`Page 3
`
`

`

`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`18 Introduction
`
`exchange membrane (FEM), which uses numerous highly conductive bi-polar
`plates that contain complex patterns of flow channels. The plates perform three
`functions: manage the hydrogen on one side and the oxygen (air) on the other,
`contain the cells where the reaction will take place, and conduct the current
`produced. Originally,
`the plates were individually machined from materials
`such as isostatic graphite, aluminum, stainless steel, and titanium making the
`plates extremely expensive. Once again plastic was looked at to replace metal,
`and in doing so, made the product significantly less expensive while creating a
`more superior product. The final product has to have nearly exacting
`dimensions with extreme flatness and creep, thermal and corrosion resistance,
`and not leach—out contaminants. All this has to be met while processing a
`highly filled material that contained evenly mixed conductive graphite. Since
`each fuel cell contains numerous plates, the volume potential 'was enormous
`and processing had to be completely automated. The obvious choice for this
`operation is the injection-compression process. The current market potential
`for this application is huge. One percent penetration of the automotive market
`50 and 100 million pounds of fiber reinforced materials
`[8]. This is one example of how compression molding, or variants of it, will be
`used to mold plastic materials in the future.
`
`References
`
`1.
`]acobi, H.R., Kunststoffe, 55, 3, 173, (1965)
`Dubois, 11-1., Plastics History U.S.A., Cal-mers Books, Boston, (1972).
`a ,
`3. Northrup, 1=.s., us. Patent 1,158,830, (1915).
`4. Report, SMC/ BMC European Alliance, Nov. 2002
`5. Crain’s International Newspaper for the Plastics Industry, August (2002).
`6. Fenichell, 5., Plastic, HarperBusiness, New York, (1996).
`Automotive Composites
`7. Application of Carbon Fiber SMC for the 2003 Dodge —
`Conference (2002).
`8. Composites Technology Sept}rOct (2001).
`
`
`
`
`
`Compression Molding Materials
`
`Compression molding material
`..
`
`s are often com lex reci
`
`polypp pp; .p at: passes
`satisfies In some
`and reinfgrc’n -f'b e bulk of the material is made up of a polymer with Of'll e
`olvmer
`1111118 .Ilers. Th1s chapter will start by discussing the fundame atal1 er
`Ema ound a er(1ia s. This is
`followed by the description of
`th
`II
`'8 0f
`molding 3011:1850 dgripngcginpression molding Here we will disSusZagfdl:
`.
`un
`, bulk moldin
`I
`e
`mi
`,
`g com ound BM
`(EFTSXCZS tigergiiplaftltf’
`(EMT)! and long 1ciberpreinforded flierrilglsiislaslfi:
`.
`0
`behavior of composites.
`C apter we present fundamentals Of mechanical
`
`e
`
`2.1
`
`Introduction to Polymers
`
`
`
`
`
`
`
`
`
`
`AS the w
`'
`very higli’rrliidlzfiiflsugggs’ts’ P01Ymersi are materials composed of m01€cules of
`"mm-omelccules, “1631;112:155;Thesellarge molecules are generally referred to as
`of that
`.
`-
`.
`a erla . properties of pol mers and
`-
`-
`with viliiiififyefimg methods are attributed to their molZcular structtldieveflfliatlhty
`tier-,5:
`the mEStYmers and plastrcsl are processed makes them, for man. a e Ease
`their ability to bseodlight Site; material tOdaY- BGCause of their low debsilfp bid
`to traditional mat Ellie and molded at relatively low temperatures comyared
`.of Choicg When ietna s such as metals, plastics and polymers are the ma};
`'
`1
`aspect usually cailreIdifil-ziilgi 5:22:81] Pg? into a Single componentHa (1:53:11
`
`
`traditionill
`SO I
`(I 1011'
`ad! Parts and Com one
`'
`,
`3’ been made of wood, metal, ceramic 01' glass 1331'“: $525335: hall]:
`
`I
`w1
`
`plastics on
`'
`‘
`a daily bas1s P.
`olymers can be
`I
`‘
`'
`Fromthec
`k
`_
`p ced into either a thermoplastic,
`1
`“—5—__——
`a
`'
`
`2
`Ice , pol: which means many, and mcros which means parts
`v
`[3 ast
`‘
`'
`q '1
`V
`
`I} e term 1
`C5 deg
`1
`Crlbe,
`: Compound of polymers and aIlOuS addlll 85
`
`
`
`
`MacNeil Exhibit 2077
`.
`Ylta v. MacNeil IP, |PR2020-01139
`
`Page 4
`
`MacNeil Exhibit 2077
`Yita v. MacNeil IP, IPR2020-01139
`Page 4
`
`

`

`
`
`
`
`Compression Molding Materials
`20
`———_———————__
`
`thermoset or elastomer category. Thermoplastics in turn flave a specizlil1:815:13:
`‘
`'
`tomers. However, all t ese ma era
`a
`which are called thermoplastic elas
`1
`195 are
`lecules. Some of these m0 ecu
`on that the
`are made of huge mo
`_
`.
`Eggsslinked which means that each molecule can move freely r’elativrler1to its1
`neighbors and others are crosslinked, which means that bridgdes , or Eafifiii
`.
`_ ,
`.
`_
`'
`'
`lecules. Thermoplastlcs an un vu
`s interconnect the polymer mo
`.
`1ellIallgtomers
`are uncrosslinked. Vulcanlzed rubber,
`or
`elastomers,
`and
`thermosets are cross-linked.
`
`.
`
`nfi
`
`
`
`
`
`
`t influence on the
`.
`.
`ration of the polymer molecules hasa grea
`proprilr‘li:ofgtile polymer component. The configuratlpnt1gives tire irliforgiatior;
`'
`‘
`"
`'
`tion 0
`e moecue.
`urin
`'
`b t
`the distribution and spatial orgaruza .
`.
`_
`aol;merization it is possible to place the X groups on the carbgn (22:32:
`backbone in different directions. The order inhwhich ttliey ariapgrrggonilsmafier
`‘
`'
`‘
`'de
`oups t at are p ace
`.
`the tachczty. The polymers With 51
`gr '
`h
`Slde are
`'
`cle groups are all on t e same
`are called atactzc. The polymers whose.51
`.
`.d
`u s are
`'
`'
`h regularly alternating 31 e gro p
`called zsotactlc, and those molecules w1t
`.
`s for
`.
`_
`'
`'
`‘
`the three different
`tact1c1ty case
`called syndwtactic. Figure 2.1 shows
`th
`of
`d
`.
`d
`
`'
`‘
`'
`e
`egree
`'
`termines
`lene. The tact1c1ty m a polymer
`.
`Eelgfal‘lifulfy that a polymer can reach. For example“ polypropylene Wiltthb:Egg?
`
`igtactic content will reach a high degree of crystallrmty and as a resu the final
`
`
`strong and hard. Branching of the polymer chains also influences
`
`structure, crystallinity and properties of the polymerlc material.
`
`
`2.1 Introduction to Polymers
`
`21
`
`2.1.2 Thermoplastic Polymers
`
`there are
`if
`from monomers occurs
`The formation of macromolecules
`unsaturated carbon atoms (carbon atoms connected with double bonds), or if
`there are monomers with reactive end—groups. The double bond, say in an
`ethylene monomer, is split which frees two valences per monomer and leads to
`the formation of a macromolecule such as polyethylene. This process is often
`referred to as polymerization. Similarly, monomers
`(R)
`that possess two
`reactive encl~groups (bifunctional) can react with other monomers (R') that also
`have We other reactive end-groups that can react with each other, also leading
`to the formation of a polymer chain.
`
`2.1.3 Amorphous Thermoplastics
`
`e
`
`.
`
`Amorphous thermoplastics, with their randomly arranged molecular structure,
`are analogous to a bowl of Spaghetti. Due to their random structure,
`the
`characteristic size of the largest ordered region is on the order of a carbon—
`carbon bond. This dimension is much smaller than the wavelength of visible
`light and therefore generally makes amorphous thermoplastics transparent.
`Figure 2.2 [1]
`shows the shear modulus,
`(3', versus temperature for
`polycarbonate, an amorphous
`thermoplastic that
`is
`injection—compression
`molded into compact discs. The figure shows two general regions: one where
`the modulus appears fairly constant3, and one where the modulus drops sigm-
`ficantly with increasing temperature. With decreasing temperatures,
`the
`
`material enters the glassy region where the slope of the modulus approaches
`
`zero. At high temperatures the modulus is negligible and the material is soft
`
`enough to flow. Although there is not a clear transition between ”solid” and
`
`”liquid,"
`the temperature that divides the two states in an amorphous
`
`thermoplastic is referred to as the glass transition temperature, Tg. For the
`polycarbonate in Fig. 2.2, the glass
`transition temperature is approximately
`
`
`150 r’C. Although data is usually presented in the form shown in Fig. 2.2, it
`
`should be mentioned here that the curve shown in the figure was measured at a
`
`constant frequency. If the frequency of the test is increased—reducing the time
`
`scale— the curve is shifted to the right since higher temperatures are required to
`
`achieve movement of the molecules at the new frequency; Figure 2.3 [2]
`
`demonstrates this concept by displaying the elastic modulus as a function of
`
`temperature for polyvinyl chloride at various test frequencies. A similar effect
`
`is observed if the molecular weight of the material is increased. The longer
`
`
`molecules have more difficulty sliding past each other, thus requiring higher
`temperatures to achieve ”flow.”
`
`
`
`Syndioiactic
`———________
`
`3 When plotting G' versus temperature on a linear scale, a steady decrease of the modulus is observed.
`Different polypropylene structures.
`
`
`
`
`MacNeil Exhibit 2077
`
`Yita v. MacNeil IP, |PR2020-01139
`
`Page 5
`
`MacNeil Exhibit 2077
`Yita v. MacNeil IP, IPR2020-01139
`Page 5
`
`

`

`22
`
`Compression Molding Materials
`
`2.1 Introduction to Polymers
`
`23
`
`2.1.4 Semi-Crystalline Thermoplastics
`
`Semi—crystalline thermoplastic polymers show more order than amorphous
`thermoplastics. The molecules align in an ordered crystalline form as shown
`for polyethylene in Fig. 2.4. The crystalline structure is part of a lamellar crystal
`which in turn forms the spherulites. The formation of spherulites during
`solidification of semi—crystalline thermoplastics is covered in Chapter 3. The
`schematic in Fig. 2.5 shows the general structure and hierarchical arrangement
`in semi—crystalline materials. The spherulitic structure is the largest domain
`with a specific order and has a characteristic size of 50 to 500 um. This size is
`much larger than the wavelength of visible light, making semi-crystalline
`materials translucent and not transparent.
`
`However, the crystalline regions are very small with molecular chains
`comprised of both crystalline
`and amorphous
`regions. The degree of
`crystallinity in a typical thermoplastic will vary from grade to grade. For
`example, degree of crystallinity depends on the branching and the cooling rate.
`
`1 o4
`
`103
`
`._|. OM
`
`10
`
`
`
`Shearmodulus,6’(MPa)
`
`Figure 2 2
`
`
`
`
`
`
`
`
`
`
`100
`
`_50
`
`0
`
`50
`
`100
`
`150
`
`200
`
`Temperature, T (00)
`
`Shear modulus of polycarbonate as a function of temperature.
`
`
`Figure 2.4
`
`Schematic representation of the Crystalline structure of polyethylene.
`
`
`120
`80
`40
`
`Temperature, T (QC)
`F'gure 2 3 Modulus of polyvinyl chloride as a function of temperature at varlous
`1
`.
`
`test frequencies.
`
`160
`
`0
`
`MacNeiI Exhibit 2077
`
`Yita v. MacNeiI IP, lPR2020-01139
`
`Page 6
`
`MacNeil Exhibit 2077
`Yita v. MacNeil IP, IPR2020-01139
`Page 6
`
`

`

`
`
`the amorphous regions
`decreases below the glass transition temperature,
`within the semi—crystalline structure solidify, forming a glassy, stiff and in
`some cases brittle polymer.
`
`2.1 Introduction to Polymers
`
`25
`
`104
`
`a 103
`D.
`
`102
`
`10
`
`E ‘
`
`om
`
`.
`23
`‘8
`e
`is(D.C
`(I)
`
`.100
`
`—50
`
`0
`
`50
`
`100
`
`150
`
`200
`
`Figure 2.6
`
`Shear modulus of a polypropylene as a function of temperature.
`
`Temperature, T (0C)
`
`2.1.5 Thermosets and Cross-Linked Elastomers
`
`Thermosets, and some elastomers, are polymeric materials that have the ability
`to cross—link. The cross—linking causes the material to become resistant to heat
`after
`it has solidified. A more in—depth explanation of
`the cross-linking
`Chemical reaction that occurs during solidification is given in Chapter 3.
`
`The cross—linking usually is a result of the presence of double bonds that
`break, allowing the molecules to link with their neighbors. One of the oldest
`thermosetting polymers is phenol-formaldehyde, or phenolic. Figure 2.7 shows
`the chemical symbol representation of the reaction, and Fig. 2.8 shows a
`schematic of the reaction. The phenol molecules react with formaldehyde
`molecules to create a three-dimensional cross—linked network that is stiff and
`
`strong. The by—product of this chemical reaction is water.
`
`
`
`Compression Molding Materials 24
`
`a = 0.736 nm
`b = 0.492 nm
`6 = 0.254 nm
`
`Lamella
`20 to 60 nm
`
`Crystal Iamella
`
`Spherulite
`= 50 to 500 pm
`
`
`
`—— Polymer component
`
`Figure 2.5
`
`the general molecular
`on of
`representati
`Schematic
`arrangement of typical semi-crystalline materials.
`
`structure
`
`and
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`mic shear modulus versus temperature for a
`Figure 2.6 [1] shows the dyna
`ly compression molded semi—crystalllne
`polypropylene;
`the most common
`ed at one test frequency.
`this curve presents data measur
`thermoplastic. Again,
`.
`_
`sitions: one at about —5 0C, the glass
`The figure clearly shows two dlstmct tran
`5 0C, the melting temperature. Above
`transition temperature, and another near 16
`gible and the material W111
`'
`, the shear modulus is negli
`the m€1tmg temperatUIe
`begins to develop as the temperature decreases
`flow. Crystalline arrangement
`lting and glass
`transition
`below the melting point. Between the me
`leathery solid. As the temperate-Ire
`temperatures, the material behaves as a
`
`
`
`
`MacNeil Exhibit 2077
`
`Yita v. MacNeil IP, |PR2020-01139
`
`Page 7
`
`MacNeil Exhibit 2077
`Yita v. MacNeil IP, IPR2020-01139
`Page 7
`
`

`

`26
`
`Compression Molding Materials
`
`Symbols
`
`OH
`
`OH
`
`2.2 Compression Molding Material Preparation
`
`2.2 Compression Molding Material Preparation
`
`0
`
`H
`
`H
`
`:*:+HJ‘5\H+HtH
`
`H
`H
`Formaldehyde
`Phenol
`Phenol
`iOH
`OH
`H
`2 31:3.
`
`H
`
`H
`
`H
`
`+ H20
`
`
`
`
`27
`
`
`
`
`
`
`
`
`
`
`A wide variety of polymeric materials are compression molded. This includes
`thermosets, thermoplastics, and elastomers, of which a vast majority are fiber
`reinforced to add mechanical strength to the part. The use of these materials
`permeates many industries with 2.28 billion pounds consumed in 2002.
`
`Compression molding resins can be thermoplastic or thermoset plastics
`depending on the application. The resin matrix binds all the reinforcements and
`fillers together in a structural component. The resin matrix also protects the
`different components from external factors and spreads the structural loads
`between the reinforcements and fillers.
`
`2.2.1 Thermosetting Resins
`
`Unsaturated polyester (UP) is by far the most commonly used thermoset resin
`for compression molding. This material has good strength properties while
`maintaining a high resilience that is needed in many demanding applications.
`Another advantage of polyesters over other thermosetting resins is that they
`can be pigmented while in a liquid form. Vinylesters are used in more severe
`conditions where a higher strength and more resilient material is needed. Since
`Vinylesters contain fewer ester groups than polyesters,
`they exhibit better
`resistance to water and chemicals. The cure times of Vinylesters are typically
`quicker than other thermosets, reducing mold time and cost to produce the
`part. However,
`the cost of Vinylester
`resin tends to be higher.
`In high
`temperature applications (175 OC) and for components with thick regions,
`epoxy is a viable option. Epoxies generally exhibit higher mechanical
`properties and resistance to the environment. However, their resistance to acids
`is less than the one of polyesters and they are more expensive than polyesters
`and Vinylesters. Phenolic resin systems have a clear advantage over polyesters,
`epoxies, and Vinylesters in applications where fire safety is a concern. In a
`developed fire the emission of smoke is quite low. Phenolics exhibit long—term
`durability and resistance to hydrocarbon and chlorinated solvents, and show
`high strength and modulus properties similar to that of polyesters. Table 2.1
`shows properties for the various thermosetting resins discussed here.
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`OH
`
`CH2
`OH
`
`TCHE
`
`OH
`
`—(3H
`
`OH
`iiOH
`_
`C_H2 O CHQ‘CHZ
`CH2 i
`CH2QCH2 CI CH2—
`
`#
`
`H
`
`' H
`C 2
`
`OH
`
`OH
`
`HacU
`
`CH2
`
`CH2"
`
`OH
`
`Figure 2.7
`
`Symbolic representation of the conden
`.
`formaldehyde resms.
`
`sation polymerization of phenol-
`
`
`
`
`
`
`
`U0
`
`
`+ H20
`
`
`
`
`0P
`
`
`on of the condensation polymerization of phenol-
`Figure 2.8
`Schematic representati
`formaldehyde resins.
`
`
`
`
`MacNeil Exhibit 2077
`
`Yita v. MacNeil IP, |PR2020-01139
`
`Page 8
`
`MacNeil Exhibit 2077
`Yita v. MacNeil IP, IPR2020-01139
`Page 8
`
`

`

`Compression Molding Materials
`28
`___________—_———-————#
`
`
`
`Thermosets Properties for Thermosetting Resins___—-—— Table 2.1
`Material
`Specific gravity W Elongation0 at break
`MPa
`Aw
`
`
`Epoxy
`Phenolic
`
`1.10-1.20
`1.00-1.25
`
`40785
`60-80
`
`1.5-8.0
`1.8
`
`2.2 Compression Molding Material Preparation 29
`
`Table 2.2
`
`Thermoplastics Properties of Filled and Unfilled Thermoplastic Com—
`pression Molding Resins
`
`Polymer
`
`Polypropylene
`(PF)
`
`Polyamide 6
`(PA 6)
`
`Polyamide 66
`(PA 66)
`
`Glass fiber
`content ("/0)
`none
`10
`30
`10*
`30*
`
`none
`15
`30
`
`none
`13
`30
`
`Specific W Elongation at
`gravrty
`strength (MI’a)
`break ("/0)
`0.89
`34
`200.0
`0.98
`43
`4.0
`1.12
`47
`2.0
`0.98
`50-59
`4.0
`1.12
`68-83
`2.0
`
`1.12
`1.25
`1.37
`
`1.13
`1.23
`1.37
`
`81
`104
`166
`
`79
`97
`173
`
`30
`4.0
`3.0
`
`60
`4.0
`3.0
`
`WTW—U— 50—300
`teraphthelate (PET)
`30
`1.56
`158
`3.0
`* Chemically coupled: This compound uses a chemical sizing on the fiber to improve fiber—
`matrix bonding.
`
`2.2.3
`
`Functional Additives
`
`Additives are used to improve processing and mechanical properties of the
`compression molding materials. The most important additives for thermoset
`resins are initiators to start the chemical reaction,
`inhibitors to retard the
`reaction, and low profile additives to control shrinkage. The final compound
`used for compression molding contains up to 10% in weight of additives. Other
`additives of note are release agents (water based, calcium and zinc stearate),
`pigments (titanium oxide, carbon black, others),
`thickeners (metal oxides,
`calcium oxide, others), and property-enhancing additives.
`
`The most common additives used for thermoplastic resins are antioxidants,
`which are used to reduce material degradation during processing, UV
`stabilizers to improve resistance to UV radiation, pigments to color the final
`part, and lubricants to aid in demolding. Thermoplastic resins can also include
`various property-enhancing additives.
`
`2.2.3.1
`
`Initiators
`
`Sheet molding compounds are polymerized by a free radical reaction where the
`double bond of the polyester molecular chain reacts with the styrene monomer.
`
`Polyester
`
`Vinylester
`
`1.0-6.5
`30—75
`1.10—1.23
`1.12-1.13
`70—81
`3.0—8.0
`_____——_______
`
`resins used in composites are polyesters}
`Approximately 75% of all
`Unsaturated polyester
`is produced by condensation polymerization o
`dicarboxylic acids, glycols, and. anhydrides of dicarboxyhc adds [3].. (11:;
`resulting polymer is dissolved in a reactive monomer, typically styrene, W-
`lowers the overall viscosity of the product. This decreased viscosn'y also makes
`the polyester easier to process in many situations. After the polymer 15
`dissolved in the monomer the mixture is heated, causing the monomer to react
`with the polyester. The reaction changes the liquid mixture to a high viscosity
`res in.
`
`2.2.2
`
`Thermoplastic Resins
`
`Thermoplastics in general have lower weight and are tougher than thermosets.
`However, thermoplastics exhibit lower mechanical properties and higher ”2:?!
`in high temperature applications. The most common thermoplastic reams u
`f
`in compression molding is polypropylene (PP). Because of its high degree of
`crystallinity,
`the properties of PP can be greatly enhanced by the addition 0
`fillers and reinforcements. For more demanding applications, such as higher
`temperatures and loads, polyamide (PA) and polyethylene terephthalate (PET)
`are more suitable. Table 2.2 shows property enhancements after add-mg glass
`fiber reinforcement to typical thermoplastic resins [4].
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`MacNeil Exhibit 2077
`
`Yita v. MacNeil IP, |PR2020—01139
`
`Page 9
`
`MacNeil Exhibit 2077
`Yita v. MacNeil IP, IPR2020-01139
`Page 9
`
`

`

`
`
`2.2 Compression Molding Material Preparation 31
`
`Compression Molding Materials
`30
`____—___———-—-——-
`
`This crosslinking creates a three—dimensional structure that changes the highly
`viscous liquid resin into a hard thermoset solid. The source of the free radicals
`are referred to as initiators since they promote the curing reaction. The free
`radicals
`are usually produced when the
`initiator
`experiences
`a high
`temperature, i.e., temperature during molding.
`
`2.2.3.2
`
`Inhibitors
`
`matrix. The choice of size chemistry is important to balance fiber protection
`during processing and fiber-resin bonding. The choice of size is also dependent
`on the combination of fiber and resin used.
`
`Table 2.3
`
`Selected Properties of Common Fiber Materials
`
`WW Tensile Modulus
`E—glass
`2.54
`3.5
`72
`S—glass
`2.50
`4.5
`86
`Carbon
`1.77-1.80
`3.7—5.4
`33-42
`
`Inhibitors are used to retard the reaction of the resin to increase the shelf life of
`the SMC. Using inhibitors can greatly enhance the time before the SMC needs
`to be used. The inhibitor acts as an agent to control the reaction rate and 1n
`essence works against the initiator. The inhibitor constrains the polymer chain
`Pitch precursor
`in the initial stages of polymerization preventing the rate of reaction from
`Aramid
`becoming excessively large.
`
`Boron
`
`PAN precursor
`Carbon
`
`1.99-2.16
`
`1.44-1.47
`
`2.49—2.57
`
`1.7-2.2
`
`3.8
`
`3 .5
`
`55—100
`
`62-131
`
`400
`
`
`
`2.2.3.3 Low Profile Additives (LPA)
`2.2.4.1 Glass Fibers
`The most common types of LPA are thermoplastic resins. These additives-are
`used to reduce shrinkage related to the curing reaction and to improve. surface
`quality. Some of the common problems related to resin shrinkage are internal
`stresses, sink marks, voids, and bubbles.
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`2.2.4 Fillers and Reinforcements
`
`to lower shrinkage, reduce
`Fillers are mainly used as volume extenders,
`processing times, improve mechanical properties, and improve fire retardance.
`The most common fillers are calcium carbonate, clay, and material regrind,
`such as, recycled thermosets or thermoplastics. Fillers are 30% to 70% in weight
`of the final compound. The addition of fillers also lowers the cost of the
`compound by reducing the amount of resin, fiber, additives, and colorant used
`in the final formulation — the cost of the filler is usually a fraction of the cost of
`these materials.
`
`Reinforcements have a higher aspect ratio than fillers. The most common
`are glass, carbon, and aramid fibers. Fibers are added to improve the
`mechanical properties of the material. The combination between the properties
`of the fibers, fiber contents, length, orientation and fiber—resin bonding greatly
`affect the final properties of the compression molded part. Table 2.3 shOws
`mechanical properties and specific gravity of common available fibers.
`Fiber—resin bonding is affected by the chemistry of the fiber size or coating.
`Sizing is also used to protect
`fibers and reduce fiber breakage during
`processing. However, while protecting the fibers, sizing can hinder the wet-out
`of the fiber. Wet-out is the amount of surface contact between the fiber and the
`
`Glass fibers account for about 90% of the reinforcement in thermosetting resins.
`These fibers are produced by drawing or blowing molten glass, a mixture of
`quartz sand and additives, through small orifices at temperatures of 1400 to
`1600 OC. Glass fibers are available as continuous (roving), short (chopped),
`fiberglass textiles, mats, and various braided patterns. The length of the fiber
`has great effect on the strength of the product; generally, the longer the fiber
`the greater
`the strength. Depending on the composition, glass fibers are
`available in different variants. The E—glass variation is the most common and it
`exhibits
`excellent
`electrical
`insulation
`properties.
`For high
`strength
`applications, S—glass exhibits a tensile strength of 40% higher than E—glass and
`can be used at higher temperatures. However, S-glass is considerable more
`expensive than E—glass. Other variants are A—glass, C-glass, which are used in
`applications requiring good chemical
`resistance, D-glass used for high-
`performance electrical applications, and L-glass (lead glass) used for radiation
`protection.
`
`
`2.2.4.2 Carbon Fibers
`
`
`
`The main advantage of carbon fibers is their lower specific gravity, about 30%
`lower than glass fibers. They also have a low linear expansion coefficient and
`excellent conductivity. However, carbon fibers are more brittle and expensive
`than glass fibers. Carbon fibers are produced by heat treating (carbonizing) the
`precursor fibers at temperatures of 1000 to 3000 0C. Therefore, the quality and
`
`properties of carbon fibers depend on the composition of the precursor fibers.
`
`
`
`MacNeiI Exhibit 2077
`
`Yita v. MacNeiI IP, lPR2020—01139
`
`Page 10
`
`MacNeil Exhibit 2077
`Yita v. MacNeil IP, IPR2020-01139
`Page 10
`
`

`

`Compression Molding Materials
`32
`_——_—____——.—
`
`
`
`2.2 Compression Molding Material Preparation 33
`
`Precursor fibers are usually polyacrylonitrile (PAN) or pitch based. The heat
`treating temperature also affects the properties of the carbon fiber. High
`strength (HS) carbon fibers are heat treated at temperatures of up to 1700 0C and
`high modulus (HM) carbon fibers are heat treated at temperatures of up to
`3000 °C.
`
`2.2.4.3 Aramid fibers
`
`Aramid fibers, also known as Kevlar®, are based on aromatic amides resulting
`from the reaction of carboxolic acid and amine groups. These fibers generally
`have comparable strength to those of glass fibers, but up to twice the modulus
`and a specific gravity of about 45% lower than glass fibers. Aramid fibers
`exhibit high thermal
`stability,
`low conductivity, and good resistance to
`chemicals, except strong acids and alkalies. Aramid fibers can be used at
`temperatures up to 200 °C, any prolonged used above 175 0C will degrade its
`mechanical properties. Aramid fibers must be coated to protect them from
`moisture and UV light over a long period of time.
`
`2.2.5
`
`Compounded Materials
`
`The compounded material is the product that will be placed in the compression
`molding mold. This compound is a mixture of the resin matrix with numerous
`additives,
`fillers, and reinforcements. Depending on the type of
`resin,
`thermoplastic or thermosetting, and on its delivery form, it can be divided into
`four main compounds: SMC and BMC for thermosetting resins and LFT and
`GMT for thermoplastic resins.
`
`2.2.5.1 Sheet Molding Compound (SMC)
`
`The production of SMC generally involves two distinctive steps: compounding
`of the resin and additives, and the fabrication of the SMC sheet. During
`compounding all ingredients, except fibers, are mixed together to form a paste.
`Various thermosetting resins can be used for the paste, including, unsaturated
`polyester, vinyl ester, epoxy, phenolic, to name a few.
`
`
`
`In the compounding process, the resin ingredients are pre—mixed in two
`different batches, referred to as A—side and B—side, as presented in Table 2.4 [5].
`The B-side formulation includes the thickener, low profile additives, and some
`fillers. The A-side formulation also includes low-profile additives (LPA), as
`well as the chemical reaction initiator and inhibitor, wetting agents, and mold
`release. The A and B side formulations are mixed in a predetermined ratio,
`typically in the range of 10/ 1 to 20/1 to form a paste.
`
`
`
`Table 2.4
`
`Inhibitor traces
`Initiator
`
`Wetting agent
`
`Release agent
`Filler
`
`Formulation for a Typical SMC [5]
`
` Weight I3/0
` Ingredient
`
`Weight %
`Ingredient
`
`Polyester resin
`Styrene
`15
`17
`
`
`Styrene
`LPA
`30
`2.0
`
`LPA
`Thickener
`8.0
`14
`
`
`
`
`Color pigment
`Filler
`
`1.0
`46
`
`0.5
`
`1.0
`
`1.5
`
`The compounding of the resin recipe into a paste is performed before it
`reaches the combination line where the SMC sheet is produced. The paste is
`then metered into a Doctor Box where the resin is applied to a polyethylene
`carrier film. At the same time fibers are chopped to lengths of 25 to 50 mm and
`sandwiched between two carrier films to form the SMC sheet. The typical fiber
`content varies between 25 and 40 vol%. The sheet is then compacted to ensure
`the impregnation of the fiber. A schematic of this line is shown in Fig. 2.9. After
`completion the sheet is rolled and stored to mature for a period of 2 to 5 days.
`
`Continuous
`strand roving
`
`
`
`
`Resin/filler
`
`Carrier film
`
`
`Chain link
`compaction belt
`
`
`N t»:
`Chopped
`roving ,_ ELKi J ‘
`L.~ m‘
`
`at attic.
`
`
`
`.-
`.0 o . . u. a
`
`OKQIHIIWI.
`Resin/filler
`
`paste
`Take—up roll
`
`Carrier
`film
`
`Figure 2.9
`
`SMC production line.
`
`MacNeil Exhibit 2077
`
`Yita v. MacNeil IP, |PR2020-01139
`
`Page 11
`
`MacNeil Exhibit 2077
`Yita v. MacNeil IP, IPR2020-01139
`Page 11
`
`

`

`
`
`2.2 Compression Molding Material Preparation 35
`
`The compounding of BMC starts with the production of a paste. The paste is
`prepared by mixing the resin with the different additives. This paste is then
`mixed on a batch mixer with the fillers. After this mixture is homogeneous,
`towards the end of the mixing cycle, fibers are added. A schematic of this
`process is shown in Fig. 2.10. The BMC compound can be further extruded to
`form cylindrical batches to facilitate placing in the compression mold.
`
`Paste
`
`Fibers
`
`U
`
`Batch
`mixer
`
`Extruder
`
`Cutter
`D
`
`[I
`
`BMC roll
`
`Figure 2.10 Schematic of a BMC compounding line.
`
`34
`
`Compression Molding Materials
`
`During the matm‘atitin period the compound thickens. to a moldable
`viscosity. The SMC sheet includes all the components needed for molding‘the
`final part (resin, reinforcement, filler, catalyst, low-profile additives, etc.) in a
`malleable and non—tacky sheet. 'Its characteristics allow it to fill a mold when
`subjected to the molding temperature and pressure.
`
`2.2.5.2 Bulk Molding Compound (BMC)
`
`The advantage .of BMC is in its short fibers that allow the material to be used
`for injection molding as well as for compression molding. However,
`the
`shorter fibers in general give BMC lower mechanical properties.- BMC is
`produced in bulk form or as extrudedcylinders, which elimm-ates theuse of the
`polyethylene carrier film used in SMC. Because BMC has lower reinforcement
`content, higher
`filler
`loadings can be used With a consequent economic
`advantage. Another advantage- is that BMC does not require a maturation stage.
`The most common form of BMC conta