KR102537159B1 - Method for preparing graft copolymer - Google Patents

Abstract

In the present invention, in the presence of an azo-based initiator having a solubility in water of 10 g/100 g or more at 20 ° C and a half-life decomposition temperature of 80 ° C or less in water, an aromatic vinyl monomer and a vinyl cyanide-based monomer are added to a diene rubber polymer. It relates to a method for producing a graft copolymer comprising the step of graft emulsion polymerization and starting the graft emulsion polymerization at 45 to 55 ° C. According to the present invention, polymerization can be performed at a low temperature, while polymerization stability A method for producing this excellent graft copolymer can be provided.

Description

Method for preparing graft copolymer {METHOD FOR PREPARING GRAFT COPOLYMER}

[Mutual Citation with Related Applications]

The present invention claims the benefit of priority based on Korean Patent Application No. 10-2019-0089775 filed on July 24, 2019, and includes all contents disclosed in the literature of the Korean patent application as part of this specification.

[Technical field]

The present invention relates to a method for preparing a graft copolymer, and relates to a method for preparing a graft copolymer using an azo-based initiator that is water-soluble and has a low 10-hour half-life in water and a low decomposition temperature.

In the case of a diene-based graft copolymer prepared by emulsion polymerization, a redox initiation system is most widely used as a polymerization initiation system. The redox initiation system has the advantage of being able to control the polymerization in a relatively short time because the polymerization initiation temperature is low and the polymerization rate is fast.

However, the redox initiation system has problems in that the thermal stability of the graft copolymer is lowered by the metal oxide and the reducing agent, so that a lot of antioxidants must be added during processing and the whiteness is lowered. In order to solve this problem, attempts have been made to introduce a thermal decomposition initiator such as benzoyl persulfate or potassium persulfate into polymerization, but the polymerization initiation temperature is high, the polymerization rate is slow, and the processability and impact resistance of the graft copolymer are reduced. this has occurred

Accordingly, research on a method for preparing a graft copolymer capable of producing a graft copolymer having a low polymerization initiation temperature, a high polymerization rate, and excellent physical properties is being continued.

KR2011-0079634A

An object of the present invention is to provide a method for preparing a graft copolymer capable of achieving a polymerization initiation temperature and polymerization rate equivalent to that of a redox initiation system and having excellent thermal stability, impact resistance and color characteristics. is to provide

In order to solve the above problems, the present invention is a diene-based rubbery polymer in the presence of an azo-based initiator having a solubility in water of 10 g / 100 g or more at 20 ° C. and a half-life decomposition temperature of 80 ° C. or less in water, aromatic vinyl It provides a method for producing a graft copolymer comprising the step of graft emulsion polymerization of a monomer and a vinyl cyanide monomer, and initiating the graft emulsion polymerization at 45 to 55 °C.

In addition, it is molded with a thermoplastic resin composition containing the graft copolymer prepared according to the above-described manufacturing method, and has a flow index of 18 to 22 g / 10 minutes measured under 220 ° C. and 10 kg conditions according to ASTM D1238, ASTM Provided is a thermoplastic resin molded article having an impact strength of 20 kg·cm/cm or more as measured according to D256 and a whiteness of 61 or more as measured according to ASTM D1925.

According to the method for preparing the graft copolymer of the present invention, the polymerization efficiency can be remarkably improved because the polymerization initiation temperature is low, the polymerization rate is high, and the polymerization stability is excellent. In addition, excellent thermal stability can be realized without using an excessive amount of antioxidant during processing of the graft copolymer. In addition, a graft copolymer excellent in processability, impact resistance and color characteristics can be prepared.

Hereinafter, embodiments of the present invention will be described in detail so that those skilled in the art can easily implement the present invention. However, the present invention may be embodied in many different forms and is not limited to the embodiments described herein.

In the present invention, solubility in water means the concentration of solute in a saturated solution, and means the number of grams of initiator dissolved in 100 g of water as a solvent at 20 °C.

In the present invention, '10 hour half-life decomposition temperature in water' means the temperature required to reduce the content of the azo-based initiator to 50% based on 10 hours in water.

The decomposition temperature of the 10-hour half-life in water of the azo-based initiator can be measured by monitoring the thermal activity of a dilute solution of the azo-based initiator diluted in water using a differential scanning calorimeter (DSC) device.

In addition, the half-life of the azo-based initiator can be calculated by the following Arrhenius equation.

k _d = A e ^-Ea/RT

t _1/2 = ln2/k _d

k _d = rate constant for the initiator dissociation in s ^-1

A = Arrhenius frequency factor in s ^-1

E _a = Activation energy for the initiator dissociation in J/mole

R = gas constant (8.3142 J/mole K)

T = temperature in K

t _1/2 = half-life in s

Meanwhile, the residual concentration of the initiator can be calculated by the following formula.

[I] = [I ₀ ] e ^{-kd t}

[I ₀ ] = original initiator concentration

[I] = concentration of initiator at time t (initiator concentration at time t)

t = time measured from the start of decomposition in s

In the present invention, the diene-based rubbery polymer is made of a conjugated diene-based monomer, and the conjugated diene-based monomer may be at least one selected from the group consisting of 1,3-butadiene, isoprene, chloroprene, and piperylene, among which one, 3-butadiene is preferred.

In the present invention, the diene-based rubbery polymer may have an average particle diameter of 50 to 500 nm or 70 to 400 nm, of which 70 to 400 nm is preferable. When the above range is satisfied, a graft copolymer having excellent impact strength and surface gloss can be prepared.

In the present invention, the average particle diameter of the diene-based rubbery polymer may mean the arithmetic average particle diameter in the particle size distribution measured by dynamic light scattering, specifically, the scattering intensity average particle diameter. The average particle diameter of the diene-based rubbery polymer can be measured using Nicomp 380 equipment (product name, manufacturer: PSS Nicomp).

In the present invention, the aromatic vinyl monomer may be at least one selected from the group consisting of styrene, α-methyl styrene, α-ethyl styrene, and p-methyl styrene, of which styrene is preferred. A unit derived from the aromatic vinyl-based monomer may be an aromatic vinyl-based monomer unit.

In the present invention, the vinyl cyanide-based monomer may be at least one selected from the group consisting of acrylonitrile, methacrylonitrile, phenylacrylonitrile, and α-chloroacrylonitrile, of which acrylonitrile is preferable. The unit derived from the vinyl cyanide-based monomer may be a vinyl cyanide-based monomer unit.

1. Manufacturing method of graft copolymer

A method for preparing a graft copolymer according to an embodiment of the present invention is a solubility in water at 20 ° C. of 10 g / 100 g or more, a 10-hour half-life decomposition temperature in water of 80 ° C. or less In the presence of an azo-based initiator, A step of graft emulsion polymerization of an aromatic vinyl monomer and a vinyl cyanide monomer to a diene-based rubbery polymer, wherein the graft emulsion polymerization is initiated at 45 to 55 °C.

The use of a redox initiation system has advantages of a low polymerization initiation temperature and a fast polymerization rate, but thermal stability is deteriorated due to metal oxides and reducing agents used as oxidation-reduction catalysts. Therefore, in order to improve thermal stability, an excessive amount of antioxidants should be used during processing of the graft copolymer, but there is a disadvantage in that the whiteness is remarkably lowered due to the excessive amount of antioxidants. In addition, when a thermal decomposition initiator is used, polymerization efficiency is lowered due to a high polymerization initiation temperature and a slow polymerization rate, and disadvantages in that thermal stability, processability, and impact resistance of the graft copolymer are deteriorated. In order to solve these disadvantages, the present inventors studied an initiator suitable for polymerization of graft copolymers, and as a result, a solubility in water at 20 ° C. is 10 g / 100 g or more, a half-life in water of 10 hours, and a decomposition temperature of 80 ° C. It was found that using the azo-based initiator below, a graft copolymer having excellent thermal stability, processability, impact resistance and color characteristics while realizing polymerization initiation temperature and polymerization rate at the same level as the redox initiation system can be prepared. , thereby completing the present invention.

The azo-based initiator has a water solubility of 10 g/100 g or more at 20° C., preferably 10 g/100 g to 40 g/100 g, more preferably 10 g/100 g to 20 g/100 g. can be g. If the above conditions are satisfied, it is not only suitable for emulsion polymerization where the solvent is water, but also increases the amount of azo-based initiator that can participate in emulsion polymerization than before, so that the polymerization rate can be realized at a speed equivalent to that of the redox initiation system. The polymerization conversion rate may also be increased. In addition, the graft rate and weight average molecular weight of the graft copolymer may be increased to improve impact resistance. If the conditions are less than the above, since the amount of the azo-based initiator that can participate in the polymerization is small, the polymerization rate is slowed down, the polymerization conversion rate is also reduced, and the polymerization efficiency may be lowered.

The azo-based initiator may have a 10-hour half-life in water and a decomposition temperature of 80 °C or less, preferably 35 °C to 65 °C, more preferably 50 °C to 65 °C. If the above conditions are satisfied, it is suitable for emulsion polymerization in which the solvent is water, and the polymerization initiation temperature can be implemented as low as that of the redox initiation system, and polymerization stability is improved, so that polymerization efficiency can be remarkably improved. If the above temperature conditions are exceeded, the polymerization initiation temperature may increase and the polymerization stability may decrease, resulting in a decrease in polymerization efficiency.

The graft emulsion polymerization may be initiated at 45 to 55 °C, preferably at 47 to 52 °C. If the above conditions are satisfied, the energy required to raise the temperature of the reactor can be saved, and thus the polymerization efficiency can be improved. In addition, since the amount of agglomerates is reduced and the final polymerization conversion rate is increased during the preparation of the graft copolymer, polymerization stability and polymerization efficiency can be improved. In addition, the thermal stability, impact resistance and color properties of the graft copolymer can be improved. If the graft emulsion polymerization is initiated at a temperature lower than the above-mentioned temperature, the thermal stability, processability and color characteristics of the graft copolymer may be deteriorated. If the graft emulsion polymerization is initiated at a temperature exceeding the above-mentioned temperature, the amount of coagulation may increase and polymerization stability and polymerization efficiency may be deteriorated. In addition, thermal stability, impact resistance, and color characteristics of the graft copolymer may be significantly deteriorated.

The azo-based initiator may be at least one selected from the group consisting of compounds represented by Formulas 1 to 3 below:

<Formula 1>

<Formula 2>

<Formula 3>

The azo-based initiator may be present in an amount of 0.01 to 0.5 parts by weight, 0.03 to 0.4 parts by weight, or 0.08 to 0.25 parts by weight based on 100 parts by weight of the sum of the diene-based rubbery polymer, the aromatic vinyl-based monomer, and the vinyl cyanide-based monomer, , Of which it is preferably present in an amount of 0.08 to 0.25 parts by weight. When the above conditions are satisfied, the polymerization rate is increased to increase the polymerization conversion rate, and the polymerization stability is improved, so that the formation of agglomerates in the graft copolymer can be minimized. In addition, the thermal stability, processability, impact strength and whiteness of the graft copolymer can be improved.

Meanwhile, the diene-based rubbery polymer may participate in the graft emulsion polymerization in an amount of 45 to 65 parts by weight or 50 to 60 parts by weight based on 100 parts by weight of the sum of the diene-based rubbery polymer, the aromatic vinyl monomer, and the vinyl cyanide monomer. Among them, it is preferable to participate in graft emulsion polymerization in an amount of 50 to 60 parts by weight. If the above conditions are satisfied, the graft copolymer can realize excellent impact strength and surface gloss.

The aromatic vinyl monomer may participate in the graft emulsion polymerization in an amount of 20 to 40 parts by weight or 25 to 35 parts by weight based on 100 parts by weight of the total of the diene-based rubbery polymer, the aromatic vinyl-based monomer, and the vinyl cyanide-based monomer, , It is preferable to participate in the graft emulsion polymerization in an amount of 25 to 35 parts by weight. If the above conditions are satisfied, the graft copolymer can realize excellent processability.

The vinyl cyanide-based monomer may participate in graft emulsion polymerization in an amount of 7 to 20 parts by weight or 10 to 15 parts by weight based on 100 parts by weight of the total of the diene-based rubbery polymer, the aromatic vinyl-based monomer, and the vinyl cyanide-based monomer, , It is preferable to participate in the graft emulsion polymerization in an amount of 10 to 15 parts by weight. If the above conditions are satisfied, the graft copolymer can realize excellent chemical resistance.

Meanwhile, the method for preparing the graft copolymer includes the steps of firstly introducing the diene-based rubbery polymer, the aromatic vinyl-based monomer, the vinyl cyanide-based monomer, and the azo-based initiator into a reactor, and then initiating emulsion polymerization; and performing emulsion polymerization while continuously secondarily introducing an aromatic vinyl monomer, a vinyl cyanide monomer, and an azo-based initiator into the reactor.

In the step of initiating the emulsion polymerization and the step of performing the emulsion polymerization, an azo-based initiator is introduced into the reactor at a weight ratio of 1:1 to 1:3, 1:1 to 1:2.5, or 1:1.5 to 1:2.5. It is possible, and it is preferable to introduce it into the reactor so that the weight ratio of 1: 1.5 to 1: 2.5. When the above conditions are satisfied, the polymerization conversion rate can be increased, and the heat removal can be easily carried out, so that the polymerization can be stably carried out.

In the step of initiating the emulsion polymerization and the step of performing the emulsion polymerization, aromatic vinyl monomers may be introduced into the reactor at a weight ratio of 1:3 to 1:12, or 1:5 to 1:10, among which It is preferable to introduce it into the reactor so that it has a weight ratio of 1:5 to 1:10. If the above conditions are satisfied, the graft copolymer can secure an excellent graft rate.

In the step of initiating the emulsion polymerization and the step of performing the emulsion polymerization, the vinyl cyanide-based monomer may be introduced into the reactor at a weight ratio of 1:3 to 1:12 or 1:5 to 1:10, of which It is preferable to introduce it into the reactor so that it has a weight ratio of 1:5 to 1:10. If the above conditions are satisfied, the graft copolymer can secure an excellent graft rate.

In the step of initiating the emulsion polymerization and the step of performing the emulsion polymerization, at least one selected from the group consisting of an emulsifier, a molecular weight modifier, and water may be additionally added.

The emulsifier may be at least one selected from the group consisting of an alkali metal salt of rosin acid, an alkali metal salt of a fatty acid, and an alkali metal dimer of a fatty acid, among which a dimer alkali metal salt of a fatty acid is preferable. The alkali metal salt of rosin acid may be at least one selected from the group consisting of potassium salt of rosin acid and sodium salt of rosin acid, and among these, potassium salt of rosin acid is preferred. The fatty acid alkali metal salt may be a C ₈ to C ₂₀ fatty acid alkali metal salt, an alkali metal salt of capric acid, an alkali metal salt of lauric acid, an alkali metal salt of palmitic acid, an alkali metal salt of stearic acid, an alkali metal salt of oleic acid, and linol At least one selected from the group consisting of alkali metal salts of lanic acid is more preferred. The fatty acid dimer alkali metal salt may be a C ₈ to C ₂₀ fatty acid dimer alkali metal salt, preferably a C ₈ to C ₂₀ fatty acid dimer potassium salt, and more preferably an oleic acid dimer potassium salt.

The emulsifier may be added in an amount of 0.1 to 1 part by weight or 0.2 to 0.7 part by weight, based on 100 parts by weight of the sum of the diene-based rubbery polymer, the aromatic vinyl monomer, and the vinyl cyanide-based monomer, of which 0.2 to 0.7 part by weight is added. it is desirable to be When included within the above range, polymerization stability may be excellent while maintaining a proper polymerization rate. In addition, discoloration and gas generation due to the emulsifier can be minimized.

In the step of initiating the emulsion polymerization and the step of performing the emulsion polymerization, the emulsifier may be added in a weight ratio of 1:1 to 1:7 or 1:2 to 1:5, of which 1:2 to 1:5 It is preferable to add so that the weight ratio of When included within the above range, polymerization stability may be excellent while maintaining a proper polymerization rate.

The molecular weight regulator may be at least one selected from the group consisting of t-dodecyl mercaptan, n-dodecyl mercaptan, n-octyl mercaptan and α-methyl styrene dimer, among which t-dodecyl mercaptan and At least one selected from the group consisting of α-methyl styrene dimer is preferred.

The molecular weight modifier may be added in an amount of 0.1 to 0.5 parts by weight or 0.1 to 0.3 parts by weight, of which 0.1 to 0.3 parts by weight, based on 100 parts by weight of the total of the diene rubber polymer, the aromatic vinyl monomer, and the vinyl cyanide monomer. It is preferable to put in When included within the above-described range, it may serve not only as a molecular weight modifier, but also as a polymerization accelerator while appropriately maintaining a polymerization rate.

In the step of initiating the emulsion polymerization and the step of performing the emulsion polymerization, the molecular weight modifier may be added at a weight ratio of 1:1 to 1:7 or 1:2 to 1:5, of which 1:2 to 1: It is preferable to add so as to have a weight ratio of 5. When included in the above range, while properly maintaining the polymerization rate, it can also perform the role of polymerization accelerator.

2. Thermoplastic resin molding

A thermoplastic molded article according to another embodiment of the present invention is molded with a thermoplastic resin composition containing a copolymer prepared by the method for preparing a graft copolymer according to an embodiment of the present invention, and in accordance with ASTM D1238, 220 ° C. and The flow index measured under the condition of 10 kg is 18 to 22 g/10 min, the impact strength measured according to ASTM D256 is 20 kg cm/cm or more, and the whiteness measured according to ASTM D1925 is 61 or more.

The thermoplastic resin molded article preferably has a flow index of 19 to 21 g/10 min, an impact strength of 20 to 23 kg cm/cm, and a whiteness of 61 to 64. If the above conditions are satisfied, a thermoplastic resin molded article having excellent processability, impact resistance and color characteristics can be manufactured.

The thermoplastic resin composition may include a non-grafted copolymer including an aromatic vinyl-based monomer unit and a cyanide-based vinyl monomer unit.

The thermoplastic resin composition may include the graft copolymer and the non-graft copolymer in a weight ratio of 10:90 to 40:60, preferably 20:80 to 30:70. When the above range is satisfied, a thermoplastic resin composition having excellent processability and impact resistance can be manufactured.

The non-grafted copolymer may include a vinyl monomer unit and a vinyl cyanide monomer unit in a weight ratio of 60:40 to 80:20, preferably 65:35 to 75:25. If the above conditions are satisfied, a thermoplastic resin composition having excellent processability and chemical resistance can be prepared.

The non-grafted copolymer is preferably a styrene/acrylonitrile non-grafted copolymer.

Hereinafter, embodiments of the present invention will be described in detail so that those skilled in the art can easily implement the present invention. However, the present invention may be embodied in many different forms and is not limited to the embodiments described herein.

Information on the initiator used in the following Examples and Comparative Examples is as follows.

(A) Initiator

(A-1) VA-044 from FUJIFILM Wako Pure Chemical Corporation was used.

structure:

Solubility in water at 20 °C: 35.2 g/100 g

10 hour half-life in water. Decomposition temperature: 44 °C.

(A-2) VA-050 from FUJIFILM Wako Pure Chemical Corporation was used.

structure:

Solubility in water at 20 °C: 23.2 g/100 g

10 hour half-life in water. Decomposition temperature: 56 °C.

(A-3) VA-057 from FUJIFILM Wako Pure Chemical Corporation was used.

structure:

Solubility in water at 20 °C: 14 g/100 g

10 hour half-life in water. Decomposition temperature: 57 °C.

(A-4) VA-061 from FUJIFILM Wako Pure Chemical Corporation was used.

structure:

Solubility in water at 20 °C: 0.5 g/100 g

10 hour half-life in methanol. Decomposition temperature: 61 °C.

(A-5) VA-501 from FUJIFILM Wako Pure Chemical Corporation was used.

structure:

Solubility in water at 20 °C: 0.1 g/100 g

10 hour half-life in water. Decomposition temperature: 69 °C.

(A-6) VA-086 from FUJIFILM Wako Pure Chemical Corporation was used.

structure:

Solubility in water at 20 °C: 2.4 g/100 g

10 hour half-life in water. Decomposition temperature: 86 °C.

(A-7) V-65 from FUJIFILM Wako Pure Chemical Corporation was used.

structure:

Solubility in water at 20 °C: < 0.1 g/100 g

10 hour half-life in toluene. Decomposition temperature: 51 °C.

(A-8) AIBN from FUJIFILM Wako Pure Chemical Corporation was used.

structure:

Solubility in water at 20 °C: < 0.1 g/100 g

10 hour half-life in toluene. Decomposition temperature: 65 °C.

(A-9) Benzoyl peroxide was used.

(A-10) Potassium persulfate was used.

(A-11) Cumene hydroperoxide was used.

Examples 1 to 7 and Comparative Examples 1 to 9

<Preparation of Graft Copolymer>

In a reactor filled with nitrogen, 120 parts by weight of ion-exchanged water, 55 parts by weight of butadiene rubbery polymer latex (based on solid content, average particle diameter: 300 nm), 3.5 parts by weight of styrene, 1.5 parts by weight of acrylonitrile, 0.1 part by weight of potassium rosinate salt, 0.1 part by weight of t-dodecyl mercaptan and the type and amount of initiators listed in Tables 1 to 4 below were first added, and then the temperature of the reactor was raised to the temperature shown in Tables 1 to 4 below to initiate polymerization.

On the other hand, 28 parts by weight of styrene, 12 parts by weight of acrylonitrile, 0.4 parts by weight of potassium rosin acid salt, 0.3 parts by weight of t-dodecyl mercaptan, and the types and contents shown in Tables 1 to 4 below were uniformly mixed with the initiator. A polymerization solution was prepared.

While raising the temperature of the reactor at a constant rate to 80 ° C. at the same time as the polymerization was started, the polymerization solution was continuously secondarily introduced into the reactor for 3 hours to perform polymerization, and the polymerization was terminated to obtain a graft copolymer latex. 0.4 parts by weight of Wingstay L from Daeyoung Industry Co. was added to the graft copolymer latex. Then, the graft copolymer latex was agglomerated with 2 parts by weight of sulfuric acid, aged, dehydrated, and dried to prepare a graft copolymer powder having a moisture content of less than 1% by weight.

<Preparation of thermoplastic resin composition>

A thermoplastic resin composition was prepared by uniformly mixing 25 parts by weight of the graft copolymer powder and 75 parts by weight of LG Chem's 92HR (styrene/acrylonitrile copolymer).

Comparative Example 10

<Preparation of Graft Copolymer>

In a reactor filled with nitrogen, 120 parts by weight of ion-exchanged water, 55 parts by weight of butadiene rubbery polymer latex (based on solid content, average particle diameter: 300 nm), 3.5 parts by weight of styrene, 1.5 parts by weight of acrylonitrile, 0.1 part by weight of potassium rosinate salt, 0.1 part by weight of t-dodecyl mercaptan, 0.15 part by weight of dextrose, 0.1 part by weight of sodium pyrophosphate, 0.001 part by weight of ferrous sulfate, and the type and amount shown in Table 4 below were first added to the initiator, and then the above Polymerization was initiated by raising the temperature of the reactor to the temperature shown in Table 4 below.

On the other hand, 28 parts by weight of styrene, 12 parts by weight of acrylonitrile, 0.4 parts by weight of potassium rosin acid salt, 0.3 parts by weight of t-dodecyl mercaptan, and the types and contents shown in Table 4 are uniformly mixed with the initiator to obtain a polymerization solution. manufactured.

While raising the temperature of the reactor at a constant rate to 80 ° C., the polymerization solution was continuously secondarily injected into the reactor for 3 hours, and the polymerization was terminated to obtain graft copolymer latex. 0.3 parts by weight of an antioxidant (Daeyoung Industry Co., Ltd. Wingstay L) was added to the graft copolymer latex. Then, the graft copolymer latex was agglomerated with 2 parts by weight of sulfuric acid, aged, dehydrated, and dried to prepare a graft copolymer powder having a moisture content of less than 1% by weight.

<Preparation of thermoplastic resin composition>

A thermoplastic resin composition was prepared by uniformly mixing 25 parts by weight of the graft copolymer powder and 75 parts by weight of LG Chem's 92HR (styrene/acrylonitrile copolymer).

Comparative Example 11

A graft copolymer powder and a thermoplastic resin composition were prepared in the same manner as in Comparative Example 10, except that 0.8 parts by weight of the antioxidant (Daeyoung Industry's Wingstay L) was added instead of 0.3 parts by weight.

Experimental Example 1

The physical properties of the graft copolymer latex and powder of Examples and Comparative Examples were measured by the methods described below, and the results are shown in Tables 1 to 4 below.

① Polymerization conversion rate (%): 5 g of the graft copolymer latex was dried in a hot air dryer set at 150 ° C for 15 minutes, and only the solid content was taken to obtain the concentration of the total solid content (measured value TSC) for the initial latex. Polymerization conversion was calculated.

Polymerization conversion rate (%) = [(total parts by weight of monomers, auxiliary materials and ion-exchanged water added during polymerization) × (measured value TSC)] - (total parts by weight of unreacted monomers and auxiliary materials)

② Clot amount (% by weight): After filtering the graft copolymer latex using a 100 mesh net, it was put into a convention oven and left at 80 ° C. for 720 minutes. Thereafter, the weight of the coagulum caught on the 100 mesh net was measured, and the coagulation amount of the graft copolymer latex was calculated according to the following formula.

Amount of coagulum (% by weight) = {(weight of coagulum caught on 100 mesh net)/(theoretical total weight of butadiene rubbery polymer, styrene, acrylonitrile, and additives added during the preparation of the graft copolymer)} × 100

③ Oxidative Induction Time (minutes): DSC (Differential Scanning Calorimetry) in accordance with ASTM D3895 was used to measure the time for oxidation to occur under isothermal conditions of 190 ° C. while introducing 50 ml of oxygen per minute.

Experimental Example 2

The thermoplastic resin compositions of Examples and Comparative Examples were extruded into pellets. The physical properties of the pellets were measured as follows, and the results are shown in Tables 1 to 4 below.

④ Melt Flow Index (g/10 min): Measured under the condition of 220 ℃ and 10 kg in accordance with ASTM D1238.

Experimental Example 3

Specimens were prepared by extruding and injecting the thermoplastic resin compositions of Examples and Comparative Examples. The physical properties of the specimen were measured as follows, and the results are shown in Tables 1 to 4 below.

⑤ Izod impact strength (kg cm/cm, 1/4 In): measured according to ASTM D256.

⑥ White Index: Measured according to ASTM D1925.

division Example One 2 3 4 5 (A) Initiator
(parts by weight) (A-1) 1st input 0.05 - - - - 2nd input 0.1 - - - - (A-2) 1st input - 0.05 - - - 2nd input - 0.1 - - - (A-3) 1st input - - 0.025 0.05 0.1 2nd input - - 0.05 0.1 0.2 Polymerization initiation temperature (℃) 50 50 50 50 50 graft copolymer Polymerization conversion rate (%) 98.1 97.7 96.5 98.0 98.0 Clot amount (% by weight) 0.01 0.01 0.025 0.02 0.05 Oxidation induction time (min) 88 73 80 82 67 thermoplastic resin composition Flow rate (g/10 min) 19 19 18 20 21 Impact strength (kg cm/cm) 22.8 22.1 20.1 22.5 18.8 whiteness 63 64 63 63 61

division Example comparative example 6 7 One 2 (A) Initiator
(parts by weight) (A-1) 1st input 0 0 0 0 2nd input 0 0 0 0 (A-2) 1st input 0 0 0 0 2nd input 0 0 0 0 (A-3) 1st input 0.05 0.05 0.05 0.05 2nd input 0.1 0.1 0.1 0.1 Polymerization initiation temperature (℃) 45 55 44 56 graft copolymer Polymerization conversion rate (%) 97.7 98.1 96.3 98.0 Clot amount (% by weight) 0.014 0.015 0.012 0.09 Oxidation induction time (min) 79 79 51 62 thermoplastic resin composition Flow rate (g/10 min) 19 20 16 22 Impact strength (kg cm/cm) 22.8 22.4 22.1 17.7 whiteness 63 63 58 61

division comparative example 3 4 5 6 7 (A) Initiator
(parts by weight) (A-4) 1st input 0.05 - -
- - 2nd input 0.1 - -
- - (A-5) 1st input - 0.05 - - - 2nd input - 0.1 - - (A-6) 1st input - - 0.05 - - 2nd input - - 0.1 - - (A-7) 1st input - - - 0.05 - 2nd input - - - 0.1 - (A-8) 1st input - - - - 0.04 2nd input - - - - 0.08 Polymerization initiation temperature (℃) 50 50 50 50 70 graft copolymer Polymerization conversion rate (%) 83.2 85.3 96.7 88.2 95.5 Clot amount (% by weight) 1.7 1.3 0.02 2.3 1.9 Oxidation induction time (min) 51 48 76 52 61 thermoplastic resin composition Flow rate (g/10 min) 12 13 16 14 13 Impact strength (kg cm/cm) 16.8 18.1 19.8 18.8 18.5 whiteness 61 61 62 60 60

division comparative example 8 9 10 11 (A) Initiator (A-9) 1st input 0.05 - - - 2nd input 0.1 - - - (A-10) 1st input - 0.05 - - 2nd input - 0.1 - - (A-11) 1st input - - 0.05 0.05 2nd input - - 0.1 0.1 Polymerization initiation temperature (℃) 70 70 50 50 graft copolymer Polymerization conversion rate (%) 92.5 97.9 97.5 97.5 Clot amount (% by weight) 2.1 0.05 0.03 0.03 Oxidation induction time (min) 55 70 18 45 thermoplastic resin composition Flow rate (g/10 min) 12 7 21 20 Impact strength (kg cm/cm) 10.7 7.2 22.1 21.6 whiteness 61 53 58 56

Referring to the above table, the graft copolymers of Examples 1 to 7 using an azo-based initiator having a water solubility of 10 g / 100 g or more at 20 ° C. and a 10-hour half-life decomposition temperature in water of 80 ° C. or less Since the polymerization conversion rate was high and the amount of coagulum was small, polymerization stability and polymerization efficiency were excellent. In addition, the graft copolymers of Examples 1 to 7 had excellent polymerization stability due to a small amount of agglomerates, and excellent thermal stability due to a long oxidation induction time. In addition, since the thermoplastic resin compositions of Examples 1 to 7 had high flow index, impact strength and whiteness, they were excellent in processability, impact resistance and color characteristics.

On the other hand, comparing Examples 4, 6, 7, Comparative Example 1 and Comparative Example 2, the grafts of Examples 4, 6 and 7 prepared by initiating polymerization at 45 to 55 ° C. Since the copolymer had a long oxidation induction time, thermal stability was excellent. In addition, since the thermoplastic resin compositions of Examples 4, 6 and 7 had high flow index, impact strength and whiteness, they were excellent in processability, impact resistance and color characteristics. However, the graft copolymer of Comparative Example 1 prepared by initiating polymerization at 44° C. had a short oxidation induction time, and thus had poor thermal stability. Since the thermoplastic resin composition of Comparative Example 1 had low flow index and low whiteness, processability and color characteristics were not excellent. In addition, the graft copolymer of Comparative Example 2 prepared by initiating polymerization at 56° C. had a short oxidation induction time, and thus had poor thermal stability. Also, since the thermoplastic resin composition of Comparative Example 2 had low impact strength, impact resistance was not excellent.

The graft copolymer of Comparative Example 3 prepared using an azo-based initiator having a water solubility of 0.5 g/100 g at 20 °C had a low polymerization conversion rate and a large amount of agglomerates, so the polymerization efficiency was low. In addition, since the oxidation induction time was short, the thermal stability was not excellent. Since the thermoplastic resin composition of Comparative Example 3 had low flow index and low impact strength, processability and impact resistance were not excellent.

The graft copolymer of Comparative Example 4 prepared using an azo-based initiator having a water solubility of 0.1 g/100 g at 20 °C had a low polymerization conversion rate and a large amount of agglomerates, so the polymerization efficiency was low. In addition, since the oxidation induction time was short, the thermal stability was not excellent. Since the thermoplastic resin composition of Comparative Example 4 had low flow index and low impact strength, processability and impact resistance were not excellent.

The thermoplastic resin composition of Comparative Example 5 comprising a graft copolymer prepared using an azo-based initiator having a solubility in water at 20 ° C. of 2.4 g / 100 g and a half-life decomposition temperature of 86 ° C. in water for 10 hours had a flow index And since the impact strength was low, processability and impact resistance were not excellent.

The graft copolymer of Comparative Example 6 using an azo-based initiator having a water solubility of less than 0.1 g/100 g at 20 °C had a low polymerization conversion rate and a large amount of agglomerates, so the polymerization efficiency was low. In addition, since the oxidation induction time was short, the thermal stability was not excellent. Since the thermoplastic resin composition of Comparative Example 6 had low flow index and low impact strength, processability and impact resistance were not excellent.

The graft copolymer of Comparative Example 7 in which an azo-based initiator having a solubility in water of less than 0.1 g/100 g at 20 ° C. and graft emulsion polymerization was initiated at 70 ° C. has a large amount of agglomerates, so polymerization stability and polymerization efficiency this has been lowered In addition, since the graft copolymer of Comparative Example 7 had a short oxidation induction time, thermal stability was not excellent. Since the thermoplastic resin composition of Comparative Example 7 had low flow index and low impact strength, processability and impact resistance were not excellent.

The graft copolymer of Comparative Example 8 in which graft emulsion polymerization was initiated at 70° C. using benzoyl peroxide had a large amount of agglomerates, and thus polymerization stability and polymerization efficiency were reduced. In addition, since the oxidation induction time was short, the thermal stability was not excellent. Since the thermoplastic resin composition of Comparative Example 8 had low flow index and low impact strength, processability and impact resistance were not excellent.

The thermoplastic resin composition of Comparative Example 9 including the graft copolymer prepared by initiating graft emulsion polymerization at 70 ° C. using potassium persulfate has low flow index, impact strength and whiteness, so it has excellent processability, impact resistance and color. Characteristics were not good.

The graft copolymer of Comparative Example 10 prepared using cumene hydroperoxide had a short oxidation induction time and thus had poor thermal stability. Since the thermoplastic resin composition of Comparative Example 10 had low whiteness, color characteristics were also not excellent.

The graft copolymer of Comparative Example 11 was graft emulsion polymerization in the same manner as the graft copolymer of Comparative Example 10, but was prepared by adding an excessive amount of antioxidant in the post-treatment process. Compared to the graft copolymer, the oxidation induction time was longer, but the oxidation induction time was shorter than Examples 1 to 7. In addition, the thermoplastic resin composition of Comparative Example 11 had slightly reduced impact strength and whiteness compared to the thermoplastic resin composition of Comparative Example 10.

Claims (10)

In the presence of an azo-based initiator having a water solubility of 10 g/100 g or more at 20 °C and a half-life in water of 80 °C or less and a decomposition temperature of 80 °C or less, aromatic vinyl monomers and vinyl cyanide-based monomers are grafted onto diene-based rubbery polymers. Including the step of emulsion polymerization,
A method for producing a graft copolymer in which the graft emulsion polymerization is initiated at 45 to 55 ° C.
The method of claim 1,
The azo-based initiator has a solubility in water at 20 ° C. of 10 g / 100 g to 40 g / 100 g.
The method of claim 1,
The azo-based initiator has a 10-hour half-life in water and a decomposition temperature of 35 ° C to 65 ° C.
The method of claim 1,
The method for producing a graft copolymer wherein the azo-based initiator is at least one selected from the group consisting of compounds represented by Formulas 1 to 3 below:
<Formula 1>

<Formula 2>

<Formula 3>

The method of claim 1,
The azo-based initiator is present in an amount of 0.01 to 0.5 parts by weight based on 100 parts by weight of the total of the diene-based rubbery polymer, the aromatic vinyl-based monomer, and the vinyl cyanide-based monomer.
The method of claim 1,
The method for preparing the graft copolymer
firstly introducing the diene-based rubbery polymer, the aromatic vinyl-based monomer, the vinyl cyanide-based monomer, and the azo-based initiator into a reactor, and then starting emulsion polymerization; and
A method for producing a graft copolymer comprising the step of performing emulsion polymerization while continuously secondarily introducing an aromatic vinyl monomer, a vinyl cyanide monomer, and an azo initiator into the reactor.
The method of claim 6,
A method for producing a graft copolymer, wherein an azo-based initiator is introduced into the reactor at a weight ratio of 1:1 to 1:3 in the step of initiating the emulsion polymerization and the step of performing the emulsion polymerization.
The method of claim 6,
A method for producing a graft copolymer, wherein the aromatic vinyl monomer is introduced into the reactor in a weight ratio of 1:3 to 1:12 in the step of initiating the emulsion polymerization and the step of performing the emulsion polymerization.
The method of claim 6,
A method for producing a graft copolymer, wherein the vinyl cyanide-based monomer is introduced into the reactor at a weight ratio of 1:3 to 1:12 in the step of initiating the emulsion polymerization and the step of performing the emulsion polymerization.
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