METHOD OF PREPARING GRAFT POLYMER

Abstract

Provided is a method of preparing a graft polymer, which includes: adding a diene-based rubber polymer, a first monomer mixture including a (meth)acrylate-based monomer and an aromatic vinyl-based monomer, and a reactive ultraviolet (UV) stabilizer to a reactor and carrying out polymerization to prepare a composite rubber polymer; and graft-polymerizing a second monomer mixture including a (meth)acrylate-based monomer, an aromatic vinyl-based monomer, and a vinyl cyanide-based monomer to the composite rubber polymer to prepare a graft polymer, wherein the reactive UV stabilizer is added in an amount of 0.1 to 2 parts by weight based on 100 parts by weight of the sum of the diene-based rubber polymer, the first monomer mixture, and the second monomer mixture.

Claims

1. A method of preparing a graft polymer, comprising: adding a diene-based rubber polymer, a first monomer mixture including a (meth)acrylate-based monomer and an aromatic vinyl-based monomer, and a reactive ultraviolet (UV) stabilizer to a reactor and carrying out polymerization to prepare a composite rubber polymer; and graft-polymerizing a second monomer mixture including a (meth)acrylate-based monomer, an aromatic vinyl-based monomer, and a vinyl cyanide-based monomer to the composite rubber polymer to prepare a graft polymer, wherein the reactive ultraviolet (UV) stabilizer is added in an amount of 0.1 to 2 parts by weight based on 100 parts by weight of a sum of the diene-based rubber polymer, the first monomer mixture, and the second monomer mixture.

2. The method of claim 1, wherein the reactive UV stabilizer is added in an amount of 0.5 parts by weight to 1.2 parts by weight based on 100 parts by weight of the sum of the diene-based rubber polymer, the first monomer mixture, and the second monomer mixture.

3. The method of claim 1, wherein the reactive UV stabilizer is a compound represented by the following Chemical Formula 1: ##STR00002## wherein, in Chemical Formula 1, R.sub.1 is hydrogen or a C.sub.1-C.sub.10 linear alkyl group, and L.sub.1 is a direct bond or a C.sub.1-C.sub.10 linear alkylene group.

4. The method of claim 1, wherein the reactive UV stabilizer is one or more selected from the group consisting of 2-[2′-hydroxy-5′-2-(acryloyloxy)phenyl]-2H-benzotriazole, 2-[2′-hydroxy-5′-2-(methacryloyloxy)phenyl]-2H-benzotriazole, 2-[2′-hydroxy-5′-[2-(acryloyloxy)methyl]phenyl]-2H-benzotriazole, 2-[2′-hydroxy-5′-[2-(methacryloyloxy)methyl]phenyl]-2H-benzotriazole, 2-[2′-hydroxy-5′-[2-(acryloyloxy)ethyl]phenyl]-2H-benzotriazole, 2-[2′-hydroxy-5′-[2-(methacryloyloxy)ethyl]phenyl]-2H-benzotriazole, 2-[2′-hydroxy-5′-[2-(acryloyloxy)propyl]phenyl]-2H-benzotriazole, 2-[2′-hydroxy-5′-[2-(methacryloyloxy)propyl]phenyl]-2H-benzotriazole, 2-[2′-hydroxy-5′-[2-(acryloyloxy)butyl]phenyl]-2H-benzotriazole, 2-[2′-hydroxy-5′-[2-(methacryloyloxy)butyl]phenyl]-2H-benzotriazole, 2-[2′-hydroxy-5′-[2-(acryloyloxy)hexyl]phenyl]-2H-benzotriazole, and 2-[2′-hydroxy-5′-[2-(methacryloyloxy)hexyl]phenyl]-2H-benzotriazole.

5. The method of claim 1, wherein, based on 100 parts by weight of the sum of the diene-based rubber polymer, the first monomer mixture, and the second monomer mixture: the diene-based rubber polymer is added in an amount of 7 to 30 parts by weight; the first monomer mixture is added in an amount of 10 to 50 parts by weight; and the second monomer mixture is added in an amount of 20 to 70 parts by weight.

6. The method of claim 1, wherein the diene-based rubber polymer has an average particle diameter of 200 nm to 400 nm.

7. The method of claim 1, wherein the composite rubber polymer has an average particle diameter of 250 nm to 450 nm.

8. The method of claim 1, wherein the graft polymer has a refractive index of 1.51 to 1.52.

Description

PREPARING EXAMPLE 1

[0059] Polymerization was performed while continuously adding a polymerization solution containing 63.36 parts by weight of methyl methacrylate, 24.64 parts by weight of styrene, 12 parts by weight of acrylonitrile, 30 parts by weight of toluene, and 0.15 parts by weight of t-dodecyl mercaptan to a reactor at a constant rate so that the average polymerization time was three hours, and the polymerization temperature was maintained at 148° C. The polymerization product discharged from the reactor was heated in a preheating bath, and unreacted monomers were volatilized in a volatilization bath. Subsequently, the resultant was extruded in an extruder set at 210° C., and thereby a methylstyrene-acrylonitrile (MSAN) polymer (refractive index: 1.516) in pellet form was obtained.

Example 1

[0060] <Preparation of Graft Polymer Powder>

[0061] Polymerization was performed while continuously adding 20 parts by weight(based on solid content) of a butadiene rubber polymer latex (PBL; gel content: 70%, average particle diameter: 300 nm), 24 parts by weight of butyl acrylate (BA), 16 parts by weight of styrene (S), 100 parts by weight of ion-exchanged water, a reactive UV stabilizer (RUVA93 commercially available from Otsuka Chemical Co., Ltd.) in an amount as shown below in Tables, 0.1 parts by weight of cumene hydroperoxide, 0.01 parts by weight of sodium ethylenediaminetetraacetate, 0.04 parts by weight of sodium formaldehyde sulfoxylate, 0.0001 parts by weight of ferrous sulfate, 0.7 parts by weight of sodium dioctyl sulfosuccinate, 0.4 parts by weight of ethylene glycol dimethacrylate, 0.1 parts by weight of allyl methacrylate, and 0.1 parts by weight of NaHCO.sub.3 to a reactor at a constant rate and 70° C. for three hours. Subsequently, after raising the temperature of the reactor to 80° C., polymerization was performed for one hour, and thereby a composite rubber polymer latex was obtained.

[0062] Polymerization was performed while continuously adding 28 parts by weight of methyl methacrylate (MMA), 10 parts by weight of styrene (S), 2 parts by weight of acrylonitrile (AN), 0.1 parts by weight of cumene hydroperoxide, 0.01 parts by weight of sodium ethylenediaminetetraacetate, 0.04 parts by weight of sodium formaldehyde sulfoxylate, 0.001 parts by weight of ferrous sulfate, 0.5 parts by weight of sodium oleate, and 0.4 parts by weight of t-dodecyl mercaptan to the composite rubber polymer latex at a constant rate and 75° C. for five hours. Subsequently, after raising the temperature of the reactor to 80° C., aging was performed for one hour and then polymerization was terminated, and thereby a graft polymer latex was obtained.

[0063] The graft polymer latex was coagulated using an aqueous calcium chloride solution and then aged, washed, dehydrated, and dried, and thereby a graft polymer powder was obtained.

[0064] <Preparation of Thermoplastic Resin Composition>

[0065] Athermoplastic resin composition was prepared by uniformly mixing 35 parts by weight of the graft polymer powder and 65 parts by weight of the MSAN polymer of Preparing Example 1.

Examples 2 to 4

[0066] A graft polymer powder and a thermoplastic resin composition were prepared in the same manner as in Example 1 except that a reactive UV stabilizer (RUVA93 commercially available from Otsuka Chemical Co., Ltd.) was added to a reactor in an amount as shown below in Tables.

Example 5

[0067] <Preparation of Graft Polymer Powder>

[0068] A graft polymer powder was prepared in the same manner as in Example 1.

[0069] <Preparation of Thermoplastic Resin Composition>

[0070] A thermoplastic resin composition was prepared by uniformly mixing 45 parts by weight of the graft polymer powder and 55 parts by weight of the MSAN polymer of Preparing Example 1.

Comparative Examples 1 and 2

[0071] A graft polymer powder and a thermoplastic resin composition were prepared in the same manner as in Example 1 except that a reactive UV stabilizer (RUVA93 commercially available from Otsuka Chemical Co., Ltd.) was added to a reactor in an amount as shown below in Tables.

Comparative Example 3

[0072] <Preparation of Graft Polymer Powder>

[0073] Polymerization was performed while continuously adding 20 parts by weight(based on solid content) of a butadiene rubber polymer latex (PBL; gel content: 70%, average particle diameter: 300 nm), 17.5 parts by weight of butyl acrylate (BA), 12.5 parts by weight of styrene (S), 100 parts by weight of ion-exchanged water, 0.06 parts by weight of potassium persulfate, 0.5 parts by weight of sodium dioctyl sulfosuccinate, 0.28 parts by weight of ethylene glycol dimethacrylate, 0.1 parts by weight of allyl methacrylate, and 0.1 parts by weight of NaHCO.sub.3 to a reactor at a constant rate and 70° C. for three hours. Subsequently, after raising the temperature of the reactor to 80° C., polymerization was performed for one hour, and thereby a composite rubber polymer latex was obtained.

[0074] Polymerization was performed while continuously adding 34.56 parts by weight of methyl methacrylate (MMA), styrene (S) at 13.44 parts by weight, acrylonitrile (AN) at 2 parts by weight, 0.1 parts by weight of cumene hydroperoxide, 0.01 parts by weight of sodium ethylenediaminetetraacetate, 0.04 parts by weight of sodium formaldehyde sulfoxylate, 0.001 parts by weight of ferrous sulfate, 0.5 parts by weight of sodium oleate, and 0.5 parts by weight of t-dodecyl mercaptan to the composite rubber polymer latex at a constant rate and 75° C. for five hours. Subsequently, after raising the temperature of the reactor to 80° C., aging was performed for one hour and then polymerization was terminated, and thereby a graft polymer latex was obtained.

[0075] The graft polymer latex was coagulated using an aqueous calcium chloride solution and then aged, washed, dehydrated, and dried, and thereby a graft polymer powder was obtained.

[0076] <Preparation of Thermoplastic Resin Composition>

[0077] A thermoplastic resin composition was prepared by uniformly mixing 40 parts by weight of the graft polymer powder and 60 parts by weight of the MSAN polymer of Preparing Example 1.

Comparative Example 4

[0078] <Preparation of Graft Polymer Powder>

[0079] Polymerization was performed while continuously adding 50 parts by weight(based on solid content) of a butadiene rubber polymer latex (PBL; gel content: 70%, average particle diameter: 300 nm), 35.5 parts by weight of methyl methacrylic acid, 12.5 parts by weight of styrene, 2 parts by weight of acrylonitrile, 0.1 parts by weight of cumene hydroperoxide, 0.5 parts by weight of sodium oleate, 0.1 parts by weight of sodium ethylenediaminetetraacetate, 0.04 parts by weight of sodium formaldehyde sulfoxylate, and 0.001 parts by weight of ferrous sulfate to a reactor at a constant rate and 75° C. for five hours. Subsequently, after raising the temperature of the reactor to 80° C., aging was performed for one hour and then polymerization was terminated, and thereby a graft polymer latex was obtained.

[0080] The graft polymer latex was coagulated using an aqueous calcium chloride solution and then aged, washed, dehydrated, and dried, and thereby a graft polymer powder was obtained.

[0081] <Preparation of Thermoplastic Resin Composition>

[0082] A thermoplastic resin composition was prepared by uniformly mixing 40 parts by weight of the graft polymer powder and 60 parts by weight of the MSAN polymer of Preparing Example 1.

Comparative Example 5

[0083] <Preparation of Diene-Based Rubber Polymer>

[0084] 90 parts by weight of ion-exchanged water, 75 parts by weight of 1,3-butadiene (BD), 3.5 parts by weight of a reactive UV stabilizer (RUVA93 commercially available from Otsuka Chemical Co., Ltd.), 1.2 parts by weight of potassium rosinate, 0.8 parts by weight of potassium oleate, 1.0 part by weight of K.sub.2CO.sub.3, 0.4 parts by weight of t-dodecyl mercaptan, and 0.5 parts by weight of potassium persulfate were batch-added to a nitrogen-substituted polymerization reactor. After raising the temperature of the reactor to 70° C., polymerization was initiated.

[0085] Subsequently, when a polymerization conversion rate of about 35% was reached, 25 parts by weight of 1,3-butadiene (BD) and 0.15 parts by weight of potassium persulfate were batch-added to the reactor, and thus polymerization was continued.

[0086] Polymerization was performed while raising the temperature of the reactor to 80° C. when a polymerization conversion rate of about 60% was reached, and the polymerization was terminated when a polymerization conversion rate of 90% was reached, and thereby a butadiene rubber polymer latex (gel content: 70%, average particle diameter: 300 nm) was obtained.

[0087] <Preparation of Graft Polymer Powder>

[0088] Polymerization was performed while continuously adding 20 parts by weight(based on solid content) of the butadiene rubber polymer latex, 24 parts by weight of butyl acrylate (BA), 16 parts by weight of styrene (S), 100 parts by weight of ion-exchanged water, 0.1 parts by weight of cumene hydroperoxide, 0.01 parts by weight of sodium ethylenediaminetetraacetate, 0.04 parts by weight of sodium formaldehyde sulfoxylate, 0.0001 parts by weight of ferrous sulfate, 0.7 parts by weight of sodium dioctyl sulfosuccinate at, 0.4 parts by weight of ethylene glycol dimethacrylate, 0.1 parts by weight of allyl methacrylate, and 0.1 parts by weight of NaHCO.sub.3 to a reactor at a constant rate and 70° C. for three hours. Subsequently, after raising the temperature of the reactor to 80° C., polymerization was performed for one hour, and thereby a composite rubber polymer latex was obtained.

[0089] Polymerization was performed while continuously adding 28 parts by weight of methyl methacrylate (MMA), 10 parts by weight of styrene (S), 2 parts by weight of acrylonitrile (AN), 0.1 parts by weight of cumene hydroperoxide, 0.01 parts by weight of sodium ethylenediaminetetraacetate, 0.04 parts by weight of sodium formaldehyde sulfoxylate, 0.001 parts by weight of ferrous sulfate, 0.5 parts by weight of sodium oleate, and 0.4 parts by weight of t-dodecyl mercaptan to the composite rubber polymer latex at a constant rate and 75° C. for five hours. Subsequently, after raising the temperature of the reactor to 80° C., aging was performed for one hour and then polymerization was terminated, and thereby a graft polymer latex was obtained.

[0090] The graft polymer latex was coagulated using an aqueous calcium chloride solution and then aged, washed, dehydrated, and dried, and thereby a graft polymer powder was obtained.

[0091] <Preparation of Thermoplastic Resin Composition>

[0092] Athermoplastic resin composition was prepared by uniformly mixing 35 parts by weight of the graft polymer powder and 65 parts by weight of the MSAN polymer of Preparing Example 1.

Experimental Example 1

[0093] A property of the composite rubber polymers of Examples and Comparative Examples was evaluated by the method described below, and the results are shown below in Tables.

[0094] {circle around (1)} Average particle diameter (nm): Measured by a dynamic light scattering method using a Particle Sizing Systems Nicomp 380 instrument.

Experimental Example 2

[0095] A property of the graft polymer powders of Examples and Comparative Examples was evaluated by the method described below, and the results are shown in Tables 1 and 2.

[0096] {circle around (2)} Refractive index: Measured with an Abbe refractometer after irradiating a graft polymer powder with 589.3 nm visible light.

Experimental Example 3

[0097] After uniformly mixing 100 parts by weight of the thermoplastic resin compositions of Examples and Comparative Examples, 0.2 parts by weight of ethylene bis(stearate), 0.2 parts by weight of IR1076 and 0.1 parts by weight of Tinuvin 770 (commercially available from BASF SE), the mixtures were extruded and injection-molded to prepare specimens. Properties of the specimens were evaluated by the methods described below, and the results are shown below in Tables 1 and 2.

[0098] {circle around (3)} Haze value (%): Measured in accordance with ASTM 1003.

[0099] {circle around (4)} Notched Izod impact strength (kgf cm/cm, ¼ inch): Measured at 25° C. in accordance with ASTM D256.

[0100] {circle around (5)} Weather resistance: The weather resistance was evaluated by calculating, using the below equation, the color difference of a specimen before and after 500 hours of storage using ATLAS UV2000.

[0101] Meanwhile, weather resistance evaluation conditions were as follows:

[0102] Light source: Fluorescent UV lamps (40 W, UVA 340 lamp)

[0103] Irradiance: 0.55 W/m.sup.2 (340 nm)

[0104] Black panel temperature: 60° C.

ΔE=√{square root over ((L′−L.sub.0).sup.2+(a′−a.sub.0).sup.2+(b′−b.sub.0).sup.2)}

[0105] In the above equation, L′, a′, and b′ are the L, a, and b values measured in the CIE LAB color coordinate system after storing the specimen for 500 hours, and L.sub.0, a.sub.0, and b.sub.0 are the L, a, and b values measured in the CIE LAB color coordinate system before storage.

TABLE-US-00001 TABLE 1 Comparative Comparative Example Examples Example Classification 1 1 2 3 4 2 Composite rubber PBL 20 20 20 20 20 20 polymer latex BA 24 24 24 24 24 24 (parts by weight) S 16 16 16 16 16 16 Reactive UV 0.05 0.3 0.7 1.5 2 3 stabilizer Average particle 410 410 410 410 410 410 diameter (nm) Graft polymer powder MMA 28 28 28 28 28 28 (parts by weight) S 10 10 10 10 10 10 AN 2 2 2 2 2 2 Refractive index 1.516 1.516 1.516 1.516 1.516 1.516 Thermoplastic resin Graft polymer 35 35 35 35 35 35 composition powder (parts by weight) MSAN polymer of 65 65 65 65 65 65 Preparing Example 1 (parts by weight) Haze value 1.8 1.8 1.9 2.1 2.2 2.5 Impact strength 9 8.8 8.9 8.7 8.7 8.6 Weather resistance 4.2 1.5 0.9 0.8 0.6 0.6

TABLE-US-00002 TABLE 2 Comparative Comparative Comparative Classification Example 5 Example 3 Example 4 Example 5 Preparation of diene- BD — — — 100 based rubber polymer Reactive UV — — — 3.5 latex stabilizer (parts by weight) Average particle — — — 300 diameter (nm) Composite rubber PBL 20 20 50 20 polymer latex BA 24 17.5 0 24 (parts by weight) S 16 12.5 0 16 Reactive UV 0.7 0 0 0 stabilizer Average particle 410 390 300 410 diameter (nm) Graft polymer powder MMA 28 34.56 35.5 28 (parts by weight) S 10 13.44 12.5 10 AN 12 2 2 12 Refractive index 1.516 1.518 1.516 1.516 Thermoplastic resin Graft polymer 45 40 40 35 composition powder (parts by weight) MSAN polymer 55 60 60 65 (parts by weight) Haze value 2.1 2.1 1.9 2.5 Impact strength 12.3 8.3 18.1 8.5 Weather 1 3.9 7.2 2.1 resistance

[0106] Referring to Tables 1 and 2, in the case of Examples 1 to 5 in which an appropriate amount of a reactive UV stabilizer was used, it can be seen that all of transparency, impact strength, and weather resistance were excellent. On the other hand, in the case of Comparative Example 1 in which a small amount of a reactive UV stabilizer was used, weather resistance was significantly lowered. In the case of Comparative Example 2 in which an excessive amount of a reactive UV stabilizer was used, since transparency was lowered, the graft polymer is not appropriate as a transparent material. In the case of Comparative Example 3 in which a reactive UV stabilizer was not used, it can be seen that weather resistance was significantly lowered. In the case of Comparative Example 4 in which a reactive UV stabilizer was not used and a diene-based rubber polymer rather than a composite rubber polymer was used for preparing a graft polymer, it can be seen that weather resistance was significantly lowered. In the case of Comparative Example 5 in which a reactive UV stabilizer was used for preparing a diene-based rubber polymer latex, it can be seen that transparency, impact resistance, and weather resistance were lowered. In the case of Comparative Example 5, as compared to Example 2, in which the amount of a reactive UV stabilizer contained in a graft copolymer was the same and only the timing of addition of the reactive UV stabilizer was different, it can be seen that transparency, impact resistance, and weather resistance were lowered.