Patent Description:
Vinyl chloride-based resins are cheap, are easy to control hardness, have various application fields, have excellent physical properties and chemical properties, and are widely used in various fields. However, the vinyl chloride-based resins themselves have structurally inferior impact resistance, processing liquidity, heat resistant deformation, etc., and for commercialization, the use of additives for supplementing the defects of the vinyl chloride-based resins is essential, and among the additives, an impact reinforcing agent is necessary.

As the impact reinforcing agent available in the vinyl chloride-based resins, a thermoplastic polymer-based impact reinforcing agent such as an methylmethacrylate-butadiene-styrene (MBS)-based impact reinforcing agent, an acrylic impact reinforcing agent, chlorinated polyethylene (CPE), and ethylene vinyl acetate (EVA); and an inorganic impact reinforcing agent such as calcium carbonate coated with stearic acid, may be used, and among them, the MBS-based impact reinforcing agent and the acrylic impact reinforcing agent are mostly used.

Recently, a butadiene-based impact reinforcing agent is mostly used for the usage of interior, deco sheets, and flooring materials of building structures, and according to the purpose of use, dispersibility during processing, adhesion in a roll mill, and thermal stability are required as well as impact strength.

Particularly, in the case where a refractive index is controlled with a vinyl chloride-based resin, the MBS-based impact reinforcing agent may be used in transparent products such as toy packaging, and has advantages of using in opaque products such as a credit card by increasing the content of butadiene. However, recently, due to the whitening phenomenon by the impact reinforcing agent, there have been calls for reducing the content of the impact reinforcing agent, and accordingly, efforts to secure the impact strength, while improving the whitening phenomenon by the impact reinforcing agent are continuing.

However, since the MBS-based reinforcing agent has the trade off relation between impact strength and whitening properties, the improvement of the impact strength and the whitening properties at once is difficult. Accordingly, a method of introducing a silicone-based oil used in the preparation process of acrylonitrile-butadiene-styrene (ABS) during preparing an MBS-based impact reinforcing agent has been suggested. The silicone-based oil forms a soft domain in a butadiene rubber and may improve impact strength, and accordingly, if applied to a vinyl chloride-based resin, impact strength may increase. However, at the same time, there are problems in that whitening phenomenon rapidly rises, and the application thereof becomes impossible.

The present invention has been made to solve the above-described problems of the conventional technique, and has an object of improving impact strength, while maintaining whitening properties to equal or better levels, when a graft copolymer is applied to a vinyl chloride-based resin as an impact reinforcing agent.

In addition, another object of the present invention is to reinforcing entanglement between a vinyl chloride-based resin and a graft copolymer, reducing energy from external stress, and minimizing the deformation of a molded article, when a graft copolymer is applied to a vinyl chloride-based resin as an impact reinforcing agent.

In order to solve the above-described tasks, the present invention provides a graft copolymer including a rubbery polymer, wherein the rubbery polymer includes a conjugated diene-based monomer unit, and a soft domain, the graft copolymer includes an alkyl (meth)acrylate-based monomer unit, an aromatic vinyl-based monomer unit, and an alkali metal sulfonate-based monomer unit, wherein the graft copolymer comprises a graft layer comprising the alkyl (meth)acrylate-based monomer unit, the aromatic vinyl-based monomer unit and the alkali metal sulfonate-based monomer unit, which are grafted into the rubbery polymer, the soft domain is formed by including a mineral-based oil, the mineral-based oil includes <NUM> wt% to <NUM> wt% of a mineral oil and <NUM> wt% to <NUM> wt% of a silicone-based oil, the mineral-based oil is included in <NUM> parts by weight to <NUM> parts by weight based on <NUM> parts by weight of the rubbery polymer, and the alkali metal sulfonate-based monomer unit is included in <NUM> wt% to <NUM> wt% based on the graft copolymer.

In addition, the present invention provides a method for preparing a graft copolymer including: injecting and polymerizing a conjugated diene-based monomer and a mineral-based oil to prepare a rubbery polymer latex including a rubbery polymer (S10); injecting an alkyl (meth)acrylate-based monomer and an alkali metal sulfonate-based monomer in the presence of the rubbery polymer latex prepared in step (S10), and graft polymerizing to prepare a graft copolymer latex including a graft copolymer (S20); and injecting an aromatic vinyl-based monomer in the presence of the graft copolymer latex prepared in step (S20) and secondly graft polymerizing (S30), wherein the mineral-based oil includes <NUM> wt% to <NUM> wt% of a mineral oil and <NUM> wt% to <NUM> wt% of a silicone-based oil, the mineral-based oil is injected in <NUM> parts by weight to <NUM> parts by weight based on <NUM> parts by weight of the conjugated diene-based monomer, and the alkali metal sulfonate-based monomer is injected in <NUM> wt% to <NUM> wt% based on the rubbery polymer and a total monomer amount injected.

In addition, the present invention provides a resin composition including the graft copolymer, and a vinyl chloride-based resin.

In case of applying the graft copolymer of the present invention in a vinyl chloride-based resin as an impact reinforcing agent, improving effects may be achieved, while maintaining the whitening properties of a resin composition to equal or better levels.

In addition, in case of applying the graft copolymer of the present invention in a vinyl chloride-based resin as an impact reinforcing agent, entanglement between the vinyl chloride-based resin and the graft copolymer may be reinforced, energy from external stress may be reduced, and effects of minimizing the deformation of a molded article may be achieved.

In addition, the resin composition of the present invention includes the graft copolymer, and whitening properties may be maintained to equal or better levels, and effects of excellent impact strength and minimizing the deformation of a molded article may be achieved.

<FIG> is a photographic image by transmission electron microscope (TEM) of a rubbery material including a soft domain formed by including a mineral-based oil, in a graft copolymer according to an embodiment of the present invention.

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

It will be understood that words or terms used in the description and claims of the present invention shall not be interpreted as the meaning defined in commonly used dictionaries. It will be understood that the words or terms should be interpreted as having a meaning that is consistent with their meaning in the technical idea of the invention, based on the principle that an inventor may properly define the meaning of the words to best explain the invention.

The term "monomer unit" in the present invention may represent a component or a structure derived from the monomer or the material itself, in a particular embodiment, may mean a repeating unit formed in the polymer during polymerizing a polymer through the participation of the monomer injected in polymerization reaction.

The term "composition" used in the present invention includes a reaction product and a decomposition product formed from the materials of a corresponding composition as well as a mixture of materials including the corresponding composition.

The present invention provides a graft copolymer which may be used as an impact reinforcing agent. The graft copolymer is a graft copolymer including a rubbery polymer, wherein the rubbery polymer includes a conjugated diene-based monomer unit, and a soft domain, the graft copolymer includes an alkyl (meth)acrylate-based monomer unit, an aromatic vinyl-based monomer unit, and an alkali metal sulfonate-based monomer unit, wherein the graft copolymer comprises a graft layer comprising the alkyl (meth)acrylate-based monomer unit, the aromatic vinyl-based monomer unit and the alkali metal sulfonate-based monomer unit, which are grafted into the rubbery polymer, the soft domain is formed by including a mineral-based oil, the mineral-based oil includes <NUM> wt% to <NUM> wt% of a mineral oil and <NUM> wt% to <NUM> wt% of a silicone-based oil, the mineral-based oil is included in <NUM> parts by weight to <NUM> parts by weight based on <NUM> parts by weight of the rubbery polymer, and the alkali metal sulfonate-based monomer unit is included in <NUM> wt% to <NUM> wt% based on the graft copolymer.

According to an embodiment of the present invention, the mineral-based oil may be included in <NUM> parts by weight to <NUM> parts by weight, <NUM> parts by weight to <NUM> parts by weight, <NUM> parts by weight to <NUM> parts by weight, or <NUM> parts by weight to <NUM> parts by weight based on <NUM> parts by weight of the rubbery polymer. If the mineral-based oil is included in less than <NUM> parts by weight, the soft domain may be insufficiently formed in the rubbery polymer, and impact strength may be degraded, and if the mineral-based oil is included in greater than <NUM> parts by weight, and if the silicone-based oil is included together, there are problems in that the absolute amount of the silicone-based oil increases, and whitening properties are degraded.

In addition, according to an embodiment of the present invention, the mineral-based oil may include <NUM> wt% to <NUM> wt% of a mineral oil and <NUM> wt% to <NUM> wt% of a silicone-based oil, <NUM> wt% to <NUM> wt% of a mineral oil and <NUM> wt% to <NUM> wt% of a silicone-based oil, or <NUM> wt% to <NUM> wt% of a mineral oil and <NUM> wt% to <NUM> wt% of a silicone-based oil. If the silicone-based oil is included in the mineral-based oil in greater than <NUM> wt%, there are problems in that the absolute amount of the silicone-based oil increases, and whitening properties are degraded.

According to an embodiment of the present invention, the mineral oil may include a hydrocarbon of less than <NUM> carbon atoms, in a particular embodiment, a mixture of alkane of less than <NUM> carbon atoms, which is present in a liquid state at room temperature, and may include paraffin according to circumstances. The mineral oil may be a colorless, odorless oil extracted from petroleum. The mineral oil may have a commercially available viscosity of <NUM> cs to <NUM>,<NUM> cs.

According to an embodiment of the present invention, the silicone-based oil may be polydimethylsiloxane. In a particular embodiment, the silicone-based oil may be a polydimethylsiloxane oil having a commercially available kinetic viscosity of <NUM> cs to <NUM>,<NUM> cs.

According to an embodiment of the present invention, the conjugated diene-based monomer unit is for providing a graft copolymer with impact resistance, and a conjugated diene-based monomer forming the conjugated diene-based monomer unit may be one or more selected from the group consisting of <NUM>,<NUM>-butadiene, <NUM>,<NUM>-dimehtyl-<NUM>,<NUM>-butadiene, piperylene, <NUM>-butyl-<NUM>,<NUM>-octadiene, isoprene and <NUM>-phenyl-<NUM>,<NUM>-butadiene, particularly, <NUM>,<NUM>-butadiene.

According to an embodiment of the present invention, the rubbery polymer may include an aromatic vinyl-based monomer unit. The aromatic vinyl-based monomer unit is for providing a graft copolymer with transparency, and an aromatic vinyl-based monomer forming the aromatic vinyl-based monomer unit may be one or more selected from the group consisting of styrene, α-methylstyrene, <NUM>-methylstyrene, <NUM>-methylstyrene, <NUM>-propylstyrene, <NUM>-vinylnaphthalene, <NUM>-cyclohexylstyrene, <NUM>-(p-methylphenyl)styrene and <NUM>-vinyl-<NUM>-hexylnaphthalene, particularly, styrene.

According to an embodiment of the present invention, if the rubbery polymer includes the aromatic vinyl-based monomer unit, the conjugated diene-based monomer unit may be <NUM> wt% to <NUM> wt%, <NUM> wt% to <NUM> wt%, or <NUM> wt% to <NUM> wt% based on the rubbery polymer, and within this range, effects of excellent impact strength may be obtained. In addition, if the rubbery polymer includes the aromatic vinyl-based monomer unit, the aromatic vinyl-based monomer unit may be <NUM> wt% to <NUM> wt%, <NUM> wt% to <NUM> wt%, or <NUM> wt% to <NUM> wt% based on the rubbery polymer, and within this range, transparency is excellent, and effects of controlling refractive index according to a vinyl chloride-based resin may be obtained.

According to an embodiment of the present invention, the content of the rubbery polymer may be <NUM> wt% to <NUM> wt%, <NUM> wt% to <NUM> wt%, or <NUM> wt% to <NUM> wt% based on the graft copolymer, and within this range, effects of the improving impact strength may be achieved, while maintaining whitening properties of a resin composition including the graft copolymer as an impact reinforcing agent to equal or better levels.

According to an embodiment of the present invention, the average particle diameter of the rubbery polymer may be <NUM> to <NUM> nm, <NUM> to <NUM>, or <NUM> to <NUM>, and within this range, effects of improving impact strength may be achieved, while maintaining whitening properties of a resin composition including the graft copolymer as an impact reinforcing agent to equal or better levels.

According to an embodiment of the present invention, the alkyl (meth)acrylate-based monomer unit is for providing a graft copolymer with transparency and improving compatibility with a vinyl chloride-based resin, and an alkyl (meth)acrylate-based monomer forming the alkyl (meth)acrylate-based monomer unit may be an alkyl (meth)acrylate-based monomer of <NUM> to <NUM> carbon atoms, and in a particular embodiment, a mixture of a methyl (meth)acrylate monomer; and one or more monomers selected from the group consisting of alkyl (meth)acrylate monomers of <NUM> to <NUM> carbon atoms, more particularly, a mixture of a methyl methacrylate; and one or more selected from the group consisting of alkyl acrylates of <NUM> to <NUM> carbon atoms.

According to an embodiment of the present invention, in the case where the alkyl (meth)acrylate-based monomer is the mixture of a methyl (meth)acrylate-based monomer; and one or more monomers selected from the group consisting of alkyl (meth)acrylate-based monomers of <NUM> to <NUM> carbon atoms, the weight ratio of the methyl (meth)acrylate-based monomer; and the one or more monomers selected from the group consisting of and alkyl (meth)acrylate-based monomers of <NUM> to <NUM> carbon atoms may be <NUM> to <NUM>:<NUM>, <NUM> to <NUM>:<NUM>, or <NUM> to <NUM>:<NUM>, and within this range, the high reactivity of the methyl (meth)acrylate-based monomer may be controlled, and at the same time, the alkyl (meth)acrylate-based monomer unit of <NUM> to <NUM> carbon atoms may be formed between the methyl (meth)acrylate-based monomer units, and effects that the graft layer of a graft copolymer shows a uniform molecular weight may be achieved.

According to an embodiment of the present invention, the content of the alkyl (meth)acrylate-based monomer unit may be <NUM> wt% to <NUM> wt%, <NUM> wt% to <NUM> wt%, or <NUM> wt% to <NUM> wt% based on the graft copolymer, and within this range, effects of excellent transparency and compatibility of the graft copolymer may be achieved.

According to an embodiment of the present invention, the aromatic vinyl-based monomer unit is for providing a graft copolymer with compatibility, and an aromatic vinyl-based monomer forming the aromatic vinyl-based monomer unit may be one or more selected from the group consisting of styrene, α-methylstyrene, <NUM>-methylstyrene, <NUM>-methylstyrene, <NUM>-propylstyrene, <NUM>-vinylnaphthalene, <NUM>-cyclohexylstyrene, <NUM>-(p-methylphenyl)styrene and <NUM>-vinyl-<NUM>-hexylnaphthalene, particularly, styrene.

According to an embodiment of the present invention, the content of the aromatic vinyl-based monomer unit may be <NUM> wt% to <NUM> wt%, <NUM> wt% to <NUM> wt%, or <NUM> wt% to <NUM> wt% based on the graft copolymer, and within this range, excellent effects of compatibility of the graft copolymer may be obtained.

According to an embodiment of the present invention, the alkali metal sulfonate-based monomer may be sodium methylallyl sulfonate. Like this, if the graft copolymer includes the alkali metal sulfonate-based monomer unit, the graft copolymer includes ionic bonds present in the alkali metal sulfonate-based monomer, and glass transition temperature may increase, heat resistant properties may be improved, and entanglement between a vinyl chloride-based resin and a graft copolymer may be reinforced. Accordingly, energy from external stress may be reduced, and effects of minimizing the deformation of a molded article may be obtained. In addition, since the ionic bonds may perform the function of a reactive emulsifier, improving effects of the stability of a latex during preparing a graft copolymer may be achieved.

According to an embodiment of the present invention, the content of the alkali metal sulfonate-based monomer unit may be <NUM> wt% to <NUM> wt%, <NUM> wt% to <NUM> wt%, <NUM> wt% to <NUM> wt%, or <NUM> wt% to <NUM> wt% based on the graft copolymer. If the amount of the alkali metal sulfonate-based monomer unit is less than <NUM> wt%, the weight average molecular weight of the graft layer of the graft copolymer may be insufficiently increased, and the graft layer is insufficiently formed, and dispersibility is deteriorated, and accordingly, there are problems of reducing impact resistance as well as processability. If the content is greater than <NUM> wt%, during preparing a graft copolymer dry powder, phase separation between a graft copolymer and water is not generated on a latex, and the dry powder could not be prepared.

According to the present invention, in the case where the graft copolymer includes the rubbery polymer, the alkyl (meth)acrylate-based monomer unit, the aromatic vinyl-based monomer unit and the alkali metal sulfonate-based monomer unit, a graft layer including grafted alkyl (meth)acrylate-based monomer unit, aromatic vinyl-based monomer unit and alkali metal sulfonate-based monomer unit into the rubbery polymer is included.

In addition, according to an embodiment of the present invention, the graft layer may have a weight average molecular weight of <NUM>,<NUM>/mol to <NUM>,<NUM>/mol, <NUM>,<NUM>/mol to <NUM>,<NUM>/mol, <NUM>,<NUM>/mol to <NUM>,<NUM>/mol, or <NUM>,<NUM>/mol to <NUM>,<NUM>/mol, and within this range, entanglement between a vinyl chloride-based resin and a graft copolymer may be reinforced, energy from external stress may be reduced, and effects of minimizing the deformation of a molded article may be achieved. In addition, since the ionic bonds may also perform the function of a reactive emulsifier, during preparing a graft copolymer, effects of improving latex stability may be obtained.

In addition, according to an embodiment of the present invention, the average particle diameter of the graft copolymer may be <NUM> to <NUM>, <NUM> to <NUM>, or <NUM> to <NUM>, and within this range, effects of improving impact resistance may be achieved, while maintaining whitening properties of a resin composition including the graft copolymer as an impact reinforcing agent to equal or better levels.

The present invention provides a method for preparing the graft copolymer. The method for preparing the graft copolymer includes: injecting and polymerizing a conjugated diene-based monomer and a mineral-based oil to prepare a rubbery polymer latex including a rubbery polymer (S10); injecting an alkyl (meth)acrylate monomer and an alkali metal sulfonate-based monomer in the presence of the rubbery polymer latex prepared in step (S10) and graft polymerizing to prepare a graft copolymer latex including a graft copolymer (S20); and injecting an aromatic vinyl-based monomer in the presence of the graft copolymer latex prepared in step (S20) and secondly graft polymerizing (S30), wherein the mineral-based oil includes <NUM> wt% to <NUM> wt% of a mineral oil and <NUM> wt% to <NUM> wt% of a silicone-based oil, the mineral-based oil is injected in <NUM> parts by weight to <NUM> parts by weight based on <NUM> parts by weight of the conjugated diene-based monomer, and the alkali metal sulfonate-based monomer is injected in <NUM> wt% to <NUM> wt% based on the rubbery polymer and a total monomer amount injected.

According to an embodiment of the present invention, step (S10) is a step for preparing a rubbery polymer and may be a step of polymerizing a conjugated diene-based monomer. Here, the conjugated diene-based monomer may be the same as the monomer for forming the conjugated diene-based monomer unit and the aromatic vinyl-based monomer unit of the above-described rubbery polymer. In addition, the conjugated diene-based monomer may be injected in the same amount as the above-described amount of the conjugated diene-based monomer unit of the rubbery polymer.

According to an embodiment of the present invention, step (S10) may be performed by emulsion polymerization, and accordingly, the rubbery polymer may be obtained in a rubbery polymer latex type including the rubbery polymer.

According to an embodiment of the present invention, step (S10) may be performed by radical polymerization using a peroxide-based, redox, or azo-based initiator, and the redox initiator may be, for example, one or more selected from the group consisting of t-butyl hydroperoxide, diisopropylbenzene hydroperoxide and cumene hydroperoxide. In this case, effects of providing stable polymerization environment may be obtained.

In addition, according to an embodiment of the present invention, in case of using the redox initiator, ferrous sulfate, sodium ethylenediaminetetraacetate and sodium formaldehyde sulfoxylate may be further included as the redox catalyst.

In addition, according to an embodiment of the present invention, an emulsifier used for emulsion polymerization in step (S10) may be one or more selected from the group consisting of an anionic emulsifier, a cationic emulsifier and a nonionic emulsifier, and particular embodiments may include one or more selected from the group consisting of alkylaryl sulfonate, alkali methyl alkylsulfate, a soap of fatty acid, an oleic acid alkali salt, a rosin acid alkali salt, a lauryl acid alkali salt, sodium diethylhexyl phosphate, a phosphonated polyoxyethylene alcohol and phosphonated polyoxyethylene phenol, and in this case, effects of providing stable polymerization environment may be obtained. The emulsifier may be injected in, for example, <NUM> parts by weight or less, <NUM> parts by weight or less, or <NUM> parts by weight to <NUM> parts by weight based on <NUM> parts by weight of the total amount of the monomers injected in step (S10).

According to an embodiment of the present invention, the emulsion polymerization in step (S10) may be performed in an aqueous solvent, and the aqueous solvent may be ion exchange water.

In addition, according to an embodiment of the present invention, step (S10) may be performed by further including an aromatic vinyl-based monomer. Here, the aromatic vinyl-based monomer may be the same as the monomer for forming the aromatic vinyl-based monomer unit of the rubbery polymer described above. In addition, the aromatic vinyl-based monomer may be injected in the same amount as that of the aromatic vinyl-based monomer unit of the rubbery polymer described above.

According to an embodiment of the present invention, the emulsion polymerization in step (S10) may be performed by injecting a mineral-based oil together with the conjugated diene-based monomer. In this case, the mineral-based oil may form a soft domain between chains formed by the conjugated diene-based monomer units in the rubbery polymer during forming the rubbery polymer by the polymerization of the conjugated diene-based monomer. Here, the mineral-based oil may be the same as the above-described mineral-based oil. In addition, the mineral-based oil may be injected in the same amount as the amount of the above-described mineral-based oil of the rubbery polymer.

According to an embodiment of the present invention, step (S20) is a step for preparing a graft copolymer, and may be a step for graft polymerizing an alkyl (meth)acrylate-based monomer and an alkali metal sulfonate-based monomer. Here, the alkyl (meth)acrylate-based monomer may be the same as the above-described monomer for forming the alkyl (meth)acrylate-based monomer unit of the graft copolymer. In addition, the alkyl (meth)acrylate-based monomer may be injected in the same amount as the above-described amount of the alkyl (meth)acrylate-based monomer unit of the graft copolymer. In addition, here, the alkali metal sulfonate-based monomer may be the same as the above-described monomer for forming the alkali metal sulfonate-based monomer unit of the graft copolymer. In addition, the alkali metal sulfonate-based monomer may be injected in the same amount as the above-described amount of the alkali metal sulfonate-based monomer unit of the graft copolymer.

In addition, according to an embodiment of the present invention, the preparation method of the graft copolymer may include injecting an aromatic vinyl-based monomer in the presence of the graft copolymer latex prepared in step (S20) and secondly graft polymerizing (S30).

According to an embodiment of the present invention, step (S30) may be performed by injecting an aromatic vinyl-based monomer in an incre injection method, and accordingly, a molecular weight may be controlled small, and the aromatic vinyl-based monomers enter between graft layers formed from the alkyl (meth)acrylate-based monomer and the alkali metal sulfonate-based monomer to achieve a stable state from an unstable state of the alkyl (meth)acrylate monomer, and thus, the stability of a latex is improved, and at the same time, effects of improving whitening properties may be obtained. Here, the aromatic vinyl-based monomer may be the same as the monomer for forming the above-described aromatic vinyl-based monomer unit of the graft copolymer. In addition, the aromatic vinyl-based monomer may be injected in the same amount as the amount of the above-described aromatic vinyl-based monomer unit of the graft copolymer.

According to an embodiment of the present invention, the graft polymerization in step (S20) and step (S30) may be performed by emulsion polymerization, and accordingly, the graft copolymer may be obtained in a graft copolymer latex type including the graft copolymer.

According to an embodiment of the present invention, the graft polymerization in step (S20) and step (S30) may be performed by radical polymerization using a peroxide-based, redox, or azo-based initiator, and the redox initiator may be, for example, one or more selected from the group consisting of t-butyl hydroperoxide, diisopropylbenzene hydroperoxide and cumene hydroperoxide. In this case, effects of providing stable polymerization environment may be obtained.

In addition, according to an embodiment of the present invention, the graft polymerization in step (S20) and step (S30) may be performed without injecting an emulsifier. In a particular embodiment, since the alkali metal sulfonate-based monomer injected in step (S20) shows ionic characteristics by itself and may play the role of a reactive emulsifier as a monomer, simultaneously, and accordingly, the graft polymerization may be performed without injecting an extra emulsifier.

According to an embodiment of the present invention, the graft polymerization in step (S20) and step (S30) may be performed in an aqueous solvent, and the aqueous solvent may be ion exchange water.

In addition, the present invention provides a resin composition including the graft copolymer and a vinyl chloride-based resin.

According to an embodiment of the present invention, the resin composition may be a vinyl chloride-based resin composition including the graft copolymer as an impact reinforcing agent.

According to an embodiment of the present invention, the resin composition may include the graft copolymer in <NUM> part by weight to <NUM> parts by weight, <NUM> parts by weight to <NUM> parts by weight, or <NUM> parts by weight to <NUM> parts by weight based on <NUM> parts by weight of the vinyl chloride-based resin.

According to an embodiment of the present invention, the resin composition may include an additive such as an antioxidant, a thermal stabilizer, a plasticizer, a processing aid, a coloring agent, and a lubricant, well-known in the art in a typical amount, as necessary.

Hereinafter, embodiments of the present invention will be explained in detail so that a person skilled in the art could easily perform the present invention. However, the present invention may be accomplished in various other types and is not limited to the embodiments explained herein.

To a <NUM>, high-pressure polymerization reactor equipped with a stirrer, based on total <NUM> parts by weight of <NUM>,<NUM>-butadiene, <NUM> parts by weight of ion exchange water, <NUM> part by weight of sodium sulfate, <NUM> parts by weight of potassium oleate, <NUM> parts by weight of sodium ethylenediaminetetraacetate, <NUM> parts by weight of ferrous sulfate, <NUM> parts by weight of sodium formaldehyde sulfoxylate and <NUM> parts by weight of diisopropybenzene hydroperoxide were injected. Then, <NUM> parts by weight of <NUM>,<NUM>-butadiene and <NUM> parts by weight of mineral-based oil A (mineral oil:PDMS = <NUM>:<NUM> (weight ratio); viscosity range of mineral oil of <NUM> cs to <NUM>,<NUM> cs, viscosity range of PDMS of <NUM> cs to <NUM>,<NUM> cs) were injected in batch, and polymerization was performed at <NUM> for <NUM> hours to prepare a rubbery polymer latex. A final polymerization conversion ratio was <NUM>%, and the average particle diameter of rubbery polymer particles was <NUM>.

The polymerization conversion ratio was calculated as the ratio of the solid content of the rubbery polymer obtained with respect to the solid content of monomer injected.

To a closed polymerization reactor substituted with nitrogen, based on total <NUM> parts by weight of a rubbery polymer latex (based on the solid content), methyl methacrylate, ethyl acrylate, sodium methylallyl sulfonate and styrene, <NUM> parts by weight based on the solid content of the rubbery polymer latex prepared above was injected, <NUM> parts by weight of sodium ethylenediaminetetraacetate, <NUM> parts by weight of ferrous sulfate, and <NUM> parts by weight of sodium formaldehyde sulfoxylate were injected, <NUM> parts by weight of methyl methacrylate, <NUM> parts by weight of ethyl acrylate, <NUM> parts by weight of sodium methylallyl sulfonate, and <NUM> parts by weight of ion exchange water were injected in batch, and polymerization was performed at <NUM> for <NUM> hour. Then, <NUM> parts by weight of styrene and <NUM> parts by weight of ion exchange water were injected in an incre injection method, and polymerization was performed at <NUM> for <NUM> hour to prepare a graft copolymer latex. A final polymerization conversion ratio was <NUM>%, and the average particle diameter of graft copolymer particles was <NUM>.

The polymerization conversion ratio was calculated as the ratio of the solid content of the graft copolymer obtained with respect to the solid contents of the rubbery polymer and monomer injected.

To <NUM> parts by weight (based on the solid content) of the graft copolymer latex thus obtained, <NUM> parts by weight of a mixture of IR <NUM> antioxidant and dilauryl thiodipropionate (DLTDP) were injected, sulfuric acid and a sodium chloride aqueous solution were injected at <NUM> to agglomerate, the phases of a graft copolymer and water were separated at <NUM>, and then, dehydration and drying were conducted to obtain a graft copolymer dry powder.

The same method as in Example <NUM> was performed except for injecting mineral-based oil B (mineral oil:PDMS = <NUM>:<NUM> (weight ratio)) instead of the mineral-based oil A (mineral oil:PDMS = <NUM>:<NUM> (weight ratio)) in the same amount during preparing the rubbery polymer latex, in Example <NUM>.

The same method as in Example <NUM> was performed except for injecting <NUM> parts by weight of mineral-based oil B (mineral oil:PDMS = <NUM>:<NUM> (weight ratio)) instead of <NUM> parts by weight of the mineral-based oil A (mineral oil:PDMS = <NUM>:<NUM> (weight ratio)) during preparing the rubbery polymer latex, in Example <NUM>.

The same method as in Example <NUM> was performed except for injecting mineral-based oil B (mineral oil:PDMS = <NUM>:<NUM> (weight ratio)) instead of the mineral-based oil A (mineral oil:PDMS = <NUM>:<NUM> (weight ratio)) in the same amount during preparing the rubbery polymer latex, and injecting <NUM> parts by weight of ethyl acrylate instead of <NUM> parts by weight, and injecting <NUM> parts by weight of sodium methylallyl sulfonate instead of <NUM> parts by weight during preparing the graft copolymer latex, in Example <NUM>.

The same method as in Example <NUM> was performed except for not injecting the mineral-based oil A (mineral oil:PDMS = <NUM>:<NUM> (weight ratio)) during preparing the rubbery polymer latex, and injecting <NUM> parts by weight of ethyl acrylate instead of <NUM> parts by weight, and not injecting sodium methylallyl sulfonate during preparing the graft copolymer latex, in Example <NUM>.

The same method as in Example <NUM> was performed except for injecting mineral-based oil C (mineral oil:PDMS = <NUM>:<NUM> (weight ratio)) instead of the mineral-based oil A (mineral oil:PDMS = <NUM>:<NUM> (weight ratio)) in the same amount during preparing the rubbery polymer latex, in Example <NUM>.

The same method as in Example <NUM> was performed except for injecting polydimethylsiolxane (PDMS, viscosity range of <NUM> cs to <NUM>,<NUM> cs) instead of the mineral-based oil A (mineral oil:PDMS = <NUM>:<NUM> (weight ratio)) in the same amount during preparing the rubbery polymer latex, in Example <NUM>.

The same method as in Example <NUM> was performed except for injecting mineral-based oil B (mineral oil:PDMS = <NUM>:<NUM> (weight ratio)) instead of the mineral-based oil A (mineral oil:PDMS = <NUM>:<NUM> (weight ratio)) in the same amount during preparing the rubbery polymer latex, and injecting <NUM> parts by weight of ethyl acrylate instead of <NUM> parts by weight, and injecting <NUM> parts by weight of sodium methylallyl sulfonate instead of <NUM> parts by weight during preparing the graft copolymer latex, in Example <NUM>. In this case, when preparing a graft copolymer dry powder, phase separation of a graft copolymer and water was not generated on a latex phase in the graft copolymer latex prepared in Comparative Example <NUM> due to the increased amount of the sodium methylallyl sulfonate, and a dry powder was not prepared.

With respect to the graft copolymers prepared in Examples <NUM> to <NUM> and Comparative Examples <NUM> to <NUM>, the average particle diameters of rubbery polymer particles, and the weight average molecular weights of the graft layers of the graft copolymers were measured by methods below and are shown in Tables <NUM> and <NUM>.

In addition, the picture of the graft copolymer particles prepared in Example <NUM> was taken by transmission electron microscope (TEM) and shown in <FIG>. Referring to <FIG>, it could be confirmed that soft domains were formed in a rubbery polymer for the graft copolymer prepared in Example <NUM> of the present invention.

<NUM> parts by weight of a vinyl chloride resin (LG Chem, Ltd. , product name: <NUM>), <NUM> parts by weight of a thermal stabilizer (tin stearate), <NUM> part by weight of an internal lubricant (potassium stearate), <NUM> parts by weight of an external lubricant (paraffin wax), <NUM> parts by weight of a processing aid (LG Chem, Ltd. , product name: PA-<NUM>), and <NUM> parts by weight of a pigment were sufficiently mixed at a temperature of <NUM> using a high-speed stirrer, and cooled to prepare a vinyl chloride resin master batch. To the vinyl chloride resin master batch thus prepared, <NUM> parts by weight of each of the graft copolymer dry powders prepared in Examples <NUM> to <NUM> and Comparative Examples <NUM> to <NUM> were injected, and processed using a roll of <NUM> for <NUM> minutes to form a specimen having a thickness of <NUM>. Impact strength, whitening properties and processability (non-dispersion melting properties) were evaluated by methods below and are shown in Tables <NUM> and <NUM> below.

As shown in Tables <NUM> and <NUM> above, it could be confirmed that the resin composition including the graft copolymer prepared according to the present invention as an impact reinforcing agent, prevented the degradation of whitening properties or improved thereof, and showed excellent dispersibility and processability. Particularly, a soft domain was stably formed from the mineral-based oil in the rubbery polymer, and the weight average molecular weight of the graft layer of the graft copolymer could be increased due to the ionic bonds through sodium methylallyl sulfonate during preparing the graft copolymer, and accordingly, the entanglement between the vinyl chloride resin and the graft copolymer was reinforced, energy from external stress was reduced, and impact strength was improved.

On the contrary, in case of Comparative Example <NUM> in which the mineral-based oil was not injected during preparing the rubbery polymer, and the sodium methylallyl sulfonate was not injected during preparing the graft copolymer, it could be confirmed that processability was deteriorated, and impact strength was inferior.

In addition, in case of Comparative Example <NUM> in which the mineral-based oil was applied, but the PDMS content was high, and in case of Comparative Example <NUM> in which PDMS which is a silicone-based oil was applied instead of a mineral-based oil, it could be confirmed that whitening properties were extremely poor, and from this, it could be confirmed that a silicone-based oil such as PDMS induced whitening properties with respect to a vinyl chloride resin.

In addition, in case of Comparative Example <NUM> in which a mineral-based oil was applied, but its content was insufficient, it could be confirmed that a soft domain was insufficiently formed in the rubbery polymer, and impact strength was reduced. In case of Comparative Example <NUM> in which a mineral-based oil was applied, but its content was excessive, the absolute amount of PDMS was increased, and it could be confirmed that whitening properties were extremely poor as in Comparative Examples <NUM> and <NUM>.

In addition, in case of Comparative Example <NUM> in which sodium methylallyl sulfonate was applied but in an insufficient amount, the weight average molecular weight of the graft layer of a graft copolymer was insufficiently high, and it could be confirmed that the graft layer was insufficiently formed, and impact strength was reduced as well as processability. In case of Comparative Example <NUM> in which sodium methylallyl sulfonate was applied but in an excessive amount, the phase separation of the graft copolymer and water on a latex was not generated due to the increased amount of the sodium methylallyl sulfonate during preparing the graft copolymer dry powder, and a dry powder could not be prepared, and a specimen could not be formed, either.

Claim 1:
A graft copolymer comprising a rubbery polymer,
wherein the rubbery polymer comprises a conjugated diene-based monomer unit, and a soft domain,
the graft copolymer comprises an alkyl (meth)acrylate-based monomer unit, an aromatic vinyl-based monomer unit, and an alkali metal sulfonate-based monomer unit, wherein the graft copolymer comprises a graft layer comprising the alkyl (meth)acrylate-based monomer unit, the aromatic vinyl-based monomer unit and the alkali metal sulfonate-based monomer unit, which are grafted into the rubbery polymer,
the soft domain is formed by comprising a mineral-based oil,
the mineral-based oil comprises <NUM> wt% to <NUM> wt% of a mineral oil and <NUM> wt% to <NUM> wt% of a silicone-based oil,
the mineral-based oil is comprised in <NUM> parts by weight to <NUM> parts by weight based on <NUM> parts by weight of the rubbery polymer, and
the alkali metal sulfonate-based monomer unit is comprised in <NUM> wt% to <NUM> wt% based on the graft copolymer.