KR20220010256A - Method for preparing graft copolymer - Google Patents

Abstract

The present invention relates to a method for preparing a graft copolymer which comprises the following steps of: putting a diene-based rubbery polymer and a first monomer mixture into a reactor and performing a first graft copolymerization; and putting a second monomer mixture into the reactor and performing a second graft copolymerization after the first graft copolymerization, wherein the first monomer mixture comprises a vinyl cyanide-based monomer and a vinyl aromatic monomer in a weight ratio of 6 : 4 to 9 : 1, and the second monomer mixture comprises a vinyl cyanide-based monomer and a vinyl aromatic monomer in a weight ratio of 1 : 9 to 4 : 6.

Description

Method for producing a graft copolymer {METHOD FOR PREPARING GRAFT COPOLYMER}

The present invention relates to a method for preparing a graft copolymer, and more particularly, to a method for preparing a graft copolymer having excellent flame retardancy, thermal stability, impact resistance and processability.

A graft copolymer including a diene-based rubbery polymer to which a vinyl cyanide-based monomer unit and a vinyl aromatic monomeric unit is grafted easily burns due to the characteristics of the diene-based rubbery polymer itself, and thus has poor flame retardancy. Since the thermoplastic resin composition including the graft copolymer also has poor flame retardancy, various methods for improving the flame retardancy of the thermoplastic resin composition have been proposed. Among them, the addition type is a simple mixing method by adding a flame retardant including a halogen-containing organic compound and a flame retardant auxiliary agent such as antimony oxide during the compounding process. Reactive type is a method of imparting flame retardancy by introducing a monomer capable of imparting flame retardancy to the main chain of the polymer to prepare a flame retardant polymer, or by introducing a reactive group to the polymer to chemically bond the flame retardant material to the terminal or side chain of the polymer. Among the addition type and the reaction type, the addition type is mainly used.

However, the thermoplastic resin composition including the graft copolymer has a problem in that as the addition amount of the halogen-containing organic compound increases, overall physical properties such as thermal stability, impact resistance, heat resistance and processability decrease.

Therefore, while minimizing the use of a flame retardant including a halogen-containing organic compound, a method for improving the flame retardancy is being studied.

KR1995-0009727A

The problem to be solved by the present invention is to provide a method for producing a graft copolymer excellent in flame retardancy, thermal stability, impact resistance and processability.

In order to solve the above problems, the present invention comprises the steps of introducing a diene-based rubber polymer and a first monomer mixture into a reactor and performing a first graft copolymerization; and adding a second monomer mixture to the reactor after the first graft copolymerization, and performing a second graft copolymerization, wherein the first monomer mixture is a vinyl cyanide-based monomer and a vinyl aromatic monomer 6: It contains a weight ratio of 4 to 9:1, and the second monomer mixture provides a method for preparing a graft copolymer comprising a vinyl cyanide-based monomer and a vinyl aromatic monomer in a weight ratio of 1:9 to 4:6 .

In addition, it is molded into a thermoplastic resin composition comprising a graft copolymer, and the flow index measured at 220° C. and 10 kg according to ASTM D1238 is 24-28 g/10 min. Impact strength measured according to ASTM D256 is 15 kg·cm/cm or more, the total combustion time for each pretreatment condition measured based on the UL-94 vertical combustion evaluation method is 21 seconds or less, and the retention heat discoloration degree according to the following formula 1 is 9 or less Provide a thermoplastic resin molded article do:

<Equation 1>

In the above formula, L ₁ ', a ₁ ' and b ₁ ' are L, a, and b of the first specimen prepared by directly injecting pellets prepared by extruding the thermoplastic resin composition in an injection machine set at 250 ° C. without dwelling CIE LAB It is a value measured in the color coordinate system,

L ₁₀ , a ₁₀ and b ₁₀ are the pellets prepared by extruding the thermoplastic resin composition, staying for 15 minutes in an injection machine set at 250 ° C., L, a, and b of the second specimen prepared by injection in the CIE LAB color coordinate system is a value measured with

According to the method for preparing the graft copolymer of the present invention, it is possible to prepare a graft copolymer having excellent flame retardancy, impact resistance, processability and thermal stability.

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.

The term 'diene-based rubber polymer' used in the present invention may refer to a diene-based monomer or a synthetic rubber prepared by cross-linking polymerization of a diene-based monomer and a vinyl aromatic monomer.

The diene-based monomer may be at least one selected from the group consisting of 1,3-butadiene, isoprene, chloroprene and piperylene, of which 1,3-butadiene is preferable.

The term 'vinyl aromatic monomer' used in the present invention includes styrene, α-methyl styrene, p-methyl styrene, 2,4-dimethyl styrene, 4-fluorostyrene, 4-chlorostyrene, 2-chlorostyrene, 4- It may mean at least one selected from the group consisting of bromostyrene and 2-bromostyrene. The vinyl aromatic monomer is preferably styrene.

The term 'vinyl cyanide-based monomer' used in the present invention may mean at least one selected from the group consisting of acrylonitrile, 2-methylacrylonitrile, 2-ethylacrylonitrile and 2-chloroacrylonitrile. can The vinyl cyanide-based monomer is preferably acrylonitrile.

The term 'average particle diameter' used in the present invention may mean an arithmetic average particle diameter in a particle size distribution measured by dynamic light scattering, specifically, an average particle diameter of scattering intensity. The average particle diameter can be measured using Nicomp 380 equipment (product name, manufacturer: PSS Nicomp).

1. Method for preparing graft copolymer

The method for producing a graft copolymer according to an embodiment of the present invention comprises the steps of: introducing a diene-based rubbery polymer and a first monomer mixture into a reactor and performing a first graft copolymerization; and adding a second monomer mixture to the reactor after the first graft copolymerization, and performing a second graft copolymerization, wherein the first monomer mixture is a vinyl cyanide-based monomer and a vinyl aromatic monomer 6: 4 to 9:1, and the second monomer mixture includes a vinyl cyanide-based monomer and a vinyl aromatic monomer in a weight ratio of 1:9 to 4:6.

The present inventors found that when the composition of the first monomer mixture and the second monomer mixture is adjusted in a specific ratio, the exposure of the diene-based rubber polymer, which is a factor that inhibits the flame retardancy, can be minimized, and thermal stability and impact resistance are improved, Accordingly, the present invention was completed.

Hereinafter, the present invention will be described in detail.

1) First graft copolymerization step

First, a diene-based rubbery polymer and a first monomer mixture are put into a reactor, and a first graft copolymerization is performed.

The diene-based rubbery polymer may have an average particle diameter of 50 to 500 nm, preferably 100 to 400 nm. When the above conditions are satisfied, a graft copolymer having excellent impact resistance and surface gloss can be prepared.

The content of the diene-based rubbery polymer may be 50 to 62 parts by weight, preferably 55 to 62 parts by weight, based on 100 parts by weight of the total of the diene-based rubbery polymer, the vinyl cyanide-based monomer and the vinyl aromatic monomer. When the above-mentioned range is satisfied, the impact resistance and surface gloss of the graft copolymer can be further improved.

The content of the vinyl cyanide-based monomer may be 5 to 15 parts by weight, preferably 7 to 12 parts by weight, based on 100 parts by weight of the total of the diene-based rubbery polymer, the vinyl cyanide-based monomer and the vinyl aromatic monomer. If the above-described range is satisfied, the chemical resistance of the graft copolymer may be improved.

The content of the vinyl aromatic monomer may be 25 to 35 parts by weight, preferably 27 to 15 parts by weight, based on 100 parts by weight of the total of the diene-based rubbery polymer, vinyl cyanide monomer, and vinyl aromatic monomer. When the above-described range is satisfied, the processability of the graft copolymer can be improved.

Here, 'sum of the diene-based rubbery polymer, vinyl cyanide-based monomer and vinyl aromatic monomer' may mean the total sum of the diene-based rubbery polymer, vinyl cyanide-based monomer and vinyl aromatic monomer added during polymerization. have.

The first monomer mixture contains a vinyl cyanide-based monomer and a vinyl aromatic monomer in a weight ratio of 6:4 to 9:1, and preferably contains a vinyl cyanide-based monomer and a vinyl aromatic monomer from 7:3 to 8: It may be included in a weight ratio of 2. When the above conditions are satisfied, exposure of the diene-based rubbery polymer to the outside can be minimized by adjusting the ratio of the monomers grafted to the diene-based rubbery polymer. If the vinyl cyanide-based monomer is included in less than the above-mentioned range, the flame retardancy improvement effect may be reduced. If the vinyl cyanide-based monomer is included in excess of the above-mentioned range, the weight average molecular weight may be remarkably reduced and impact resistance may be reduced.

The first monomer mixture may be continuously added for polymerization stability.

On the other hand, before the first graft copolymerization of the first monomer mixture to the diene-based rubbery polymer, the step of reacting the diene-based rubbery polymer with a monomolecular flocculant may be included.

When the diene-based rubbery polymer and the monomolecular flocculant are reacted, the small particle diameter diene-based rubbery polymer that reduces impact resistance and processability may aggregate with each other. In addition, since it is possible to reduce the inclusion of a vinyl cyanide-based monomer and a vinyl aromatic monomer in the diene-based rubbery polymer, polymerization of the monomers present in the diene-based rubbery polymer can be prevented, and the diene causing a decrease in impact resistance Swelling of the rubber-based polymer can be suppressed. In addition, since the cohesive force is weak compared to the polymer coagulant, it is possible to prevent the average particle diameter of the diene-based rubbery polymer from becoming too large.

The single molecule coagulant may be at least one selected from the group consisting of (meth)acrylic acid, lauryl (meth)acrylate, and stearyl (meth)acrylate, of which lauryl methacrylate is preferable.

The monomolecular flocculant may be added in an amount of 0.1 to 5 parts by weight, preferably 1 to 3 parts by weight, based on 100 parts by weight of the diene-based rubbery polymer. When the above-mentioned conditions are satisfied, the average particle diameter of the diene-based rubbery copolymer may be increased while polymerization stability is not destroyed by entanglement between the diene-based rubbery polymers.

The first graft copolymerization may be graft emulsion polymerization, and may be carried out at 50 to 85 °C or 60 to 80 °C, of which it is preferably carried out at 60 to 80 °C.

The first graft copolymerization may be performed in the presence of an initiator and an emulsifier.

The initiator is a radical initiator, and as a radical initiator, sodium persulfate, potassium persulfate, ammonium persulfate, hydrogen peroxide, t-butyl peroxide, t-butyl hydroperoxide, cumene hydroperoxide, p-mentane hydroperoxide, di- t-butyl peroxide, t-butyl cumyl peroxide, acetyl peroxide, isobutyl peroxide, octanoyl peroxide, dibenzoyl peroxide, 3,5,5-trimethylhexanol peroxide, t-butyl peroxyiso It may be at least one selected from the group consisting of butyrate, azobis isobutyronitrile, azobis-2,4-dimethylvaleronitrile, azobis cyclohexanecarbonitrile, and azobis isobutyric acid (butyric acid) methyl, among them t-butyl hydroperoxide is preferred.

The initiator may be present in an amount of 0.1 to 1.0 parts by weight, preferably 0.3 to 0.8 parts by weight, based on 100 parts by weight of the total of the diene-based rubbery polymer, the vinyl cyanide-based monomer and the vinyl aromatic monomer. If the above-mentioned range is satisfied, the residual amount of the initiator in the graft copolymer powder can be minimized while improving the polymerization stability of the graft polymerization.

In order to promote the initiation reaction together with the initiator, an activator may be further added. The activator may be at least one selected from the group consisting of sodium formaldehyde sulfoxylate, sodium ethylenediamine tetraacetate, iron (II) sulfate, dextrose, tetrasodium pyrophosphate, sodium pyrophosphate anhydiros and sodium sulfate. Among them, at least one selected from the group consisting of sodium ethylenediamine tetraacetate, iron(II) sulfate, and sodium aldehyde sulfoxylate is preferable.

The activator may be added in an amount of 0.001 to 0.5 parts by weight, preferably 0.01 to 0.3 parts by weight, based on 100 parts by weight of the total of the diene-based rubbery polymer, the vinyl cyanide-based monomer and the vinyl aromatic monomer. When the above-mentioned range is satisfied, the residual amount of the activator in the graft copolymer powder can be minimized while improving the polymerization stability of the graft polymerization.

The emulsifier is sodium dicyclohexyl sulfosuccinate, sodium di-(cyclohexyl)-sulfosuccinate, sodium dodecyl sulfate, sodium dodecyl benzene sulfonate, sodium octadecyl sulfate, sodium oleic sulfate, potassium dodecyl It may be at least one selected from the group consisting of sulfate, potassium octadecyl sulfate, potassium rosinate, and sodium rosinate.

The emulsifier may be added in an amount of 0.15 to 2.0 parts by weight, preferably 0.3 to 1.5 parts by weight, based on 100 parts by weight of the total of the diene-based rubbery polymer, the vinyl cyanide-based monomer and the vinyl aromatic monomer. When the above-described range is satisfied, it is possible to prepare a graft copolymer powder having a desired average particle diameter while improving polymerization stability of graft polymerization.

During the graft polymerization, a molecular weight modifier may be further added. The molecular weight modifier may be at least one selected from the group consisting of t-dodecyl mercaptan, n-dodecyl mercaptan and α-methylstyrene dimer, of which t-dodecyl mercaptan and α-methylstyrene dimer are desirable.

The molecular weight modifier may be added in an amount of 0.1 to 1.0 parts by weight, preferably 0.2 to 0.8 parts by weight, based on 100 parts by weight of the total of the diene-based rubbery polymer, vinyl cyanide-based monomer, and vinyl aromatic monomer. When the above-described range is satisfied, the first shell layer having a desired weight average molecular weight may be manufactured.

2) second graft copolymerization

Then, after the first graft copolymerization, a second monomer mixture is introduced into the reactor, and a second graft copolymerization is performed.

The second monomer mixture includes a vinyl cyanide-based monomer and a vinyl aromatic monomer in a weight ratio of 1:9 to 4:6, and preferably contains a vinyl cyanide-based monomer and a vinyl aromatic monomer in a weight ratio of 2:8 to 3: It may be included in a weight ratio of 7. When the above-mentioned conditions are satisfied, the production efficiency can be improved, and the dispersibility of the diene-based rubbery polymer in the graft copolymer can be improved. If the vinyl cyanide-based monomer is included in less than the above range, the final polymerization conversion rate is lowered, thereby increasing the content of the unreacted monomer, and thus the production efficiency may be reduced. If the vinyl cyanide-based monomer is included in excess of the above-mentioned range, the workability of the thermoplastic resin molded article prepared therefrom as well as the graft copolymer may be deteriorated.

Meanwhile, the weight ratio of the first monomer mixture to the second monomer mixture may be 1:9 to 4:6, preferably 2:8 to 3:7. When the above-mentioned range is satisfied, the final polymerization conversion rate can be increased, and the polymerization efficiency can be improved.

The second graft copolymerization may be carried out at 50 to 85 °C or 60 to 80 °C, of which it is preferably carried out at 60 to 80 °C.

The second graft copolymerization may be performed in the presence of at least one selected from the group consisting of an initiator, an activator, an emulsifier and a molecular weight modifier. The description of the initiator, the activator, the emulsifier and the molecular weight modifier is the same as described above.

When the second graft copolymerization is completed, in order to pulverize the graft copolymer latex, aggregation, aging, washing and drying processes may be further performed.

The agglomeration may be performed at 80 to 97 °C or 85 to 95 °C, of which 85 to 95 °C is preferable. When the above-described range is satisfied, a graft copolymer having a uniform particle shape and a small average particle diameter can be prepared, and thus a graft copolymer having uniform physical properties, particularly, impact resistance, can be prepared.

The aging may be performed at 50 to 98 °C, 80 to 98 °C, or 90 to 98 °C, of which it is preferably carried out at 90 to 98 °C. When the above-described range is satisfied, the bulk density is increased and the occurrence of the solidification phenomenon can be minimized.

The washing is performed to reduce foreign substances in the graft copolymer, and the graft copolymer powder can be prepared through dehydration and drying.

2. Thermoplastic resin molded products

A thermoplastic resin molded article according to another embodiment of the present invention is molded with a thermoplastic resin composition including the graft copolymer prepared by the method for producing a graft copolymer according to an embodiment of the present invention, and based on ASTM D1238, The flow index measured under 220 ° C and 10 kg conditions is 24-28 g/10 min, the impact strength measured according to ASTM D256 is 15 kg cm/cm or more, and measured according to the UL-94 vertical combustion evaluation method. The total burning time for each pretreatment condition is 21 seconds or less, and the retention heat discoloration degree according to Equation 1 is 9 or less:

<Equation 1>

In Equation 1, L ₁ ', a ₁ ' and b ₁ ' are L, a, and b of the first specimen prepared by directly injecting pellets prepared by extruding the thermoplastic resin composition in an injection machine set at 250 ° C. It is a value measured in the CIE LAB color coordinate system,

L ₁₀ , a ₁₀ and b ₁₀ are the pellets prepared by extruding the thermoplastic resin composition, staying for 15 minutes in an injection machine set at 250 ° C., L, a, and b of the second specimen prepared by injection in the CIE LAB color coordinate system is a value measured with

If the above conditions are satisfied, a thermoplastic resin molded article having excellent processability, impact resistance, flame retardancy and thermal stability may be manufactured. In addition, the thermoplastic resin molded article has a flow index of 25 to 28 g/10 min measured under conditions of 220 ° C and 10 kg according to ASTM D1238, and an impact strength of 18.5 kg cm / cm or more measured according to ASTM D256. , It is preferable that the total combustion time for each pretreatment condition measured based on the UL-94 vertical combustion evaluation method is 16 seconds or less, and the retention heat discoloration degree according to Equation 1 is 7 or less.

On the other hand, the thermoplastic resin composition including the graft copolymer prepared by the method for producing a graft copolymer according to an embodiment of the present invention is a non-graft copolymer including a vinyl aromatic monomer unit and a vinyl cyanide monomer unit. may include

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-mentioned range is satisfied, a thermoplastic resin composition having excellent processability and impact resistance can be manufactured.

The non-graft copolymer may include a vinyl cyanide-based monomer unit and a vinyl aromatic unit in a weight ratio of 40:60 to 20:80, preferably 35:65 to 25:75. When 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.

The thermoplastic resin composition of the present invention may further include at least one selected from the group consisting of a flame retardant, a flame retardant auxiliary, and an additive.

The flame retardant may be at least one selected from the group consisting of a bromine-based compound, a phosphonate ether-based compound, a phosphine, a phosphine oxide-based compound, and a phosphate-based compound, and among these, a bromine-based compound is preferably used.

The bromine-based compound is hexabromocyclododecane, tetrabromocyclooctane, monochloropentabromocyclohexane, decabromodiphenyl oxide, octabromodiphenyl oxide, decabromodiphenylethane, ethylenebis(tetrabromorph deimide), tetrabromobisphenol A, brominated epoxy oligomer, bis(tribromophenoxy)ethane, 2,4,6-tris(2,4,6-tribromophenoxy)-1, 3,5-triazine and tetrabromobisphenol A may be at least one selected from the group consisting of bis(allyl ether), of which 2,4,6-tris(2,4,6-tribromophenoxy) )-1,3,5-triazine is preferred.

The flame retardant may be included in an amount of 3 to 40 parts by weight, preferably 8 to 30 parts by weight, based on 100 parts by weight of the total of the graft copolymer and the non-graft copolymer. If the above-described range is satisfied, the property balance may be excellent while realizing high flame retardancy.

The flame retardant auxiliary agent may be at least one selected from the group consisting of antimony trioxide, biotite, muscovite, iron oxide, tungsten oxide and calcium carbonate, of which antimony trioxide is preferable.

The flame retardant auxiliary agent may be included in an amount of 0.5 to 10 parts by weight, preferably 1 to 8 parts by weight, based on 100 parts by weight of the total of the graft copolymer and the non-graft copolymer. If the above-described range is satisfied, the flame retardancy may be improved without deterioration of other physical properties.

The additives include lubricants, antioxidants, light stabilizers, hydrolysis stabilizers, mold release agents, pigments, antistatic agents, conductivity imparting agents, electromagnetic wave shielding materials, magnetism imparting agents, mineral fillers, crosslinking agents, antibacterial agents, processing aids, metal deactivators, flame retardants, It may be at least one selected from the group consisting of an anti-friction agent, an anti-wear agent, and a coupling agent.

The additive may be included in an amount of 0.5 to 5 parts by weight, preferably 1 to 3 parts by weight, based on 100 parts by weight of the total of the graft copolymer and the non-graft copolymer.

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.

Example 1

<Preparation of raw materials>

A first monomer mixture and a second monomer mixture were prepared by uniformly mixing acrylonitrile (AN) and styrene (ST) in the amounts shown in Table 1 below.

<Production of graft copolymer latex>

Polybutadiene rubber latex (PBL, average particle diameter: 310 nm, based on solid content) and 100 parts by weight of ion-exchanged water were sequentially added to the nitrogen-substituted polymerization reactor at the content shown in Table 1. Then, 1 part by weight of lauryl methacrylate was added to the polymerization reactor and stirred at 50° C. for 30 minutes.

In the polymerization reactor, 0.05 parts by weight of dextrose, 0.03 parts by weight of tetrasodium pyrophosphate, 0.001 parts by weight of iron (II) sulfate, and 0.12 parts by weight of cumene hydroperoxide were added in batches.

Polymerization was carried out while continuously introducing the first monomer mixture into the polymerization reactor at a constant rate for 25 minutes. After the addition of the first monomer mixture was completed, the second monomer mixture was continuously introduced into the polymerization reactor at a constant rate for 65 minutes. While the first monomer mixture and the second monomer mixture were continuously introduced, the internal temperature of the polymerization reactor was increased to 70° C. at a constant rate.

After the addition of the second monomer mixture was completed, 0.05 parts by weight of dextrose, 0.03 parts by weight of tetrasodium pyrophosphate, 0.001 parts by weight of iron (II) sulfate, and 0.05 parts by weight of cumene hydroperoxide were batched into the polymerization reactor, After polymerization while raising the temperature of the polymerization reactor to 80° C. over 1 hour, polymerization was terminated.

<Preparation of graft copolymer powder>

At 86 ℃, 100 parts by weight of the graft copolymer latex (based on solid content) was added to 2 parts by weight of magnesium sulfate, aged at 96 ℃ for 10 minutes, washed, dehydrated and dried to obtain a graft copolymer powder .

Examples 2 to 7, Comparative Examples 1 to 4

In Example 1, it was carried out in the same manner as in Example 1, except that the first and second monomer mixtures were added in the amounts shown in Tables 1 and 2 below.

Experimental Example 1

The physical properties of the graft copolymer latex of Examples and Comparative Examples were measured by the method described below, and the results are shown in Tables 1 and 2 below.

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

Polymerization conversion (%) = [(Total parts by weight of monomers, additives, and ion-exchanged water added during polymerization)/100 × measured value TSC]-(Parts by weight of additives)

(2) Amount of agglomeration (wt%): After filtering the graft copolymer latex using a 100 mesh net, it was put into a convention oven, and then left at 80 °C for 720 minutes. Then, the weight of the agglomerate caught in a 100 mesh net was measured and the amount of agglomeration of the graft copolymer latex was calculated according to the following formula.

Amount of agglomeration (wt%) = {(weight of agglomerate caught in a 100 mesh net)/(theoretical total weight of butadiene rubber polymer, styrene, acrylonitrile and additives added during the preparation of the graft copolymer)} × 100

Experimental Example 2

25 parts by weight of the graft copolymer powder of Examples and Comparative Examples, 75 parts by weight of a styrene/acrylonitrile non-graft copolymer (95RF of LG Chem), a flame retardant (2,4,6-tris(2,4,6) -Bromophenoxy)-1,3,5-triazine) 18 parts by weight, flame retardant auxiliary (antimony trioxide) 3 parts by weight, lubricant (ethylene bis stearamide) 1.5 parts by weight, stabilizer (IRGANOX 1076 from BASF) 0.3 After uniformly mixing 0.1 parts by weight of anti-drip agent (polytetrafluoroethylene) with a Henschel mixer, extrusion was performed to prepare pellets. And, the physical properties were evaluated by the following method, and the results are shown in Tables 1 and 2 below.

(1) Melt Flow Index (g/10 min): It was measured under the conditions of 220 °C and 10 kg in accordance with ASTM D1238.

(2) Izod impact strength (kg·cm/cm, 1/4 In): After preparing a specimen by injecting the pellets, it was measured according to ASTM D256.

(3) Total burning time (t1 + t2, sec) by pretreatment condition: Based on the UL-94 vertical combustion evaluation method, the pellets were injected to prepare a specimen (thickness: 2.5 mm, width: 12.7 mm, length: 127 mm) After manufacturing, the total combustion time for each pretreatment condition was measured.

(4) Retention heat discoloration degree: The retention heat discoloration degree was calculated according to Equation 1 below.

<Equation 1>

In Equation 1, L ₁ ', a ₁ ', and b ₁ ' are the pellets prepared by extruding the thermoplastic resin compositions of Examples and Comparative Examples, L of the first specimen prepared by directly injecting without residence in an injection machine set at 250 ° C. , a and b are the values measured in the CIE LAB color coordinate system,

L ₁₀ , a ₁₀ and b ₁₀ are the pellets prepared by extruding the thermoplastic resin compositions of Examples and Comparative Examples, after staying for 15 minutes in an injection machine set at 250 ° C., L, a and b of the second specimen prepared by injection is the value measured by the CIE LAB color coordinate system.

division Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Example 7 Polybutadiene latex (parts by weight) 60 60 60 60 60 60 60 first monomer mixture
(parts by weight) AN 6 7 8 9 7 7 7 ST 4 3 2 One 3 3 3 AN:ST (weight ratio) 6:4 7:3 8:2 9:1 7:3 7:3 7:3 second monomer mixture
(parts by weight) AN 9 9 9 9 3 6 12 ST 21 21 21 21 27 24 18 AN:ST (weight ratio) 3:7 3:7 3:7 3:7 1:9 2:8 4:6 final polymerization conversion 96.5 98.2 97.6 95.6 96.8 97.9 96.5 clot 0.15 0.10 0.13 0.21 0.3 0.19 0.14 flow index 25.9 27.6 26.1 24.5 26.0 26.6 25.7 impact strength 16.1 21.1 19.4 15.2 22.0 21.5 18.7 Burning time by pretreatment condition 10 3 8 12 21 16 15 retention heat discoloration 7.2 4 5.4 8.9 7.5 6.5 6.9

division Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Polybutadiene Latex (parts by weight) 60 60 60 60 first monomer mixture
(parts by weight) AN 5 9.5 One 5 ST 5 0.5 9 5 AN:ST (weight ratio) 5:5 9.5:0.5 1:9 5:5 second monomer mixture
(parts by weight) AN 9 9 15 15 ST 21 21 15 15 AN:ST (weight ratio) 3:7 3:7 5:5 5:5 final polymerization conversion 96.5 98.2 97.5 97.1 clot 0.24 0.23 0.16 0.26 flow index 26.5 13.2 27.0 22.4 impact strength 15.0 14.3 16.8 17.0 Burning time by pretreatment condition 15 19 35 20 Retention heat discoloration 12.1 9.2 15.3 16.1

Referring to Tables 1 and 2, the thermoplastic resin compositions of Examples 1 to 7 have an appropriate flow index, high impact strength, short combustion time for each pretreatment condition, and low retention heat discoloration, so that processability, Impact resistance, flame retardancy and thermal stability were all excellent. Among these, the thermoplastic resin compositions of Examples 2 and 3 using the first monomer mixture containing acrylonitrile and styrene as an optimum content had a remarkably short combustion time for each pretreatment condition and a remarkably low retention heat discoloration. , flame retardancy and thermal stability were particularly excellent. And, the thermoplastic resin composition of Example 6 using the second monomer mixture containing acrylonitrile and styrene as an optimum content had high impact strength and a short combustion time for each pretreatment condition, so it was particularly excellent in impact resistance and flame retardancy.

On the other hand, Comparative Example 1 using the first monomer mixture containing acrylonitrile and styrene in a weight ratio of 5:5 had a high degree of retention thermochromism, so the thermal stability was not excellent.

Comparative Example 2 using the first monomer mixture containing acrylonitrile and styrene in a weight ratio of 9.5:0.5 had high flow index, impact strength, and retention heat discoloration, so processability, impact resistance and thermal stability were not excellent. .

Comparative Example 3 using a first monomer mixture containing acrylonitrile and styrene in a weight ratio of 1:9 and a second monomer mixture containing acrylonitrile and styrene in a weight ratio of 5:5 had a long burning time for each pretreatment condition , due to high retention heat discoloration, flame retardancy and thermal stability were not excellent.

Comparative Example 4 using a first monomer mixture containing acrylonitrile and styrene in a weight ratio of 5:5 and a second monomer mixture containing acrylonitrile and styrene in a weight ratio of 5:5 had high retention heat discoloration. , the thermal stability was not excellent.

Claims (10)

adding a diene-based rubbery polymer and a first monomer mixture to a reactor and performing a first graft copolymerization; and
After the first graft copolymerization, adding a second monomer mixture to the reactor, and performing a second graft copolymerization;
The first monomer mixture comprises a vinyl cyanide-based monomer and a vinyl aromatic monomer in a weight ratio of 6:4 to 9:1,
The second monomer mixture is a method for producing a graft copolymer comprising a vinyl cyanide-based monomer and a vinyl aromatic monomer in a weight ratio of 1:9 to 4:6.
The method according to claim 1,
The first monomer mixture includes a vinyl cyanide-based monomer and a vinyl aromatic monomer in a weight ratio of 7:3 to 8:2.
The method according to claim 1,
The second monomer mixture includes a vinyl cyanide-based monomer and a vinyl aromatic monomer in a weight ratio of 2:8 to 3:7, the method for producing a graft copolymer.
The method according to claim 1,
The weight ratio of the first monomer mixture to the second monomer mixture is 1:9 to 4:6.
The method according to claim 1,
Before the first graft copolymerization step, the method for producing a graft copolymer comprising the step of reacting the diene-based rubbery polymer and a monomolecular flocculant.
6. The method of claim 5,
The monomolecular flocculant is (meth) acrylic acid, lauryl (meth) acrylate, a method of producing a graft copolymer comprising at least one selected from the group consisting of stearyl (meth) acrylate.
6. The method of claim 5,
The method for producing a graft copolymer that the monomolecular flocculant is added in an amount of 0.1 to 5 parts by weight based on 100 parts by weight of the diene-based rubbery copolymer.
Molded into a thermoplastic resin composition comprising a graft copolymer,
According to ASTM D1238, the flow index measured under 220 °C and 10 kg conditions is 24-28 g/10 min,
The impact strength measured according to ASTM D256 is 15 kg·cm/cm or more,
The total combustion time for each pretreatment condition measured according to the UL-94 vertical combustion evaluation method is 21 seconds or less,
A thermoplastic resin molded article having a retention heat discoloration degree of 9 or less according to the following formula:
<Equation 1>

In Equation 1, L ₁ ', a ₁ ' and b ₁ ' are L, a, and b of the first specimen prepared by directly injecting pellets prepared by extruding the thermoplastic resin composition in an injection machine set at 250 ° C. It is a value measured in the CIE LAB color coordinate system,
L ₁₀ , a ₁₀ and b ₁₀ are the pellets prepared by extruding the thermoplastic resin composition, staying for 15 minutes in an injection machine set at 250 ° C., L, a, and b of the second specimen prepared by injection in the CIE LAB color coordinate system is a value measured with
9. The method of claim 8,
The thermoplastic resin molded article is
According to ASTM D1238, the flow index measured at 220 °C and 10 kg is 25 to 28 g/10 min,
The impact strength measured according to ASTM D256 is 18.5 kg·cm/cm or more,
The total combustion time for each pretreatment condition measured according to the UL-94 vertical combustion evaluation method is 16 seconds or less,
A thermoplastic resin molded article having a retention heat discoloration degree of 7 or less according to Equation 1 above.
9. The method of claim 8,
The thermoplastic resin composition is a thermoplastic resin molded article comprising a non-graft copolymer comprising a vinyl cyanide-based monomer unit and a vinyl aromatic monomer unit.