Thermoplastic resin composition

Abstract

The present invention relates to a thermoplastic resin composition which contains an aromatic vinyl-vinyl cyanide-based crosslinked copolymer, has a 60 DEG glossiness of 25 or less as measured according to ASTM D523 using a glossmeter, has a light reflection variation coefficient of 2.0 or less as calculated by the following Equation 1, and can achieve matte performance even by injection molding. [Equation 1] CLR = DL / ML (wherein CLR is the coefficient of variation in light reflection, DL is the standard deviation of the light emission intensity, and ML is the average light emission intensity.

Description

Technical Field

[0001] Cross-reference to related applications

[0002] This application claims the priority and benefits of Korean Patent Application No. 2022-0139506, filed on October 26, 2022, and Korean Patent Application No. 2022-0138522, filed on October 25, 2022. The entire contents of these two patent applications are incorporated herein by reference.

[0003] The present invention relates to a thermoplastic resin composition capable of achieving a matte property. Background Art

[0004] Generally, acrylonitrile-butadiene-styrene (hereinafter referred to as ABS) resin has excellent impact resistance and excellent processability. Therefore, ABS resin is widely used in various applications such as automobiles, electrical and electronic products, office supplies, household appliances, toys, and stationery. However, due to the double bonds of the butadiene rubber used as an impact modifier, the ABS resin is easily oxidized by oxygen, ultraviolet rays, light, and heat, which leads to discoloration and a decrease in appearance characteristics. Therefore, there are limitations in using the ABS resin as an exterior material. Even when used as an interior material, the ABS resin cannot meet the requirements of customers due to discoloration.

[0005] With the recent trend of high-end household appliances and automotive interior materials, attention has been focused on sensitive resins that can replace cold, artificially glossy materials and exhibit low gloss and a soft texture without painting. With the development trend of high-end household appliances and automotive interior materials, due to indoor air quality regulations and environmental issues, the automotive industry is excluding coating and painting processes and using low-gloss resins.

[0006] One method for preparing a low-gloss resin is to produce a low-gloss effect through diffuse reflection, which scatters incident light by significantly adjusting the smoothness of the resin surface. Specifically, a method of preparing large rubber particles with an average particle size of 1 μm or more can be used. Although the resin prepared in this way can have a reduced gloss deviation on the entire surface of the molded article, the low-gloss effect is insufficient, and the heat resistance and impact strength are reduced.

[0007] Another method is to emboss the mold to make the surface of the molded product uneven, thereby producing a low gloss effect on the surface of the injection-molded product. However, the products prepared in this way have an excellent low gloss effect, but each product shape requires a separate mold, and due to the uneven gloss of the resin itself, the gloss increases partially. As the size of the molded product using the low gloss resin becomes larger, gloss deviation occurs in which high gloss is unevenly expressed during the molding process. To solve these problems, mold analysis is used to adjust the injection molding conditions and the mold gate position, but there are limitations.

[0008] Another method is to prepare a low gloss resin by graft copolymerizing a monomer such as ethylene-unsaturated carboxylic acid onto the resin. Although this method provides a resin with overall good physical properties, the heat resistance is rapidly reduced.

[0009] U.S. Patent Registration No. 4,460,742 discloses a low gloss resin composition using a crosslinked copolymer. It exhibits a low gloss effect by adding large diameter rubber particles or a matting agent. However, an excessive amount of matting agent is required, resulting in a reduction in impact strength and heat resistance.

[0010] Therefore, there is a need to develop a new low gloss thermoplastic material that has excellent weather resistance, heat resistance, and low gloss characteristics, and at the same time exhibits low gloss characteristics uniformly over the entire surface of the molded product.

[0011] [Prior Art Documents]

[0012] [Patent Documents]

[0013] (Patent Document 1) U.S. Patent Registration No. 4,460,742 Summary of the Invention

[0014] Technical Problem

[0015] The present invention aims to provide a matte thermoplastic resin composition having a smooth and matte surface by injection molding without additional etching treatment of the mold surface.

[0016] Technical Solution

[0017] To solve the above problems, the present invention provides a resin composition comprising an aromatic vinyl-vinyl cyanide crosslinked copolymer, wherein the 60° gloss measured using a gloss meter according to ASTM D523 is 25 or less, and the coefficient of variation of light reflection calculated by the following Equation 1 is 2.0 or less.

[0018] [Equation 1]

[0019] C LR =D L / ML

[0020] In Equation 1, C LR is the coefficient of variation of light reflection, D L is the standard deviation of the luminous intensity, and M L is the average luminous intensity.

[0021] Another aspect of the present invention provides an injection molded article including the thermoplastic resin composition.

[0022] Advantageous Effects

[0023] The resin composition according to the present invention has low gloss, and can have a matte property and ensure a smooth surface by adjusting the coefficient of variation of light reflection to a low level, and this matte and smooth surface is achieved by injection molding without additional etching treatment of the mold surface. Detailed Description

[0024] Hereinafter, the present invention will be described in further detail to help understand the present invention.

[0025] The terms and words in this specification and claims should not be construed as limited to their conventional or dictionary meanings, but should be understood as meanings and concepts consistent with the technical concept of the present invention based on the principle that the inventor can appropriately define the terms to best describe their invention.

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

[0027] The term "composition" used in the present invention includes not only reaction products and decomposition products formed from the materials of the composition, but also mixtures containing the materials of the composition.

[0028] The term "monomer unit" or "crosslinked unit" used in the present invention can be a repeating unit formed when a compound used as a monomer or a compound used as a crosslinking agent participates in a polymerization or crosslinking reaction, a structure derived therefrom, or the substance itself.

[0029] The term "derivative" used in the present invention can be a compound having a structure in which one or more hydrogen atoms constituting the original compound are replaced by a halogen group, an alkyl group, or a hydroxyl group.

[0030] In the present invention, the "polymerization conversion rate" refers to the degree to which monomers are polymerized through a polymerization reaction to form a polymer. After taking out a part of the polymer in the reactor as a sample during the polymerization process, the weight of the polymer without moisture is calculated by Equation 3 below. Then, the sample is dissolved in a tetrahydrofuran (THF) solvent and precipitated with methanol (MeOH) to remove unreacted monomers. The precipitated suspended solids are dried to obtain the polymer. After measuring the weight of the polymer, the polymerization conversion rate is calculated using Equation 4 below.

[0031] [Equation 3]

[0032] (Actual weight of the polymer) = (Weight of the collected polymer) - (Weight of the collected polymer × Moisture content)

[0033] [Equation 4]

[0034] Polymerization conversion rate (%) = [(Weight of the polymer obtained by drying) / (Actual weight of the polymer)] × 100

[0035] Thermoplastic resin composition

[0036] The resin composition according to the present invention contains an aromatic vinyl-vinyl cyanide crosslinked copolymer, has a 60° glossiness of 25 or less as measured using a gloss meter according to ASTM D523, and has a coefficient of variation of light reflection of 2.0 or less calculated by Equation 1 below.

[0037] [Equation 1]

[0038] C LR = D L / M L

[0039] In Equation 1, C LR is the coefficient of variation of light reflection, D L is the standard deviation of the luminous intensity, and M L is the average luminous intensity.

[0040] According to an embodiment of the present invention, the glossiness of the resin composition is 25 or less, preferably 20 or less, more preferably 17 or less, and even more preferably 15 or less. Glossiness is a representative value that can represent glossiness (high gloss and low gloss) or matte. The glossiness of most commercially available matte molded products is about 30, which actually cannot be regarded as matte. However, when using the resin composition of the present invention, a very low level of glossiness of 25 or less can be achieved, thus enabling the realization of matte products.

[0041] Existing matte products are typically manufactured by roughening the surface of an injection mold through etching treatment and then injecting resin to give the surface the property of diffuse reflection. However, this method is not suitable for mass production because the processing performance decreases as the injection mold wears.

[0042] On the other hand, some molded products achieve matte by post-treating low-gloss products. For example, a pattern on the surface is formed by applying a co-extruded film containing a crosslinked product or by applying a crosslinked product to the product and then performing ultraviolet curing. However, when using this method, the product has a very high defect rate, low reproducibility of physical properties, and this method is not cost-effective because additional processes such as coating and curing are required.

[0043] The resin composition according to an embodiment of the present invention has the same glossiness as above and a coefficient of variation of light reflection of 2.0 or less, and thus, a matte molded product having a smooth surface can be provided. The coefficient of variation of light reflection can be 2.0 or less, preferably 1.9 or less, more preferably 1.8 or less, still more preferably 1.7 or less, and most preferably 1.5 or less.

[0044] The coefficient of variation of light reflection not only reflects the smoothness of the surface of the molded product but also reflects the glossiness, which indicates a matte and smooth surface, that is, diffuse reflection occurs equally anywhere on the surface, and thus, a high-quality matte molded product can be provided. In other words, a coefficient of variation of light reflection greater than 2.0 indicates that the surface is not smooth, and thus, diffuse reflection does not occur in any part of the surface.

[0045] The coefficient of variation of light reflection can be obtained using Phyton in the following manner.

[0046] 1) Sample imaging: Using a digital single-lens reflex camera (Canon 750D) and a 200 mm × 200 mm white LED (collimated backlight LTS-3PFT), when the distance between the camera and the sample is set to 40 cm, the distance between the sample and the light is set to 100 cm, and the angle is 90°, the prepared sample is photographed and imaged.

[0047] 2) Grayscale conversion of the sample image: The sample image is converted to grayscale (0 to 255) using the OpenCV library. Gray-scale values are assigned to each pixel in the sample image, and the gray-scale values are used as the light emission intensity.

[0048] 3) Image reconstruction: The image is reconstructed by dividing the image into 200 μm × 200 μm grids and averaging the light emission intensity values (gray-scale values) of the pixels in each grid. Each grid has an average light emission intensity value.

[0049] 4) Luminance correction: Set the target grid as Region 1, set the 8 grids adjacent to Region 1 as Region 2, and set the 16 grids adjacent to Region 2 as Region 3. After respectively assigning 1, -0.0625, and -0.03125 as correction factors to Region 1, Region 2, and Region 3, use Equation 2 below to derive the corrected luminance value of the target grid.

[0050] [Equation 2]

[0051]

[0052] In Equation 2, L is the corrected luminance value of the target grid, L 1 is the luminance of the grid in Region 1, L 2 1 、L 2 2 、L 2 3 、…、L 2 8 are the respective luminances of the 8 grids in Region 2, L 3 1 、L 3 2 、L 3 3 、…、L 3 16 are the respective luminances of the 16 grids in Region 3.

[0053] The correction factor is designed to readjust the luminance considering the visual suppression effect and can minimize the error caused by visual illusion, where when observed with the naked eye, the luminance of the target grid may be differently evaluated due to the luminances of the surrounding grids. Specifically, for the "matte" of the product, it is more important to be judged as matte through human visual perception. Therefore, not only the value measured by the device needs to indicate matte, but also it needs to be judged as matte through visual perception. Thus, the correction factor can be applied to the measured value so that the measured value obtained by the device is the same as the actual visual effect considering visual illusion.

[0054] 5) Mean value and standard deviation: After obtaining the mean value and standard deviation from the corrected luminance values of the respective grids, substitute the mean value and standard deviation of the luminance into Equation 1 to obtain the coefficient of variation of light reflection.

[0055] The resin composition according to an embodiment of the present invention has low gloss and a low coefficient of variation of light reflection. Therefore, a matte molded article with a smooth surface can be provided, and these properties can be achieved by including an aromatic vinyl-vinyl cyanide crosslinked copolymer, which can solve the problems existing in the existing matte molded articles.

[0056] (1) Aromatic vinyl-vinyl cyanide crosslinked copolymer and method for preparing the same

[0057] According to one embodiment of the present invention, the resin composition comprises an aromatic vinyl-vinyl cyanide crosslinked copolymer, and based on 100 parts by weight of the resin composition, the content of the aromatic vinyl-vinyl cyanide crosslinked copolymer can be from 1 part by weight to 30 parts by weight, preferably from 3 parts by weight to 20 parts by weight.

[0058] The crosslinked copolymer provides surface properties to the resin composition such that light can be diffusely reflected from the surface, and the copolymer can be prepared in a higher strength form due to crosslinking and is uniformly distributed in the matrix resin. When the crosslinked copolymer is included in the resin composition, the glossiness and the coefficient of variation of light reflection can be very low. When the crosslinked copolymer is included in the above range, the above effects can be more easily achieved.

[0059] According to one embodiment of the present invention, the crosslinked copolymer may include a crosslinked portion containing a crosslinking functional compound, an aromatic vinyl monomer unit, and a vinyl cyanide monomer unit.

[0060] According to one embodiment of the present invention, the crosslinked portion may contain a crosslinking functional compound unit, and the crosslinking functional compound may include one or more selected from silicone compounds, acrylic compounds, and vinyl compounds, and the crosslinked portion may be composed of units derived from these compounds.

[0061] The crosslinked copolymer according to one embodiment of the present invention may have a very uniformly distributed crosslinked portion, and due to the appropriate degree of distribution of the crosslinked portion, the fluidity between all chains can be maintained.

[0062] The crosslinked copolymer may be a random copolymer and have a uniform composition of aromatic vinyl monomer units and vinyl cyanide monomer units in the copolymer. The uniform composition of the monomer units may mean that the ratio of the monomer units present in the growing polymer formed by the polymerization reaction of the monomers remains constant. In a specific example, as the polymerization proceeds, that is, during the polymerization time, whenever a part of the polymer in the reactor is collected as a sample, the ratio of each monomer unit forming the polymer remains constant.

[0063] According to one embodiment of the present invention, the aromatic vinyl monomer units and the vinyl cyanide monomer units may be repeating units respectively formed from the aromatic vinyl monomer units and the vinyl cyanide monomer units participating in the polymerization reaction. As a specific example, the polymerization reaction may be a radical polymerization reaction, and thus, the repeating units may be derived from the carbon-carbon double bonds present in the aromatic vinyl monomers and the vinyl cyanide monomers.

[0064] According to an embodiment of the present invention, a method for preparing an aromatic vinyl-vinyl cyanide crosslinked copolymer includes: initiating polymerization by adding a first reaction solution containing an aromatic vinyl monomer and a vinyl cyanide monomer to a reactor (S1); and performing polymerization while adding a second reaction solution containing a crosslinking functional compound to the reactor (S2), wherein the second reaction solution can be added in two or more divided portions.

[0065] Step (S1) is a step of initiating polymerization, which may include adding the reaction solution to the reactor and raising the temperature of the reactor to a predetermined temperature. When the internal temperature of the reactor even rises above the predetermined temperature in step (S1), the polymerization proceeds in the presence of a polymerization initiator. The internal temperature of the reactor in step S1 can be raised to about 60°C to 120°C, preferably 70°C to 110°C.

[0066] According to an embodiment of the present invention, the aromatic vinyl monomer 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. As a specific example, it may be styrene.

[0067] Based on 100 parts by weight of all the monomers added including the aromatic vinyl monomer and the vinyl cyanide monomer, the addition amount of the aromatic vinyl monomer may be 30 parts by weight to 95 parts by weight, 40 wt% to 90 wt%, 50 parts by weight to 85 parts by weight, or 60 parts by weight to 80 parts by weight. Within this range, a copolymer with a high polymerization conversion rate can be obtained, and the copolymer can have excellent compatibility with a thermoplastic resin while maintaining its mechanical properties. Preferably, 10 wt% to 50 wt% of the aromatic vinyl monomer based on the total addition amount can be added to the first reaction solution in step (S1), and the remaining 50 wt% to 90 wt% can be included in the second reaction solution in step (S2) and added in two or more divided portions.

[0068] According to an embodiment of the present invention, the vinyl cyanide monomer may be one or more selected from acrylonitrile, methacrylonitrile, ethylacrylonitrile, and their derivatives. As a specific example, it may be acrylonitrile.

[0069] According to an embodiment of the present invention, based on the total amount of monomers including the addition of aromatic vinyl monomers and vinyl cyanide monomers, the addition amount of vinyl cyanide monomers can be 5 parts by weight to 70 parts by weight, 10 parts by weight to 60 parts by weight, 15 parts by weight to 50 parts by weight, or 20 parts by weight to 40 parts by weight. Within this range, a copolymer with a high polymerization conversion rate can be obtained, and while having excellent compatibility with the thermoplastic resin, the mechanical properties of the copolymer can be maintained. Preferably, 10% to 50% by weight of vinyl cyanide monomers based on the total addition amount can be added to the first reaction solution in step (S1), and the remaining 50% to 90% can be included in the second reaction solution in step (S2) and added in more than two divided portions.

[0070] According to an embodiment of the present invention, the method for preparing the crosslinked copolymer can be carried out by suspension polymerization, and the first reaction solution in step S1 is a solvent for carrying out the polymerization and can further contain one or more additives selected from polymerization initiators, water-soluble solvents, dispersants, dispersion aids, and molecular weight regulators, and the polymerization can be carried out in the presence of these additives.

[0071] According to an embodiment of the present invention, the polymerization initiator is used to easily initiate the polymerization and is not particularly limited as long as it does not adversely affect the polymerization, and can be, for example, one or more selected from 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane, bis(tert-butylperoxy-isopropyl)benzene, tert-butylcumyl peroxide, di(tert-amyl) peroxide, dicumyl peroxide, butyl 4,4-bis(tert-butylperoxy)valerate, tert-butyl perbenzoate, 2,2-bis(tert-butylperoxy)butane, tert-amyl perbenzoate, tert-butyl peracetate, tert-butyl peroxy(2-ethylhexyl) carbonate, tert-butyl peroxyisopropyl carbonate, tert-butyl peroxy-3,5,5-trimethylhexanoate, 1,1-bis(tert-butylperoxy)cyclohexane, tert-amyl peracetate, tert-amyl peroxy(2-ethylhexyl) carbonate, 1,1-bis(tert-butylperoxy)-3,5,5-trimethylcyclohexane, 1,1-bis(tert-amylperoxy)cyclohexane, tert-butyl monoperoxy malate, 1,1'-azobis(hexahydrobenzonitrile), and 1,1'-azobis(cyclohexane-1-carbonitrile), specifically, one or more selected from dicumyl peroxide, 1,1-bis(tert-butylperoxy)cyclohexane, and 1,1'-azobis(cyclohexanecarbonitrile).

[0072] Based on the total amount of 100 parts by weight of monomers used in the polymerization, i.e., the total amount of aromatic vinyl monomers and vinyl cyanide monomers, the amount of the polymerization initiator can be from 0.001 part by weight to 0.5 part by weight, specifically from 0.003 part by weight to 0.45 part by weight, or from 0.06 part by weight to 0.25 part by weight. When the polymerization initiator is used within this range, the polymerization reaction can proceed more easily, thereby improving the polymerization conversion rate.

[0073] According to one embodiment of the present invention, the water-soluble solvent can be ion-exchanged water or deionized water. Meanwhile, according to one embodiment of the present invention, the monomer droplets can contain a water-soluble solvent, and the water-soluble solvent can be ion-exchanged water or deionized water, and can be the same as the water-soluble solvent added before initiating the polymerization.

[0074] According to one embodiment of the present invention, the dispersant can be one or more selected from 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, sorbitan laurate, sorbitan trioleate, polyoxyethylene, sodium dodecyl sulfate, sodium dodecylbenzenesulfonate, and sodium dioctyl sulfosuccinate. As a specific example, it can be tricalcium phosphate.

[0075] According to one embodiment of the present invention, based on the total amount of 100 parts by weight of the added monomers, the amount of the dispersant can be from 0.5 part by weight to 2.0 parts by weight, from 0.5 part by weight to 1.5 parts by weight, or from 1.0 part by weight to 1.5 parts by weight. Within this range, a copolymer with more uniform particles can be prepared by improving the dispersion stability of the monomers in the polymerization system.

[0076] According to one embodiment of the present invention, the method for preparing the crosslinked copolymer can be carried out by further including a dispersion aid. As a specific example, the dispersion aid can be a polyoxyethylene-based dispersion aid. As a more specific example, it can be polyoxyethylene alkyl ether phosphate. In this case, the polymerization stability can be excellent.

[0077] According to one embodiment of the present invention, the molecular weight regulator can be, for example, one or more selected from α-methylstyrene dimer, tert-dodecyl mercaptan, n-dodecyl mercaptan, octyl mercaptan, carbon tetrachloride, dichloromethane, dibromomethane, tetraethylthiuram disulfide, dipentamethylenethiuram disulfide, and diisopropylxanthogen disulfide. As a specific example, it can be tert-dodecyl mercaptan.

[0078] According to an embodiment of the present invention, based on the total amount of monomers added of 100 parts by weight, the amount of the molecular weight regulator may be from 0.01 part by weight to 0.40 part by weight, from 0.05 part by weight to 0.30 part by weight, or from 0.10 to 0.25 part by weight. Within this range, a copolymer with an appropriate weight average molecular weight can be prepared.

[0079] According to an embodiment of the present invention, in step (S2), the second reaction solution containing the crosslinking functional compound may be added in portions more than twice, preferably more than three times. The crosslinking functional compound may include functional groups such as siloxanyl, vinyl, or acrylic groups, and two or more functional groups, preferably three or more functional groups, may be present in one crosslinking functional compound.

[0080] When polymerization is carried out by adding the crosslinking functional compound (hereinafter referred to as "crosslinking agent") only at the start of polymerization, the crosslinking effect will be relatively low. In other words, the concentration of the crosslinking agent is relatively high at the start of polymerization, so there is a high probability of side reactions where the crosslinking agents combine with each other. And as the concentration of the crosslinking agent decreases in the later stage of polymerization, it may be difficult to uniformly distribute the crosslinked portions in the copolymer chain, and since the production of the crosslinked copolymer does not proceed smoothly, the yield of the crosslinked copolymer may be significantly reduced. This may lead to an increase in gloss and the coefficient of variation of light reflection.

[0081] According to an embodiment of the present invention, the crosslinking functional compound is added in step (S2), and it may be added immediately after step (S1) and in portions more than twice, preferably more than three times, during the polymerization process.

[0082] According to an embodiment of the present invention, the time interval between the portionwise additions of the crosslinking functional compound in step (S2) may be from 1% to 30% of the total polymerization time. When there is a time interval between the portionwise additions, the degree of crosslinking within the entire copolymer chain can be constant at an appropriate level, and the crosslinking density can be excellent, which may be crucial for making the surface of the resin molded article have diffuse reflectivity. The crosslinking agent may be added in portions for 20% to 70% of the total polymerization time, and preferably the portionwise addition starts and ends within this time range to provide a sufficient crosslinking effect.

[0083] According to an embodiment of the present invention, the crosslinking functional compound may be added in portions immediately after step (S1), and the addition in portions may be terminated before the polymerization conversion rate reaches 50% to 75%.

[0084] According to an embodiment of the present invention, based on the total amount of monomers added of 100 parts by weight, the amount of the crosslinking functional compound added in a divided manner during the polymerization process in step (S2) may be from 0.05 parts by weight to 0.30 parts by weight, preferably from 0.05 parts by weight to 0.20 parts by weight, more preferably from 0.05 parts by weight to 0.15 parts by weight. When the amount of the crosslinking functional compound added is less than 0.05 parts by weight, due to the lack of the crosslinking functional compound constituting the crosslinked product, it may be impossible to achieve the desired level of crosslinking degree, and thus it is difficult to achieve low gloss. On the other hand, when the amount of the crosslinking functional compound added exceeds 0.3 parts by weight, the excessive crosslinking degree may cause imbalance, and the oligomers formed due to the reaction between crosslinking agents and the reaction between crosslinking agents and monomers may adversely affect the matte performance, and the significantly reduced polymerization stability may cause polymerization failure and low yield. The respective amounts of the crosslinking functional compound used in the divided addition may be the same or different, and preferably the amounts are adjusted so that the change in the amounts is not significant, and the added amount may be the total amount added in a divided manner.

[0085] As described above, the crosslinking functional compound is a compound having two or more vinyl groups, acrylic groups or siloxanyl groups, and may be, for example, a silicone-based compound or a polyene compound. The polyene crosslinking agent may be, for example, a vinyl crosslinking agent or an acrylic crosslinking agent. 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 divinylbenzene may be preferably used.

[0086] The silicone crosslinking agent can be, for example, 1,3,5-triisopropyl-1,3,5-trivinyl-cyclotrisiloxane, 1,3,5,7-tetraisopropyl-1,3,5,7-tetravinyl-cyclotetrasiloxane, 1,3,5,7,9-pentaisopropyl-1,3,5,7,9-pentavinyl-cyclopentasiloxane, 1,3,5-tri-sec-butyl-1,3,5-trivinyl-cyclotrisiloxane, 1,3,5,7-tetra-sec-butyl-1,3,5,7-tetravinyl-cyclotetrasiloxane, 1,3,5,7,9-pentasec-butyl-1,3,5,7,9-pentavinyl-cyclopentasiloxane, 1,3,5-trimethyl-1,3,5-trivinyl-cyclotrisiloxane, 1,3,5,7-tetramethyl-1,3,5,7-tetravinyl-cyclotetrasiloxane, 1,3,5,7,9-pentamethyl-1,3,5,7,9-pentavinyl-cyclopentasiloxane, 1,3,5-triethyl-1,3,5-trivinyl-cyclotrisiloxane, 1,3,5,7-tetraethyl-1,3,5,7-tetravinyl-cyclotetrasiloxane, 1,3,5,7,9-pentaethyl-1,3,5,7,9-pentavinyl-cyclopentasiloxane or a mixture thereof, and divinylsilane, trivinylsilane, dimethyldivinylsilane, divinylmethylsilane, methyltrivinylsilane, diphenyldivinylsilane, divinylphenylsilane, trivinylphenylsilane, divinylmethylphenylsilane, tetravinylsilane, dimethyldivinylsiloxane, divinyldiphenylchlorosilane, etc. can be mixed and used, but not limited thereto.

[0087] The silicone crosslinking agent can preferably be 1,3,5-trimethyl-1,3,5-trivinyl-cyclotrisiloxane, 1,3,5,7-tetramethyl-1,3,5,7-tetravinyl-cyclotetrasiloxane, 1,3,5,7,9-pentamethyl-1,3,5,7,9-pentavinyl-cyclopentasiloxane, 1,3,5-triethyl-1,3,5-trivinyl-cyclotrisiloxane, 1,3,5,7-tetraethyl-1,3,5,7-tetravinyl-cyclotetrasiloxane, 1,3,5,7,9-pentaethyl-1,3,5,7,9-pentavinyl-cyclopentasiloxane or a mixture thereof, more preferably 1,3,5,7-tetramethyl-1,3,5,7-tetravinyl-cyclotetrasiloxane, etc.

[0088] According to an embodiment of the present invention, the method for preparing an aromatic vinyl-vinyl cyanide crosslinked copolymer may include: initiating polymerization by adding a first reaction solution containing an aromatic vinyl monomer and a vinyl cyanide monomer to a reactor (S1); and polymerizing while adding a second reaction solution containing a crosslinking functional compound to the reactor (S2), wherein the second reaction solution can be added in two or more divided portions, and the second reaction solution may further contain one or more of a molecular weight regulator and a polymerization initiator.

[0089] When the second reaction solution containing a molecular weight regulator and / or a polymerization initiator is added to the crosslinking functional compound in portions, a synergistic effect can be produced on the desired effect, and since it is easier to control the reactivity between monomers and the reaction between the polymer chain and the crosslinking agent, a smooth matte molded article having a low gloss and a low coefficient of variation in light reflectance can be obtained.

[0090] According to an embodiment of the present invention, the crosslinking functional compound is added in portions in step (S2), but may be included in the first reaction solution to initiate polymerization. Adding the crosslinking functional compound to the first reaction solution does not replace the effect of adding the crosslinking functional compound in step (S2), but an additional crosslinking effect can be achieved by adding the crosslinking agent before initiating polymerization. However, when adding the crosslinking functional compound to the first reaction solution in step (S1), since attention should be paid to preventing the formation of oligomers due to the reaction with monomers and reducing the polymerization stability due to the high reactivity of the crosslinking agent, a compound having a slow reaction rate due to relatively low reactivity can be preferably added. Based on the total amount of monomers added of 100 parts by weight, the addition amount of the crosslinking functional compound can be 0.1 part by weight to 5.0 parts by weight, preferably 0.5 part by weight to 3.0 parts by weight, more preferably 0.7 part by weight to 1.0 part by weight, and a crosslinking functional compound different from the crosslinking functional compound added in step (S2) is preferably used.

[0091] According to an embodiment of the present invention, the method for preparing a crosslinked copolymer may further include adding a molecular weight regulator during the polymerization process in step (S1), and the molecular weight regulator may be added in portions more than twice. In this case, effects and functions similar to those when adding a polyene crosslinking agent in portions can be expected, and it can have a synergistic effect on the effect of adding a polyene crosslinking agent in portions.

[0092] In the method for preparing a copolymer according to an embodiment of the present invention, the polymerization in step (S1) may be carried out in a temperature range of 50°C to 150°C, preferably 60°C to 130°C, more preferably 65°C to 120°C. When the polymerization is carried out in this temperature range, it can be beneficial to obtain a final polymerization conversion rate, desired particle size characteristics, and other polymer properties.

[0093] (2) Aromatic vinyl-vinyl cyanide non-crosslinked copolymer

[0094] According to an embodiment of the present invention, the resin composition may comprise an aromatic vinyl-vinyl cyanide non-crosslinked copolymer. The aromatic vinyl-vinyl cyanide non-crosslinked copolymer may include aromatic vinyl monomer units and vinyl cyanide monomer units, and the types of these monomers may be similarly selected from the types used for the above-mentioned crosslinked copolymer.

[0095] The non-crosslinked copolymer may act as a matrix in the resin composition, and the non-crosslinked copolymer has excellent heat resistance, impact resistance and fluidity, and can act as a basis for achieving excellent physical properties of resin molded articles. The non-crosslinked copolymer can generally be obtained by applying commercially available resins, and can be obtained by commercial methods or in the same manner as the above-mentioned preparation method of the crosslinked copolymer except that a crosslinking agent is not used, but is not particularly limited thereto.

[0096] (3) Graft copolymer

[0097] According to an embodiment of the present invention, the graft copolymer may include a conjugated diene polymer, aromatic vinyl monomer units and vinyl cyanide monomer units, or may include an acrylic polymer, aromatic vinyl monomer units and vinyl cyanide monomer units. In other words, the graft copolymer may be an acrylonitrile-butadiene-styrene copolymer or an acrylic-styrene-acrylonitrile (ASA) graft copolymer prepared based on an acrylic polymer.

[0098] The acrylonitrile-butadiene-styrene copolymer provides excellent molding properties and impact resistance to the thermoplastic resin composition, and may be a graft copolymer having a core-shell structure, the core-shell structure including: a core including conjugated diene monomer units; and a shell surrounding the core including aromatic vinyl monomer units and vinyl cyanide monomer units.

[0099] According to an embodiment of the present invention, the conjugated diene monomer of the above graft copolymer may be one or more selected from 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.

[0100] The types of the aromatic vinyl monomer and the vinyl cyanide monomer may be similarly selected from the types used for the above-mentioned crosslinked copolymer.

[0101] According to an embodiment of the present invention, the acrylonitrile-butadiene-styrene copolymer can be prepared by emulsion polymerization and emulsion graft polymerization, and can be, for example, prepared by emulsion polymerization of a conjugated diene monomer to prepare a core (or seed) as a rubber polymer, and adding a vinyl cyanide monomer and an aromatic vinyl monomer to the core and performing emulsion graft polymerization.

[0102] The acrylonitrile - butadiene - styrene copolymer can comprise: 30% to 70% by weight of a core, the core comprising conjugated diene monomer - derived units; and 30% to 70% by weight of a shell surrounding the core, the shell comprising aromatic vinyl monomer - derived units and vinyl cyanide monomer - derived units, wherein the shell can comprise aromatic vinyl monomer - derived units and vinyl cyanide monomer - derived units in a weight ratio of 7:3 to 8:2. In this case, the copolymer can have excellent impact resistance, mechanical properties, and molding properties.

[0103] The graft copolymer can be obtained using commercially available resins and can be obtained by commercially available methods, and is not particularly limited thereto.

[0104] (4) Others

[0105] As needed, the resin composition according to an embodiment of the present invention can further comprise one or more additives selected from impact modifiers, lubricants, heat stabilizers, anti - dripping agents, antioxidants, light stabilizers, ultraviolet blockers, pigments, and inorganic fillers, and based on 100 parts by weight of the copolymer and the thermoplastic resin, the amount of the additive can be 5.0 parts by weight or less, or 0.1 part to 1.0 part by weight.

[0106] In addition, the additives can be used without particular limitation as long as they are used in the thermoplastic resin composition. For example, the anti - dripping agent can be one or more selected from Teflon, polyamide, polysilicon, polytetrafluoroethylene (PTFE), and tetrafluoroethylene - hexafluoropropylene (TFE - HFP) copolymer to improve flame retardancy, and the inorganic filler can be one or more selected from barium sulfate, barium glass filler, and barium oxide.

[0107] Molded article

[0108] According to the present invention, a molded article comprising the above - mentioned resin composition is provided. For example, the molded article can be used in various industrial fields such as electrical and electronic products and automotive parts. Common methods including extrusion, injection, and casting can be applied as the molding method. For example, compared with products in which the mold surface is corroded to provide a matte - finished molded article, the molded article according to the present invention does not require corrosion treatment of the mold surface and can provide a molded article with a matte and smooth surface in the injection - molded state without post - treatment of the molded article.

[0109] Examples

[0110] In the following, embodiments of the present invention will be described in detail so that those skilled in the art can easily implement the present invention. However, the present invention can be implemented in various different forms and is not limited to the examples described in this specification.

[0111] * Copolymer yield: It represents the degree to which monomers are polymerized to form a polymer through a polymerization reaction. After collecting a part of the polymer in the reactor as a sample after polymerization, the weight of the polymer without moisture is calculated through Equation 3 below. Then, the sample is dissolved in a tetrahydrofuran (THF) solvent, precipitated with methanol (MeOH) to remove unreacted monomers, the precipitated suspended solids are dried to obtain the polymer, and after measuring the weight of the polymer, the polymerization conversion rate is calculated using Equation 4 below.

[0112] [Equation 3]

[0113] (Actual weight of polymer) = (Weight of collected polymer) - (Weight of collected polymer × Moisture content)

[0114] [Equation 4]

[0115] Polymerization conversion rate (%) = [(Weight of polymer obtained by drying) / (Actual weight of polymer)] × 100

[0116] Preparation Example 1

[0117] 120 parts by weight of ion-exchanged water, 77 parts by weight of styrene, 23 parts by weight of acrylonitrile, 0.2 part by weight of 1,1′-azobis(cyclohexane-1-carbonitrile), 0.2 part by weight of tert-dodecyl mercaptan, and 0.7 part by weight of 1,3,5-trimethyl-1,3,5-trivinyl-cyclotrisiloxane were added to a reactor. After raising the temperature of the reactor to 70 °C, 0.14 part by weight of allyl methacrylate was added to the reactor in three portions at 1-hour intervals, and after polymerization for a total of 5 hours, a crosslinked copolymer (bead-like) was prepared through washing, dehydration, and drying, with a yield of 96%.

[0118] Per part by weight based on the total amount of 100 parts by weight of the added monomers.

[0119] Preparation Example 2

[0120] A crosslinked copolymer was prepared in the same manner as in Preparation Example 1, except that 0.2 part by weight of allyl methacrylate was added, with a yield of 95%.

[0121] Preparation Example 3

[0122] A crosslinked copolymer was prepared in the same manner as in Preparation Example 2, except that dodecyl mercaptan was not added to the reactor, and after raising the temperature, 0.2 parts by weight of allyl methacrylate and 0.2 parts by weight of dodecyl mercaptan were added to the reactor in three portions at 1-hour intervals, and the yield was 95%.

[0123] Preparation Example 4

[0124] A crosslinked copolymer was prepared in the same manner as in Preparation Example 1, except that 0.3 parts by weight of allyl methacrylate was added, and the yield was 92%.

[0125] Preparation Example 5

[0126] A crosslinked copolymer was prepared in the same manner as in Preparation Example 1, except that 0.2 parts by weight of allyl methacrylate was added to the reactor in two portions at 1-hour intervals, and the yield was 91%.

[0127] Comparative Preparation Example 1

[0128] A crosslinked copolymer was prepared in the same manner as in Preparation Example 1, except that 0.2 parts by weight of allyl methacrylate was added in one batch at the start of polymerization instead of after raising the temperature of the reactor, and the yield was 86%.

[0129] Comparative Preparation Example 2

[0130] A crosslinked copolymer was prepared in the same manner as in Comparative Preparation Example 1, except that 0.5 parts by weight of allyl methacrylate was added, and the yield was 80%.

[0131] Example 1

[0132] A resin composition was prepared by mixing 20 parts by weight of the aromatic vinyl-vinyl cyanide crosslinked copolymer prepared in Preparation Example 1, 55 parts by weight of the aromatic vinyl-vinyl cyanide non-crosslinked copolymer (83SF, purchased from LG Chem), 25 parts by weight of the graft copolymer (DP270M, purchased from LG Chem), and 0.1 part by weight of a heat stabilizer (IRGANOX 1010, purchased from BASF SE).

[0133] Example 2

[0134] A resin composition was prepared in the same manner as in Example 1, except that 20 parts by weight of the aromatic vinyl-vinyl cyanide crosslinked copolymer prepared in Preparation Example 2 was used instead of 20 parts by weight of the aromatic vinyl-vinyl cyanide crosslinked copolymer prepared in Preparation Example 1.

[0135] Example 3

[0136] A resin composition was prepared in the same manner as in Example 1, except that 20 parts by weight of the aromatic vinyl-vinyl cyanide crosslinked copolymer prepared in Preparation Example 3 was used instead of 20 parts by weight of the aromatic vinyl-vinyl cyanide crosslinked copolymer prepared in Preparation Example 1.

[0137] Example 4

[0138] A resin composition was prepared in the same manner as in Example 1, except that 20 parts by weight of the aromatic vinyl-vinyl cyanide crosslinked copolymer prepared in Preparation Example 4 was used instead of 20 parts by weight of the aromatic vinyl-vinyl cyanide crosslinked copolymer prepared in Preparation Example 1.

[0139] Example 5

[0140] A resin composition was prepared in the same manner as in Example 1, except that 20 parts by weight of the aromatic vinyl-vinyl cyanide crosslinked copolymer prepared in Preparation Example 5 was used instead of 20 parts by weight of the aromatic vinyl-vinyl cyanide crosslinked copolymer prepared in Preparation Example 1.

[0141] Example 6

[0142] A resin composition was prepared by mixing 30 parts by weight of the aromatic vinyl-vinyl cyanide crosslinked copolymer prepared in Preparation Example 1, 45 parts by weight of an aromatic vinyl-vinyl cyanide non-crosslinked copolymer (83SF, purchased from LG Chem), 25 parts by weight of a graft copolymer (DP270M, purchased from LG Chem), and 0.1 part by weight of a heat stabilizer (IRGANOX 1010, purchased from BASF SE).

[0143] Example 7

[0144] A resin composition was prepared by mixing 10 parts by weight of the aromatic vinyl-vinyl cyanide crosslinked copolymer prepared in Preparation Example 1, 65 parts by weight of an aromatic vinyl-vinyl cyanide non-crosslinked copolymer (83SF, purchased from LG Chem), 25 parts by weight of a graft copolymer (DP270M, purchased from LG Chem), and 0.1 part by weight of a heat stabilizer (IRGANOX 1010, purchased from BASF SE).

[0145] Example 8

[0146] A resin composition was prepared by mixing 20 parts by weight of the aromatic vinyl-vinyl cyanide crosslinked copolymer prepared in Preparation Example 1, 55 parts by weight of the aromatic vinyl-vinyl cyanide non-crosslinked copolymer (83SF, purchased from LG Chem), 25 parts by weight of the graft copolymer prepared based on an acrylic polymer (SA927, purchased from LG Chem), and 0.1 part by weight of a heat stabilizer (IRGANOX 1010, purchased from BASF SE).

[0147] Comparative Example 1

[0148] A resin composition was prepared in the same manner as in Example 1, except that 20 parts by weight of the aromatic vinyl-vinyl cyanide crosslinked copolymer prepared in Comparative Preparation Example 1 was used instead of 20 parts by weight of the aromatic vinyl-vinyl cyanide crosslinked copolymer prepared in Preparation Example 1.

[0149] Comparative Example 2

[0150] A resin composition was prepared in the same manner as in Example 1, except that 20 parts by weight of the aromatic vinyl-vinyl cyanide crosslinked copolymer prepared in Comparative Preparation Example 2 was used instead of 20 parts by weight of the aromatic vinyl-vinyl cyanide crosslinked copolymer prepared in Preparation Example 1.

[0151] Comparative Example 3

[0152] A resin composition was prepared in the same manner as in Example 1, except that 20 parts by weight of the aromatic vinyl-vinyl cyanide crosslinked copolymer (B-MAT, purchased from GE) was used instead of 20 parts by weight of the aromatic vinyl-vinyl cyanide crosslinked copolymer prepared in Preparation Example 1.

[0153] Comparative Example 4

[0154] A resin composition was prepared by mixing 75 parts by weight of the aromatic vinyl-vinyl cyanide non-crosslinked copolymer (83SF, purchased from LG Chem), 25 parts by weight of the graft copolymer (DP270M, purchased from LG Chem), and 0.1 part by weight of a heat stabilizer (IRGANOX 1010, purchased from BASF SE).

[0155] Test Example 1

[0156] The resin compositions prepared in Examples 1 to 8 and Comparative Examples 1 to 4 were put into a twin-screw extruder, mixed and extruded at 200 °C to prepare pellets. After injecting the pellets at 220 °C, the melt index, glossiness, and coefficient of variation of light reflection were measured using the following methods, and the results are shown in Table 1 below.

[0157] (1) Glossiness: According to ASTM D523, the 60° glossiness was measured using a glossmeter (VG7000, purchased from NIPPON DENSHOKU).

[0158] (2) Coefficient of variation of light reflection: Obtained using Phyton and the following method.

[0159] 1) Sample imaging: Using a digital single-lens reflex camera (Canon 750D) and a 200 mm × 200 mm white LED (collimated backlight LTS-3PFT), the prepared sample was photographed and imaged when the distance between the camera and the sample was set to 40 cm, the distance between the sample and the light was set to 100 cm, and the angle was 90°.

[0160] 2) Grayscale conversion of the sample image: The sample image was converted to grayscale (0 to 255) using the OpenCV library. Gray values were assigned to each pixel in the sample image and used as the luminous intensity.

[0161] 3) Image reconstruction: The image was reconstructed by dividing the image into 200 μm × 200 μm grids and averaging the luminous intensity values (gray values) of the pixels in each grid. Each grid had an average luminous intensity value.

[0162] 4) Luminous intensity correction: The target grid was set as Region 1, the 8 grids adjacent to Region 1 were set as Region 2, and the 16 grids adjacent to Region 2 were set as Region 3. After assigning 1, -0.0625, and -0.03125 as correction factors to Region 1, Region 2, and Region 3 respectively, the corrected luminous intensity value of the target grid was derived using Equation 2 below.

[0163] [Equation 2]

[0164]

[0165] In Equation 2, L is the corrected luminous intensity value of the target grid, L 1 is the luminous intensity of the grid in Region 1, L 2 1 、L 2 2 、L 2 3 、…、L 2 8 are the respective luminous intensities of the 8 grids in Region 2, L 3 1 、L 3 2 、L 3 3 、…、L 3 16are the respective luminous intensities of the 16 meshes in Region 3.

[0166] 5) Mean value and standard deviation: After obtaining the mean value and standard deviation from the corrected luminous intensity values of each mesh, the coefficient of variation of light reflection is obtained by substituting the mean value and standard deviation of the luminous intensity into Equation 1.

[0167] [Equation 1]

[0168] C LR = D L / M L

[0169] C LR is the coefficient of variation of light reflection, D L is the standard deviation of the luminous intensity, M L is the average luminous intensity.

[0170] (3) Melt flow index (g / 10 min): The melt flow index is measured according to ASTM D1238 under the conditions of 220 °C and 10 kg.

[0171] [Table 1]

[0172]

[0173]

[0174] Referring to Table 1, it can be seen that Examples 1 to 8 using the crosslinked copolymers of Preparation Examples 1 to 5 have low gloss and a low coefficient of variation of light reflection.

[0175] On the other hand, the copolymers of Comparative Preparation Examples 1 and 2 polymerized by adding a crosslinking agent only at the beginning have a low yield regardless of the amount of the crosslinking agent added, and it can be confirmed that Comparative Examples 1 and 2 using these copolymers have a high coefficient of variation of light reflection and high gloss compared with the Examples, and Comparative Example 3 using a commercially available crosslinked copolymer prepared by reactive extrusion has a relatively high gloss and a high coefficient of variation of light reflectance compared with the Examples. Comparative Example 4 has a significantly high gloss due to the absence of a crosslinked copolymer.

[0176] Based on the above results, when the crosslinked copolymer prepared by the method according to the present invention is used in a resin composition, a matte product with a smooth surface can be sufficiently prepared by injection, and since this process does not require any specific treatment of the injection mold, the reproducibility is high, and it is confirmed that the method is suitable for mass production.

Claims

1. A resin composition comprising an aromatic vinyl-vinyl cyanide crosslinked copolymer, wherein, the 60° gloss measured using a gloss meter according to ASTM D523 is 25 or less, and the coefficient of variation of light reflection calculated by the following Equation 1 is 2.0 or less: [Equation 1] C LR = D L / M L Among them, C LR is the coefficient of variation of light reflection, D L is the standard deviation of the luminous intensity, M L is the average luminous intensity.

2. The resin composition according to claim 1, wherein, based on 100 parts by weight of the resin composition, the content of the aromatic vinyl-vinyl cyanide crosslinked copolymer is 1 to 30 parts by weight.

3. The resin composition according to claim 1, wherein, based on 100 parts by weight of the resin composition, the content of the aromatic vinyl-vinyl cyanide crosslinked copolymer is 3 to 20 parts by weight.

4. The resin composition according to claim 1, wherein, the gloss is 20 or less.

5. The resin composition according to claim 1, wherein, the coefficient of variation of light reflection is 1.5 or less.

6. The resin composition according to claim 1, wherein, the aromatic vinyl-vinyl cyanide crosslinked copolymer includes a crosslinked portion containing organosilicon compound units and polyene compound units, aromatic vinyl monomer units, and vinyl cyanide monomer units.

7. The resin composition according to claim 1, wherein, the resin composition further comprises one or more copolymers selected from aromatic vinyl-vinyl cyanide non-crosslinked copolymers and graft copolymers.

8. The resin composition according to claim 7, based on 100 parts by weight of the resin composition, the resin composition comprises 5 to 35 parts by weight of the aromatic vinyl-vinyl cyanide crosslinked copolymer, 45 to 65 parts by weight of the aromatic vinyl-vinyl cyanide non-crosslinked copolymer, and 20 to 30 parts by weight of the graft copolymer.

9. The resin composition according to claim 7, wherein, the aromatic vinyl-vinyl cyanide non-crosslinked copolymer includes aromatic vinyl monomer units and vinyl cyanide monomer units, and the graft copolymer includes a conjugated diene polymer, aromatic vinyl monomer units, and vinyl cyanide monomer units.

10. A molded article comprising the resin composition according to claim 1.

11. The molded article according to claim 10, wherein the molded article is injection molded.

Images