Resin composition and preparation method thereof

Abstract

A resin composition according to one exemplary embodiment of the present invention contains: a graft copolymer containing a conjugated diene-based polymer, an aromatic vinyl monomer unit, and a vinyl cyano-based monomer unit; a matrix copolymer containing an aromatic vinyl monomer unit and a vinyl cyano-based monomer unit; and a crosslinked copolymer containing a crosslinking moiety formed of a crosslinking functional compound, an aromatic vinyl monomer unit, and a vinyl cyano-based monomer unit, in which the particle size (D50) of the crosslinked copolymer may be 30 [mu] m to 60 [mu] m in a case where the cumulative percentage on a particle size distribution map based on weight reaches 50%, and the particle size (D50) of the crosslinked copolymer may be 50 [mu] m to 60 [mu] m in a case where the cumulative percentage on the particle size distribution map based on weight reaches 50%. The average H-W ratio of the crosslinked copolymer may satisfy the following mathematical formula 1, and the light reflection variation coefficient calculated according to the following mathematical formula 2 may be 1.35 or less. [Mathematical formula 1] 0.09 < = average H-W ratio < = 1. In mathematical formula 1, the average H-W ratio is the average value of H-W ratios (a / b) calculated for each crosslinked copolymer observed when the surface of the resin composition is observed with an optical microscope. A is a value of 1 / 2 of the shortest axis length of each of the cross-linked copolymers observed in the case where the surface of the resin composition is observed with an optical microscope, and b is the longest axis length of each of the cross-linked copolymers observed in the case where the surface of the resin composition is observed with an optical microscope. [Mathematical formula 2] CLR = DL / ML, CLR being a coefficient of variation in light reflection, DL being a standard deviation of luminance, and ML being an average luminance.

Description

Technical Field

[0001] Cross-references to related applications

[0002] This application claims the benefit of Korean Patent Application No. 2023-0142384, filed on October 23, 2023, with the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference in its entirety. Technical Field

[0003] This invention relates to resin compositions and methods for their preparation. Background Technology

[0004] Acrylonitrile-butadiene-styrene (ABS) copolymers are prepared by graft copolymerization of styrene and acrylonitrile onto a butadiene rubber-like polymer. ABS copolymers offer a balanced combination of rigidity, chemical resistance, impact resistance, and processability, and possess excellent secondary processing properties such as impact strength, mechanical and physical properties, surface gloss, plating, printing, and painting. This is advantageous because products in a wide range of colors can be produced.

[0005] Furthermore, the demand for matte plastics has been increasing recently to enhance the premium appearance of products. To address this demand, methods are known for manufacturing sheets by co-extruding polymethyl methacrylate (PMMA) microparticles using ABS resin as a base layer, extruding sheets using reactive extrusion with a cross-linked polymer as a matting agent, or manufacturing sheets using crystalline polymers such as syndiotactic polystyrene (sPS) or polyamide (PA). However, when manufacturing using the above methods, problems arise such as a significant reduction in the mechanical and physical properties of the resin composition or a decrease in its processability.

[0006] Related technical documents

[0007] Patent documents

[0008] (Patent Document 1) JP 6571542 B2 Summary of the Invention

[0009] Technical issues

[0010] One object of the present invention is to provide a resin composition that has high mechanical and physical properties, a matte finish, and high surface uniformity.

[0011] Another object of the present invention is to provide a method for preparing a resin composition that has high mechanical and physical properties, a matte finish, and high surface uniformity.

[0012] Technical solution

[0013] (1) The present invention provides a resin composition comprising: a graft copolymer comprising a conjugated diene polymer, an aromatic vinyl monomer unit, and a vinyl cyano monomer unit; a matrix copolymer comprising an aromatic vinyl monomer unit and a vinyl cyano monomer unit; and a crosslinking copolymer comprising: a crosslinking portion formed by a crosslinking functional compound, an aromatic vinyl monomer unit, and a vinyl cyano monomer unit, wherein the particle size D of the crosslinking copolymer, based on a cumulative weight percentage of 50%, is... 50 The crosslinked copolymer has a wavelength of 30 μm to 60 μm, its average HW ratio satisfies the following mathematical formula 1, and its light reflectance variation coefficient calculated according to the following mathematical formula 2 is less than 1.35. [Mathematical Expression 1] 0.09 ≤ average HW ratio ≤ 1 In the above mathematical formula 1, The average HW ratio is the average of the HW ratios (a / b) calculated for each crosslinked copolymer, observed when the surface of the resin composition is viewed using an optical microscope. a is the value of half the shortest axis length of each crosslinked copolymer observed when the surface of the resin composition is viewed using an optical microscope, and b is the longest axis length of each crosslinked copolymer as observed when the surface of the resin composition is viewed using an optical microscope. [Mathematical Expression 2] C LR =D L / M L C LR It is the coefficient of variation of light reflection, D L It is the standard deviation of brightness, and M L That is the average brightness.

[0014] (2) The present invention provides a resin composition according to (1), wherein the particle size D50 of the crosslinked copolymer is 30 μm to 50 μm when the cumulative percentage based on weight reaches 50%.

[0015] (3) The present invention provides a resin composition according to (1), wherein the crosslinking functional compound forming the crosslinking portion of the crosslinked copolymer is an acrylate-based compound or an allyl compound.

[0016] (4) The present invention provides a resin composition according to (1), wherein the crosslinking functional compound forming the crosslinking portion of the crosslinked copolymer is allyl methacrylate.

[0017] (5) The present invention provides a resin composition according to (1), wherein the gloss level at 60° measured by a gloss meter according to the evaluation method of ASTM D523 is 7.5 or less.

[0018] (6) The present invention provides a resin composition according to (1), wherein, relative to a total of 100 parts by weight of the graft copolymer, the matrix copolymer and the crosslinking copolymer, the resin composition contains 10 to 35 parts by weight of the crosslinking copolymer and 48 to 63 parts by weight of the matrix copolymer.

[0019] (7) The present invention provides a method for preparing a resin composition, the method comprising: step S1: generating a crosslinked copolymer, wherein the particle size (D50) is 30 μm to 60 μm when the cumulative percentage based on weight on the particle size distribution map reaches 50%, and the average HW ratio satisfies the following mathematical formula 1; and step S2: mixing the crosslinked copolymer generated in step S1; a graft copolymer containing a conjugated diene polymer, an aromatic vinyl monomer unit and a vinyl cyano monomer unit; and a matrix copolymer containing an aromatic vinyl monomer unit and a vinyl cyano monomer unit, wherein step S1 comprises step S1-1 of initiating a polymerization reaction by loading an aromatic vinyl monomer, a vinyl cyano monomer and a polymerization initiator into a reactor, and step S1-2 of polymerizing by loading a crosslinking functional compound into the reactor in batches after step S1-1. [Mathematical Expression 1] 0.09 ≤ average HW ratio ≤ 1 In the above mathematical formula 1, The average HW ratio is the average of the HW ratios (a / b) calculated for each crosslinked copolymer, observed when the surface of the resin composition is viewed. a is the value of half the shortest axis length of each crosslinked copolymer observed when viewing the surface of the resin composition, and b is the longest axis length of each crosslinked copolymer as observed when the surface of the resin composition is viewed using an optical microscope.

[0020] (8) The present invention provides a method for preparing a resin composition according to (7), wherein step S1 further includes step S1-3 of pulverizing the product obtained in step S1-2.

[0021] Beneficial effects

[0022] The resin composition according to the present invention has excellent mechanical and physical properties and excellent surface uniformity, while also having a matte finish.

[0023] The production method according to the present invention provides a resin composition having excellent mechanical and physical properties, excellent surface uniformity, and matte finish. Detailed Implementation

[0024] The present invention will now be described in more detail to aid in understanding it.

[0025] The terms and words used in this specification and claims should not be interpreted restrictively in their ordinary or dictionary meaning, but should be interpreted in a way that best describes the principles of the inventor's invention and is consistent with the technical concept of the invention, based on the concepts that the inventor can appropriately define.

[0026] Unless otherwise defined, the terms and measurement methods used in this invention may be defined as follows.

[0027] The term "composition" as used in this invention includes a mixture of materials containing the materials of the composition as well as reaction products and decomposition products formed by the composition.

[0028] The terms “monomer unit,” “crosslinking unit,” or “crosslinking portion” used in this invention may refer to repeating units formed by compounds that act as monomers or crosslinking agents participating in polymerization or crosslinking reactions, structures derived therefrom, or the substances themselves.

[0029] The term "derivative" used in this invention can refer to a compound having a structure in which one or more hydrogen atoms constituting the original compound are replaced by halogen groups, alkyl groups or hydroxy groups.

[0030] <Resin Composition>

[0031] The present invention provides a resin composition.

[0032] The resin composition according to the invention comprises at least: a graft copolymer containing a conjugated diene polymer, aromatic vinyl monomer units, and vinyl cyano monomer units; a matrix copolymer containing aromatic vinyl monomer units and vinyl cyano monomer units; and a crosslinked copolymer containing a crosslinked portion, said crosslinked copolymer being formed from aromatic vinyl monomer units, vinyl cyano monomer units, and a crosslinking functional compound, wherein the particle size (D) of said crosslinked copolymer is such that, based on a cumulative weight percentage of 50%, it reaches 50% in a particle size distribution diagram. 50 The crosslinked copolymer has a crosslinking thickness of 50 μm to 60 μm, and its average HW ratio satisfies the following mathematical formula 1, and the light reflection variation coefficient calculated according to the following mathematical formula 2 is less than 1.35.

[0033] [Mathematical Expression 1]

[0034] 0.09 ≤ average HW ratio ≤ 1

[0035] In Formula 1, the average HW ratio is the average of the HW ratios (a / b) calculated for each crosslinked copolymer, observed under an optical microscope on the surface of the resin composition. a is the half-length of the shortest axis of each crosslinked copolymer observed when the surface of the resin composition is viewed under an optical microscope, and b is the longest axis length of each crosslinked copolymer observed when the surface of the resin composition is viewed using an optical microscope.

[0036] [Mathematical Expression 2]

[0037] C LR =D L / M L

[0038] In the above mathematical formula 2, C LR It is the coefficient of variation of light reflection, D L It is the standard deviation of brightness, and M L That is the average brightness.

[0039] Typically, surface treatment of the injection mold using etching to roughen its surface before resin injection allows existing matte products to have diffuse reflection properties on the surface. However, the problem with this method is that it is difficult to achieve a true matte finish, and the lack of processability due to mold wear makes it unsuitable for mass production.

[0040] On the other hand, there are molded products designed to achieve a matte finish through post-processing of low-gloss products. For example, there is a method of co-extruding a film containing cross-linked materials to adhere the film and thus form a pattern on the surface, or a method of applying cross-linked materials to a product and then curing it with UV to impart a pattern to the surface. However, in this case, there are limitations on the achievable gloss level and problems with poor surface uniformity.

[0041] Gloss level is a representative value that can indicate the gloss (high gloss level or low gloss level) or matteness of a resin. Typically, commercially available matte molded products have a gloss level greater than 30, which cannot be considered substantially matte. However, when using the resin composition according to the invention, very low gloss levels can be achieved, thus enabling matte products.

[0042] Furthermore, according to an exemplary embodiment of the invention, the resin composition has a low gloss level and a low coefficient of variation in light reflection, which enables the provision of matte molded products with a uniform surface, and the resin composition exhibits excellent mechanical and physical properties. These properties can be achieved by comprising an aromatic vinyl-vinyl cyano-acrylic acid crosslinked copolymer having a specific average particle size range, and such crosslinked copolymer allows for the resolution of problems associated with existing matte molded products.

[0043] In a resin composition according to an exemplary embodiment of the present invention, the gloss level at 60° as measured by a gloss meter according to the evaluation method of ASTM D523 may be 7.5 or less, and as a specific example, it may be 7.4 or less, 7.3 or less, 7.2 or less, 7.1 or less, or 7 or less.

[0044] In a resin composition according to an exemplary embodiment of the present invention, the isozo impact strength obtained by measuring a 1 / 4'' test piece according to the evaluation method of ASTM D256 can be 18 kg cm / cm or more, and as specific examples, it can be 18.2 kg cm / cm or more, 18.4 kg cm / cm or more, 18.6 kg cm / cm or more, 18.8 kg cm / cm or more, or 19 kg cm / cm or more.

[0045] In a resin composition according to an exemplary embodiment of the present invention, the flow index measured at 220°C and 10 kg according to the evaluation method of ASTM D1238 can be 10 g / 10 min or more, and as specific examples, it can be 10.2 g / 10 min or more, 10.4 g / 10 min or more, 10.6 g / 10 min or more, 10.8 g / 10 min or more, or 11 g / 10 min or more.

[0046] Each component contained in the resin composition will be described in detail below.

[0047] 1. Crosslinked copolymer

[0048] According to an exemplary embodiment of the invention, the crosslinked copolymer is a crosslinked copolymer that imparts surface properties such that light can diffusely reflect off the surface of the resin composition. The crosslinked copolymer is produced in a form with high strength due to crosslinking, thereby allowing it to have a uniform distribution within the matrix resin. When the resin composition includes the crosslinked copolymer, the impact strength can be improved to an excellent level, while achieving very low gloss levels and very low light reflection coefficients of variation.

[0049] According to an exemplary embodiment of the invention, a crosslinked copolymer may be included, such that its content is from 10 parts by weight to 35 parts by weight relative to 100 parts by weight of the resin composition. As a more specific example, it may be included, such that its content is 11 parts by weight or more, 12 parts by weight or more, 13 parts by weight or more, 14 parts by weight or more, or 15 parts by weight or more, and may also be included, such that its content is 34 parts by weight or less, 33 parts by weight or less, 32 parts by weight or less, 31 parts by weight or less, or 30 parts by weight or less. When the crosslinked copolymer is included within the above ranges, the impact strength can be improved to a superior level, while achieving a very low gloss level and a very low coefficient of variation of light reflection.

[0050] According to an exemplary embodiment of the present invention, the crosslinked copolymer may comprise a crosslinked portion formed by a crosslinking functional compound, an aromatic vinyl monomer unit, and a vinyl cyano monomer unit.

[0051] Crosslinked copolymers can be random copolymers, and the composition of aromatic vinyl monomer units and vinyl cyano monomer units in the copolymer can be homogeneous. The fact that the composition of the monomer units is homogeneous means that the ratio of each monomer unit present in the polymer, which is grown by polymerization and through the polymerization reaction of the monomers, remains uniform. As a concrete example, this might mean that as polymerization proceeds, i.e., depending on the polymerization time, the ratio of each monomer unit forming the polymer product remains uniform when a portion of the polymerization product is collected from the reactor.

[0052] According to an exemplary embodiment of the present invention, the aromatic vinyl monomer unit and the vinyl cyano monomer unit can each refer to a repeating unit formed by the polymerization reaction involving the aromatic vinyl monomer and the vinyl cyano monomer. As a specific example, the above-mentioned polymerization reaction can be a free radical polymerization reaction, and therefore, it can refer to a repeating unit derived from the carbon-carbon double bond present in the aromatic vinyl monomer and the vinyl cyano monomer.

[0053] According to an exemplary embodiment of the present invention, the crosslinked portion may contain crosslinked functional compound units formed by crosslinked functional compounds, which may contain one or more selected from acrylic compounds and allyl compounds.

[0054] According to an exemplary embodiment of the present invention, the crosslinked copolymer can make the crosslinked portions within the crosslinked copolymer very uniformly distributed, and the overall interchain fluidity can be maintained by making the distribution of the crosslinked portions appropriate.

[0055] According to an exemplary embodiment of the present invention, the crosslinking functional compound includes one or more selected from acrylic compounds and allyl compounds as described above, and may contain functional groups such as vinyl or acrylate groups. Specifically, one or more selected from divinylbenzene, trivinylbenzene, ethylene glycol di(meth)acrylate, allyl (meth)acrylate, diallyl phthalate, diallyl maleate, triallyl isocyanurate, and trialkyl isocyanurate may be used, and it may be divinylbenzene or allyl methacrylate.

[0056] According to an exemplary embodiment of the present invention, the crosslinked copolymer may contain a crosslinked portion such that its content is 0.05 parts by weight to 5 parts by weight relative to a total of 100 parts by weight of aromatic vinyl monomer units and vinyl cyano monomer units. As a more specific example, it may contain a crosslinked portion such that its content is 0.055 parts by weight or more, 0.06 parts by weight or more, 0.065 parts by weight or more, 0.07 parts by weight or more, 0.075 parts by weight or more, or 0.08 parts by weight or more, and it may also contain a crosslinked portion such that its content is 4.5 parts by weight or less, 4 parts by weight or less, 3.5 parts by weight or less, 3 parts by weight or less, 2.5 parts by weight or less, or 2 parts by weight or less. When the above ranges are satisfied, an appropriate level of crosslinking can be achieved.

[0057] According to an exemplary embodiment of the present invention, the aromatic vinyl monomer used to form the aromatic vinyl monomer unit contained in the crosslinked copolymer may be one or more selected from styrene, α-methylstyrene, α-ethylstyrene, p-methylstyrene, o-methylstyrene, o-tert-butylstyrene, bromostyrene, chlorostyrene, trichlorostyrene and its derivatives, and may specifically be styrene.

[0058] According to an exemplary embodiment of the present invention, the crosslinked copolymer may contain aromatic vinyl monomer units such that their content relative to a total of 100 parts by weight of aromatic vinyl monomer units and vinyl cyano monomer units is greater than 60 parts by weight and less than 85 parts by weight. As a more specific example, it may contain aromatic vinyl monomer units such that their content is 62 parts by weight or more, 64 parts by weight or more, 66 parts by weight or more, 68 parts by weight or more, 70 parts by weight or more, or 72 parts by weight or more, and it may also contain aromatic vinyl monomer units such that their content is less than 84 parts by weight, less than 83 parts by weight, less than 82 parts by weight, less than 81 parts by weight, less than 80 parts by weight, or less than 79 parts by weight.

[0059] According to an exemplary embodiment of the present invention, the vinyl cyano monomer used to form the vinyl cyano monomer unit contained in the crosslinked copolymer may be one or more selected from acrylonitrile, methacrylonitrile, ethylacrylonitrile and their derivatives, and as a specific example, it may be acrylonitrile.

[0060] According to an exemplary embodiment of the invention, the crosslinked copolymer may contain vinyl cyano monomer units such that their content relative to a total of 100 parts by weight of aromatic vinyl monomer units and vinyl cyano monomer units is greater than 15 parts by weight and less than 40 parts by weight. As a more specific example, it is more than 16 parts by weight, more than 17 parts by weight, more than 18 parts by weight, more than 19 parts by weight, more than 20 parts by weight, or more than 21 parts by weight, and it may also contain vinyl cyano monomer units such that their content is less than 38 parts by weight, less than 36 parts by weight, less than 34 parts by weight, less than 32 parts by weight, less than 30 parts by weight, or less than 28 parts by weight.

[0061] In a crosslinked copolymer according to an exemplary embodiment of the present invention, the particle size (D50) can be from 30 μm to 60 μm when the cumulative weight percentage on the particle size distribution map reaches 50%. In this invention, D50 refers to the particle size when the cumulative weight percentage on the particle size distribution map reaches 50%, and it refers to the particle size when the cumulative weight reaches 50% of the sample with the smallest particle size on the particle size distribution map. The D50 of the crosslinked copolymer in this invention can be measured using a laser diffraction measuring device, and as a specific example, it can be measured using an optical diffraction particle size analyzer (manufacturer: Sympatec GmbH, product name: HELOS / KR).

[0062] In a crosslinked copolymer according to an exemplary embodiment of the present invention, the particle size (D50) representing 50% by weight on the particle size distribution map can be 32 μm or more, 34 μm or more, 36 μm or more, 38 μm or more, or 40 μm or more. Alternatively, it can be 55 μm or less, 50 μm or less, 45 μm or less, or 40 μm or less. In the crosslinked copolymer, the D50 represents the particle size distribution. 50 When the above range is met, a low gloss level and excellent surface properties can be achieved in the resin composition. In the D of the crosslinked copolymer... 50 In cases exceeding the aforementioned range, when the crosslinked copolymer is dispersed in the matrix, the increased surface inhomogeneity caused by the crosslinked copolymer may reduce the surface properties and light reflectance variation coefficient of the resin composition. Furthermore, in the D... 50When the range is smaller than the above, the surface inhomogeneity of the crosslinked copolymer dispersed in the matrix decreases, which may increase the gloss level of the resin composition because diffuse reflection does not occur effectively.

[0063] In a crosslinked copolymer according to an exemplary embodiment of the present invention, the average HW ratio can be from 0.09 to 1. In the present invention, the average HW ratio of the crosslinked copolymer refers to the average value of the HW ratio (a / b) of each crosslinked copolymer observed when the surface of the resin composition is viewed using an optical microscope. a is half the shortest axis length of each crosslinked copolymer observed when the surface of the resin composition is viewed, and b is the longest axis length of each crosslinked copolymer observed when the surface of the resin composition is viewed.

[0064] Specifically, the aforementioned cross-linked copolymers can be observed in a plane within an optical microscope image. The plane in which the cross-linked copolymers are observed in an optical microscope image is called a "plane," and the density of the cross-linked copolymer is constant. Assuming that the center of gravity of the cross-linked copolymer lies only within the "plane," the longest axis of the cross-linked copolymer is the longest distance between two points where a straight line passing through the center of gravity intersects the surface of the plane, and the shortest axis of the cross-linked copolymer is the shortest distance between two points where a straight line passing through the center of gravity intersects the surface of the plane.

[0065] In a crosslinked copolymer according to an exemplary embodiment of the present invention, the average HW ratio may be 0.092 or more, 0.094 or more, 0.096 or more, 0.098 or more, or 0.1 or more. Alternatively, it may be 0.9 or less, 0.8 or less, 0.7 or less, 0.6 or less, 0.5 or less, 0.4 or less, or 0.3 or less. When the average HW ratio of the crosslinked copolymer satisfies the above-mentioned range, a low gloss level and excellent surface properties can be achieved in the resin composition.

[0066] According to an exemplary embodiment of the present invention, the gloss level of the resin composition is 7.5 or less, preferably 7 or less, more preferably 6.5 or less, and even more preferably 6 or less. When the resin composition does not contain crosslinking copolymers, the gloss of the resin composition may exceed the above range.

[0067] Furthermore, the resin composition according to an exemplary embodiment of the present invention enables the provision of molded products with guaranteed surface uniformity by comprising a crosslinked copolymer. The coefficient of variation of light reflection indicates the surface uniformity of the molded product, while also reflecting the gloss level, and it is a numerical value indicating whether equal degree of diffuse reflection occurs at any point on the surface of the molded product in a uniformly matte state throughout the surface.

[0068] The aforementioned coefficient of variation of light reflection can be measured using Python in the following method.

[0069] 1) Image capture of the sample: Using a DSLR camera (Canon 750D) and a 200mm×200mm surface light (white LED, collimated backlight LTS-3PFT), the image of the prepared sample was captured by setting the distance between the camera and the sample to 40cm, the distance between the sample and the light to 100cm, and the angle to 90°.

[0070] 2) Grayscale conversion of the sample image: The sample image is converted to grayscale (0 to 255) using the OpenCV library. In this case, a grayscale value is assigned to each pixel in the sample image, and this grayscale value is defined as the brightness.

[0071] 3) Image Reconstruction: The image was divided into a grid of 200μm × 200μm, and the brightness value (grayscale value) of the corresponding pixel in each grid was averaged to reconstruct the image. In this case, each grid has an average brightness value.

[0072] 4) Brightness Correction: The target grid is designated as the first region, the 8 grids adjacent to the first region are designated as the second region, and the 16 grids adjacent to the second region are designated as the third region. Then, as correction factors for each region, 1 is assigned to the first region, -0.0625 to the second region, and -0.03125 to the third region. The corrected brightness value of the target grid is then derived according to the following mathematical formula 3.

[0073] [Mathematical Expression 3]

[0074] In the above mathematical formula 2, L is the brightness of the target grid, L1 is the brightness of the grid in the first region, L21, L22, L23, ... and L28 are the brightness of the 8 grids in the second region, and L31, L32, L33, ..., L316 are the brightness of the 16 grids in the third region.

[0075] Considering the visual suppression effect, the aforementioned correction factor is used to readjust the brightness and minimize the error caused by optical illusions, which allow the brightness of the target grid to be measured to be evaluated differently due to the brightness of the surrounding grid when observed with the naked eye. Specifically, in the case of product commercialization, determining the so-called "matte" finish is more important in terms of human visual perception. Therefore, not only must the value measured by the device be indicated as matte, but it also needs to be actually perceived as matte visually. As a result, considering the phenomenon of optical illusions, this correction factor described above can be applied to the measured values ​​so that the measured values ​​derived from the device reach a level equivalent to the actual visual effect.

[0076] 5) Derivation of mean and standard deviation: Determine the mean and standard deviation based on the corrected brightness value of the corresponding grid, and use the mean and standard deviation of the brightness obtained in this way to derive the light reflection variation coefficient through the above mathematical formula 2.

[0077] According to an exemplary embodiment of the present invention, the coefficient of variation of light reflection of the resin composition may be 1.35 or less, and as a specific example, it may be 1.3 or less, 1.25 or less, or 1.2 or less. When the coefficient of variation of light reflection exceeds the above range, the quality of the surface appearance of the resin composition may deteriorate. When the coefficient of variation of light reflection exceeds the above range, the surface is non-uniform, which may mean that diffuse reflection does not occur at any part of the surface.

[0078] 2. Matrix copolymer

[0079] According to an exemplary embodiment of the present invention, the matrix copolymer is used as a matrix in the resin composition, and thus it can play a fundamental role in achieving the excellent physical properties of the resin molded product.

[0080] According to an exemplary embodiment of the present invention, the resin composition may comprise a matrix copolymer. The matrix copolymer may comprise aromatic vinyl monomer units and vinyl cyano monomer units.

[0081] According to an exemplary embodiment of the present invention, the aromatic vinyl monomer used to form the aromatic vinyl monomer unit contained in the matrix copolymer may be one or more selected from styrene, α-methylstyrene, α-ethylstyrene, p-methylstyrene, o-methylstyrene, o-tert-butylstyrene, bromostyrene, chlorostyrene, trichlorostyrene and its derivatives, and may specifically be styrene.

[0082] According to an exemplary embodiment of the present invention, the vinyl cyano monomer used to form the vinyl cyano monomer unit contained in the matrix copolymer may be one or more selected from acrylonitrile, methacrylonitrile, ethylacrylonitrile and their derivatives, and as a specific example, it may be acrylonitrile.

[0083] According to an exemplary embodiment of the present invention, the matrix copolymer may be included such that its content is 48 parts by weight to 63 parts by weight relative to 100 parts by weight of the resin composition. As a more specific example, the matrix copolymer may be included such that its content is 49 parts by weight or more, 50 parts by weight or more, 51 parts by weight or more, 52 parts by weight or more, or 53 parts by weight or more, and may also be included such that its content is 62 parts by weight or less, 61 parts by weight or less, 60 parts by weight or less, 59 parts by weight or less, or 58 parts by weight or less.

[0084] 3. Graft copolymers

[0085] According to an exemplary embodiment of the present invention, graft copolymers can be used to provide resin compositions with excellent moldability and impact resistance.

[0086] According to an exemplary embodiment of the present invention, the graft copolymer may comprise a conjugated diene polymer, an aromatic vinyl monomer unit, and a vinyl cyano monomer unit, and specifically, it may be a graft copolymer having a core-shell structure comprising a core containing a conjugated diene monomer unit and a shell surrounding the core and containing the aromatic vinyl monomer unit and the vinyl cyano monomer unit.

[0087] According to an exemplary embodiment of the present invention, the conjugated diene monomer used to form the conjugated diene monomer unit contained in the graft copolymer may be one or more selected from the group consisting of 1,3-butadiene, 2,3-dimethyl-1,3-butadiene, 2-ethyl-1,3-butadiene, 1,3-pentadiene and isoprene, and as a specific example, it may be 1,3-butadiene.

[0088] According to an exemplary embodiment of the present invention, the aromatic vinyl monomer used to form the aromatic vinyl monomer unit contained in the graft copolymer may be one or more selected from styrene, α-methylstyrene, α-ethylstyrene, p-methylstyrene, o-methylstyrene, o-tert-butylstyrene, bromostyrene, chlorostyrene, trichlorostyrene and its derivatives, and may specifically be styrene.

[0089] According to an exemplary embodiment of the present invention, the vinyl cyano monomer used to form the vinyl cyano monomer unit contained in the graft copolymer may be one or more selected from acrylonitrile, methacrylonitrile, ethylacrylonitrile and their derivatives, and as a specific example, it may be acrylonitrile.

[0090] According to an exemplary embodiment of the present invention, the graft copolymer may comprise a core containing conjugated diene units at a weight ratio of 30% to 70%; and a shell surrounding the core and containing aromatic vinyl monomer units and vinyl cyano monomer units at a weight ratio of 30% to 70%. Furthermore, the shell may comprise aromatic vinyl monomer units and vinyl cyano monomer units in a weight ratio of 7:3 to 8:2, and in this case, the copolymer may exhibit superior impact resistance, mechanical properties, and moldability.

[0091] According to an exemplary embodiment of the invention, a graft copolymer may be included, such that its content is from 12 parts by weight to 42 parts by weight relative to 100 parts by weight of the resin composition. As a more specific example, a graft polymer may be included, such that its content is 13 parts by weight or more, 14 parts by weight or more, 15 parts by weight or more, 16 parts by weight or more, or 17 parts by weight or more, and may also include a graft polymer, such that its content is 40 parts by weight or less, 38 parts by weight or less, 36 parts by weight or less, 34 parts by weight or less, or 32 parts by weight or less.

[0092] 4. Other additives

[0093] According to an exemplary embodiment of the present invention, the resin composition may further contain one or more additives selected from the group consisting of impact modifiers, slip additives, heat stabilizers, anti-drip agents, antioxidants, light stabilizers, UV shielding agents, pigments and inorganic fillers, and in this case, the additives may be used such that their content is less than 5.0 parts by weight, or 0.1 to 1.0 parts by weight, based on 100 parts by weight of copolymer and thermoplastic resin.

[0094] Furthermore, specific substances of additives may be used without particular limitation, as long as they are used in the thermoplastic resin composition. However, for example, in terms of additional flame retardancy improvement, for the aforementioned anti-dripping agents, one or more selected from the group consisting of Teflon, polyamide, polycrystalline silicon, PTFE (polytetrafluoroethylene), and TFE-HFP (tetrafluoroethylene-hexafluoropropylene) copolymers may be used, and for inorganic fillers, one or more selected from the group consisting of barium sulfate, barium glass filler, and barium oxide may be used.

[0095] <Methods for preparing resin compositions>

[0096] This invention provides a method for preparing a resin composition.

[0097] The method for preparing a resin composition according to the present invention comprises at least the step (S1) of preparing a crosslinked copolymer, wherein the crosslinked copolymer, having a cumulative weight percentage of 50% on a particle size distribution map, has a particle size (D) of... 50 The thickness is 30 μm to 60 μm, and the average HW ratio satisfies the following mathematical formula 1; and, The crosslinked copolymer produced in step S1; the graft copolymer containing conjugated diene polymer, aromatic vinyl monomer units and vinyl cyano monomer units; and the matrix copolymer containing aromatic vinyl monomer units and vinyl cyano monomer units are mixed in step (S2), wherein step S1 includes the step of initiating the polymerization reaction by loading the aromatic vinyl monomer, vinyl cyano monomer and polymerization initiator into the reactor (S1-1), and the step of polymerization after step S1-1 by batching the crosslinking functional compound into the reactor (S1-2).

[0098] [Mathematical Expression 1]

[0099] 0.09 ≤ average HW ratio ≤ 1

[0100] In the above mathematical formula 1, the average HW ratio is the average of the HW ratios (a / b) of each crosslinked copolymer observed under an optical microscope on the surface of the resin composition. a is half the shortest axis length of each crosslinked copolymer observed when the surface of the resin composition is viewed with an optical microscope, and b is the longest axis length of each crosslinked copolymer observed when the surface of the resin composition is viewed with an optical microscope.

[0101] In the following, a method for preparing a resin composition according to an exemplary embodiment of the present invention will be described step by step.

[0102] 1. Step in preparing the crosslinked copolymer (S1)

[0103] According to an exemplary embodiment of the present invention, step (S1) is the step of generating a crosslinked copolymer, wherein the particle size (D) reaches 50% by weight on the particle size distribution map. 50 The size of the polymer is 30 μm to 60 μm, and the average HW ratio satisfies mathematical formula 1. It may include the step of initiating the polymerization reaction by loading an aromatic vinyl monomer, a vinyl cyano monomer and a polymerization initiator into the reactor (S1-1), and the step of polymerization by loading a crosslinking agent including a crosslinking functional compound into the reactor after the above step (S1-1) (S1-2).

[0104] (1) Steps for initiating the polymerization reaction (S1-1)

[0105] According to an exemplary embodiment of the present invention, step (S1-1) is a polymerization initiation step, which allows the temperature of the reactor to be raised to a predetermined temperature after the reaction solution is loaded into the reactor. Even in step (S1) above, when the internal temperature of the reactor is raised above the predetermined temperature, the polymerization is carried out in the presence of a polymerization initiator, wherein the internal temperature of the reactor in step (S1) can be raised to about 60°C to 120°C, and preferably to 70°C to 110°C.

[0106] According to an exemplary embodiment of the present invention, in step (S1-1), aromatic vinyl monomers, vinyl cyano monomers and polymerization initiators can be loaded into the reactor.

[0107] According to an exemplary embodiment of the present invention, the aromatic vinyl monomer to be added in step (S1-1) may be one or more selected from styrene, α-methylstyrene, α-ethylstyrene, p-methylstyrene, o-methylstyrene, o-tert-butylstyrene, bromostyrene, chlorostyrene, trichlorostyrene and their derivatives, and may specifically be styrene.

[0108] Aromatic vinyl monomers can be added such that, relative to 100 parts by weight of vinyl cyano monomers and aromatic vinyl monomers added in step (S1-1), their content is 60 to 95 parts by weight, 64 to 90 parts by weight, 68 to 85 parts by weight, or 72 to 80 parts by weight. Within this range, the copolymer can be obtained with a high polymerization conversion rate, which can be a key point in achieving a matte finish while maintaining the mechanical and physical properties of the copolymer and providing excellent compatibility.

[0109] According to an exemplary embodiment of the present invention, the vinyl cyano monomer added in step (S1-1) may be one or more selected from acrylonitrile, methacrylonitrile, ethyl acrylonitrile and their derivatives. As a specific example, it may be acrylonitrile.

[0110] Furthermore, according to an exemplary embodiment of the invention, vinyl cyano monomers may be added such that, relative to 100 parts by weight of aromatic vinyl monomers and vinyl cyano monomers added in step (S1-1), their content is 5 to 40 parts by weight, 10 to 36 parts by weight, 15 to 32 parts by weight, or 20 to 28 parts by weight. Within this range, the copolymer can be obtained with a high polymerization conversion rate and provides excellent compatibility while maintaining the mechanophysical properties of the copolymer.

[0111] According to an exemplary embodiment of the present invention, the method for producing the above-mentioned crosslinked copolymer can be carried out by suspension polymerization, and the solvent used for polymerization in the above-mentioned (S1-1) step may further contain one or more additives selected from polymerization initiators, dispersants, dispersing aids and molecular weight control agents, wherein the method for producing the above-mentioned crosslinked copolymer can be carried out in the presence of these substances.

[0112] According to an exemplary embodiment of the present invention, a polymerization initiator is used to promote the initiation of polymerization, and there are no particular limitations, as long as it does not adversely affect the polymerization. However, it can be, for example, selected from one or more of the following: 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane, di(tert-butylperoxy-isopropyl)benzene, tert-butylcumyl peroxide, di(tert-pentyl)-peroxide, dicumyl peroxide, 4,4-di(tert-butylperoxy)valerate, tert-butyl perbenzoate, 2,2-di(tert-butylperoxy)butane, tert-pentyl perbenzoate, tert-butyl peracetate, tert-butyl peroxy(2-ethylhexyl) carbonate, tert-butyl peroxy isopropyl carbonate, tert-butyl peroxy-3,5,5-trimethylhexanoate, 1,1-di(tert-butylperoxy)cyclohexane, tert-pentyl peracetate, tert-pentyl peroxy-(2-ethylhexyl) carbonate, 1,1-di(t-tert-butylperoxy)- 3,5,5-Trimethylcyclohexane, 1,1-Di(tert-amylperoxy)cyclohexane, tert-butyl-monoperoxy-maleate, 1,1'-azobis(hexahydrobenzonitrile), 1,1'-azobis(cyclohexane-1-cyano), and azobisisobutyronitrile, and specifically, it may be selected from one or more of the following: dicumyl peroxide, 1,1-di(tert-butylperoxy)cyclohexane, 1,1'-azobis(cyclohexaneformitrile), and azobisisobutyronitrile.

[0113] Furthermore, the above-mentioned polymerization initiator can be used such that its content is 0.001 parts by weight to 0.5 parts by weight, specifically 0.003 parts by weight to 0.45 parts by weight or 0.06 parts by weight to 0.3 parts by weight, relative to 100 parts by weight of aromatic vinyl monomers and vinyl cyano monomers added in step (S1-1). When the polymerization initiator is used within the above range, it can promote the polymerization reaction and thereby increase the polymerization conversion rate.

[0114] According to an exemplary embodiment of the present invention, the dispersant may be selected from one or more of the following: water-soluble polyvinyl alcohol, partially saponified polyvinyl alcohol, polyacrylic acid, copolymer of vinyl acetate and maleic anhydride, hydroxypropyl methylcellulose, gelatin, calcium phosphate, tricalcium phosphate, hydroxyapatite, sorbitol monolaurate, sorbitol trioleate, polyoxyethylene, sodium lauryl sulfate, sodium dodecylbenzene sulfonate and sodium dioctyl sulfosuccinate, and as a specific example, it may be tricalcium phosphate.

[0115] According to an exemplary embodiment of the invention, a dispersant can be used such that its content is 1.0 to 3.0 parts by weight, 1.5 to 2.5 parts by weight, or 1.5 to 2.0 parts by weight relative to 100 parts by weight of aromatic vinyl monomers and vinyl cyano monomers charged in step (S1-1), and within this range, copolymers with more uniform particles can be produced while increasing the dispersion stability of the monomers in the polymerization system.

[0116] Furthermore, according to an exemplary embodiment of the present invention, the method for preparing the crosslinked copolymer can be carried out by further including a dispersing agent during polymerization. As a specific example, the dispersing agent can be a polyoxyethylene-based dispersing agent, and more specifically, it can be a polyoxyethylene alkyl ether phosphate, in which case excellent polymerization stability is provided.

[0117] According to an exemplary embodiment of the present invention, the molecular weight control agent may be, for example, selected from one or more of the following: α-methylstyrene dimer, tert-dodecyl mercaptan, n-dodecyl mercaptan and octyl mercaptan, carbon tetrachloride, dichloromethane, dibromomethane, tetraethylthiuram disulfide, dipentamethylenethiuram disulfide and diisopropyl xanthate disulfide, and as a specific example, it may be tert-dodecyl mercaptan.

[0118] According to an exemplary embodiment of the present invention, a molecular weight control agent added in step (S1-1) can be used such that, relative to 100 parts by weight of aromatic vinyl monomers and vinyl cyano monomers added in step (S1-1), the content of the control agent is 0.01 parts by weight to 0.40 parts by weight, 0.05 parts by weight to 0.30 parts by weight, or 0.10 to 0.25 parts by weight, and within this range, a copolymer having a suitable weight-average molecular weight can be produced.

[0119] (2) Polymerization step (S1-2)

[0120] According to an exemplary embodiment of the present invention, step (S1-2) is a step of adding a crosslinking agent containing the above-described crosslinking functional compound in batches, wherein the crosslinking agent may be added in two or more batches, or in three or more batches. Furthermore, the crosslinking functional compound includes one or more selected from acrylic compounds and allyl compounds as described above, and may contain functional groups such as vinyl or acrylic groups.

[0121] When polymerization is carried out by adding the crosslinking agent only in the initial stage of polymerization, the crosslinking effect can be relatively reduced. High concentrations of crosslinking agent in the initial stage of polymerization can increase the likelihood of side reactions where the crosslinking agents bond with each other. Furthermore, as polymerization progresses to later stages, the concentration of the crosslinking agent decreases, making it difficult for the crosslinked portions within the copolymer chains to distribute uniformly and hindering the formation of crosslinked copolymers. Therefore, the yield of crosslinked copolymers can be significantly reduced. These problems ultimately lead to increased gloss levels and light reflectance coefficients, and may even result in reduced impact strength due to a lack of uniformity.

[0122] According to an exemplary embodiment of the present invention, the crosslinking functional compound is added in step (S1-2), which can begin immediately after step (S1-1), and can be added in two or more parts during polymerization, and preferably in three or more parts during polymerization.

[0123] According to an exemplary embodiment of the present invention, the time difference between batch additions of the crosslinking functional compound in step (S1-2) can be 1% to 30% of the total polymerization time.

[0124] By setting a time difference between batch additions, a uniform and appropriate level of crosslinking can be achieved throughout the copolymer chain in the crosslinked copolymer, and the crosslinking density is also excellent. This can significantly contribute to providing diffuse reflection on the surface of the resin-molded product. Furthermore, the batch addition of the crosslinking agent can be carried out within 20% to 70% of the total polymerization time; however, it is preferable to start and end the batch addition within this time range to provide sufficient crosslinking effect.

[0125] According to an exemplary embodiment of the present invention, relative to the 100 parts by weight of aromatic vinyl monomers and vinyl cyano monomers added in step (S1-1), the crosslinking functional compound added in batches during polymerization step (S1-2) may be added in an amount of 0.05 parts by weight to 0.30 parts by weight, preferably 0.05 parts by weight to 0.20 parts by weight, and more preferably 0.05 parts by weight to 0.15 parts by weight.

[0126] In addition, according to an exemplary embodiment of the present invention, the amount of crosslinking functional compound added in each batch may be the same or different from each other, and it is preferable to control the deviation between the amounts of the added compounds to be small.

[0127] According to an exemplary embodiment of the present invention, in the above (S1-2) steps, the crosslinking agent may further include one or more of a molecular weight control agent and a polymerization initiator, which are then added separately.

[0128] In this way, when the molecular weight control agent and / or polymerization initiator are added batchwise along with the crosslinking functional compound in the above (S1-2) steps, the reactivity between monomers, the reactivity between polymer chains and crosslinking agents, etc., can be more easily controlled, thus facilitating the control of the degree of crosslinking. Therefore, the gloss level and coefficient of variation of light reflection are low, while impact strength and heat resistance are maintained at excellent levels, resulting in uniform and matte molded products.

[0129] On the other hand, according to an exemplary embodiment of the present invention, the polymerization in step (S1-2) can be carried out in a temperature range of 50°C to 150°C, and preferably in a temperature range of 60°C to 130°C, and more preferably in a temperature range of 65°C to 120°C. When polymerization is carried out within the above temperature range, it is desirable to obtain the final polymerization conversion rate and other polymer physical properties.

[0130] On the other hand, steps (S1-1) and (S1-2) according to an exemplary embodiment of the present invention can be carried out under stirring. When steps (S1-1) and (S1-2) according to an exemplary embodiment of the present invention are carried out under stirring at 800 rpm or higher, even without omitting the pulverizing step (S1-3) described later, the crosslinked copolymer to be produced can have a target particle size (D) of 50% on the particle size distribution map based on a cumulative percentage by weight. 50 It also has a target average HW ratio.

[0131] (3) Crushing step (S1-3)

[0132] According to an exemplary embodiment of the present invention, if step (S1-1) or step (S1-2) is carried out without stirring or with stirring at less than 800 rpm, step (S1) may further include step (S1-3): pulverizing the product obtained in step (S1-2). Step (S1-3) may be to achieve a target particle size (D) such that the crosslinked copolymer has a cumulative percentage by weight of 50% on the particle size distribution map. 50 The process of comparing the target average HW with the target average HW.

[0133] According to an exemplary embodiment of the present invention, steps (S1-3) can be performed using any one or more of an air jet mill, rotary mill, cutting mill, ball mill, or hammer mill.

[0134] 2. Step S2: Mixing crosslinked copolymers, matrix copolymers, and graft copolymers.

[0135] According to an exemplary embodiment of the present invention, in step (S2), the crosslinked copolymer, matrix copolymer and graft copolymer produced by the production method described above are mixed to produce a resin composition.

[0136] According to an exemplary embodiment of the present invention, commercially available resins can typically be applied to matrix copolymers, which can be obtained by commercial methods or by methods that do not use crosslinking agents in the above-described methods for preparing crosslinked copolymers.

[0137] According to an exemplary embodiment of the present invention, commercially available resins can typically be applied to graft copolymers, which can be obtained through commercial methods. For example, the graft copolymer described above can be produced by emulsion polymerization of conjugated diene monomers to generate a core (or seed) as a rubbery polymer, followed by the addition of vinyl cyano monomers and aromatic vinyl monomers to the core for emulsion graft polymerization.

[0138] <Molded Products>

[0139] This invention provides a molded product containing a resin composition. For example, the molded product described above can be applied to various industrial fields, such as various electrical and electronic products and vehicle parts. General molding methods such as extrusion, injection, or casting can be used as molding methods. Furthermore, for example, in injection molding, compared to products designed to provide a matte finish by subjecting the mold surface to etching treatment, the molded product according to the invention does not require etching treatment of the mold surface and can provide a molded product with a matte and uniform surface in the injection-molded state without even post-processing the molded product.

[0140] Embodiments of the invention will be described in detail below to enable those skilled in the art to readily implement them. However, the invention may be embodied in various forms, different from one another, and is therefore not limited to the examples described herein.

[0141] Examples and Comparative Examples

[0142] The substances used in the examples and comparative examples are as follows.

[0143] (1) Crosslinked copolymer: The crosslinked copolymers prepared in Examples 1 to 7 were used.

[0144] Preparation Example 1 - Crosslinked Copolymer A

[0145] In a mixture of 100 parts by weight of styrene monomer and 23 parts by weight of acrylonitrile, 0.2 parts by weight of azobisisobutyronitrile (AIBN), 0.3 parts by weight of tert-dodecyl mercaptan (TDDM), and 2.0 parts by weight of tricalcium phosphate were added under stirring at 200 rpm, and the temperature was raised to 70°C. Suspension polymerization was then carried out for 5 hours, with 0.2 parts by weight of tert-dodecyl mercaptan (TDDM) and 0.1 parts by weight of allyl methacrylate added in three 1-hour intervals as crosslinking agents. The resulting product was then washed and dehydrated, and dried in a fluidized bed dryer at 85°C for 90 minutes to produce crosslinked copolymer A in powder form.

[0146] Preparation Example 2 - Crosslinked Copolymer B

[0147] The crosslinked copolymer A prepared in Example 1 was pulverized to produce crosslinked copolymer B in powder form.

[0148] Preparation Example 3 - Crosslinked Copolymer C

[0149] The crosslinked copolymer A prepared in Example 1 was pulverized to produce crosslinked copolymer C in powder form.

[0150] Preparation Example 4 - Crosslinked Copolymer D

[0151] The crosslinked copolymer was prepared in the same manner as in Preparation Example 1, except that in Preparation Example 1, 0.3 parts by weight of allyl methacrylate was added as a crosslinking agent, and then the prepared crosslinked copolymer was pulverized to prepare crosslinked copolymer D in powder form.

[0152] Preparation Example 5 - Crosslinked Copolymer E

[0153] The crosslinked copolymer E in powder form was prepared by the same method as in Example 1, except that in Example 1, the mixture was stirred at 600 rpm.

[0154] Preparation Example 6 - Crosslinked Copolymer F

[0155] The crosslinked copolymer F in powder form was prepared by the same method as in Example 1, except that in Example 1, the mixture was stirred at 1,000 rpm.

[0156] Preparation Example 7 - Crosslinked Copolymer G

[0157] The crosslinked copolymer G in powder form was prepared by the same method as in Example 1, except that in Example 1, the mixture was stirred at 800 rpm.

[0158] (2) Matrix copolymer: Product name 97HC, manufactured by LG Chem Co., Ltd.

[0159] (3) Graft copolymer: Product name DP270, manufactured by LG Chem Co., Ltd.

[0160] Experimental Example 1 - Measurement of the physical properties of cross-linked copolymers D 50 The D-values ​​of the crosslinked copolymers produced in each of Preparation Examples 1 to 7 were measured using a laser diffraction particle size analyzer (manufactured by Sympatec GmbH, product name: HELOS / KR). 50 And listed in Tables 1 and 2 below.

[0161] HW ratio (a / b): The crosslinking copolymer, matrix copolymer and graft copolymer prepared in each of Examples 1 to 7 are added in the amounts described in Tables 1 and 2 below, and 0.2 parts by weight of heat stabilizer and 1 part by weight of slip additive are mixed in relative to a total of 100 parts by weight of crosslinking copolymer, matrix copolymer and graft copolymer to prepare the resin composition of each of Examples 1 to 7 and Comparative Examples 1 to 5.

[0162] The resin compositions produced in each of the above examples and comparative examples were loaded into an extrusion kneader (processing temperature: 220°C), extruded, and then injected to prepare samples. With the surface of the prepared samples observed using an optical microscope (manufactured by OLYMPUS, product name: OLS4000), half of the shortest axial length was denoted as 'a', and the longest axial length was denoted as 'b', and the HW ratio (a / b) was calculated. The average HW ratio (a / b) calculated for each crosslinked copolymer is listed in Tables 1 and 2.

[0163] Experimental Example 2 - Measuring the Physical Properties of Resin Compositions

[0164] The crosslinking copolymers, matrix copolymers, and graft copolymers prepared in Examples 1 to 7 were added in the amounts described in Tables 1 and 2 below, and 0.2 parts by weight of heat stabilizer and 1 part by weight of slip additive were mixed in relative to a total of 100 parts by weight of crosslinking copolymers, matrix copolymers, and graft copolymers to prepare the resin compositions of each of Examples 1 to 7 and Comparative Examples 1 to 5.

[0165] The resin compositions produced in each of the above examples and comparative examples were loaded into an extrusion kneader (processing temperature: 220°C), extruded, and then injected to prepare samples. The physical properties of the resin compositions were measured according to the following methods and are listed in Tables 1 and 2 below.

[0166] Gloss level: For samples with a thickness of 0.4 mm, the gloss level of the surface at 60° was measured using a gloss meter according to the evaluation method specified in ASTM D523. In this invention, the evaluation showed that the matte properties were excellent when the gloss level was below 7.5.

[0167] Cantilever beam impact strength: Measured on 1 / 4-inch thick samples according to ASTM 256. In this invention, it was evaluated that the impact resistance was excellent with a cantilever beam impact strength of 18 kg·cm / cm or higher.

[0168] Flow index: The flow index was measured at 220°C / 10 kg according to the evaluation method specified in ASTM D1238. In this invention, an flow index of 10 g / 10 min or higher is considered excellent.

[0169] Coefficient of variation of light reflection: The following method was used to measure a sample with a thickness of 0.4 mm using Python.

[0170] 1) Image capture of the sample: Using a DSLR camera (Canon 750 D) and a 200 mm × 200 mm surface light (white LED, collimated backlight LTS-3PFT), the image of the prepared sample was captured by setting the distance between the camera and the sample to 40 cm, the distance between the sample and the light to 100 cm, and the angle to 90°.

[0171] 2) Grayscale conversion of the sample image: The sample image is converted to grayscale (0 to 255) using the OpenCV library. In this case, a grayscale value is assigned to each pixel in the sample image, and this grayscale value is defined as the brightness.

[0172] 3) Image Reconstruction: The image is divided into a grid of 200μm × 200μm, and the brightness values ​​(grayscale values) of the corresponding pixels within each grid are averaged to reconstruct the image. In this case, each grid has an average brightness value.

[0173] 4) Brightness Correction: The target grid is designated as the first region, the 8 grids adjacent to the first region are designated as the second region, and the 16 grids adjacent to the second region are designated as the third region. Then, as correction factors for each region, 1 is assigned to the first region, -0.0625 to the second region, and -0.03125 to the third region. The corrected brightness value of the target grid is then derived according to the following mathematical formula 3.

[0174] [Mathematical Expression 3]

[0175] In the above mathematical formula 2, L is the corrected brightness value of the target mesh. 1 It is the brightness of the grid in the first region, L 2 1. L 2 2. L 2 3, ... and L 2 8 represents the brightness of the eight grids in the second region, and L 3 1. L 3 2. L 3 3、…、L 3 16 These are the brightness values ​​of the 16 grids in the third region.

[0176] 5) Derivation of mean and standard deviation: Determine the mean and standard deviation based on the corrected brightness value of the corresponding grid, and use the mean and standard deviation of the brightness obtained in this way to derive the light reflection variation coefficient through the following mathematical formula 2.

[0177] [Mathematical Expression 2]

[0178] C LR =D L / M L

[0179] C LR It is the coefficient of variation of light reflection, D L It is the standard deviation of brightness, and M L That is the average brightness.

[0180] Surface appearance quality: measured per unit area of ​​10 cm² The number of pinholes in a 10cm sample is evaluated, with no pinholes observed represented as 'o', 1 to 7 pinholes observed as '△', and 8 or more pinholes observed as 'x'.

[0181] [Table 1]

[0182] [Table 2]

[0183] Referring to Table 1, it can be confirmed that the resin compositions of Examples 1 to 7 contain D within the desired range. 50The resin composition is a crosslinked copolymer with an average HW ratio within the desired range and a light reflection variation coefficient below 1.35, exhibiting excellent gloss levels, excellent flow index, excellent impact strength, and excellent surface appearance quality.

[0184] It can be confirmed that in Comparative Example 1, which does not contain crosslinked copolymers, the gloss level is significantly higher than that in Examples 1 to 7.

[0185] It can be confirmed that, in the presence of D with a diameter greater than 60 μm 50 In Comparative Examples 2 to 5, which have an average HW ratio of less than 0.09 and a light reflection variation coefficient exceeding 1.35, the surface appearance quality and gloss level are lower than those in Examples 1 to 7.

Claims

1. A resin composition comprising: Graft copolymers comprising conjugated diene polymers, aromatic vinyl monomer units, and vinyl cyano monomer units; Matrix copolymers comprising aromatic vinyl monomer units and vinyl cyano monomer units; and Crosslinked copolymer, the crosslinked copolymer comprising: a crosslinked portion formed of a crosslinking functional compound, aromatic vinyl monomer units, and vinyl cyano monomer units, in, The particle size D of the crosslinked copolymer 50 The particle size is 30 μm to 60 μm, with a diameter D. 50 It refers to the particle size corresponding to the point on the particle size distribution map where the cumulative percentage based on weight reaches 50%. The average HW ratio of the crosslinked copolymer satisfies the following mathematical formula 1, and The coefficient of variation of light reflection calculated according to the following mathematical formula 2 is less than 1.

35. [Mathematical Expression 1] 0.09 ≤ average HW ratio ≤ 1 In the above mathematical formula 1, The average HW ratio is the average of the HW ratios (a / b) calculated for each crosslinked copolymer, observed when the surface of the resin composition is viewed using an optical microscope. a is the value of half the shortest axis length of each crosslinked copolymer observed when the surface of the resin composition is viewed under an optical microscope, and b is the longest axis length of each crosslinked copolymer as observed when the surface of the resin composition is viewed using an optical microscope. [Mathematical Expression 2] C LR =D L / M L In the above mathematical formula 2, C LR It is the coefficient of variation of light reflection, D L It is the standard deviation of brightness, and M L That is the average brightness.

2. The resin composition according to claim 1, wherein, The particle size D of the crosslinked copolymer when the cumulative percentage based on weight reaches 50% 50 The thickness ranges from 30μm to 50μm.

3. The resin composition according to claim 1, wherein, The crosslinking functional compound forming the crosslinked portion of the crosslinked copolymer is an acrylate-based compound or an allyl compound.

4. The resin composition according to claim 1, wherein, The crosslinking functional compound forming the crosslinked portion of the crosslinked copolymer is allyl methacrylate.

5. The resin composition according to claim 1, wherein, According to the evaluation method of ASTM D523, the gloss level at 60° measured by a gloss meter is below 7.

5.

6. The resin composition according to claim 1, wherein, Relative to a total of 100 parts by weight of the graft copolymer, the matrix copolymer, and the crosslinking copolymer, The resin composition contains 10 to 35 parts by weight of the crosslinked copolymer, and The resin composition contains 48 to 63 parts by weight of the matrix copolymer.

7. A method for preparing a resin composition, comprising: Step S1: Generate a crosslinked copolymer, wherein the particle size (D) is such that the cumulative percentage based on weight on the particle size distribution map reaches 50%. 50 The thickness is 30μm to 60μm, and the average HW ratio satisfies the following mathematical formula 1; as well as Step S2: Mix the crosslinked copolymer produced in step S1; the graft copolymer containing conjugated diene polymers, aromatic vinyl monomer units, and vinyl cyano monomer units; and the matrix copolymer containing aromatic vinyl monomer units and vinyl cyano monomer units. Step S1 includes step S1-1, which initiates the polymerization reaction by loading aromatic vinyl monomers, vinyl cyano monomers, and polymerization initiators into a reactor. Following step S1-1, step S1-2 involves polymerizing the crosslinking functional compound by loading it into the reactor in batches. [Mathematical Expression 1] 0.09 ≤ average HW ratio ≤ 1 In the above mathematical formula 1, The average HW ratio is the average of the HW ratios (a / b) calculated for each crosslinked copolymer, observed when the surface of the resin composition is viewed using an optical microscope. a is the value of half the shortest axis length of each crosslinked copolymer observed when the surface of the resin composition is viewed under an optical microscope, and b is the longest axis length of each crosslinked copolymer as observed when the surface of the resin composition is viewed using an optical microscope.

8. The method for preparing the resin composition according to claim 7, in, Step S1 also includes step S1-3 of pulverizing the product obtained in step S1-2.

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