KR20010062870A - An impact-reinforcement agent for a transparent acryl typed resin - Google Patents

Abstract

PURPOSE: A method for preparing an impact modifier of a transparent acrylic resin is provided which provides the impact modifier having excellent transparency, weather-resistance, shock-resistance and processing property. CONSTITUTION: The method comprises steps of: (i) a first emulsion polymerization step which produces an emulsion of a glass phase polymer(an inside layer) particles having an average particle diameter of 100-180 nanometers by a process of: (a) after putting the mixture solution prepared by mixing ion exchange water, an acrylic monomer, an emulsifying agent, a crosslinking agent and graft under nitrogen air current, heating and stirring the solution; and (b) after adding a water-soluble initiator to the solution of the step (a) when the temperature of the solution reaches 60-90 deg.C, performing an emulsion-polymerization of the mixture; (ii) a second emulsion polymerization step which produces an emulsion, wherein a rubber phase polymer(a middle layer) is grafted on the glass phase polymer(the inside layer) and which has an average particle diameter of 200-300 nanometers, by a process of putting an acrylic monomer or a copolymer thereof, a water soluble initiator, an emulsifying agent, a crosslinking agent and a grafting agent in the emulsion of the step (i) with stirring it at 60-90 deg.C and then continuously performing an emulsion-polymerization of the mixture; and (iii) a third suspension polymerization step which produces an emulsion of the impact modifier of a transparent acrylic resin, wherein a glass phase polymer(an outside layer) is grafted on the rubber phase polymer(the middle layer) and which has an average particle diameter of 220-320 nanometers, by a process of putting an acrylic monomer, a polymerization controlling agent and a fat-soluble initiator in the emulsion of the step (ii) with stirring it at 20-60 deg.C, continuously performing a suspension-polymerization of the mixture.

Description

Manufacturing method of impact modifier for transparent acrylic resin {An impact-reinforcement agent for a transparent acryl typed resin}

According to the present invention, a shell layer, which is an outer layer of an impact modifier, is prepared by a suspension polymerization method using a fat-soluble initiator, thereby improving impact resistance and workability without significantly reducing the transparency and weatherability of the acrylic resin, and thus impacting a transparent acrylic resin having a three-layer structure. It relates to a new method for producing a reinforcing agent.

Conventionally, as a method of imparting impact resistance to an acrylic resin, a method of compounding an impact agent to an acrylic resin in a molding process or the like is widely used.

Conventionally, impact modifiers for transparent acrylic 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-based or ABS-based impact modifier, butadiene gas is used during manufacturing, and the manufacturing process is very cumbersome. Due to its low weatherability, physical properties are degraded when used outdoors for a long time, and the refractive index is different, which greatly 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 is a representative impact modifier to improve the weather resistance and impact strength while complementing these problems. The acrylate impact modifier is prepared by crosslinking and polymerizing vinyl monomers such as (meth) acrylic monomers, 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, such a 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 thickness is thick, a problem occurs that the impact strength is lowered.

On the other hand, Japanese Patent Application 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. Is lowered, and the mixing (mixability) with the matrix resin is worsened, resulting in processing difficulties.

In particular, when the outer layer (shell layer) of the impact modifier is emulsified in the presence of a water-soluble initiator, as described in the above-described conventional techniques, there are more components to be grafted into the intermediate layer, resulting in poor workability and residual impurities such as ionic impurities. Due to this, there is a problem that the color is poor and the physical properties are also reduced.

The present invention is to provide a method of manufacturing a three-layered structure of impact modifier for transparent acrylic resin excellent in impact resistance and workability without reducing the transparency and weather resistance while solving the problems of the prior art described above.

The present invention relates to a method for producing an impact agent for a transparent acrylic resin having a three-layer (outer layer-middle layer-inner layer) structure excellent in transparency, weather resistance, impact resistance and processability. More specifically, the present invention is characterized in that the inner and middle layers of the impact resistant agent are prepared by emulsion polymerization, and the outer layer is prepared by suspension polymerization.

Emulsion polymerization is a method in which a monomer, a surfactant, and a water-soluble initiator are used, and an initiator initiated in an aqueous solution is transferred to a monomer and polymerized. Suspension polymerization, on the other hand, is a monomer, a polymer stabilizer and a fat-soluble initiator are used, the initiator is a method in which the polymerization is carried out in the monomer mixed with the monomer.

The present invention is prepared by emulsion polymerization of the inner layer and the intermediate layer in order to easily control the particle size to obtain particles of the most impact resistance 200 ~ 300nm, the outer layer is more compatible with the matrix resin during processing than the particle size Because it is important, it is prepared by suspension polymerization. The outer layer prepared by the suspension polymerization can be prevented from changing the color of the product because the fat-soluble initiator is used as inert nitrogen gas instead of the water-soluble initiator that remains as impurities during the emulsion polymerization causing color discoloration.

Hereinafter, the present invention will be described in detail.

First, a cabinet layer of glass-like polymer is prepared by a step of emulsion polymerization. Specifically, after a solution containing ion exchanged water, an acrylic monomer, an emulsifier, a crosslinking agent, and a graft is added to a reactor under a nitrogen stream, the solution is heated and stirred, and when the temperature of the solution reaches 60 to 90 ° C., a water-soluble initiator. After the addition, emulsion polymerization was carried out to prepare an emulsion of glass-like polymer (inner layer) particles having an average particle diameter of 100 to 180 nm (conversion rate of 90 to 95%).

In this process, the average particle diameter of the glassy polymer (inner layer) depends on the acrylic monomer content and the amount of emulsifier used. Lowering the content of acrylic monomers to reduce the size of the glassy polymer is advantageous because it can form more rubbery polymer in the impact modifier. The amount of acrylic monomer used is about 5 to 40 parts by weight relative to the total monomers. In addition, it is preferable to adjust the average particle diameter of the glass-like polymer to 100 ~ 180nm by adjusting the amount of emulsifier.

It is preferable to use 0.2-4 weight part of emulsifiers, 0.1-15 weight part of crosslinking agents, and 0.1-15 weight part of graft agents with respect to 100 weight part of said acrylic monomers. In this step, it is preferable that the emulsion polymerization is carried out so that the ratio (conversion) of the acrylic monomer to the glass-like 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. The ion-exchanged water used in the above process is produced through the ion exchanger, and the one having a resistance value of 1 mega ohm or more under nitrogen stream is used. The ion-exchanged water is used 100 to 500 parts by weight relative to the total monomers.

Next, the intermediate | middle layer which is a rubbery polymer is manufactured by the process of two-step emulsion polymerization. Specifically, the emulsion-polymerized primary emulsion is stirred at 60-90 ° C., and an acrylic monomer or a copolymer thereof, a water-soluble initiator, an emulsifier, a crosslinking agent, and a graft agent are added thereto, followed by emulsion polymerization to continuously perform the emulsion polymerization. A rubbery polymer (intermediate layer) is grafted on the (inner layer) to prepare an emulsion of particles having an average particle diameter of 200 to 300 nm (conversion rate of 91 to 95%).

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 the above process, the weight of the rubbery polymer (intermediate layer) is preferably 40 to 90% by weight based on the total weight of the impact modifier monomer. In the above step, it is preferable that the acrylic monomer or its copolymer (hereinafter referred to as " second monomer ") is emulsion-polymerized so that the ratio (conversion rate) of conversion to the rubbery polymer is 91 to 95%. If the conversion is less than 91%, the thermal stability of the polymer is lowered, which may cause thermal decomposition during processing.

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

In the above process, it is preferable to use an acryl-based monomer capable of forming a rubber phase and a styrene-based, fluorine-based acryl-based or vinyl monomer having a high refractive index to control the refractive index.

Next, the outer layer, which is a glass polymer, is manufactured by a three step suspension polymerization process. More specifically, the emulsion-polymerized secondary emulsion was stirred at 20 to 60 ° C., and an acrylic monomer, a polymerization regulator, and a fat-soluble initiator were added thereto, followed by suspension polymerization at 70 to 90 ° C. to give the rubbery polymer (intermediate layer). A glass-like polymer (outer layer) is grafted onto to prepare an emulsion of an impact modifier for a transparent acrylic resin having an average particle diameter of 220 to 320 nm (at least 92% conversion).

In the above process, a solution in which the same acrylic monomer, the polymerization regulator and the fat-soluble initiator are mixed at a temperature of 20 to 60 ° C. is added at a time to polymerize while gradually raising the temperature to 70 to 90 ° C. At this time, if the temperature is raised too rapidly, the heat generation is severe, and the stability is lowered so that the aggregation and sedimentation should be noted. And the acrylic monomer is prepared to have a molecular weight similar to the matrix resin to improve the mixing with the matrix resin during processing.

In this case, an emulsifier, a crosslinking agent, and a graft agent are not used. Instead, a polymerization regulator and a fat-soluble initiator are used. The fat-soluble initiator is at least one compound selected from benzoyl peroxide, azobisisobutyronitrile and the like. It is preferable that a fat-soluble initiator content is 0.01-2 weight part with respect to 100 weight part of glass-like polymers (outer layer).

In general, when the conversion rate is less than 92% during the polymerization process, the thermal stability of the polymer is low, so that pyrolysis occurs during processing.

Acrylic monomers used in each step in the present invention is selected from an aromatic vinyl unit, acrylic acid or methacrylic acid alkyl ester monomer having 1 to 20 carbon atoms and acrylic acid or methacrylic acid fluoroalkyl ester monomer having 1 to 20 carbon atoms It is a species or more, the content of the monomer in the production of glass-like polymer (inner layer) of the total impact modifier composition is 5 to 40% by weight, the content of the monomer in the production of rubber-like polymer (intermediate layer) is 40 to 90% by weight, monomer in the manufacture of the outer layer The content of is preferably 10 to 40% by weight.

In the present invention, the emulsifiers (surfactants) are anionic emulsifiers such as sodium, ammonium or potassium salts of alkyl sulfates having 4 to 30 carbon atoms, in situ reactive emulsifiers or amphiphilic emulsifiers. Specifically, sodium dodecyl sulfate, sodium dioctylsulfosuccinate or sodium dodecylbenzene sulfate and the like are used. Emulsifier is used 0.2 to 4 parts by weight based on the total monomers.

Examples of the crosslinking agent include 1,2-ethanediol di (meth) acrylate, 1,3-propanedioldi (meth) acrylate, 1,4-butanedioldi (meth) acrylate and 1,5-pentanedioldi (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.

The graft agent uses allyl (meth) acrylate or diallyl maleate, and the amount of the graft agent is preferably 0.1 to 15 parts by weight based on the total monomers.

As the polymerization initiator, cumene hydroperoxide, potassium persulfate, sodium persulfate, ammonium persulfate, or azo water-soluble initiator is used. The amount of these used is preferably 10 parts by weight or less relative to the total monomers.

When the three-step suspension polymerization is completed, a three-part particle emulsion is obtained. The emulsion is slowly added dropwise to an excess of 0.1-2% magnesium sulfate or calcium chloride solution preheated to 50-100 ° C. to stir particles in the emulsion. The precipitated particles were washed three to four times with distilled water at about 70 ° C., and then dried in a vacuum oven at 80 ° C. for about 24 hours to prepare an impact modifier as a final product. Instead of using salt, it can also be dried with a spray dryer.

The impact modifier prepared as described above is an inner layer of [A] glass-like polymer, [B] an outer layer of rubber-like copolymer grafted to the inner layer, and [C] an outer layer of glass-like polymer grafted to the middle layer. It is a granular material of a three-layer structure having a.

The outer layer is prepared by a suspension polymerization method in the presence of a fat-soluble initiator, so that the graft component with the intermediate layer is small and there are few residual impurities. As a result, the impact modifier of the present invention does not degrade transparency and color change even when forming a thick plate acrylic resin. In addition, it is excellent in transparency and weather resistance, and also in impact resistance.

Various physical properties in the present invention are measured by the following method.

Transparency (%): ASTM D-1003 Method

Notched Izod Impact Strength (kg.cm/cm): ASTM D-256 Method

Yellow Index: ASTM D-1925 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

(Step 1) 54.1 kg of secondary distilled water was added to a 100-l reactor and heated to 80 ° C. under a nitrogen stream, followed by 3.77 kg of methyl methacrylate, 0.20 kg of ethyl acrylate, and 1,3-butanediol dimethacryl. 4.1683 kg of a mixed solution of rate 14.22 g, allyl methacrylate 1.58 g, and 22.5% sodium dioctylsulfosuccinate 182.5 g were added to the reactor, followed by stirring for 15 minutes. Thereafter, 30 g of 2.25% potassium persulfate solution was added thereto, followed by emulsion polymerization for 60 minutes (conversion rate 96%). At this time, the average particle diameter of the prepared glass-like polymer (inner layer) in the emulsion was 130 nm.

(Step 2) 177 g of 2.25% potassium persulfate solution was added to the glass polymer emulsion prepared in step 1, followed by stirring for 15 minutes, followed by 22.98 kg of butyl acrylate, 5.25 kg of styrene, and 499.95 g of 1,3-butanediol dimethacrylate. A mixed solution of 55.55 g of allyl methacrylate and 533.3 g of 21.8% sodium dioctylsulfosuccinate was added dropwise to the reactor at a rate of 350 g per minute. After completion of the dropwise addition, 177 g of 2.25% potassium persulfate solution was added. After 180 minutes of emulsion polymerization, 177 g of 2.25% potassium persulfate solution was added thereto. Then, emulsion polymerization was further performed for 180 minutes (conversion 95%). At this time, the average particle diameter of the prepared polymer (inner layer + middle layer) in the emulsion was 260 nm.

(Step 3) When the conversion rate was 93% or more, the mixture was stirred at 50 ° C for 10.92 kg of methyl methacrylate, 0.57 kg of ethyl acrylate, 22.98 g of dodecyl mercaptan and 2.25 g of azobisisobutyronitrile. Add to After the temperature was gradually raised to 80 ℃, the polymerization was carried out for 120 minutes to complete the suspension polymerization (conversion 95%). The average particle diameter of the polymer (improving agent) in the emulsion obtained after the polymerization was 283 nm, and the conversion rate was 95% based on the whole process.

The emulsion thus obtained is prepared by using a spray dryer to prepare the impact modifier, which is the final product in powder form, and then 2.5 kg of the impact modifier and 7.5 kg of the acrylic resin are mixed and extruded to prepare an impact specimen (thickness 4 mm). The results of evaluating various physical properties of the prepared impact specimen are shown in Table 1.

Example 2

An impact modifier and an impact sample were prepared in the same process and conditions as in Example 1 except that 11.49 kg of methyl methacrylate was used alone (no ethyl acrylate) as the monomer during the three-step suspension polymerization. The results of evaluating various physical properties of the prepared impact specimen are shown in Table 1.

Comparative Example 1

(Step 1) 54.1 kg of secondary distilled water was added to a 100-l reactor and heated to 80 ° C. under a nitrogen stream, followed by 3.77 kg of methyl methacrylate, 0.20 kg of ethyl acrylate, and 1,3-butanediol dimethacryl. 4.1683 kg of a mixed solution of rate 14.22 g, allyl methacrylate 1.58 g, and 22.5% sodium dioctylsulfosuccinate 182.5 g were added to the reactor, followed by stirring for 15 minutes. Then, 30 g of 2.25% potassium persulfate solution was added thereto, followed by emulsion polymerization for 60 minutes (conversion 95%). At this time, the average particle diameter of the prepared glass-like polymer (inner layer) in the emulsion was 130 nm.

(Step 2) The glassy polymer emulsion prepared in Step 1 is lowered to 50 ° C. 22.98kg butyl acrylate, 5.25kg styrene, 499.95g 1,3-butanedioldimethacrylate, 55.55g allyl methacrylate, 533.3g 21.8% sodium dioctylsulfosuccinate and azobisisobutyronitrile at a temperature of 50 ° C 11.95 g of mixed solution is added to the reactor. The temperature was gradually raised to 80 ° C. and then suspension polymerization was performed for 360 minutes (conversion rate 95%). At this time, the average particle diameter of the prepared polymer (inner layer + middle layer) in the emulsion was 420 nm.

(Step 3) When the conversion rate is 93% or more, the temperature is lowered to 50 ° C. At a temperature of 50 ° C., a mixed solution of 10.92 kg of methyl methacrylate, 0.57 kg of ethyl acrylate, 22.98 g of dodecyl mercaptan and 2.25 g of azobisisobutyronitrile is added to the reactor. After the temperature was gradually raised to 80 ° C., the polymerization was completed by performing suspension polymerization for 120 minutes (conversion 95%). The average particle diameter of the polymer (improving agent) in the emulsion obtained after polymerization was 460 nm, and the conversion rate was 95% based on the whole process.

The emulsion thus obtained is prepared by using a spray dryer to prepare the impact modifier, which is the final product in powder form, and then 2.5 kg of the impact modifier and 7.5 kg of the acrylic resin are mixed and extruded to prepare an impact specimen (thickness 4 mm). The results of evaluating various physical properties of the prepared impact specimen are shown in Table 1.

Comparative Example 2

(Step 1) 54.1 kg of secondary distilled water was added to a 100-l reactor and heated to 80 ° C. under a nitrogen stream, followed by 3.77 kg of methyl methacrylate, 0.20 kg of ethyl acrylate, and 1,3-butanediol dimethacryl. 4.1683 kg of a mixed solution of rate 14.22 g, allyl methacrylate 1.58 g, and 22.5% sodium dioctylsulfosuccinate 182.5 g were added to the reactor, followed by stirring for 15 minutes. Then, 30 g of 2.25% potassium persulfate solution was added thereto, followed by emulsion polymerization for 60 minutes (conversion 95%). At this time, the average particle diameter of the prepared glass-like polymer (inner layer) in the emulsion was 127 nm.

(Step 2) 177 g of 2.25% potassium persulfate solution was added to the glass polymer emulsion prepared in step 1, followed by stirring for 15 minutes, followed by 22.98 kg of butyl acrylate, 5.25 kg of styrene, and 4,99.95 g of 1,3-butanediol dimethacrylate. A mixed solution of 55.55 g of allyl methacrylate and 533.3 g of 21.8% sodium dioctylsulfosuccinate was added dropwise to the reactor at a rate of 350 g per minute. After completion of the dropwise addition, 177 g of 2.25% potassium sulfate solution was added. After 180 minutes of emulsion polymerization, 177 g of 2.25% potassium persulfate solution was added thereto. Then, emulsion polymerization was further performed for 180 minutes (conversion rate 96%). At this time, the average particle diameter of the prepared polymer in the emulsion (inner layer + middle layer) was 255 nm.

(Step 3) When the conversion was 93% or more, 100 g of 2.25% potassium persulfate solution was added to the reactor and stirred for 15 minutes. Emulsion polymerization was completed by adding 10.92 kg of methyl methacrylate, 0.57 kg of ethyl acrylate, 22.98 g of dodecyl mercaptan to the reactor at a rate of 150 g per minute, and then further polymerizing for 120 minutes (conversion 95%). The average particle diameter of the polymer in the emulsion (improving agent) obtained after polymerization was 274 nm, and the conversion rate was 95% based on the whole process.

The emulsion thus obtained is prepared by using a spray dryer to prepare the impact modifier, which is the final product in powder form, and then 2.5 kg of the impact modifier and 7.5 kg of the acrylic resin are mixed and extruded to prepare an impact specimen (thickness 4 mm). The results of evaluating various physical properties of the prepared impact specimen are shown in Table 1.

Property measurement result division Example 1 Example 2 Comparative Example 1 Comparative Example 2 Impact modifier particle size (nm) 283 285 460 274 Yellow index (%) 0.96 0.98 0.85 1.38 transparency(%) 92 92 86 92 Notched Izod Impact Strength (kgcm / cm) 3.6 3.5 2.8 3.4

In the present invention, since the outer layer of the impact modifier is prepared by a suspension polymerization method using a fat-soluble initiator, the components to be grafted on the intermediate layer are reduced, so that the impact modifier is excellent in processability and there is no residual impurities, so that the color of the product is also good. do.

In addition, the impact modifier prepared by the method of the present invention is excellent in transparency and weather resistance as well as excellent impact resistance.

Claims (3)

Method for producing an impact modifier for a transparent acrylic resin comprising an emulsion polymerization process for producing the inner layer and the intermediate layer and a suspension polymerization process for producing the outer layer as follows. -Below- (Iii) A mixture of ion-exchanged water, an acrylic monomer, an emulsifier, a crosslinking agent and a graft agent is added to a reactor under a nitrogen stream, and the solution is heated and stirred. When the temperature of the solution reaches 60 to 90 ° C., it is water-soluble. A one-step emulsion polymerization step of preparing an emulsion of glass-like polymer (inner layer) particles having an average particle diameter of 100 to 180 nm by adding an initiator, followed by emulsion polymerization; (Ii) While stirring the emulsion at 60-90 ° C, an acrylic monomer or a copolymer thereof, a water-soluble initiator, an emulsifier, a crosslinking agent and a graft agent are added thereto, followed by emulsion polymerization to continue the glass-like polymer (inner layer). A two-step emulsion polymerization process for preparing an emulsion of particles having a mean particle size of 200 to 300 nm (conversion rate of 91 to 95%) by grafting a rubbery polymer (intermediate layer) onto the phase, (Iii) While stirring the emulsion at 20-60 ° C, an acrylic monomer, a polymerization regulator, and a fat-soluble initiator are added thereto, followed by suspension polymerization at 70-90 ° C to give a glassy polymer (otherwise) Each step) is a three-step suspension polymerization process for producing an emulsion of impact modifier for transparent acrylic resin having an average particle size of 220 ~ 320nm (conversion rate of 92% or more). The method for producing an impact modifier for a transparent acrylic resin according to claim 1, wherein the fat-soluble initiator is benzoyl peroxide or azobisisobutyronitrile during the three-step suspension polymerization. The method according to claim 1, wherein the content of the fat-soluble initiator in the three-step suspension polymerization is 0.01 to 2 parts by weight based on 100 parts by weight of the glass polymer (outer layer).