KR20190066870A - Method For Preparing Graft Copolymer, Graft Copolymer Having Improved Impact Resistance Prepared Therefrom, And Thermoplastic Resin Composition Comprising Thereof - Google Patents

Abstract

The present invention provides: a method for manufacturing a graft copolymer comprising a step of introducing a polymer coagulant having an average particle diameter of 1200Å or more into a diene-based polymer and coagulating the same and a step of emulsion-polymerizing a coagulated conjugated diene-based polymer, an aromatic vinyl-based monomer, and vinyl cyanide monomer; the graft copolymer having excellent impact resistance manufactured from the same; and a thermoplastic resin composition comprising the same.

Description

TECHNICAL FIELD The present invention relates to a graft copolymer, a graft copolymer having excellent impact resistance, and a thermoplastic resin composition containing the same. Also disclosed is a thermoplastic resin composition containing the thermoplastic resin composition.

The present invention relates to a method for producing a graft copolymer, a graft copolymer excellent in impact resistance produced therefrom, and a thermoplastic resin composition containing the same.

Acrylonitrile-butadiene-styrene (ABS) resins are widely used in automotive products, electrical and electronic equipment due to stiffness and chemical resistance of acrylonitrile, butadiene and styrene processability, mechanical strength and beautiful appearance characteristics. Electronic products and office equipment.

Such an ABS resin is generally produced by continuous bulk polymerization and emulsion polymerization. The ABS resin produced by the emulsion polymerization has a relatively good impact resistance, a good balance of physical properties such as fluidity, and excellent glossiness as compared with a resin produced by continuous bulk polymerization.

In the case of an ABS resin produced through emulsion polymerization, styrene and acrylonitrile are graft copolymerized with a diene rubber represented by butadiene in order to improve the impact resistance, and then this is copolymerized with styrene-acrylonitrile (SAN) copolymer, polystyrene , Polymethyl methacrylate, or the like is used. However, the rubber added to improve the impact resistance has problems such as poor coloring property compared to resins such as SAN. Accordingly, there is an attempt to improve the impact strength of the graft copolymer in order to provide a thermoplastic resin composition excellent in impact resistance while controlling the rubber content within a certain range.

On the other hand, the impact strength of the ABS copolymer can be controlled according to the particle size of the diene polymer. In order to obtain a proper particle size, it has been common to use acetic acid to emulsify and polymerize particles after relatively short time. However, acetic acid has a disadvantage in that it is difficult to administer, and when it is coagulated, soap such as dioctyl sodium sulfosuccinate (DOSS) should be used.

Accordingly, the present inventors have been able to control the particle size distribution (PSD) of the coagulated diene polymer by using a polymer coagulant to agglomerate and expand the diene polymer and to use a polymer coagulant having an average particle size of 1200 ANGSTROM or more And completed the present invention.

Korean Patent Publication No. 2007-0070687 (2007.07.04)

The present invention aims to provide a graft copolymer excellent in impact resistance and a method for producing the graft copolymer.

It is another object of the present invention to provide a thermoplastic resin composition containing a graft copolymer excellent in impact resistance and a molded article obtained from the thermoplastic resin composition.

In one embodiment of the present invention, a polymer coagulant having an average particle diameter of 1200 ANGSTROM or more is added to a diene polymer and coagulated; And emulsion-polymerizing the coagulated diene polymer, the aromatic vinyl monomer, and the vinylcyanide monomer. The present invention also provides a method for producing a graft copolymer.

Another embodiment of the present invention provides a graft copolymer having an impact strength of 20 to 30 kgf · m / m produced by the above method.

Another embodiment of the present invention relates to the above graft copolymer; And a styrene-acrylonitrile (SAN) copolymer.

According to the production method of the present invention, it is possible to provide a graft copolymer having excellent impact resistance by using a polymer flocculant having an average particle diameter of 1200 ANGSTROM or more, and a thermoplastic resin composition containing the graft copolymer.

Hereinafter, the present invention will be described in detail in order to facilitate understanding of the present invention.

The terms and words used in the present specification and claims should not be construed as limited to ordinary or dictionary terms and the inventor may appropriately define the concept of the term in order to best describe its invention It should be construed as meaning and concept consistent with the technical idea of the present invention.

The method for preparing a graft copolymer according to the present invention comprises the steps of charging a diene polymer with a polymer flocculant having an average particle size of 1200 ANGSTROM or more and flocculating the same; And emulsion-polymerizing the coagulated diene polymer, the aromatic vinyl monomer and the vinylcyanate monomer.

Hereinafter, each step of the method for producing a graft copolymer according to one embodiment of the present invention will be described in more detail.

(1) Flocculation step of diene polymer

The present invention is characterized in that a polymer coagulant having an average particle size of 1200 ANGSTROM or more is used to coagulate the diene polymer and pass it through the process of enlarging it. When the polymer coagulant having an average particle diameter of 1200 ANGSTROM or more is used, the size of the diene polymer is maintained at 3000 to 3500 ANGSTROM even after the lapse of time, and the particle size distribution (PSD: Particle Size Distribution) of the coagulated diene polymer is narrowed, The mechanical properties of the copolymer, i.e., the impact strength, are improved. Preferably, the polymer flocculant has an average particle diameter of 1200 to 1600 Å, preferably 1300 to 1500 Å, and more preferably 1200 to 1400 Å.

In this case, the average particle diameter of the diene polymer before aggregation is preferably 800 to 1200 angstroms, more preferably 950 to 1100 angstroms, and most preferably 1000 angstroms. When the above-mentioned range is satisfied, not only the diene polymer aggregates in a preferable particle diameter range, but also the particle size distribution (PSD) can be controlled within a narrow range.

The average particle diameter of the diene polymer agglomerated through the non-enlarged process is preferably 1400 to 4500 Å, more preferably 2800 to 4000 Å, still more preferably 3000 to 3800 Å, and most preferably 3200 to 3500 Å. The agglomerated diene polymer has a large change in particle size even after the elapse of time, and the average particle diameter change rate is maintained within the range of 0.005 to 0.05%, preferably 0.007 to 0.02%.

In the present invention, the average particle diameter change rate of the diene polymer is calculated according to the following formula:

[Equation 1]

Polymer coagulant was added from 30 minutes to 120 minutes. Change in particle diameter of diene polymer (%) = | Average particle diameter after 120 minutes of introduction of polymer flocculant - Average particle diameter after 30 minutes of introduction of polymer flocculant | Average particle diameter after 30 minutes of addition of polymer flocculant 100

In the present invention, the particle size of the polymer flocculant, the diene polymer and the graft copolymer can be measured with a particle size analyzer (NICOMP 380).

The Standard Deviation measured by the particle size analyzer NICOMP 380 software in the particle size distribution (PSD) of the aggregated diene polymer is less than 0.45, preferably less than 0.40, more preferably less than 0.35.

The diene polymer may be at least one member selected from the group consisting of a butadiene polymer, a butadiene-styrene copolymer, a butadiene-acrylonitrile copolymer, an ethylene-propylene copolymer and derivatives thereof, and among these, a butadiene polymer is preferable. The diene polymer may have a structure in which a double bond and a single bond are alternately arranged.

The diene polymer may be in the form of a diene rubber latex in which a conjugated diene rubber polymer prepared by polymerization of a conjugated diene monomer is dispersed in water in a colloidal state.

For example, the conjugated diene-based monomer may be at least one selected from the group consisting of 1,3-butadiene, isoprene, chloroprene, and piperylene, and is preferably 1,3-butadiene.

The diene polymer may be contained in an amount of 20 to 70% by weight, 30 to 60% by weight or 40 to 60% by weight based on the total weight of the diene polymer, the aromatic vinyl monomer and the vinyl cyanide monomer, By weight to 60% by weight. When the above-mentioned range is satisfied, the impact resistance, workability, and transparency of the thermoplastic resin composition as a final product can be more excellent.

The polymer flocculant is, for example, an unsaturated carboxylic acid polymer or an unsaturated carboxylic acid ester polymer, and specific examples thereof include carboxylic acid or ester monomers thereof; And a comonomer having a functional group.

The unsaturated carboxylic acid or its ester monomer may be, for example, at least one selected from the group consisting of an ethylenically unsaturated carboxylic acid, an ester monomer thereof, and an acrylate monomer. Specifically, it may be at least one selected from the group consisting of ethyl acrylate and butyl acrylate.

The unsaturated carboxylic acid polymer may further include at least one comonomer selected from the group consisting of a C _4-6 conjugated double bond monomer, a monovinyl aromatic hydrocarbon monomer, and a vinyl cyan monomer.

The functional group may be at least one member selected from the group consisting of, for example, an amide group, an alcohol group, a carboxylic acid group, a sulfonic acid group, a phosphoric acid group and a boric acid group.

The comonomer having the functional group may be at least one selected from the group consisting of acrylic acid, methacrylic acid, acrylamide, and methacrylamide.

Specifically, the polymer flocculant is an alkyl acrylate-derived unit; And units derived from at least one of (meth) acrylic acid and (meth) acrylamide. More specifically, a unit derived from at least one of ethyl acrylate and butyl acrylate; And units derived from at least one of acrylic acid, methacrylic acid, acrylamide and methacrylamide.

Also, the polymer flocculant is a core-shell structure and comprises, based on the total weight of the core and the shell, 30 to 75% by weight of the core; And 25 to 70% by weight of the shell.

In addition, the core of the polymer flocculant may comprise less than 10% by weight of units derived from math (acrylic acid) and the shell may comprise from 10 to 20% by weight, preferably from 12 to 18% by weight, have.

The polymer flocculant may be added in an amount of 1 to 10 parts by weight, preferably 3 to 5 parts by weight, more preferably 1 to 3 parts by weight, based on 100 parts by weight of the diene polymer. In this case, , And the particle size distribution is controlled in a narrow range.

(2) Emulsion polymerization step

In the present invention, the emulsion polymerization step follows a general emulsion polymerization method.

As the emulsifier used in the emulsion polymerization, a general adsorptive emulsifier or a reactive emulsifier can be used, or a mixture thereof can be used. Examples of the emulsifier include acrylate acrylic acid copolymer which is saponified with sodium hydroxide having a weight average molecular weight of 4,000, sulfate salt of polyoxyethylene allylglycidylnonylphenyl ether, ELEMINOL RS series (manufactured by Sanyo Kasei) ), An alkyl aryl sulfonate, an alkali metal alkyl sulfate, a sulfonated alkyl ester, a fatty acid soap, or an alkali salt of rosin acid.

The emulsifier may be added in an amount of 0.15 to 2.0 parts by weight, 0.3 to 1.5 parts by weight, or 0.5 to 1.2 parts by weight based on 100 parts by weight of the sum of the diene polymer, the aromatic vinyl monomer and the vinylcyanate monomer, To 1.2 parts by weight. When the above-mentioned range is satisfied, the emulsion polymerization can be easily carried out, and the residual amount of the emulsifier in the graft copolymer can be minimized.

The emulsion polymerization may be carried out by introducing a monomer or the like into the reactor in a batch or by introducing a part of monomers or the like into the reactor before starting the emulsion polymerization and continuously introducing the remainder after the initiation, can do.

The polymerization initiator used in the polymerization may be at least one selected from the group consisting of a water-soluble initiator, a fat-soluble initiator, and an oxidation-reduction catalyst.

The water-soluble initiator may be persulfate, and the persulfate may be potassium persulfate, sodium persulfate, ammonium persulfate and the like. The fat-soluble initiator may be cumene hydroperoxide, diisopropylbenzene hydroperoxide, azobisisobutylonitrile, tertiary butyl hydroperoxide, parramentane hydroperoxide, benzoyl peroxide, and the like. The oxidation-reduction catalyst may be sodium formaldehyde sulfoxylate, sodium ethylenediamine tetraacetate, ferrous sulfate, dextrose, sodium pyrophosphate, sodium pyrophosphate unhyydrosus, sodium sulfate, and the like.

The initiator may be added in an amount of 0.001 to 1.0 part by weight, 0.01 to 0.5 part by weight, or 0.02 to 0.1 part by weight based on 100 parts by weight of the sum of the diene polymer, the aromatic vinyl monomer and the vinylcyano monomer, To 0.1 part by weight. When the above-mentioned range is satisfied, the emulsion polymerization can be easily carried out, while the residual amount of the initiator in the graft copolymer can be minimized.

In addition, an electrolyte, a molecular weight regulator, a pH adjuster, and the like may be added before the initiation of polymerization.

The electrolyte is selected from the group consisting of potassium chloride, sodium chloride, potassium bicarbonate, sodium bicarbonate, potassium carbonate, sodium carbonate, potassium sulfate, sodium sulfate, potassium hydrogen sulfate, sodium hydrogen sulfate, potassium pyrophosphate unhyydrosus, sodium pyrophosphate Potassium phosphate, sodium phosphate, dipotassium hydrogen phosphate, disodium hydrogen phosphate, and the like.

The molecular weight regulator may be selected from the group consisting of mercaptans such as a-methylstyrene dimer, t-dodecyl mercaptan, n-dodecyl mercaptan and octyl mercaptan, halogenated hydrocarbons such as methylene chloride, methylene bromide, tetraethylthiuram disulfide , Dipentamethylenethiuram disulfide, diisopropylkantogen disulfide, and the like. Preferably t-dodecylmercaptan.

The molecular weight modifier may be added in an amount of 0.1 to 1.0 part by weight, 0.2 to 0.8 part by weight, or 0.4 to 0.6 part by weight based on 100 parts by weight of the sum of the diene polymer, the aromatic vinyl monomer and the vinylcyanate monomer, 0.4 to 0.6 parts by weight.

The aromatic vinyl-based monomer may be at least one member selected from the group consisting of styrene,? -Methylstyrene,? -Ethylstyrene, and p-methylstyrene, and is preferably styrene.

The aromatic vinyl monomer may be used in an amount of 0.1 to 40 wt%, 7 to 30 wt%, 10 to 30 wt%, or 10 to 20 wt% based on the total weight of the diene polymer, aromatic vinyl monomer, , And 10 to 20% by weight thereof is preferable. When the above-mentioned range is satisfied, the transparency of the thermoplastic resin composition as a final product can be further improved.

The vinyl cyano based monomer may be at least one member selected from the group consisting of acrylonitrile, methacrylonitrile, phenyl acrylonitrile, and? -Chloroacrylonitrile, and is preferably acrylonitrile.

The vinyl cyanide monomer is used in an amount of 0.1 to 40% by weight, 7 to 30% by weight, 10 to 30% by weight, or 10 to 20% by weight, based on the total weight of the diene polymer, the aromatic vinyl monomer and the vinyl cyanide monomer , And 10 to 20% by weight thereof is preferable. When the above-mentioned range is satisfied, the transparency of the thermoplastic resin composition as a final product can be further improved.

Another embodiment of the present invention provides a graft copolymer having an impact strength of 20 to 30 kgf · m / m, produced by the above method. Preferably, the graft copolymer has an impact strength of 22 to 26 kgf · m / m.

The graft copolymer may have an average particle diameter of 3,000 to 5,500 Å, 3,000 to 5,000 Å, or 3,200 to 4,000 Å. When the above-mentioned range is satisfied, it is excellent in impact resistance, so that it can be applied to home appliances such as home appliances, back covers for mobile phones and notebooks, automobile interior and exterior materials, and legos.

The graft copolymer preferably contains 40 to 70% by weight of a diene polymer, 10 to 40% by weight of an aromatic vinyl compound, and 10 to 40% by weight of a vinyl cyan compound.

Another embodiment of the present invention provides a thermoplastic resin composition comprising the graft copolymer. The thermoplastic resin composition may further comprise conventional components, and may further include, for example, a SAN (styrene acrylonitrile) copolymer.

Hereinafter, embodiments of the present invention will be described in detail so that those skilled in the art can easily carry out the present invention. The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein.

≪ Preparation of graft copolymer &

Example 1

Preparation of polymer flocculant

An initial charge comprising an amount of water, butyl acrylate (10 wt% of the total amount of monomer) and an emulsifier (DOSS), and an initiator (potassium persulfate) were heated to a temperature of 80 캜.

Subsequently, additional amounts of butyl acrylate, DOSS and initiator were added for 90 minutes. Here, the amount of butyl acrylate added is 40% by weight of the total amount of the monomers.

A mixture of methacrylic acid (MAA), water and butyl acrylate (BA) was then introduced, and DOSS and initiator were also introduced. The remaining monomer was added for 90 minutes, where the monomer mixture consisted of 82% by weight of butyl acrylate and 18% by weight of MAA. Upon completion of the addition, the mixture was maintained at 80 DEG C for 1 hour. The total amount of the emulsifier (DOSS) injected in Example 1 is 0.25 parts by weight based on 100 parts by weight of the rubber.

The core-shell type (core / shell content (wt%) = 50/50, core: BA, MAA (without MAA), shell: BA, MAA )], And a polymer flocculant having an average particle diameter of 1400 Å was prepared.

The particle size distribution (measured by hydrodynamic fractionation) of the resulting coagulated latex was approximately d ₅₀ 140 nm.

Preparation of graft copolymer

As the diene polymer, PBL1000 and Lu100 (LG Chemical) having an average particle diameter of 1,000 ANGSTROM were used.

3.3 parts by weight of the above polymer coagulant (based on 100 parts by weight of rubber) was added to the diene polymer and stirred. After 30 minutes and 120 minutes of sampling, the particle size was measured using a particle size analyzer (NICOMP 380). (See Table 1 below)

Styrene and acrylonitrile were grafted to the coagulated diene polymer by emulsion polymerization to prepare an ABS graft copolymer latex. Thereafter, the ABS graft copolymer was aggregated with MgSO ₄ , washed, dehydrated and dried to obtain a powder.

Example 2

A graft copolymer was prepared in the same manner as in Example 1, except that the polymer flocculant having an average particle diameter of 1200 Å was used, which was formed by changing the emulsifier content to 0.375 part by weight based on 100 parts by weight of rubber instead of the polymer flocculant having an average particle diameter of 1400 Å .

Comparative Example 1

A graft copolymer was prepared in the same manner as in Example 1, except that the polymer flocculant having an average particle diameter of 1,000 ANGSTROM, which was formed by changing the emulsifier content to 0.5 part by weight based on 100 parts by weight of rubber instead of the polymer flocculant having an average particle diameter of 1400 ANGSTROM .

Comparative Example 2

A graft copolymer was prepared in the same manner as in Example 1, except that the polymer flocculant having an average particle diameter of 800 Å was used in place of the polymer flocculant having an average particle diameter of 1400 Å and the emulsifier content was changed to 0.625 parts by weight based on 100 parts by weight of rubber .

Comparative Example 3

A graft copolymer was prepared in the same manner as in Example 1, except that the polymer flocculant having an average particle diameter of 1800 Å was used instead of the polymer flocculant having an average particle diameter of 1400 Å, in which the emulsifier content was changed to 0.1 part by weight based on 100 parts by weight of rubber .

Experimental Example

The obtained graft copolymer powder and SAN copolymer (80HF of LG Chemical) were mixed in a mixer and then pelletized using an extruder. Then, a specimen for physical property measurement was prepared using an extruder. The following physical properties of each specimen were measured and are shown in Table 1.

1) Impact strength (kgf · m / m): The thermoplastic resin composition was injected and then measured at a rate of 1/4 in accordance with ASTM D256-10.

2) Aggregate content (% by weight): Weight of the solidified product in the reaction tank (g) / Weight of total rubber and monomer (g) X 100

3) Addition of polymer flocculant 30 minutes to 120 minutes Change of particle diameter of diene polymer (%) = | Average particle diameter after 120 minutes of introduction of polymer flocculant - Average particle diameter after 30 minutes of introduction of polymer flocculant | Average particle diameter after 30 minutes of addition of polymer flocculant - 100

division Example 1 Example 2 Comparative Example 1 Comparative Example 2 Comparative Example 3 Particle size (Å) of polymer flocculant 1,400 1,200 1,000 800 1,800 After the addition of the polymer flocculant, the size (Å) 30 minutes 3,325 3,350 3,300 3,330 3,300 120 minutes 3,350 3,300 3,000 2,900 3,800 Change in particle diameter of the diene polymer (%) from 30 minutes to 120 minutes after the introduction of the polymer flocculant 0.0075 0.015 0.1 0.13 0.15 Size distribution of diene polymer
Standard Deviation <0.40 <0.45 <0.50 <0.55 <0.60 Aggregate content (% by weight) <0.01 <0.01 0.01 0.015 0.03 Impact strength (kgf · m / m) 25 23 19 17 15

In the above results, the size of the diene polymer was maintained at 3,300 Å or more after the addition of the polymer flocculant. Further, the size of the diene polymer was measured after 30 minutes and 120 minutes after the introduction of the polymer flocculant, respectively. As a result, it was confirmed that the particle size change ratio was less than 0.1% and the particle size change was very small.

In the above table, the size distribution of the diene polymer is a standard deviation measured by a particle size analyzer NICOMP 380 software after 120 minutes from the introduction of the polymer flocculant. The smaller the value, the more the normal distribution is followed.

According to the embodiment of the present invention, the standard deviation of the aggregated diene polymer size distribution is controlled to a small numerical value as less than 0.45, and thus the impact strength of the graft copolymer is excellent.

On the other hand, in Comparative Examples 1 and 2 in which the mean particle diameter of the polymer flocculant was 1,000 Å or less and Comparative Example 3 in which the average particle diameter was 1,800 Å, the rate of change of the size of the diene polymer was 0.1% , And the standard deviation of the size distribution of the diene polymer was also relatively high. Thus, it can be confirmed that the impact strength is lower than that of the embodiment of the present invention.

On the other hand, coagulation means an excessively large unstable coagulum. According to the manufacturing method of the embodiment of the present invention, the coagulation amount is controlled to a very small amount. This has the advantage that there is less damage to the mechanical properties of the final product, the yield of the product is increased, and the need for factory cleaning is reduced.

On the other hand, in the case of the comparative example, the larger the average particle diameter of the polymer flocculant is, the more the flocculant content is shown, and in the case of Comparative Example 3, the flocculant content is 0.03% by weight. Therefore, there is a disadvantage in the operation of the process as compared with the present invention.

Claims (14)

Adding a polymer flocculant having an average particle size of 1200 ANGSTROM or more to the diene polymer and coagulating; And
A method for producing a graft copolymer, which comprises emulsion-polymerizing an aggregated diene polymer, an aromatic vinyl monomer and a vinylcyanide monomer. The method according to claim 1,
Wherein the polymer flocculant is an alkyl acrylate derived unit; And a unit derived from at least one of (meth) acrylic acid and (meth) acrylamide. 3. The method of claim 2,
Wherein the polymer flocculant is a unit derived from at least one of ethyl acrylate and butyl acrylate; And a unit derived from at least one of meth (acrylic acid) and meth (acrylamide). The method according to claim 1,
Wherein the polymer flocculant has an average particle diameter of 1200 to 1600 ANGSTROM. The method according to claim 1,
Wherein the polymer flocculant is added in an amount of 1 to 10 parts by weight based on 100 parts by weight of the diene polymer. The method according to claim 1,
The polymer flocculant is a core-shell structure, and based on the total weight of the core and shell,
30 to 75% by weight of cores; And
And 25 to 70% by weight of the shell. The method according to claim 6,
Wherein the core comprises less than 10% by weight of meth (acrylic acid) derived units. The method according to claim 6,
Wherein the shell comprises 10 to 20 wt% of a unit derived from math (acrylic acid). The method according to claim 1,
Wherein the pre-agglomerated diene polymer has an average particle diameter of 800 to 1200 ANGSTROM. The method according to claim 1,
Wherein the aggregated diene-based polymer has an average particle diameter of 1400 to 4500 angstroms. The method according to claim 1,
Wherein the aggregated diene-based polymer has an average particle diameter of 3200 to 3500 angstroms. The method according to claim 1,
Wherein the rate of change of the average particle diameter of the coagulated diene-based polymer is maintained within a range of 0.005 to 0.05%. The method according to claim 1,
Wherein the standard deviation measured by a particle size analyzer NICOMP 380 software in the particle size distribution (PSD) of the coagulated diene polymer is less than 0.45. The method according to claim 1,
In the emulsion polymerization step, based on the total weight of the diene polymer, the aromatic vinyl monomer and the vinylcyanide monomer,
The diene polymer is 20 to 70% by weight,
The content of the aromatic vinyl monomer is 0.1 to 40% by weight,
And the vinyl cyano monomer is 0.1 to 40% by weight.