KR20170037164A - Acrylic impact modifier, preparation method thereof, and polyvinyl chloride resin composition comprising the same - Google Patents

Abstract

The present invention relates to an acrylic impact reinforcing agent, to a preparation method thereof, and to a vinyl chloride resin composition comprising the same, and more specifically, to an acrylic impact reinforcing agent, which is obtained by firstly grafting an acrylic rubber core with surface-modified nano silica, and secondarily graft polymerizing the acrylic rubber core with a vinyl monomer; to a preparation method thereof; and to a vinyl chloride resin composition comprising the same, wherein the acrylic impact reinforcing agent facilitates manufacture of molded articles, having excellent impact resistance and surface quality, when used in a molding process of the vinyl chloride resin composition through surface modification.

Description

TECHNICAL FIELD The present invention relates to an acrylic impact modifier, a process for producing the same, and a vinyl chloride resin composition containing the acrylic impact modifier, a preparation method thereof, and a polyvinyl chloride resin composition,

The present invention relates to an acrylic impact modifier capable of producing a molded article having improved impact resistance and surface quality, a method for producing the same, and a vinyl chloride resin composition containing the same.

Impact reinforcing agents are mostly used in vinyl chloride resins typified by PVC. Vinyl chloride resins are used in various applications because of their low cost and easy processability. However, they are structurally resistant to shock and use impact modifiers.

The vinyl chloride impact modifier may be graft polymerized rubber such as MBS (MMA-Butadiene-Styrene), acrylic, ABS or the like; Thermoplastic polymer system of CPE, EVA; An inorganic impact modifier coated with calcium carbonate in stearin as an inorganic material, and the like.

Of these, MBS and acrylic are widely used. The MBS impact modifier is a copolymer obtained by grafting MMA and SM. The MBS impact modifier is used in hard and semi-rigid vinyl chloride resin products to improve impact strength and promote workability. The acrylic system is produced from BA, MMA and SM as raw materials.

However, such a composition alone can not attain a sufficient level of impact resistance. In recent years, a combination of an MBA and an acrylic impact modifier, an additional composition such as silicone rubber or silica, a modification of the core-shell structure or the use of a comonomer An impact modifier having a more complicated modification of the monomer system is proposed.

For example, Korean Patent Laid-Open Publication No. 2008-0049345 discloses an impact modifier composed of an acrylic rubber core and a PMMA shell mixed with a proper amount of silicone rubber as an impact modifier in order to increase the impact resistance of PC / PBT resin. However, the impact reinforcing agent proposed in this patent can not have a satisfactory level of impact resistance when applied to a vinyl chloride resin due to an increase in cost due to the use of silicone rubber and compatibility with acrylic rubber.

That is, the impact resistance is influenced by the content and particle size of the rubber latex. Increasing the rubber content and particle size to improve the impact strength is a very common method, but increasing the graft polymer content for the impact modifier mixed with the vinyl chloride resin leads to deterioration of the workability and, as a result, The transparency including the impact resistance, thermal stability and whitening resistance of the resin is reduced.

As an alternative, Korea Patent Registration No. 10-0837091 proposes a multi-layered acrylic impact modifier consisting of an acrylic seed / acrylic rubber core / MMA shell and suggests that when used, the impact resistance and weatherability of PVC resin can be further increased It is mentioned that inorganic substances such as silica, zeolite and calcium carbonate can be added to further increase impact resistance. However, protrusions occurred on the surface due to the added inorganic substances such as silica.

Korean Patent Publication No. 2008-0049345, "Thermoplastic resin composition and molded article using the same" Korean Patent Registration No. 10-0837091, "Acrylic rubber impact stiffener having improved impact resistance and weatherability and vinyl chloride resin containing the same"

The present inventors have conducted various studies to solve the above problems. As a result, they have found that an inner shell is formed by grafting an acrylic rubber core with surface modified nano silica in an impact modifier of a core-shell structure, It is possible to further improve the impact resistance and surface quality of the vinyl chloride resin composition due to the nano silica even when the content of the acrylic rubber core is small.

Accordingly, an object of the present invention is to provide an acrylic impact modifier in which an acrylic rubber core is sequentially grafted with a nano-silica and a vinyl-based monomer.

Another object of the present invention is to provide a method for producing the acrylic impact modifier.

It is still another object of the present invention to provide a vinyl chloride resin composition comprising the acrylic impact modifier and having improved impact resistance.

In order to achieve the above object, the present invention provides an acrylic impact modifier comprising a rubber core, an inner shell and an outer shell,

Wherein the rubber core comprises 70 to 85% by weight of an acrylic rubber core,

Wherein the inner shell is surface-modified nanosilica is grafted in an amount of 1 to 15% by weight,

Wherein the outer shell is graft-polymerized in an amount of 10 to 20% by weight of the vinyl-based monomer.

In addition,

Preparing an acrylic rubber core;

Grafting 1 to 15% by weight of the surface modified nanosilica to 70 to 85% by weight of the acrylic rubber core to form an inner shell;

And graft-polymerizing 10 to 20% by weight of the vinyl monomer to the obtained composite to form an outer shell.

The present invention also provides a vinyl chloride resin composition comprising the acrylic impact modifier.

The acrylic impact modifier according to the present invention can further improve the impact resistance of the vinyl chloride resin composition even when the content of the acrylic rubber core is reduced due to the inner shell of the surface modified nano silica between the core and the outer shell.

Further, no protrusion is generated on the surface, and the quality of the finally obtained vinyl chloride resin molded article can be improved.

Hereinafter, the present invention will be described in detail.

Acrylic impact Reinforcing agent

The present invention provides an acrylic impact modifier capable of improving the impact resistance of a vinyl chloride resin composition. The acrylic impact modifier comprises an acrylic rubber core, an inner shell and an outer shell.

The acrylic rubber core is prepared by copolymerizing 97 to 99.8% by weight of an alkyl acrylate and 0.2 to 3% by weight of a crosslinkable monomer.

The alkyl acrylate preferably has 1 to 8 carbon atoms in the alkyl group, and examples thereof include methyl acrylate, ethyl acrylate, propyl acrylate, isopropyl acrylate, butyl acrylate, hexyl acrylate, octyl acrylate, -Ethylhexyl acrylate, and combinations thereof, and preferably butyl acrylate is used.

The alkyl acrylate is preferably contained in an amount of 97 to 99.8% by weight based on 100% by weight of the total monomers forming the acrylic rubber core. When the content is less than the above range, there is a problem that the impact resistance is lowered due to the lowering of the rubber properties. On the other hand, when the content is in excess of the above range, the rubber property of the core is very high, so that the impact resistance is improved but the hardness and strength are lowered.

Also, the crosslinkable monomer may be at least one selected from the group consisting of divinylbenzene, 3-butanediol diacrylate, 1,3-butanediol dimethacrylate, 1,4-butanediol diacrylate, 1,4-butanediol dimethacrylate, It is possible to use one kind selected from the group consisting of allyl methacrylate, trimethylolpropane triacrylate, tetraethylene glycol diacrylate, tetraethylene glycol dimethacrylate, and combinations thereof, preferably using allyl methacrylate do.

The crosslinking monomer is preferably contained in an amount of 0.1 to 3% by weight based on 100% by weight of the total monomers forming the core. If the content is less than 0.1% by weight, the matrix and spherical particles may be deformed during processing. If the content is more than 3% by weight, the core exhibits a brittle characteristic and the impact reinforcing effect is deteriorated .

The acrylic rubber core comprising such a composition is contained in an amount of 70 to 85% by weight, preferably 75 to 80% by weight, in 100% by weight of the acrylic impact modifier. If the content is less than the above range, there may be a problem that the impact property is low due to a low rubber property to absorb the impact. On the contrary, when the content is above the range, the shell content is relatively decreased, As a result, the problem of processing may occur.

In particular, the acrylic impact modifier according to the present invention uses surface-modified nanosilica as an internal shell.

The nano silica is silica having an average particle diameter of not more than 1000 nm, preferably not more than 500 nm, more preferably not more than 1 nm and not more than 100 nm as the silica. The surface of the acrylic rubber core is homogeneously grafted and grafted so that the impact resistance Can be improved. If the size of the nanosilica particles is less than the above range, coagulation may occur when the internal shell is formed, and it is difficult to expect precipitation or improvement in impact resistance even if the size exceeds the above range. In addition, the particle size of the impact modifier obtained by the coagulation or precipitation becomes uneven, and when applied to a vinyl chloride resin, the surface quality of the finally obtained molded article is lowered.

At this time, the shape of the nanosilica is not particularly limited in the present invention, but a spherical shape is used.

The nanosilica has a large number of OH on its surface, and exhibits hydrophilicity. However, since the size of the nanosilica is very small, aggregation of nanosilica occurs, and it is difficult to form a shell uniformly surrounding the core. Therefore, in the present invention, the surface of the nanosilica is modified with a specific functional group, a hydrophobic group thereof, preferably a silane coupling agent, thereby facilitating the formation of the inner shell, thereby securing the desired improvement in impact resistance.

As the silane coupling agent, any of those having OH in the molecular structure can be used, and there is no particular limitation, and examples thereof include vinyltrimethoxysilane, vinyltriethoxysilane, vinyltripropoxysilane, Propoxysilane, vinyltributoxysilane, vinyltripentoxysilane, vinyltriphenoxysilane, vinyltriacetoxysilane, methacryloxysilane, methacryloxypropyltrimethoxysilane, methacryloxypropyltriethoxysilane , Methacryloyloxypropyltrimethylsilyloxysilane, vinyltris (2-methoxyethoxy) silane, tri (iso (meth) acryloxypropyl) Propoxy) vinylsilane, and combinations thereof. Preferably, methacryloxypropyltrimethoxysilane (MPS) is used.

The silane coupling agent reacts with the OH on the surface of the nanosilica in the molecular structure to modify the nanosilica. The modified nanosilica is then hydrophobic and is flexible due to the presence of the alkyl groups present in the molecular structure, effectively allowing the nanosilica to surround the core to form a uniform inner shell on the core surface.

The surface modification of the nanosilica using the silane coupling agent is not particularly limited in the present invention and can be carried out through a modification reaction of a known method.

The internal shell composed of such surface modified nano silica is contained in an amount of 1 to 15% by weight, preferably 5 to 10% by weight, in 100% by weight of the acrylic impact modifier. If the content is less than the above range, improvement in impact resistance can not be expected, and protrusions are generated on the surface to deteriorate the surface quality. On the contrary, if the content exceeds the above range, the impact strength is lowered. As appropriate.

The acrylic impact modifier of the present invention is graft-polymerized with the vinyl-based monomer after being grafted with the surface-modified nano-silica.

The vinyl monomer may be used alone as methyl methacrylate, which is excellent in compatibility with a vinyl chloride resin, or may be mixed with an alkyl (meth) acrylate as a comonomer if necessary. Methyl methacrylate, which constitutes the outer shell, has a high glass transition temperature and is highly compatible with vinyl chloride resins. When an impact modifier is used as an additive, the mechanical properties of the whole vinyl chloride resin molded article are enhanced by uniform dispersion In addition, the occurrence of protrusions on the surface is minimized to improve the surface quality of the finally obtained molded article.

The alkyl (meth) acrylate is not particularly limited in the present invention, and any of those conventionally used in this field can be used. Typically, the alkyl acrylate is selected from the group consisting of butyl acrylate, 2-ethylhexyl acrylate, methyl acrylate, ethyl acrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate, One selected paper is available. The alkyl (meth) acrylate is preferably used in an amount of not more than 5% by weight based on 100% by weight of total monomers forming the outer shell.

Using the above-described monomers, the outer shell of the present invention is contained in an amount of 10 to 20% by weight, preferably 12 to 17% by weight, in 100% by weight of the acrylic reinforcing agent.

If the content is less than the above range, the thickness of the outer shell is thin, so that the stability of the latex is lowered during the manufacturing process and cohesion occurs, so that the impact resistance can not be expected to be improved. On the contrary, when the thickness exceeds the above range, the thickness of the shell becomes thick, so that there is a possibility of coagulation during the manufacturing process, and the impact strength is rather lowered due to the decrease of the acrylic rubber core relatively.

The acrylic impact modifier according to the present invention as described above can be used in any method capable of forming a core-shell structure through grafting.

Specifically, the acryl-based impact modifier according to the present invention comprises

(S1) of producing an acrylic rubber core;

Grafting the surface-modified nanosilica to the acrylic rubber core to form an inner shell (S2);

And a step (S3) of forming an outer shell by graft-polymerizing the vinyl monomer to the obtained composite.

Each step will be described below.

First, an acrylic rubber core is prepared using the alkyl acrylate and the crosslinkable monomer as described above (S1).

The production of the acrylic rubber core is not particularly limited in the present invention, and may be polymerized by various methods such as emulsion polymerization, bulk polymerization, suspension polymerization, solution polymerization and the like, preferably emulsion polymerization.

Upon emulsion polymerization, the monomer may further contain an initiator, an emulsifier, and additives commonly known in the art such as a molecular weight regulator, an activator, a redox catalyst, and ionized water.

As the initiator, a water-soluble initiator can be used, and inorganic peroxides such as sodium persulfate, potassium persulfate, ammonium persulfate, potassium perphosphate, hydrogen peroxide and the like; butyl peroxide, t-butyl peroxide, cumene hydroperoxide, p-menthol hydroperoxide, di-t-butyl peroxide, t-butyl cumyl peroxide, acetyl peroxide, isobutyl peroxide, Organic peroxides such as an oxide, 3,5,5-trimethylhexanoloxide and t-butylperoxyisobutyrate; Nitrogen compounds such as azobisisobutyronitrile, azobis-2,4-dimethylvaleronitrile, azobiscyclohexanecarbonitrile, and azobisisobutyric acid (butyl acid) methyl. These initiators are used in an amount of 0.03 to 0.2 parts by weight based on 100 parts by weight of the total monomers.

The emulsifier may be selected from the group consisting of an anionic emulsifier, a cationic emulsifier and a nonionic emulsifier, and is not particularly limited in the present invention. Examples of the emulsifier include sulfonate, carboxylate, succinate, sulfosuccinate and metal salts thereof, such as alkylbenzenesulfonic acid, sodium alkylbenzenesulfonate, alkylsulfonic acid, sodium alkylsulfonate, sodium poly Anionic emulsifiers widely used in emulsion polymerization generally such as oxyethylene nonylphenyl ether sulfonate, sodium stearate, sodium dodecyl sulfate, sodium lauryl sulfate, sodium dodecyl sulfosuccinate, and abietic acid salt; A cationic emulsifier to which an amine halide, an alkylammonium salt, an alkylpyridinium salt or the like is bonded as a functional group of a higher aliphatic hydrocarbon; And nonionic emulsifiers such as polyvinyl alcohol and polyoxyethylene nonylphenyl. These emulsifiers are not limited to these emulsifiers. Such an emulsifier may be used in an amount of 0.1 part by weight to 5 parts by weight based on 100 parts by weight of the monomer mixture.

The molecular weight regulator is not particularly limited, and examples thereof include mercaptans such as a-methylstyrene dimer, t-octenyl mercaptan, n-dodecyl mercaptan and octyl mercaptan; Halogenated hydrocarbons such as carbon tetrachloride, methylene chloride, and methylene bromide; Containing sulfur compounds such as tetraethyldiaramisulfide, dipentamethylenediamisulfide, and diisopropylxanthogen disulfide, and may be used in an amount of 0.1 part by weight to 3 parts by weight based on 100 parts by weight of the monomer mixture.

Activators include, but are not limited to, at least one selected from the group consisting of sodium hydrogensulfate, sodium formaldehyde sulfoxylate, sodium ethylenediamine tetraacetate, ferrous sulfate, lactose, dextrose, sodium linolenate, May be added in the range of 0.01 to 0.15 parts by weight based on 100 parts by weight.

The redox catalyst may be, for example, sodium formaldehyde sulfoxylate, ferrous sulfate, disodium ethylenediamine tetraacetate, and cupric sulfate, and may be used in an amount of 0.01 to 0.1 parts by weight per 100 parts by weight of the monomer mixture. Parts by weight.

The polymerization can be carried out at 40 to 80 DEG C for 2 to 12 hours.

In the present invention, the monomer mixture may be added all at once to polymerize, or the monomer mixture may be separately added, and the mixture may be polymerized in stages. When the stepwise polymerization is carried out by dividing the monomer mixture, 60 to 90% by weight of the total monomer mixture is added in the first step and 10 to 40% by weight in the second step.

Next, the surface-modified nanosilica is grafted on the acrylic rubber core to form an inner shell (S2).

An emulsion polymerization method in which an initiator, an emulsifying agent and other additives are added for the grafting of this step is possible, and the conditions thereof are the same as those mentioned in S1 above.

For example, the acrylic rubber core, the surface modified nanosilica, the initiator, and the emulsifier are added to the reactor, and then the grafting is performed at 40 to 80 DEG C for 2 to 12 hours.

Next, an acryl-based impact modifier is prepared through a step (S3) of graft-polymerizing the vinyl monomer to the composite obtained in the step S2 and forming an outer shell.

An emulsion polymerization method in which an initiator, an emulsifier and other additives are added for the graft polymerization in this step is possible, and the conditions are the same as those mentioned in S1 above.

For example, after the addition of the complex, initiator, emulsifier and activator to the reactor, graft polymerization is carried out at 40 to 80 占 폚 for 2 to 12 hours.

Vinyl chloride resin  Composition

The acrylic impact modifier thus prepared is used as an additive in a vinyl chloride resin to improve the impact resistance and at the same time improve the surface gloss and moldability of the finally obtained molded article. Particularly, even if the rubber content of the acrylic rubber core is reduced by using the surface modified nano silica as the inner shell, the impact strength can be secured to a certain level or more.

Specifically, the vinyl chloride resin composition according to the present invention is added in an amount of 0.1 to 30 parts by weight as an acrylic impact modifier to 100 parts by weight of a vinyl chloride resin, and various molded articles are produced through various molding processes. The content of the acrylic impact modifier is intended to improve the impact resistance and surface condition of the finally obtained molded article. If the content of the acrylic impact modifier is less than the above range, improvement in impact resistance can not be expected. If the content exceeds the above range, Therefore, it is properly adjusted within the above range.

If necessary, various additives commonly used in this field may be further included. Examples of the additive include a processing aid, a heat stabilizer, a lubricant, a plasticizer, a UV stabilizer, a flame retardant, a colorant, a filler, a flame retardant, an antibacterial agent, a releasing agent, an antioxidant, a compatibilizing agent, a colorant, a surfactant, a nucleating agent, May be added, and they may be used alone or in admixture of two or more.

The foaming molding using the vinyl chloride resin composition is not particularly limited in the present invention, and the known method is followed.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the present invention. Such variations and modifications are intended to be within the scope of the appended claims.

[Example]

Example  1: Acrylic impact Reinforcing agent  Produce

The acrylic impact modifier was prepared through the steps (1) to (5) so as to have the same composition ranges shown in Table 1 below.

Configuration Furtherance content Acrylic rubber core BA / AMA (83.8 / 1.2 weight ratio) 75 wt% Inner shell Surface modified nano silica 10 wt% Outer shell MMA 15 wt%

(1) Production of acrylic rubber core

A four-necked flask equipped with a stirrer, a thermometer, a nitrogen inlet and a circulating condenser was charged with 80 parts by weight of deionized water (DDI water), 0.2 parts by weight of NaHCO ₃ , 0.01 part by weight of ferrous sulfate, 0.18 parts by weight of disodium ethylenediamine tetraacetate was charged and the temperature inside the reactor was maintained at 50 占 폚 under a nitrogen atmosphere.

Separately from the reactor, 50 parts by weight of ionized water, 0.60 part by weight of sodium lauryl sulfonate, 83.8 parts by weight of butylacrylate (BA), 100 parts by weight of Allylmethacrylate ; AMA) were added to prepare a monomer pre-emulsion.

When the internal temperature of the reactor reached 50 캜, a previously prepared monomer pre-emulsion was added for 5 hours, and 0.20 part by weight of an initiator t-butyl hydroperoxide (TBHP) and 0.20 part by weight of sodium formaldehyde sulfoxylate (SFS) The reaction was allowed to proceed at the same time. After 30 minutes of the monomer pre-emulsion addition, 0.01 part by weight of TBHP and 0.02 part by weight of SFS were added and aged for 1 hour.

(2) Surface modified nano silica production

In a 120 ml reactor, 4 g of nano silica (ludox LS-30, Grace) was stirred with toluene and ultrasonically dispersed.

Then, a solution prepared by dissolving 2 g of methacryloxypropyltrimethoxysilane (MPS) in 10 ml of ethanol was added, reacted at 50 ° C for 1 hour, and cooled to room temperature.

Then, the mixture was separated using a centrifuge, dried at 90 ° C under vacuum, extracted with toluene, and dried at 90 ° C for 24 hours to obtain a surface-modified nanosilica.

(3) Primary Grafting  step

A four-necked flask equipped with a stirrer, a thermometer, a nitrogen inlet and a circulating condenser was charged with 120 parts by weight of ionized water and 0.3 part by weight of SLS into the acrylic rubber core prepared in the above (1). MPS- For 20 minutes. To this was added 0.1 part by weight of initiator (TBHP), followed by reaction for 2 hours to perform primary grafting.

(4) Secondary Graft  Polymerization step

Before the reaction, 15 parts by weight of ion exchange water, 0.10 parts by weight of SLS and 14.4 parts by weight of methyl methacrylate (MMA) were added to prepare a monomer pre-emulsion.

0.07 part by weight of the complex obtained in (3), monomer pre-emulsion, initiator potassium persulfate and 0.03 part by weight of SFS as an activator were introduced at once to proceed the reaction.

After 30 minutes of the monomer pre-emulsion addition, 0.02 part by weight of potassium persulfate and 0.01 part by weight of SFS were added and aged for 60 minutes to perform secondary graft polymerization.

(5) Acrylic impact Reinforcing agent  Produce

100 parts by weight of the prepared latex graft copolymer was added with stirring while a CaCl ₂ aqueous solution (diluted solution of 20% by weight) was stirred to agglomerate the polymer particles to prepare an agglomerated slurry, Followed by dehydration and drying to obtain a graft copolymer powder.

Example  2: Acrylic impact Reinforcing agent  Produce

The acrylic impact modifier was prepared in the same manner as in Example 1, except that 80 wt% of the acrylic rubber core was grafted to 5 wt% of the surface modified nano silica.

Comparative Example  1: Acrylic impact Reinforcing agent  Produce

An acrylic impact modifier was prepared in the same manner as in Example 1, except that the surface modified nano silica was not used and that 75 wt% of the acrylic rubber core was graft polymerized to 25 wt% of methyl methacrylate.

Comparative Example  2: Acrylic impact Reinforcing agent  Produce

The acrylic impact modifier was prepared in the same manner as in Example 1 except that graft polymerization was carried out at 70% by weight of the acrylic rubber core with 15% by weight of surface-modified nano-silica and 15% by weight of methyl methacrylate.

Comparative Example  3: Acrylic impact Reinforcing agent  Produce

The acrylic impact modifier was prepared in the same manner as in Example 1, except that graft polymerization was carried out with respect to 80 wt% of the acrylic rubber core to 10 wt% of surface-modified nano-silica and 10 wt% of methyl methacrylate.

Comparative Example  4: Acrylic impact Reinforcing agent  Produce

The acrylic impact modifier was prepared in the same manner as in Example 1, except that graft polymerization was carried out at 80% by weight of the acrylic rubber core with 15% by weight of surface-modified nano-silica and 5% by weight of methyl methacrylate.

Comparative Example  5: Acrylic impact Reinforcing agent  Produce

The acrylic impact modifier was prepared in the same manner as in Example 1, except that graft polymerization was carried out with respect to 90 wt% of the acrylic rubber core to 5 wt% of the surface-modified nano-silica and 5 wt% of methyl methacrylate.

Experimental Example : Vinyl chloride series  Preparation of resin and measurement of physical properties

The acrylic impact modifier prepared in the above Examples and Comparative Examples was added to the composition of the vinyl chloride resin to measure physical properties, and the results are shown in Table 1 below.

(One) Vinyl chloride series  Manufacture of resin

100 parts by weight of a polyvinyl chloride resin (PVC; LS-100 manufactured by LG Chemical, degree of polymerization = 1000), 4.0 parts by weight of a heat stabilizer (DLP), 0.9 parts by weight of calcium stearate (Ca-St), 1.36 parts by weight of polyethylene wax , 1.0 part by weight of a processing aid (PA-821 manufactured by LG Chemical Co., Ltd.), CaCO ₃ And 4.0 parts by weight of TiO ₂ were put into a mixer at room temperature and then kneaded while raising the temperature to 115 ° C at 1000 rpm. When the temperature reached 115 캜, the temperature was lowered to 400 rpm and then cooled to 40 캜 to prepare a master batch.

6 parts by weight of an impact modifier was added to the masterbatch, and the mixture was milled at 190 DEG C for 7 minutes using a two-roll mill to prepare a 0.6-mm-thick sheet.

This sheet was cut into a size of 150 x 200 mm and then laminated in a mold of 3 x 170 x 220 mm with constant milling direction and preheated for 8 minutes using a hot press at 190 캜 ), Compression for 4 minutes (pressure 10 Kgf) and cooling for 3 minutes (pressure 10 Kgf) to prepare a vinyl chloride resin sheet having a thickness of 3 mm.

(2) Measurement of physical properties

Izod (kJ / m 2) Impact strength: The specimen was cut to a thickness of 3 mm and measured according to the ISO 180 standard method. The Izod impact strength of the impact-reinforcing vinyl chloride resin is preferably 10 or more.

- Projecting property: A vinyl chloride resin composition was prepared without adding a filler in the production of a vinyl chloride resin composition, and then a cylinder temperature of 180 ° C was measured using a 20-mm single screw extruder equipped with a T-die And a film thickness of 0.2 mm at a screw speed of 30 rpm. The number of protrusions existing in a predetermined region of the film surface was visually observed. When there was little protrusion, 5 points, when protrusions were slightly generated, 3 points, Was evaluated as 1 point.

- Elongation: The sample was prepared using ASTM D412 fixture and left for 24 hours at 23 ° C. Then, the sample was run at a speed of 10 mm / min using the INSTRON 4465 Model (ASTM D638).

IZOD impact strength (kJ / m 2) Protrusion characteristic (point) Elongation (%) Example 1 14 5 220 Example 2 13 4 215 Comparative Example 1 12 3 210 Comparative Example 2 12 5 220 Comparative Example 3 13 3 220 Comparative Example 4 12 3 220 Comparative Example 5 12 3 215

Referring to Table 2, when the acrylic impact modifier grafted with the surface modified nano silica is used according to the present invention, the impact strength and the elongation property are excellent, and protrusions are hardly formed.

In contrast, in the case of Comparative Example 1 in which graft polymerization was carried out directly on the acrylic rubber core with methyl methacrylate, the impact strength and elongation were largely lowered and the projection characteristics were lowered.

In addition, when the inner shell was formed of the surface-modified nano silica, the physical properties were different according to the content. In Comparative Example 2, the impact strength was decreased when the surface modified nano silica content was excessive. In Comparative Example 3 The protrusion is generated and the protrusion characteristic is degraded.

In addition, the change in physical properties according to the content of methyl methacrylate constituting the outer shell can be seen from the results of Comparative Example 4. Specifically, when graft polymerization of methyl methacrylate to 5% by weight is performed as in Comparative Example 4, the compatibility with the vinyl chloride resin is lowered, the protrusion characteristics are lowered, and the impact strength is also lowered.

Further, in Comparative Example 5, the acrylic rubber core was used in a high content in anticipation of improvement in impact resistance, and the impact strength was rather low, and the characteristics of the projection and the elongation were also deteriorated.

As a result of the above experimental example, the acrylic impact modifier according to the present invention is characterized in that when the content of the grafted material, that is, the surface nano silica and methyl methacrylate, is controlled, And elongation characteristics of the molded article can be improved and the occurrence of protrusions can be effectively prevented, thereby improving the surface quality of the molded article.

INDUSTRIAL APPLICABILITY The acrylic impact modifier of the present invention can be used as an impact modifier in the production of various molded articles using a vinyl chloride resin to make molded articles having excellent physical properties, particularly impact resistance and surface quality.

Claims (10)

An acrylic impact modifier comprising a rubber core, an inner shell and an outer shell,
Wherein the rubber core comprises 70 to 85% by weight of an acrylic rubber core,
Wherein the inner shell is surface-modified nanosilica is grafted in an amount of 1 to 15% by weight,
Wherein the outer shell is graft-polymerized in an amount of 10 to 20% by weight of the vinyl monomer. The method according to claim 1,
Wherein the acrylic rubber core is a copolymer of 97 to 99.8% by weight of an alkyl acrylate and 0.2 to 3% by weight of a crosslinkable monomer. 3. The method of claim 2,
Wherein the alkyl acrylate includes one selected from the group consisting of butyl acrylate, ethyl acrylate, propyl acrylate, 2-ethylhexyl acrylate, and combinations thereof. 3. The method of claim 2,
The crosslinkable monomer may be selected from the group consisting of divinylbenzene, 3-butanediol diacrylate, 1,3-butanediol dimethacrylate, 1,4-butanediol diacrylate, 1,4-butanediol dimethacrylate, allyl acrylate, Wherein the acrylic impact modifier is one selected from the group consisting of methacrylate, trimethylolpropane triacrylate, tetraethylene glycol diacrylate, tetraethylene glycol dimethacrylate, and combinations thereof. The method according to claim 1,
The surface-modified nanosilica is preferably a surface-modified nanosilica wherein the surface of the nanosilica is selected from the group consisting of vinyl trimethoxysilane, vinyl triethoxysilane, vinyltripropoxysilane, vinyltriisopropoxysilane, vinyltributoxysilane, vinyltripentoxysilane, vinyl Methacryloxypropyltrimethoxysilane, methacryloxypropyltriethoxysilane, N- (3-methacryloxyhydroxypropyl) -3-aminopropyltriethoxysilane, vinyltriethoxysilane, methacryloxysilane, methacryloxypropyltrimethoxysilane, (1) selected from the group consisting of propyltriethoxysilane, methacryloyloxypropyltrislimethylsilyloxysilane, vinyltris (2-methoxyethoxy) silane, tri (isopropoxy) vinylsilane, ≪ / RTI > wherein the acrylic impact modifier is modified with a compound of formula < RTI ID = 0.0 > The acrylic impact modifier according to claim 1, wherein the nanosilica is spherical particles having an average particle diameter of 1 to 1000 nm. The method according to claim 1,
Wherein the vinyl-based monomer is methyl methacrylate. 8. The method of claim 7,
Wherein said vinyl monomer is further copolymerized with an alkyl (meth) acrylate. Preparing an acrylic rubber core;
Grafting 1 to 15% by weight of the surface modified nanosilica to 70 to 85% by weight of the acrylic rubber core to form an inner shell;
And graft-polymerizing 10 to 20% by weight of the vinyl monomer to the obtained composite to form an outer shell. With respect to 100 parts by weight of the vinyl chloride resin,
A vinyl chloride resin composition comprising 0.1 to 30 parts by weight of the acrylic impact modifier of any one of claims 1 to 8.