METHOD OF PREPARING THERMOPLASTIC RESIN COMPOSITION HAVING SUPERIOR SURFACE CLEARNESS AND GLOSS
[Technical Field]
The present invention relates to a method.of preparing a thermoplastic resin composition having superior surface clearness and gloss. More particularly, the present invention relates to a method of preparing a superior tnermoplastic resin composition which has superior surface
clearness and gloss and may prevent mold deposition during a high speed injection process, by using a reactive emulsifier during emulsion polymerization of rubber latex composed of
polybutadiene, preparing resin latex using a hydrophobic initiator during graft copolymerization of rubber latex, an aromatic vinyl monomer, and a vinyl cyan monomer,
compression .dehydrating a moisture content to less than 10% using a compression type dehydrator after agglomerating the resin latex, and performing a wet powder extrusion process.
[Background Art]
An acrylonitrile-butadiene-styrene copolymer resin
(hereinafter, referred to as "ABS resin") has superior
mechanical properties and chemical resistance, and exhibits
25 excellent colorability, machinability, and the like.
Accordingly, the acrylonitrile-butadiene-styrene copolymer
& .
resin is broadly used in interior and exterior components of
electrical and electronic products, vehicles, small toys,
furniture, construction materials, and the like. A method of
preparing an ABS resin comprises emulsion polymerizing a
5 butcldiene murlurrker to prepare polr9outadiene rubber latex,
graft copolymerizing the polybutadiene rubber latex with an
aromatic vinyl monomer and a vinyl cyan monomer to prepare
resin latex, dehydrating the resin latex using. a dehydrator
after agglomerating the resin latex, and drying the
10 dehydrated resin latex using a dryer, thereby obtaining an
ABS resin having a general pellet type. The obtained pellettyped
ABS resin is generally processed into a desired type
by extruding and/or injection molding with styrenea&
rylonitrile copolymer resin (hereinafter, referred to as
15 "SAN resinN) prepared through solution polymerization.
However, in most methods of preparing an ABS resin,
emulsion polymerization using a general emulsi'fier such as
rosin, fat, or the like is employed. Accordi.ngly, after
polymerization, impurities such as an emulsifier, an
20 electrolyte, and the like, and monomer remainders remain,
and, as such, surface clearness and gloss are limited due to
gas generation during a high speed injection process and
there are problems such as mold deposition and the like.
Therefore, to improve the problems, a method of
25 preparing an ABS resin using a mass polymerization method is
partially used. However, an ABS resin by mass
,A .,
polymerization exhibits reduced gloss and has limitations on
obtaining a high-impact thermoplastic resin.
Recently, there are intense efforts to improve quality
of household appliances such as smart TVs, air conditioners,
5 and the like, and diversify designs thereof. Development of
materials corresponding to such efforts is urgently
required. In addition, development of materials having
superior thermal stability and not exhibiting mold
deposition, during an injection process and .a high-speed
I I 1 10 injection process for mass production, is required.
I . Furthermore, development of environmentally friendly low
emission materials is required.
15 Therefore, the present invention has been made in view
of the above problems, and it is one object of the present
invention to provide a method of preparing a thermoplastic
resin composition having superior surface clearness and not
exhibiting mold deposition by polymerizing with. a reactive
20 emulsifier, instead of rosin or a fat emulsifier, during
preparation of polybutadiene rubber latex through emulsion
polymerization and graft copolymerization of the
polybutadiene rubber latex, an aromatic vinyl monomer, and a
vinyl cyan monomer, to prevent gen'eration of a small amount
25 of gas and remove factors causing mold deposition,
particularly during extrusion and/or injection molding, at
clearness and mold deposition mainly occur by using rosin or
a fat emulsifier.
It is another object of the present invention to
5 provide a Iilethod of preparing a thermoplastic resin
composition which may prevent rubber distortion due to high
shear during a high speed injection process by inducinq
inner grafting (the aromatic vinyl monomer and the vinyl
cyan monomer are swelled into the polybutadiene rubber latex
10 and thereby being grafted) of large amounts of. the aromatic
I vinyl monomer and the vinyl cyan monomer into the
I
I polybutadiene rubber latex in a large amount through use of
a hydrophobic initiator during the graft copolymerization
and has superior injection residence gloss.
15 It is another object of the present. invention to
provide a method of preparing' a thermoplastic resin
composition which may minimize contents of impurities
reducing thermal stability of a finally obtained resin by
lowering a moisture content of wet powder to less than 10%
20 using a compression type dehydrator during dehydration to
increase. a dehydration ratio after agglomerating the
obtained graft copolymerized latex and thereby maximally
emitting impurities of the resin latex with water during
dehydration.
25 It is yet another object of' the present invention to
provide a method of preparing a thermoplastic resin
h -
composition which may minimize impurities related to surface
clearness, thermal stability, or mold deposition hy applying
a wet powder extrusion process during an extrusion process
when the wet powder of the resin latex having a moisture
5 content of less than 10% is extruded and kneaded with
styrene-acrylonitrile copolymer resin prepared through mass
polymerization or solution 'polymerization, so as to remove
unreacted monomers, oligomers, an.d the like as azeotropy
with' water when water is volatilized due to vacuum added
10 during wet powder extrusion.
[~echnical solution]
In accordance with one aspect of the present
invention, provided is a method of preparing a thermoplastic
resin composition comprising (1) preparing rubber latex from
15 conjugated diene monomers using a reactive emulsifier; (2)
graft copolymerizing an aromatic vinyl monomer and a vinyl
cyan monomer with the rubber latex to prepare graft resin
latex using a hydrophobic initiator; (3) dehydrating after
agglomerating the graft resin latex to obtain wet powder;
20 and (4) preparing an extruded material through wet powder
extrusion of the wet powder with an aromatic.viny1-vinyl
cyan copolymer.
As one embodiment, in step ( 2 ) , a reactive emulsifier
may be used during the graft copolymerization.
25 As one embodiment, in step (3), the dehydration may be
carried out ,through a compression type dehydration method.
the wet powder may be 2 to 15 wt%.
As one embodiment, in step (4), the, wet powder
I extrusion may be carried out under a vacuum condition of 1
5 to 760 torr.
As one embodiment, the wet powder extrusion may be
I carried out under a vacuum suction condition of 1 to 760
torr.
As one embodiment, . in step ( 4 ) , the wet powder
10 extrusion may comprise a water evaporation process.
As one embodiment, in the wet powder extrusion of step
(4), the aromatic-vinyl cyan copolymer may be. added after
!
adding the wet powder.
As one embodiment, the wet powder extrusion of step
15 (4) may be continuously carried out without a dry process
after the dehydration of step (3).
In accordance with another aspect of the present
invention, provided is a .thermoplastic resin composition
prepared according to the method of preparing the
20 thermoplastic resin composition.
In addition, the method of preparing the thermoplastic
resin composition having superior surface clearness and
superior. gloss according to the present' invention may
comprise (1) preparing the rubber latex from the conjugated
25 dlene monomers using the reactive emulsifier; (2) preparing
the resin latex by graft copolymerizing the aromatic vinyl
_ _ ._- - - -c - - - - < - -
- -~~~Iiil**p-ps-@-lz- I .&$-&-- " 5 - " kc,!? " 3"
% 4.. 59 Ji -
-
- --
I I I' monomer and the vinyl cyan monomer with the rubber latex
usin'g the reactive emulsifier and the hydrophobic initiator;
I (3) dehydrating to obtain the wet powder having a moisture
I
I content of 2 to 15wt% through mechanical dehydration, after
5 agglomerating the resir1 latex; and (4) wet powder extruding
the wet powder with the aromatic vinyl-vinyl cyan copolymer
to prepare a pellet.
In addition, the method of preparing the thermoplastic
resin composition having superior surface clearness and
10 superior gloss according to the present invention may
comprises (1) preparing rubber latex using 1.0 to 3.0 parts
by weight of the reactive emulsifier based on 100 parts by
weight of the conjugated diene monomers; 42) emulsion
polymerizing a reaction mixture obtained by mixing 18 to 40
15 wt% of the aromatic vinyl monomer, 8 to 18 wt% of the vinyl
cyan monomer, 0.1 to 0.7 wt% of the reactive emulsifier, 0.1
to 0.4 wt% of the hydrophobic initiator, and the remainder
of the obtained rubber latex to prepare graft copolymer
resin latex; (3) dehydrating such that a moisture content of
20 the resin latex reaches 2 to 15wt% after agglomerating the
resin latex to obtain wet powder; and (4) wet powder
extruding such that a rubber content in a final resin is 10
to 30 wt% when the wet powder is extruded with the aromatic
vinyl-vinyl cyan copolymer.
25 The reactive emulsifier may be a reactive emulsifier - .
selected from the group consisting of an anionic and neutral
-- - - .* *....,-
-kw?j~z+&.~ >- g/g 1 *%= 13- 3 - &, $9 & 5
)-,
I
polymer-type emulsifier having an ally1 group, an anionic
and neutral polymer-type emulsifier havinq a (meta)acryloyl
group, an anionic or neutral polymer-type emulsifier having
1 a propenyl group, and mixtures thereof.
1 5 In the step of preparing the rubber latex, a gel
1 content control agent may be further comprised in an amount
~ I of 0.1 to 1.0 parts by weight.
The gel content control agent may be selected from the
group consisting of ethyl-2-mercaptoethylpropionate, 2-
10 mercaptoethylpropionate, 2-mercaptoethanol, mercaptoacetic
acid, n-octylmercaptan, n-dodecylmercaptan, tdodecylmercaptan
and mixtures thereof.
The conjugated diene monomer may be selected from the
group consisting of 1,3-butadiene, isoprene, chloroprene,
15 piperylene and mixtures thereof.
The rubber latex may have a swelling index of 5 to 25.
The rubber latex may have an average particle diameter
The rubber latex may have a gel content of 70 to 95%.
20 In the step of preparing the resin latex, a molecular
weight control agent may be further comprised in an amount
of 0.1 to 0.4 wt%.
T.he molecular weight control agent used in the step of
preparing the resin latex may be selected from the group
25 consisting . of ethyl-2-mercaptoethylpropionate, 2-
mercaptoethylpropionate, 2-mercaptoethanol, mercaptoacetic
>
.P - .
I acid, n-octylmercaptan, n-dodecylmercaptan,
I dodecylmercaptan, and mixtures thereof.
The .aromatic vinyl monomer used in the step of
preparing the resin latex may be selected from the group
5 consistii-~g oL styrene, u -methyl styrene, p-methyl styrene,
vinyltoluene, t-butyl styrene, chlorostyrene, substituents
I thereof, and mixtures thereof.
1 The vinyl cyan monomer used in the step of preparing
I the resin latex may be selected from the group consisting of
10 acrylonitrile, methacrylonitrile, substituents thereof, and
mixtures thereof.
The .hydrophobic initiator used in the step of
preparing the resin latex may be cumene hydroperoxide,
diisopropylbenzene hydroperoxide, tert-butyl hydroperoxide,
15 para methane hydroperoxide, or benzoyl peroxide as a fatsoluble
peroxide initiator; a metal salt selected from the
group consisting of metal salts such as iron (n), iron (m),
cobalt (n), cerium ( I V ) , and mixtures thereof, as an
oxidation-reduction system .polymerization initiator; or a
20 reductant selected from the group consisting of reductants
such. as dextrose, glucose, fructose, dihydroxyacetone,
polyamine, and mixtures thereof.
A weight average molecular weight of the resin latex
may be 50,000 to 150,000.
25 The resin latex agglomerated .as described above may be
obtained in a wet powder type, in which a moisture content
pis
2 to 15 wt%, preferably 2 to 12 wt%, more preferably 5 to
10 wt%, through mechanical dehydration. Within this moisture
content range, unreacted monomers, oligomers, and the like
may .be effectively removed as azeot.rope3 with water.
5 The dehydration may be carried out by mechanically
applying pressure. Preferably, the dehydration may be
carried out by again deliydrating using a compression type
dehydrator after dehydrating using a centrifugal dehydrator.
The wet powder extrusion may be carried out by co-
10 extruding the wet powder of the resin latex and the aromatic
vinyl-vinyl cyan copolymer .while applying vacuum to reduce
pressure in a co-extruder to atmospheric pressure or less.
In the wet powder extrusion, addition of the aromatic
vinyl-vinyl cyan copolymer is carried out after adding the
.I5 wet powder of the resin latex to the co-extruder. In this
regard, co-extrusion of the wet powder of the resin latex
and the aromatic vinyl-vinyl cyan copolymer may be carried . m
out while applying vacuum to reduce pressure in the coextruder
to atmospheric pressure or less before and after
20 addition of the aromatic vinyl-vinyl cyan copolymer.
[~dvantageous ef fectsl
As. apparent from the fore-going, the present invention
advantageously provides a method of preparing a superior
thermoplastic resin composition which has superior surface
25 clearness and superior gloss and may prevent mold deposition
during a high speed injection proc&ss, by using a reactive
,J- -.
i emulsifier during emulsion polymerization of rubber latex
composed of polybutadiene, preparing resin latex using a
hydrophobic initiator during graft copolymerization of
rubber latex, an aromatic vinyl monomer, and a vinyl cyan
5 i ~ ~ u ~ ~ u ' ~cor m~perre,s sion dehydrating a moisture content to less
than 10% using a compression type dehydrator after
agglomerating the resin latex, and performing .a wet powder
extrusion process.
[~est model
10 Hereinafter, the present invention will be described
in detail.
A method of preparing a thermoplastic resin
composition having superior surface clearness and superior
gloss according to the present invention may comprise (1)
15 preparing the rubber latex from the conjugated diene
monomers using the reactive emulsifier; (2) preparing the
resin latex by graft copolymerizing the aromatic vinyl
monomer .and the vinyl cyan monomer with the rubber latex
using the reactive emulsifier and the hydrophobic initiator;
20 ( 3 ) dehydrating to obtain the wet powder having a moisture
content of 2 to 15wt% through mechanical dehydration, after
agglomerating the resin latex; and' (4 ) wet powder extruding
the wet powder with the aromatic vinyl-vinyl cyan copolymer
to prepare a pellet.
25 More particulirly, the method of preparing the
thermoplastic resin composition having superior surface
yp-,
i clearness and superior gloss according to the present
invention may comprise (1) preparing rubber latex using 1.0
to 3.0 parts by weight of the reactive emulsifier based on
100 parts by weight of the conjugated diene monomers; (2)
5 emulsion polymerizing a reaction mixture obtained by mixing
18 to 40 wt% of the aromatic vinyl monomer, 8 to 18 wt% of
the vinyl cyan monomer, 0.1 to 0.7 wt% of the reactive
emulsifier, 0.1 to 0:4 wt% of the hydrophobic initiator, and
the remainder of the obtained rubber latex to prepare graft
10 copolymer resin latex; (3) mechanically dehydrating such
that a moisture content of the resin latex reaches 2 to
15wt% after agglomerating the resin latex to obtain wet
powder; and (4) wet powder extruding such that a rubber
content in a final resin is- 10 to 30 wt% when the wet powder
15 is extruded with the aromatic vinyl-vinyl cyan copolymer.
The reactive emulsifier may be a reactive emulsifier
selected from the group consisting of an anionic and neutral
polymer-type emulsifier having an allyl group,. an anionic
and neutral polymer-type emulsifier having a (meta)acryloyl
20 group, an anionic or neutral polymer-type emulsifier having
a propenyl group, and mixtures thereof. The reactive
emulsifier used in the present the present invention
indicates an emulsifier having ability to chemically bind
through polymerization.
25 As anionic emulsifiers having an ally1 group, there
are a sulfate salt of polyoxyethylene aliyl glycidyl
nonylphenyl ether. Meanwhile, as neutral emulsifi'ers having
an ally1 group, there are polyoxyethylene allyl glycidyl
nonylphenyl ether and the like. As a sulfate salt of the
polyoxyethylene allyl glycidyl nonylphenyl ether, ADEKARIA
5 SOAP SE available from Asahi Denka in Japan may be used. In
addition, as the polyoxyethylene allyl glycidyl nonylphenyl
ether, ADEKARIA SOAP NE available from Asahi Denka in Japan
may be used.
As an anionic emulsifier having a (meta)acryloyl
10 group, there is ELEMINOL RS available from Sanyo Kasei in
Japan. AS a. neutral emulsifier, there is RMA-560 available
from Nippon Surfactant in Japan. As a polymer type
emulsifier, there are UM and UX available from Toagosei in
Japan. As a representative example of anionic emulsifiers
15 having a pr'openyl group, there is an ammonium sulfate salt
of polyoxyethylene allyl glycidyl nonyl propenyl phenyl
ether. AQUARON HS produced by Daiichi Kogyo Seiyaku of Japan
and LATEMUL produced by Kao of Japan, and AQUARON BC
produced by Daiichi Kogyo Seiyaku, of Japan as a neutral
20 emulsifier 'are commercially available. As the reactive
emulsifier, an anionic emulsifier is preferable. Neutral
emulsifiers extend reaction time due to poor particle
generation thereof and have lower stability than anionic
emul.sifiers, thereby causing coagulum. The reactive
25 emulsifier may be used alone or as a mixture of two types or
more.
8'- -.
The reactive emulsifier, for example, may be selected
from the group consisting of sulfoethyl methacrylate (SEMI,
2-acrylamido-2-methylpropane sulfonic acid (AMPS), sodium
styrene sulfonate (NaSS) , sodium dodecyl ally1
5 sulfosuccinate (T'REM LF-40, trade name), a copolymer of
styrene and sodium dodecyl ally1 sulfosuccinate,
polyoxyethylene alkylphenyl ether ammonium sulfate (HITENOLBC
and HITENOL-KH, a C16-18 alkenyl succinic acid dipotassium
salt (Latemul ASK and ELOPLA AS100 series, trade
10 names), sodium methallyl sulfonate (SMAS), and mixtures
thereof.
In the step of preparing the rubber latex, the
reactive emulsifier may be used in an amount of 1.0 to 3.0
parts by weight, preferably '1.0 to 2.0 parts by weight, more
15 preferably 1.2 to 1.8 parts by weight, based on 100 parts by
weig'ht of the conjugated diene monomers. When the reactive
emulsifier is used in an amount within the ranges, a
thermoplastic resin having superior surface clearness and
not exhibiting mold deposition may be suitably obtained.
20 The step of preparing the rubber latex may be carried
out by performing polymerization for 5 to 15 hours after
simultaneously adding 50 to 100 parts by weight, out of 100
parts by weight of the conjugated diene monomer before
polymerization initiation, .and then by polymerizing for 10
25 to 20 hours after the remainder of the conjugated diene
monomer simultaneously or sequentially. Here, the reactive
'y -
emulsifier is added at an initial reaction step to improve
stability of the rubber latex and the total use amount of
the reactive emulsifier is preferably 2.0 parts by weight or
less. As the reactive emulsifier, an anionic reactive
5 er~~ulsifieri s preferable. When the conjugated diene monomer
. .
is added during reaction, the reactive emulsifier may be I
added alone or by mixing with a. non-reactive emulsifier.
Rubber latex generated as described above has minimized
remaining impurities, thereby providing superior surface
10 clearness and gloss when an ABS resin is applied. thereto.
In the step of preparing the rubber latex, a gel I
content control agent is comprised in an amount of 0.1 to
1.0 parts by weight, preferably 0.1 to 0.6 parts by weight,
more preferably 0.2 to 0.4 parts by weight, based on 100
15 parts by weight of the conjugated diene monomers, to obtain
rubber latex having an average par'ticle diameter of 2500 to
3800 A and a gel content of 70 to 95%. The gel content !
control agent is preferably a mercaptan and may be selected
from the group consisting of ethyl-2-
20 mercaptoethylpropionate, 2-mercaptoethylpropionate, 2-
mercaptoethanol, mercaptoacetic acid, n-octylmercaptan, ndodecylmercaptan,
t-dodecylmercaptan, which have superior
volatility, and mixtures thereof.
The conjugated diene monomer may be selected from the
25 group consisting of 1,3-butadiene, isoprene, chloroprene,
piperylene, and mixtures thereof. The conjugated diene
monomer may be used with an ethylene unsaturated monomer.
The unsaturated monomer may be selected from the qroup
consisting of preferably an aromatic vinyl monomer, a vinyl
cyan monomer, and a mixture thereof used to prepare graft
copolymer resin latex.
With respect to preparation of the rubber latex,
detailed description will be given below:
-- - - -
In the present invention, reaction was carried out for
5 to 15 hours after simultaneously adding 50 to 100 parts by
weight, out of 100 parts by weight of the conjugated diene
monomer, 1.0 to 1.5 parts by weight of the reactive
emulsifier, 0.1 to 0.6 parts by weight of a polymerization
initiator, 0.2 to 1.0 parts by weight of an electrolyte, 0.1
to 0.5 parts by weight of a gel content control agent, and
75 to 100 parts by weight of ion exchanged water.
Subsequently, the remainder of the conjugated diene monomer,
0.1 ,to 0.5 -parts by weight of the reactive emulsifier, and
0.05 to 0.5 parts by weight of the gel content control agent
were added simultaneously or sequentially, and then
20 polymerized for 10 to 20 hours at 70 to 85 'C, thereby
improving stability of latex. Accordingly, a us'e amount of
the emulsifier does not exceed 2.0 parts by weight and, as
such, rubber latex which may be used to prepare
thermoplastic resin having. superior surface clearness and
25 . superior gloss may be provided.
The polymerization initiator used in the step of
7-
preparing the rubber latex may be cumene hydroperoxide,
diisopropylbenzene hydroperoxide, tert-butyl hydroperoxide,
para methane hydroperoxide, or benzoyl peroxide as a fatsoluble
peroxide initiator; a metal salt select.ed from the
5 cjxouy curisisting of metal salts such as iron ( u ) , iron (m),
cobalt (n), cerium (W), and mixtures, as an oxidationreduction
system polymerization initiator; or a reductant
selected from the group consisting of reductants such as
dextrose, glucose, fructose, dihydroxyacetone, polyamine,
10 and mixtures thereof. A water-soluble initiator such as a
persulfate may be used.
The electrolyte may be at least one selected from the
group consisting of potassium chloride (KCl), sodium
chloride (NaCl), potassium. bicarbonate (KHC03), sodium
15 hydrogen carbonate (NaHC03), sodium carbonate (Na2C03),
potassium carbonate (K2C03), potassium hydrogensulfate
(KHSO3) I sodium hydrogensulfate (NaHS03) , potassium
pyrophosphate (K4P207), sodium pyrophosphate (Na4P207),
pstassium phosphate (K3PO4,) sodium phosphate (Na3P04), sodium
20 monohydro.genphosphate (Na2HP04) , and potassium
monohydrogenphosphate (K2HP0)4 .
The rubber latex may have a swelling index.of 5 to 25.
The rubber latex may have an average particle diameter
25 The rubber latex may have a gel content of 70 to 95%.
In the present invention, properties and
characteristics of the rubber latex may be measured as
follows.
1) Gel content and swelling index
Obtained rubber latex was solidified with a dilute
acid or a metal salt and then cleaned. Subsequently, the
rubber latex was dried for 24 hours in a 60°C oven, resulting
in a mass of rubber. The rubber mass was finely cut with a
pair of scissors, resulting rubber segments. 1 g of rubber
segments were inserted into 100 g of toluene and then stored
for 48 hours at room 'temperature in a dark room.
Subsequently, the segments were separated into sol and gel,
and then a gel content and a swelling index thereof were
measured according to Mathematical Formulas 1 and 2.
[Mathematical Formula 11
Gel content ( % ) = (weight of insoluble material
(gel)/weight of sample) * 100
[Mathematical Formula 21
Swelling index = weight of swelled gel/weight of gel
2) Particle diameters and distribution of particle
diameters
Particle diameters and distribution of particle
diameters were measured according to a Dynamic Light
Scattering (DLS) method, in which a laser ( ~ i c o m3~70 HPL
produced by Particle Sizing Systems, USA) was used as a
light source.
In addition, in the step of preparing the resin latex,
the aromatic vinyl monomer is used in an amount of 18 to 40
wt%, preferably 20 to 35 wt%, most preferably 25 to 30 wt%,
based on the total weight of the reactive mixture. When the
!J aromatic vinyl monomer is used in the amount described
above, yellowing is reduced and liquidity is not decreased.
In addition, superior chemical resistance - and impact
-- - -- - - - -- -- --
strength are exhibited.
The vinyl cyan monomer is used in an amount of 8 to 18
10 wt%, preferably 10 to 15 wt%, most preferably 11 to 13 wt%,
base,d on the total weight of the reactive mixture. When the
vinyl cyan monomer is used in the amount described above, a
yellowing phenomenon is reduced and liquidity is not
decreased. In addition, superior chemical resistance and
15 impact strength are exhibited.
In the step of preparing the resin latex, a molecular
weight control agent may be further comprised in an amdunt
of 0.1 to 0.4 wt%, preferably 0.2 to 0.5 wt%, most
preferably 0.25 to 0.3 wt%, based on the total weight of the
20 reactive mixture. When the molecular weight control agent is
comprised in the amount described above, the resin latex has
an advantageous molecular weight and, as such, liquidity is
not reduced and sufficient impact strength and chemical
resistance are exhibited.
25 The molecular weight control agent used in the step of
preparing the resin latex may be selected from the group
/-
consisting of ethyl-2-mercaptoethy1propionate1 2-
mercaptoethylpropionate, 2-mercaptoethanol, mercaptoacetic
acid., n-octylmercaptan, n-dodecylmercaptan, tdodecylmercaptan,
and mixtures thereof.
5 The aromatic vinyl monomer used in the step of
preparing the resin latex inay be selected from the group
consisting of styrene, a-mcthyl styrene, p-methyl styrene,
vinyltoluene, t-butyl styrene, chlorostyrene, substituents
thereof, and mixtures thereof.
10 The vinyl cyan monomer used in the step of preparing
the resin latex may be selected from the group consisting of
acrylonitrile, methacrylonitrile, substituents thereof, and
mixtures thereof.
In the step of preparing the resin latex, the reactive
15 emulsifier is used in an amount of 0.1 to 0.7 wt%,
preferably 0.1 to 0.5 wt%, most preferably 0.1 to 0.3 wt%,
a based on the total weight of the reactive mixture. When the
reactive emulsifier is used in the amount described above,
coagulum is not generated and a high polymerization
conversion ratio is exhibjted. In addition, waste of an
emul'sifier may be prevented, thereby being economically
effective.
The hydrophobic initiator used in the step of
preparing the resin latex may be cumene hydroperoxide,
25 diisopropylbenzene hydroperoxide, tert-butyl hydroperoxide,
para methane hydroperoxide, or benzoyl peroxide, as a fatsoluble
peroxide initiator; a metal salt selected from the
group consisting of metal ' salts, namely, iron (D), iron
( D ) , cobalt (a), cerium (IV), and mixtures thereof, as an
oxid'ation-reduction system polymerization initiator; or a
~ w l u c t a n t selected from the group consisting of reductants
such as dextrose, . glucose, fructose, dihydroxyacet.nn.e,
polyamine, and mixtures thereof. The hydrophobic initiator
is used in an amount of 0.1 to 0.4 wt%, preferably 0.2 to
0.4 wt%, based on the total weight of the reactive mixture.
When the hydrophobic initiator is used in the amount
described above, a polymerization conversion ratio is not
reduced and superior thermal stability is exhibited.
In the step of preparing the resin latex, the rubber
latex used to fill the remainder is obtained according to
the method described above. Preferably, the rubber latex has
an average particle diameter of 2500 to 3800 A and a gel
content of 70 to 95%.
Generally, during graft copolymerization, a monomer
mixture may be added by selectively using continuous
2.0 addition, batch addition, or continuous addition and batch
addition, and the addition methods are not specifically
limited. Preferably, 5 to 40 wt% of the total of the monomer
mixture is batch-added and the remainder of the monomer
mixture is continuously added. In addition, during the graft
25 copolymerization, temperature is elevated to 45 .to 85 'C to
control a graft reaction rate.
>'-
Time of the graft polymerization is preferably 4 hours
or less. A polymerization conversion ratio after reaction is
preferably 98.5 or more and a molecular weight of a polymer
is preferably 50,000 to 150,000 g/mol as a weight average
5 molecular weight.
Stability of the graft copolymer resin latex prepared
above was judged by 'measuring solid coagulum ( % ) according
to Mathematical Formula 3 below.
[Mathematical Formula 31
10 Solid coagulum ( % ) = {weight ( g ) of coagulum generated
in reactor/ weight (g) of total of rubber and monomers) x
When the amount of the solid coagulum is less than 0.5
15 wt%, stability of latex is superior and the amount of
coagulum is small. Accordingly, a graft polymer more
suitable for the present invention may be obtained.
In' addition, a graft ratio of the graft polymer is
measured as follows. The resin latex being a graft polymer
20 is solidified, cleaned, and dried, to obtain powder. 2 g of
the obtained powder is inserted into 300 m& of acetone and
stirred for 24 hours. The stirred solution is separated
using an ultracentrifuge and then the separated acetone
solution is added to methanol dropwise to obtain a part
25 which is not grafted. The obtained part is dried and then
the weight thereof is measured. Using the measured weight, a
graft ratio is calculated according to Mathematical Formula
4 below.
[Mathematical Formula 41
Graft ratio ( $ ) = (weight (g) of grafted monomers/
weight ( g ) of rubber) x 1UU
In this regard, when the graft ratio exceeds 20%,
superior gloss is exhibited.
The graft copolymer resin latex prepared as described
above may ,further comprise an antioxidant to prevent
oxidation during processing. The antioxidant may be a
phenolic antioxidant, a phosphoric antioxidant, or a
sulfuric antioxidant, which are generally used. Preferably,
tile antioxidant is comprised in an amount of 0.1 to 2.0
parts by weight with respect to 100 parts by weight of the
graft copolymerized latex, at a emulsified state having a
particle diameter of 0.5 to 2 ,m. Generally and preferably,
the antioxidant is slowly added to the graft copolymer resin
latex at' 40. to 80 °C while continuously stirring before an
20 agglomeration process.
A method of agglomerating the graft copolymer resin
latex prepared as described above comprises aging after
adding a metal salt or an acid, as a coagulant, to the graft
copolymer resin latex. As the coagulant, magnesium sulfate
25 (MgS04), calcium chloride (CaCl*), aluminum sulfate
(A12( SO4)3 ) , sulfuric acid, phosphoric acid, hydrochloric
acid, or the like is preferable.
The resin latex agglomerated as described above may be
obtained in a wet powder type, in which a moisture content
is 2 to 15 wt%, preferably 2 to 12 wt%, more preferably 5 to
10 wt%, through mechanical dehydration. The dehydration may
be carried out by mechanically adding pressure, preferably
dehydrating using a compression type dehydrator again after
dehydrating using a centrifugal dehydrator. Generally,
dehydration is carried out using a centrifugal dehydrator.
When the centrifugal dehydrator is used for dehydration, a
moisture.content of powder obtained through the dehydration
is approximately 30 wt%. On the other hand, when the
compression type dehydrator is used according to the present
invention, a moisture content of powder obtained through
dehydration.may be lowered up to approximately 10 wt%.
In the present invention, a moisture content may be
calculated according to Mathematical Formula 5 below at
200 O C .
[Mathematical Formula 51
Moisture content ( % ) = (weight (g) of latex resin
pulverulent body before drying - weight (g) of latex resin
pulverulent body after drying) /weight (g) of latex resin
pulverulent body before dryin9.X 100
Subsequently, the wet powder may be coextruded with an
aromatic vinyl-vinyl cyan copolymer prepared through mass
,*/,' -
polymerization or melt polymerization and, as 'such, may be
prepared in a pellet type.
The aromatic vinyl-vinyl cyan copolymer is preferably
a styrene-acrylonitrile (SAN) copolymer, which has a weight
5 average molecular weight of 140,000 and comprises 24% of a
vinyl cyan monomer, obtained through mass polymerization.
The wet powder and the aromatic vinyl-vinyl cyan
copolymer are mixed such that a final amount of rubber of a
finally obtained resin is preferably 10 to 30 wt%. Through a
10 wet powder extrusion process, in which extrusion and
kneading are carried out, comprising evaporating water of
the wet powder with the aromatic vinyl-vinyl cyan copolymer,
the thermoplastic resin having superior surface clearness
and superior gloss according to the present invention is
15 obtained, preferably in pellet form. That is, the wet powder
extr.usion may be carried out by co-extruding the wet powder
of the resin latex and aromatic vinyl-vinyl cyan copolymer
while applying vacuum to reduce pressure in a wet powder
extruder to atmospheric pressure, namely, 760 torr, or less.
20 Preferably, in the wet powder extrusion, addition of the
aromatic vinyl-vinyl cyan copolymer is carried out after
adding the wet powder of the resin latex to the co-extruder.
In this regard, co-extrusion of the wet powder of the resin
latex and the aromatic vinyl-vinyl cyan copolymer may be
25 carried out while applying vacuum to reduce pressure in the
co-extruder to atmospheric pressure or less before and after
1 ---
"'
addition of the aromatic vinyl-vinyl cyan copolymer. In this
case, contents of total remainders comprising monomer
I remainders in the resin are small and, as such, thermal
I stability and surface properties of the resin are greatly
In another embodiment, the reduced pressure during the
wet powder extrusion may be 1 to 760 torr, 1 to 100 torr, or
1. to 50 torr. When the reduced pressure is carried within
this pressure range, optimal thermal stability and surface
10 properties are exhibited.
Wet powder extrusion, in which extrusion and kneading
are carried out, comprising evaporating water in a 200 to
250 °C extruder, may be carried out after further adding
additives such as preferably a lubricant, a thermal
15 stabilizer, and the like to the mixture of the wet powder
and the aromatic vinyl-vinyl cyan cppolymer.
' In one embodiment, the water evaporation is a process
to evaporate water at high temperature. In this process,
remainders, boiling .points of which are low,, comprising
20 monomer remainders in a resin may be effectively removed.
Hereinafter, preferred examples will be provided for
better understanding of the present invention. It will be
apparent to those skilled in the art that these examples are
25 only provided to illustrate the present invention and
various modifications and alterations are possible within
./ ,-
-1'
the scope and technical range of the present invention. Such
modifications and alterations fall within the scope of
claims included herein.
[Example]
Example 1
(1) Preparation of rubber latex
75 parts by weight of ion exchanged water, 100 parts
by weight of 1,3-butadiene as a monomer, 1.5 parts by weight
10 of a C16-18 alkenyl succinic acid di-po'tassium salt (ELOPLA
AS100) as a reactive emulsifier, 2.0 parts by weight of
potassium carbonate (K2C03) as an electrolyte, 0.3 parts by
weight of tert-dodecylmercaptan (TDDM) as a molecular weight
control agent, and 0.2 parts by weight of potassium
15 persulfate as an initiator were simultaneously added to a
polymerization reactor (autoclave) under a nitrogen
atmosphere and then reacted for . 10 hours at a reaction
temperature of 70°C. When a polymerization conversion ratio
of the reactor reached 50%, 0.05 wt% of tert-
20 dodecylmercaptan was simultaneously added and reacted for 20
hours at 75 'C. When a polymerization conversion ratio is
90%, a polymerization inhibitor. was added thereto to
terminate the reaction. The resultant rubber latex was
analyzed. An average particle diameter of the resultant
25 rubber latex was 3100 A and'a gel content thereof was 85%.
(2) Preparation of graft copolymer resin latex
60 parts by weight (solid content) of poly butadiene
rubber latex having an average particle diameter of 3100 A
and a gel content .of 85%, 70 parts by weight of ion
exchanged water, 5 parts by weight of styrene as a monomer,
5 and 2 parts by weight of acrylonitrile were added to a
polymerization reactor (autoclave) substituted with
nitrogen, and then temperature of the reactor was maintained
- - - -
- - -
to 50°C. Subsequently, 0.05 parts by weight of cumene
hydroperoxide, 0.09 parts by weight of sodium pyrophosphate,
10 0.12' parts by weight of dextrose, and 0.002 parts by weight
of ferrous sulfide were simultaneously added to the
polymerization reactor. Subsequently, a mixture comprising
22 parts by weight of styrene, 10 parts by weight of
acrylonitrile, 0.25 parts by weight of ethyl-2-
15 mercaptoethylpropionate, and 0.12 parts by weight of cumene
hydroperoxide was continuously added to the polymerization
reactor while elevating a temperature of the mixture to 75 'C
for 2 hours. In parallel, 0.2 parts by weight (based on a
solid content, 28% aqueous solution) of a C16-18 alkenyl
I 20 succinic acid di-potassium salt (ELOPLA AS100) as a reactive
I
emulsifier was continuously added to the polymerization
reactor for 2 hours. After terminating continuous addition,
0.06 parts by weight of cumene hydroperoxide, 0.04 parts by
weight of sodium pyrophosphate, 0.06 parts by weight of
25 dextrose, and 0.001 parts by weight of ferrous sulfide were
added to the polymerization reactor. Temperature was
/'I
elevated to 80°C for 30 minutes and maintained for 30
minutes, and then reaction was terminated. Here, a
polymerization conversion ratio was 99%, a content of
coagulum was 0.03%, and a graft ratio was 38%.
5 After adding 0.5 parts by weight of an emulsion of an
antioxidant (winstay-L/IR1076 = 0.8/0.2) having an average
particle diameter of 0.9 ,um to the graft copolymer resin
latex, reaction of which was terminated, first agglomeration
was carried out in the presence of 2.0 wt% of MgS04 at 85 °C
10 and then second aging was carried out at 97 OC. Subsequently,
dehydration was carried out using a centrifugal dehydrator
to obtain a powdery graft copolymer having a moisture
content of approximately 30%. Resir! powder of 'the obtained
powdery graft copolymer having a moisture content of 30% was
15 secondarily. dehydrated again in a compression type
dehydrator such that a moisture content became approximately
lo%, to obtain wet powder.
(3) Kneading process (wet powder extrusion process)
To an ABS graft copolymer in a wet powder state
20 prepared as above, a general SAN resin (available from LG
chemical in Republic of Korea, grade: 80 HF, prepared
through mass polymerization; styrene-acrylonitrile copolymer
having a weight average molecular weight of '140,000 and
comprisirig . 24% of acrylonitrile), a lubricant, an
25 antioxidant, and a light stabilizer were added.
Subsequently, kneading was carried using a wet powder
J' -
extruder at 200 to 250 °C and the aromatic vinyl-vinyl cyan
copolymer was added to the wet powder extruder after adding
the wet powder of the resin latex to the wet powder
extruder. The wet powder of the resin latex and the aromatic
virlyl-vinyl cyan copolymer were co-extruded while applying
vacuum to reduce inner pressure of the wet powder extruder
to 8 tor'r before and after addition of the aromatic vinylvinyl
cyan copolymer, to prepare pellets. The pellets were
prepared into segments, rubber contents of which are 15%,
and properties of the segments were measured. Here, water,
monomer remainders, and the like were emitted through a
vacuum line connected to a middle portion of the extruder.
The pellets were injected again to measure properties.
Surface clearness was judged with the unaided eye.
15 Properties such as gloss, impact strength, liquidity, and
the like' were measured according to ASTM methods (impact
strength was measured according to ASTM D256, liquidity was
measured according to ASTM. D1238, and gloss was measured
according to ASTM D528). Whiteness was measured using a
20 HunLer color measuring instrument. available from Hunter
Labs, USA and compared. Thermal stability was compared
through an injection residence test (during injection,
residence for 20 minutes at 250 O C ) . Measured properties are
s~lrnmarized in Table 1.
25 ~ x a m ~ i2e
An experiment was carried out in the same manner as in
fr--
Example 1, except that 0.2 parts by weight of HITENOL KH-10
as a reactive emulsifier was continuously added for 2 hours.
Example 3
An experiment was carried out in the same manner as in
5 Example 1, except that 0.2 parts by weight of sodium dodecyl
ally1 sulfosuccinate (TREM LF-40) as a reactive emulsifier
was continuously added for 2 hours.
-Exam-pie 4
An experiment was carried out in the same manner as in
10 Example 1, except that a mixture of 0.15 parts by weight of
ethyl-2-mercaptoethylpropionate and 0.1 parts by weight of
tert- dodecylmercaptan was used as a molecular weight
controller.
Example 5
15 An experiment was carried out in the same manner as in
Example 1, except that 70 parts by weight (solid content) of
poly butadiene rubber latex having an average particle
diameter of 3100 A and a gel content of 85%, 100 parts by
weight of ion exchanged water, 7.2 parts by weight of
20 styrene as a monomer, ,and 2..8 parts by weight of
acrylonitrile were added to a polymerization reactor
(autoclave) substituted with nitrogen, and then temperature
of the reactor was maintained at 50°C. Subsequently, 0.05
parts by weight of cumene hydroperoxide, 0.09 parts by
25 weight of sodium pyrophosphate, 0.12 parts by weight of
dextrose, and 0.002 parts by weight of ferrous sulfide were
1 --*
,/ '
simultaneously added to the polymerization reactor.
Subsequently, a mixture comprising 14.0 parts by weiqht of
styrene, 6.0 parts by weight of acrylonitrile, 0.3 parts by
weight of ethyl-2-mercaptoethylpropionate, and 0.12 parts by
5 w e i y l ~ t of cumene hydroperoxide was continuously added to the
polymerization react0.r while elevating a temperature of the
mixture to 75 C for 2.5 hours. In parallel, 0.2 parts by
weight (based on solid content, 28% aqueous solution) of a
C16-18 alkenyl succinic acid di-potassium salt (ELOPLA
10 AS100) as a reactive emulsifier was continuously added to
the polymerization reactor for 2.5 hours.
Comparative Example 1
An experiment was carried out in the same manner as in
15 Example 1, except that 1.2 parts by weight of fatty acid
soap instead of a reactive emulsifier and 0.4 parts by
weight of tert-dodecylmercaptan 'as a molecular weight
controller were continuously added for 3 hours. After
continuous addition, 0.06 parts by weight of cumene
20 hydroperoxide, 0.04 parts by weight of sodium pyrophosphate,
0.06 parts by weight of dextrose, 'and 0.00'1 parts by weight
of ferrous sulfide were added and temperature was elevated
to 80 °C for 30 minutes. Properties measured after
terminating the reaction are summarized in Table.2.
Comparative Example 2
An experiment was carried out in the same manner as in
/.-- --
Example 1, except that 0.3 parts by weight of persulfate,
instead of cumene hydroperoxide, as an initiator and 0.4
parts by weight of tert-dodecylmercaptan as a molecular
weight controller were continuously added for 3 hours.
r; ar; ~ c a s ' u ~ eprdo perties are summarized in Table 2.
Comparative Example 3
Using only a centrifugal dehydrator instead of the
compression type dehydrator and the wet powder extrusion, a
pellet type resin having a moisture content of 0.8% was
10 obtained by drying the resin powder having a moisture
content of 30% with a dryer. The pellet type resin was
extruded and kneaded using a general double screw extruder
instead of wet powder extrusion.. Measured properties are
summarized in Table 2.
15
able 11
Graft ratio
( 3 )
Surface clearness
(judged with the unaided
eye
Surface gloss
Impact strength
(kg cm/cm)
Liquidity (MFR) (g/10
min)
Resident gloss change
rate ( % )
~esident color difference
reduction
(AE)
Mold deposition
Examp
le1
38
Excel
lent
110
31
23
2
< 2.0
Excel
Examp
le.4
37
Excel
lent
109
30
22
2
Excel
Examp
le5
32
Excel
lent
107
28
20
3
Excel
Examp
le2
39
Excel
lent
109
32
24
1
Excel
Examp
le3
38
Excel
lent
110
31
24
1
Excel
properties (judged with
the unaided eye)
As shown in Tables 1 and 2, it can be confirmed that,
Graft ratio
( % ) .
Surface clearness
(judged with the
unaided eye)
~ b r f a x o s s
Impact strength
(kg cm/cm)
Liquidity (MFR) (g/10
min)
Resident gloss change
rate ( % )
Resident color
difference reduction
(AE)
Mold deposition
prop.erties (judged
with the unaided eye)
according to the method of preparing the thermoplastic resin
lent
composition of the present invention, a superior
Comparative
Example 1
37
Normal
. ..
104
32
25
5