Propylene / alpha-olefin copolymer as well as preparation method and application thereof

Abstract

The invention relates to the technical field of polymer synthesis and processing, in particular to a propylene / alpha-olefin copolymer as well as a preparation method and application thereof, and aims to solve the problems that the melting temperature of the propylene / alpha-olefin copolymer is relatively high, the melting range is relatively narrow, the toughness and the strength of a heat-sealing material cannot be effectively balanced and the like in the prior art. The invention relates to a propylene / alpha-olefin copolymer, the melting peak temperature of the propylene / alpha-olefin copolymer is 40-90 DEG C, the melting range width is 40-80 DEG C, and the melting peak number n (peak) and dH (100) of the propylene / alpha-olefin copolymer meet the following conditions: 6 < = n (peak) < = 20, and dH (100) = 0.

Description

Technical Field

[0001] The present application relates to the technical field of polymer synthesis and processing, and in particular to a propylene / α-olefin copolymer and a preparation method and application thereof. Background Art

[0002] The polymer obtained by copolymerization of propylene and α-olefins has excellent properties such as high elasticity, high transparency, and good low-temperature toughness, and is currently an important direction for the development of high-end polyolefin materials. In particular, propylene / α-olefin copolymers have good compatibility with polypropylene and are used to modify polypropylene products. For example, propylene / α-olefin copolymers are often used in polypropylene heat-sealing materials to enhance their low-temperature toughness.

[0003] However, the melting temperature of the current propylene / α-olefin copolymer is relatively high. When it is applied to polypropylene heat-sealing materials, the cooling and sealing time during the heat-sealing process is long. In addition, due to the narrow melting range of the propylene / α-olefin copolymer, it is easy to cause seal wrinkling and wire drawing, resulting in poor heat sealing. In addition, the insertion rate of α-olefin in the propylene / α-olefin copolymer will affect the toughness and strength of the heat-sealing material. How to balance the toughness and strength of the heat-sealing material has become a problem that needs to be solved urgently. Summary of the invention

[0004] Based on this, some embodiments of the present application provide a propylene / α-olefin copolymer and a preparation method and application thereof to solve the problems in the related art that the propylene / α-olefin copolymer has a high melting temperature and a narrow melting range, and cannot effectively balance the toughness and strength of the heat sealing material.

[0005] In a first aspect, a propylene / α-olefin copolymer is provided, wherein the melting peak temperature of the propylene / α-olefin copolymer is 40°C~90°C, the melting range width is 40°C~80°C, and the melting peak number n(peak) and dH(100) of the propylene / α-olefin copolymer satisfy: 6≤n(peak)≤20, dH(100)=0.

[0006] The melting peak temperature, melting range, melting peak number n(peak) and dH(100) of the propylene / α-olefin copolymer can be measured by differential scanning calorimeter (DSC).

[0007] n(peak) is the number of melting peaks. In the results of continuous self-nucleation / annealing SSA measurements performed using a differential scanning calorimeter, when the heat capacity of each segment of the polymer is fractionated relative to the total heat capacity by integrating the temperature-heat capacity curves of different segments of the polymer, n(peak) represents the number of melting peaks in the SSA measurements. dH(100) represents the sum of the melting enthalpies above 100°C.

[0008] Therefore, n(peak) reflects the regions in the polymer with various different crystal forms or different degrees of crystallization perfection. In the same polymer, differences in the polymer segment structure will lead to multiple melting peaks. For example, in propylene / α-olefin copolymers, the polypropylene segment and the polyα-olefin segment have different crystallization characteristics, and there will be melting peaks corresponding to the crystallization of these two segments; similarly, in multiple copolymer segments of propylene and α-olefin, copolymer segments with different α-olefin insertion rates also have different crystallization characteristics, and there will be multiple melting peaks corresponding to different copolymer segments.

[0009] Among them, according to the different insertion rates of α-olefin in different copolymer segments, the corresponding melting points of each copolymer segment are also different. For example, the lower the insertion rate of α-olefin is, the higher the melting point is, and vice versa.

[0010] In the embodiments of the present application, the larger the n(peak), the more segments with different crystallization characteristics there are in the polymer, that is, the more segments with different α-olefin insertion rates there are in the polymer, that is, the propylene / α-olefin copolymer has multiple segments with different α-olefin insertion rates, and accordingly, the wider the melting range of the polymer is, and dH(100) reflects the sum of the melting enthalpies of the polymer above 100°C, dH(100)=0, indicating that the heat absorbed and released by the changes in the intermolecular forces within the polymer and the transition between the crystalline state and the amorphous state at 100°C cancel each other out, there is no transition between the crystalline state and the amorphous state, and the polymer has a lower melting peak temperature.

[0011] In the propylene / α-olefin copolymer provided in the embodiment of the present application, the propylene / α-olefin copolymer has a lower melting peak temperature, dH(100)=0, and therefore, there is no high crystallization peak in the propylene / α-olefin copolymer, so it is easier to melt. When it is applied to heat-sealing materials, the heat-sealing temperature can be effectively reduced and the heat-sealing efficiency can be improved. At the same time, since the melting range width of the propylene / α-olefin copolymer is relatively large, and 6≤n(peak)≤20, it means that the propylene / α-olefin copolymer has multiple segments with different α-olefin insertion rates. When it is applied to heat-sealing materials, the cooling and sealing time in the heat-sealing process can be effectively shortened, and the phenomena such as seal wrinkling and wire drawing can be reduced, thereby reducing poor heat sealing.

[0012] In addition, when the propylene / α-olefin copolymer is applied to a heat-sealing material, the segment with a lower melting point among the multiple segments with different α-olefin insertion rates of the propylene / α-olefin copolymer can have a better toughening effect, and the segment with a higher melting point among the multiple segments with different α-olefin insertion rates can increase the compatibility between the propylene / α-olefin copolymer and the base material such as polypropylene, and reduce the influence on the strength of the heat-sealing material, so that the toughness and strength of the heat-sealing material can be effectively balanced. In summary, when the propylene / α-olefin copolymer is applied to a heat-sealing material, the comprehensive performance of the heat-sealing material can be effectively improved.

[0013] Optionally, the propylene / α-olefin copolymer satisfies at least one of the following conditions:

[0014] (1) The density of propylene / α-olefin copolymer is 0.840 g / cm 3 ~0.880g / cm 3 ;

[0015] (2) The weight average molecular weight of the propylene / α-olefin copolymer is 100,000 g / mol to 300,000 g / mol;

[0016] (3) The molecular weight distribution width PDI of propylene / α-olefin copolymer is 2.0~3.5;

[0017] (4) The melting enthalpy of propylene / α-olefin copolymer is 10 J / g ~100 J / g;

[0018] (5) The melt index of propylene / α-olefin copolymer at 230°C and 2.16 kg load is 1.0 g / 10min~50.0 g / 10min;

[0019] (6) The glass transition temperature Tg of propylene / α-olefin copolymer is -35℃~-15℃;

[0020] (7) The α-olefin in the propylene / α-olefin copolymer is selected from C2~C 20 At least one of the olefins;

[0021] (8) The mass fraction of α-olefin in the propylene / α-olefin copolymer is 5%~25%.

[0022] In a second aspect, a method for preparing a propylene / α-olefin copolymer is provided, comprising:

[0023] A reactor group is provided, the reactor group comprising: a multi-stage reactor connected in series, each stage of the reactor having a reaction material inlet and a reaction material outlet arranged opposite to each other along the axial direction of the reactor, the reaction material outlet of the previous stage of the reactor being connected to the reaction material inlet of the next stage of the reactor, the aspect ratio of each stage of the reactor being less than or equal to 3, and at least two stages of the multi-stage reactors having different aspect ratios and / or volumes; wherein the aspect ratio of each stage of the reactor is equal to the ratio of a first dimension to a second dimension, the first dimension being the dimension from the reaction material inlet to the reaction material outlet of the reactor, and the second dimension being the radial dimension of the reactor;

[0024] Controlling multiple batches of reaction materials to be respectively introduced into each stage of the reactor, and controlling different batches of the reaction materials to polymerize with the reaction product of the previous stage reactor in each stage of the reactor in sequence to prepare the propylene / α-olefin copolymer; and

[0025] The propylene / α-olefin copolymer prepared in the last-stage reactor is quenched and devolatilized to obtain the propylene / α-olefin copolymer;

[0026] Wherein, each batch of the reaction materials at least includes: propylene monomer, α-olefin monomer, solvent and catalyst.

[0027] Among them, for the reactor with a larger aspect ratio, the mixed mass transfer effect is good, at this time, the temperature, catalyst and monomer concentration distribution inside the reactor are relatively uniform, the polymerization environment of the polymerization active site is basically the same, and the properties of the resulting polymer products are relatively uniform. For the reactor with a smaller aspect ratio, the mixed mass transfer and heat transfer efficiency are relatively poor, and there is an uneven distribution of monomer ratios inside the reactor, so that polymer segments with multiple different α-olefin insertion rates can be prepared, and polymer segments with different crystallization abilities can be constructed in the polymer molecular chain, so that a polymer with a larger melting peak number n (peak) can be obtained, and the melting range width of the propylene / α-olefin copolymer can be increased.

[0028] The residence time of the reaction material in the reactor is equal to the volume of the reactor divided by the flow rate of the reaction material. Therefore, for reactors of different volumes, when the volume of the reactor is larger, the residence time of the reaction material in the reactor is longer, and more segments and / or molecular chains are obtained; conversely, the residence time of the reaction material in the reactor is shorter, and fewer segments and / or molecular chains are obtained. Since the aspect ratio of each stage of the reactor is less than or equal to 3, the uneven distribution of the monomer ratio can be achieved, thereby preparing polymer segments with multiple different α-olefin insertion rates, and achieving the construction of polymer segments with different crystallization abilities in the polymer molecular chain, so that a polymer with a larger melting peak number n (peak) can be obtained, and the melting range width of the propylene / α-olefin copolymer can be increased.

[0029] Among them, the propylene monomer, solvent and co-catalyst contained in the catalyst in each batch of reaction materials can be pre-mixed and then introduced into each level of reactors, and the remaining raw materials are introduced into each level of reactors through separate feeding pipelines, so that each batch of reaction materials can react under a certain temperature and pressure after entering each level of reactors.

[0030] When corresponding batches of reactants are introduced into each stage of the reactor, the reaction product obtained by polymerizing the previous batch of reactants in the previous stage reactor, such as the first segment, continues to react with the current batch of reactants in the current stage reactor to generate another segment, such as the second segment. When the aspect ratio and / or volume of the previous stage reactor and the subsequent stage reactor are different, the arrangement of the first segment and the second segment and the insertion rate of α-olefin are different. By controlling the aspect ratio of each stage reactor to be smaller, the random insertion degree of the α-olefin distribution in each stage reactor can be increased, thereby preparing a propylene / α-olefin copolymer with a low melting peak temperature, a large n (peak) and a large melting range width.

[0031] In the preparation method of the propylene / α-olefin copolymer provided in the embodiment of the present application, since the aspect ratio of each reactor in the reactor group is less than or equal to 3, the monomer ratios in the reaction materials introduced into different reactors can be unevenly distributed, thereby improving the random insertion degree of α-olefin in the propylene / α-olefin copolymer; at the same time, by controlling the aspect ratios and / or volumes of at least two reactors to be different from each other, the insertion rate and / or segment length of α-olefin in the reaction material in each reactor can be effectively controlled, thereby further improving the random insertion degree of α-olefin in the propylene / α-olefin copolymer, increasing the number of melting peaks and the melting range width of the propylene / α-olefin copolymer, and further preparing a propylene / α-olefin copolymer with a low melting peak temperature, no high crystallization peak and a large melting range width. After the preparation of the propylene / α-olefin copolymer, the reaction can be terminated in time by quenching and devolatilizing the propylene / α-olefin copolymer, thereby avoiding the introduction of polymer segments with high crystallinity into the propylene / α-olefin copolymer, thereby controlling the dH(100) of the propylene / α-olefin copolymer to be 0.

[0032] In some embodiments, the aspect ratio of each reactor stage is 0.5-3.

[0033] In some embodiments, the preparation method includes: controlling the stirring conditions, temperature and pressure in each stage of the reactor to be the same.

[0034] The same stirring conditions mean that the specifications and rotation speed of the stirring blades used for stirring are the same and do not change with the aspect ratio and volume of the reactor.

[0035] In these embodiments, by controlling the stirring conditions, temperature and pressure in each stage of the reactor to be the same, the difficulty of operation can be reduced, and the reactants entering each stage of the reactor can be controlled by aspect ratio and / or volume to obtain a propylene / α-olefin copolymer with a low melting peak temperature, no high crystallization peak and a wide melting range.

[0036] Optionally, the temperature in each stage of the reactor is 80° C. to 220° C., and the pressure is 2 MPa to 10 MPa.

[0037] Optionally, the preparation method satisfies at least one of the following conditions:

[0038] (1) The mass ratio of propylene monomer to α-olefin monomer in different batches of reaction materials is the same or different;

[0039] (2) In each batch of reaction materials, the mass proportion of α-olefin monomer in propylene monomer and α-olefin monomer is 5%~25%;

[0040] (3) α-olefin monomer is selected from C2~C 20 At least one of the olefins.

[0041] When the mass ratio of propylene monomer to α-olefin monomer in different batches of reaction materials is the same, the degree of heterogeneity and / or degree of polymerization of propylene monomer and α-olefin monomer in two-stage reactors with different aspect ratios and / or different volumes will also be different, so that more segments with different melting capabilities can be formed in the propylene / α-olefin copolymer; when the mass ratio of propylene monomer to α-olefin monomer in different batches of reaction materials is different, in the two-stage reactors with the same aspect ratio and / or the same volume, the degree of heterogeneity and / or degree of polymerization of propylene monomer and α-olefin monomer will also be different, so that more segments with different melting capabilities can be formed in the propylene / α-olefin copolymer.

[0042] Optionally, the preparation method further comprises:

[0043] A quenching kettle is connected to the reaction material outlet of the last stage reactor of the reactor group, and a devolatilization device is connected to the outlet of the quenching kettle, so that the propylene / α-olefin copolymer prepared in the last stage reactor is quenched and devolatilized in sequence by the quenching kettle and the devolatilization device to obtain the propylene / α-olefin copolymer.

[0044] In this process, quenching is performed first and then devolatilization is performed, so that the residual catalyst activity in the polymerization reaction liquid can be quenched in time after the polymerization is completed, so as to avoid the generation of polymer chain segments with high crystallinity in the subsequent devolatilization process, and ensure that there is no high crystallinity peak in the propylene / α-olefin copolymer, so that dH(100) of the propylene / α-olefin copolymer is 0.

[0045] In a third aspect, there is provided a use of the propylene / α-olefin copolymer as described in the first aspect in the preparation of a heat-sealing material.

[0046] Optionally, the propylene / α-olefin copolymer is mixed with a polypropylene material in a mass ratio of 1:(4-19), and a casting film is prepared by a casting process to prepare the heat sealing material.

[0047] Compared with the related art, this application has at least the following beneficial technical effects:

[0048] The propylene / α-olefin copolymer has a relatively low melting peak temperature, dH(100)=0. Therefore, the propylene / α-olefin copolymer has no high crystallization peak and is therefore easier to melt. When the propylene / α-olefin copolymer is applied to heat-sealing materials, the heat-sealing temperature can be effectively reduced and the heat-sealing efficiency can be improved. At the same time, since the melting range width of the propylene / α-olefin copolymer is relatively large and 6≤n(peak)≤20, it means that the propylene / α-olefin copolymer has multiple segments with different α-olefin insertion rates. When the propylene / α-olefin copolymer is applied to heat-sealing materials, the cooling and sealing time in the heat-sealing process can be effectively shortened, and the phenomena of seal wrinkling and wire drawing can be reduced, thereby reducing poor heat sealing.

[0049] In addition, when the propylene / α-olefin copolymer is applied to a heat-sealing material, the segment with a lower melting point among the multiple segments with different α-olefin insertion rates of the propylene / α-olefin copolymer can have a better toughening effect, and the segment with a higher melting point among the multiple segments with different α-olefin insertion rates can increase the compatibility between the propylene / α-olefin copolymer and the base material such as polypropylene, and reduce the influence on the strength of the heat-sealing material, so that the toughness and strength of the heat-sealing material can be effectively balanced. In summary, when the propylene / α-olefin copolymer is applied to a heat-sealing material, the comprehensive performance of the heat-sealing material can be effectively improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] Figure 1 A schematic diagram of the structure of a reactor group provided in an embodiment of the present application;

[0051] Figure 2 A schematic flow chart of a method for preparing a propylene / α-olefin copolymer provided in an embodiment of the present application. DETAILED DESCRIPTION

[0052] In order to facilitate the understanding of the present application, the present application will be described more fully below with reference to the relevant drawings. The preferred embodiments of the present application are given in the drawings. However, the present application can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the understanding of the disclosure of the present application more thorough and comprehensive.

[0053] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application belongs. The terms used herein in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application. The term "and / or" used herein includes any and all combinations of one or more of the related listed items.

[0054] The present application will be further described in detail below in conjunction with specific embodiments. The present application can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present application more thoroughly understood.

[0055] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application belongs. The terms used herein in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application.

[0056] In the present application, "at least one" refers to any one, any two, or any two or more of the listed items.

[0057] In the present application, the terms "combination thereof", "any combination thereof", "any combination thereof" and the like include all suitable combinations of any two or more of the listed items.

[0058] In the present application, the technical features described in an open manner include closed technical solutions composed of the listed features, and also include open technical solutions containing the listed features.

[0059] In the present application, reference to a numerical range includes both endpoints of the numerical range unless otherwise specified.

[0060] In this application, when it comes to percentage concentration, unless otherwise specified, it refers to the final concentration. The final concentration refers to the proportion of the added component in the system after the addition of the component.

[0061] In this application, when it comes to temperature parameters, unless otherwise specified, both constant temperature treatment and treatment within a certain temperature range are permitted. The constant temperature treatment allows the temperature to fluctuate within the precision range controlled by the instrument.

[0062] In view of the problems existing in the related art that the melting temperature of propylene / α-olefin copolymer is high, the melting range is narrow, and the toughness and strength of the heat-sealing material cannot be effectively balanced, the specific implementation methods of the present application are described as follows:

[0063] In a first aspect, some embodiments of the present application provide a propylene / α-olefin copolymer, wherein the melting peak temperature of the propylene / α-olefin copolymer is 40°C~90°C, the melting range width is 40°C~80°C, and the melting peak number n(peak) and dH(100) of the propylene / α-olefin copolymer satisfy: 6≤n(peak)≤20, dH(100)=0.

[0064] The melting peak temperature, melting range, melting peak number n(peak) and dH(100) of the propylene / α-olefin copolymer can be measured by differential scanning calorimetry (DSC).

[0065] When using a differential scanning calorimeter (DSC) to measure the thermal properties of a polymer, the melting peak temperature refers to the peak temperature of the endothermic peak on the DS curve when the polymer completely changes from a crystalline state to a liquid state. This temperature represents the temperature point at which the main crystalline part of the polymer melts.

[0066] Here, for different propylene / α-olefin copolymers, their melting peak temperatures and melting ranges may be different from each other. All propylene / α-olefin copolymers with melting peak temperatures in the range of 40°C to 90°C and melting range widths in the range of 40°C to 80°C are within the protection scope of the present application.

[0067] The melting range width here refers to the difference between the temperature at which the propylene / α-olefin copolymer is completely melted and the temperature at which it begins to melt, indicating the range covered by the melting range, and does not specifically refer to the temperature at which the melting range begins to melt and when it is completely melted.

[0068] For example, the melting peak temperature of the propylene / α-olefin copolymer may be 40°C. In this case, the melting range width is 40°C, which means that the melting range of the propylene / α-olefin copolymer may be 30°C to 70°C, and the melting range width is equal to the difference between the temperature of 70°C at which the propylene / α-olefin copolymer is completely melted and the temperature of 30°C at which the propylene / α-olefin copolymer begins to melt, that is, 40°C; or, the melting peak temperature of the propylene / α-olefin copolymer may be 50°C. In this case, the melting range width may be 40°C. In this case, the melting range of the propylene / α-olefin copolymer may be 35°C to 75°C. The melting range width is equal to the difference between the temperature of 75°C at which the propylene / α-olefin copolymer is completely melted and the temperature of 35°C at which the propylene / α-olefin copolymer begins to melt, that is, 40°C; or Alternatively, the melting peak temperature of the propylene / α-olefin copolymer may be 70°C, in which case the melting range width may be 50°C, in which case the melting range of the propylene / α-olefin copolymer may be 40°C-90°C, and the melting range width is equal to the difference between the temperature of 90°C at which the propylene / α-olefin copolymer is completely melted and the temperature of 40°C at which the propylene / α-olefin copolymer begins to melt, i.e., 50°C; or, the melting peak temperature of the propylene / α-olefin copolymer may be 90°C, in which case the melting range width may be 80°C, in which case the melting range of the propylene / α-olefin copolymer may be 40°C-120°C, and the melting range width is equal to the difference between the temperature of 120°C at which the propylene / α-olefin copolymer is completely melted and the temperature of 40°C at which the propylene / α-olefin copolymer begins to melt, i.e., 80°C.

[0069] When a polymer is measured using a differential scanning calorimeter (DSC), the melting peak represents the thermal transition signal when the polymer changes from a solid to a liquid during heating. n (peak) is the number of melting peaks. In the continuous self-nucleation / annealing SSA measurement results using a differential scanning calorimeter, when the heat capacity of each segment is graded relative to the total heat capacity by integrating the temperature-heat capacity curve of different segments of the polymer, n(peak) represents the number of melting peaks in the SSA measurement results, and dH(100) represents the sum of the melting enthalpies above 100°C.

[0070] Therefore, n(peak) reflects the regions in the polymer with various different crystal forms or different degrees of crystallization perfection. In the same polymer, differences in the polymer segment structure will lead to multiple melting peaks. For example, in propylene / α-olefin copolymers, the polypropylene segment and the polyα-olefin segment have different crystallization characteristics, and there will be melting peaks corresponding to the crystallization of these two segments; similarly, in multiple copolymer segments of propylene and α-olefin, copolymer segments with different α-olefin insertion rates also have different crystallization characteristics, and there will be multiple melting peaks corresponding to different copolymer segments.

[0071] Among them, according to the different insertion rates of α-olefin in different copolymer segments, the corresponding melting points of each copolymer segment are also different. For example, the lower the insertion rate of α-olefin is, the higher the melting point is, and vice versa.

[0072] In the embodiments of the present application, the larger the n(peak), the more segments with different crystallization characteristics there are in the polymer, that is, the more segments with different α-olefin insertion rates there are in the polymer, that is, the propylene / α-olefin copolymer has multiple segments with different α-olefin insertion rates, and accordingly, the wider the melting range of the polymer is, and dH(100) reflects the sum of the melting enthalpies of the polymer above 100°C, dH(100)=0, indicating that the heat absorbed and released by the changes in the intermolecular forces within the polymer and the transition between the crystalline state and the amorphous state at 100°C cancel each other out, there is no transition between the crystalline state and the amorphous state, and the polymer has a lower melting peak temperature.

[0073] In the propylene / α-olefin copolymer provided in the embodiment of the present application, the propylene / α-olefin copolymer has a lower melting peak temperature, dH(100)=0, and therefore, there is no high crystallization peak in the propylene / α-olefin copolymer, so it is easier to melt. When it is applied to heat-sealing materials, the heat-sealing temperature can be effectively reduced and the heat-sealing efficiency can be improved. At the same time, since the melting range width of the propylene / α-olefin copolymer is relatively large, and 6≤n(peak)≤20, it means that the propylene / α-olefin copolymer has multiple segments with different α-olefin insertion rates. When it is applied to heat-sealing materials, the cooling and sealing time in the heat-sealing process can be effectively shortened, and the phenomena such as seal wrinkling and wire drawing can be reduced, thereby reducing poor heat sealing.

[0074] In addition, when the propylene / α-olefin copolymer is applied to a heat-sealing material, the segment with a lower melting point among the multiple segments with different α-olefin insertion rates of the propylene / α-olefin copolymer can have a better toughening effect, and the segment with a higher melting point among the multiple segments with different α-olefin insertion rates can increase the compatibility between the propylene / α-olefin copolymer and the base material such as polypropylene, and reduce the influence on the strength of the heat-sealing material, so that the toughness and strength of the heat-sealing material can be effectively balanced. In summary, when the propylene / α-olefin copolymer is applied to a heat-sealing material, the comprehensive performance of the heat-sealing material can be effectively improved.

[0075] In some embodiments, the propylene / α-olefin copolymer has a density of 0.840 g / cm 3 ~0.880g / cm 3 For example, the density of the propylene / α-olefin copolymer may be 0.840 g / cm 3 , 0.845g / cm 3 、0.850g / cm3 , 0.855g / cm 3 , 0.861g / cm 3 , 0.868g / cm 3 、0.870g / cm 3 , 0.872g / cm 3 , 0.874g / cm 3 , 0.876g / cm 3 、0.878g / cm 3 or 0.880g / cm 3 wait.

[0076] In some embodiments, the weight average molecular weight of the propylene / α-olefin copolymer is 100000 g / mol to 300000 g / mol. For example, the weight average molecular weight of the propylene / α-olefin copolymer can be 100000 g / mol, 110000 g / mol, 120000 g / mol, 130000 g / mol, 140000 g / mol, 150000 g / mol, 160000 g / mol, 170000 g / mol, 180000 g / mol, 190000 g / mol, 200000 g / mol, 220000 g / mol, 235000 g / mol, 250000 g / mol, 270000 g / mol or 295000 g / mol, etc.

[0077] In some embodiments, the molecular weight distribution width PDI of the propylene / α-olefin copolymer is 2.0 to 3.5. The molecular weight distribution width PDI is a parameter used to describe the width of the molecular weight distribution of a polymer. The larger the PDI, the wider the molecular weight distribution of the polymer. For example, the molecular weight distribution width PDI of the propylene / α-olefin copolymer can be 2.2, 2.4, 2.6, 2.8, 3.0, 3.2 or 3.5.

[0078] In some embodiments, the melting enthalpy of the propylene / α-olefin copolymer is 10 J / g to 100 J / g. Melting enthalpy (also known as melting enthalpy) refers to the amount of heat absorbed by a unit mass of a solid substance when it is completely converted into a liquid at the same temperature at a certain pressure at the melting point. For example, the melting enthalpy of the propylene / α-olefin copolymer can be 10 J / g, 15 J / g, 22 J / g, 30 J / g, 37 J / g, 40 J / g, 50 J / g, 60 J / g, 80 J / g, 90 J / g or 95 J / g, etc.

[0079] In some embodiments, the melt index (MI) of the propylene / α-olefin copolymer at 230° C. and 2.16 kg load is 1.0 g / 10 min to 50.0 g / 10 min. For example, the melt index (MI) of the propylene / α-olefin copolymer at 230° C. and 2.16 kg load can be 1.0 g / 10 min, 1.5 g / 10 min, 2.5 g / 10 min, 3.5 g / 10 min, 5.0 g / 10 min, 9.0 g / 10 min, 13.0 g / 10 min, 17.0 g / 10 min, 22.0 g / 10 min, 28.0 g / 10 min, 33.0 g / 10 min, 38.0 g / 10 min, 42.0 g / 10 min, 47.0 g / 10 min, or 50.0 g / 10 min, etc.

[0080] In some embodiments, the glass transition temperature Tg of the propylene / α-olefin copolymer is -35°C to -15°C. The glass transition temperature Tg refers to the temperature at which an amorphous polymer (or an amorphous part in a partially crystalline polymer) transitions from a glassy state to a highly elastic state. For example, the glass transition temperature Tg of the propylene / α-olefin copolymer may be -35°C, -34°C, -31°C, -29°C, -26°C, -23°C, -20°C, -18°C, or -15°C, etc.

[0081] In some embodiments, the α-olefin in the propylene / α-olefin copolymer is selected from C2 to C 20 For example, the α-olefin may be selected from one or more of ethylene, 1-butene, 1-pentene, 4-methyl-1-pentene, 1-hexene, 1-heptene, 1-octene, 1-decene, 1-undecene, 1-dodecene, 1-tetradecene, 1-hexadecene and 1-eicosene.

[0082] In some embodiments, the mass fraction of α-olefin in the propylene / α-olefin copolymer is 5% to 25%. For example, the mass fraction of α-olefin can be 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 18%, 20%, 22% or 25%, etc.

[0083] Optionally, the mass fraction of α-olefin in the propylene / α-olefin copolymer is 8% to 15%.

[0084] In a second aspect, some embodiments of the present application provide a method for preparing a propylene / α-olefin copolymer, such as Figure 1 and Figure 2 As shown, the preparation method comprises:

[0085] S21. Provide a reactor group, the reactor group comprising: a multi-stage reactor 11 connected in series, each stage of the reactor 11 having a reaction material inlet 111 and a reaction material outlet 112 arranged opposite to each other along the axial direction of the reactor 11, the reaction material outlet 112 of the previous stage of the reactor 11 being connected to the reaction material inlet 111 of the next stage of the reactor 11, the aspect ratio of each stage of the reactor 11 being less than or equal to 3, and at least two stages of the reactors 11 in the multi-stage reactor 11 having different aspect ratios and / or volumes; wherein the aspect ratio of each stage of the reactor 11 is equal to the ratio of a first dimension to a second dimension, the first dimension being the dimension between the reaction material inlet 111 and the reaction material outlet 112 of the reactor 11, and the second dimension being the radial dimension of the reactor 11;

[0086] Among them, for the reactor with a larger aspect ratio, the mixed mass transfer effect is good, at this time, the temperature, catalyst and monomer concentration distribution inside the reactor are relatively uniform, the polymerization environment of the polymerization active site is basically the same, and the properties of the resulting polymer products are relatively uniform. For the reactor with a smaller aspect ratio, the mixed mass transfer and heat transfer efficiency are relatively poor, and there is an uneven distribution of monomer ratios inside the reactor, so that polymer segments with multiple different α-olefin insertion rates can be prepared, and polymer segments with different crystallization abilities can be constructed in the polymer molecular chain, so that a polymer with a larger melting peak number n (peak) can be obtained, and the melting range width of the propylene / α-olefin copolymer can be increased.

[0087] The residence time of the reactants in the reactor is equal to the volume of the reactor divided by the flow rate of the reactants. Therefore, for reactors of different volumes, when the volume of the reactor is larger, the residence time of the reactants in the reactor is longer, thereby obtaining more segments and / or molecular chains. Conversely, the residence time of the reactants in the reactor is shorter, thereby obtaining fewer segments and / or molecular chains. Since the aspect ratio of each stage of the reactor is less than or equal to 3, an uneven distribution of the monomer ratio can be achieved, thereby preparing polymer segments with multiple different α-olefin insertion rates, and constructing polymer segments with different crystallization abilities in the polymer molecular chain, thereby obtaining a polymer with a larger number of melting peaks n (peak), thereby increasing the melting range width of the propylene / α-olefin copolymer.

[0088] S22, controlling multiple batches of reaction materials to be respectively introduced into each stage of the reactor 11, and controlling different batches of reaction materials to be polymerized with the reaction product of the previous stage reactor 11 in sequence in each stage of the reactor 11, to prepare the propylene / α-olefin copolymer; and

[0089] S23, quenching and devolatilizing the propylene / α-olefin copolymer prepared in the last-stage reactor to obtain a propylene / α-olefin copolymer;

[0090] Each batch of reaction materials at least includes: propylene monomer, α-olefin monomer, solvent and catalyst.

[0091] Among them, the propylene monomer, solvent and co-catalyst contained in the catalyst in each batch of reaction materials can be pre-mixed and then introduced into each level of reactors, and the remaining raw materials are introduced into each level of reactors through separate feeding pipelines, so that each batch of reaction materials can react under a certain temperature and pressure after entering each level of reactors.

[0092] When corresponding batches of reactants are introduced into each stage of the reactor, the reaction product obtained by polymerizing the previous batch of reactants in the previous stage reactor, such as the first segment, continues to react with the current batch of reactants in the current stage reactor to generate another segment, such as the second segment. When the aspect ratio and / or volume of the previous stage reactor and the subsequent stage reactor are different, the arrangement of the first segment and the second segment and the insertion rate of α-olefin are different. By controlling the aspect ratio of each stage reactor to be smaller, the random insertion degree of the α-olefin distribution in each stage reactor can be increased, thereby preparing a propylene / α-olefin copolymer with a low melting peak temperature, a large n (peak) and a large melting range width.

[0093] In the preparation method of the propylene / α-olefin copolymer provided in the embodiment of the present application, since the aspect ratio of each reactor in the reactor group is less than or equal to 3, the monomer ratios in the reaction materials introduced into different reactors can be unevenly distributed, thereby improving the random insertion degree of α-olefin in the propylene / α-olefin copolymer; at the same time, by controlling the aspect ratios and / or volumes of at least two reactors to be different from each other, the insertion rate and / or segment length of α-olefin in the reaction material in each reactor can be effectively controlled, thereby further improving the random insertion degree of α-olefin in the propylene / α-olefin copolymer, increasing the number of melting peaks and the melting range width of the propylene / α-olefin copolymer, and further preparing a propylene / α-olefin copolymer with a low melting peak temperature, no high crystallization peak and a large melting range width. After the preparation of the propylene / α-olefin copolymer, the reaction can be terminated in time by quenching and devolatilizing the propylene / α-olefin copolymer, thereby avoiding the introduction of polymer segments with high crystallinity into the propylene / α-olefin copolymer, thereby controlling the dH(100) of the propylene / α-olefin copolymer to be 0.

[0094] In some embodiments, the aspect ratio of each reactor stage 11 is 0.5-3.

[0095] In some optional embodiments, the reactor group may include: 2~3 reactors connected in series. In the case where the reactor group includes 2 reactors connected in series, the aspect ratios and / or volume ratios of the two reactors are different; in the case where the reactor group includes 3 reactors connected in series, the aspect ratios and / or volume ratios of at least two reactors are different, which means that the aspect ratios and / or volume ratios of the first reactor and the second reactor are different, and the aspect ratios and volume ratios of the first reactor and the third reactor are the same, or the aspect ratios and / or volume ratios of the first reactor and the third reactor are different, and the aspect ratios and volume ratios of the first reactor and the second reactor are the same.

[0096] In some embodiments, the preparation method includes: controlling the stirring conditions, temperature and pressure in each stage of the reactor 11 to be the same.

[0097] The same stirring conditions mean that the specifications and rotation speed of the stirring blades used for stirring are the same and do not change with the aspect ratio and volume of the reactor.

[0098] In these embodiments, by controlling the stirring conditions, temperature and pressure in each stage of the reactor to be the same, the difficulty of operation can be reduced, and the reactants entering each stage of the reactor can be controlled by aspect ratio and / or volume to obtain a propylene / α-olefin copolymer with a low melting peak temperature, no high crystallization peak and a wide melting range.

[0099] In some embodiments, the mass ratios of propylene monomer and α-olefin monomer in different batches of reaction materials are the same or different.

[0100] In these embodiments, when the mass ratio of propylene monomer to α-olefin monomer in different batches of reaction materials is the same, the degree of heterogeneity and / or degree of polymerization of propylene monomer and α-olefin monomer in two-stage reactors with different aspect ratios and / or different volumes will also be different, so that more segments with different melting capabilities can be formed in the propylene / α-olefin copolymer; when the mass ratio of propylene monomer to α-olefin monomer in different batches of reaction materials is different, in two-stage reactors with the same aspect ratio and / or the same volume, the degree of heterogeneity and / or degree of polymerization of propylene monomer and α-olefin monomer will also be different, so that more segments with different melting capabilities can be formed in the propylene / α-olefin copolymer.

[0101] In some embodiments, the α-olefin monomer is selected from C2~C 20 At least one of the olefins.

[0102] Optionally, the α-olefin monomer is selected from one or more of ethylene, 1-butene, 1-pentene, 4-methyl-1-pentene, 1-hexene, 1-heptene, 1-octene, 1-decene, 1-undecene, 1-dodecene, 1-tetradecene, 1-hexadecene and 1-eicosene.

[0103] In some embodiments, in each batch of reaction materials, the mass proportion of α-olefin monomer in propylene monomer and α-olefin monomer is 5% to 25%.

[0104] In some embodiments, the catalyst may include a main catalyst and a co-catalyst.

[0105] The main catalyst may be a homogeneous catalyst, such as a metallocene catalyst or a non-metallocene catalyst.

[0106] Optionally, the main catalyst is selected from methylsilyl (N-tert-butylamino) (tetramethylcyclopentadienyl) titanium dichloride, dimethylsilyl (N-tert-butylamino) (tetramethylcyclopentadienyl) dimethyl titanium, dimethylsilyl (N-tert-butylamino) (fluorenyl) titanium dichloride, (pentamethylcyclopentadienyl) trimethoxytitanium, dibenzylidene (cyclopentadiene) (9-fluorenyl) zirconium dichloride, dimethyldisilyl bis (2-methyl-4-phenyl-1-indenyl) zirconium dichloride, mesodimethylsilyl bis (1-indenyl) zirconium dichloride, bis (methylcyclopentadiene) zirconium dichloride, rac-ethylene bis (1-indenyl) zirconium dichloride, bis (1,3-dimethylcyclopentadiene) The invention can be selected from the group consisting of (cyclopentadienyl) zirconium dichloride, (cyclopentadienyl) (1,2-dimethoxyethane) zirconium trichloride, diphenylsilyl (cyclopentadiene) (9-fluorenyl) zirconium dichloride, racemic dimethylsilyl bis (2-methyl-1-indenyl) zirconium dichloride, diphenylmethylenecyclopentadiene (2,7-di-tert-butyl-fluorenyl) zirconium dichloride, di-p-toluenemethylenecyclopentadiene (2,7-di-tert-butyl-fluorenyl) zirconium dichloride, dimethylbis (propylcyclopentadienyl) hafnium, bis (n-butylcyclopentadienyl) hafnium dichloride and dimethylsilyl bis (2-methyl-4-phenylindenyl) zirconium dichloride and one or more of the compounds represented by the following formulas (I) to (III).

[0107]

[0108] In some embodiments, the above-mentioned co-catalyst can be selected from one or more of aluminoxane, alkyl aluminum compound and alkyl aluminum chloride, or the co-catalyst can be a combination of one or more of aluminoxane, alkyl aluminum compound, alkyl aluminum chloride and one or more organic boron compounds; for example, the co-catalyst is a combination of aluminoxane and organic boron compound, a combination of alkyl aluminum compound and organic boron compound, or a combination of alkyl aluminum chloride and organic boron compound.

[0109] In some embodiments, the aluminoxane is selected from methylaluminoxane (MAO) and / or modified methylaluminoxane (MMAO).

[0110] In some embodiments, the alkyl aluminum compound is selected from at least one of triethylaluminum, triisobutylaluminum, and trioctylaluminum.

[0111] In some embodiments, the alkylaluminum chloride is selected from at least one of ethylaluminum monochloride, ethylaluminum sesquichloride and ethylaluminum dichloride.

[0112] In some embodiments, the organic boron compound is selected from at least one of trityltetrakis(pentafluorophenyl)borate, tris(pentafluorophenyl)boron, N,N-dimethylaniliniumtetrakis(pentafluorophenyl)borate, dioctadecylmethyltertiaryaminetetrakis(pentafluorophenyl)borate, and dihydrogenated tallow methyltertiaryaminetetrakis(pentafluorophenyl)borate.

[0113] In some embodiments, in each batch of reaction materials, the main catalyst and the co-catalyst are mixed in a certain ratio.

[0114] For example, in each batch of reaction materials, when the co-catalyst is selected from one or more of aluminoxane, alkyl aluminum compounds and alkyl aluminum chloride, the molar ratio Al / M of the metal aluminum element in the co-catalyst to the metal M element in the main catalyst can be 3~1000, for example, it can be 3, 5, 10, 20, 50, 80, 100, 120, 140, 160, 180, 200, 300, 400, 500, 600, 700, 800, 900 or 1000, optionally 10~200.

[0115] In some embodiments, when the co-catalyst comprises an organic boride, the molar ratio B / M of the organic boride (measured in boron) to the metal M element in the main catalyst is 0 to 10, for example, it can be 0, 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, 6, 7, 8, 9, 9.5 or 10, etc., and can be optionally 1 to 3.

[0116] In some embodiments, the above solvent is in liquid or supercritical state during the polymerization reaction, plays a role in mass transfer, and can be a hydrocarbon solvent.

[0117] For example, the hydrocarbon solvent may include: C5~C 12 At least one of aliphatic hydrocarbons of C6 to C8, aromatic hydrocarbons and dichloromethane. For example, the aliphatic hydrocarbon may be one or more of substituted or unsubstituted pentane, methylpentane, hexane, heptane, octane, cyclohexane, C6 mixed alkanes, methylcyclohexane and hydrogenated naphtha, wherein the substituent may be a C1 to C4 alkyl group; the aromatic hydrocarbon may be toluene, xylene, etc.

[0118] Optionally, the solvent is selected from at least one of hexane, C6 mixed alkanes, methylcyclohexane and Isopar E (mixed isomeric alkanes of C8-C10, purchased from Dow Chemical).

[0119] In some embodiments, each batch of reaction materials may also contain a chain transfer agent, such as hydrogen, etc. The chain transfer agent can adjust the molecular weight, reaction rate and molecular structure of the propylene / α-olefin copolymer, thereby obtaining a propylene / α-olefin copolymer that meets the requirements of chain length, melting peak temperature and melting range width.

[0120] In some embodiments, the temperature in each stage of the reactor is 80° C. to 220° C., and the pressure is 2 MPa to 10 MPa.

[0121] For example, the temperature in each stage of the reactor can be 80°C, 90°C, 100°C, 110°C, 120°C, 140°C, 150°C, 180°C, 200°C, 210°C or 220°C, and the pressure can be 2 MPa, 2.2 MPa, 2.5 MPa, 3.0 MPa, 3.5 MPa, 4.0 MPa, 4.5 MPa, 5.0 MPa, 5.5 MPa, 6 MPa, 7 MPa, 8 MPa, 9 MPa or 10 MPa, etc.

[0122] In some embodiments, the preparation method further includes: connecting a quenching kettle 13 to the reaction material outlet 112 of the last-stage reactor 11 of the reactor group, and connecting a devolatilization device 12 at the outlet of the quenching kettle 13, so as to use the quenching kettle 13 and the devolatilization device 12 to sequentially quench and devolatilize the propylene / α-olefin copolymer prepared in the last-stage reactor 11 to obtain a propylene / α-olefin copolymer.

[0123] In these embodiments, the propylene / α-olefin copolymer can be obtained by sequentially quenching and devolatilizing the polymerization product. In this process, quenching first and then devolatilizing can timely quench the catalyst activity remaining in the polymerization reaction liquid after the polymerization is completed, avoid the generation of polymer segments with high crystallinity in the subsequent devolatilization process, ensure that there is no high crystallinity peak in the propylene / α-olefin copolymer, so that dH(100) of the propylene / α-olefin copolymer is 0.

[0124] The quencher may be a mixed gas of a carrier gas and a reaction gas, wherein the carrier gas may include nitrogen and the reaction gas may include at least one of carbon monoxide and water vapor. The nitrogen plays a role of dilution and loading, and the reaction gas may deactivate the catalyst when it contacts the catalyst, thereby terminating the reaction.

[0125] In some embodiments, when the quencher is a mixed gas of nitrogen and carbon monoxide, the mass fraction of carbon monoxide is 1 wt% to 3wt%. When the quencher is a mixed gas of nitrogen and water vapor, the mass fraction of water vapor is 3% to 4%. When the quencher is a mixed gas of nitrogen, carbon monoxide and water vapor, the mass fraction of carbon monoxide is 0.5% to 1.5%, and the mass fraction of water vapor is 1.5% to 2.5%.

[0126] In a third aspect, some embodiments of the present application provide a use of the propylene / α-olefin copolymer as described in the first aspect in the preparation of a heat-sealing material.

[0127] In some embodiments, the propylene / α-olefin copolymer and the polypropylene material are mixed in a mass ratio of 1:(4-19), and a casting film is prepared by a casting process to prepare a heat-sealing material.

[0128] In these embodiments, a cast film with good tensile and impact properties can be obtained, and when the cast film is used for heat sealing, it has a lower heat sealing temperature and a wider heat sealing temperature range, which can effectively shorten the cooling and sealing time during the heat sealing process, and can reduce seal wrinkling and wire drawing, thereby reducing poor heat sealing.

[0129] In addition, since the melting peak number n(peak) of the propylene / α-olefin copolymer satisfies: 6≤n(peak)≤20, the segments with lower melting points in the multiple segments with different α-olefin insertion rates of the propylene / α-olefin copolymer can have a better toughening effect, and the segments with higher melting points in the multiple segments with different α-olefin insertion rates can increase the compatibility between the propylene / α-olefin copolymer and the base material such as polypropylene, and reduce the influence on the strength of the heat-sealing material, so the toughness and strength of the heat-sealing material can be effectively balanced. In summary, the heat-sealing material has good comprehensive properties.

[0130] The above introduces the specific implementation methods of the present application. In order to objectively illustrate the technical effects produced by the present application, the following embodiments and comparative examples will be used to illustrate the present application in detail.

[0131] In the following examples and comparative examples, all raw materials can be purchased in commercial form, and in order to maintain the reliability of the experiment, the raw materials used in the following examples and comparative examples have the same physical and chemical parameters or are processed in the same way.

[0132] Among them, the specific information of some materials and reagents is as follows:

[0133] 6102, propylene / ethylene copolymer, available from ExxonMobil;

[0134] 6202, propylene / ethylene copolymer, available from ExxonMobil;

[0135] F5606, terpolymer polypropylene, purchased from Yanshan Petrochemical;

[0136] Isopar-E, 100% hydrogenated naphtha, purchased from Mobil;

[0137] Ethylene, polymerization grade, purchased from Air Liquide;

[0138] Propylene, polymer grade, purchased from Air Liquide;

[0139] 1-Octene, 98%, purchased from INEOS;

[0140] 1-Hexene, 99%, purchased from Lingyan Biotechnology;

[0141] 1-Butene, 99%, purchased from Mingju;

[0142] rac-ethylenebis(1-indenyl)zirconium dichloride, 99%, strem, labeled M1;

[0143] Dimethylsilyl(N-tert-butylamino)(tetramethylcyclopentadienyl)dimethyltitanium, 99%, purchased from Sinoco, labeled as M2;

[0144] Dibenzylidenecyclopentadienyl (2,7-di-tert-butyl-fluorenyl) zirconium dichloride, 98%, purchased from Yaodexin Chemical, marked as M3;

[0145] MMAO, 7% aluminum solution, purchased from Nouryon;

[0146] MAO, 15% aluminum solution, purchased from Albemarle;

[0147] Triisobutylaluminum (TIBA) hexane solution, 1 mol / L, purchased from Inokai;

[0148] Trityl tetrakispentafluorophenyl borate, 99%, was purchased from Inotech and dissolved in toluene and marked as B1.

[0149] Example 1

[0150] Example 1 provides a method for preparing a propylene / α-olefin copolymer, the specific steps are as follows:

[0151] (1) Providing a reactor group comprising a two-stage reactor connected in series, a quenching tank and a devolatilization device, wherein the two-stage reactors are stirred tank reactors, the first-stage reactor has an aspect ratio of 2 and a volume of 1 L, and the second-stage reactor has an aspect ratio of 2 and a volume of 0.5 L;

[0152] (2) The first batch of reaction materials were introduced into the first reactor, wherein the α-olefin in the first batch of reaction materials was ethylene, the mass ratio of propylene to ethylene was 16:1, the main catalyst was M1, the addition amount was 20 μmol / h, the co-catalyst was MMAO, and the Al / M ratio was 500; the second batch of reaction materials were introduced into the second reactor, wherein the α-olefin in the second batch of reaction materials was ethylene, the mass ratio of propylene to α-olefin was 10:1, the main catalyst was M1, the addition amount was 20 μmol / h, the co-catalyst was MMAO, and the Al / M ratio was 500; the temperature in the first and second reactors was controlled to be 124°C, the pressure was 5 MPa, and the stirring speed was 700 r / min. After the reaction was completed, quenching, removal of volatile components, drying, extrusion and granulation were performed to obtain propylene / α-olefin copolymer particles. A mixed gas of nitrogen, carbon monoxide and water vapor was used as the quenching agent of the reaction, wherein the carbon monoxide concentration was 1wt% of the total mass of the mixed gas, and the water vapor concentration was 2wt% of the total mass of the mixed gas.

[0153] Example 2

[0154] The preparation method of the propylene / α-olefin copolymer provided in Example 2 is substantially the same as the preparation method of the propylene / α-olefin copolymer provided in Example 1, except that:

[0155] In step (1), in the two-stage reactor connected in series, the length-to-diameter ratio of the first-stage reactor is 1.5 and the volume is 2 L, and the length-to-diameter ratio of the second-stage reactor is 1.5 and the volume is 4 L;

[0156] In step (2), in the first batch of reaction materials, the mass ratio of propylene to ethylene is 16:1, the main catalyst is M2, the addition amount is 375 μmol / h, the co-catalyst is TIBA, Al / M is 5, and an organic boron compound type is B1, B / M is 3; in the second batch of reaction materials, the mass ratio of propylene to ethylene is 10:1, M2, the addition amount is 375 μmol / h, the co-catalyst is TIBA, Al / M is 5, and an organic boron compound type is B1, B / M is 3; the temperature in the first and second stage reactors is controlled to be 138°C, the pressure is 8 MPa, and the stirring speed is 700 r / min.

[0157] Example 3

[0158] The preparation method of the propylene / α-olefin copolymer provided in Example 3 is substantially the same as the preparation method of the propylene / α-olefin copolymer provided in Example 1, except that:

[0159] In step (1), in the two-stage reactor connected in series, the length-to-diameter ratio of the first-stage reactor is 1.5 and the volume is 2 L, and the length-to-diameter ratio of the second-stage reactor is 1.5 and the volume is 1 L;

[0160] In step (2), in the first batch of reaction materials, the α-olefin is 1-butene, the mass ratio of propylene to 1-butene is 10:1, the main catalyst is M3, the addition amount is 600 μmol / h, the co-catalyst is MAO, and the Al / M is 1000; in the second batch of reaction materials, the mass ratio of propylene to 1-butene is 10:1, the main catalyst is M3, the addition amount is 600 μmol / h, the co-catalyst is MAO, and the Al / M is 1000; the temperature in the first stage reactor and the second stage reactor are controlled to be 119°C, the pressure is 4 MPa, and the stirring speed is 700 r / min.

[0161] Example 4

[0162] The preparation method of the propylene / α-olefin copolymer provided in Example 4 is substantially the same as the preparation method of the propylene / α-olefin copolymer provided in Example 1, except that:

[0163] In step (1), in the two-stage reactor connected in series, the length-to-diameter ratio of the first-stage reactor is 1 and the volume is 3 L, and the length-to-diameter ratio of the second-stage reactor is 2 and the volume is 3 L;

[0164] In step (2), in the first batch of reaction materials, the α-olefin is 1-butene, the mass ratio of propylene to 1-butene is 10:1, the main catalyst is M2, the addition amount is 300 μmol / h, the co-catalyst is TIBA, Al / M is 3, and an organic boron compound type is B1, B / M is 1; in the second batch of reaction materials, the α-olefin is 1-butene, the mass ratio of propylene to 1-butene is 10:1, the main catalyst of propylene and 1-butene is M2, the addition amount is 300 μmol / h, the co-catalyst is TIBA, Al / M is 3, and an organic boron compound type is B1, B / M is 1; the temperature in the first stage reactor and the second stage reactor are controlled to be 120°C, the pressure is 6 MPa, and the stirring speed is 700 r / min.

[0165] Example 5

[0166] The preparation method of the propylene / α-olefin copolymer provided in Example 5 is substantially the same as the preparation method of the propylene / α-olefin copolymer provided in Example 1, except that:

[0167] In step (1), in the two-stage reactor connected in series, the length-to-diameter ratio of the first-stage reactor is 0.5 and the volume is 3 L, and the length-to-diameter ratio of the second-stage reactor is 1 and the volume is 6 L;

[0168] In step (2), in the first batch of reaction materials, the α-olefin is 1-octene, the mass ratio of propylene to 1-octene is 8:1, the main catalyst is M1, the addition amount is 500 μmol / h, the co-catalyst is MMAO, and Al / M is 50; in the second batch of reaction materials, the α-olefin is 1-octene, the mass ratio of propylene to 1-octene is 8:1, the main catalyst is M1, the addition amount is 500 μmol / h, the co-catalyst is MMAO, and Al / M is 50; the temperature in the first stage reactor and the second stage reactor are controlled to be 150°C, the pressure is 10 MPa, and the stirring speed is 700 r / min.

[0169] Comparative Example 1

[0170] The preparation method of the propylene / α-olefin copolymer provided in Comparative Example 1 is substantially the same as the preparation method of the propylene / α-olefin copolymer provided in Example 1, except that:

[0171] In step (1), in the two-stage reactors connected in series, the aspect ratio of the first-stage reactor and the second-stage reactor are both 5, and the volume is both 2L;

[0172] In step (2), in the first batch of reaction materials, the α-olefin is ethylene, the mass ratio of propylene to ethylene is 16:1, the main catalyst is M3, the addition amount is 400 μmol / h, the co-catalyst is MAO, and the Al / M is 1000; in the second batch of reaction materials, the α-olefin is ethylene, the mass ratio of propylene to ethylene is 10:1, the main catalyst is M3, the addition amount is 400 μmol / h, the co-catalyst is MAO, and the Al / M is 1000; the temperature in the first stage reactor and the second stage reactor are controlled to be 130°C, the pressure is 4 MPa, and the stirring speed is 700 r / min.

[0173] Comparative Example 2

[0174] The preparation method of the propylene / α-olefin copolymer provided in Comparative Example 2 is substantially the same as the preparation method of the propylene / α-olefin copolymer provided in Example 1, except that:

[0175] In step (1), in the two-stage reactors connected in series, the length-to-diameter ratio of the first-stage reactor and the second-stage reactor are both 5, the volume is both 2 L, and no quenching kettle is included;

[0176] In step (2), in the first batch of reaction materials, the α-olefin is ethylene, the mass ratio of propylene to ethylene is 16:1, the main catalyst is M3, the addition amount is 400 μmol / h, the co-catalyst is MAO, and the Al / M is 1000; in the second batch of reaction materials, the α-olefin is ethylene, the mass ratio of propylene to ethylene is 10:1, the main catalyst is M3, the addition amount is 400 μmol / h, the co-catalyst is MAO, and the Al / M is 1000; the temperature in the first stage reactor and the second stage reactor are controlled to be 130°C, the pressure is 4 MPa, and the stirring speed is 700 r / min, and devolatilization is directly carried out after the reaction is completed.

[0177] Comparative Example 3

[0178] Propylene / ethylene copolymer 6102 is commercially available.

[0179] Comparative Example 4

[0180] Propylene / ethylene copolymer 6202 is commercially available.

[0181] Test Case

[0182] The melting peak temperature Tm, melting range, n(peak), dH(100), density, Mw, PDI, MI (230°C, 2.16kg), glass transition temperature Tg, etc. of the propylene / α-olefin copolymers provided in Examples 1 to 5 and Comparative Examples 1 to 4 were tested, and the test results are shown in Tables 1 and 2 below.

[0183] Table 1

[0184]

[0185] Among them, in Table 1, the melting peak temperature T of the polymer is mThe melting enthalpy and melting enthalpy are tested by DSC, using the data obtained from the second heating, and the heating and cooling rates are 10 °C / min. The melting range is the temperature range between the temperature at which the polymer begins to melt and the temperature at which it is completely melted. n(peak) is measured by SSA of DSC, and the specific method is as follows: in the first cycle, the temperature is increased to 150°C, maintained for 1 minute, and decreased to -50°C; in the second cycle, the temperature is increased to 120°C, maintained for 5 minutes, and decreased to -50°C; in the third cycle, the temperature is increased to 112.5°C, maintained for 5 minutes, and decreased to -50°C; according to the above cyclic operation, the temperature is increased and maintained for 5 minutes and then cooled, and the fourth cycle (that is, when the temperature is increased in the fourth cycle, the temperature is increased at intervals of 7.5°C to a maximum point of 105°C and maintained for 5 minutes before cooling to -50°C), the fifth cycle (that is, when the temperature is increased in the fifth cycle, the temperature is increased at intervals of 7.5°C to a maximum point of 97.5°C and maintained for 5 minutes before cooling to -50°C), the sixth cycle..., until the heating temperature reaches -40°C, thereby crystallizing in each temperature interval. In the final cycle, the temperature was raised to 150°C at 10°C / min and the heat capacity change was measured. n(peak) represents the number of melting peaks during the final cycle and dH(100) represents the sum of the melting enthalpies above 100°C.

[0186] As can be seen from Table 1, the propylene / α-olefin copolymers provided in Examples 1 to 5 of the present application have a lower melting peak temperature, a larger melting range width, and their n(peak) can reach 7 to 18, and dH(100) is 0, which can effectively increase the insertion rate of α-olefin in the propylene / α-olefin copolymer, reduce the melting temperature of the propylene / α-olefin copolymer, and broaden the melting range of the propylene / α-olefin copolymer.

[0187] By comparing Examples 1 to 5 with Comparative Examples 1 to 4, it can be seen that by adjusting the aspect ratios and / or volumes of at least two reactors to be different from each other and controlling the aspect ratio of each reactor to be less than 3, a propylene / α-olefin copolymer having a low melting peak temperature, a large melting range width, a large number of melting peaks and a dH (100) of 0 can be obtained; at the same time, by comparing Comparative Example 1 with Comparative Example 2, it can be seen that timely quenching after the reaction is completed can avoid the generation of polymer segments with high crystallinity in the subsequent devolatilization process, so that the dH (100) of the propylene / α-olefin copolymer is 0.

[0188] Table 2

[0189]

[0190] Among them, in Table 2, the density is tested by a density meter: the sample to be tested is cut from a tablet plate, and the density is tested using a density meter MettlerXS204, using the immersion method, and the immersion liquid is anhydrous ethanol AR; the test environment temperature is 23℃±2℃, and the test temperature needs to be internally calibrated; the mass of the sample to be tested is >1g, and there are no bubbles; the mass of the sample in the air and the mass in the immersion liquid are weighed respectively, and the density of the propylene / α-olefin copolymer is calculated and derived by the Archimedes principle. The molecular weight, molecular weight distribution and insertion rate of α-olefin (such as ethylene) are obtained by GPC-IR test of polymer char, the test temperature is 150℃, and the product recovery rate exceeds 95%. The melt index (MI) test method under 230℃ and 2.16kg load conditions is as follows: take the mass of the pellet to be tested about 6g, set the temperature to 230℃, the load is 2.16kg, and the inner diameter of the standard die is 2.095mm. After the pellets are melted in the barrel for 5 minutes, they flow out of the die under the action of pressure load, and the time taken for the displacement point from 46mm to 20.6mm is measured and recorded. The sample strip is automatically cut and the mass of the sample strip is weighed on a balance. The MFR or MVR is calculated in g / 10min and cm 3 / 10min.

[0191] As can be seen from Table 2, the density, Mw, PDI, MI (230°C, 2.16 kg) and glass transition temperature of the propylene / α-olefin copolymers provided in Examples 1 to 5 of the present application are comparable to those of the propylene / α-olefin copolymers provided in Comparative Examples 1 to 4, and can meet the same application requirements as existing propylene / α-olefin copolymers.

[0192] Cast Film Example 1

[0193] The preparation method of the cast film in Cast Film Example 1 is as follows:

[0194] The propylene / α-olefin copolymer particles obtained in Example 1 were melt-blended with terpolymer polypropylene F5606 at a mass ratio of 1:9 in a casting machine and then cast. The casting temperature was 190° C. and the film thickness was controlled to be 40 μm.

[0195] Cast Film Example 2

[0196] The method for preparing the cast film in cast film embodiment 2 is substantially the same as the method for preparing the cast film in cast film embodiment 1, except that:

[0197] The propylene / α-olefin copolymer particles obtained in Example 2 were melt-blended with terpolymer polypropylene F5606 at a mass ratio of 1:9 in a casting machine and then cast.

[0198] Cast Film Example 3

[0199] The method for preparing the cast film in cast film example 3 is substantially the same as the method for preparing the cast film in cast film example 1, except that:

[0200] The propylene / α-olefin copolymer particles obtained in Example 3 were melt-blended with terpolymer polypropylene F5606 at a mass ratio of 1:9 in a casting machine and then cast.

[0201] Cast Film Example 4

[0202] The method for preparing the cast film in cast film example 4 is substantially the same as the method for preparing the cast film in cast film example 1, except that:

[0203] The propylene / α-olefin copolymer particles obtained in Example 4 were melt-blended with terpolymer polypropylene F5606 at a mass ratio of 1:9 in a casting machine and then cast.

[0204] Cast Film Example 5

[0205] The method for preparing the cast film in cast film example 5 is substantially the same as the method for preparing the cast film in cast film example 1, except that:

[0206] The propylene / α-olefin copolymer particles obtained in Example 5 were melt-blended with terpolymer polypropylene F5606 at a mass ratio of 1:9 in a casting machine and then cast.

[0207] Cast film comparative example 1

[0208] The preparation method of the cast film in cast film comparative example 1 is substantially the same as the preparation method of the cast film in cast film example 1, except that:

[0209] The propylene / α-olefin copolymer particles obtained in Comparative Example 1 were melt-blended with terpolymer polypropylene F5606 at a mass ratio of 1:9 in a casting machine and then cast.

[0210] Cast film comparative example 2

[0211] The preparation method of the cast film in cast film comparative example 2 is substantially the same as the preparation method of the cast film in cast film example 1, except that:

[0212] The propylene / α-olefin copolymer particles obtained in Comparative Example 2 were melt-blended with terpolymer polypropylene F5606 at a mass ratio of 1:9 in a casting machine and then cast.

[0213] Cast film comparative example 3

[0214] The preparation method of the cast film in cast film comparative example 3 is substantially the same as the preparation method of the cast film in cast film example 1, except that:

[0215] The propylene / α-olefin copolymer particles obtained in Comparative Example 3 were melt-blended with terpolymer polypropylene F5606 at a mass ratio of 1:9 in a casting machine and then cast.

[0216] Cast film comparative example 4

[0217] The preparation method of the cast film in cast film comparative example 4 is substantially the same as the preparation method of the cast film in cast film example 1, except that:

[0218] The propylene / α-olefin copolymer particles obtained in Comparative Example 4 were melt-blended with terpolymer polypropylene F5606 at a mass ratio of 1:9 in a casting machine and then cast.

[0219] Cast film comparative example 5

[0220] In the cast film comparative example 5, the cast film is cast only on the ternary copolymer polypropylene F5606 after melt blending in a casting machine.

[0221] Cast film test case

[0222] The tensile properties, dart impact properties, heat sealing temperature and heat sealing temperature range of the cast films obtained from cast film examples 1 to 5 and cast film comparative examples 1 to 5 were tested. Among them: the tensile properties were tested according to GB / T 13022-1991, the dart impact strength was tested according to ASTM D 1709, and the heat sealing temperature and heat sealing temperature range were tested according to GB / T-27740-2011 standard. The relevant test results are shown in Table 3.

[0223] Table 3

[0224]

[0225] As can be seen from Table 3, the cast film embodiments 1 to 5 of the present application have higher strength and toughness, as well as lower heat sealing temperature and larger melting range width. When applied to heat sealing films, they can shorten the cooling and sealing time, solve the problems of seal wrinkling and wire drawing existing in the related art, and improve the heat sealing yield.

[0226] By comparing Examples 1 to 5 and Comparative Examples 1 to 5, it can be seen that by adjusting the aspect ratio and / or volume of at least two reactors to be different from each other and controlling the aspect ratio of each reactor to be less than 3, a cast film with excellent tensile strength, dart impact strength and tensile elongation at break can be obtained, and the toughness of the cast film can be significantly improved while maintaining the high mechanical tensile strength of the cast film; at the same time, the heat sealing temperature of the cast film can be reduced, and the heat sealing temperature range can be widened, and the cast film has excellent performance.

[0227] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0228] The above-described embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be construed as limiting the scope of the patent application. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the patent application shall be subject to the attached claims.

Claims

1. A propylene / α-olefin copolymer, characterized in that: The melting peak temperature of the propylene / α-olefin copolymer is 40°C-90°C, the melting range width is 40°C-80°C, and the melting peak number n(peak) and dH(100) of the propylene / α-olefin copolymer satisfy: 6≤n(peak)≤20, dH(100)=0.

2. The propylene / α-olefin copolymer according to claim 1, characterized in that The propylene / α-olefin copolymer satisfies at least one of the following conditions: (1) The density of the propylene / α-olefin copolymer is 0.840 g / cm 3 ~0.880g / cm 3 ; (2) The weight average molecular weight of the propylene / α-olefin copolymer is 100,000 g / mol to 300,000 g / mol; (3) The molecular weight distribution width (PDI) of the propylene / α-olefin copolymer is 2.0 to 3.5; (4) The melting enthalpy of the propylene / α-olefin copolymer is 10 J / g to 100 J / g; (5) The melt index of the propylene / α-olefin copolymer at 230° C. and 2.16 kg load is 1.0 g / 10 min to 50.0 g / 10 min; (6) The glass transition temperature Tg of the propylene / α-olefin copolymer is -35°C to -15°C; (7) The α-olefin in the propylene / α-olefin copolymer is selected from C2 to C 20 At least one of the olefins; (8) The mass fraction of α-olefin in the propylene / α-olefin copolymer is 5% to 25%.

3. A method for preparing a propylene / α-olefin copolymer, characterized in that: include: A reactor group is provided, the reactor group comprising: a multi-stage reactor (11) connected in series, each stage of the reactor (11) having a reaction material inlet (111) and a reaction material outlet (112) arranged opposite to each other along the axial direction of the reactor (11), the reaction material outlet (112) of the previous stage reactor (11) being connected to the reaction material inlet (111) of the next stage reactor (11), the aspect ratio of each stage of the reactor (11) being less than or equal to 3, and at least two stages of the reactors (11) in the multi-stage reactor (11) having different aspect ratios and / or volumes; wherein the aspect ratio of each stage of the reactor (11) is equal to the ratio of a first dimension to a second dimension, the first dimension being the dimension between the reaction material inlet (111) and the reaction material outlet (112) of the reactor (11), and the second dimension being the radial dimension of the reactor (11); Controlling multiple batches of reaction materials to be respectively introduced into each stage of the reactor (11), and controlling different batches of the reaction materials to be polymerized with the reaction product of the previous stage reactor (11) in sequence in each stage of the reactor (11), so as to prepare the propylene / α-olefin copolymer; and The propylene / α-olefin copolymer prepared in the last stage reactor (11) is subjected to quenching and devolatilization treatment to obtain the propylene / α-olefin copolymer; Wherein, each batch of the reaction materials at least includes: propylene monomer, α-olefin monomer, solvent and catalyst.

4. The method for preparing a propylene / α-olefin copolymer according to claim 3, characterized in that: The length-to-diameter ratio of each stage reactor (11) is 0.5-3.

5. The method for preparing a propylene / α-olefin copolymer according to claim 3, characterized in that: The preparation method comprises: The stirring conditions, temperature and pressure in each stage of the reactor are controlled to be the same.

6. The method for preparing a propylene / α-olefin copolymer according to claim 3, characterized in that: The temperature in each stage of the reactor is 80°C to 220°C, and the pressure is 2MPa to 10MPa.

7. The method for preparing a propylene / α-olefin copolymer according to claim 3, characterized in that: The preparation method satisfies at least one of the following conditions: (1) The mass ratio of the propylene monomer to the α-olefin monomer in different batches of reaction materials is the same or different; (2) In each batch of reaction materials, the mass proportion of the α-olefin monomer in the propylene monomer and the α-olefin monomer is 5% to 25%; (3) The α-olefin monomer is selected from C2~C 20 At least one of the olefins.

8. The method for preparing a propylene / α-olefin copolymer according to claim 3, characterized in that: The preparation method further comprises: A quenching kettle (13) is connected to the reaction material outlet (112) of the last-stage reactor (11) of the reactor group, and a devolatilization device (12) is connected to the outlet of the quenching kettle (13), so that the propylene / α-olefin copolymer prepared in the last-stage reactor (11) is quenched and devolatilized in sequence by using the quenching kettle (13) and the devolatilization device (12) to obtain the propylene / α-olefin copolymer.

9. Use of the propylene / α-olefin copolymer according to any one of claims 1 to 2 in the preparation of heat-sealing materials.

10. The use according to claim 9, characterized in that: The propylene / α-olefin copolymer and the polypropylene material are mixed in a mass ratio of 1:(4-19), and a casting film is prepared by a casting process to prepare the heat sealing material.

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