Alpha-methylstyrene composition as well as preparation method and application thereof

Abstract

The invention relates to the technical field of SAN resin modification, in particular to an alpha-methylstyrene composition and a preparation method and application thereof.According to the alpha-methylstyrene composition, the content of a compound shown in the formula (I) is controlled within the range of 10-100 ppm, and the content of the compound shown in the formula (I) is controlled within the range of 10-100 ppm. The SAN resin prepared from the low-yellowness-index SAN resin as a raw material has the advantages of low yellowness index and high heat resistance.

Description

Technical Field

[0001] This invention relates to the field of SAN resin modification technology, specifically to an α-methylstyrene composition, its preparation method, and its application. Background Technology

[0002] Styrene-acrylonitrile copolymer (SAN resin) is an important type of thermoplastic polymer material that combines the excellent processing flow and good mechanical strength of styrene resin with the chemical resistance provided by the acrylonitrile component. It is widely used in electronic and electrical appliance housings, automotive interior parts, food packaging containers, and optical lenses. Furthermore, SAN resin can also be used as a base material to co-extrude with polybutadiene rubber particles to prepare ABS resin. ABS resin possesses excellent physical and mechanical properties, excellent low-temperature impact resistance, electrical properties, abrasion resistance, dimensional stability, chemical resistance, dyeability, and ease of molding and machining. It is widely used in electronics and large appliances, small appliances, transportation (such as dashboards and wheel covers), and light industry (such as bags, toys, and sheet materials).

[0003] As downstream applications increasingly demand higher material performance, especially in high-temperature environments such as electronic component packaging and automotive engine peripheral parts, higher standards are being set for the heat resistance of SAN and ABS resins. The heat distortion temperature of ordinary SAN resin is typically between 80-100℃, which is insufficient to meet the heat resistance requirements in these scenarios. To impart higher heat resistance to SAN resin, the introduction of α-methylstyrene (AMS) is generally employed.

[0004] However, in actual production and application, it has been found that heat-resistant SAN resins prepared by introducing α-methylstyrene generally have a high yellowness index (YI). In addition, the molded products tend to show obvious yellow hues during storage at room temperature or high-temperature processing (such as injection molding and extrusion). Especially for transparent or light-colored products, the yellowing phenomenon will seriously affect the appearance quality and visual effect of the product, limiting its application in high-end transparent parts (such as optical shells and medical packaging).

[0005] In the existing technology, the improvement solutions for the yellowing problem of heat-resistant SAN resin mostly focus on the post-treatment of the resin after copolymerization (such as adding antioxidants and ultraviolet absorbers) or the optimization of copolymerization process parameters (such as adjusting the reaction temperature and the type of initiator).

[0006] These solutions can only delay the subsequent yellowing process of the resin to a certain extent, and cannot eliminate the influence of color-developing molecules on the yellowness index of the resin from the root, resulting in the resin yellowness index remaining high. Summary of the Invention

[0007] This invention provides an α-methylstyrene composition, its preparation method, and its application to solve the problem of high yellowness index in SAN resin.

[0008] Therefore, this application provides an α-methylstyrene composition comprising α-methylstyrene and 10-100 ppm of a compound represented by formula (I) below;

[0009] Formula (I); R1 is selected from C4-C10 hydrocarbon groups containing carbon-carbon double bonds.

[0010] In some embodiments, the compound represented by formula (I) is selected from one or more of 2,4-diphenyl-4-methyl-2-pentene, 2,4-diphenyl-4-methyl-1-pentene, and 2,5-diphenyl-1-hexene; and / or, the content of α-methylstyrene in the α-methylstyrene composition is ≥99.5%.

[0011] On the other hand, this application also provides a method for preparing the above-described α-methylstyrene composition, the preparation method comprising either method one or method two: Method 1: An α-methylstyrene composition was prepared by mixing α-methylstyrene with the compound shown in formula (I); Method 2: A solution containing an α-methylstyrene composition is obtained by separating the light components generated during the polymerization reaction of α-methylstyrene and acrylonitrile monomers to prepare SAN resin; or, a solution containing an α-methylstyrene composition is obtained by separating the light components generated during the polymerization reaction of the α-methylstyrene composition and acrylonitrile monomers to prepare SAN resin.

[0012] In some embodiments, the solution containing the α-methylstyrene composition further includes acrylonitrile monomers and solvents; Optionally, the mass content of acrylonitrile monomers in the solution containing the α-methylstyrene composition is 10-40%; Optionally, the solvent content in the solution containing the α-methylstyrene composition is 10-30% by mass; Optionally, the solvent is one or more selected from benzene, toluene, xylene, and ethylbenzene; Optionally, the acrylonitrile monomer is selected from one or more of acrylonitrile, methacrylonitrile, phenylacrylonitrile, or α-chloroacrylonitrile.

[0013] In some embodiments, in method two, the light components are separated by vacuum distillation, with the distillation column top temperature at 120~130℃, the bottom temperature at 180~200℃, and the top pressure at 40~60kPa.

[0014] On the other hand, this application also provides a SAN resin, wherein the raw materials for preparing the SAN resin include the α-methylstyrene composition described above or the α-methylstyrene composition prepared by any of the preparation methods described above, and further include acrylonitrile monomers; Optionally, the acrylonitrile monomer is one or more selected from acrylonitrile, methacrylonitrile, phenylacrylonitrile, or α-chloroacrylonitrile; Optionally, the SAN resin has a weight-average molecular weight of 85,000-100,000 g / mol and a molecular weight distribution of 1.9-2.2. Preferably, the mass content a of oligomers with a molecular weight greater than or equal to 200 and less than or equal to 500 in the SAN resin is 1000-5000 ppm, more preferably 1500-3000 ppm; the mass content b of oligomers with a molecular weight greater than 500 and less than or equal to 1000 in the SAN resin is 50-800 ppm, more preferably 100-600 ppm.

[0015] On the other hand, this application also provides a method for preparing the SAN resin described above, including one of method one, method two, and method three; Method 1 includes the following steps: A feed liquid containing α-methylstyrene, acrylonitrile monomers, solvents, and an initiator is continuously fed into a reactor, where a polymerization reaction occurs. The reaction product is then treated to remove light components, yielding SAN resin and light components. After separating the light components, a solution containing the α-methylstyrene composition is obtained. The solution containing the α-methylstyrene composition is continuously refluxed back into the reactor. The second method includes the following steps: (1) Polymerization reaction process: The α-methylstyrene composition is polymerized with acrylonitrile monomers in the presence of solvent and initiator; (2) Separation process: The reaction product obtained in step (1) is subjected to a light component removal process to obtain SAN resin; Method 3 includes the following steps: A feed liquid containing an α-methylstyrene composition, an acrylonitrile monomer, a solvent, and an initiator is continuously fed into a reactor, where a polymerization reaction occurs. The reaction product is then treated to remove light components, yielding SAN resin and light components. After separating the light components, a solution containing the α-methylstyrene composition is obtained. The solution containing the α-methylstyrene composition is continuously refluxed back into the reactor.

[0016] In some embodiments, in method one, method two, or method three, the temperature of the polymerization reaction is 110~130°C; And / or, in method one, method two, or method three, the solvent is one or more of benzene, toluene, xylene, and ethylbenzene; And / or, in method one, method two, or method three, the initiator is one or more of an organic peroxide initiator or an azo initiator; And / or, in method one, the mass ratio of α-methylstyrene to solvent is 60~80:5~20; And / or, in Method 1, the mass ratio of α-methylstyrene to acrylonitrile monomer is 60~80:20~40; And / or, in method two or method three, the mass ratio of the α-methylstyrene composition to the solvent is 60~80:5~20; And / or, in Method 2, the mass ratio of the α-methylstyrene composition to the acrylonitrile monomer is 60~80:20~40; And / or, in method three, the mass ratio of the α-methylstyrene composition to the acrylonitrile monomer is 60-80:20-40; And / or, in Method 1, the mass ratio of the initiator to the total mass of α-methylstyrene and acrylonitrile monomers is 0.05~0.2:80~120; And / or, in method two or method three, the mass ratio of the initiator to the total mass of the α-methylstyrene composition and the acrylonitrile monomer is 0.05~0.2:80~120; And / or, in Method 1, Method 2 or Method 3, the temperature for removing light components is 205~230℃, the absolute pressure is 1~15kPa, and the time is 1~15min; And / or, in method one or method three, the mass ratio of the solution containing the α-methylstyrene composition to the raw material liquid is 40-50:50-60.

[0017] On the other hand, this application also provides a resin composition comprising the SAN resin described above or the SAN resin prepared by the above preparation method, and further comprising polybutadiene rubber particles and / or ABS resin; Optionally, other adjuvants may also be included; Optionally, the mass ratio of the SAN resin to the polybutadiene rubber particles and / or ABS resin is 60~80:20~40.

[0018] On the other hand, this application also provides a molded article, which is formed by molding the SAN resin or the SAN resin obtained by the preparation method or a resin composition including the SAN resin; optionally, the molded article is an automotive interior component, an electronic or electrical housing, an optical lens, a food packaging container, or a tubular device.

[0019] The technical solution of this invention has the following advantages: 1. The α-methylstyrene composition provided by the present invention, wherein the content of the compound shown in formula (I) is controlled in the range of 10-100 ppm, and the SAN resin prepared from it as a raw material or the resin composition made from the SAN resin with polybutadiene rubber particles and / or ABS resin has a significantly reduced yellowness index, thereby improving the heat resistance of the resin.

[0020] 2. The SAN resin provided by the present invention has an oligomer content (a) of 50-800 ppm with a number average molecular weight greater than or equal to 200 and less than or equal to 500, and an oligomer content (a) of 1000-5000 ppm with a number average molecular weight greater than 500 and less than or equal to 1000. By limiting a and b to the above ranges, the yellowness index of the SAN resin or the resin composition made from the SAN resin and polybutadiene rubber particles and / or ABS resin can be further reduced, and it has excellent processing performance.

[0021] 3. The heat-resistant SAN resin prepared by this invention has good color, high heat resistance and good thermal stability, and can be applied to transparent or light-colored products, with excellent product appearance quality and visual effect, expanding its application in high-end transparent components (such as optical shells and medical packaging). Attached Figure Description

[0022] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0023] Figure 1 This is a process flow diagram of the SAN resin provided in a specific embodiment of this application; 1. First reactor; 2. Second reactor; 3. First devourer; 4. Second devourer; 5. Storage tank; 6. Distillation column. Detailed Implementation The following embodiments are provided to better understand the present invention, but the following embodiments do not constitute a limitation on the content and scope of protection of the present invention. Any product that is the same as or similar to the present invention, derived by any person under the guidance of the present invention or by combining the features of the present invention with other prior art, falls within the scope of protection of the present invention.

[0024] Unless otherwise specified, the experimental steps or conditions in the examples were performed in accordance with conventional experimental procedures and conditions in the art. Reagents or instruments whose manufacturers are not specified are all commercially available products.

[0025] I. Main Raw Material Sources The main raw material information involved in this invention is shown in Table 1: Table 1. Information on Main Raw Materials

[0026] II. Main Testing Methods The main testing methods involved in this invention are as follows: (1) The contents of 2,4-diphenyl-4-methyl-2-pentene, 2,4-diphenyl-4-methyl-1-pentene, 2,5-diphenyl-1-hexene, α-methylstyrene, acrylonitrile and toluene in the solution containing the α-methylstyrene composition were determined by gas chromatography.

[0027] Instrument model: Agilent 7890B GC-FID; Column: HP-5 (stationary phase: 5% phenyl-polymethylsiloxane), dimensions: 30 m × 0.25 mm × 0.25 μm; Temperature program: initial temperature 50℃, increase to 80℃ at 5℃ / min, then increase to 310℃ at 15℃ / min, hold for 12 min; Injector temperature: 310℃; FID detector temperature: 320℃; Split injection, split ratio 10:1; Injection volume: 1.0 μL; Carrier gas flow rate (nitrogen): 1 mL / min; Hydrogen flow rate: 30 mL / min; Air flow rate: 400 mL / min; Make-up gas flow rate: 25 mL / min.

[0028] (2) Glass transition temperature (Tg): 1g of SAN resin sample was dissolved in 10g of tetrahydrofuran, flocculated with 50g of ethanol, dried in a vacuum oven at 80℃ under negative pressure for 30min, and then tested with a Swiss METTLER instrument. The unit is °C. (3) Weight-average molecular weight (Mw) and molecular weight distribution (PDI): SAN resin was tested using a Shimadzu 20AD gel permeation chromatograph (GPC) from Japan, in g / mol. (4) Determination of oligomer content: 100 mg of sample was dissolved in 20 ml of tetrahydrofuran and the oligomer content was determined using a Shimadzu 20AD gel permeation chromatograph (GPC).

[0029] (5) Monomer conversion test: Weigh 1g of the reaction solution and place it in tin foil (weigh the tin foil beforehand). Place it in a vacuum oven at 220℃, control the absolute pressure <1KPa, and vacuum for 0.5h. After evacuation, remove it and cool it to room temperature. Weigh the dry resin. The monomer conversion rate can be calculated using the following formula: Monomer conversion rate = dry resin weight / (reaction solution mass × monomer feed mass fraction of total feed) × 100%. Monomer feed mass fraction of total feed = (mass of α-methylstyrene + mass of acrylonitrile / total mass of feed solution).

[0030] (6) The removal rate of light components in the devolatilization stage can be calculated by the following formula: mass flow rate of the condensate flowing out of the devolatilizer after the light components are condensed / feed flow rate of the devolatilizer × (1 - monomer conversion rate) × 100%.

[0031] Example 1 This embodiment provides a method for preparing an α-methylstyrene composition and SAN resin. The process flow is described in [link to process flow chart]. Figure 1 As shown, it includes the following steps: α-Methylstyrene (AMS) was mixed with acrylonitrile (AN), toluene, and initiator 1,1-di-tert-butylperoxide-3,3,5-trimethylcyclohexane (TMCH) in a mass ratio of 75:25:5:0.1 to obtain a feed solution. The feed solution was continuously pumped into a first reactor 1 with a volume of 500L at a feed rate of 100kg / h. The temperature of the first reactor was controlled at 120℃, and the monomer conversion rate of the reaction solution in the reactor was controlled at 30%±5%.

[0032] Simultaneously, the slurry from the first reactor is continuously pumped into the second reactor 2 with a volume of 500L at a feed rate of 100kg / h. The temperature of the second reactor is controlled at 120℃, and the monomer conversion rate of the reaction liquid in the reactor is controlled at 60%±5%.

[0033] The reaction liquid from the second reactor is fed into the first devolatilizer 3. The melt temperature inside the devolatilizer is controlled at 160℃, the pressure at 50kPa, and the devolatilization time at 10min, removing 75% of the light components (i.e., the light component removal rate is 75%).

[0034] The polymer melt after devolatilization in the first devolatilizer is fed into the second devolatilizer 4 for a second devolatilization treatment. The melt temperature in the second devolatilizer is controlled at 220°C, the pressure is 2 kPa, and the devolatilization time is 10 min. 25% of the light components are removed (i.e., the light component removal rate is 25%). The devolatilized polymer melt is then water-cooled and pelletized to obtain granular SAN resin products.

[0035] The condensate obtained after condensing the light components removed from the first and second devolatilizers is mixed in storage tank 5 and then fed into distillation column 6 for vacuum distillation. The operating conditions of the distillation column are as follows: bottom temperature 185℃; top temperature 125℃; top pressure 45kPa; top reflux ratio 2.05:1. A solution containing the α-methylstyrene composition (denoted as reflux liquid, the composition of which is shown in Tables 2 and 3) is collected from the top of the distillation column and continuously introduced into the feed stream of the first reactor at a feed rate of 40kg / h. The solution containing the α-methylstyrene composition is mixed with the feed liquid before the feed inlet of the first reactor and then continuously pumped into the first reactor at a feed rate of 100kg / h.

[0036] The total content of the α-methylstyrene composition in the reflux liquid is denoted as f; the content of α-methylstyrene in the α-methylstyrene composition is denoted as w0; the content of 2,4-diphenyl-4-methyl-2-pentene in the α-methylstyrene composition is denoted as w1; the content of 2,4-diphenyl-4-methyl-1-pentene in the α-methylstyrene composition is denoted as w2; the content of 2,5-diphenyl-1-hexene in the α-methylstyrene composition is denoted as w3; the content of acrylonitrile in the reflux liquid is denoted as w4; and the content of toluene in the reflux liquid is denoted as w5.

[0037] The mass content of oligomers with a molecular weight greater than or equal to 200 and less than or equal to 500 in SAN resin is denoted as 'a'; the mass content of oligomers with a molecular weight greater than 500 and less than or equal to 1000 is denoted as 'b'. The parameters are shown in Table 3. The weight-average molecular weight, molecular weight distribution, and glass transition temperature of SAN resin are shown in Table 4.

[0038] Example 2 This embodiment provides a method for preparing an α-methylstyrene composition and SAN resin, which is basically the same as that in Example 1, except that azobisisobutyronitrile (AIBN) is used instead of 1,1-di-tert-butylperoxide-3,3,5-trimethylcyclohexane (TMCH).

[0039] Example 3 This embodiment provides a method for preparing an α-methylstyrene composition and SAN resin, which is basically the same as that in Example 1, except that the mass ratio of the raw materials is different. In this embodiment, α-methylstyrene is mixed with acrylonitrile, toluene and initiator 1,1-di-tert-butylperoxide-3,3,5-trimethylcyclohexane in a mass ratio of 70:30:10:0.1.

[0040] Example 4 This embodiment provides a method for preparing an α-methylstyrene composition and SAN resin, which is basically the same as that in Example 1, except that the raw material composition and mass ratio are different. In this embodiment, α-methylstyrene is mixed with acrylonitrile, toluene and initiator 1,1-di-tert-butylperoxide-3,3,5-trimethylcyclohexane in a mass ratio of 65:35:10:0.15.

[0041] Example 5 This embodiment provides a method for preparing an α-methylstyrene composition and SAN resin, which is basically the same as that in Example 1, except that the raw material composition and mass ratio are different. In this embodiment, α-methylstyrene is mixed with acrylonitrile, toluene and initiator 1,1-di-tert-butylperoxide-3,3,5-trimethylcyclohexane in a mass ratio of 68:32:10:0.2.

[0042] Example 6 This embodiment provides a method for preparing an α-methylstyrene composition and SAN resin, which is basically the same as in Example 1. The pressure at the top of the distillation column is adjusted to 60 kPa during the vacuum distillation process of the light component, so that the content of the compound shown in formula (I) in the α-methylstyrene composition is different.

[0043] Example 7 This embodiment provides a method for preparing an α-methylstyrene composition and SAN resin, which is basically the same as in Example 1. The pressure at the top of the distillation column is adjusted to 40 kPa during the vacuum distillation process of the light component, so that the content of the compound shown in formula (I) in the α-methylstyrene composition is different.

[0044] Example 8 This embodiment provides an α-methylstyrene composition comprising 90 ppm of 2,5-diphenyl-1-hexene, with the balance being α-methylstyrene.

[0045] The preparation method is as follows: 2,5-diphenyl-1-hexene is mixed with α-methylstyrene to obtain the product.

[0046] This embodiment also provides a method for preparing SAN resin, including the following steps: 75 kg of α-methylstyrene composition was mixed with 25 kg of acrylonitrile, 5 kg of toluene and 0.1 kg of initiator 1,1-di-tert-butylperoxide-3,3,5-trimethylcyclohexane (TMCH) in a reactor, and the reactor temperature was controlled at 120 °C for 4 h.

[0047] The reaction liquid from the reactor is fed into a devolatilizer to remove light components. The devolatilized polymer melt is then water-cooled and pelletized to obtain granular SAN resin products.

[0048] In this embodiment, the content of α-methylstyrene in the raw material α-methylstyrene composition is denoted as w0; the content of 2,5-diphenyl-1-hexene in the α-methylstyrene composition is denoted as w3, as shown in Table 2. The mass content of oligomers with a molecular weight greater than or equal to 200 and less than or equal to 500 in the SAN resin is denoted as a; the mass content of oligomers with a molecular weight greater than 500 and less than or equal to 1000 is denoted as b, and the parameters are shown in Table 3.

[0049] Example 9 The only difference from Example 1 is that, in the preparation of the raw material solution, the same mass of α-methylstyrene composition is used instead of the α-methylstyrene used in Example 1. The α-methylstyrene composition comprises 15 ppm of 2,4-diphenyl-4-methyl-1-pentene, with the balance being α-methylstyrene. Its preparation method is as follows: 2,4-diphenyl-4-methyl-1-pentene is mixed with α-methylstyrene to obtain the solution.

[0050] Example 10 This embodiment provides a method for preparing an α-methylstyrene composition and SAN resin, which is basically the same as in Example 1. In the second devolatilization process, the temperature inside the second devolatilizer is adjusted to 230°C, so that a and b are different.

[0051] Example 11 This embodiment provides a method for preparing an α-methylstyrene composition and SAN resin, which is basically the same as in Example 1. In the second devolatilization process, the pressure inside the second devolatilizer is adjusted to 10 kPa, so that a and b are different.

[0052] Comparative Example 1 This comparative example provides a method for preparing an α-methylstyrene composition and SAN resin, which is basically the same as that in Example 1, except that the light components extracted from the first devolatilizer and the second devolatilizer are mixed and then directly introduced into the feed stream of the first reactor without vacuum distillation.

[0053] Comparative Example 2 This comparative example provides a method for preparing an α-methylstyrene composition and SAN resin, which is basically the same as in Example 1. The pressure at the top of the distillation column during the vacuum distillation of the light component is adjusted to 80 kPa, so that the content of the compound represented by formula (I) in the α-methylstyrene composition is different.

[0054] Comparative Example 3 This comparative example provides a method for preparing an α-methylstyrene composition and SAN resin, which is basically the same as in Example 1. The pressure at the top of the distillation column is adjusted to 20 kPa during the vacuum distillation of the light component, so that the content of the compound represented by formula (I) in the α-methylstyrene composition is different.

[0055] Comparative Example 4 This comparative example provides a method for preparing an α-methylstyrene composition and SAN resin, which is basically the same as in Example 1, except that 2,5-diphenyl-1-hexene is added to the solution containing the α-methylstyrene composition taken from the distillation column to increase the content of 2,5-diphenyl-1-hexene in the α-methylstyrene composition (i.e., the percentage of the total mass of 2,5-diphenyl-1-hexene and α-methylstyrene) to 106 ppm. The solution is then continuously introduced into the feed stream of the first reactor at a feed rate of 40 kg / h. The solution containing the α-methylstyrene composition and the feed liquid are mixed before the feed inlet of the first reactor and then continuously pumped into the first reactor at a feed rate of 100 kg / h.

[0056] Comparative Example 5 This comparative example provides an α-methylstyrene composition and a method for preparing SAN resin, which is basically the same as that in Example 8, except that the same mass of α-methylstyrene is used instead of the α-methylstyrene composition.

[0057] Comparative Example 6 This comparative example provides an α-methylstyrene composition and a method for preparing SAN resin, which is basically the same as that in Example 8, except that the composition of the α-methylstyrene composition is different. The α-methylstyrene composition in this comparative example includes 150 ppm of 2,5-diphenyl-1-hexene, with the balance being α-methylstyrene.

[0058] Table 2 Content of each substance

[0059] "—" indicates that the substance is not present or the level is below the detection limit of 1 ppm.

[0060] Table 3 Content of each substance and content of oligomers

[0061] "—" indicates that the substance is not present or the level is below the detection limit of 1 ppm.

[0062] Test Example 1 The heat distortion temperature (HDT) and thermal decomposition loss temperature (TGA) of the SAN resins prepared in the above embodiments and comparative examples were measured respectively. Each group of SAN resins was injection molded into 2mm thick optical sheets at 220℃, and the yellowness index (YI), transmittance, and haze of the optical sheets were tested. The test methods are as follows: Heat distortion temperature (HDT): Tested according to ISO 75-2:2013, SAN resin was injection molded into a sample with a length of 80 mm, a width of 10 mm and a thickness of 4 mm, and a bending stress of 1.8 MPa was applied along the thickness direction.

[0063] Yellowness Index (YI): The yellowness index of each optical film was measured using a Hunter Lab colorimeter. Transmittance and haze: The transmittance and haze of each group of optical films were tested using a haze meter in accordance with GB / T 2410-2008. Thermal decomposition loss temperature (TGA): The thermal decomposition temperature of each group of optical films when the material weight loss is 1% is measured by METTLER of Switzerland, in °C.

[0064] The results are shown in Table 4.

[0065] Table 4 Test results of SAN resin

[0066] Compared to the comparative examples, the SAN resins obtained in the embodiments of the present invention have a significantly reduced yellowness index, thereby improving the heat resistance of the resin. Furthermore, the processing performance of the SAN resin is also significantly improved.

[0067] Test Example 2 The SAN resins prepared in the above embodiments and comparative examples were used to prepare ABS resins, and their performance was evaluated, as follows: (1) Preparation method: 1.5 parts by weight of vinyl bis-stearamide (EBS), 0.1 parts by weight of antioxidant 1076, 0.2 parts by weight of antioxidant 618, and 0.2 parts by weight of magnesium stearate were added to a mixture of 30 parts by weight of ABS resin (HR181) and 70 parts by weight of the above-mentioned heat-resistant SAN resin and blended. The mixture was then used to prepare particulate resin at 220°C using a twin-screw extruder to obtain a resin composition. The resin composition was then injection molded at 220°C using an injection molding machine to obtain an optical film.

[0068] (2) Performance evaluation: The yellowness index (YI), unnotched impact strength of simply supported beam, and heat distortion temperature (HDT) of each group of ABS resins were measured. The specific test methods are as follows: Yellowness Index (YI): ABS resin was injection molded into 2mm samples at 220℃ using an injection molding machine, and the yellowness index of the samples was measured using a Hunter Lab colorimeter. Heat distortion temperature (HDT): Tested according to ISO 75-2:2013. ABS resin was injection molded into a sample with a length of 80 mm, a width of 10 mm, and a thickness of 4 mm, and a bending stress of 1.8 MPa was applied along the thickness direction.

[0069] Unnotched impact strength of simply supported beams: tested according to ASTM D256, unit KJ / m 2 The results are shown in Table 5. Table 5 Test results of the resin composition

[0070] Compared to the comparative examples, the ABS resins obtained in the embodiments of the present invention have a significantly reduced yellowness index, thereby improving the heat resistance of the resin. Furthermore, while maintaining a low yellowness index and high heat resistance, the processability of the ABS resin is also significantly improved.

[0071] Test Example 3 The melt flow rate (MFR) of the SAN resins prepared in Examples 1-11 and Comparative Examples 3 and 5 was measured, as was the melt volume flow rate (MVR) of the ABS resins prepared from the above-mentioned SAN resins in Test Example 2. The test methods are as follows: Melt Flow Index (MFR): MFR was tested at 220°C and under a 10kg load using a CEAST MF30 melt flow indexer according to ISO 1133-1:2022 standard, in g / 10min.

[0072] Melt volumetric flow rate (MVR): MVR was tested using a CEAST MF30 melt indexer at 220°C and under a 10kg load, according to ISO 1133-1:2022 standard. The unit is cm³. 3 / 10min.

[0073] Table 6 Test results of SAN resin and ABS resin

[0074] Compared to Comparative Examples 3 and 4, the SAN and ABS resins obtained in the embodiments of the present invention have significantly improved melt flow index and melt volume flow rate.

[0075] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. An α-methylstyrene composition, characterized in that, The α-methylstyrene composition comprises α-methylstyrene and 10-100 ppm of a compound of formula (I) below; Formula (I); R1 is selected from C4-C10 hydrocarbon groups containing carbon-carbon double bonds.

2. The α-methylstyrene composition according to claim 1, characterized in that, The compound represented by formula (I) is selected from one or more of 2,4-diphenyl-4-methyl-2-pentene, 2,4-diphenyl-4-methyl-1-pentene and 2,5-diphenyl-1-hexene; and / or, the content of α-methylstyrene in the α-methylstyrene composition is ≥99.5%.

3. A method for preparing the α-methylstyrene composition according to claim 1 or 2, characterized in that, The preparation method includes either method one or method two: Method 1: An α-methylstyrene composition was prepared by mixing α-methylstyrene with the compound shown in formula (I); Method 2: A solution containing an α-methylstyrene composition is obtained by separating the light components generated during the polymerization reaction of α-methylstyrene with acrylonitrile monomers to prepare SAN resin; or, a solution containing an α-methylstyrene composition is obtained by separating the light components generated during the polymerization reaction of the α-methylstyrene composition according to claim 1 or 2 with acrylonitrile monomers to prepare SAN resin.

4. The method for preparing the α-methylstyrene composition according to claim 3, characterized in that, The solution containing the α-methylstyrene composition also includes acrylonitrile monomers and solvents; Optionally, the mass content of acrylonitrile monomers in the solution containing the α-methylstyrene composition is 10-40%; Optionally, the solvent content in the solution containing the α-methylstyrene composition is 10-30% by mass; Optionally, the solvent is one or more selected from benzene, toluene, xylene, and ethylbenzene; Optionally, the acrylonitrile monomer is selected from one or more of acrylonitrile, methacrylonitrile, phenylacrylonitrile, or α-chloroacrylonitrile.

5. The method for preparing the α-methylstyrene composition according to claim 3, characterized in that, In Method 2, the light components are separated by vacuum distillation, with the top temperature of the distillation column being 120~130℃, the bottom temperature being 180~200℃, and the top pressure being 40~60kPa.

6. A SAN resin, characterized in that, The raw materials for preparing the SAN resin include the α-methylstyrene composition according to claim 1 or 2 or the α-methylstyrene composition prepared by any of the preparation methods according to claims 3-5, and also include acrylonitrile monomers; Optionally, the acrylonitrile monomer is one or more selected from acrylonitrile, methacrylonitrile, phenylacrylonitrile, or α-chloroacrylonitrile; Optionally, the SAN resin has a weight-average molecular weight of 85,000-100,000 g / mol and a molecular weight distribution of 1.9-2.

2. Preferably, the mass content (a) of oligomers with a molecular weight greater than or equal to 200 and less than or equal to 500 in the SAN resin is 1000-5000 ppm, more preferably 1500-3000 ppm; the mass content (b) of oligomers with a molecular weight greater than 500 and less than or equal to 1000 in the SAN resin is 50-800 ppm, more preferably 100-600 ppm.

7. A method for preparing the SAN resin according to claim 6, characterized in that, This includes one of the following methods: Method 1, Method 2, and Method 3. Method 1 includes the following steps: A feed liquid containing α-methylstyrene, acrylonitrile monomers, solvents, and an initiator is continuously fed into a reactor, where a polymerization reaction occurs. The reaction product is then treated to remove light components, yielding SAN resin and light components. After separating the light components, a solution containing the α-methylstyrene composition is obtained. The solution containing the α-methylstyrene composition is continuously refluxed back into the reactor. The second method includes the following steps: (1) Polymerization reaction process: The α-methylstyrene composition is polymerized with acrylonitrile monomers in the presence of solvent and initiator; (2) Separation process: The reaction product obtained in step (1) is subjected to a light component removal process to obtain SAN resin; Method 3 includes the following steps: A feed liquid containing an α-methylstyrene composition, an acrylonitrile monomer, a solvent, and an initiator is continuously fed into a reactor, where a polymerization reaction occurs. The reaction product is then treated to remove light components, yielding SAN resin and light components. After separating the light components, a solution containing the α-methylstyrene composition is obtained. The solution containing the α-methylstyrene composition is continuously refluxed back into the reactor.

8. The method for preparing SAN resin according to claim 7, characterized in that, In method one, method two, or method three, the polymerization reaction temperature is 110~130℃; And / or, in method one, method two, or method three, the solvent is one or more of benzene, toluene, xylene, and ethylbenzene; And / or, in method one, method two, or method three, the initiator is one or more of an organic peroxide initiator or an azo initiator; And / or, in method one, the mass ratio of α-methylstyrene to solvent is 60~80:5~20; And / or, in Method 1, the mass ratio of α-methylstyrene to acrylonitrile monomer is 60~80:20~40; And / or, in method two or method three, the mass ratio of the α-methylstyrene composition to the solvent is 60~80:5~20; And / or, in method two or method three, the mass ratio of the α-methylstyrene composition to the acrylonitrile monomer is 60~80:20~40; And / or, in Method 1, the mass ratio of the initiator to the total mass of α-methylstyrene and acrylonitrile monomers is 0.05~0.2:80~120; And / or, in method two or method three, the mass ratio of the initiator to the total mass of the α-methylstyrene composition and the acrylonitrile monomer is 0.05~0.2:80~120; And / or, in Method 1, Method 2 or Method 3, the temperature for removing light components is 205~230℃, the absolute pressure is 1~15kPa, and the time is 1~15min; And / or, in method one or method three, the mass ratio of the solution containing the α-methylstyrene composition to the raw material liquid is 40-50:50-60.

9. A resin composition, characterized in that, The resin includes the SAN resin of claim 6 or the SAN resin prepared by the preparation method of claim 7 or 8, and also includes polybutadiene rubber particles and / or ABS resin. Optional, other adjuvants may also be included; Optionally, the mass ratio of the SAN resin to the polybutadiene rubber particles and / or ABS resin is 60~80:20~40.

10. A molded article, characterized in that, It is formed by molding the SAN resin as described in claim 5 or 6, or the SAN resin prepared by the method described in claim 7 or 8, or the resin composition including the one described in claim 9; optionally, the molded article is an automotive interior component, an electronic or electrical housing, an optical lens, a food packaging container, or a tubular device.

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