Pure monomer resin with reduced ratio of low molecular weight oligomer and method of preparing the same

Abstract

The disclosed method is a method for producing a pure monomer resin with a reduced proportion of low molecular weight oligomers. The method includes the thermal polymerization of multiple monomers, including aromatic vinyl monomers, under catalyst-free conditions. The thermal polymerization step is a single-stage polymerization carried out in a single reactor, and the single reactor includes a continuous stirred tank reactor (CSTR).

Description

Technical Field

[0001] This invention relates to pure monomer resins and their preparation methods, and more particularly to pure monomer resins with reduced proportions of low molecular weight oligomers and their preparation methods. Prior Technology

[0002] Pure monomer resins (PMRs) have lower volatile organic compounds (VOCs), a lighter color (water white), and better thermal stability than other aromatic resins. Applications of pure monomer resins include additives, binders, and similar products in electric vehicle tires, and they are known as high value-added products.

[0003] The common method for producing commercially available pure monomer resins recently involves polymerization using catalysts such as Friedel-Crafts catalysts, Lewis acid catalysts, and similar substances. However, problems with this process include resin decomposition and contamination caused by residual halides from the catalyst. Furthermore, the unavoidable need for a neutralization process results in drawbacks such as wastewater generation.

[0004] Although the inventors of this invention have developed a method for polymerizing pure monomer resins under catalyst-free conditions, the problem lies in the generation of a large amount of low molecular weight oligomers as byproducts. These low molecular weight oligomers broaden the molecular weight distribution, causing deviations in product properties and lowering the softening point. As mentioned above, although low molecular weight oligomers must be removed to adjust the softening point, the removed oligomers are difficult to reintroduce as starting materials due to their low thermal polymerization reactivity, making it difficult to generate petroleum resin products from the removed oligomers. Therefore, even when producing pure monomer resins under catalyst-free conditions, it is still necessary to minimize the generation of low molecular weight oligomers as byproducts.

[0005] The background technology of this invention is disclosed in U.S. Patent No. 332332. Summary of the Invention

[0006] Technical issues

[0007] One of the subjects of this invention is to provide a pure monomeric resin and a method for preparing it, which minimizes the generation of low molecular weight oligomers such as byproducts.

[0008] Another subject of this invention is to provide a pure monomer resin with an increased softening point and a narrow molecular weight distribution, and a method for preparing the same.

[0009] Other aspects of this invention include providing a pure monomeric resin and its preparation method, which does not cause resin decomposition and contamination due to residual halides from the use of a catalyst, and has good physical properties.

[0010] Other subject matter of the present invention is to provide a pure monomeric resin and a method for preparing it, which does not require a separation process to remove the catalyst and therefore does not generate wastewater in the neutralization process of the polymer resin.

[0011] Other aspects of the present invention provide pure monomer resins and methods for their preparation, which can reduce catalyst costs and process costs associated with the use of catalysts, and can reduce process control points.

[0012] Other aspects of this invention provide pure monomeric resins and methods for their preparation, which allow for easy recovery, separation, and reuse of solvents and unreacted monomers.

[0013] Other aspects of this invention provide pure monomeric resins and methods for their preparation, which simplify property control.

[0014] Other aspects of this invention provide pure monomer resins and methods for their preparation, which can reduce the generation of volatile organic compounds and wastewater to ensure environmental protection.

[0015] The following embodiments of the present invention can achieve the above and other topics of the present invention.

[0016] Technical solution

[0017] 1. One aspect of the present invention relates to a method for preparing a pure monomer resin having a reduced proportion of low molecular weight oligomers. The method includes thermally polymerizing multiple monomers, including aromatic vinyl monomers, under catalyst-free conditions, wherein the thermal polymerization step is a single-stage polymerization carried out in a single reactor, and the single reactor is a continuous stirred tank reactor (CSTR).

[0018] 2. In Example 1, the monomer may include about 60 wt% to about 100 wt% of an aromatic vinyl monomer and about 0 to about 40 wt% of a comonomer, wherein the comonomer includes hydrogenated aromatic vinyl monomers, C4 to C10 olefin monomers, or combinations thereof.

[0019] 3. In Examples 1 and 2, the aromatic vinyl monomer may be selected from styrene, alkylstyrene, divinylbenzene, indene, alkylindene, vinyltoluene, mixed C9 oils, and derivatives thereof.

[0020] 4. In Examples 1 to 3, monomers and solvents are continuously fed into the reactor, with the monomer content being about 20 wt% to about 100 wt% and the solvent content being about 0 to about 80 wt%.

[0021] 5. In Examples 1 to 4, the temperature of the thermal polymerization step was about 150°C to about 300°C, and the pressure was about 5 bar to about 30 bar.

[0022] 6. In Examples 1 to 5, thermal polymerization is completed only through a single-stage polymerization in a continuous stirred tank reactor (CSTR), and the polymer obtained by thermal polymerization is not subjected to secondary thermal polymerization in a plug flow reactor.

[0023] 7. In Examples 1 to 5, the method may conform to Equation 1:

[0024] Formula 1

[0025] 100×[(A1-A2) / A1] ≥ 10,

[0026] Where A2 represents the ratio (%) of the area of ​​low molecular weight oligomers (residence time: 21.6 min to 24.1 min) to the total area of ​​the polymer in the GPC analysis of polymers obtained by single-stage thermal polymerization in a continuous stirred tank reactor, and A1 represents the ratio (%) of the area of ​​low molecular weight oligomers (residence time: 21.6 min to 24.1 min) to the total area of ​​the polymer in the GPC analysis of polymers obtained by two-stage thermal polymerization.

[0027] 8. Another aspect of the present invention relates to a pure monomer resin. The pure monomer resin can be prepared by the method described above, wherein its weight-average molecular weight (Mw) can be from about 300 g / mol to about 10,000 g / mol, its Z-average molecular weight (Mz) can be from about 1,000 g / mol to about 20,000 g / mol, its molecular weight distribution (e.g., polymer dispersibility index, PDI) is from about 1 to about 3, and its softening point is from about 0°C to about 150°C.

[0028] 9. In Example 8, the pure monomer resin may contain less than 100 ppm of residual halides.

[0029] 10. In Examples 8 and 9, the pure monomer resin may conform to Formula 2:

[0030] [Equation 2]

[0031] Io = OA×A2 < 35,

[0032] Where Io represents the low molecular weight oligomer index, OA represents the ratio (%) of the olefin region (4.0 ppm to 6.5 ppm region) to the total peak area calculated by integration in the 1H-NMR analysis, and A2 represents the ratio (%) of the area of ​​low molecular weight oligomers (residence time: 21.6 min to 24.1 min) to the total area of ​​the polymer in the GPC analysis of the polymer.

[0033] 11. In Examples 8 to 10, the ratio of the Z-average molecular weight to the weight-average molecular weight (Mz / Mw) of the pure monomer resin was less than about 2.5.

[0034] 12. In Examples 8 to 11, the aromatic component of the pure monomer resin may be about 40% to about 62.5%, the aliphatic component may be about 35% to about 60%, and the olefin component may be less than or equal to about 5%.

[0035] 13. Other aspects of the invention relate to bonding agents. Bonding agents may include the pure monomeric resins of Examples 8 to 12.

[0036] 14. Another aspect of the present invention relates to a method for reducing the proportion of low molecular weight oligomers in pure monomer resins. The method involves polymerizing aromatic vinyl monomers in a single reactor, wherein the single reactor is a continuous stirred tank reactor (CSTR).

[0037] 15. In Example 14, the method may conform to Equation 1:

[0038] [Formula 1]

[0039] 100 × [(A1-A2) / A1] ≥ 10,

[0040] Where A2 represents the ratio (%) of the area of ​​low molecular weight oligomers (residence time: 21.6 min to 24.1 min) to the total area of ​​the polymer in the GPC analysis of polymers obtained by single-stage thermal polymerization in a continuous stirred tank reactor, and A1 represents the ratio (%) of the area of ​​low molecular weight oligomers (residence time: 21.6 min to 24.1 min) to the total area of ​​the polymer in the GPC analysis of polymers obtained by two-stage thermal polymerization.

[0041] Technical effect

[0042] This invention provides a pure monomer resin that minimizes the generation of low molecular weight oligomers as byproducts and has an improved softening point and a narrow molecular weight distribution. The pure monomer resin does not decompose or pollute due to residual halides from the use of catalysts, and avoids wastewater generated during the neutralization of polymer resins by eliminating the need for catalyst removal separation processes. This reduces catalyst costs and process costs associated with catalyst use, and also reduces process control points. This process simplifies the recovery, separation, and reuse of solvents and unreacted monomers, simplifies the control of physical properties, and reduces the generation of volatile organic compounds and wastewater, thus being environmentally friendly. This invention also provides a method for preparing the above-mentioned pure monomer resin. Simple Explanation of the Diagram

[0043] Figure 1 is a diagram of the reaction process in one embodiment of the present invention. Figure 2 shows the gel permeation chromatography diagrams of Example 1 and Comparative Example 1. Figure 3 shows the gel permeation chromatography diagrams of Example 2 and Comparative Example 2. Implementation

[0044] The terms "comprising," "including," "having," and similar terms used herein are inclusive and indicate the presence of the stated structure, integer, step, operation, element, and / or component, but do not exclude the presence or addition of one or more other structures, integers, steps, operations, elements, components, and / or groups thereof. Furthermore, the singular forms "a," "an," and "the" may also include the plural forms unless otherwise explicitly stated.

[0045] Even if not explicitly stated, the ingredients here should be interpreted as including 5% or less.

[0046] The term "low molecular weight oligomers" here refers to aromatic vinyl oligomers with a weight average molecular weight of less than 700 g / mol.

[0047] Pure monomer resins (PMRs) include aromatic vinyl polymers. In one embodiment, pure monomer resins are prepared by thermal polymerization under catalyst-free conditions.

[0048] Figure 1 is a diagram of the reaction process in an embodiment of the present invention.

[0049] As shown in Figure 1, the preparation method of pure monomer resin may include a monomer solution thermal polymerization step in a single reactor. Here, under catalyst-free conditions, a single-stage thermal polymerization is carried out in a continuous stirred tank reactor (CSTR) 1.

[0050] In this invention, single-stage polymerization in a single reactor refers to polymerization completed in a single reactor without any secondary polymerization in subsequent reactors.

[0051] The continuous stirred tank reactor 1 can be selected from any typical reactor in this technical field without limitation, and can be used for polymerization reactions by continuous feeding and mixing of monomers. Thermal polymerization in the aforementioned continuous stirred tank reactor can maintain a consistent temperature during the reaction, reducing the possibility of localized hot spots and thus providing a narrow molecular weight distribution.

[0052] In one embodiment, the monomer and solvent are mixed and fed into a reactor, wherein the monomer content may be from about 20 wt% to 100 wt%, and the solvent content may be less than or equal to about 80 wt%.

[0053] Monomers may include about 60 wt% to about 100 wt% aromatic vinyl monomers, and, where appropriate, less than or equal to about 40 wt% comonomers.

[0054] Aromatic vinyl monomers may be selected from styrene, alkylstyrene, divinylbenzene, indene, alkylindene, vinyltoluene, mixed C9 oils, and derivatives thereof. For example, aromatic vinyl monomers may include about 30 wt% to 100 wt% of styrene monomers, and, where applicable, less than or equal to about 70 wt% of alkylstyrene monomers.

[0055] In one embodiment, a comonomer may be added together with the aromatic vinyl monomer. The comonomer may include a hydrogenated aromatic vinyl monomer (wherein hydroaddition to an aromatic ring), a C4 to C10 olefin monomer, or a combination thereof. In one embodiment, the comonomer may include vinylcyclohexane, vinylcyclohexene, isoprene, isoprene, ethylene, propylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 1-decene, 1-undecene, 1-dodecene, 1-tetradecene, 1-hexadecene, or a combination thereof. The comonomer may modify the resin structure to improve the compatibility of the polymer with the additives in the adhesive / bonding composition.

[0056] Solvents may include at least one of the following: benzene, toluene, xylene, and mixtures thereof.

[0057] In one embodiment, a free radical initiator may be further added to adjust the reactivity. The initiator may include cumene hydroperoxide, tert-butyl hydroperoxide, tert-butyl hydroperoxide benzoate, tert-butyl 4,4-di(tert-butylperoxy)valerate, or the like.

[0058] The temperature for thermal polymerization can be from about 150°C to about 300°C, for example from about 200°C to about 295°C, and particularly from about 250°C to about 290°C. Within this range, thermal polymerization exhibits good monomer conversion or polymerization rate, suppresses side reactions, and achieves consistent properties and a narrow molecular weight distribution.

[0059] The reaction pressure for thermal polymerization can be from about 5 bar to about 30 bar, for example, from about 10 bar to about 25 bar. Within this range, thermal polymerization exhibits good reaction stability and improves the reactivity of the monomer.

[0060] The thermal polymerization time can be from about 5 minutes to about 180 minutes, for example, from about 20 minutes to about 120 minutes, and particularly from about 30 minutes to about 60 minutes. Within this range, thermal polymerization can be carried out while suppressing side reactions and ensuring a narrow molecular weight distribution.

[0061] Because thermal polymerization is completed in a single stage in a continuous stirred tank reactor, the proportion of low molecular weight oligomers can be significantly reduced. In one embodiment, compared to pure monomer resins prepared by primary thermal polymerization in a continuous stirred tank reactor (CSTR) followed by secondary thermal polymerization in a plug flow reactor, the present invention can reduce the proportion of low molecular weight oligomers by about 10% or more, preferably by about 20% or more.

[0062] In one embodiment, the method of the present invention may conform to formula 1:

[0063] [Formula 1]

[0064] 100×[(A1-A2) / A1] ≥ 10,

[0065] Where A2 represents the ratio (%) of the area of ​​low molecular weight oligomers (residence time: 21.6 min to 24.1 min) to the total area of ​​the polymer in the GPC analysis of polymers obtained by single-stage thermal polymerization in a continuous stirred tank reactor, and A1 represents the ratio (%) of the area of ​​low molecular weight oligomers (residence time: 21.6 min to 24.1 min) to the total area of ​​the polymer in the GPC analysis of polymers obtained by two-stage thermal polymerization.

[0066] According to the present invention, the reaction temperature, monomer concentration, or reaction time can be controlled to adjust the proportion of low molecular weight oligomers, weight-average molecular weight, molecular weight distribution (PDI), or softening point of the pure monomer resin.

[0067] In one embodiment, the outlet port of the continuous stirred tank reactor (CSTR) may have a filter (not shown). The filter may be formed of one or more materials, such as metals, polymers, ceramics, and the like, and its pore size may be from about 100 nm to about 10 μm, preferably from about 100 nm to about 1 μm, and there are no particular limitations (as long as it can filter out foreign matter).

[0068] Solvent separation processes can be performed on polymerization products to recover pure monomer resin. In the solvent separation process, the solvent and some low-molecular-weight oligomers can be separated from the product. Thin-film evaporators can be used for the solvent separation process.

[0069] In one embodiment, a hydrogenation reaction may be further carried out. For example, the resulting pure monomer resin may be fed into a continuous hydrogenation reactor containing a hydrogenation catalyst for hydrogenation. The hydrogenation reaction may be carried out at a pressure of about 50 bar to about 150 bar and at a temperature of about 150°C to about 300°C, but is not limited thereto. Under these conditions, the molecular structure can be avoided from being damaged. The hydrogenation catalyst may be selected from any hydrogenation catalyst known in the art without any limitation. Specifically, the hydrogenation catalyst may include at least one selected from nickel, iron, copper, cobalt, molybdenum, palladium, rhodium, platinum, niobium, gold, rhenium, Raney nickel, and mixtures thereof. To improve reactivity, the molar ratio of the hydrogenation catalyst to 1 mole of petroleum resin monomer is about 0.001 to about 0.5, preferably about 0.05 to about 0.2, but is not limited thereto.

[0070] Because the present invention prepares pure monomer resin under catalyst-free conditions, the total polymer of the pure monomer resin contains less than about 100 ppm of residual halides, aromatic components of about 40% to about 62.5%, aliphatic components of about 35% to about 60%, and olefin components of less than or equal to about 5% (preferably less than or equal to about 2%, more preferably less than or equal to about 1.7%).

[0071] In one embodiment, when only aromatic vinyl monomers are polymerized, the low molecular weight oligomer index (Io) of the pure monomer resin is less than about 35, as shown in Formula 2:

[0072] [Equation 2]

[0073] Io = OA×A2 < 35,

[0074] Where Io represents the low molecular weight oligomer index, OA represents the ratio (%) of the olefin region (4.0 ppm to 6.5 ppm region) to the total peak area calculated by integration in the 1H-NMR analysis, and A2 represents the ratio (%) of the area of ​​low molecular weight oligomers (residence time: 21.6 min to 24.1 min) to the total area of ​​the polymer in the GPC analysis of the polymer.

[0075] In one embodiment, the low molecular weight oligomer index (Io) of the pure monomer resin is less than about 35, for example, from about 1 to about 24.5, more particularly from about 10 to about 20. Within this range, the pure monomer resin ensures consistent properties, suppresses the generation of volatile organic compounds, and has good adhesion when used as a binder.

[0076] The softening point of pure monomer resin is from about 0°C to about 150°C, for example, from about 70°C to about 130°C.

[0077] The weight-average molecular weight (Mw) of the pure monomer resin can be from about 300 g / mol to about 10,000 g / mol, particularly from about 1,000 g / mol to about 7,000 g / mol, and more preferably from about 1,350 g / mol to about 7,000 g / mol. The z-average molecular weight (Mz) of the pure monomer resin can be from about 1,000 g / mol to about 20,000 g / mol, particularly from about 1,500 g / mol to about 15,000 g / mol, and more preferably from about 2,000 g / mol to 15,000 g / mol. The molecular weight distribution (PDI) of the pure monomer resin is from about 1 to 3, for example from about 1 to about 2.7, particularly from about 1.1 to about 2.65.

[0078] Furthermore, the ratio of Z-average molecular weight to weight-average molecular weight (Mz / Mw) of pure monomer resins is less than about 2.5, particularly less than or equal to 2.0, for example less than or equal to about 1.84, and more particularly about 1.6 to about 1.835. Within this range, pure monomer resins can have consistent properties.

[0079] In one embodiment, the pure monomer resin has a small amount of volatile organic compounds, a low yellowing index, and good thermal stability.

[0080] Since the pure monomer resin of the present invention does not have the problems of resin decomposition or pollution and has good physical properties, the pure monomer resin can be used as a binder, electric vehicle tire additive, and the like.

[0081] Another aspect of the present invention relates to a method for controlling the properties of pure monomer resins. The method includes controlling the reaction temperature, monomer concentration, and reaction time during the single-stage thermal polymerization of a monomer solution in a continuous stirred tank reactor (CSTR) under catalyst-free conditions. In one embodiment, the concentration of aromatic vinyl monomers fed into the CSTR can be reduced to narrower the polydispersity index (PDI) of the pure monomer resin. In another embodiment, the reaction temperature in the CSTR can be lowered to reduce the amount of low molecular weight oligomers produced.

[0082] In one embodiment, the method may conform to Equation 1:

[0083] [Formula 1]

[0084] 100 × [(A1-A2) / A1] ≥ 10,

[0085] Where A2 represents the ratio (%) of the area of ​​low molecular weight oligomers (residence time: 21.6 min to 24.1 min) to the total area of ​​the polymer in the GPC analysis of polymers obtained by single-stage thermal polymerization in a continuous stirred tank reactor, and A1 represents the ratio (%) of the area of ​​low molecular weight oligomers (residence time: 21.6 min to 24.1 min) to the total area of ​​the polymer in the GPC analysis of polymers obtained by two-stage thermal polymerization.

[0086] The invention will now be described in more detail with reference to some embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the invention in any way. [Example]

[0087] Example 1 A monomer solution was prepared by mixing 1,350 g of styrene and 150 g of α-methylstyrene in 1,500 g of solvent (xylene). The monomer solution was continuously fed into a stirred tank reactor (400 mL internal volume) and polymerization was carried out at 270°C and 25 bar for 80 minutes. The solvent and some low-molecular-weight oligomers were separated from the polymerization product using a thin-film evaporator (TFE) at 230°C and 2 mbar to recover pure monomer resin.

[0088] Comparative Example 1 A monomer solution was prepared by mixing 1,350 g of styrene and 150 g of α-methylstyrene in 1,500 g of xylene. The monomer solution was continuously fed into a continuous stirred tank reactor (400 mL internal volume) for primary polymerization at 280 °C and 25 bar (reaction time 40 min). The product of the primary polymerization was then continuously fed into a plug flow reactor (600 mL internal volume, connected to the continuous stirred tank reactor) for secondary polymerization at 280 °C and 25 bar (reaction time 60 min). The solvent and some low-molecular-weight oligomers were separated from the polymerization product using a thin-film evaporator (TFE) at 230 °C and 2 mbar to recover pure monomer resin.

[0089] Figure 2 shows the results of GPC analysis of the pure monomer resins prepared in Example 1 and Comparative Example 1 before they were fed into the thin-film evaporator.

[0090] The reaction conditions are shown in Table 1, and the results of the property evaluation are shown in Table 2.

[0091] Table 1 Monomer solution (Styrene:α-methylstyrene:solvent) Aggregation conditions Example 1 45:5:50 Continuous stirred tank reactor (270°C, 80 minutes) Comparative Example 1 45:5:50 Continuous stirred tank reactor (280°C, 40 min) – plug flow reactor (280°C, 60 min)

[0092] Table 2 Mw Mn Mz PDI Low molecular weight oligomers%* Softening point (°C) Aromatic components (%) Olefin component (%) Aliphatic components (%) Example 1 1,493 852 2,621 1.75 twenty one 78 60.01 1.62 38.37 Comparative Example 1 1,480 777 2,925 1.91 26 72 59.50 1.86 38.64

[0093] As can be seen from Example 1 and Comparative Example 1, the proportion of low molecular weight oligomers in the pure monomer resin prepared by the method of the present invention can be reduced by 19.23% (as calculated according to Formula 1), and the softening point is increased. Furthermore, it is known that the pure monomer resin of the present invention has a narrow molecular weight distribution and a significantly reduced olefin content.

[0094] Example 2 The pure monomer resin was prepared in the same manner as in Example 1, except that the polymerization temperature was 260°C.

[0095] Comparative Example 2 The pure monomer resin was prepared in the same manner as in Example 2, except that polymerization was carried out under the conditions listed in Table 3.

[0096] Figure 3 shows the results of GPC analysis of the pure monomer resins prepared in Example 2 and Comparative Example 2 before they were fed into the thin-film evaporator.

[0097] The reaction conditions are shown in Table 3, and the results of the property evaluation are shown in Table 4.

[0098] Table 3 Monomer solution (Styrene:α-methylstyrene:solvent) Aggregation conditions Example 2 45:5:50 Continuous stirred tank reactor (260°C, 80 minutes) Comparative Example 2 45:5:50 Continuous stirred tank reactor (270°C, 40 min) - plug flow reactor (270°C, 60 min)

[0099] Table 4 Mw Mn Mz PDI Low molecular weight oligomers%* softening point (°C) Aromatic components (%) Olefin component (%) Aliphatic components (%) Example 2 2,515 1,297 4,444 1.94 16 90 61.02 1.52 37.46 Comparative Example 2 2,441 1,215 4,523 2.0 18 85 60.30 2.32 37.39

[0100] As can be seen from Example 2 and Comparative Example 2, the proportion of low molecular weight oligomers in the pure monomer resin prepared by the method of the present invention can be reduced by 11.1% (as calculated according to Formula 1), and the softening point is increased. Furthermore, it is known that the pure monomer resin of the present invention has a narrow molecular weight distribution and a significantly reduced olefin content.

[0101] Example 3 The pure monomer resin was prepared in the same manner as in Example 1, except that only styrene was used as the monomer and polymerization was carried out under the conditions listed in Table 5.

[0102] Comparative Example 3 The pure monomer resin was prepared in the same manner as in Example 3, except that polymerization was carried out under the conditions listed in Table 5.

[0103] The reaction conditions are shown in Figure 5, and the results of the property evaluation are shown in Figure 6.

[0104] Table 5 Monomer solution (Styrene: solvent) Aggregation conditions Example 3 50:50 Continuous stirred tank reactor (260°C, 80 minutes) Comparative Example 3 50:50 Continuous stirred tank reactor (270°C, 40 min) - plug flow reactor (270°C, 60 min)

[0105] Table 6 Mw Mn Mz PDI Low molecular weight oligomers%* Softening point (°C) Aromatic components (%) Olefin component (%) Aliphatic components (%) Example 3 3,239 1,539 5,654 2.10 12 98 61.69 1.20 37.11 Comparative Example 3 2,974 1,349 5,572 2.20 16 90 61.16 1.89 36.95

[0106] As can be seen from Example 3 and Comparative Example 3, the proportion of low molecular weight oligomers in the pure monomer resin prepared by the method of the present invention can be reduced by 25% (as calculated according to Formula 1), and the softening point is increased. Furthermore, it is known that the pure monomer resin of the present invention has a narrow molecular weight distribution and a significantly reduced olefin content.

[0107] Example 4 2,430 g of styrene and 270 g of isoprene were mixed in 300 g of solvent (xylene) to prepare a monomer solution. The monomer solution was continuously fed into a continuous stirred tank reactor (internal volume 400 mL) and polymerization was carried out at 270 °C and 25 bar (reaction time 80 min). The solvent and some low molecular weight oligomers of the polymerization products were separated from the polymer by a thin-film evaporator (TFE) at 230 °C and 2 mbar to recover pure monomer resin.

[0108] Example 5 2,160 g of styrene and 540 g of isoprene were mixed in 300 g of xylene to prepare a monomer solution. The monomer solution was continuously fed into a continuous stirred tank reactor (internal volume 400 mL), and polymerization was carried out at 270°C and 25 bar (reaction time 80 min). The solvent and some low-molecular-weight oligomers of the polymerization products were separated from the polymerization product using a thin-film evaporator (TFE) at 230°C and 2 mbar to recover pure monomer resin.

[0109] Table 7 Monomer solution (Styrene:imoprene:solvent) Aggregation conditions Example 4 81 : 9 : 10 Continuous stirred tank reactor (270°C, 40 minutes) Example 5 72:18:10 Continuous stirred tank reactor (270°C, 40 minutes)

[0110] Table 8 Mw Mn Mz PDI Low molecular weight oligomers%* softening point (°C) Aromatic components (%) Olefin component (%) Aliphatic components (%) Example 4 4434 1688 8143 2.63 10 102 55.74 2.08 42.18 Example 5 3975 1504 7470 2.64 12.5 94 50.53 3.61 45.86

[0111] As can be seen from the above examples, the pure monomer resin prepared according to the method of the present invention has a low molecular weight oligomer ratio of less than or equal to 12.5%, a softening point greater than or equal to 90°C, and a narrow molecular weight distribution.

[0112] Nature Assessment

[0113] (1) Molecular weight

[0114] The weight-average molecular weight (Mw), number-average molecular weight (Mn), and Z-average molecular weight (Mz) were measured using polystyrene standard samples via gel permeation chromatography (GPC, Viscotek TDA302 and Agilent 1200 series (pump)).

[0115] The analyte resin was dissolved in tetrahydrofuran to prepare a resin solution with a concentration of 4,000 ppm, and 100 μL of the resin solution was injected into a GPC column. The mobile phase of the GPC, tetrahydrofuran, was injected into the column at a rate of 1.0 mL / min, and analysis was performed at 35 °C. The column was a PL Mixed C2 group + PL 50 Å (Agilent). The detector was an RI detector (Viscotek RI), and measurements were performed at 35 °C. Mw, Mn, and Mz values ​​were obtained from the black curves generated after measuring polystyrene standards. Twelve polystyrene standards were used, with molecular weights of 104 / 118 / 236 / 580 / 1,480 / 2,340 / 2,970 / 5,030 / 8,450 / 10,850 / 20,650 / 24,600.

[0116] The measured weight-average molecular weight is divided by the number-average molecular weight to calculate the PDI (polymer dispersibility index).

[0117] (2) Low molecular weight oligomers

[0118] GPC analysis was performed on the polymer solution before it was fed into the thin-film evaporator to obtain the ratio of the area of ​​low molecular weight oligomers (residence time of 21.6 min to 24.1 min) to the total area of ​​the polymer.

[0119] (3) Softening point

[0120] According to ASTM E28, the softening point of each resin was measured twice using an Anton Paar RKA5 and the average value was taken.

[0121] (4) NMR analysis

[0122] Nuclear magnetic resonance (1H-NMR) analysis was performed on the pure monomer resins prepared in the examples and comparative examples.

[0123] Specifically, the pure monomeric resins prepared in the examples and comparative examples were dissolved in a solvent (CDCl3) to obtain a 2.5 wt% solution. The solution was then analyzed using a nuclear magnetic resonance spectrometer (600 NMR, 14.1 telsa, Bruker) at 600 MHz, acquisition time: 2.75 seconds, delay time: 1 second, number of scans: 128, pulse rate: 30 degrees Celsius, and the solvent being CDCl3.

[0124] Based on the results of 1H NMR analysis and Equation 1, the aromatic components (aromaticity, %) of each pure monomer resin can be obtained.

[0125] In Equation 1, ArA represents the ratio of the hydrogen peak area bonded to aromatic hydrocarbons (occurring in the aromatic region, specifically 6.5 ppm to 8.5 ppm) to the total peak area in the 1H-NMR spectrum. OA represents the ratio of the hydrogen peak area bonded to aromatic hydrocarbons (occurring in the olefin region, specifically 4.0 ppm to 6.5 ppm) to the total peak area in the spectrum. AlA represents the ratio of the hydrogen peak area bonded to aliphatic hydrocarbons (occurring in the aliphatic region, specifically 0.1 ppm to 40 ppm) to the total peak area in the spectrum. Peak areas are calculated by integration.

[0126] It should be understood that those skilled in the art can make various adjustments, changes, modifications, and equivalent embodiments without departing from the spirit and scope of the invention.

[0127] 1: Continuous stirred tank reactor

Claims

1. A method for preparing a pure monomer resin with a reduced proportion of low molecular weight oligomers, comprising: Multiple monomers, including an aromatic vinyl monomer, are thermally polymerized under catalyst-free conditions. The thermal polymerization is completed in a single stage in a continuous stirred tank reactor (CSTR) without secondary thermal polymerization in a plug flow reactor (PFR). The pure monomer resin has a weight average molecular weight (Mw) of 300 g / mol to 10,000 g / mol.

2. A method for preparing a pure monomeric resin as claimed in claim 1, wherein the monomers comprise 60 wt% to 100 wt% of the aromatic vinyl monomer and 0 to 40 wt% of a comonomer, and the comonomer is a hydrogenated aromatic vinyl monomer, a C4 to C10 olefin monomer, or a combination thereof.

3. The method for preparing a pure monomeric resin as claimed in claim 1, wherein the aromatic vinyl monomer is selected from styrene, alkylstyrene, divinylbenzene, indene, alkylindene, vinyltoluene, and a mixture of C9 oils.

4. The method for preparing a pure monomer resin as claimed in claim 1, wherein the monomers and a solvent are continuously fed into the continuous stirred tank reactor, the monomers being in a content of 20 wt% to 100 wt% and the solvent being in a content of 0 to 80 wt%.

5. The method for preparing the pure monomer resin as claimed in claim 1, wherein the temperature of the thermal polymerization step is from 150°C to 300°C and the pressure is from 5 bar to 30 bar.

6. A method for preparing the pure monomer resin as described in claim 1, conforming to Formula 1: [Formula 1] 100 × [(A1-A2) / A1] ≥ 10, where A2 represents the ratio (%) of the area of ​​the low molecular weight oligomer (residence time: 21.6 min to 24.1 min) to the total area of ​​the polymer in the GPC analysis of the polymer obtained by single-stage thermal polymerization in the continuous stirred tank reactor, wherein the single-stage thermal polymerization is carried out in a continuous stirred tank reactor (CSTR) with an internal volume of 400 ml at a temperature of 200 to 295°C and a constant temperature of 5 to 30°C. The reaction time is 5 to 180 minutes under a pressure of 5 to 30 bar, and A1 represents the ratio (%) of the area of ​​low molecular weight oligomers (residence time: 21.6 min to 24.1 min) to the total area of ​​the polymer in the GPC analysis of the polymer obtained by the two-stage thermal polymerization. The two-stage thermal polymerization is carried out by sequentially performing a primary polymerization and a secondary polymerization. The primary polymerization is carried out in the continuous stirred tank reactor (CSTR) under the same conditions as the single-stage thermal polymerization, while the secondary polymerization is carried out in a plug flow reactor (PFR) with an internal volume of 600 ml for a reaction time of 5 to 180 minutes at a temperature of 200 to 295°C and a pressure of 5 to 30 bar.

7. A pure monomeric resin prepared by the method of any one of claims 1 to 6, comprising: Weight-average molecular weight (Mw) is 300 g / mol to 10,000 g / mol; Z-average molecular weight (Mz) is 1,000 g / mol to 20,000 g / mol; molecular weight distribution (polymer dispersibility index) is 1 to 3; and softening point is 0°C to 150°C.

8. The pure monomer resin as claimed in claim 7, wherein the pure monomer resin contains less than 100 ppm of residual halides.

9. The pure monomer resin as claimed in claim 7, wherein the pure monomer resin conforms to Formula 2: [Formula 2] Io = OA × A2 < 35, where Io represents the low molecular weight oligomer index, OA represents the ratio (%) of the olefin region (4.0 ppm to 6.5 ppm region) to the total peak area calculated by integration in the 1H-NMR analysis, and A2 represents the ratio (%) of the area of ​​the low molecular weight oligomer (residence time: 21.6 min to 24.1 min) to the total area of ​​the polymer in the GPC analysis of the polymer.

10. The pure monomer resin as claimed in claim 7, wherein the ratio of the Z-average molecular weight to the weight-average molecular weight (Mz / Mw) of the pure monomer resin is less than 2.

5.

11. The pure monomer resin as claimed in claim 7, wherein the pure monomer resin has an aromatic component of 40% to 62.5%, an aliphatic component of 35% to 60%, and an olefin component of less than or equal to 5%.

12. A bonding agent comprising the pure monomeric resin described in claim 8.

13. A method for reducing the proportion of low molecular weight oligomers in a pure monomer resin, comprising thermally polymerizing an aromatic vinyl monomer in a single reactor under catalyst-free conditions, wherein the thermal polymerization is completed only through a single-stage polymerization in a continuous stirred tank reactor, and the polymer obtained by thermal polymerization is not subjected to secondary thermal polymerization in a plug flow reactor, wherein the weight-average molecular weight (Mw) of the pure monomer resin is from 300 g / mol to 10,000 g / mol.

14. The method of claim 13, wherein the method conforms to Equation 1: [Equation 1] 100 × [(A1-A2) / A1] ≥ 10, wherein A2 represents the ratio (%) of the area of ​​low molecular weight oligomers (residence time: 21.6 min to 24.1 min) to the total area of ​​the polymer in the GPC analysis of the polymer obtained by single-stage thermal polymerization in the continuous stirred tank reactor, wherein the single-stage thermal polymerization is carried out in the continuous stirred tank reactor (CSTR) with an internal volume of 400 ml for a reaction time of 5 to 180 minutes at a temperature of 200 to 295°C and a pressure of 5 to 30 bar, and A1 represents the ratio (%) of the area of ​​low molecular weight oligomers (residence time: 21.6 min to 24.1 min) to the total area of ​​the polymer in the GPC analysis of the polymer obtained by two-stage thermal polymerization. The two-stage thermal polymerization is carried out by sequentially performing a primary polymerization and a secondary polymerization. The primary polymerization is carried out in the continuous stirred tank reactor (CSTR) under the same conditions as the single-stage thermal polymerization, while the secondary polymerization is carried out in a plug flow reactor (PFR) with an internal volume of 600 ml for a reaction time of 5 to 180 minutes at a temperature of 200 to 295°C and a pressure of 5 to 30 bar.

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