KR102412417B1 - Method for graft copolymer and graft copolymer - Google Patents

Abstract

The present invention relates to a method for producing a graft copolymer in which silica nanopowder, a conjugated diene-based polymer, an aromatic vinyl-based monomer and a vinyl cyan-based monomer are added and polymerized, and a graft copolymer having a remarkably low coefficient of thermal expansion can be prepared While possible, the manufacturing method can be simplified.

Description

Method for producing a graft copolymer and a graft copolymer

[Citation with related applications]

The present invention claims the benefit of priority based on Korean Patent Application No. 10-2017-0083682 filed on June 30, 2017, and includes all contents disclosed in the literature of the Korean patent application as a part of this specification.

[Technical field]

The present invention relates to a method for preparing a graft copolymer and a graft copolymer, and more particularly, to a method for preparing a graft copolymer including silica nanopowder and to a graft copolymer.

The ABS graft copolymer can be prepared by dissolving butadiene polymer in a solvent together with acrylonitrile and styrene to perform bulk polymerization, and by emulsion polymerization of acrylonitrile and styrene to butadiene polymer latex prepared by emulsion polymerization.

Among them, the ABS graft copolymer prepared by emulsion polymerization has a high manufacturing cost, so it is mixed with a SAN copolymer prepared by suspension polymerization or bulk polymerization of styrene and acrylonitrile and used in the form of a thermoplastic resin composition. The thermoplastic resin composition may be prepared into various types of products depending on the monomer composition and molecular weight of the SAN copolymer and may have excellent surface gloss.

Such a thermoplastic resin composition may be manufactured into a product by being injected under high temperature and high pressure conditions and then cooled at room temperature and pressure conditions. However, the overall volume of the thermoplastic resin composition is excessively contracted during this molding process, and as a result, the appearance of the product is deformed and warpage occurs, thereby reducing dimensional stability.

Accordingly, research to improve the dimensional stability of the thermoplastic resin molded article by improving the shrinkage problem of the thermoplastic resin composition during the molding process continues.

KR2017-0062888A

It is an object of the present invention to provide a method for preparing a graft copolymer having a low thermal expansion coefficient, while the method for preparing a graft copolymer is simple.

In order to solve the above problems, the present invention provides a method for preparing a graft copolymer in which silica nanopowder, a conjugated diene-based polymer, an aromatic vinyl-based monomer, and a vinyl cyan-based monomer are added and polymerized.

In addition, the present invention is silica; conjugated diene-based polymers; an aromatic vinyl-based monomer-derived unit; And it provides a graft copolymer comprising a vinyl cyan-based monomer-derived unit.

In addition, the present invention is the graft copolymer; and an aromatic vinyl-based monomer-derived unit and a copolymer comprising a vinyl cyan-based monomer-derived unit, and provides a thermoplastic resin molded article having a thermal expansion coefficient of 200 × 10 ^-6 K ^-1 or less.

In the method for preparing the graft copolymer according to the present invention, since silica nanopowder, which is easy to store and handle, is added, the manufacturing process can be simplified.

In addition, the graft copolymer according to the present invention has not only a low coefficient of thermal expansion, but also excellent basic physical properties such as reflective haze, impact strength and surface gloss.

Hereinafter, the present invention will be described in more detail to help the understanding of the present invention.

The terms or words used in the present specification and claims should not be construed as being limited to their ordinary or dictionary meanings, and the inventor may properly define the concept of the term in order to best describe his invention. Based on the principle that there is, it should be interpreted as meaning and concept consistent with the technical idea of the present invention.

In the present invention, the average particle diameter of the silica nanopowder can be measured using a dynamic light scattering method, and specifically, after ultrasonic grinding is performed on the silica nanoparticle suspension for 10 minutes, Zetaplus (trade name, manufacturer) at room temperature : Brookhaven Instruments Corporation, NY, USA).

In the present specification, the average particle diameter of the silica nanopowder means the arithmetic average particle diameter in the particle size distribution measured by the dynamic light scattering method. The arithmetic mean particle diameter can be measured as the average particle diameter of the scattering intensity (Intensity Distribution), the average particle diameter of the volume (Volume Distribution), and the average particle diameter of the number (Number Distribution). Of these, it is preferable to measure the average particle diameter of the scattering intensity.

In the present invention, the coefficient of thermal expansion means a value obtained by converting the rate of expansion due to heat under a constant pressure per unit temperature. The rate of expansion and contraction is an intrinsic property of a material constituting an object, and thermal contraction and expansion of a material occurs due to a difference in density of the material according to temperature.

In the present invention, the coefficient of thermal expansion may be measured according to ASTM D696.

In the present invention, the weight average molecular weight of the shell of the graft copolymer is dissolved 1 g of the graft copolymer powder in 50 g of acetone while stirring for 24 hours, then put into a centrifuge set at 20,000 rpm and -20 ° C., and the supernatant is separated After drying the precipitate in a hot air oven at 50° C., it is dissolved in a THF solution to prepare a solution (concentration: 0.1 wt %), and after filtering it through a 0.1 μm filter, finally using a GPC device (manufacturer: waters) can be measured

The average particle diameter of the particles of the conjugated diene-based polymer in the present invention can be measured using a dynamic light scattering (dynamic light scattering) method, specifically, Nicomp 380 equipment (product name, manufacturer: PSS) can be measured using.

In the present specification, the average particle diameter of the conjugated diene-based polymer means the arithmetic average particle diameter in the particle size distribution measured by the dynamic light scattering method. The arithmetic mean particle diameter can be measured as the average particle diameter of the scattering intensity (Intensity Distribution), the average particle diameter of the volume (Volume Distribution), and the average particle diameter of the number (Number Distribution). Of these, it is preferable to measure the average particle diameter of the scattering intensity.

One. graft Method for preparing copolymer

The graft copolymer according to an embodiment of the present invention is polymerized by adding silica nanopowder, a conjugated diene-based polymer, an aromatic vinyl-based monomer, and a vinyl cyan-based monomer.

The thermal expansion coefficient of the silica nanopowder is 1 × 10 ^-8 to 100 × 10 ^-8 K ^-1 , and a graft copolymer including a conjugated diene-based polymer, an aromatic vinyl-based monomer-derived unit, and a vinyl cyan-based monomer-derived unit. The coefficient of thermal expansion is 300 × 10 ^-6 to 400 × 10 ^-6 K ^-1 . Accordingly, when silica nanopowder is added during the manufacturing process of the graft copolymer, the silica nanopowder is not only included in the graft copolymer, but also can be uniformly distributed, thereby significantly lowering the thermal expansion coefficient of the graft copolymer. .

In the conventional thermoplastic resin composition including the graft copolymer, the energy of the chain molecules in the thermoplastic resin composition is lowered during the molding process of cooling at room temperature and pressure after injection under high temperature and high pressure conditions, thereby reducing the distance between the chain molecules. The density of the resin composition was increased. As the density of the thermoplastic resin composition increases, a problem in that the overall volume of the thermoplastic resin molded article is contracted has occurred.

However, the thermoplastic resin composition including the graft copolymer containing silica nanopowder minimizes the decrease in the distance between chain molecules in the thermoplastic resin composition during the molding process, so that the density change of the thermoplastic resin composition can be minimized, and as a result, The occurrence of deformation and warpage of the thermoplastic resin molded article may be reduced, and thus dimensional stability may be improved.

The silica nanopowder is a compound having a lattice structure of silicon and oxygen, silicon dioxide (SiO ₂ ), silica gel, or silicon oxide (SiO _x , 0<x<2) in which silicon is distributed in a silicon dioxide (SiO ₂ ) matrix. It may exist in the form of this nanopowder.

The silicon dioxide may be in a crystalline, amorphous or free state.

The silicon oxide may be SiO _x (0<x≤1), for example, SiO. Silicon in the silicon oxide (SiO _x , 0<x<2) may be amorphous or crystalline. When silicon in the silicon oxide (SiO _x , 0<x<2) is crystalline, the size of the crystal may be greater than 0 and less than 30 nm.

The silica nanopowder may be prepared by the Stober method. Specifically, the silica nanopowder is obtained by reacting tetraethyl orthosilicate (TEOS) with water and alcohol under a NH ₃ catalyst to obtain colloidal silica containing spherical silica having a uniform nano size, followed by drying to obtain a solvent. It can be prepared after removal.

On the other hand, colloidal silica is dispersed in a state in which solid silica particles are not precipitated or aggregated in a liquid such as water or an organic solvent, and in order to maintain the colloidal state, it is necessary to maintain an appropriate pH. However, if an appropriate pH is not maintained, colloidal silica is precipitated or aggregated due to a decrease in dispersing power, so the thermal expansion coefficient of the graft copolymer cannot be lowered, and the surface gloss property is also reduced.

However, since the silica nanopowder is a solid, it is easy to store and handle, and can be simply added when preparing the graft copolymer. In addition, the thermal expansion coefficient, reflection haze, and impact strength of a thermoplastic resin molded article, which is a final product, may be superior to that in the case of injecting colloidal silica by injecting silica nanopowder.

Meanwhile, the silica nanopowder may have an average particle diameter of 10 to 150 nm, 10 to 100 nm, or 10 to 50 nm, of which 10 to 50 nm is preferable.

If the above-mentioned conditions are satisfied, a graft copolymer in which silica nanopowder is uniformly distributed can be prepared, thereby lowering the thermal expansion coefficient of the graft copolymer, and basic physical properties, that is, reflective haze, impact strength and surface The deterioration of gloss can be prevented.

The silica nanopowder may be added in an amount of 0.01 to 2 parts by weight, 0.05 to 1 part by weight, or 0.1 to 0.5 parts by weight, based on 100 parts by weight of the total of the conjugated diene-based polymer, the aromatic vinyl-based monomer and the vinyl cyan-based monomer, Among them, 0.1 to 0.5 parts by weight is preferably added.

If the above-mentioned conditions are satisfied, a graft copolymer in which silica nanopowder is uniformly distributed can be prepared, thereby lowering the thermal expansion coefficient of the graft copolymer, and basic physical properties, that is, reflective haze, impact strength and surface The deterioration of gloss can be prevented.

The silica nanopowder may be surface-modified to improve dispersibility, mechanical properties, water resistance and reinforcing properties. The silica nanopowder may be surface-modified with at least one selected from the group consisting of a hydroxyl group (OH), a polystyrene-based resin, and a polyethylene-based resin.

The conjugated diene-based polymer is a conjugated diene-based polymer; a copolymer comprising a unit derived from a conjugated diene-based monomer and a unit derived from an aromatic vinyl-based monomer; or a mixture thereof. The conjugated diene-based polymer may be in the form of a latex, and may be prepared by emulsion polymerization.

The conjugated diene-based monomer-derived unit may be one or more derived units selected from the group consisting of 1,3-butadiene, isoprene, chloroprene and piperylene, among which, 1,3-butadiene-derived units are preferred.

The aromatic vinyl-based monomer-derived unit may be at least one derived unit selected from the group consisting of styrene, α-methyl styrene, α-ethyl styrene, and p-methyl styrene, and among these, styrene-derived units are preferable.

When the conjugated diene-based polymer is a mixture, the weight ratio of the conjugated diene-based polymer to a copolymer including a unit derived from a conjugated diene-based monomer and a unit derived from an aromatic vinyl-based monomer is 30:70 to 50:50 or 30:70 to 40 : 60, preferably 30:70 to 40:60.

The conjugated diene-based polymer may have an average particle diameter of 0.2 to 0.6 μm, 0.2 to 0.5 μm, or 0.2 to 0.35 μm, of which 0.2 to 0.35 μm is preferable.

When the above-described range is satisfied, the surface gloss, color, and mechanical properties of the graft copolymer may all be excellent.

The gel content of the conjugated diene-based polymer may be 60 to 98%, specifically 65 to 90%, and more specifically 70 to 85%.

The conjugated diene-based polymer may be added in an amount of 40 to 70% by weight, 45 to 65% by weight, or 50 to 60% by weight, based on the total weight of the conjugated diene-based polymer, the aromatic vinyl-based monomer and the vinyl cyan-based monomer, Among them, it is preferably added in an amount of 50 to 60% by weight.

When the above-mentioned range is satisfied, the surface gloss and mechanical properties of the graft copolymer can be further improved.

The type of the aromatic vinyl-based monomer is the same as described above.

The aromatic vinyl-based monomer may be added in an amount of 20 to 40% by weight, 25 to 35% by weight, or 30 to 35% by weight based on the total weight of the conjugated diene-based polymer, the aromatic vinyl-based monomer and the vinyl cyan-based monomer, Among them, it is preferably added in an amount of 30 to 35% by weight.

When the above-mentioned range is satisfied, the rigidity, impact resistance and processability of the graft copolymer can be further improved.

The vinyl cyan-based monomer is selected from the group consisting of acrylonitrile, methacrylonitrile, ethacrylonitrile, phenylacrylonitrile, α-chloronitrile, α-chloroacrylonitrile and α-cyanoethylacrylonitrile and may be one or more of them, and among them, acrylonitrile is preferable.

The vinyl cyan-based monomer may be added in an amount of 1 to 30 wt%, 5 to 25 wt%, or 5 to 15 wt%, based on the total weight of the conjugated diene-based polymer, the aromatic vinyl-based monomer and the vinyl cyan-based monomer, Among them, it is preferably added in an amount of 5 to 15% by weight.

If the above-described range is satisfied, the chemical resistance of the graft copolymer may be further improved.

On the other hand, in the method for producing a graft copolymer according to an embodiment of the present invention, it is preferable to polymerize while continuously injecting the silica nanopowder at a constant rate.

When the silica nanopowder is continuously added and polymerized, the silica nanopowder is more uniformly distributed in the graft copolymer, so that uniform physical properties can be realized in the entire region of the graft copolymer.

When the silica nanopowder is continuously added, it is preferable to polymerize while continuously adding the conjugated diene-based polymer, the aromatic vinyl-based monomer, and the vinyl cyan-based monomer at a constant rate.

The method for preparing the graft copolymer according to an embodiment of the present invention may use emulsion polymerization, and when the graft copolymer is prepared by emulsion polymerization, a graft copolymer having excellent surface gloss properties and mechanical properties can be prepared. can

In the method for producing a graft copolymer according to an embodiment of the present invention, it is preferable to further add at least one selected from the group consisting of an initiator, a redox catalyst, an emulsifier, a molecular weight regulator, and ion-exchanged water.

In addition, it is preferable that the initiator and the like be continuously added at a constant rate together with the above-described silica nanopowder. When the initiator or the like is continuously added, it may be easy to control heat generation.

The initiator may be at least one selected from the group consisting of a water-soluble polymerization initiator and a fat-soluble polymerization initiator.

The water-soluble polymerization initiator may be at least one selected from the group consisting of potassium persulfate, sodium persulfate and ammonium persulfate.

The fat-soluble polymerization initiator may be at least one selected from the group consisting of cumene hydroperoxide, diisopropyl benzene hydroperoxide, azobis isobutylnitrile, t-butyl hydroperoxide, paramethane hydroperoxide and benzoyl peroxide. and among them, t-butyl hydroperoxide is preferred.

The initiator may be added in an amount of 0.1 to 1.0 parts by weight, 0.1 to 0.5 parts by weight, or 0.1 to 0.3 parts by weight, based on 100 parts by weight of the total of the conjugated diene-based polymer, the aromatic vinyl-based monomer, and the vinyl cyan-based monomer, of which It is preferably added in an amount of 0.1 to 0.3 parts by weight.

When the above-described range is satisfied, polymerization is easily initiated, and the polymerization conversion rate of the graft copolymer may be increased even if the polymerization time is not increased.

The redox catalyst may be at least one selected from the group consisting of sodium formaldehyde sulfoxylate, sodium ethylenediamine tetraacetate, ferrous sulfate, dextrose, sodium pyrophosphate, anhydrous sodium pyrophosphate and sodium sulfate, It is preferably at least one selected from the group consisting of ferrous sulfate, dextrose and sodium pyrophosphate.

The redox catalyst may be added in an amount of 0.01 to 1.5 parts by weight or 0.03 to 1.0 parts by weight based on 100 parts by weight of the total of the conjugated diene-based polymer, the aromatic vinyl-based monomer, and the vinyl cyan-based monomer, of which 0.03 to 1.0 It is preferably added in parts by weight.

When the above-mentioned range is satisfied, polymerization can be easily initiated at a relatively low temperature.

The emulsifier is allyl aryl sulfonate, alkali metal alkyl sulfate, sulfonated alkyl ester, C6-C22 fatty acid, alkali metal rosin acid salt, sodium lauryl sulfonate, potassium oleate, sodium alkylbenzene sulfonate, polyoxyethylene alkylphenyl ether, sodium dodecyl allyl sulfosuccinate, C16-18 alkenyl succinic acid di-potassium salt, sodium acrylamidostearate, polyoxyethylene alkylphenylether ammonium sulfate and polyoxyethylene alkylether ester ammonium salt and may be one or more, among which C6-C22 fatty acids are preferred.

The emulsifier may be added in an amount of 0.01 to 10 parts by weight, 0.1 to 5 parts by weight, or 0.2 to 2 parts by weight, based on 100 parts by weight of the total of the conjugated diene-based polymer, the aromatic vinyl-based monomer and the vinyl cyan-based monomer, It is preferably added in 0.2 to 2 parts by weight.

When the above-mentioned range is satisfied, the polymerization may be stably performed, and the surface gloss and mechanical properties of the graft copolymer may be improved.

The molecular weight modifier is α-methyl styrene dimer, t-dodecyl mercaptan, n-dodecyl mercaptan, octyl mercaptan, carbon tetrachloride, methylene chloride, methylene bromide, tetraethyl thiuram di sulfide, dipentamethylene thiuram di sulfide. , and may be at least one selected from the group consisting of diisopropyl xantogen disulfide, of which t-dodecyl mercaptan is preferable.

The molecular weight modifier may be added in an amount of 0.1 to 1.0 parts by weight, 0.1 to 0.8 parts by weight, or 0.1 to 0.5 parts by weight, based on 100 parts by weight of the total of the conjugated diene-based polymer, the aromatic vinyl-based monomer and the vinyl cyan-based monomer, It is preferably added in an amount of 0.1 to 0.5 parts by weight.

When the above-mentioned range is satisfied, the weight average molecular weight of the shell of the graft copolymer can be properly maintained, and the residual amount in the graft copolymer can be minimized.

The polymerization may be carried out at 60 to 80 ℃ or 65 to 75 ℃, of which it is preferably carried out at 65 to 75 ℃. In addition, the polymerization is preferably carried out at a constant temperature.

If the above-described temperature is satisfied, heat generation can be easily controlled and mechanical properties can be optimized.

On the other hand, during the polymerization, additives, specifically, at least one selected from the group consisting of a chelating agent, a dispersing agent, a pH adjusting agent, an oxygen scavenger, an anti-aging agent, an electrolyte, and an oxygen scavenger, are added to facilitate polymerization can be

The method for producing a graft copolymer according to an embodiment of the present invention may further include the step of aging.

The aging may be performed after raising the temperature of the reactor, or may be performed after adding an initiator and a redox catalyst to the polymer and raising the temperature of the reactor.

The aging may be performed at a higher temperature than polymerization, preferably at 70 to 90 °C or 75 to 85 °C, more preferably at 75 to 85 °C.

When the above-mentioned conditions are satisfied, the aggregation phenomenon between the monomers and additives added during polymerization is reduced, so that the stability of the polymer can be improved.

After the aging is completed, agglomeration and drying may be further performed.

The agglomeration may be a process of agglomeration by adding an acid or inorganic salt aqueous solution to the graft copolymer latex in order to aggregate the polymerized graft copolymer latex.

The agglomeration may be a process for removing impurities (residual emulsifier, etc.) from the graft copolymer latex and obtaining a graft copolymer in powder form. Specifically, it can be carried out by adding the graft copolymer latex to an acid or an aqueous inorganic salt solution and agglomeration, followed by drying.

At this time, the aggregation is not particularly limited and may be performed by a conventional method in the art, but specifically, the agglomeration is performed by heating the acid or inorganic salt aqueous solution to 50 to 60° C., and then the graft copolymer latex. It can be carried out by adding and stirring for 10 minutes to 1 hour.

The acid may be sulfuric acid, and the inorganic salt may be at least one selected from the group consisting of potassium chloride, sodium chloride, manganese chloride, calcium chloride, magnesium sulfate and aluminum sulfate, of which calcium chloride is preferable.

The drying is to remove moisture remaining in the agglomerated graft copolymer, and may be performed at 100 to 140 °C or 100 to 120 °C, of which it is preferably performed at 100 to 120 °C.

If the above-described temperature is satisfied, thermal deformation can be prevented while the graft copolymer is sufficiently dried.

2. graft copolymer

The graft copolymer prepared according to another embodiment of the present invention is silica; conjugated diene-based polymers; an aromatic vinyl-based monomer-derived unit; and a vinyl cyan-based monomer-derived unit.

The silica is derived from the silica nanopowder, is uniformly distributed in the graft copolymer, and can significantly lower the thermal expansion coefficient of the graft copolymer.

The silica may be included in an amount of 0.001 to 1.5 wt%, 0.09 to 1.0 wt%, or 0.1 to 1.0 wt%, based on the total weight of the graft copolymer, of which 0.1 to 1.0 wt% is preferable.

If the above conditions are satisfied, the thermal expansion coefficient of the graft copolymer is significantly lowered, and the basic physical properties of the graft copolymer are not negatively affected.

The silica may have an average particle diameter of 10 to 150 nm, 10 to 100 nm, or 10 to 50 nm, of which 10 to 50 nm is preferable.

If the above-mentioned conditions are satisfied, a graft copolymer in which silica is uniformly distributed can be prepared, which lowers the thermal expansion coefficient of the graft copolymer, and improves basic physical properties, porridge, reflective haze, impact strength, and surface gloss. degradation can be prevented.

In addition, the description of the silica is the same as described in the description of the silica nanopowder in the manufacturing method of the graft copolymer.

The conjugated diene-based polymer may be included in an amount of 40 to 70% by weight, 45 to 65% by weight, or 50 to 60% by weight, of which 50 to 60% by weight, based on the total weight of the graft copolymer. desirable.

When the above-mentioned range is satisfied, the surface gloss and mechanical properties of the graft copolymer can be further improved.

The aromatic vinyl-based monomer-derived unit may be added in an amount of 20 to 40% by weight, 25 to 35% by weight, or 30 to 35% by weight, of which 30 to 35% by weight, based on the total weight of the graft copolymer. It is preferable to input.

When the above-mentioned range is satisfied, the rigidity, impact resistance and processability of the graft copolymer can be further improved.

The vinyl cyan-based monomer-derived unit may be added in an amount of 1 to 30% by weight, 5 to 25% by weight, or 5 to 15% by weight, of which 5 to 15% by weight, based on the total weight of the graft copolymer. It is preferable to input.

If the above-described range is satisfied, the chemical resistance of the graft copolymer may be further improved.

In addition, the description of the conjugated diene-based polymer, the aromatic vinyl-based monomer-derived unit and the vinyl cyan-based monomer-derived unit is for the conjugated diene-based polymer, the aromatic vinyl-based monomer and the vinyl cyan-based monomer in the method for preparing the graft copolymer. As described in the description.

In addition, the graft copolymer may have a shell weight average molecular weight of 50,000 to 400,000 g/mol, 60,000 to 200,000 g/mol, or 70,000 to 100,000 g/mol, of which 70,000 to 100,000 g/mol is preferable.

In addition, the graft copolymer may have a glass transition temperature of 90 to 130 °C, 90 to 120 °C, or 90 to 115 °C.

When the above-described conditions are satisfied, the heat resistance of the graft copolymer may be improved, and process efficiency may be increased during molding of the thermoplastic resin composition including the graft copolymer.

3. Thermoplastic resin molded products

A thermoplastic resin molded article according to another embodiment of the present invention is a graft copolymer according to another embodiment of the present invention; and a copolymer including a unit derived from an aromatic vinyl-based monomer and a unit derived from a vinyl cyan-based monomer, and has a coefficient of thermal expansion of 200 × 10 ^-6 K ^-1 or less.

The coefficient of thermal expansion is preferably 170 × 10 ^-6 to 200Х10 ^-6 K ^-1 .

When the above conditions are satisfied, the dimensional stability of the thermoplastic resin molded article may be further improved.

The copolymer may include an aromatic vinyl-based monomer-derived unit and a vinyl cyan-based monomer-derived unit in a weight ratio of 80:20 to 65:35 or 75:25 to 70:30, of which 75:25 to 70:30 It is preferable to include it in a weight ratio of

When the above-mentioned range is satisfied, a balance of mechanical properties, processability, and heat resistance may be well achieved.

The description of the aromatic vinyl-based monomer-derived unit and the vinyl cyan-based monomer-derived unit is the same as described above in the description of the aromatic vinyl-based monomer and the vinyl cyan-based monomer, except that the unit is a monomer-derived unit.

The weight ratio of the graft copolymer to the copolymer may be 20:80 to 35 to 65 or 25:75 to 30:70, of which 25:75 to 30:70 is preferable.

When the above-mentioned range is satisfied, the coefficient of thermal expansion, mechanical properties, and surface properties of the molded article made of the thermoplastic resin composition may be further improved.

Hereinafter, embodiments of the present invention will be described in detail so that those of ordinary skill in the art can easily carry out the present invention. However, the present invention may be embodied in several different forms and is not limited to the embodiments described herein.

< graft Preparation of Copolymer>

Example One

0.05 parts by weight of silica nanopowder having an average particle diameter of 20 nm, 60 parts by weight of butadiene polymer (average particle diameter: 0.3 μm), 30 parts by weight of styrene, 10 parts by weight of acrylonitrile, 125 parts by weight of ion-exchanged water, 0.12 parts by weight of t-butyl hydroperoxide as an initiator, 0.7 parts by weight of C18 fatty acid as an emulsifier, 0.35 parts by weight of t-dodecylmercaptan as a molecular weight regulator, 0.054 parts by weight of dextrose as a redox catalyst, Polymerization was carried out while continuously adding 0.002 parts by weight of ferrous sulfate and 0.004 parts by weight of sodium pyrophosphate at a constant rate for 3 hours.

Then, 0.05 parts by weight of t-butyl hydroperoxide, 0.05 parts by weight of dextrose, 0.03 parts by weight of sodium pyrophosphate, and 0.001 parts by weight of ferrous sulfate were put into the polymerization reactor at once, and then, while raising the temperature to 80 ° C. over 1 hour After polymerization, the reaction was terminated to prepare a graft copolymer latex. At this time, the polymerization conversion rate was 95%.

Then, the graft copolymer latex was aggregated with an aqueous sulfuric acid solution, and then aged, washed and dried to prepare a powdery graft copolymer.

Example 2

A graft copolymer (polymerization conversion: 95%) was prepared in the same manner as in Example 1, except that 0.10 parts by weight of silica nanopowder having an average particle diameter of 20 nm was added.

Example 3

A graft copolymer (polymerization conversion: 95%) was prepared in the same manner as in Example 1, except that 1 part by weight of silica nanopowder having an average particle diameter of 20 nm was added.

Example 4

A graft copolymer (polymerization conversion: 95%) was prepared in the same manner as in Example 3, except that silica nanoparticles having an average particle diameter of 10 nm were added instead of silica nanoparticles having an average particle diameter of 20 nm.

Example 5

A graft copolymer (polymerization conversion rate: 95%) was prepared in the same manner as in Example 3, except that silica nanoparticles having an average particle diameter of 30 nm were added instead of silica nanoparticles having an average particle diameter of 20 nm.

Example 6

A graft copolymer (polymerization conversion rate: 95%) was prepared in the same manner as in Example 3, except that silica nanoparticles having an average particle diameter of 50 nm were added instead of silica nanoparticles having an average particle diameter of 20 nm.

Example 7

A graft copolymer (polymerization conversion: 95%) was prepared in the same manner as in Example 3, except that silica nanoparticles having an average particle diameter of 70 nm were added instead of silica nanoparticles having an average particle diameter of 20 nm.

Example 8

A graft copolymer (polymerization conversion: 95%) was prepared in the same manner as in Example 3, except that silica nanoparticles having an average particle diameter of 100 nm were added instead of silica nanoparticles having an average particle diameter of 20 nm.

Example 9

A graft copolymer (polymerization conversion: 95%) was prepared in the same manner as in Example 3, except that silica nanoparticles having an average particle diameter of 150 nm were added instead of silica nanoparticles having an average particle diameter of 20 nm.

Example 10

A graft copolymer was prepared in the same manner as in Example 3, except that silica nanoparticles having an average particle diameter of 200 nm were added instead of silica nanoparticles having an average particle diameter of 20 nm.

Example 11

A graft copolymer (polymerization conversion: 94%) was prepared in the same manner as in Example 1, except that 0.10 parts by weight of silica nanopowder having an average particle diameter of 20 nm was collectively added.

comparative example One

A graft copolymer (polymerization conversion: 95%) was prepared in the same manner as in Example 1, except that silica nanopowder was not added.

comparative example 2

A graft copolymer (polymerization conversion rate: 94%) was prepared in the same manner as in Example 2, except that colloidal silica containing silica having an average particle diameter of 20 nm was added instead of silica nanopowder having an average particle diameter of 20 nm. did

comparative example 3

A graft copolymer (polymerization conversion rate: 94%) was prepared in the same manner as in Example 11, except that colloidal silica containing silica having an average particle diameter of 20 nm was batch-injected instead of silica nanopowder having an average particle diameter of 20 nm. prepared.

Hereinafter, the type, average particle diameter, input method and input amount of silica input in Examples and Comparative Examples are summarized and described in Table 1 below.

division silica shape Average particle diameter (nm) Input method Input amount (parts by weight) Example 1 Silica Nanopowder 20 continuous input 0.05 Example 2 Silica Nanopowder 20 continuous input 0.10 Example 3 Silica Nanopowder 20 continuous input 1.00 Example 4 Silica Nanopowder 10 continuous input 0.10 Example 5 Silica Nanopowder 30 continuous input 0.10 Example 6 Silica Nanopowder 50 continuous input 0.10 Example 7 Silica Nanopowder 70 continuous input 0.10 Example 8 Silica Nanopowder 100 continuous input 0.10 Example 9 Silica Nanopowder 150 continuous input 0.10 Example 10 Silica Nanopowder 200 continuous input 0.10 Example 11 Silica Nanopowder 20 batch input 0.10 Comparative Example 1 - - - - Comparative Example 2 colloidal silica 20 continuous input 0.10 Comparative Example 3 colloidal silica 20 batch input 0.10

※Colloidal silica: silica (SiO ₂ ) 50% by weight (manufactured by LG Chem)

Experimental example

A thermoplastic resin composition was prepared by uniformly mixing 27.5 parts by weight of the graft copolymer of Examples and Comparative Examples and 72.5 parts by weight of the SAN copolymer (trade name: 92HR, manufacturer: LG Chem). After the thermoplastic resin composition was extruded and pelletized, a thermoplastic resin specimen was prepared by injection at 270°C.

The physical properties of the thermoplastic resin specimen were measured by the following method, and the results are shown in Table 2 below.

① Coefficient of Thermal Expansion (K ^-1 ): Measured according to ASTM D696 , and calculated by substituting into Equation 1 below.

<Equation 1>

σ = average coefficient of thermal expansion

L0 = initial length of the specimen

ΔL = change in specimen length

ΔT = specimen temperature bias

② Reflection Haze: Measured using 512 diodes arranged in a straight line profiling the reflected light in a large arc from 14° to 27° using the Rhopoint IQ device. It was calculated by Equation 2 below at an angle of 20°.

<Equation 2>

③ Impact strength (kg·cm/cm, 1/4 in): Measured according to ASTM D256.

④ Surface gloss (%): It was measured at 45° according to ASTM D528.

division CTE (K ^-1 ) reflection haze impact strength
(kg cm/cm) Surface gloss (%) Example 1 197×10 ^-6 5.2 32 89.4 Example 2 192×10 ^-6 5.5 31 89.1 Example 3 190×10 ^-6 6.4 27 85.2 Example 4 195×10 ^-6 5.2 29 89.4 Example 5 193×10 ^-6 5.7 31 88.9 Example 6 192×10 ^-6 5.9 30 88.5 Example 7 192×10 ^-6 6.4 29 88.1 Example 8 193×10 ^-6 6.6 29 87.6 Example 9 193×10 ^-6 6.8 29 86.2 Example 10 192×10 ^-6 7.2 24 82.1 Example 11 203×10 ^-6 7.1 25 83.4 Comparative Example 1 345×10 ^-6 5.0 29 89.4 Comparative Example 2 220×10 ^-6 5.7 30 89.2 Comparative Example 3 262×10 ^-6 7.2 26 84.1

As shown in Table 2, in Examples 1 to 11 in which silica nanoparticles were added, it was confirmed that the coefficient of thermal expansion was remarkably improved compared to Comparative Example 1 in which silica nanoparticles were not added.

Comparing Examples 1 to 3, it was confirmed that the thermal expansion characteristics were improved because the thermal expansion coefficient decreased as the amount of the added silica nanopowder was increased.

Comparing Examples 2 and 4 to 10, even if the average particle diameter of the injected silica nanoparticles increases, the coefficient of thermal expansion realizes the same level, so the average particle diameter of the silica nanoparticles does not affect the thermal expansion characteristics could confirm that However, when the average particle diameter of the silica nanopowder was 30 nm or more, the higher the average particle diameter, the higher the reflection haze and the lower the surface gloss. In addition, when the average particle diameter of the silica nanopowder was 50 nm or more, the impact strength decreased as the average particle diameter increased. From these results, it was confirmed that the average particle diameter of the silica nanopowder affects the basic physical properties of the thermoplastic resin molded article.

Comparing Example 1 and Example 11, it was confirmed that when silica nanopowder was continuously added, the coefficient of thermal expansion and reflection haze were lowered, and impact strength and surface gloss were improved.

On the other hand, Example 1 and Comparative Example 2 were different only in the form of silica input, but it was confirmed that Example 1 was superior to Comparative Example 2 in terms of coefficient of thermal expansion, reflection haze, impact strength and surface gloss. Example 11 and Comparative Example 3 also differ only in the form of silica input, but Example 11 was superior to Comparative Example 3 in the coefficient of thermal expansion and surface gloss, and it was confirmed that the reflective haze and impact strength were at the same level. That is, it was confirmed that the nanopowder form not only facilitates storage and handling compared to the colloidal form, but also significantly affects the improvement of the overall physical properties of the thermoplastic resin.

Claims (10)

A method for producing a graft copolymer in which silica nanopowder, a conjugated diene-based polymer, an aromatic vinyl-based monomer and a vinyl cyan-based monomer are continuously added and polymerized.
The method according to claim 1,
The silica nanopowder is a method for producing a graft copolymer having an average particle diameter of 10 to 150 nm.
The method according to claim 1,
The silica nanopowder is a method of producing a graft copolymer that is added in an amount of 0.01 to 2.0 parts by weight based on 100 parts by weight of the total of the conjugated diene-based polymer, the aromatic vinyl-based monomer and the vinyl cyan-based monomer.
The method according to claim 1,
Based on the total weight of the conjugated diene-based polymer, the aromatic vinyl-based monomer and the vinyl cyan-based monomer,
40 to 70% by weight of the conjugated diene-based polymer;
20 to 40 wt% of the aromatic vinyl-based monomer; and
The method for producing a graft copolymer that is added in 1 to 30% by weight of the vinyl cyanide-based monomer.
delete The method according to claim 1,
The polymerization is an emulsion polymerization method for producing a graft copolymer.
delete delete delete delete