KR100696081B1 - Impact modifier for transparent acrylic resin - Google Patents

Abstract

The present invention relates to an impact modifier for an acrylic resin, the innermost layer consisting of methyl methacrylate or methyl methacrylate copolymer; An intermediate layer made of butyl acrylate copolymer or butadiene copolymer; And it has a three-layer structure of the outermost layer consisting of methyl methacrylate or methyl methacrylate copolymer, wherein the molar ratio of methyl methacrylate of the innermost layer and the outermost layer is 1: 0.5 to 1:15, when the intermediate layer polymerization Manufactured with UV stabilizers and colorants, this can eliminate the hassle of adding additional additives when blending with acrylic resins by adding colorants and UV stabilizers during polymerization, and can produce equivalent effects in much smaller amounts. It can significantly improve impact resistance and optical properties.

3-layer structure, impact modifier for acrylic resin

Description

Impact modifier for transparent acrylic resin

The present invention relates to an impact modifier for a transparent acrylic resin, and more particularly to an impact modifier that can significantly improve impact resistance without lowering the basic physical properties and transparency of the acrylic resin.

In general, acrylic resins, that is, impact modifiers for polymethyl methacrylate, include methyl methacrylate-butadiene-styrene (hereinafter referred to as MBS), acrylonitrile-butadiene-styrene (hereinafter referred to as ABS) and acrylate-based. Etc. Among them, in the case of MBS or ABS, butadiene gas is used during manufacturing, the manufacturing process is very cumbersome, and the weather resistance is low, and the physical properties are degraded when used outdoors for a long time, and the refractive index is different, which significantly reduces the transparency. In addition, the ABS system has the disadvantage of using a larger amount of impact modifier in order to exhibit the same impact modifier.

As a representative impact modifier that improves weather resistance and impact strength while compensating for such deterioration of basic properties and complexity of the manufacturing process, an acrylate type may be mentioned. Since the acrylate impact modifier crosslinks and polymerizes a vinyl monomer such as methacryl monomer, styrene derivative and vinyl derivative, a surfactant, an initiator, a crosslinking agent and a graft agent, the impact applied from the outside is transferred from the matrix resin to the acrylic rubber layer. The energy is transmitted and absorbed again in the rubber layer to have an impact reinforcing effect, as well as to control the refractive index of the rubber layer, thereby having the advantage of being able to be processed without a significant decrease in transparency. However, when an external stress such as bending is applied to the molded article, the whitening phenomenon occurs around the external stress.

As a method for preventing such whitening and having an impact reinforcing effect, two to three steps emulsified in Japanese Patent Publication No. 55-148729, Japanese Patent Publication No. 46-31462, and Japanese Patent Publication No. 54-1584 A method of polymerizing a hard polymer having good core / shell structure by polymerization and good mixing property with a matrix resin in a final step has been proposed. In addition, Japanese Patent Publication No. 56-96862 discloses a method of polymerizing a graft copolymer having a high content of rubber components by highly crosslinking a rubbery polymer.

However, in the above method, when forming a hard polymer layer having good affinity with the matrix resin of the outer layer, when the thickness of the layer is too thick, the impact strength is lowered, and the amount of the rubber is less and the amount of the impact modifier is increased. In addition, in the case of highly crosslinked polymers, the elasticity of the rubber is lowered to reduce the shock absorption effect, and the processing becomes complicated and difficult.

In addition, when blending the impact modifier with a matrix resin, in order to improve weather resistance and optical properties (eg, haze, yellowing, transparency), an excessive amount of a colorant (organic or inorganic dye or pigment) and an ultraviolet stabilizer should be added. The haze, yellowness and transparency of the matrix resin are lowered.

Accordingly, the present inventors are studying the impact modifier that can prevent the degradation of weather resistance and optical properties of the resin by adding a separate colorant or ultraviolet stabilizer in a later process without changing the basic physical properties such as impact strength, the innermost layer As a result of properly adjusting the molar ratio of the monomer to the outermost layer and including the colorant and the UV stabilizer in the polymerization, it was found that the present invention satisfies these requirements, thereby completing the present invention.

Accordingly, an object of the present invention is to provide an impact modifier that can significantly improve impact resistance, weather resistance, and optical properties, and improve workability by not adding an additive during blending.

Impact reinforcing agent of the present invention for achieving the above object is the innermost layer consisting of methyl methacrylate or methyl methacrylate copolymer; An intermediate layer made of butyl acrylate copolymer or butadiene copolymer; And it has a three-layer structure of the outermost layer consisting of methyl methacrylate or methyl methacrylate copolymer, wherein the molar ratio of methyl methacrylate of the innermost layer and the outermost layer is 1: 0.5 to 1:15, when the intermediate layer polymerization It is characterized in that it is prepared by including a UV stabilizer and a colorant.

The present invention will be described in more detail as follows.

The innermost layer of the impact modifier of the present invention is composed of methyl methacrylate or methyl methacrylate copolymer, the middle layer is composed of butyl acrylate copolymer or butadiene copolymer, and the outermost layer is methyl methacrylate like the innermost layer. Consists of acrylate or methyl methacrylate copolymer, the present invention optimizes the molar ratio of methyl methacrylate used in the innermost and outermost layers and the amount of curing agent in each step.

In preparing the innermost layer and the outermost layer, the monomer is methyl methacrylate alone or a copolymer, and in the middle layer, one of butyl acrylate and butadiene selected from styrene, halogen or styrene derivative substituted with alkyl or aryl group having 1 to 20 carbon atoms Copolymerization with one or more selected monomers to maximize the impact reinforcement effect by optimizing the particle size of each step. In addition, the addition of UV stabilizers and colorants (organic or inorganic dyes or pigments) when polymerizing the intermediate layer, which causes yellowing and deterioration of weather resistance, not only solves the trouble of adding these additives in blending, but also in much smaller amounts. Equally effective, the optical properties and weatherability improvement compared to the existing product was realized.

The method of producing an impact modifier of the present invention comprises the first step of making a crosslinked glass phase having a glass transition temperature of 20 ° C. or higher; A second step of grafting a rubber phase having a glass transition temperature of 0 ° C. or less on the glass phase polymerized in the first step; And a third step of grafting a glass acryl homopolymer or copolymer having compatibility with an acrylic resin having a glass transition temperature of 20 ° C. or more on the phases formed in the first and second steps.

Specifically, in the first step, in order to control the size of the glass-phase emulsion, the cross-linking agent and the initiator are added while lowering the content of solids and controlling the amount of the surfactant to obtain a cross-linked glass phase.

In the second step, a small amount of comonomer is used as an acryl monomer capable of forming a rubber phase and an acryl or vinyl monomer substituted with a suitable styrene or halogen group having a high refractive index. Here, a crosslinked rubber phase is produced by adding a crosslinking agent and a surfactant and adding an initiator. In order to avoid agglomeration of rubber phases, monomer is slowly added dropwise and the reaction time is extended. In addition, by adding UV stabilizers and colorants (organic or inorganic dyes or pigments) during polymerization, it is possible not only to solve the hassle of adding these additives when blending, but also to exhibit an equivalent effect in a much smaller amount, compared to conventional products. To improve the characteristics and weather resistance.

In the third step, the same monomer as the matrix resin of the first step is used, and a surfactant and a crosslinking agent are not used to obtain an uncrosslinked polymer, thereby acting as a matrix by itself or mixing with the matrix resin when processing is required. Can be improved. In the third step, a chain transfer agent is used to control the molecular weight.

More specifically, the method of manufacturing the impact modifier of the present invention is as follows; Under nitrogen stream, ion-exchanged water, emulsifier, crosslinking agent and some monomers having a resistance value of 1 MΩ or more are added thereto, and polymerization is performed by adding an initiator when the internal temperature reaches 50 to 90 ° C. When the polymerization proceeds to form an emulsion, the remaining amount of one-stage monomer is slowly added dropwise and then polymerized. At the end of the polymerization further initiator is added to complete the one-step polymerization. The average particle diameter of the crosslinked glass polymer produced here is about 50 to 200 nm, preferably about 100 to 200 nm, and the size of the particles is controlled by adjusting the amount, type, and stirring speed of the surfactant. The particle size obtained is very uniform. The conversion rate in the first stage is high, 93-95%.

Then, the monomers of the second step and the crosslinking agent, the surfactant, the UV stabilizer, the pigment, etc. are mixed while maintaining the same temperature, and then slowly added dropwise to the solution to carry out the polymerization, and the initiator is polymerized at the end of the polymerization as in the first step. It is further added to complete the polymerization. The average thickness of the crosslinked rubbery polymer is 10 to 200 nm, preferably about 100 to 180 nm, and the size of the particles is very uniform. The conversion rate at this stage is also high, 93-99%.

In the third step, polymerization is carried out using a monomer and an initiator without adding a surfactant, and the initiator is added at the end of the second step, and the monomer is slowly added dropwise to the solution before polymerization. When the polymerization is almost finished, the initiator is finally added to complete the polymerization. The average thickness of the final glassy polymer is 10-200 nm, preferably about 20-80 nm, and the particle size is very uniform. The conversion rate at this stage is high, above 98%. The final particle size is also very uniform.

If the conversion rate is 90% or less in the above polymerization process, the thermal stability of the polymer is low and thermal decomposition occurs during processing. In order to improve thermal stability, only small amounts of surfactants and initiators are used as water-soluble water-soluble substances. In particular, when the rubber phase polymerization does not have sufficient dropping time and polymerization time or when a surfactant is not used, aggregation occurs.

On the other hand, the innermost layer and the middle layer is a cured state using a curing agent in 0.5 to 2.5 parts by weight relative to the monomer, the outermost layer is prepared by using a curing agent within 1.0 part by weight relative to the monomer as a grafted or cured state in the intermediate layer. At this time, the curing agent is 1,2-ethanediol dimethacrylate, 1,3-propanediol dimethacrylate, 1,4-butanediol dimethacrylate, 1,5-pentanediol dimethacrylate, 1,6 Hexanediol dimethacrylate, divinylbenzene, ethylene glycol dimethacrylate, propylene glycol dimethacrylate, butylene glycol dimethacrylate, triethylene glycol dimethacrylate, polyethylene glycol dimethacrylate, poly One selected from the group consisting of propylene glycol dimethacrylate, polybutylene glycol dimethacrylate and allyl methacrylate can be used.

Surfactants used for the polymerization are anionic, in situ reactive emulsifiers such as sodium, ammonium or potassium salts of alkyl sulfates having 4 to 30 carbon atoms, such as sodium dodecyl sulfate, sodium dioctylsulfosuccinate, sodium dodecylbenzene sulfate, and Amphiphilic emulsifier. The content is 0.1-4.0 weight part.

As the monomer, in the first step, the aromatic vinyl monomer, the methacrylic acid alkyl ester having 1 to 20 carbon atoms, the methacrylic acid alkylaryl ester having 1 to 20 carbon atoms, and the fluoroalkyl ester monomer having 1 to 20 carbon atoms are used. And at least one monomer selected from the group and the like, and the amount thereof is 5 to 20 parts by weight of the total monomers.

The monomer used in the second step is at least one monomer selected from butyl acrylate and butadiene, and is used in 10 to 70 parts by weight of the total monomers.

The monomer used in the third step is an aromatic vinyl monomer, a methacrylic acid alkyl ester having 1 to 20 carbon atoms, a methacrylic acid alkylaryl ester having 1 to 20 carbon atoms, or a fluoroalkyl ester monomer having 1 to 20 carbon atoms. It is used at 10-85 weight part of all monomers as 1 or more types of monomer chosen.

The crosslinking agent used in the present invention is 1,2-ethanedioldimethacrylate, 1,3-propanedioldimethacrylate, 1,4-butanedioldimethacrylate, 1,5-pentanedioldimethacrylate, 1,6-hexanediol dimethacrylate, divinylbenzene, ethylene glycol dimethacrylate, propylene glycol dimethacrylate, butylene glycol dimethacrylate, triethylene glycol dimethacrylate, polyethylene glycol dimethacrylate And at least one selected from the group consisting of latex, polypropylene glycol dimethacrylate, polybutylene glycol dimethacrylate, and allyl methacrylate, and the amount thereof is 0.1 to 15 parts by weight.

 In the present invention, the graft agent is at least one monomer having a double bond having different reactivity such as allyl methacrylate, diallyl maleate, α, β-unsaturated hydrocarbon, and the content thereof is 0.1 to 15 parts by weight.

Examples of the polymerization initiator include cumene hydroperoxide potassium persulfate, sodium sulfate, and azo water-soluble initiators, and the amount thereof is 0.02 to 2.0 parts by weight.

UV stabilizers include 2- (2'-hydroxy-5'-methylphenyl) benzotriazole, 2- (3'-t-butyl-2'-hydroxy-5'-methylphenyl) -5-chlorobenzotria Benzotriazole type compounds, such as a sol and 2- (3 ', 5'- di-t- butyl- 2'-hydroxyphenyl) -5-chlorobenzotriazole, The quantity is 0.005-1.0 weight with respect to a two-stage monomer. It is wealth.

The colorant used in the present invention is an organic or inorganic dye or pigment, at least one selected from inorganic pigments such as phthalocyanine and azo dyes or pigments, titanium dioxide, cadmium disulfide, etc. at 0.1 to 3.0 ppm with respect to the second stage monomer. use.

The ion-exchanged water used in the present invention is produced through an ion-exchange group, and is 80 to 800 parts by weight based on monomers as pure water having a resistance of 1 MΩ or more.

Thus, the impact modifier prepared alone or in combination with an acrylic resin can significantly improve the impact resistance and optical properties (haze, yellowing, transparency, etc.) compared to conventional products.

Hereinafter, the present invention will be described in detail with reference to Examples, but the present invention is not limited by the Examples.

Example 1

700 g of ion-exchanged water was added to a 3 L container, and the internal temperature was heated to 70 ° C. under a nitrogen stream, followed by 85 g of methyl methacrylate, 10 g of ethyl acrylate, 0.45 g of allyl methacrylate, and 0.78 g of sodium dioctyl persulfosuccinate. 20 g of the mixed solution was added to the reactor, followed by stirring for 15 minutes. Then, 8 ml of 1% potassium persulfate solution was added, followed by stirring for 60 minutes. When the polymerization was almost complete, the remaining mixed solution was added dropwise to the reactor at a rate of 5 g per minute. After completion of the dropwise addition, the reaction proceeded for 60 minutes.                     

13 ml of 1% potassium persulfate solution was added thereto, followed by stirring for 15 minutes, followed by 142 g of butyl acrylate, 20 g of styrene, 3.3 g of allyl methacrylate, and 1.65 × 10 ⁻⁴ g of violet B, tinuvin P, 2- ( A mixed solution of 0.033 g of 2'-hydroxy-5'-methylphenyl) benzotriazole and 1.3 g of sodium dioctylsulfosuccinate was added dropwise to the reactor at a rate of 8 g per minute. After completion of the dropwise addition, 13 ml of 1% potassium persulfate solution was added. After completion of the dropwise addition, the polymerization was further performed for 240 minutes, and 6 ml of 1% potassium persulfate solution was added to the reactor for further polymerization for 15 minutes. When the conversion rate was 93% or more, a mixed solution of 333 g of methyl methacrylate, 17.0 g of ethyl acrylate, and 7.0 g of dodecyl mercaptan (made by chaintransfer) was added dropwise to the reactor at a rate of 3 g per minute, followed by polymerization for 100 minutes. Completed. After completion of the polymerization, residual monomers were removed by vacuum.

The average particle diameter of the emulsion obtained after polymerization was 320 nm, and uniform particles with very low dispersion were obtained. Thus obtained emulsion was slowly added to 700 g of 1% magnesium sulfate or 1% calcium chloride solution preheated at 70 to 90 ° C., and stirred vigorously to obtain a fine powder solid. The powder was filtered off and washed with distilled water at 70 ° C. After repeating the same process 3 to 4 times and dried in a vacuum oven at 80 ℃ for 24 hours to obtain a final product.

In order to evaluate the impact reinforcing effect of the obtained impact modifier, 2,000 g of impact modifier, 500 g of polymethyl methacrylate resin, and 5 g of IRGANOX B 900 were added, mixed, and extruded to prepare a 4 mm Izod impact specimen and a sheet, which were impacted by ASTM D256. The strength was measured, and transparency, weather resistance, etc. were measured using the same specimens, and the results are shown in Table 2 below.

Example 2

The procedure for preparing the impact modifier was carried out in the same manner as in Example 1, except that 424 g of butyl acrylate was added without using styrene in the second step. The polymer was treated in the same manner as in Example 1, and the measurement results of the physical properties are shown in Table 2 below.

Example 3

The procedure for manufacturing the impact modifier was performed in the same manner as in Example 1, only 2g of Tinubin P was used in the second step, and 0.2 parts by weight of the amount of the curing agent used in the first and third steps, respectively, compared to the monomers. It was. The polymer was treated in the same manner as in Example 1, and the measurement results of the physical properties are shown in Table 2 below.

Comparative Example 1) Manufacturing Method of US Patent No. 3,793,462

An impact modifier powder was obtained according to the method disclosed in US Pat. No. 3,793,462. Calculate the physical properties of the powder by calculating the rubber component of the same amount as that contained in Example 1, mixing it with acrylic resin and extruding it according to the method of Example 1 to prepare a specimen, and the results are shown in Table 2 below. It was.

Comparative Example 2)

The procedure for preparing the impact modifier was performed in the same manner as in Example 1, and was prepared without using a colorant in the second step.                     

The polymer was treated in the same manner as in Example 1, and the measurement results of the physical properties are shown in Table 2 below.

Comparative Example 3)

The procedure for manufacturing the impact modifier was carried out in the same manner as in the above 1 and all processes, and did not use only a chain transfer agent and a curing agent.

The polymer was treated in the same manner as in Example 1, and the measurement results of the physical properties are shown in Table 2 below.

Impact reinforcement Example Comparative Example One 2 3 One 2 3 Methyl methacrylate molar ratio in the first and second steps 1: 3.92 1: 3.92 1: 3.92 3: 2 1: 3.92 1: 3.92 Hardener Usage Amounts for Monomers (parts by weight) Cabinet floor 0.47 0.47 0.2 0.6 0.47 0 Mezzanine 2.0 2.0 1.0 2.4 2.0 0 Outer layer 0 0 0.2 0 0 0 Layer thickness (nm) Cabinet floor 115 120 125 185 123 140 Mezzanine 130 140 170 80 141 200 Outer layer 21 23 16 45 30 28 Stage 2 Violet B Usage (× 10 ^-4 g) 1.65 1.65 1.65 0 0 1.65 Chain transfer agent addition amount (g) 0.6 0.6 0.6 0 0.8 0 Refractive index 1.491 1.483 1.491 1.490 1.487 1.488

Example Comparative Example How to measure One 2 3 One 2 3 Impact Strength (Notched Izod, kgcm / cm) 6.3 5.9 5.8 5.4 6.4 5.0 ASTM D-256 Flexural Strength (kg / ㎠) 900 750 760 910 920 780 ASTM D-790 Flexural modulus (kg / ㎠) 23,000 20,642 21,100 22,700 22,850 19,421 ASTM D-790 Light transmittance (%) 92 80 89 90 91 88 ASTM D-1003 color L 96 91 93 93 95 92 ASTM D-1003 a 0.2 0.8 0.4 0.8 0.6 0.8 b 1.0 2.4 2.0 1.8 1.6 2.1 Weather resistance Δb value 1.5 1.4 1.2 3.0 2.2 1.8 ASTM D-1003 Impact Strength (Notched Izod, kgcm.c) 6.1 5.8 5.6 5.0 6.0 4.6 ASTM D-256

From the results in Table 2, it can be seen that the acrylic resin containing the impact modifier according to the present invention has an impact strength equal to or greater than that of haze, yellowing, transparency, and the like.

As described in detail above, the impact modifier prepared by properly adjusting the molar ratio of the monomer forming the innermost layer and the intermediate layer according to the present invention and adding a colorant and an ultraviolet stabilizer to the intermediate layer is equivalent even if only a much smaller amount than the conventional one It can exert an effect, can improve impact resistance and optical properties, and can simplify the process because it does not need to add a separate additive to the resin composition during the post-process.

Claims (9)

Innermost layer consisting of methyl methacrylate or methyl methacrylate copolymer; An intermediate layer made of butyl acrylate copolymer or butadiene copolymer; And Has a three-layer structure of the outermost layer consisting of methyl methacrylate or methyl methacrylate copolymer, A molar ratio of methyl methacrylate of the innermost layer and the outermost layer is 1: 0.5 to 1:15, and the impact modifier for a transparent acrylic resin, characterized in that it was prepared including an ultraviolet stabilizer and a colorant in the middle layer polymerization. delete delete delete delete The innermost layer of particles is a spherical particle of 50 to 200nm, the thickness of the intermediate layer grafted to the innermost layer is 10 to 200nm, the thickness of the outermost layer is 10 to 200nm. Impact modifier for transparent acrylic resins. The method of claim 1, wherein the ultraviolet stabilizer is 2- (2'-hydroxy-5'-methylphenyl) benzotriazole, 2- (3'-t-butyl-2'-hydroxy'5'-methylphenyl) -5 Selected from -chlorobenzotriazole and 2- (3 ', 5'-di-t-butyl-2'-hydroxyphenyl) -5-chlorobenzotriazole, containing 0.005 to 1.0 parts by weight based on the intermediate monomer. Impact modifier for transparent acrylic resin characterized in that. The impact modifier of claim 1, wherein the colorant is selected from the group consisting of phthalocyanine or azo dyes or pigments, titanium dioxide and cadmium disulfide. An acrylic resin composition containing the impact modifier of claim 1.