Note: Descriptions are shown in the official language in which they were submitted.
~L~3~3g
C-08~ 0242
P~
D ~
The present invention relates to a polyblend of ABS-
type resins which may be made by the emul~ion route and which
5 demonstrates good low-temperature tensile strength properties
toget}ler with a good balance of other properties. In a heat-
fused form, this polyblend compri es a matrix phase of a
styrene~acr~lonitrile type copolymer in which are distributed
particles of t~o different types of grafted alkadiene rubber.
One such type o~ graft rubber particle comprises relatively
medium si2ed diene rubber particles rather highly grafted with
styrene and acrvlonitrile type monomers; the other such type
comprises relatively large sîzçd diene rubber type particles
~rafted rather lowly with styrene and acrylonitrile type mono-
mers. The rubher particles in this :Last type are in fact com-
posed of stable agglomerates cf relatively small rubber
particles. Both such types of grafted diene rubber particles
are readily produced by emulsion polymerization technology.
'rhe matrix phase can be produced by emulsion, suspension or
mass route~, or combinations therao~.
~ he polyblends of the present invention di~play a
combination of low temperature impact strength and room tempera-
ture tensile strength which i~ far better than the corrésponding
combination of strength displayed by a styrene/acrylonitrile
matrix containing only one of the two ~uch grafted rubber
components individually and in equivalent amounts. Furthermore,
the polyblends of the present invention display such a combina-
tion of strength propertie~ and are considered to be a
synergi~tically effective combination of a particular lowly and
a particular highly grafted ABS-type rubber component in a
~tyrene/acr~lonitrlle type matrix. Nothing in the prior art
teaches or ~ugge~ts such a synergi~tic combination. ~ '
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SUMMARY
rrhe present invention relates to polyblends adapted
to display a combination of low temperature impact strength and
room temperature tensi}e strengthO The polyblends also display,
when heat-fused, relatively high surface gloss. These polyblends
comprise from about 70 to 89 weight per cent styrene/acrylonitrile
with the balance up to 100 weight per cent thereof being a mix-
ture of two clas~es of graft copolymer particles, each class
being dispersed throughout the styrene/acrylonitrile which,
when the polyblends are in a heat-fused form serves as the
matrix phase. The styrene/acrylonitrile has a weight average
molecular weight of from about 75,000 to 300,000, and the weight
ratio of styrene to acrylonitrile in such copolymer ranges from
about 95:5 to 30:70, The weight ratio of the first graft
copolymer to th~ second graft copolymer in a polyblend ranges
from a~out 85:15 to 5:95.
'~he first class of graft copolymer particles is cha-
racterized by having:
(1~ a number average particle size of frnm about
0~03 to 0.6 micron,
~ 2) a substrate elastomer comprising a copolymer of
fro~ about 70 to 98 weight per cent of a conjugatèd alkadiene
with correspondingly ~rom about 30 to ~ weight per cent based
on total substrate elastomer weight of at least one compound
selected from the group consisting of styrene and acrylonitrile,
preferably acrylonitrile.
(3) a superstrate grafted to said substrate elastomer
and comprising polymerized styrene and acrylonitrile in the
weight ratio of from about 95:5 to 30:70, and
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C-08-12-0242 ~ 3~
(4) there being from about 30 to 100 partq by weight
of grafted superstrate for each 100 parts by weight of said
substrate elastomer.
The second class of graft copolymer particles is cha-
racterized by having:
~1) a number average particle size of from about 0.6
to 3.0 micron, and at least half of such particles have a parti-
cle size a~ove about 0.8 micron,
(2) a substrate elastomer comprising homopolyalkadiene,
pre~erably homopolybutadiene,
(3~ a superstrate grafted to said sub~trate elastomer
and comprising polymerized styrene and acrylonitrile in the
weight ratio of from about 95:5 to 30:70,
(4) there being from about 3 to 30 parts by weight of
grafted superstrate for each 100 parts by weight of said substrate
elastomer, and,
(5) said second grat copolym~r particles heing com-
prised of agglomerated grafted subparticles at least 90 weight
per cent of which have particle sizes in the range of from about
0.05 to 0.15 micron,
This pol~blend has a total elastomer content (ungrafted
basis) ranging from about 10 to 30 weight per cent (based on total
polyblend).
FIGURE DESCRIPTION
. .-- . . .
The invention is better illustrated by reference to the
appended drawings wherein:
Figure 1 is a simplified flow sheet illustrating
preparation of the polyblends of this invention.
Figure 2 is a flow sheet i~lustrating in greater
detail one preferred procedure for preparing the polyblends of
the pres~nt invention.
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C-08-12-0242 ~39~9
Figure 3 is an artist's drawing of amicrograph of a
heat-fused polyblend of the present invention.
~ igure 1 is believed to be self-explanatory. In
general~ one prepares the fir~t and the second graft copolymers
separately and then blends same with added styrene/acrylonitrile
copolymer as necessary or desirable to make a polyblend of this
invention. Conventional procedures are used.
Methods for the preparation of first and second graft
copolvmer are well known to the art generally; see, for example,
U.S.P. 3,509,238.
In figure 2 is present a flow sheet illustrating one
procedure suitable for the preparation on a commercial scale of
polyblends of the pre~ent invention. Micron size ranges shown
are weight averages. The designation "A.O." indicates antioxi-
lS dant. The dotted line arrows indicate an optional procedure.Briefly, butadiene (Bd.) is first homopol~merized in emulsion
and then graft polymerized in emulsion with styrene and
acrylonitrile monomexs. Independently, styrene and acrylonitrile
are emulsion copolymerized. This copolymer emulsion and the
graft copolymer emulsion are then blended with an antioxidant
and the solids of the resulting mixed latex recovered by spray
drying or coagulation ~ollowed by a drying operation.
Independently, a butadiene copolymer elastomer with
s~-yrene or acrylonitrile is emulsion polymerized and then grafted
in emulsion with styrene and acrylonitrile monomers. Recovery
with antioxidant by spray drying, or by coagulation followed by
a drying operation, then occurs. A product polyblend is finally
made by blending this last grafted product with the blend earlier
prepared. Added styrene/acrylonitrile copolymer in bead or
pellet form may be added in the product blend,
~o~
C-08-12-0242
InFigure3is illustrated the usual appearance of a
heat-fused section of a polyblend of this invention. The
smaller particles are those of the highly grafted diene copolymer;
the larger particles develop when an emulsion of the graf~ed
homopolybutadiene particles is coagulated and dried, or simply
spray dried directly.
Other conjugated alkadiene besides butadiene may be
employed, such as isoprene, and the like.
~ composition of a matrix phase preferably approxi-
mates the chemical composition of the superstrate of the graftcopolymers so as to obtain matching oE chemical properties.
THE ~TRIX PHASE
Those skilled in the art will appreciate that a matrix
composition may be prepared by any conventional means known to
those skilled in the art, including, for example, emulsion, sus-
pension, and/or mass polymerization. Those skilled in the art
will appreciate that in a polyblend product of this invention,
the matrix phase tyoically may comprise a mixture of different
S/AN type copolymers derived from several source~, including
ungrafted superstrate material from each of the graft components
as well as added matrix copolymer.
THE DI5PERSED P~SE
The dispersed phase graft copolymers may be prepared
by any conventional means known to those skilled in the art.
However, for purposes of the practi~e of the present invention,
it is greatly preferred to produce a dispersed phase by polymer-
izing the superstrate monomers in the presence of a preformed
rubber substrate. In such a prepared graft polymer system, it
is genexally not possible to extract the rubber from the poly-
merized mass with the usual rubber solvents, but some of the
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C-08-12-0242
starting rubber polymer may not be in actual chemical comhination
with ~he superstrate. Also, since 100 per cent grafting effi-
ciency of superstrate monomers to such rubber substrate normally
is approached on1y at weight ratios of monomers to substrate
of below about 0.3sl, at least a portion of the monomers poly-
merized in the presence of the preformed rubber will not chemic-
ally combine therewith so as to provide the graPt copolymer
product. This portion may be increa~ed or decreased depending
upon the ratio of monomers to rubber, the particular monomer
starting formulation, the nature of the rubber, and the conditions
of pol~merization. ~ience, a dispersed phase typically contains
some amount of (relative to the amount of the first composition
described above) a second copolymer of monovinylidene aromatic
; monomer and alkene nitrile monomer~ ~ny of the usual graft
lS polymerization processes may be used to accomplish polymerization
of the ungrafted ~u~erstrate monomers to the substrate, including
ma~s, suspension, and emul~ion, or combination thereof, Such
techniques are ~enerally well known to those skilled in the art.
Although the rubber may contain up to about 2 per cent
of a cross-linking agent, based on the weight of the rubber--
forming monomer or monomers, cross-linking may present problems
in dissolving the rubber in the monomers for the subsequen~
graft polymerization reaction. In addition, excessive cros~-
linking can result in loss of the rubbery characteristics. The
cross-linking agent can be any of the agents con~entionally
amployed for cross-linking diene rubbers, e.g., divinyl benzene,
diallyl maleate, diallyl fumarate, diallyl adipate, allyl
acrylate, allyl methacrylate, dlacrylates, and dimethacrylates
oP polyhydric alcohols, e.g., ethylene glycol dimethacrylate,
etc.
C-08-12-0242 ~3~39
Of the various techniques customarily employed for the
pol~Imerizing of rubber monomers; including mass/ suspension, and
emulsion polymerization, emuision polymerization is preferred
since such will provide the particle size distxibution most
preferred for use in the present invention. Furthermore, emul-
sion polymerization of rubber monomers produces a latex which is
useful as a base for subsequent emulsion polymerization of the
graft copolymer in the preparation of a dispersed phaseO
The graft copol~mers of a dispersed phase may be pre-
pared by polymerizing superstrate monomers in the presence of
the preformed rubber substrate, generally in accordance with
conventional graft polymerization techniques. Although suspen-
sion and mass polymerization techniques may be employed, the
preferred processes use an emulsion technique to obtain the
particle size of not more than about 0.6 microns for the graft
copolymer which is preferred for use in the practice of the
present invention. In such graft polymerization a preformed
rubber substrate generally is dissolved or dispersed in the
monomers and this admixture is polymerized to combine chemically
or graft a portion of the uperstrate monomers upon the rubber
substrate. Depending upon the ratio of monomers to rubber sub-
strate and polymerization conditions, it is possible to produce
both the desired degree of grafting of the superstrate monomers
onto the rubber substrate and the polymerization of ungrafted
matrix copolymer to provide a portion of the matrix at the same
time. The ratio of monomers to rubber charged to the graft
polymerization reaction zone is the primary determinant of the
superstrate: substrate ratio of the resultant graft copolymer,
although conditions of polymerization, rubber chemistry and
particle size, rates of monomer addition, chai~ transfer agents,
etc,, may also exert an effect.
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C-08-12-0242
The catalyst is generally included within the range
of from about 0.001 to 2 0 weight per cent, and preferably from
about 0.005 to 1 D 0 weight per cent of the polymerizable material,
the exact amount depending upon the monomers and the desired
polvmerization cycle.
~ s is well known, it is often desirable to incorporate
molecular weight regulators such as mercaptans, halides and
terpenes in relatively small percentages by weight,on the order
of from about 0.001 to 2.5 per cent by weight of the polymeriza-
ble material. In addition, it may be desirable to includerelatively small amounts of antioxidants or stabilizers, such as
the conventional alkylated phenols, although these may be added
during or after polymerization.
In the emulsion polymerization grafting process, the
monomers and the rubber substrate are emulsified in water by
; use of suitabla emulsifying agents, such as fatty acid soaps,
alkali metal or ammonium soaps of high molecular weight, alkyl
or alkaryl sulfates and sulfonates, mineral acid salts of long
chain aliphatic amines, etcO Emulsifying agents which have
proven particularly advantageous are ammonium oleate, sodium
palmitate, sodium stearate, and other sodium soaps. Generally,
the emulsiyinga~ent is pxovided in amounts of from about 0.1
to 15 parts by weight per 100 parts~y weight of the monomers,
and water is provided in an amount of from about 1 to 4 parts
per part of monomers, and even in larger ratios where greater
dilution is desirable.
If desired, an aqueous latex formed in the emulsion
polymerization of the rubber sub~trate may provide the aqueous
medium onto which the monomers are grafted, with or without the
addition of further emulsiying agents, water, and the like.
However, the rubber may be dis~olved in the monomer8, and the
mixture reemulsified, or a latex thereof may be separately
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C-08-12-0242 ~39~39
prepared r Various water soluble free radical polymerization
initiators are conventionally used for emulsion polymerization
of the rubber monomer, including conventional peroxi/ and azo-
cataly~ts, and the resulting latex may be used as the aqueous
medium in which the graft copolymer monomers are admixed. In
this manner the catalyst for the rubber polymerization may
function in whole or part as the catalyst for the graft polymeri-
zation. However, additional catalysts may be added at the time
of graft polymerization.
Typical emulsion polymerization conditions involve
temperatures in the range of from about 20 to 100 C. with
agitation, and preferably an inert atmosphereO Pressures of
from about 0O07 to 7,03 ~g/cm2 may be employed, and monomers
and/or additional catalysts may be added incrementally or con-
tinuously over a portion of the reaction cycle. Polymerization
is preferabl~ continued until substantially all, that is, more
than 90 per cent, of the monomers have polymerized. The remain-
ing monomers and other volatile components are then distilled
away from the latex, preferably~ which is then de-watered,
washed and dried.
Particle size of the emul~ion latex graft particles
may be varied by seeding, Pmulsiying agent concentration,
agitation, rubber size variation through agglomeration prior to
grafting, coagulation techniques, etc.
The particles 3ize of the ru~ber has an effect upon
the optimum grafting level for a graft copolymer. For example,
a given weight percentage of smaller size rubber particles will
provide considexably higher surface area for grafting than the
equivalent weight or a larger size rubber particle. Accordingly,
the density of grating can be varied depending upon the size
C-08-12-0242 ~39439
of the rubber particle. Generally the smaller particles will
tolerate a hi~her superstrate/substrate ratîo than the larger
size particles.
The particle size of the rubber graft copolymer has a
significant ~ffect upon the gloss and tensile properties of the
product produced hy the processes of this invention. Typically,
the particle size of the graft copolymers used in the practice
of the presen~ invention may be varied in an emulsion before ag-
glomeration from as little as about 0.03 microns to as much as
about 0.6 microns, depending upon the ultimate properties
desired for a given product.
For purposes of determining weight average particle
size, one can prepar~ a dispersion of the graft copolymer par-
ticles and make a photo-micrograph thereof. The size of approxi-
mately 200 to 1,000 particles is then measured and an average
taken thereo, so as to obtain the average particle size based
upon a number average or a weight average. Alternatively, other
techniqu2s of measurement mav be employed, including light
scattering techni~ues, so long as a reasonably close relationship
is established between actual size and the techniques employed.
Although a starting rubber may be cross-linked, this
may present problems from the standpoint of dissolving or dis-
persing the rubber for a suspension polymerization process. How-
ever, for emulsion polymerization processes the rubber desirably
ha~ a significant degree of cross-linking. With respect to the
graft copolymers, however, at least some degree of cross-linking
is inherent during the graft polymerization processes, and this
desirably may be augmented through the addition of cross-linking
agents or control of the polymerization conditions.
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To prepare a dispersed phase, it i~ preferred as a
first step to mix from about 15 to 99 parts by weigh~ (in terms
of solid content) of an alkadiene type rubbery polymer latex
with, correspondingly, from about 3 to 200 parts by weight of
at least one monomer of the monovinylidene aromatic type or the
alkene nitrile type, which is graft polymeriza~le on said rubbery
polymer, and then the resulting mixture is subjected to an
emulsion graft polymerizationO Thereafter the product is separa-
ted and dried before blending to make a polyblend of this inven-
tion.
~1BODIMENTS
The following specific examples are exemplary of theefficacy of the present invention. All parts are parts by weight
unless otherwise indicated~
EX~1PLE 1
PART A
To 100 parts of a latex homopolybutadiene containing
40 per cent rubber solids and approximately 3.0 parts of rubber
reserve ~oap as an emulsifier are added 30 parts water and 15
parts of a 2.0 per cent aqueous solution of potassium persulfate.
rrhe emulsion is heated to 70 C. with stirring and then there is
added thereto over a period of about 1 hour, 21 parts styrene and
~ parts acrylonitrile. The emulsion is held at temperature for
one hour thereafter with stirring, cooled, coagulated, and the
recovered polymer is then washed and dried and is lightly grafted.
The recovered polymer contains graft copolymer par-
ticles of from about 0.6 to 1.5 micron, and at least half of such
particles have a particle size above about 0.8 micron. The
superstrate has a weight ratio of styrene to acrylonitrile of
about 68:32 to 72:28. There are about 21 parts by weight of
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C 08-12-0242
grafted superstrate for each 100 parts by weight of substrate
homopolybutadiene. These graft copolymer particles are com-
prised of subparticles at least 90 weight per cent of which have
particle sizes in the range of from about 0.06 to 0.1 micron.
The amount of ungrafted styrene/acrylonitrile copolymer admixed
with such graft copolymer particles is about 1 to 8 weight per
cent (based on total composition weight), and such copolymer has
a number average molecular weight of about 40,000 and a weight
ratio of styrene to acrylonitrile of about 68:32 to 72:28.
PART ~
Example 1, Part B, lines 35 50, U.S. Patent 3,509,238
is followed to produce highly grafted copolymer p~rticles.
The recovered polymer contains graft copolymer par-
ticles of from about 0.12 to 0.16 micron. The superstrate
grafted to the substrate elastomer comprises polymerized styrene
and acrylonitrile in the weight ratio of about 64:36 to 68:32.
There are about 100 parts by weight of grafted superstrate for
each 100 parts by weight of substrate elastomer. The amount of
ungrafted styrene/acrylonitrile copol~mer admixed with such
graft copolymer particles is about 35 weight per cent (based on
total composition weight), and such copolymer has a number
a~erage molecular weight o~ about 35,000 and a weight ratio of
styrene to acrylonitrile of about 64:36 to 68:32.
PART C
Emulsion polymerized styrene/acrylonitrile copolymer
is prepared conventionally. This copolymer has a weight average
molecular weight of about 200,000 and a weight ratio of ~tyrene
to acrylonitrile of about 68:32 to 72:28.
PART D
A total of 13 parts of Part A product, 38.1 parts of
Part B produc~, and 48.9 parts of Part C product are blended
together to produce a polyblend of this invention which comprisss
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C-08-12-0242
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(on a 100 weight per cent total polyblend basis~ about 57.9
weight per cent of a matrix phase comprising copolymer of styrene
and acrylonitrile having a molecular weigh~ average of about
172,000 and a weight ratio of styrene to acrylonitrile in the
range of from about 64:36 to 72:28, and about 42.1 weight per
cent of a mixture of a first graft copolymer (of Part B above)
and a second graft copolymer (of 2art A above). The first and
second such graft copolymers are dispersed throughout the
styrene/acrylonitrile matrix phase when this polyblend is heat-
fused. The weight ratio of first graft copolymer to second
graft copolymer in this polyblend ranges from about 28:72 to
30:70J This blend has a total rubber con~ent (ungrafted basis)
of about 25 (total blend basis).
This polyblend is found to produce when heat-fused and
extruded excellent drain, waste and vent pipe. This polyblend
displays a low temperature impact strength of about 19.08
Kgcm/cm notch (Izod) at -40~. and a room temperatuxe tensile
strength of about 365.6 Kg/cm2~ This polyblend has excellent
gloss characteristics.
EX~lPLES 2 - 4
_
The procedure of Example 1 is gensrally repeated to
prepare additional polyblends of this invention and such poly-
blends are evaluated. Result~ are summarized in the attached
Table:
-13-
~39~39
O j ~ O O ~ 3 ~ 5 ~ i . ~ ~ ~ 3 ~ a ~
ID r n ~? o I ~t o
N ~ ~ ~ D g ~ g 3 ~ tD
- n
Ul ~ D, O
U~ ~ U~ o
Q ~D ~4 3 ~ V~ I t NU~ ~ N ~ ~D
n ~ ~ e P~ c 1
g ~ g~
O G~ ~
n~ ~ ~ o ,~
n ~ P ~ P
o @
_ ,~ 1
ul ~
w ~ ~ W tV a~ U~ o 1' ~ 1~ Ul o W O ~ ~n Ix
~n ~ o o o
o
W ~ ~I ~ o ~I
~D cr ~ ~ ~ ~I ~n o o ~ o w o ~ X
~D Ul W ~I ~n WO w Ul Wo o W
W ~V UlW ~ C~ 1 0 O~ 9 0
o ~ ~ Vl o o ~ o ~ o o W o 1~ X
W ~ W O o W
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