KR19990042656A - Impact modifier for thermoplastic resin and method of manufacturing the same - Google Patents

Abstract

The present invention relates to an impact modifier for thermoplastic resins and a method for producing the same.

The present invention manufactures an acrylic impact modifier having a three-layer structure by the following three-step emulsion polymerization process.

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(i) emulsion polymerization (conversion rate 90-95%) in the presence of ion-exchanged water, emulsifier, crosslinking agent and polymerization initiator to prepare an emulsion of particles of glassy polymer (inner layer) having an average particle diameter of 150-250 nm. And (ii) adding a second monomer, an emulsifier and a crosslinking agent dropwise thereto, followed by emulsion polymerization, and adding a polymerization initiator in the polymerization completion step to form a rubbery polymer (intermediate layer) on the glass polymer (inner layer). To prepare an emulsion of particles having an average particle diameter of 200 to 300 nm (conversion rate of 91 to 95%),

(iii) a third monomer is added dropwise thereto, followed by emulsion polymerization, and a polymerization initiator is added in the polymerization completion step to graf the glassy polymer (outer layer) onto the rubbery polymer (intermediate layer), thereby obtaining an average particle diameter of 250 to An impact modifier of 350 nm is produced (92% or more conversion).

Description

Manufacturing method of impact modifier for thermoplastic resin

The present invention relates to a method for producing an impact modifier for thermoplastic resins.

Conventional impact modifiers for thermoplastic resins include methyl methacrylate-butadiene-styrene (hereinafter referred to as MBS), acrylonitrile-butadiene-styrene (hereinafter referred to as ABS), and acrylate impact modifiers.

Among them, in the case of the MBS or ABS impact modifier, butadiene gas is used during manufacturing, which makes the manufacturing process very cumbersome and reduces the transparency.

In addition, ABS-based impact modifiers have the disadvantage of using a larger amount of impact modifiers in order to exhibit the same impact reinforcement effect.

The acrylate-based impact modifier may be mentioned as a typical impact modifier to improve the weather resistance and impact strength while supplementing these problems. Acrylate crab impact modifiers are prepared by weighting (meth) acrylic monomers, vinyl monomers such as styrene derivatives and vinyl derivatives, surfactants, initiators, crosslinking agents and graft agents.

The acrylate-based impact modifier transfers the externally applied shock from the matrix resin to the acrylic rubber layer, and the energy is absorbed and diverged from the rubber layer, thereby providing an excellent impact reinforcing effect.

In addition, by designing the rubber layer well and the refractive index to match the matrix has the advantage that can be processed without degradation of transparency.

However, when an external stress such as bending is applied to the molded article, the whitening phenomenon occurs around the external stress.

In order to prevent such whitening phenomenon, Japanese Patent Publication Nos. 1980-148729, 1971-31462, and 1979-1584 disclose core-shell structure of the impact modifier by two to three stages of emulsion polymerization. In the final emulsion polymerization, a method of polymerizing a hard polymer having good mixing property with the matrix resin on the outer layer is proposed.

However, this method has a problem in that the amount of the rubber in the impact modifier is small, so that the amount of the impact modifier is increased, and when the outer layer is thick, the impact strength is lowered.

On the other hand, Japanese Patent Publication No. 1981-96862 proposes a method of using a graft copolymer having a high content of rubber components by highly crosslinking a rubbery polymer.

However, highly crosslinked polymers have a low elasticity of the rubber, thereby deteriorating the impact absorption effect and worsening the mixing property (mixability) with the matrix resin, resulting in processing difficulties.

The present invention provides a method for producing an impact modifier for a transparent acrylic resin that is easy to control the particle size, excellent mixing with the matrix resin, and a lot of rubber content to improve the impact resistance of the resin even when a small amount is used without deterioration of the basic physical properties. do.

The present invention relates to a method for producing an impact modifier for thermoplastic resins.

More specifically, the present invention relates to a method of manufacturing a three-layer impact modifier having an inner layer of a glass polymer, an intermediate layer of a rubber polymer, and an outer layer of a glass polymer through a three-step emulsion polymerization.

In addition, the present invention is to make the weight of the intermediate layer of the rubber-like polymer to 50% or more of the total weight to improve the impact resistance, and to reduce the thickness of the outer layer to 10% or less of the total thickness in order to shorten the mixing time with the matrix resin It is characterized in that the manufacturing.

In addition, the present invention is characterized in that the use of the emulsifier and the crosslinking agent in the emulsion polymerization process to form the outer layer to improve the compatibility with the matrix resin.

Hereinafter, the present invention will be described in detail.

First, the present invention manufactures an impact modifier for a transparent acrylic resin through a three-step emulsion polymerization process as follows.

(i) emulsion polymerization of a first monomer in the presence of ion-exchanged water, an emulsifier, a crosslinking agent and a polymerization initiator to prepare an emulsion of a glassy polymer; In the completion step, the polymerization initiator is added to prepare an emulsion of rubbery polymer particles grafted onto the glassy polymer,

(iii) The third monomer is added dropwise thereto, followed by emulsion polymerization, and a polymerization initiator is added in the emulsion polymerization completion step to prepare an impact modifier in which the glass polymer is grafted on the rubber polymer.

First, the process of emulsion-polymerizing a 1st monomer is demonstrated further more concretely.

A solution containing a mixture of ion-exchanged water, an emulsifier, a crosslinking agent, and a part of the first monomer is added to a reactor, and then heated and stirred. The solution is added to a polymerization initiator when the temperature reaches 60 to 90 ° C. to emulsify When the polymerization is carried out and the emulsion is formed, the polymerization is continued while dropwise addition of the remaining amount of the first monomer, and when the emulsion polymerization is completed, the polymerization initiator is added again to prepare an emulsion of the glass polymer (particle).

In this process, the average particle diameter of the glassy polymer (inner layer) is proportional to the amount of the first monomer and the amount of the emulsifier.

Lowering the content of the first monomer to reduce the size of the glassy polymer is advantageous because it can form more rubbery polymer in the impact modifier.

The amount of the first monomer is preferably about 5 to 30 parts by weight based on the total monomers.

In addition, it is preferable to adjust the average particle diameter of a glass-like polymer to 150-250 nm by adjusting the amount of an emulsifier.

In this step, it is preferable to perform emulsion polymerization so that the ratio (conversion) of the first monomer to the glass polymer is 90 to 95%.

If the conversion rate is less than 90%, the thermal stability of the polymer is lowered, causing pyrolysis during processing.

As the first monomer used in the above process, an aromatic vinyl-based unit, (meth) acrylic acid alkyl ester having 1 to 20 carbon atoms, alkyl methacrylate having 1 to 20 carbon atoms and (meth) acrylic acid having 1 to 20 carbon atoms At least one monomer selected from the group consisting of roalkyl esters is used.

Ion-exchanged water used in the above process is produced through an ion exchanger, and the metal ion concentration is 2 ppm or less.

The ion-exchanged water is used 100 to 500 parts by weight compared to the first monomer.

Next, the process of emulsion-polymerizing a 2nd monomer is demonstrated further more concretely.

While stirring the emulsion of the glass-like polymer (particle) at 60 to 90 ° C., the polymerization is continued while dropwise adding an emulsifier, a crosslinking agent and a second monomer, and a polymerization initiator is added again when the polymerization is completed.

By the said emulsion polymerization, a rubber-like polymer (intermediate layer) is grafted on a glass-like polymer (an inner layer).

The higher the content of the rubbery polymer (intermediate layer) in the impact modifier, the better the impact resistance.

In this process it is very important that the weight of the rubbery polymer (intermediate layer) is at least 50% of the total weight of the impact modifier.

If the weight of the rubbery polymer (intermediate layer) is less than 50% of the total weight of the impact modifier, the impact resistance deteriorates.

To this end, the amount of the second monomer is preferably 50 to 80 parts by weight based on the total monomers.

The average particle diameter of the particles (inner shell layer + middle layer) in which the rubbery polymer is grafted on the glassy polymer is set to 200 to 300 nm.

It is good to perform emulsion polymerization so that the ratio (conversion rate) by which a 1st monomer may be converted into a rubbery polymer in the said process may be 91 to 95%.

If the conversion is less than 91%, the thermal stability of the polymer is lowered, causing pyrolysis during processing.

In the above process, when the dropping time and the polymerization time of the second monomer are not sufficient or a surfactant is not used, a problem of agglomeration of monomers occurs.

In the process, at least one monomer selected from butyl acrylate and butadiene is used as the second monomer.

Next, the polymerization initiator and the third monomer are continuously added dropwise to the emulsion in which the two-stage emulsion polymerization is completed, and the polymerization initiator is added again at the time when the emulsion polymerization is completed, and the glass polymer on the rubbery polymer (intermediate layer) is added. An emulsion of the grafted particles of the (outer layer) is prepared.

The absence of emulsifiers and crosslinkers in this process is one of the important features of the present invention.

That is, since no emulsifier or crosslinking agent is used, no crosslinking is formed in the glassy polymer constituting the outer layer. As a result, the mixing with the matrix resin is improved.

In the above process, adjusting the thickness of the glass polymer (outer layer) grafted onto the rubber polymer to be 10% or less of the total thickness of the impact modifier shortens the mixing time with the matrix resin and reduces the rubber polymer content. It is advantageous to increase.

To this end, the amount of the third monomer is preferably 10 to 40% by weight based on the total monomers.

In the above process, the third monomer is an aromatic vinyl-based unit, (meth) acrylic acid alkyl ester having 1 to 20 carbon atoms, alkyl aryl ester having 1 to 20 carbon atoms, and fluoroalkyl having 1 to 20 carbon atoms At least one monomer selected from the group consisting of esters is used.

The average particle diameter of the impact modifier of the present invention prepared after the above step is preferably adjusted to be 250 ~ 350nm.

In the above step, it is preferable to perform emulsion polymerization so that the ratio (conversion) of the third monomer to the glass-like polymer is 92% or more.

If the conversion rate is low, the thermal stability of the polymer is lowered, so that pyrolysis occurs during processing.

In the present invention, the emulsifiers (surfactants) are sodium or potassium salts of alkyl sulfates having 4 to 30 carbon atoms. Specifically, sodium dodecyl sulfate, sodium dioctylsulfosuccinate or sodium dodecylbenzene sulfate and the like are used. In order to improve the thermal stability of the polymer, the emulsifier is preferably a water-soluble substance.

Emulsifier is used 0.2 to 4 parts by weight based on the total monomers.

As a crosslinking agent, 1, 2- ethanediol di (meth) acrylate, 1, 3- propanediol di (meth) acrylate, 1, 4- butanediol di (meth) acrylate, 1, 5- pentanediol di (meth) ) Acrylate, 1,6-hexanediol di (meth) acrylate, divinylbenzene, ethylene glycol di (meth) acrylate, propylene glycol di (meth) acrylate, butylene glycol di (meth) acrylate, tri Ethylene glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate, polypropylene glycol di (meth) acrylate, polybutylene glycol di (meth) acrylate, allyl (meth) acrylate, and the like are used.

The amount of these used is preferably 0.1 to 15 parts by weight based on the total monomers.

As the polymerization initiator, cumene hydroperoxide, potassium persulfate or sodium persulfate azo water-soluble initiator, or the like is used. Their amount is preferably 0.02 to 2.0 parts by weight based on the total monomers.

When the polymerization is completed, an emulsion of three-layered particles (average particle size: 250-350 nm) is obtained.

The emulsion is slowly added dropwise to a 1% -magnesium sulfate or 1% -calcium chloride solution preheated to 70-90 ° C. to stir particles in the emulsion. Instead of using salt, it can also be precipitated with a spray dryer.

The precipitated particles are washed three to four times with distilled water at about 70 ° C. and then dried in a vacuum oven at 60 ° C. for several days to prepare an impact modifier as a final product.

The impact modifier prepared as described above is an inner layer of [A] a glass polymer of a first monomer, an intermediate layer of [B] a rubbery polymer of a second monomer grafted to the inner layer, and [C] a graft of the intermediate layer. It is a granular material of the three-layer structure which has an outer layer which is the glass-like polymer of the 3rd monomer, The weight of the said intermediate | middle layer is 50% or more of the total weight, and the thickness of the outer layer is 10% or less of the total thickness.

The impact modifier of the present invention is excellent in impact resistance because the content of the rubbery polymer is high. In addition, since the thickness of the outer layer (glass polymer) is small, it is possible to increase the content of the rubber polymer, and there is no crosslinking in the outer layer resin, thereby shortening the mixing time with the mattress resin.

The present invention can easily adjust the average particle diameter of the impact modifier as the amount of use of the first monomer component and the emulsifier.

In the present invention, various physical properties are measured by the following method.

Impact strength (kg.cm/cm): ASTM D-256 method

Flexural Strength (㎏ / ㎠): ASTM D-790 Method

Flexural modulus (㎏ / ㎠): ASTM D-790 method

Hereinafter, the present invention will be described in detail with reference to Examples.

However, the following examples are provided to more easily understand the present invention, but the present invention is not limited to these examples.

Example 1

1000 g of secondary distilled water was added to a 3 L container, and the internal temperature was heated to 70 ° C. under a nitrogen stream, followed by mixing 20 g of methyl methacrylate 190 g ethyl acrylate, 0.9 g of allyl methacrylate, and 1.45 g of sodium dioctylsulfosuccinate. 40 g of solution was added to the reactor and stirred for 15 minutes.

Then, 15 ml of 1% potassium persulfate solution was added thereto, followed by stirring for 60 minutes. When the polymerization is almost complete, the remaining mixed solution is added dropwise to the reactor at a rate of 5 g per minute. After completion of the dropwise addition, the reaction was further conducted for 60 minutes to prepare an emulsion of a glass-like polymer (inner layer) having an average particle diameter of 180 nm. [Conversion rate 94%]

25 ml of 1% potassium persulfate solution was added thereto, followed by stirring for 15 minutes. A mixed solution of 284 g of butyl acrylate, 40 g of styrene, 6.5 g of allyl methacrylate, and 2.5 g of sodium dioctylsulfosuccinate was added at a rate of 8 g per minute. Dropwise to the reactor. After completion of the dropwise addition, 25 ml of 1% potassium persulfate solution is added. After completion of the dropwise addition, the mixture was further polymerized for 240 minutes, and then 12 ml of 1% potassium persulfate solution was added to the reactor and further polymerized for 15 minutes to obtain particles (average particle diameter 250 nm) grafted with a rubbery polymer (intermediate layer) on the inner layer. Prepare an emulsion. [Conversion rate 94%]

Here, a mixed solution of 86 g of methyl methacrylate and 4.5 g of ethyl acrylate was added dropwise to the reactor at a rate of 3 g per minute, followed by further polymerization for 100 minutes to complete the polymerization. An emulsion of grafted particles (average particle diameter 298 nm) is prepared.

The emulsion was added dropwise to a 1% magnesium sulfate solution preheated to 80 ° C. while stirring to prepare a powdered solid. The powder was washed three times with distilled water at 70 ° C. after filtration and dried in a vacuum oven at 60 ° C. for 2 days to prepare an impact modifier.

908g of the prepared impact modifier and 8g of Tinuvin-312 as additives, 4g of Irganox B-900 and 0.090g of Ubitex OB and 4,090g of acrylic resin, followed by extrusion molding 1/8 inch AZOD impact specimens were prepared and then evaluated for various physical properties.

Physical property evaluation results are shown in Table 1.

Example 2

In the two-step emulsion polymerization process of grafting a rubbery polymer (intermediate layer) on the inner layer layer, the impact modifier and the same as in Example 1, except that 324g of butyl acrylate is added without using styrene. Prepare the impact specimen.

The results of evaluating the various physical properties of the impact specimen are shown in Table 1.

Example 3

Impact modifiers and impact specimens were prepared in the same process and conditions as in Example 1 except that the impact modifiers present in the emulsion were precipitated with a spray dryer instead of salt.

The results of evaluating the various physical properties of the impact specimen are shown in Table 1.

Example 4

The impact modifiers and impact specimens were prepared in the same process and conditions as in Example 2 except that the impact modifiers present in the emulsion were precipitated with a spray dryer instead of salt.

The results of evaluating the physical properties of the impact specimens are shown in Table 1.

Example 5

The impact modifiers and impact specimens were prepared in the same process and conditions as in Example 1, except that tinubin-312, Iganox B900, and Unitex OB were not used in the preparation of the impact specimen.

The results of evaluating the various physical properties of the impact specimen are shown in Table 1.

Example 6

An impact modifier and an impact specimen were prepared in the same process and conditions as in Example 2 except that additives, such as tinuvin-312, Iganox B900, and Unitex OB, were not used.

The results of evaluating the various physical properties of the impact specimen are shown in Table 1.

TABLE 1

Physical property measurement result

The present invention can easily adjust the particle size of the impact modifier, and the rubber polymer (intermediate layer) content is high, so that the impact resistance of the resin can be improved without deteriorating basic properties.

In addition, the present invention can produce an impact modifier excellent in the mixing properties with the matrix resin by using an emulsifier and a cross-linking agent when producing a glass-like polymer constituting the outer layer of the impact modifier.

Claims (12)

Method for producing an impact modifier for thermoplastic resins, characterized in that it comprises essentially the following three-step emulsion polymerization process. -next- (i) emulsion polymerization (conversion rate 90-95%) in the presence of ion-exchanged water, emulsifier, crosslinking agent and polymerization initiator to prepare an emulsion of particles of glassy polymer (inner layer) having an average particle diameter of 150-250 nm. And (ii) adding a second monomer, an emulsifier and a crosslinking agent dropwise thereto, followed by emulsion polymerization, and adding a polymerization initiator in the polymerization completion step to form a rubbery polymer (intermediate layer) on the glass polymer (inner layer). To prepare an emulsion of particles having an average particle diameter of 200 to 300 nm (conversion rate of 91 to 95%), (iii) a third monomer is added dropwise thereto, followed by emulsion polymerization, and a polymerization initiator is added in the polymerization completion step to graf the glassy polymer (outer layer) onto the rubbery polymer (intermediate layer), thereby obtaining an average particle diameter of 250 to An impact modifier of 350 nm is produced (92% or more conversion). The method of manufacturing a thermoplastic impact modifier according to claim 1, wherein during the emulsion polymerization of the first monomer, a polymerization initiator is introduced in each of the steps in which the temperature of the polymerization solution reaches 60 to 90 ° C and the completion of the polymerization. The method of manufacturing a shock modifier for thermoplastic resins according to claim 1, wherein the amount of the polymerization initiator is adjusted so that the average particle diameter of the glass-like polymer is 150 to 250 nm when the glass-like polymer is prepared as the first monomer. The impact modifier for thermoplastic resin according to claim 1, wherein 5 to 30 parts by weight of the first monomer, 50 to 80 parts by weight of the second monomer, and 10 to 40 parts by weight of the third monomer are used based on 100 parts by weight of the total monomers. Method of preparation. The method of claim 1, wherein the first monomer and the third monomer are aromatic vinyl monomers, (meth) acrylic acid alkyl esters of 1 to 20 carbon atoms, (meth) acrylic acid alkylaryl esters of 1 to 20 carbon atoms, and (meth) of 1-20 carbon atoms. A method for producing a thermoplastic resin impact modifier, characterized in that at least one monomer selected from the group consisting of fluoroalkyl esters. The method for producing a shock modifier for thermoplastic resins according to claim 1, wherein the second monomer is at least one monomer selected from the group consisting of butyl acrylate and butadiene. The method of producing an impact modifier for thermoplastic resins according to claim 1, wherein the emulsifier is sodium or calcium salt of alkyl sulfate of 4 to 30 carbon atoms. The method for producing a shock modifier for thermoplastic resins according to claim 1, wherein the polymerization initiator is cumene hydroperoxide, potassium persulfate or sodium persulfate azo water-soluble initiator. [A] an inner layer of the glass polymer of the first monomer, [B] an intermediate layer of the rubber polymer of the second monomer grafted to the inner layer, and [C] a glass of the third monomer grafted to the intermediate layer A granular material having a three-layer structure having an outer layer which is a phase polymer, wherein the weight of the intermediate layer is 50% or more of the total weight, and the thickness of the outer layer is 10% or less of the total thickness. The impact modifier for thermoplastic resins according to claim 9, wherein the average particle diameter of the inner layer is 150 to 250 nm, and the average particle diameter of the entire impact modifier is 250 to 350 nm. The method of claim 9, wherein the first monomer and the third monomer are aromatic vinyl monomers, alkyl (meth) acrylates having 1 to 20 carbon atoms, alkyl aryl esters with 1 to 20 carbon atoms and (meth) acrylic acids having 1 to 20 carbon atoms. Shock absorbing agent for thermoplastic resins, which is at least one monomer selected from the group consisting of fluoroacrylic acid acrylates. The shock absorber for thermoplastic resin according to claim 9, wherein the second monomer is at least one monomer selected from the group consisting of butyl acrylate and butadiene.