TECHNICAL FIELD
Cross-Reference to Related Applications
This application claims the benefit of Korean Patent Application No. 10-2014-0173861
filed on 05 December 2014 and Korean Patent Application No. 10-2015-0138309 filed on
01 October 2015 with the Korean Intellectual Property Office, the disclosures of which are
incorporated herein by reference in their entirety.
The present invention relates to a method of preparing a thermoplastic resin. More
particularly, the present invention relates to a thermoplastic resin having superior antibiosis
and melt-kneadability prepared through preparation of a graft copolymer latex and
coagulation of the graft copolymer latex with a specific antimicrobial agent, and a method
of preparing the thermoplastic resin to prepare a thermoplastic resin composition including
the thermoplastic resin.
BACKGROUND ART
Acrylonitrile-butadiene-styrene (hereinafter referred to as ABS) resin has superior
properties such as superior impact resistance, chemical resistance, processability and
surface gloss, thus being broadly used in office machines, electrical and electronic
products, automobile interior materials, toys, miscellaneous goods, and the like.
Recently, as interest on hygiene is increasing, research into ABS resin having antibacterial
characteristics to inhibit bacterial contamination and bacteria proliferation due to contact is
actively underway. Accordingly, various methods to provide antibacterial characteristics
are suggested. As a most general method, there is a method of adding an antimicrobial
agent to a resin. Used antimicrobial agents may be greatly classified into an organic
antimicrobial agent and an inorganic antimicrobial agent.
An inorganic antimicrobial agent is generally prepared by substituting an inorganic
substance such as zeolite, calcium phosphate, zirconium phosphate, or silica gel with
metallic ions having anti-bacterial function such as silver, zinc, or copper. Such an
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inorganic antimicrobial agent is currently utilized in various fields such as plastic products,
paper, or textile. However, so as to provide generally satisfied antibacterial characteristics
through addition of the inorganic antimicrobial agent, the inorganic antimicrobial agent
should be added in a large amount. In this case, the large amount of the antimicrobial agent
may cause discoloration and property deterioration of a resin, and production costs
increase.
For example, Korean Patent Laid-Open Publication No. 2006-0076792 suggests a method
of providing antibacterial characteristics by adding silver nanoparticles, as an inorganic
antimicrobial agent, to an ABS-based transparent resin. However, production costs greatly
increase due to expensive silver nanoparticles. In addition, toxicity to the human body of
the metal ions is being recently reported, and thus, attempts to limit use thereof have been
continuously made.
An organic antimicrobial agent may be re-classified into a unimolecular antimicrobial agent
having a small molecular weight and a polymeric antimicrobial agent. The unimolecular
organic antimicrobial agent having a small molecular weight has superior short-term
antibacterial characteristics, but persistence of antimicrobial activity thereof is very poor.
In addition, use of the unimolecular organic antimicrobial agent is limited due to acute
toxicity to the human body. On the other hand, the polymeric antimicrobial agent has
advantages such as increased antibacterial activity, reduced toxicity to the human body, and
extended persistence of antimicrobial activity, compared to an existing unimolecular
antimicrobial agent having a small molecular weight. However, such a polymeric
antimicrobial agent also has poor melt-kneadability to a resin, particularly an ABS-based
thermoplastic resin. Accordingly, when the polymeric antimicrobial agent is melt-kneaded
with the ABS-based thermoplastic resin by means of an extruder, or the like to prepare an
antibiotic ABS-based thermoplastic resin, mechanical properties of a prepared
thermoplastic resin are greatly decreased.
Therefore, so as to address the aforementioned problems, there is a need for research into
ABS-based thermoplastic resin having superior antibacterial characteristics without
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decrease of mechanical properties due to a polymeric antimicrobial agent uniformly
dispersed in a thermoplastic resin.
DISCLOSURE
Technical Problem
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 or preparing a thermoplastic resin
having superior antibiosis and melt-kneadability prepared through preparation of a graft
copolymer latex and coagulation of the graft copolymer latex with a specific antimicrobial
agent.
It is another object of the present invention to provide a method of preparing a
thermoplastic resin composition having excellent mechanical properties, fluidity, and
antibiosis due to inclusion of the thermoplastic resin.
It is yet another object of the present invention to provide a thermoplastic resin including
the antimicrobial agent and a thermoplastic resin composition including the same.
The above and other objects can be accomplished by the present invention described below.
Technical Solution
In accordance with one aspect of the present invention, provided is a method of preparing a
thermoplastic resin, the method including: i) a step of preparing a graft copolymer latex by
graft-polymerizing a) a conjugated diene rubber with b) at least one selected from the group
consisting of an aromatic vinyl compound, a vinyl cyan compound, and an acrylate-based
compound; and ii) a step of performing coagulation by adding a antimicrobial agent
polymer having a primary, secondary, tertiary, or quaternary amine group to the graft
copolymer latex.
In accordance with another aspect of the present invention, provided is a thermoplastic
resin, including a graft copolymer formed by graft-polymerizing a) a conjugated diene
5
rubber with b) at least one selected from the group consisting of an aromatic vinyl
compound, a vinyl cyan compound, and an acrylate-based compound; and a polymeric
antimicrobial agent having a primary, secondary, tertiary, or quaternary amine group.
In accordance with another aspect of the present invention, provided is a method of
preparing a thermoplastic resin composition, the method including: i) a step of preparing a
graft copolymer latex by graft-polymerizing a) a conjugated diene rubber with b) at least
one selected from the group consisting of an aromatic vinyl compound, a vinyl cyan
compound, and an acrylate-based compound; ii) a step of performing coagulation by adding
a polymeric antimicrobial agent having a primary, secondary, tertiary, or quaternary amine
group to the graft copolymer latex; iii) a step of obtaining a thermoplastic resin from the
coagulated graft copolymer; and iv) a step of melt-kneading 20 to 80% by weight of the
thermoplastic resin (A) with 20 to 80% by weight of a copolymer resin (B) formed by
polymerizing at least one selected from the group consisting of an aromatic vinyl
compound, a vinyl cyan compound, and an acrylate-based compound.
In accordance with yet another aspect of the present invention, provided is a thermoplastic
resin composition, including: 20 to 80% by weight of the thermoplastic resin (A) according
to claim 12 and 20 to 80% by weight of a copolymer resin (B) formed by polymerizing at
least one selected from the group consisting of an aromatic vinyl compound, a vinyl cyan
compound, and an acrylate-based compound.
Advantageous effects
As apparent from the fore-going, the present invention advantageously provides a
thermoplastic resin having superior antibiosis and melt-kneadability prepared through
preparation of a graft copolymer latex and coagulation of the graft copolymer latex with a
specific antimicrobial agent, and a method of preparing the thermoplastic resin to prepare a
thermoplastic resin composition including the thermoplastic resin.
6
Best mode
Now, the present invention will be described in more detail.
The present inventors continuously performed research into a method of uniformly
dispersing a polymeric antimicrobial agent in a thermoplastic resin to prevent deterioration
of mechanical properties. As a result, the present inventors confirmed that, when a graft
copolymer latex is coagulated using a polymeric antimicrobial agent having a primary,
secondary, tertiary, or quaternary amine group, a thermoplastic resin having superior
antibiosis and melt-kneadability can be prepared and a thermoplastic resin composition
having excellent mechanical properties, fluidity, and antibiosis can be prepared by using
the thermoplastic resin, thus completing the present invention.
Hereinafter, the method of preparing a thermoplastic resin according to the present
invention will be described in detail.
The method of preparing a thermoplastic resin includes i) a step of preparing a graft
copolymer latex by graft-polymerizing a) a conjugated diene rubber with b) at least one
selected from the group consisting of an aromatic vinyl compound, a vinyl cyan compound,
and an acrylate-based compound; and ii) a step of performing coagulation by adding a
polymeric antimicrobial agent having a primary, secondary, tertiary, or quaternary amine
group to the graft copolymer latex.
The graft-polymerizing of step (i) may be, for example, emulsion polymerization. The
emulsion polymerization may be performed by, for example, a batch-type, semi-batch, or
continuous process. During the emulsion polymerization of the graft copolymer, each
ingredient may be added, for example, batchwise or according to a graft addition method
wherein all or a portion of the ingredient is continuously added.
An emulsifier used in the emulsion polymerization of the graft copolymer of step (i) is not
specifically limited and may be particularly at least one selected from the group consisting
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of alkylaryl sulfonate; alkalimethylalkyl sulfate; sulfonated alkylester; and general
adsorbent emulsifiers such as a soap of fatty acid and an alkali salt of rosin acid.
In step (ii), the polymeric antimicrobial agent having the amine group may be used as
coagulant.
The coagulation of step (ii) may be performed at, for example, pH 2 to 6. Within this
range, heat stability of a resin decreases due to a remaining acidic material does not occur.
In addition, binding of the polymeric antimicrobial agent is easily performed, thus
exhibiting superior antibacterial characteristics.
In another embodiment, the polymeric antimicrobial agent of step (ii) may be dissolved in
an amount of 0.1 to 10% by weight, 0.1 to 5% by weight, or 0.5 to 3% by weight in an
aqueous acidic solution having a pH of 2 to 5. Within this pH range, superior coagulation
characteristics are provided and the polymer has superior stability during long storage
without decomposition of the polymer due to an acid. In addition, when the polymeric
antimicrobial agent is dissolved in a range of 0.1 to 10% by weight in an aqueous acidic
solution, superior coagulation characteristics are provided and non-coagulation does not
occur. In addition, the aqueous acidic solution has a viscosity suitable for the coagulation
process.
The aqueous acidic solution having a pH of 2 to 5 may be an aqueous acidic solution
including, for example, an organic acid or an inorganic acid. Particularly, the aqueous
acidic solution may be at least one selected from the group consisting of acetic acid, formic
acid, citric acid, butyric acid, palmitic acid, oxalic acid, sulfuric acid, hydrochloric acid,
phosphoric acid, nitric acid, and boric acid.
Specific examples of the coagulation of step (ii), which is not specifically limited, include a
batch-type coagulate method of adding a coagulant and then adding a latex, a continuous
coagulation method of continuously adding a coagulant and a latex, a mechanical
coagulation method of coagulating through mechanical shearing, and a slow coagulate
method.
8
The a) conjugated diene rubber may be added in an amount of, for example, 20 to 70% by
weight, 30 to 60% by weight, or 35 to 50% by weight based on the graft copolymer.
Within this range, superior impact strength is provided and grafting is completely
performed during polymerization, thereby having excellent mechanical properties.
The conjugated diene rubber may be, for example, a polymer of a conjugated diene
compound such as a butadiene polymer, a styrene-butadiene copolymer (SBR),
acrylonitrile-butadiene copolymer (NBR), ethylene-propylene diene copolymer (EPDM), or
a polymer derived therefrom.
The conjugated diene rubber latex may have an average particle diameter, for example, 800
to 6,000 Å, or 1,500 to 4,500 Å, or 2,000 to 4,000 Å. Within this average particle
diameter, the conjugated diene rubber latex has superior impact strength.
In another embodiment, a gel content of the conjugated diene rubber latex may be 60 to
95%, or 65 to 90%. Within this range, superior impact strength is provided.
In another embodiment, the conjugated diene rubber latex may have a swelling index of 12
to 40, or 15 to 30. Within this range, superior impact strength is provided.
The at least one selected from the group consisting of an aromatic vinyl compound, a vinyl
cyan compound, and an acrylate-based compound may be added in an amount of, for
example, 30 to 80% by weight, 40 to 70% by weight, or 50 to 75% by weight based on the
graft copolymer. Within this range, superior mechanical properties and property balance
are provided.
The aromatic vinyl compound may be added in an amount of 5 to 60% by weight, 15 to
55% by weight, or 30 to 50% by weight based on the graft copolymer. Within this range,
superior processability and property balance are provided.
9
The aromatic vinyl compound may be at least one selected from the group consisting of, for
example, styrene, α-methyl styrene, ο-ethyl styrene, p-ethyl styrene, and vinyltoluene.
The vinyl cyan compound may be added in an amount of, for example, 0 to 20% by weight
or 10 to 20% by weight based on the graft copolymer. Within this range, a coagulum is not
generated during graft-polymerizing, whereby productivity increases and the resin
composition maintains natural color thereof without yellowing.
The vinyl cyan compound may be at least one selected from the group consisting of, for
example, acrylonitrile, methacrylonitrile, and ethacrylonitrile.
The acrylate-based compound may be added in an amount of, for example, 0 to 60% by
weight or 0 to 40% by weight based on the graft copolymer. Within this range, superior
processability and property balance are provided.
The acrylate-based compound may be, for example, a (meth)acrylic acid alkylester
compound. Particularly, the acrylate-based compound may be at least one selected from
the group consisting of (meth)acrylic acid methyl ester, (meth)acrylic acid ethyl ester,
(meth)acrylic acid propyl ester, (meth)acrylic acid 2-ethylhexyl ester, (meth)acrylic acid
decyl ester, and (meth)acrylic acid lauryl ester.
The polymeric antimicrobial agent having the amine group may be added in an amount of,
for example, 1 to 20 parts by weight, 1 to 10 parts by weight, or 3 to 8 parts by weight,
based on 100 parts by weight of the graft copolymer. Within this range, excellent
antibacterial and coagulation characteristics and superior impact strength are provided.
50% or more of monomers, preferably main monomers, more preferably monomers that
constitute a main chain, constituting the polymeric antimicrobial agent having the amine
group includes a primary, secondary, tertiary, or quaternary amine group.
The polymeric antimicrobial agent having the amine group may have solubility to an
aqueous acidic solution having a pH of, for example, 1 to 5, and insolubility to an aqueous
acidic solution having a pH of, for example, 6 to 12. For example, the solubility is a
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property wherein 0.1 g or more of a solute dissolves in 100 g of a solvent at 23℃ under
atmospheric pressure, whereas the insolubility is a property wherein 0.1 g or more of a
solute does not dissolve under the same condition.
In another embodiment, 1 g or more of the polymeric antimicrobial agent having the amine
group may be dissolved in 100 g of an aqueous acidic solution having a pH of 1 to 5 at
23℃ under atmospheric pressure.
The polymeric antimicrobial agent having the amine group is not specifically limited so
long as it satisfies solubility to the pH and has the constituents. Particularly, the polymeric
antimicrobial agent may be at least one selected from the group consisting of
poly(diallyldimethyl ammonium chloride, polydicyandiamide, poly(N-vinylpyrrolidone),
polyethyleneimine, chitosan, modified chitosan, and polyvinylpyridine.
The thermoplastic resin according to the present invention includes a thermoplastic resin,
including a graft copolymer formed by graft-polymerizing a) a conjugated diene rubber
with b) at least one selected from the group consisting of an aromatic vinyl compound, a
vinyl cyan compound, and an acrylate-based compound; and a polymeric antimicrobial
agent having a primary, secondary, tertiary, or quaternary amine group.
A method of preparing the thermoplastic resin according to the present invention
composition includes i) a step of preparing a graft copolymer latex by graft-polymerizing a)
a conjugated diene rubber with b) at least one selected from the group consisting of an
aromatic vinyl compound, a vinyl cyan compound, and an acrylate-based compound; ii) a
step of performing coagulation by adding a polymeric antimicrobial agent having a
primary, secondary, tertiary, or quaternary amine group to the graft copolymer latex; iii) a
step of obtaining a thermoplastic resin from the coagulated graft copolymer; and iv) a step
of melt-kneading 20 to 80% by weight of the thermoplastic resin (A) with 20 to 80% by
weight of a copolymer resin (B) formed by polymerizing at least one selected from the
group consisting of an aromatic vinyl compound, a vinyl cyan compound, and an acrylatebased
compound.
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A method of polymerizing the copolymer resin formed by polymerizing the (B) at least one
selected from the group consisting of an aromatic vinyl compound, a vinyl cyan compound,
and an acrylate-based compound, which is not specifically limited, may be particularly
suspension polymerization, mass polymerization, or continuous mass polymerization.
The copolymer resin B may be, for example, prepared through a continuous process in
which a raw material feeding pump, a continuous stirring bath, a preliminary heating bath,
a volatilization bath, a copolymer transfer pump and an extruder are used.
The thermoplastic resin A and the copolymer resin B may be kneaded by means of a
kneader such as, for example, a banbury mixer, a single screw extruder, or a twin screw
extruder, a buss kneader.
The aromatic vinyl compound included in the copolymer resin B may be at least one
selected from the group consisting of, for example, styrene, α-methyl styrene, ο-ethyl
styrene, p-ethyl styrene, and vinyltoluene. The aromatic vinyl compound may be included
in an amount of 10 to 90% by weight, or 30 to 80% by weight, or 50 to 80% by weight
based on the copolymer resin B.
The vinyl cyan compound included in the copolymer resin B may be at least one selected
from the group consisting of, for example, acrylonitrile, methacrylonitrile, and
ethacrylonitrile. The vinyl cyan compound may be included in an amount of 10 to 70% by
weight, or 20 to 60% by weight, or 20 to 40% by weight based on the copolymer resin B.
The acrylate-based compound included in the copolymer resin B may be at least one
selected from the group consisting of, for example, (meth)acrylic acid methyl ester,
(meth)acrylic acid ethyl ester, (meth)acrylic acid propyl ester, (meth)acrylic acid
2ethylhexylester, (meth)acrylic acid decyl ester, and (meth)acrylic acid lauryl ester. The
acrylate-based compound may be included in an amount of 0 to 20% by weight or 0 to 10%
by weight, based on the copolymer resin B.
12
The thermoplastic resin according to the present invention composition includes 20 to 80%
by weight of the thermoplastic resin and 20 to 80% by weight of a copolymer resin (B)
formed by polymerizing at least one selected from the group consisting of an aromatic
vinyl compound, a vinyl cyan compound, and an acrylate-based compound.
The content of a conjugated diene rubber in the thermoplastic resin composition may be,
for example, 5 to 35% by weight, 5 to 25% by weight, or 10 to 20% by weight. When the
conjugated diene rubber is included within this range, superior impact strength, increased
processability, and superior rigidity are provided.
In another embodiment, the thermoplastic resin composition may include 60 to 95% by
weight, 75 to 95% by weight, or 80 to 90% by weight of a monomer mixture including at
least one selected from the group consisting of an aromatic vinyl compound, a vinyl cyan
compound, and an acrylate-based compound. Within this range, superior property balance
is provided.
The thermoplastic resin composition may have an impact strength, for example, 10
kg·cm/cm or more, 15 kg·cm/cm or more, or 20 kg·cm/cm or more.
In another embodiment, the thermoplastic resin composition may have a fluidity of 13 g/10
min (220℃, 10 kg) or more, or 15 g/10 min (220℃, 10 kg) or more.
The thermoplastic resin composition may randomly include an additive such as a heat
stabilizer, a photostabilizer, an antioxidant, an anti-static agent, an antimicrobial agent, or a
lubricant, within a range within which properties thereof are not affected.
In addition, the present invention provides a molded article made of the thermoplastic resin
composition. The molded article may be, for example, an office machine, an electrical and
electronic product, an automobile interior material, a toy, or a miscellaneous good.
Now, the present invention will be described in more detail with reference to the following
examples. These examples are provided only for illustration of the present invention and
should not be construed as limiting the scope and spirit of the present invention.
13
EXAMPLES
Example 1
A) Preparation of graft copolymer
40 parts by weight (based on a solid) of a butadiene rubber latex (gel content: 80%, average
particle diameter: 0.3 ㎛) prepared through emulsion polymerization with 120 parts by
weight of deionized water, 0.5 parts by weight of rosin acid potassium, 5.0 parts by weight
of acrylonitrile, 10 parts by weight of styrene, and 0.1 part by weight of tertiary dodecyl
mercaptan were fed batchwise into a polymerization reactor filled with a nitrogen
atmosphere and reaction temperature was elevated to 50℃. When an interior temperature
of the reactor reached 50℃, 0.1 parts by weight of tert-butyl hydroperoxide, 0.1 parts by
weight of dextrose, 0.1 parts by weight of sodium pyrophosphate, and 0.002 parts by
weight of ferrous sulfate were added to the reactor batchwise to initiate polymerization.
Subsequently, reaction temperature was elevated to 70℃ over 30 minutes. Subsequently,
12.6 parts by weight of acrylonitrile, 32.4 parts by weight of styrene, 25 parts by weight of
deionized water and 1.0 part by weight of rosin acid potassium were mixed. This resultant
monomer emulsion solution was continuously fed into the reactor over two hours. At the
same time, 0.15 parts by weight of tert-butyl hydroperoxide also was continuously fed into
the reactor over two hours. When feeding of the monomer emulsion solution was
terminated, 0.05 parts by weight of tert-butyl hydroperoxide, 0.05 parts by weight of
dextrose, 0.05 parts by weight of sodium pyrophosphate, 0.001 parts by weight of ferrous
sulfate were fed into the reactor batchwise. Subsequently, reaction temperature was
elevated to 80℃ over 30 minutes and aging was performed for 30 minutes, followed by
terminating the reaction. As a result, an ABS graft copolymer latex was prepared.
coagulation and aging
5 parts by weight (based on chitosan solid) of an aqueous chitosan solution, as a coagulant,
prepared by dissolving 2% by weight of chitosan in 2% by weight of an aqueous sulfuric
14
acid solution, as a polymeric antimicrobial agent, was added to the prepared ABS graft
copolymer latex, and coagulation was performed at 70℃. During the coagulation, pH was
3.5. After the coagulation, aging was carried out at 90℃, and dehydration and drying were
carried out. As a result, an ABS graft copolymer powder was obtained. Here, a generated
filtrate was analyzed through liquid chromatography. As a result, chitosan was not
detected.
B) Preparation of copolymer (SAN) resin
A raw material prepared by mixing 25 parts by weight of acrylonitrile and 75 parts by
weight of styrene with 30 parts by weight of toluene, as a solvent, and 0.15 parts by weight
of di-tert-dodecylmercaptan, as a molecular weight controller was continuously added to a
polymerization reactor filled with a nitrogen atmosphere, and reaction temperature was
maintained at 148℃. An average reaction time was three hours. A polymerized solution
discharged from the reactor was heated in a preliminary heating bath, and unreacted
monomers were vaporized in a volatilization bath. The temperature of a copolymer was
maintained at 210℃ and a copolymer resin was prepared into a pellet type by means of a
copolymer transfer pump and an extruder.
C) Preparation of thermoplastic resin composition (melt-kneading A with B)
40 parts by weight of the obtained ABS graft copolymer powder (A) and 60 parts by weight
of the copolymer (SAN) resin (B) were mixed in a general mixer, and 1.0 part by weight of
a lubricant and 0.2 parts by weight of an antioxidant were added to the mixer. Melting and
kneading were carried out at 200℃ by means of a twin screw extruder, thereby preparing a
pellet-type resin composition. The prepared pellet-type resin composition was injected and
prepared into a specimen for measuring properties.
Example 2
An experiment was carried out in the same manner as in Example 1, except that, in the
coagulation and aging processes, 5 parts by weight of an aqueous poly(diallyldimethyl
15
ammonium chloride) solution (based on poly(diallyldimethyl ammonium chloride) solid)
prepared by dissolving 2% by weight of poly(diallyldimethyl ammonium chloride) in 2%
by weight of an aqueous sulfuric acid solution, as a polymeric antimicrobial agent, were
used instead of the aqueous chitosan solution at 5 parts by weight (based on chitosan solid).
A filtrate generated in the coagulation and aging processes was analyzed through liquid
chromatography. As a result, poly(diallyldimethyl ammonium chloride) was not detected.
Example 3
An experiment was carried out in the same manner as in Example 1, except that, in the
coagulation and aging processes, 5 parts by weight of an aqueous poly(N-vinylpyrrolidone)
solution (based on poly(N-vinylpyrrolidone) solid) prepared by dissolving 2% by weight of
poly(N-vinylpyrrolidone) in 2% by weight of an aqueous sulfuric acid solution, as a
polymeric antimicrobial agent, was used instead of the aqueous chitosan solution at 5 parts
by weight (based on solid). A filtrate generated in the coagulation and aging processes was
analyzed through liquid chromatography. As a result, poly(N-vinylpyrrolidone) was not
detected.
Example 4
An experiment was carried out in the same manner as in Example 1, except that, the
coagulation and aging processes, 10 parts by weight of an aqueous chitosan solution (based
on chitosan solid) was used. A filtrate generated in the coagulation and aging processes
was analyzed through liquid chromatography. As a result, chitosan was not detected.
Example 5
An experiment was carried out in the same manner as in Example 1, except that, in the
coagulation and aging processes, 2 parts by weight of an aqueous chitosan solution (based
on chitosan solid) were used. A filtrate generated in the coagulation and aging processes
was analyzed through liquid chromatography. As a result, chitosan was not detected.
Comparative Example 1
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An experiment was carried out in the same manner as in Example 1, except that, in the
coagulation and aging processes, a 5 wt% aqueous sulfuric acid solution, as a polymeric
antimicrobial agent, was used in an amount of 1.8 parts by weight instead of the aqueous
chitosan solution at 5 parts by weight (based on chitosan solid).
Comparative Example 2
An experiment was carried out in the same manner as in Example 1, except that, in the
coagulation and aging processes, an aqueous chitosan solution was used in an amount of 1
part by weight (based on chitosan solid).
Comparative Example 3
An experiment was carried out in the same manner as in Comparative Example 1, except
that, in the melting and kneading (A) and (B), 20 parts by weight of a dried chitosan
powder were additionally added with a lubricant and an antioxidant, as additives.
Test Example
Properties of thermoplastic resin composition specimens prepared according to Examples 1
to 5 and Comparative Examples 1 to 3 were measured according to the following methods.
Results are summarized in Table 1 below.
Measurement methods
* Antibiosis: Using the specimens, staphylococcus reduction rates after incubation for 24
hours at 35℃ were measured according to KICM-FIR-1003, as an antimicrobial activity
test method.
* Impact strength (Notched Izod, kg·cm/cm): Measured according to ASTM D256, as a
standard measurement method, using 1/4" specimens.
* Melt index (g/10 min): Measured according to ASTM D1238 (220℃, 10 kg), as a
standard measurement method, using specimens.
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* Gel content and swelling index: Butadiene rubber latex was coagulated using a dilute acid
or a metallic salt and then washed. The washed latex was dried in a 60℃ vacuum oven for
24 hours. Obtained rubber mass was thinly cut with scissors. 1 g of rubber fragments was
added to 100 g of toluene and stored in a room-temperature dark room for 48 hours,
followed by being separated into a sol and a gel. The sol and gel were respectively dried.
A gel content was calculated according to [Mathematical Equation 1] below and a swelling
index was calculated according to [Mathematical Equation 2] below.
Mathematical Equation 1
【Mathematical Equation 2】
* Average particle diameter: Measured by means of 370 HPL manufactured Nicomp, US
according to a dynamic laser light scattering method.
Table 1
Classification Examples Comparative Examples
1 2 3 4 5 1 2 3
Impact
strength
(kg·cm/cm)
33.0 32.7 29.2 28.0 33.0 32.0 32.5 7.1
Melt index
(g/10 min)
23 20 22 19 22 24 23 12
Antibiosis ◎ ◎ ◎ ◎ ○ ○
* Antibiosis: Classified into three steps based on bacteria reduction rate (◎ – very
good, ○ - good, - bad).
As shown in Table 1, it can be confirmed that in Examples 1 to 5 in which chitosan, as a
polymeric antimicrobial agent having an amine group, poly(diallyldimethyl ammonium
18
chloride), and poly(N-vinylpyrrolidone) are used as coagulants according to the present
invention, excellent mechanical properties such as impact strength of 10 kg·cm/cm or more
and excellent fluidity such as melt index of 13 g/10 min or more are exhibited, the
thermoplastic resins included in the compositions thereof exhibit superior meltkneadability,
and excellent antibiosis are exhibited.
On the other hand, it can be confirmed that, in Comparative Example 1 in which a
polymeric antimicrobial agent having an amine group is not added in the coagulation and
aging processes and Comparative Example 2 in which the chitosan having an amine group,
a polymeric antimicrobial agent, is added in an amount of 1 part by weight, very poor
antibiosis is exhibited and, in Comparative Example 3 in which a polymeric antimicrobial
agent having an amine group is added in an amount of 20 parts by weight during the meltkneading,
antibiosis is exhibited, but impact strength and melt index are very poor.
In conclusion, the method of preparing the thermoplastic resin of the present invention
provides thermoplastic resin having superior antibiosis and melt-kneadability by
coagulating the graft copolymer latex using the polymeric antimicrobial agent having the
primary, secondary, tertiary, or quaternary amine group. Accordingly, it can be confirmed
that a thermoplastic resin having superior antibiosis and melt-kneadability is provided
through the present invention and a thermoplastic resin composition including the
thermoplastic resin exhibits excellent mechanical properties, fluidity, and antibiosis.
19

WE CLAIM:
1. A method of preparing a thermoplastic resin, the method comprising:
i) preparing a graft copolymer latex by graft-polymerizing a) a conjugated diene
rubber with b) at least one selected from the group consisting of an aromatic vinyl
compound, a vinyl cyan compound, and an acrylate-based compound; and
ii) performing coagulation by adding a polymeric antimicrobial agent having a
primary, secondary, tertiary, or quaternary amine group to the graft copolymer
latex.
2. The method according to claim 1, wherein the coagulation of ii) is carried out under
pH 2 to 6.
3. The method according to claim 1, wherein the antimicrobial agent polymer of ii) is
added as a dissolved solution of 0.1 to 10% by weight in an aqueous acidic solution
having a pH of 2 to 5.
4. The method according to claim 1, wherein the polymeric antimicrobial agent having
the amine group is added in an amount of greater than 1 parts by weight and less
than 20 parts by weight based on 100 parts by weight of the graft copolymer.
5. The method according to claim 1, wherein 50% or more of monomers constituting
the polymeric antimicrobial agent having the amine group are monomers containing
a primary, secondary, tertiary, or quaternary amine group.
6. The method according to claim 1, wherein the polymeric antimicrobial agent having
the amine group is at least one selected from the group consisting of
poly(diallyldimethyl ammonium chloride), polydicyandiamide, poly(Nvinylpyrrolidone),
polyethyleneimine, chitosan, modified chitosan, and
polyvinylpyridine.
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7. The method according to claim 1, wherein 1 g or more of the polymeric
antimicrobial agent having the amine group is dissolved at 23℃ based on 100 g of
an aqueous acidic solution having a pH of 1 to 5.
8. The method according to claim 1, wherein the a) conjugated diene rubber is added
in an amount of 20 to 70% by weight, and the b) at least one selected from the
group consisting of an aromatic vinyl compound, a vinyl cyan compound, and an
acrylate-based compound is added in an amount of 30 to 80% by weight.
9. The method according to claim 1, wherein the acrylate-based compound is at least
one selected from the group consisting of (meth)acrylic acid methyl ester,
(meth)acrylic acid ethyl ester, (meth)acrylic acid propyl ester, (meth)acrylic acid 2-
ethylhexyl ester, and (meth)acrylic acid decyl ester.
10. The method according to claim 1, wherein the aromatic vinyl compound is at least
one selected from the group consisting of styrene, α-methyl styrene, ο-ethyl styrene,
p-ethyl styrene, and vinyltoluene.
11. The method according to claim 1, wherein the vinyl cyan compound is at least one
selected from the group consisting of acrylonitrile, methacrylonitrile, and
ethacrylonitrile.
12. A thermoplastic resin, comprising a graft copolymer formed by graft-polymerizing
a) a conjugated diene rubber with b) at least one selected from the group consisting
of an aromatic vinyl compound, a vinyl cyan compound, and an acrylate-based
compound; and a polymeric antimicrobial agent having a primary, secondary,
tertiary, or quaternary amine group.
13. A method of preparing a thermoplastic resin composition, the method comprising:
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i) preparing a graft copolymer latex by graft-polymerizing a) a conjugated diene
rubber with b) at least one selected from the group consisting of an aromatic vinyl
compound, a vinyl cyan compound, and an acrylate-based compound;
ii) performing coagulation by adding a polymeric antimicrobial agent having a
primary, secondary, tertiary, or quaternary amine group to the graft copolymer
latex;
iii) obtaining a thermoplastic resin from the coagulated graft copolymer; and
iv) melt-kneading 20 to 80% by weight of the thermoplastic resin (A) with 20 to
80% by weight of a copolymer resin (B) formed by polymerizing at least one
selected from the group consisting of an aromatic vinyl compound, a vinyl cyan
compound, and an acrylate-based compound.
14. A thermoplastic resin composition, comprising: 20 to 80% by weight of the
thermoplastic resin (A) according to claim 12 and 20 to 80% by weight of a
copolymer resin (B) formed by polymerizing at least one selected from the group
consisting of an aromatic vinyl compound, a vinyl cyan compound, and an acrylatebased
compound.
15. The thermoplastic resin composition according to claim 14, wherein a content of a
conjugated diene rubber in the thermoplastic resin composition is 5 to 35% by
weight.
16. The thermoplastic resin composition according to claim 14, wherein the
thermoplastic resin composition has an impact strength of 10 kg·cm/cm or more.