10 Nylon 6 RIM R. M. HEDRICK, J. D. GABBERT, and M. H. WOHL
Downloaded by UNIV OF MINNESOTA on July 28, 2013 | http://pubs.acs.org Publication Date: January 8, 1985 | doi: 10.1021/bk-1985-0270.ch010
Monsanto Company, St. Louis, MO 63166 The successful utilization of Reaction Injection Molding (RIM) to fabricate complex polyurethane shapes in a single step from relatively low viscosity streams has led to a search for other chemical systems which can be fabricated by the RIM process. The rapid polymerization of molten caprolactam by anionic catalysis has been utilized to develop attractive nylon RIM systems. The incorporation of a rubber segment in the polymer chain allows the fabrication of high impact or even elastomeric nylon parts. The combination of a rubber phase with the high melting (215°C) crystalline nylon phase provides useful properties at low temperatures as well as at elevated temperatures. Equipment is now commercially-available for nylon RIM and while process conditions are different from those required for urethane RIM, cycle times are competitive. No postcure is required. The
success of
search which
for
urethane
other
can yield
Lactams,
reaction
chemistry products
with
with
injection suitable
molding
useful properties
especially caprolactam,
(RIM)
has l e d to
characteristics
for
and good
are potentially
a
RIM
economics.
interesting
candi-
dates. Caprolactam Molten five
minutes
merization brium
is
caprolactam with
is
amount
commercially-available at
low exotherm
essentially of
(approximately
a reasonable p r i c e .
c a n be p o l y m e r i z e d by a n i o n i c to
complete i n
monomer r e m a i n s
catalysis
produce a s o l i d that
time,
part. although
dependent upon the
two p e r c e n t monomer a t
160°C)·
in
The
one to poly-
an
equili-
temperature
No p o s t c u r e
is
necessary. The nylon
product
6,
melting
at
permitted extreme products for
of
the anionic
a crystalline 215°C.
of
tough
on the other
RIM p r o d u c t s ,
excellent
The development o f
the range
through
polymerization
polymer with properties
to
nylon
extreme. block
In
caprolactam
block
products
addition
copolymers has
to
to
copolymers o f f e r
is
properties,
be extended from nylon
engineering-type
these
of
mechanical
soft
improved some
6 on one
elastomeric properties
process
0097-6156/85/0270-0135$07.75/0 © 1985 American Chemical Society
In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.
136
REACTION INJECTION M O L D I N G
a d v a n t a g e s o v e r n y l o n 6 RIM. These advantages i n c l u d e lower mold temperatures, reduced shrinkage i n the mold and perhaps f a s t e r m o l d ing c y c l e s . When c o m p a r e d t o u r e t h a n e R I M s y s t e m s , t h e s e p r o d u c t s o f f a r an improved balance of s t i f f n e s s and toughness, better chemic a l and temperature r e s i s t a n c e , lower t o x i c i t y and simpler p r o c e s s ing requirements.
Anionic Joyce
Polymerization
and R i t t e r
polymerization
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small
amount
(1)
of
of
of
in
Caprolactam
1941
obtained a patent
caprolactam.
sodium or
They
other
alkali
sodium caprolactam and the
rapid,
caprolactam above
form molten
merization amide
to
is
the
the
rapid
are
clearly
product
of
exothermic
The tion
of
in
polymer most
controlling
the to
it
the
for of
reducing
early
the
melt
the
for
polymerization
of
polymer.
the
The
form
poly-
low v i s c o s i t y
a reaction
cyclic
polyamide. a molten
polymer,
polyamide product
injection
molecular weight desired
levels
of
always
a n d was
molding
high
the
the
light
of
later
did ring-opening
the of
nylon not
Figure
1)
In
understood use
in
the
fiber
or
polymer produced
plastic
the
or
Surprisingly,
6 p r e p a r e d by the of
and prepara-
c o n c e n t r a t e d on
polymerization.
knowledge,
polymerization
giving
rise
to
the
1955,
Monsanto
a n i o n i c method sodium
capro-
of
the shown
in
Italian
patent
580069 w h i c h was
H.
K.
(3)
DuPont
Hall
of
a n i s m w h i c h was tested
by
the
polymerization In
not
The
shown
an a c y l a m i n o end group the
absence
Polymerization
stops
amount w h i c h
polymerization occur
which
controls
of
route
with
the
thermal
the
number
1958.
casting
in
the
Figure
results
initiated
initiation chains
The at
in
initiator,
to
very
occurs,
the
of
is
reduced
the
with
to
1.
reaction. an
equili-
condensation
high molecular Below
initiator
caproFigure
termination
and thus
five
chain
no
The
rapid
polymerization
initiated
polymerization.
started
Very
four
amino end group is
mech-
acyllactam
160°C.
temperature. in
(2)
m e c h a n i s m was
resulted
monomer l e v e l of
published
1958.
2 produces a nylon
there
the
28,
acyllactam
impurities,
the
postulated
proposed an i d e n t i c a l
the
which
of
July
acyllactam
a function
this
issued
and without
when
is
r e s e a r c h on
adding a pre-formed
mechanism f o r
lactam polymerization In
the
(see chains
well.
first
December,
not
A two-stage mechanism
sodium caprolactam of
end group
was
nylon
that chain
combinations of
p r o p o s e d m e c h a n i s m was
procedure of
absence
each
anionic polymerization
in
and a s o l i d
that
exploratory
subsequently
containing
the
occur.
This
published
simple
caprolactam
minutes.
1.
of
lactams.
for
Figure
but
mechanism as
as
in
can be p o s t u l a t e d
and one a c y l l a c t a m
Company b e g a n
thermally-initiated
it
occur,
possibility
catalyzed polymerization
cannot
not its
decade
a function
a condensation polymerization
brium
next
the
after
formed had one amino end group
base
was for
concentration.
In only
very
was
application, i.e.,
during
molecular weight
lactam
system
process
work
the
at
to
t e c h n o l o g y was
polymerization
anionic
was
did
of
a
caprolactam
and h i g h m o l e c u l a r weight
qualities
mechanism f o r
interest
moldings,
to
nylon
base c a t a l y z e d
r e a c t i o n of
system.
since
by
in
high molecular weight
this
polymerization desirable
metal
an i s o m e r i z a t i o n
a high viscosity,
Although
(RIM)
200°C to
reaction
on the
d e s c r i b e d the
weight
temperatures
concentration
molecular
In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.
weight.
HEDRICK ET A L .
Nylon 6 RIM
0^ INITIATION
+ lia
137
0 θ
N
{^^
if
/
-
N(CH ) — c—!f
Ν
9
CATALYST REGENERATION
Ό
+ Na
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PROPAGRATION a
/ \
HN(CH Κ - Ν
e/ )
Τι
+ Na Ν
?
©
c
^ v
» H *(CH )-C-N 9
}
9
Na AMIDE ANION
IMIDE POLYMER
AMIDE ANION
IMIDE
N(CH )-Î-f H - 5 9
NYLON 6 Figure 1. Proposed mechanism f o r the p o l y m e r i z a t i o n of c a p r o l a c t a m .
Œ
2 ^ ^ ^ ^ INITIATOR
a
y^^J CATALYST
thermally
initiated
Na( K^ ^-(CH )-C0
anionic
Ο
Caprolactam
F i g u r e 2. Acyllactam i n i t i a t e d caprolactam.
anionic
polymerization
In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.
of
R E A C T I O N INJECTION M O L D I N G
138 A branching product
of
reaction higher
centration. amount ing
addition
equivalent
reaction
molecular range. tne
The
the
and l i n e a r
of
is
a c h i e v e d by
shown i n
neither
a p p r e c i a b l e amine or
patents
were
issued
amine
to
R
Figure
(5)
0
0
II
II
the
The
where
C—N—C
to
3.
react The
anionic
in
the
distribution
a
weight
with acyllactams,
and the
weight product
A number
detail
the
has
of
structural
polymerization
important
an
branch
of
molecular
formulation
most
give
broad molecular
Company w h i c h
for
to
aniline
eliminate
c a r b o x y l end g r o u p s .
Monsanto
use.
chains
such as to
a very
known
stoichiometric
initiators
is
are
of
p r e d i c t e d by a c y l l a c t a m c o n
w i t h a normal
amines
is
initiator
combination than
a primary
polymer
primary
probable reaction
l a c t a m and t h e i r
the
acyllactam appears
control
for
in
weight
can be prepared over
Since
requirements
Downloaded by UNIV OF MINNESOTA on July 28, 2013 | http://pubs.acs.org Publication Date: January 8, 1985 | doi: 10.1021/bk-1985-0270.ch010
to
weights
(4)
results
molecular
structure
of
capro
for
the
R"
R'
I R" cannot
be a hydrogen.
a n d R"
and have the
The
most
structure
commonly-used i n i t i a t o r s
of
an a c y l l a c t a m
combine
R
1
0
ο II
II
R c—* ι Examples
of
this
type
are
a c e t y l c a p r o l a c t a m and a d i p o y l b i s c a p r o -
lactam. A convenient reacting
an
method f o r
isocyanate with
R Ν C 0
Use
of
+ HN
diisocyanate
growing
at
both
which
weight
usually
crosslinked
are
most
sodium
latter
•
allows
product.
in
R N—C—Ν
produces an i n i t i a t o r
ends,
lightly
an i n i t i a t o r
situ
is
>
molecule capable
faster
polymerization
With d i i n i t i a t o r s
due to
a branching
commonly-used c a t a l y s t s
for
the
of
rate
c a n b e made b y r e a c t i n g
for
product
a
is
reaction.
caprolactam
polymerization
c a p r o l a c t a m and c a p r o l a c t a m magnesium b r o m i d e .
catalyst
by
c a p r o l a c t a m monomer.
J
given molecular The
forming the
a Grignard
The
reagent
with
caprolactam. The
anionic
polymerization
depth by W i c h t e r l e of
Macromolecular Chemistry
Nylon The
6 Reactive
use
of
directly the
production
viscosity, was
is
anionic
low
Corporation. the
of
lactams
Prague.
has
been explored
co-workers
at
the
in
great
Institute
(6-8)
Molding
initiated
Polymer
feed
in
polymerization
f r o m c a p r o l a c t a m was
the
of
and Sebenda and t h e i r
large
initial
and the
pieces rate
heat
commercialized in
The
of
of
to
c o m m e r c i a l i z e d In t e c h n o l o g y was since
the
increase
United
monomer
viscosity
polymerization is
Germany by B a y e r .
the
particularly
molten of
produce cast
low.
of
shapes States
useful is
of
the
A similar
(9)
In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.
by for
low
catalyzed system
Downloaded by UNIV OF MINNESOTA on July 28, 2013 | http://pubs.acs.org Publication Date: January 8, 1985 | doi: 10.1021/bk-1985-0270.ch010
HEDRICK ET AL.
Nylon 6 RIM
F i g u r e 3 . Use of a n i l i n e to c o n t r o l m o l e c u l a r weight distribution.
and
In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.
REACTION INJECTION MOLDING
140 The
adaptation of
casting
and r e a c t i o n
undoubtedly here
proceeded at
reports
the
work w i t h which In culate
1962,
low
cost,
forcement
and y i e l d s
to
Downloaded by UNIV OF MINNESOTA on July 28, 2013 | http://pubs.acs.org Publication Date: January 8, 1985 | doi: 10.1021/bk-1985-0270.ch010
silicates, to
dry.
Moisture
disrupts
the
properties silanes,
which
are
severely
such as
s t i l l
nylon
plasticized
destroyed In
I960's
by m o i s t u r e ,
products ment
are
of
which
the into
taining
dispensed
into
mold. the
the
abrasive
than is
to
best
sale
faces, Methods
Since
rein-
high
loading
with
In
order For
the nylon
are
polymer
system
is
or
very
and bonds
completely
and the
mechanical
Functional
provides While
an
the
effective
nylon
matrix
is
not
maintained.
and commercialized for
RIM
as
molding.
this
several
well The
as
properties
was
before
a
product of
the
develop-
d e s i g n e d and
fresh
charge of
c a p r o l a c t a m was
diluting
built
the
slurry
con-
automatically
any remaining
d i d not
was
typical
catalyzed
proceed
until
the
added. in
the
were
the
an
viscosity
small
if
percent
weight.
very or
abrasive
extrusion
c a p r o l a c t a m w e r e pumped the
injection
clay
is
mineral
much
molding.
particles
to
a product,
of
pigmented c h a i r
less
reinforced
e s p e c i a l l y impact in
a c i c u l a r shaped W o l l a s t o n i t e
stiffness
by
Wollastonite
is
molding
Calcined
properties, mineral
60
(Si02) ,
silica
injection
preferred
combination of
to
Although low
and i s
30
quartz
in
the
range of ground
be p o s t - p r o c e s s e d by
The
is
completely
readily
degraded.
polymerization
clay.
in
to it
silica
bond between phases
injection,
is
fibrous
reinforcement,
range of
excessive abrasion.
silica
greater
impact
sometimes
the
strength,
range of
particles with
a
one
consacrifice
strength.
Hundreds for
used
minerals
microns.
tributed of
that
obtained with very two
I.
The
vessel,
slurries
without
to
the
It
than
a polar
as
injection
Vykan.
be t o l e r a t e d
and c a s t
was
is
tailored
holding
and c a l c i n e d
could not
The
6
are
and m o l t e n
were
polymer
for
After
Minerals
resin,
the
mineral
c h a r g e was
useful
obtainable
b a t c h - c a t a l y z e d , degassed and i n j e c t e d
catalyst most
6
Table
sufficiently
(CaSi03> and
the
initiator,
material
The
in
of
i m p i n g e m e n t m i x - h e a d , e q u i p m e n t was
automatically
charge
next
trademark
given
stiffness
surface.
developed
nylon
the
partimineral
coupling agents
long
properties
mineral-reinforced
the
or
triethoxysilane
formulations
under
as
through
mineral-reinforced sold
silane
and s i l i c a t e
Monsanto
is
of
coupling agents.
and i r r e v e r s i b l y
and r e i n f o r c e d
the
that
use
uncoupled reinforcements
3-aminopropyl
bond between the is
to
the
caprolactam.
nylon
mineral
permeates
adhesion
in
particulate
functional
silicate
since
has
presented
particulate
i n c r e a s e of
with
A polyamide such as
a polar
Company
pumpable s l u r r i e s
mineral
organic
progress
i m p a c t much l e s s
with
to
familiar.
such as molten
the
lactams
d o e s h a v e some a d v a n t a g e s .
multiaxial readily
The
Although
the
it
properties
treat
the
effective.
provide
of
commercial products
by Monsanto
polymers.
monomers
reinforced
necessary
well
the
Monsanto
initiated
of
does not
low-viscosity obtain
at
of
companies.
a r e most
reinforcement,
reduces
molding
several
authors
w o r k was
fibrous
anionic polymerization
activities the
reinforcement
reinforcement with
the
injection
by
of
this
sink-marks were
thousands method. or
other
Since
all
surface
developed which
surfaces defects
shells were
could not
compensated for
were
produced
appearance be
sur-
tolerated.
polymerization
In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.
In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.
load
hrs
3
psi
16-19
92-100
10
0.25
0.1-0.8
120
hrs
M-Scale
Hardness
Strain
24
12-14
0.2-018
D-785-65
D-695
Monsanto ll->45
8->45
ft-lbs
%
Monsanto 4-65
4-30
ft-lbs
psi
R-Scale
Rockwell
@ 1%
Compressive
Stress
122°F,
4000
psi,
122°F,
2000 p s i ,
under
Ball
Falling
Deformation
Dart
Falling
Impact
24
D-790 3.3-8
5
10
8-17
Modulus
Flexural
psi
D-790
3
10
9-15
5
10 18-25
Strength
Flexural
Modulus
D-638
Tensile
5-8
D-638
8-17
6.90-8.80
D-638
Procedure
ASTM
6-12
8.50-14.7
8.70^-14.8
H20
3- 7 psi
psi
-1.3%
Fail
%
3
as
Fabricated
Dry,
2- 3
10
Units
M e c h a n i c a l P r o p e r t i e s of Vykan A ( M i n e r a l -- R e i n f o r c e d N y l o n 6 )
Yield
Tensile
Fail
Elongation
Strength
Yield
Tensile
Property
Table I .
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REACTION INJECTION MOLDING
142 shrinkage desks, hundred
for
The process
cycle
three
to
been p u b l i s h e d ,
large
time
for
minutes.
the
of headboards,
produced for
as
individual
four the
production
terminated of
in
thirty-five
a
twelve-
pounds
were
parts.
mineral-reinforced While
technology is
of
1971.
details
of
contained in
properties
by
injection
Block
then
o b t a i n a b l e from
through
reaction
cast mineral-reinforced
R e s e a r c h was
caprolactam
Nylon
of
as
consisting
was
nylon
6
this
casting
system
a number
have
of
(10)
The range
Furniture
Castings
a variety
total was
patents.
Downloaded by UNIV OF MINNESOTA on July 28, 2013 | http://pubs.acs.org Publication Date: January 8, 1985 | doi: 10.1021/bk-1985-0270.ch010
defects.
and luggage racks
room m o t e l .
produced
not
without
and chests
nylon
nylon
directed at
the
6 products
expanding
anionic polymerization
b l o c k copolymers and t h e i r
was
the of
fabrication
molding.
Copolymers
Chemistry Nylon
b l o c k copolymers were
polymerization polymers.
(11)
diisocyanates groups
which
l a c t a m was the
of
basis
The
with polyether
used for
to
of
initiation
the
prepolymers,
initiated
prepared from
glycols,
c a t a l y z e the
from the
of
anionic
polyurethane the
reaction
This
nylon
block copolymers are
capro
research.
from The
is
(12)
stoichiometric
and caprolactam using
described previously.
end
Sodium
copolymer system
6 RIM
formed
preof
contained isocyanate
reaction.
areas
polymeric polyols w h i c h was
synthesized
presence of
caprolactam polymerization.
some c u r r e n t
NYRIM n y l o n mixtures
previously
caprolactam in
poly
acyllactam
reactions
are
as
follows:
A)
Prepolymer
Formation Χ H0~\/0H
+ X +
1
POLYOL
I—C
I NH ( C H ) — C — 0 · ν ν / * 0 — C ( C H ) 2
5
2
POLYETHER POLYESTERAMIDE In which also of
normally functions
acts to is
the
inert
reaction,
as
so The
presence of The
copolymerization
that
multifunctional
for
the
resulting
reaction
occurs
reaction.
or
in
prepolymer
slowly
catalyst
may b e p r e p a r e d i n
solvents,
acyllactam
caprolactam polymerization,
polymeric polyol moeities.
an a l k a l i n e
prepolymer
organic
PREPOLYMER the
initiator
combine the used
by a c y l l a c t a m . in
seconds. of
prepolymer
acyllactam
ated but
the
is
See R e a c t i o n
with heat
excess
termin (13),
completed within
mass
c a p r o l a c t a m as
An
is
or part
in of
the
presence
the
B.
In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.
total
In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.
8.
8 L
Reaction
B.
2
5
— a
Formation.
[
0
- o-\c
POLYETHER
—0 Jb
11
c—C
->
5
PREPOLYMER
POLYAMIDE
1
NH(CH )
2
0
0
2
5
(CH ) — N H ^ C
*
—C(CH ) —NH—C—R—C-j-NF
POLYETHER POLYESTERAMIDE
2
(CH ) —U—0.
L CLJfl —R—C
Copolymer
5
C(CH ) —NH
È-—ij—C—R—C--NH
8
R
^
0
Downloaded by UNIV OF MINNESOTA on July 28, 2013 | http://pubs.acs.org Publication Date: January 8, 1985 | doi: 10.1021/bk-1985-0270.ch010
2
5
C4h N H ( C H ) ( !
CAPROLACTAM
H] Y
0 II
CATALYST
144 In
REACTION INJECTION MOLDING the
anionic
acyllactam the
polymerization
initiates
At
the
same t i m e ,
as
weak
t a m may i n s e r t The
result the
sented
more
equally groups
at
these
would
of
divided so
if
that
ting
structure
used
a method
in
the
block copolymer, from
the
throughout
the
of
w
See
nylon normal
the
ends
of
The
=
n
selective weight
determine
mer.
These parameters
final
resin
copolymer blocks
determine
product.
are
polyol
The
determined in
exercised
the
over
of
the
addition
molecular
final
weight Thus,
weight
alkaline
catalyst
systems
suitable
for
the
reactions.
The
preferred
prepared
reaction
NYRIM c o p o l y m e r s , catalyst
make up
the
Most
a
of
catalyst
Grignard
two
reactive
such as
that
of
nylon
and by the
nylon
percentage
good c o n t r o l of
can be
copolymers.
caprolactam polymeriza-
and
copolymerization
c a p r o l a c t a m magnesium with
is
the block
caprolactam.
used—reactive
bromide, With
prepolymer
polyether
or
hydrocarbon
to
give
polyester
useful
so
individual
weight
for
in
nylon
as
of
sites
the
polyol
final
such
types
transfer
of
the
to
prepoly-
reaction
the
multiple
polyol
resulting
to
streams.
polyols
yield
of
residues.
caprolactam
in
The
blocks
in
or
to
Kurz
dissolved
glycols
polymers.
is
of
alterna-
(14)
are
may b e u s e d
reaction
used
reagent
These
diols
polyols
of
very
two-package system
concentrate.
of
is
condensa-
the
nylon
ratio
of
of
polyol
amount
prepolymer
only
pre-
same for
Kurz.
and p r o p e r t i e s
The
both
the
weight
molecular
polymer.
E.
weight
to
the
curve
resulting
and the
molecular
is
and a c y l l a c t a m
elucidation
degradation
by p o l y o l
molecular
are
J.
polyol
occurred
copolymerization all
molecular
chain.
147.
for
blocks
the
back-
instead
structure
ester
The
are
by
page
by
of
in
The
fully
the
the
A(BA)
prepolymer
2/1).
d e s c r i b e d more
molecular
prepolymer
that polycaprolac-
prepolymer
distribution
b l o c k copolymer and a n a l y z e d
bisacyllactam
the
end groups.
active
the
M /M
the
so
caprolactam polymerization
resulting
(i.e.,
along
sites
b l o c k copolymer or
schematic.
within
is
linkages
transfer
caprolactam available
between
weight
polymers
and
or
points
occur
clearly
tion
tion
ester
an a l t e r n a t i n g
amount
molecular
nylon
the
initiation
acyllactam initiating
The
Downloaded by UNIV OF MINNESOTA on July 28, 2013 | http://pubs.acs.org Publication Date: January 8, 1985 | doi: 10.1021/bk-1985-0270.ch010
is
ABA w h i c h
from
of
form nylon
prepolymer.
bone a c t
of
to
caprolactam polymerization
resins, ester
block copolymers.
polyols
but
may b e u s e d
these
linkages
in
will
not
in
give
polyester
act
a random copolymer
is
obtained.
block copolymers
are
determined
Other
the block co-
as
multiple
to
the
Properties The
properties
greatest which
extent
play
weight,
an
by
in
s e e n when
range
Table the
polyol
are
type
II.
polyol
of The
nylon
to
polyol
polyamide.
type,
and r e a c t a n t
Other
polyol
ratios
factors
molecular
as
well
content glycol
of
is
of
rubber
varied
phase
from
2000-molecular
with
decreased hardness, modulus
b l o c k copolymer p r o p e r t i e s
effect
changes o c c u r r i n g
are
flexural
of
as
the
conditions.
polypropylene
expected phase
role
coupler-activator
A typical
data,
ratio
important
polymerization trated
the
to
60%.
weight
increased polyether
tensile
accompanied by
0
strength,
increases
in
is
illus-
concentration
tear
tensile
For
was soft
is
these
used.
The
block
strength
and
elongation,
In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.
10.
recovery
and Impact
strength
is
an e f f e c t of
small
which i s amounts for
low l e v e l s
combination In better in
that
Downloaded by UNIV OF MINNESOTA on July 28, 2013 | http://pubs.acs.org Publication Date: January 8, 1985 | doi: 10.1021/bk-1985-0270.ch010
decrease
in
tensile
higher
of
as well
polyol,
and high
strength
higher
6 is
impact
end of
through
polyols
strength.
contribute
modulus,
the physical
to a
particularly property
2000 a r e r e q u i r e d ,
improvements as p o l y o l m o l e c u l a r weight Multifunctional
notch
strength.
polyols
at least
in
impact
obtained which has a
and f l e x u r a l
modulus of
Incorporation
as multiaxial
molecular weight
impact
strength.
i n a dramatic decrease
polyol a modified nylon
Molecular weights
level.
erties
Izod
o f h i g h modulus
the lower
the impact
polyol result
increased
of
balance
further
The f i v e - f o l d
reflected in
of
general,
spectrum.
strength.
accompanied by a n e i g h t e e n - f o l d i n c r e a s e i n e l o n g a t i o n —
sensitivity At
145
Nylon 6 RIM
HEDRICK ET A L .
also
is
with
increased
contribute
beyond
to better
prop-
crosslinking.
Table I I .
Effect
o f P o l y o l Content on NBC
Property Dry
as Molded
Percent
Polyol
0
10
20
40
84
83
78
62
37
10,800
7,800
6,400
5 ,300
2,100
% Elongation
30
35
285
490
530
% Recovery
30
30
30
60
80
1, 3 0 0
800
410
220,000
3 1, 0 0 0
Shore
D Hardness
Tensile
Strength
PSI
Tear
60
Strength
Flexural
PLI
1,800
Modulus
PSI
390,000
Notched
280,000
Izod
Impact Ft The
Lbs./In. effects
balance
for
graphically strength ether
0.6 of
polyether
a different in
Figure
content
is
This
impact
Izod
occurs
linear
in
ether,
the impact rate
14% a n d h i g h e r impact
N.B.
strength/stiffness
are
illustrated
and Izod
polyether
N.B.
impact
content.
modulus e x h i b i t s
u p t o 30% p o l y e t h e r .
range.
But in
starting
This
copolymers as well
A t t h e same also
occurring at a
modulus.
Thus,
a much b e t t e r
phenomenon o c c u r s
as other
poly-
a t a b o u t 14% p o l y -
impact
flexural
copolymers have
and s t i f f n e s s .
As
an expected
The i n c r e a s e i s
an increase i n
the decrease
polyether,the
strength
of
increases.
c u r v e shows
nylon block
modulus
flexural
linearly
strength
than
copolymer
Flexural
the low polyether
much h i g h e r of
4.
increased,
time,
5.7
content on the impact polyether
a r e shown a s a f u n c t i o n
decrease.
polyol
1.6
at
balance
with
other
rubber-reinforced
resins.
In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.
146
REACTION INJECTION MOLDING
Structure While
and Morphology
the polyether
and g r e a t e r continue in
to provide
high
phase r e s u l t s
elongation,
crystallinity
polymer melting
points
scanning calorimeter block
(polyether)
a n d a t 45 t o 5 0 ° C
temperatures
216°C
(nylon The
are
6 T ) m
function
of
content
copolymers is
0 to
deflection
in
These
on
-70°C
transitions
occur
content.
Melt-
copolymer to
similar
to,
the t
g
for
pendulum d a t a
o f NBCs
ranging
representing
in
polyether
9 a n d 18%
but not identical
polyether
with nylon
The copolymer c u r v e s
polyether.
changes i n
This
the nylon
(14)
(G*) as a
deflection t
region
g
6,
show
a
becomes
a t 45
to
are not apparent. F r o m t h e same d a t a ,
function
of
temperature
ether
were
nylon
t g a r e more
from
deleted for
37 t o
while which
This
tends
amount
Another ether,
clarity.
clearly
due to n y l o n
In
Figure
is
is
content
regions
becomes
by the nylon
region
which
tration,
nylon
becomes
phase.
elastic
give
for
increased
to
In In
stiffen
of
temperature
to
the
the range
decrease transition.
in
the
polyether the nylon
the polyether
copoly-
0 t o 20% p o l y -
the mid-range of
phase with
to
more
crystallinity
and also rise
and a t higher
the dispersed
acting as crosslinks
is
poly-
p e a k s become more p r o n o u n c e d , these
content.
the continuous
as a
9 a n d 56%
the changes i n morphology o c c u r r i n g
changes i n polyether
nylon
plotted for
6 the damping peaks
As p o l y e t h e r
6 in
amorphous m a t e r i a l
(G") i s
The curves
to broaden the t r a n s i t i o n of
a r e b e c o m i n g more
Heat
6.
shown.
polymers lites
modulus
Figure
may b e e x p l a i n e d i n p a r t
reason
mer w i t h
the loss in
66%, t h e - 6 0 ° C p o l y e t h e r
the change
diffuse. the
a t -60 to
polyether
torsion
a series
The c u r v e s
much more p r o n o u n c e d w h i l e 50°C
resulting
pendulum s t u d i e s
complex modulus
the dashed c u r v e .
at -60°C,
phase
to heat s a g .
65% p o l y e t h e r
from
5 a n d show for
66%.
are quite
shown
curves
Figure
temperature
from
block
strength
blocks
20% p o l y e t h e r .
dynamic modulus
reproduced i n
which
for
6).
range of
from 1 9 5 ° f o r
impact
nylon
resistance
transitions
(nylon
the entire
range
the hard
and t o r s i o n
c o p o l y m e r s show
a l l copolymers f o r
ing
for
and high
linear
nylon
in higher
the high melting
Differential
in
Downloaded by UNIV OF MINNESOTA on July 28, 2013 | http://pubs.acs.org Publication Date: January 8, 1985 | doi: 10.1021/bk-1985-0270.ch010
rubber
tensile
37%, t h e concencrystal-
rubber
phase.
Resistance
Table
III
shows
copolymers modulus range polyol
with
ratio
the effect polyol
at
even though is
contents
- 2 9 ° / 7 0 ° C shows t h e modulus
i n c r e a s e d from
in
on f l e x u r a l
the mid-range
only
slight
modulus
20-40%.
change
shows a n e i g h t e e n - f o l d
over
for
The l o w the p o l y o l
decrease
20-40%.
In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.
as
HEDRICK ET AL.
Nylon 6 RIM
Λ Τ
POLYETHER
^χ_χ_χ_χ_χ_χ_0-0-0-0-Χ-Χ-Χ-Χ-Χ-Χ-0-0-0-0-0-Χ-Χ-Χ-Χ-Χ-Χ-0-0-0-0-Χ-Χ-Χ-Χ-Χ-Χ'^ NYLON BLOCK COPOLYMER SEGMENT
400 ^/^IZOD 300
Downloaded by UNIV OF MINNESOTA on July 28, 2013 | http://pubs.acs.org Publication Date: January 8, 1985 | doi: 10.1021/bk-1985-0270.ch010
i-12 Δ
g
200
V \
FLEXURAL MODULUS
as g
w 100
L
4
1-2 10
20
30
50
40
COPOLYMER % POLYOL
F i g u r e 4 . Modulus-impact balance f o r n y l o n b l o c k (dry-as-molded).
copolymer
9.0
8.0
-100
-50
0
50
100
150
200
Temp. (°C)
Figure 5 .
Dynamic modulus curves f o r n y l o n b l o c k
(complex modulus
^^^ CfliàfCll Society Library 1155 1«h 8t N. w. W a shington. 0. C 20036 In Reaction Injection Molding; Kresta, J.; v e r
copolymer
a
ACS Symposium Series; American Chemical Society: Washington, DC, 1985.
Downloaded by UNIV OF MINNESOTA on July 28, 2013 | http://pubs.acs.org Publication Date: January 8, 1985 | doi: 10.1021/bk-1985-0270.ch010
REACTION INJECTION MOLDING
Figure
6.
Loss
modulus
versus
temperature
for
nylon
block
copolymer.
In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.
10.
Nylon 6 RIM
HEDRICK ET AL.
Table
III.
149
NBC T e m p e r a t u r e - M o d u l u s Polyol
20 Flexural
Downloaded by UNIV OF MINNESOTA on July 28, 2013 | http://pubs.acs.org Publication Date: January 8, 1985 | doi: 10.1021/bk-1985-0270.ch010
Content
35
30
40~
Modulus
@ -20°C
296,000
80,000
54,000
28,000
23°C
197,000
42,000
22,000
11,000
70°C
71,000
21,000
17,000
9,000
Modulus
Ratio
-29 /70°C
4 2
Q
The and
contribution
soft-block to
C as
Even
163
at
quite
to
crystalline
sag e x h i b i t e d
these
very
low
low
heat
which
painting
steel
heat
values end of
are the
sag values
withstand
an a b i l i t y line
the
3^2 high melting
are
also
by NBC.
to
automotive
could
relate
to
assembly
eliminate
the
o p e r a t i o n and permit
IV.
Flexural PSI
.125" Moisture
6
blocks
the
the
heat
modulus.
sag values
were
the
ability
line
paint
requirement
use
of
the
of
fabricated
bake-oven for
cycles—
a separate
same p a i n t s
used
off for
NBC H e a t
Sag/Flexural
Modulus
Modulus
Heat
Sag
163°C
@ 230C
-
0.1
115,000
.06
60,100
0.15
33,500
0.15
24,700
0.2
11,000
0.34
thick
in.
specimen 4"
overhang
-
60
minutes
Effect
effect
of
documented.
moisture (15)
copolymers to
requirements
applications nylon
shows
flexural
spectrum,
169,000
block
IV
the
in
components. Table
The
nylon
reflected
Table
related modulus
3Λ
low. The
parts
the
of
hard-phase separation
sag
at
3^8
1
resistance
of
Response
block
for
on n y l o n
Because of
6 resins
this,
the
is
well-known
susceptibility
moisture
absorption
was
exterior
automotive
body p a n e l s and
requiring
dimensional
copolymer formulations
expected.
and of
wellnylon
Evaluation other
stability
indicated that
would not
meet
early
specifications
In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.
150
REACTION INJECTION M O L D I N G
with in
regard
to
not
sufficient The
in
use
moisture
tion not
creased fiber meet
total
moisture
the
rate give
absorption but
in
of
the
stability
of
of
relative
8.
the
end-use,
60%
the
Figure
9.
of
The
glass
by r e i n f o r c e m e n t
values
appear
applications Molding
parts
our in
resin
purposes,
which
they
two
e.g.,
reaction more
In
ment part, ments
can be
resin
fully
for is
decreased
well. to
The
nylon
6.
The
be s u f f i c i e n t
for
copolymers
30%
improvement
while of the
in
Polyol
C gave
milled
glass
immersion
reinforced reduced
to
glass for
is
humidity
resin
exterior
dimensional
reflects
a maximum
fiber.
fiber
growth of
These automotive
stability.
transfer
the
as
impart
much h i g h e r required
injection
static
set
up
to
low-
d e f i n e d as
are
or
carried
molding,
molding
streams
parts
produce
casting.
are
and i n j e c t e d
RIM
to
can be
rotational is
a
combined and mixed
into
form a p l a s t i c
mold with
molding,
mold and the
impregnate to
are
injection
molding,
device
systems
prepolymers
reaction
rapidly
the
or
a c l o s e d mold
part.
To
foamed to
compensate
some
dynamic mixers
compensate for
degree.
a r e employed
polymerization
additional material.
Thus,
a
produced.
percentages of
In
to
significant
only
relative
in
parameters
reactive
casting,
by p a c k i n g
into
so
to
pumping systems
part
placed
as
three
of
milled
requiring
shrinkage,
low-pressure
shrinkage solid
1/16"
transfer
or
polymerize
polymerization the
as
fiber.
nylon-based polymer
an impingement mixing
In
C not
Improvement
f r o m monomers
processes;
casting,
For
of
directly
several
pressure
where
glass
almost
values
within
glass
insufficient
identical
on the
Expansion
areas
polymerization
finished
process
be w e l l other
is
gave a f u r t h e r
illustrated
25%
with
Β
in
Processes
Anionic by
to or
with
of
A and
stability,
Polyol
with
added
range of
was
absorp
greatly
C)
C gave
C is
fiber.
but
of
NBC f o r m u l a t i o n
The
with Polyol
of
types
Polyols
Reinforcement
conditions
Polyol
improvement.
three
absorption
humidity
the
original
effect
for
copolymer appears to
Figure
of
large
of
effect
orientation
to
rate
in
over
The
dimensional
C c o p o l y m e r was
Under
7
improvement
Use
The
of
6.
copolymer.
well. in
decrease
stability.
absorption,
(Curve
this
The
reinforcement
applications.
expansion.
Polyol
of
degree of
critical
a b s o r b e d , but
reinforcement
and
the
polyol variation
rate
as
fiber
NBC g a v e u n e x p e c t e d i n c r e a s e
Figure
20%
improvement
for
moisture
in
when r e i n f o r c e d
nearly
a
of
further
below,
third
typical
in
nylon
i n c r e a s e d the
expansion
with
of
applications,
shown
0.3%
blocks
that was
dimensional
data
over
absorption.
glass
dimensional
level
absorption most
required
rubber
expansion
of
Polyol
amount
for
polyol
specifications A
the
use
shown
will
decrease
out
give
moisture
the
is
illustrated
Downloaded by UNIV OF MINNESOTA on July 28, 2013 | http://pubs.acs.org Publication Date: January 8, 1985 | doi: 10.1021/bk-1985-0270.ch010
of
from
absorption
blocks.
only
the
to
on l i n e a r
polyol
as
e x p a n s i o n due to
expansion r e s u l t i n g
for
c l o s e d mold which
the
possible
RIM
casting, rotates
or
the
long
short
mat the
fiber to
fiber
is
injected use
so of
reinforce
the
molded
reinforce
processes.
reactant
around
or
is
permits
and toughness
with
casting
the
stream
This
fiber
maximum s t i f f n e s s is
reinforcing
liquid
reinforcement.
heavy continuous
than
rotational
the
a preformed
reacting
one o r
mixture
is
more axes
introduced so
as
to
In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.
into
produce
HEDRICK ET A L .
Nylon 6 RIM
Downloaded by UNIV OF MINNESOTA on July 28, 2013 | http://pubs.acs.org Publication Date: January 8, 1985 | doi: 10.1021/bk-1985-0270.ch010
3.0
5
10
15
20
25
36
Days Water Immersion 72 F F i g u r e 7. copolymer.
Effect
of water immersion on e x p a n s i o n
of n y l o n
In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.
REACTION INJECTION MOLDING
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3.0L
% Relative Figure 8. Effect b l o c k copolymer.
Humidity
of r e l a t i v e h u m i d i t y on e x p a n s i o n of n y l o n
In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.
HEDRICK ET AL.
Nylon 6 RIM
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2.0l
S
10
Days
IS
20
23
Immersion
F i g u r e 9 . E f f e c t of water immersion on r e i n f o r c e d f o r c e d n y l o n b l o c k copolymer ( P o l y o l C ) .
and
unrein-
In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.
154
REACTION INJECTION M O L D I N G
a uniform l a y e r of polymer on the hollow part is produced. The
last
Reaction
important
First,
processes are not
Injection
Nylon-based molding
two
RIM
from urethane
RIM
systems
the
RIM
equipment and
found most
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points
at
heated
tanks,
pumps,
accomplished
or
water
by
urethane
two
not,
streams.
are are of
operating
chemically is
used, that
typically
required
pressure
lines
Third, those
of
versus for very are
gel
5
to
30
temperatures stability.
At
pot
the
life
of
tures
from
typically Thus, the
of
reactants
This of
part
to
of
longer
time
caprolactam,
urethanes.
nylon on is
are
hot
they
contain
of
This
allows
temperatures,
of
45
to
is
the
Second, 90°F
the
lower
order part
of
rate
5-10
surface
are normally temperatures,
seconds for
also 3-4
than
reasons until
reactants the
mold
parts
difference
mold
of
about
is
the
temperature
a result
of
the
low
at
gel
and For
and tempera
times
are
thickness.
reauired
for
by c o n d u c t i v e h e a t i n g . very
Kcai/mole versus exotherm
run
1/8-inch time
is
minutes.
quality
these
is
low-
seconds,
than
molds
only
of
systems.
several
At
to
one-tenth use
monomer
polymerization
on the
generation,
time
is
120
RIM
gel
pressures
hydraulic
nylon
rise
energy
for
and 3 2 5 ° F .
60
streams
a r e much l o n g e r
in
to
normal
since both
There are
30
and
their
required
horsepower
attained.
viscosities
they
This
soluble
the
l a c t a m monomer,
range.
systems
rubber
typical
Carbide,
over
be
spots.
energy c o n s e r v a t i o n and product
A typical reaction
NYRIM 2000 n y l o n
preferred
mixxng n e a d
i.iie o r d e r
temperatures or
the
psig
urethanes.
polymer
mixed stream
the to
of
from Union
Thus,
oil
resistance
are
compared w i t h
in
this
hot
temperature-controlled
Additionally,
and lower
times
tool,
in
practice,
circulating
a comparison of
systems.
typically
these
them have
whether
xmpingemenL
materials
equipment must
methods
solutions
are
making
and l a c k
2700
150-300
the
urethane
reasons
the
30
the
and
these
equipment w i t h two
for
in
the
b e t w e e n 250
10 RIM
low
optimum p h y s i c a l p r o p e r t y release
several
systems
commercial
viscosity
comparable.
held at for
in
are
high molecular weights typically
in
polyol
RIM,
copolymer from Monsanto,
seconds for
First,
In
streams,
and so
for
urethanes,
this.
control
system,
and v a l v e s
rhe
the
of
low
RIM
hardware
first
systems
low
RIM
liquid
equipment w i t h
temperatures.
quite
quite
nylon
Thf
See F i g u r e
n y l o n - b a s e d RIM
mixing
the
reactive
block
nylon the
urethane
and molds.
are very
a t y p i c a l urethane of
Thus,
tracing
uniformity
the
or
in
by e n c l o s i n g the
NYFTM 2 0 0 0 n y l o n in
lines
electrically
Second,
ranges
common u s e
hands and t a p e s . their
for
Unlike
1 5 8 ° F and 3 2 0 ° F r e s p e c t i v e l y ,
by j a c k e t i n g
systems,
modifiers of
in of
useful
lactam.
room t e m p e r a t u r e .
is
design of
conditions.
monomers
solids
A
urethanes.
Impact
isocyanate materials
of
with
cavity,
differ
have m e l t i n g
cause
the
systems
the
or
practiced
of
Molding
ε-caprolactam and l a u r y l
ovens
surface
aspects which
process
heating
inner
is
low
18-20 shown
heat
of
kcal/mole in
Figure
reaction for 11
block copolymer.
In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.
for
H E D R I C K ET A L .
Nylon 6 RIM
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ιο,οοα
Figure
10.
Viscosity
of
urethane
a n d NYRIM
raw m a t e r i a l
streams
In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.
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REACTION INJECTION M O L D I N G
Figure 1 1 . In-mold reactant made from NYRIM 2 0 0 0 .
temperature d u r i n g c u r e of a p a r t
In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.
10.
The in
net
nylon
less
effect
RIM.
part
jection although
is
This as
rates
method of
as
high
foaming.
as
In
tion
systems.
density the also
of
optimum
Blowing
frequently
1.0-1.4
added
to
systems
the
and urethane reactant
in
external
used. lb
In-
parts,
the
systems
streams
tanks
density
the
in
the
typically
b y means o f
microcellular
Freon
is
are
p i p e l i n e mixers
of
such as
control
are
be used and produces
common o n 3 - 4
measure and c o n t r o l
agents,
to
l b s / s e c o n d can be u s e d .
control
to
rates
pumping u n i t s
lb/second are
by f r o t h i n g
gauges are used
tanks.
injection
smaller
between n y l o n
by use
For
lower of
urethanes,
nucleated with nitrogen or
use
0.1
difference
speed a g i t a t o r s
permit
when f i b e r - r e i n f o r c e d
low
as
A fourth
to
permits
anisotropy
rates
157
Nylon 6 RIM
H E D R I C K ET AL.
high-
recircula-
foams, froth
nuclear
density
in
chloro-fluorocarbons, and shrinkage
values
are
of
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urethanes. Nylon
RIM
gen content blanket
used
soluble
in
The
nylon
upon
systems
is to
the
inert
foam i s
throttling
the
and
material
produced
as
hold
The
fact
no
is
comes
out
RIM
have a l s o
in
Chemical
been
is
quite
required.
the
reactants
and
the
streams
nitro-
is
orifices
the
simpler.
of
of
nitrogen
Nitrogen
soluble
nylon
the
frothing
much l e s s
that
control
of
tanks.
impingement mixer
nitrogen
but
pressure
by gas which
the
nucleating agents
Accurate target ties,
in
only
to
blend of
achieve
during
polymer
are
than
liquids,
blowing
successfully
rate,
not
that
ratio
either
kinetics
Internal
not
agents
used
in
nylon
require
a p p l i c a t i o n of
urethane
the
urethane
build-up tating
in use
every
reactant
head.
mold,
urethane release internal
third
Newer shots
spray
to to
high
as
The
All
Nylon
affect
show
the
determined the
stream
systems
proper-
of
contains
will
well.
of
physical
second
5% d o n o t
for
a mold r e l e a s e streams
or
These
agent,
to
the
tanks
reactions
even with
internal
well
contains
only
can be
formu-
any e f f e c t
developed
urethanes.
on
the
because
mold r e l e a s e
quality
tool. that smooth
Monsanto's is
RIM
a
react
to
with
problems
of
necessiSome
newer
introduce mold r e l e a s e at systems nylon
paintable.
show
they
have caused
permit
b e made b e t w e e n a p p l i c a t i o n s o f the
a soap or
mold s u r f a c e s .
to
nylon
urethanes
cannot be added
spray-on mold r e l e a s e s ,
scrub
for
Most
a wax,
Many m o l d r e l e a s e s
component stream
mold r e l e a s e
a high
stream which
technology is
shot.
chemicals.
a
the
being developed
p e r i o d i c shutdowns
systems
where
is
the
part
as
0.5%
essentially
being o f f - r a t i o
as
systems
within
properties.
mold r e l e a s e
after
in
are
components.
Thus,
changes
while
the
materials
made
to
finished
nylon
RIM
nylon
isocyanate ratio.
physical properties.
or
it
desired
modifier
systems
silicone,
the
with
be h e l d
to
solution.
lated
important
typically
sensitive
materials
reaction so
of
and rubber
catalyst
less
must
being very
properties
initiator
is
ratios
order
these
the
metering
stream
physical
mix
the
systems.
Urethane
by
nitrogen-blown
makes a c c u r a t e m e t e r i n g
solid
RIM
the
through
monomer.
froths,
also
c a p r o l a c t a m monomer a n d s o
polymerization, in
are
p r o v i d e d by s e t t i n g
surface
In is
RIM
from
external system
certain required
0
to
the
50
mold
contains
an
applications on a p a r t ,
In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.
a
158
REACTION INJECTION M O L D I N G
thermosetting the
reverse
tial
release
part
to
face
quality
result
systems
from
the
tool
of
in
lies
surface, of
then
in
tool.
the
extent
of
reacts are
The
state
with
fully of
the
allowing tool
the
urethane breaks
tool
after
each
comes
out
between urethane are
quite
used for
shots,
urethane
similar surface
the
RIM.
results off
shot. need
means t h a t in
be u s e d . RIM
mold.
Many
mold to
generate
the
part.
reaction before the in
Parts
atmospheric
part.
Nylon for
cycle
spite
of
Nylon
RIM
which
is
be manually flash
the
is
much
part.
This
mold r e l e a s e a p p l i c a t i o n times
the
Commercial
flash
and must
completely with
and the
comparable,
the
sur-
A
may a l s o
the
of
reverse
and n y l o n
isocyanate in
the
from
surface
mold.
which
and t y p i c a l l y
operation,
lower
enough i n
produces differen-
maximizing
replication.
a 5°F
complete the
tougher
in
show
demolding and h a n d l i n g
removed
difference
the
the
mold r e l e a s e s
far
that
provides
surface,
between urethane
residual
cure of
surface
This
cure obtained in
for
cured in
weak a n d b r i t t l e ,
tool
surface
Silicone
difference
green-strength
parts
fairly
the major
oven post-cured to
moisture
time
the part.
the
tool
are polymerized just
sufficient
parts
the
adhere to
and f i d e l i t y
last
urethanes
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u s e d on
can be o b t a i n e d by m a i n t a i n i n g
The
RIM
is
unseen surface
preferentially
temperature
are
mold r e l e a s e
or
for
nylon
and
urethane
shorter closed-mold
cycles
of
2.5
minutes
are
common. Equipment As
Requirements
a result
machines
of
the
system
can be simpler
The
nylon machines, of
insulated,
but
tion
and have l e s s
rates The
tionally, lids
they
tanks
anchor-type valve
differences
and lower
for
the
need
if
should
any
should
be h e a t e d to
which might
plug
pressure and l i d
ethylene-propylene should
be both
The This
avoids
should
clean
out.
to
and
and l i n e s of
where
flexible
are
jacketed,
it
preferred
side
Should
streams, the
oil
nylon
then than
RIM
ers
of
RIM
for
nylon
of
the
it
is
visa
reaction
be set
occur more
versa. speed
of
of
to
avoid
occur.
Tank
l a c t a m monomer
Teflon the
resin
or
monomer.
to
allow
material when
Tanks
that
the
jackets
oil
pumps
that
to
jacket
the
stainless
Where
these
the
to
oil
will
lines the pressures
leak
into
affect
Many m a n u f a c t u r -
valves
steel.
Teflon
reactant
adversely
and p h y s i c a l p r o p e r t i e s .
m a c h i n e s b e made o f
with
keep
and All
machine
lined
and the
reactants
tanks,
lines
be coupled
contamination w i l l all
the
are used.
simplify
required.
likely Oil
to
hoses
are
between the
recirculation. in
they
lines
equipment recommend t h a t RIM
up
the
materials
recirculating
leakage
type
speed
Addi-
pressurization/degassing
be s e l f - d r a i n i n g
preferred
low.
slow
be u s e d .
flush
be of
surfaced flexible
are
suction
or
injec-
vacuum-capable.
be d e s i g n e d to
is
valves
control
inside
to
reinforcement
a v o i d a t t a c k by
reinforcing
Smooth
are
the
RIM
control.
be a g i t a t e d w i t h
be of
should
should
temperature
settling
lines
rubber
pressure
tanks
improves
relief
have lower
ratio
avoid sublimation
seals
nylon
heated and
units,
systems of
outlined,
urethane machines.
be w e l l
accurate
settling
also
Agitator
for
reinforced
bottom v a l v e s
than
pressure
nylon machines should
should
ports.
previously cost
c o u r s e , must
can be lower
agitators
plugging
in
and
Mild
fittings steel
In Reaction Injection Molding; Kresta, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.
and
10.
HEDRICK ET AL.
galvanized
Nylon 6 RIM
steel
tanks
have been
copper
and brass
lines
and f i t t i n g s
of
the
material
mately
painted.
was
Both rotary for
nylon
forced
not
an i s s u e
Tank
b e made with
the
however,
parts
metering
piston
to
be
volumes
of
nitrogen
is
gas
were
units
units
have
color
be
u l t i -
to
are
are
as
the
suitable
best
for
rein-
the
in
the
tank
Molds
for
nylon
materials
plating
resistance
of
epoxy
a few
is
parts
30
psig
mix
incorporation
tanks
adjusted
of
of
all
less
storage
than
are used,
also
before
tends
and
5 ppm
is
depending upon
of
used
failing.
large
dissolved pressure.
improve At
that
variety
and n i c k e l .
to
materials.
demonstrated
the
from a wide
kirksite
been widely
fiberglass
carry
nitrogen
c a n b e made
softer
when
to
degassing,
aluminum,
been
required
by c o n t r o l
systems
steel,
has
is
Following
made o f
system
to
the
RIM
has
molds
tooling
0
inerting
content
its mix.
including
and n i c k e l
gas
produced.
used as
into
dry
from
Vacuum d e g a s s i n g o f reinforcement
for
a moisture
pressures
foam d e n s i t y
than
used,
a p p l i c a t i o n s where
because
Displacement lance
Nitrogen
suitable.
of
in
systems.
tanks.
the
successfully
pump a n d p i s t o n - t y p e
RIM.
P r o v i s i o n must hold
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159
this
will
Development work
Chrome
the
scratch
writing,
produce
no
more
continues
in
this
area. In used
most
for
lines
should
done a t means or
respects,
urethanes. be