Vinyl resin composition as well as preparation method and application thereof

Abstract

The invention provides a vinyl resin composition as well as a preparation method and application thereof. The vinyl resin composition comprises an ethylene homopolymer and an ethylene-butylene copolymer, and the weight ratio of the ethylene homopolymer to the ethylene-butylene copolymer is 1: (0.6-1.5); the short chain branching distribution factor (SCBI) of the vinyl resin composition is 0.02 to 0.04; the vinyl resin composition has a long chain branching index (LCBF) of 0.05 to 0.85. According to the present invention, the specific structure composition in the vinyl resin composition is controlled to promote the interpenetration of the crystalline structure and the non-crystalline structure, and the continuous molecular chain and the interlayer entanglement chain are used to connect the microcrystal, such that the resin cooling crystallization rate is uniform, the generation of the internal stress is reduced, and the molecular chain slippage possibility is reduced. Finally, the vinyl resin composition with good fluidity, dimensional stability, stress cracking resistance and processability is obtained.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of plastics, in particular to a vinyl resin composition, a preparation method and applications thereof. BACKGROUND

[0002] Injection molding can be used to manufacture plastic articles having relatively complex shapes, and is particularly suitable for manufacturing bottle cap articles for food or beverage applications, such as for bottles containing carbonated or non-carbonated beverages, or other non-food field applications, such as sealing cap articles for cosmetic and pharmaceutical containers. Bottle caps not only need to have the performance of keeping the content product airtight, but also need to have the function of security such as anti-theft opening, and are widely used in bottled products. Bottle cap material production is an upstream industry of food, beverage, wine, chemical industry, pharmaceutical industry, and is a key product of bottle container packaging.

[0003] Meanwhile, in today's industrial manufacturing field, especially in the packaging industry, polyethylene (PE) as a popular thermoplastic is widely used in various packaging products, such as bottle caps and closures for food, beverages, cosmetics and pharmaceutical products, due to its excellent physical and chemical properties, low cost and easy processability. In the injection molding process of polyethylene material, the molten polyethylene resin is injected into the mold under high pressure, and quickly cools and solidifies to form the final product. The high flowability of the resin is the key to achieving rapid mold filling, shortening the molding cycle and improving production efficiency, but this may sacrifice the mechanical strength and environmental stress cracking resistance of the product.

[0004] Therefore, for injection molded products such as bottle caps or closures, the polyethylene resin material required must find the best balance between high flowability, excellent dimensional stability and stress cracking resistance. This means that the polyethylene resin not only needs to ensure the processing efficiency during injection molding, but also needs to ensure that the bottle cap and other products can maintain good sealing performance and mechanical strength during long-term use, in order to avoid sealing failure due to creep or stress cracking.

[0005] Traditional high-density polyethylene (HDPE) resin, due to its fast crystallization rate, narrow molecular weight distribution, although has higher mechanical strength, but poor flowability, is not conducive to the rapid filling of injection molding process. Therefore, the development of a new polyethylene resin composition which has high flowability, and can ensure dimensional stability, stress cracking resistance and mechanical strength, has become an important research direction of the plastic packaging industry. CN108350098A provides a multimodal polyethylene composition and a screw cap comprising the same, the multimodal polyethylene composition comprises a low molecular weight component, a first ultrahigh molecular weight component and a second ultrahigh molecular weight component, and the relative molecular mass and crystallization properties are specified to meet the performance requirements. However, the excessive second ultrahigh molecular weight component provided by the technical scheme will bring lower exothermic melt index, produce higher content of high molecular weight component, and further bring the decline of processing performance. In addition, the short crystallization time of the resin composition will cause internal stress, which will seriously affect the stress cracking performance of the injection molded product. CN112839991A provides a polyethylene composition comprising a melt blend, which has a good balance between stiffness and processability, and can simultaneously achieve high stress cracking resistance in the cap and good processability during injection. However, the technical method does not consider the influence of short-chain branching and long-chain branching structure of the polyethylene composition on the environmental stress cracking (ESCR) performance, and the results of the disclosed examples also show that the ESCR performance of the resin composition disclosed in the technical scheme is insufficient, and the technical scheme does not consider the balance between processing performance and product dimensional stability. CN107207796A realizes the ideal balance of rheological properties, processing performance and mechanical properties of multimodal high-density polyethylene polymer through a specific combination of polymer design parameters (such as the ratio of lower relative molecular mass fraction and higher relative molecular mass fraction and its distribution, split between fractions, final MFR and density, etc.). However, in the technical scheme, although the low relative molecular mass component has very high melt index, it can ensure the good flowability of the resin composition, but loses its environmental stress cracking resistance. It can be clearly found from the disclosed examples that the ESCR performance of the resin composition is insufficient.

[0006] Therefore, how to provide a polyethylene resin composition which can simultaneously satisfy high flowability, dimensional stability, stress cracking resistance and good processing performance, so as to be used as an injection molding material and to prepare an injection molded product which meets various use requirements, is one of the important technical problems to be solved in the field. SUMMARY

[0007] The main objective of this invention is to provide a vinyl resin composition, its preparation method, and its application, in order to solve the problem that existing vinyl resin compositions for injection molding are difficult to simultaneously satisfy high fluidity, dimensional stability, stress cracking resistance, and good processing performance.

[0008] To achieve the above objectives, a first aspect of the present invention provides a vinyl resin composition comprising an ethylene homopolymer and an ethylene-butene copolymer, wherein the weight ratio of the ethylene homopolymer to the ethylene-butene copolymer is 1:(0.6 to 1.5); the vinyl resin composition has a short-chain branching distribution factor (SCBI) of 0.02 to 0.04; and the vinyl resin composition has a long-chain branching index (LCBF) of 0.05 to 0.85.

[0009] Further, the weight ratio of ethylene homopolymer to ethylene-butene copolymer is 1:(0.7 to 1.35); and / or, the short-chain branching distribution factor (SCBI) of the vinyl resin composition is 0.024 to 0.035; and / or, the long-chain branching index (LCBF) of the vinyl resin composition is 0.08 to 0.80.

[0010] Furthermore, the weight-average molecular weight M of the vinyl resin composition w Number-average molecular weight M n Satisfy: 10≤M w / M n ≤20, preferably 12≤M w / M n ≤20; and / or, the Z-average molecular weight M of the vinyl resin composition. z With Z+1 average molecular weight M z+1 Satisfy: 2.0≤M z+1 / M z ≤3.0, preferably 2.1≤M z+1 / M z ≤3.0; and / or, the Z-average molecular weight M of the vinyl resin composition. z With weight-average molecular weight M w Satisfy: 4.0≤M z / M w ≤5.5, preferably 4.5≤M z / M w ≤5.5.

[0011] Further, on the relative molecular mass distribution curve, the lg(M75) and the lg(M50) of the vinyl resin composition satisfy: 1.125 < lg(M75) / lg(M50) < 1.15, preferably 1.128 < lg(M75) / lg(M50) < 1.14; and / or, on the relative molecular mass distribution curve, the lg(M50) and the lg(M25) of the vinyl resin composition satisfy: 1.135 < lg(M50) / lg(M25) < 1.150, preferably 1.135 < lg(M50) / lg(M25) < 1.145.

[0012] Further, the density of the vinyl resin composition is 0.948 g / cm 3 ~ 0.957 g / cm 3 , preferably 0.950 g / cm 3 ~ 0.955 g / cm 3 ; and / or, the melt mass flow rate of the vinyl resin composition is 0.5 g / 10 min ~ 2.5 g / 10 min, preferably 1.0 g / 10 min ~ 2.2 g / 10 min, at 190°C under a load of 2.16 kg.

[0013] Further, the density of the ethylene homopolymer in the vinyl resin composition is 0.955 g / cm 3 ~ 0.960 g / cm 3 , preferably 0.956 g / cm 3 ~ 0.959 g / cm 3 ; and / or, the melt mass flow rate of the ethylene homopolymer in the vinyl resin composition is 10 g / 10 min ~ 50 g / 10 min, preferably 15 g / 10 min ~ 45 g / 10 min, at 190°C under a load of 2.16 kg.

[0014] Further, the notched impact strength of the vinyl resin composition is 15 kJ / m 2 ~ 25 kJ / m 2 , preferably 18 kJ / m 2 ~ 25 kJ / m 2 .

[0015] Further, the tensile yield stress of the vinyl resin composition is 15 MPa ~ 30 MPa, preferably 18 MPa ~ 25 MPa; and / or, the tensile fracture nominal strain of the vinyl resin composition is 400% ~ 550%, preferably 450% ~ 550%.

[0016] Further, the environmental stress cracking resistance time of the vinyl resin composition is 400h-750h, preferably 600h-750h; and / or, the tensile strain hardening value of the vinyl resin composition is 2.0-4.0, preferably 3.0-4.0.

[0017] Further, the vinyl resin composition is subjected to a full notched creep test, and the result is 30h-65h, preferably 40h-65h; and / or, the vinyl resin composition is subjected to a 1000 hour flex creep test at 23℃, 5.0MPa, and the deformation result is 0.7%-1.0%, preferably 0.7%-0.8%.

[0018] Further, the spiral flow length of the vinyl resin composition is 70cm-80cm, preferably 75cm-80cm, at 137.9MPa.

[0019] The second aspect of the present application provides a preparation method of the above-mentioned vinyl resin composition, comprising: step S1, ethylene is subjected to a first polymerization reaction with hydrogen to obtain an ethylene homopolymer; the feeding amount ratio of ethylene to hydrogen is 1kg / h:(1.0g / h-8.0g / h); step S2, the ethylene homopolymer, ethylene, hydrogen and 1-butene are subjected to a second polymerization reaction to form an ethylene-butene copolymer in the ethylene homopolymer, and further obtain the vinyl resin composition; the feeding amount ratio of ethylene, hydrogen and 1-butene is 1kg / h:(0.5g / h-2.5g / h):(100g / h-200g / h).

[0020] Further, the reaction temperature of the first polymerization reaction is 70℃-86℃, the reaction pressure is 0.1MPa-0.8MPa, and the reaction time is 10min-100min; and / or, the reaction temperature of the second polymerization reaction is 60℃-75℃, the reaction pressure is 0.1-0.6MPa, and the reaction time is 10min-100min.

[0021] Further, the reaction temperature of the first polymerization reaction is 72℃-85℃, the reaction pressure is 0.2MPa-0.6MPa, and the reaction time is 15min-40min; and / or, the reaction temperature of the second polymerization reaction is 62℃-73℃, the reaction pressure is 0.15MPa-0.50MPa, and the reaction time is 15min-25min.

[0022] Further, in step S1, the organic solvent used in the first polymerization reaction is selected from one or more of C3-C10 hydrocarbon solvents; preferably, the organic solvent is selected from one or more of pentane, hexane, heptane and octane, and more preferably hexane; further preferably, in step S1, the feeding amount ratio of ethylene to the organic solvent is 1:(1.8-2.4).

[0023] The third aspect of the present application provides the use of the above-mentioned vinyl resin composition as an injection molding plastic or compression molding plastic and the preparation of plastic products.

[0024] By controlling the specific structural composition of the vinyl resin composition, the mutual penetration of crystalline and non-crystalline structures in the vinyl resin composition is promoted, the microcrystals are connected by continuously existing molecular chains and interlayer entangled chains, the cooling crystallization rate of the resin is more uniform, the generation of internal stress is reduced, and the possibility of molecular chain slipping is reduced. At the same time, the short-chain branching distribution factor (SCBI) and the long-chain branching index (LCBF) of the resin composition are precisely controlled to exhibit certain strain hardening in elongational flow. Finally, a vinyl resin composition with good flowability, dimensional stability, stress cracking resistance and processing performance is obtained. DETAILED DESCRIPTION

[0025] It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other without conflict. The present application will be described in detail below with reference to the embodiments.

[0026] As described in the background, the injection molding vinyl resin composition in the prior art has the problem of being difficult to simultaneously satisfy high flowability, dimensional stability, stress cracking resistance and good processing performance. In order to solve the above technical problems, the first aspect of the present application provides a vinyl resin composition, which comprises an ethylene homopolymer and an ethylene-butene copolymer, and the weight ratio of the ethylene homopolymer to the ethylene-butene copolymer is 1:(0.6-1.5); the short-chain branching distribution factor SCBI of the vinyl resin composition is 0.02-0.04; and the long-chain branching index LCBF of the vinyl resin composition is 0.05-0.85.

[0027] It should be noted in advance that the infrared detector can provide short-chain branching (SCB) information of the polymer, with high sensitivity, high reliability and high precision. By equipping the GPC-IR5 high temperature gel permeation chromatography with an IR5 infrared detector, not only the relative molecular mass information of the resin composition can be obtained, but also the information of the short-chain branching structure molecular weight distribution, i.e. the distribution information of the thousand carbon short-chain branching number (SCB / 1000C) among the molecular chains. The short-chain branching distribution factor SCBI is calculated according to the following formula:

[0028]

[0029] wherein SCB(LogM=5.5) represents the short-chain branching number of the component with a molecular weight of 10 5.5 g / mol, and SCB(LogM=4.5) represents the short-chain branching number of the component with a molecular weight of 104.5 g / mol components, SCB (Log M > 5.5) represents the number of short chain branches of components with molecular weight exceeding 10 5.5 g / mol components, SCB (Log M > 5.5) represents the number of short chain branches of components with molecular weight exceeding 10

[0030] By using high temperature gel permeation chromatography (GPC-IR5-LS) equipped with light scattering detector, long chain branching (LCB) information of the resin composition can be obtained. The light scattering detector can provide molecular weight chain size information such as mean square radius of gyration of the polymer, with high sensitivity, high reliability and high precision. Combined with the information of molecular weight, information of mean square radius of gyration along the molecular weight distribution can be obtained. Long chain branching index (LCBF) is defined as g (Log M = 6.0), which represents the branching factor of components with molecular weight of 10 6 g / mol. Branching factor (g) is defined as the ratio between the mean square radius of gyration of the measured polymer and that of linear polyethylene, as shown in the following formula: g 2 g 2 L

[0031]

[0032] ε L represents the degree of tensile strain hardening of the resin composition, which is defined as:

[0033]

[0034] wherein η max is the maximum melt elongational viscosity measured at a certain elongation rate, and η L is the linear viscoelastic response viscosity value at the same time. For the purpose of the present patent, it is measured at a uniaxial elongation rate of 0.1 s -1 and a test temperature of 150°C.

[0035] The present application promotes the interpenetration of crystalline and non-crystalline structures in the ethylene-based resin composition by controlling the specific structural composition, connects the crystallites through the continuously existing molecular chains and interlayer entangled chains, so that the cooling crystallization rate of the resin is more uniform, the generation of internal stress is reduced, and the possibility of molecular chain slipping is reduced. At the same time, the short chain branching distribution factor (SCBI) and the long chain branching index (LCBF) of the resin composition are precisely controlled to exhibit certain strain hardening in elongational flow.

[0036] ​​​Specifically, the SCBI (short chain branching index) is controlled in the range of 0.02-0.04. The short chain branching, i.e. the formation of branches on the polymer chain, can increase the intermolecular interaction and reduce the crystallinity, thereby improving the flowability of the obtained resin in the molten state. However, the presence of branches can also affect the physical properties of the resin, such as tensile strength and creep resistance. By controlling the SCBI in the range of 0.02-0.04, the present application ensures both high flowability and sufficient mechanical strength and dimensional stability of the resin. The long chain branching, on the other hand, increases the complexity and entanglement of the molecular chains by forming longer branches on the polymer backbone, thereby improving the toughness and stress-cracking resistance of the material. At the same time, an appropriate amount of long chain branching can also improve the thermal stability of the resin by increasing the frictional resistance between molecules, which is particularly important for temperature control during injection molding. However, excessive long chain branching can significantly increase the melt viscosity of the resin, restricting its processing performance, especially the injection molding speed and efficiency. By controlling the LCBF in the range of 0.05-0.85, the present application ensures an appropriate amount of long chain branching, which helps to improve stress-cracking resistance while maintaining the processing performance of the resin.

[0037] In addition, based on the comprehensive consideration of the flowability and mechanical properties of the resin, the ratio of homopolymer to copolymer in the resin composition is set to 1:(0.6-1.5). Generally speaking, ethylene homopolymer, due to its regular structure and low branching degree, can impart high density and excellent mechanical strength to the resin, but the flowability is relatively poor. By adjusting the ratio of homopolymer to copolymer as above, the resin can have excellent flowability while maintaining sufficient mechanical strength, thereby achieving efficient mold filling and molding during injection molding.

[0038] In summary, by strictly controlling the specific structural composition of the ethylene-based resin composition and precisely controlling the short chain branching index (SCBI) and long chain branching index (LCBF) of the resin composition, an ethylene-based resin composition with good flowability, dimensional stability, stress-cracking resistance and processing performance is finally obtained.

[0039] In several more preferred embodiments, the weight ratio of the ethylene homopolymer to the ethylene-butene copolymer is 1:(0.7-1.35); and / or, the short chain branching index SCBI of the ethylene-based resin composition is 0.024-0.035; and / or, the long chain branching index LCBF of the ethylene-based resin composition is 0.08-0.80. Where the weight ratio of the homopolymer to the copolymer is set to be 1:(0.7-1.35), it helps to further enhance the dimensional stability of the material while maintaining high flowability. The SCBI in the range of 0.024-0.035 means that the distribution of short chain branching is more uniform, which helps to achieve faster filling speed during injection molding while maintaining the mechanical properties of the material after molding. The LCBF between 0.08-0.80 means that the degree of long chain branching of the several more preferred embodiments of the present application is more precisely adjusted, which helps to improve the stress cracking resistance while more significantly reducing the impact of high viscosity on the processing performance.

[0040] Further, the weight average molecular weight Mw of the ethylene-based resin composition w and the number average molecular weight Mn n satisfies: 10≤M w / M n ≤20; and / or, the Z average molecular weight Mz of the ethylene-based resin composition z and the Z+1 average molecular weight Mz+1 z+1 satisfies: 2.0≤M z+1 / M z ≤3.0; and / or, the Z average molecular weight Mz of the ethylene-based resin composition z and the weight average molecular weight Mw w satisfies: 4.0≤M z / M w ≤5.5; and / or, on the relative molecular mass integral distribution curve, the lg(M75) and the lg(M50) of the ethylene-based resin composition satisfy: 1.125≤lg(M75) / lg(M50)≤1.15; and / or, on the relative molecular mass integral distribution curve, the lg(M50) and the lg(M25) of the ethylene-based resin composition satisfy: 1.135≤lg(M50) / lg(M25)≤1.150.

[0041] A polymer is a long chain formed by the chemical linkage of repeating units (monomers). Polymers and low molecular weight compounds differ in that there is no fixed molecular weight, but rather a mixture of homologs of different molecular weights. Thus the molecular weight of a polymer is an average value, and the concept of a distribution exists. Chain length is usually expressed in terms of the molecular weight of the polymer chain, which is related to the relative molecular weight of the monomer and the number of monomers in the chain. However, all synthetic polymers have polydispersity, containing polymer chains of varying lengths, so the molecular weight of a polymer is not a single value - but rather a range of polymer chain lengths and molecular weights. Thus the molecular weight of a polymer must be described by calculating the average of the molecular weights of all the polymer chains in a sample.

[0042] M w is the weight average molecular weight, calculated by the formula M w =∑(N i ×M i 2 ) / ∑N i M i where N i is the number of polymer molecules of molecular weight M i in the sample. Relative to the number average molecular weight M n , M w takes into account the contribution of the size of the single chain molecular weight to M w . The greater the mass of the chain, the greater the contribution to M w .

[0043] M z is the Z average molecular weight, calculated by the formula M z =∑(N i ×M i 3 ) / ∑N i M i 2 is a method of calculating average molecular weight. M z+1 is the Z+1 average molecular weight, calculated by the formula M z+1 =∑(N i ×M i 4 ) / ∑N i M i 3 .

[0044] The distribution width index is the ratio of the relative molecular mass at I(M)=75%, I(M)=50% and I(M)=25% on the integral distribution curve of the relative molecular mass of the polymer. Three values of the relative molecular mass are taken on the curve: lg(M25), lg(M50) and lg(M75), the indices being the mass fraction. lg(M25) means that 25% of the mass of the sample has a relative molecular mass below M25; lg(M50) means that 50% of the mass of the sample has a relative molecular mass below M50; and lg(M75) means that 75% of the mass of the sample has a relative molecular mass below M75. The ratio lg(M75) / lg(M50) represents the distribution width of the high relative molecular mass fraction, and the ratio lg(M50) / lg(M25) represents the distribution width of the low relative molecular mass fraction.

[0045] However, the inventors have found, through extensive experiments, that when the molecular weight and distribution of the polyethylene-based resin composition provided by the present application are optimized to satisfy certain ranges, 1-butene is concentrated in the polymer structure of the high relative molecular mass main chain. In contrast, the more 1-butene is distributed in the high molecular weight ethylene, the more the stress cracking resistance of the resin composition can be improved. On this basis, the present application optimizes the M w (Mw / Mn) ratio (M n / M w ), the M n (Mz / Mn) ratio (M z / M w ), the M z (Mz+1 / Mn) ratio (M w / M z+1 ), the M z (Mz / Mw) ratio (M z+1 / M z ), the lg(M75) / lg(M50) ratio and the lg(M50) / lg(M25) ratio of these structural parameters more significantly balance the mechanical properties and stress cracking resistance of the obtained resin composition. Thus, the good performance of the polyethylene-based resin composition in environmental stress cracking resistance (ESCR) and full-notch creep test (FNCT) is further improved, while maintaining its dimensional stability and reducing creep.

[0046] Furthermore, the weight average molecular weight M w of the polyethylene-based resin composition and the number average molecular weight M n satisfy: 12≤M w / M n ≤20; and / or, the Z average molecular weight M z of the polyethylene-based resin composition and the Z+1 average molecular weight Mz+1 Satisfy: 2.1≤M z+1 / M z ≤3.0; and / or, the Z-average molecular weight M of the vinyl resin composition. z With weight-average molecular weight M w Satisfy: 4.5≤M z / M w ≤5.5; and / or, on the molecular weight integral distribution curve, lg(M75) and lg(M50) of the vinyl resin composition satisfy: 1.128≤lg(M75) / lg(M50)≤1.14; and / or, on the molecular weight integral distribution curve, lg(M50) and lg(M25) of the vinyl resin composition satisfy: 1.135≤lg(M50) / lg(M25)≤1.145. In the above scheme, M w / M n The range, i.e., 12 ≤ M w / M n ≤20 can more effectively balance the resin's flowability and mechanical properties, resulting in a resin that exhibits both good flowability and high mechanical strength during injection molding; M z / M w Preferably, 4.5≤M z / M w A value ≤5.5 can further enhance the resin's impact resistance and toughness; M z+1 / M z The preferred range is 2.1 ≤ M z+1 / M z A molecular weight of ≤3.0 indicates a wider molecular weight distribution, which helps the resin maintain better thermal stability at high temperatures. Furthermore, on the relative molecular mass integral distribution curve, by preferably setting 1.128≤lg(M75) / lg(M50)≤1.14 and / or 1.135≤lg(M50) / lg(M25)≤1.145, more precise control over the distribution of high and low molecular weight fractions can be achieved. This more effectively promotes the obtained vinyl resin composition to maintain flowability and processing properties while significantly enhancing dimensional stability and creep resistance, ultimately resulting in a resin composition with superior performance in all aspects.

[0047] Furthermore, in order to better balance the rigidity and flowability of the vinyl resin composition and obtain a resin composition with better processability and various post-molding properties, a density of 0.948 g / cm³ is preferred. 3 ~0.957g / cm 3 More preferably, it is 0.950 g / cm³. 3 ~0.955g / cm 3And, under the condition of 190°C, 2.16kg load, the melt mass flow rate of the ethylene-based resin composition is preferably 0.5g / 10min~2.5g / 10min, more preferably 1.0g / 10min~2.2g / 10min, which can not only promote the resin composition to fill the mold quickly during injection molding, but also reduce the mechanical property loss caused by too strong fluidity.

[0048] And, for the high-density ethylene homopolymer in the ethylene-based resin composition, in order to provide more sufficient rigidity to further enhance the strength of the resin composition after molding, the density thereof is preferably 0.955g / cm 3 ~0.960g / cm 3 , more preferably 0.956g / cm 3 ~0.959g / cm 3 And, in order to improve the fluidity of the resin composition, so that it can flow quickly during injection molding and optimize the processing performance, the melt mass flow rate of the ethylene homopolymer in the ethylene-based resin composition is preferably 10g / 10min~50g / 10min, more preferably 15g / 10min~45g / 10min, under the condition of 190°C, 2.16kg load.

[0049] In several preferred embodiments, the notched impact strength of the ethylene-based resin composition is 15kJ / m 2 ~25kJ / m 2 , preferably 18kJ / m 2 ~25kJ / m 2; and / or, the tensile yield stress of the vinyl resin composition is 15 MPa to 30 MPa, preferably 18 MPa to 25 MPa; and / or, the tensile strain at break of the vinyl resin composition is 400% to 550%, preferably 450% to 550%; and / or, the environmental stress crack resistance time of the vinyl resin composition is 400 h to 750 h, preferably 600 h to 750 h; and / or, the full notched creep test of the vinyl resin composition is 30 h to 65 h, preferably 40 h to 65 h; and / or, the flexural creep test of the vinyl resin composition at 23°C, 5.0 MPa for 1000 hours is 0.7% to 1.0%, preferably 0.7% to 0.8%; and / or, the tensile strain hardening value of the vinyl resin composition is 2.0 to 4.0, preferably 3.0 to 4.0; and / or, the spiral flow length of the vinyl resin composition at 137.9 MPa is 70 cm to 80 cm, preferably 75 cm to 80 cm. That is to say, the above-mentioned embodiments of the present application have achieved significant improvement in a plurality of key performance indicators, including but not limited to notched impact strength, tensile yield stress, tensile strain at break, environmental stress crack resistance time, full notched creep test time, flexural creep deformation, tensile strain hardening value, and spiral flow length.

[0050] The high notched impact strength means that the resin composition exhibits stronger toughness when impacted and is less likely to break in a brittle manner. This performance is mainly improved by long chain branching and optimized molecular weight distribution. The long chain branching increases the entanglement of molecular chains, improving the energy absorption capacity of the material, and the appropriate molecular weight distribution ensures the stress dispersion of the material when stressed, reducing the possibility of stress concentration, thereby enhancing the impact resistance of the material. The higher tensile yield stress means that the resin can withstand greater tensile force without plastic deformation. The higher tensile fracture nominal strain represents the resin that can withstand greater deformation in the tensile state without failure. This performance is also improved by moderate short chain branching and optimized molecular weight distribution, where short chain branching can increase the elasticity of the material, and the control of molecular weight distribution can help to improve the ductility of the material, both of which work together to improve the tensile fracture nominal strain of the material, making it less likely to be damaged when subjected to external tensile force. The high ESCR value means that the resin can maintain the integrity of its structure when exposed to harmful environments (such as solvents, acids and bases, ultraviolet light, etc.) for a long time, and is less likely to crack under stress; the higher FNCT value indicates that the resin is less likely to creep under continuous pressure; the low bending creep deformation means that the resin is less likely to permanently deform under bending stress. The three performances are also improved by the reasonable proportion distribution of the resin's homopolymer / copolymer and moderate long chain branching, and the microstructure can more effectively resist the long-term effect of stress. The high tensile strain hardening value, similarly, also comes from the control of long chain branching and appropriate molecular weight distribution, where long chain branching can increase the entanglement density of molecular chains, optimizing the stress transfer path; the appropriate proportion distribution of homopolymer / copolymer helps to improve the toughness of the material, both of which work together to improve the strain hardening capacity of the material during the stretching process. And the longer helical flow length means that the resin has better flowability. For injection molding process, a resin with good flowability can fill the mold faster, improving production efficiency.

[0051] In practical applications, the above-mentioned polyethylene resin composition provided by the present application can also add additives. The additives can be selected from antioxidants, ultraviolet absorbers, antistatic agents, slip agents, nucleating agents, etc., and are not limited to the above few.

[0052] Among the above-mentioned additives, the antioxidant is a compound that has the effect of preventing the decomposition of polyethylene resin due to heat, light, oxygen, etc., and can be specifically selected from phenolic antioxidants, phosphorus antioxidants, sulfur antioxidants, hydroxyl amine antioxidants, metal deactivators, etc., and is preferably a phenolic antioxidant, a phosphorus antioxidant or a sulfur antioxidant.

[0053] The phenol-based antioxidant can be specifically selected from 2,6-di-tert-butyl-4-methylphenol, tetrakis[methylene-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate]methane, pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], octadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, 3,9-bis[2-{3-(3-tert-butyl-4-hydroxy-5-methylphenyl)propionyloxy}-l,l-dimethylethyl]-2,4,8,10-tetraoxaspiro[5.5]undecane, l,3,5-tris-2-[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyloxy]ethyl isocyanurate, l,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)benzene, tris(3,5-di-tert-butyl-4-hydroxybenzyl)isocyanurate, l,3,5-tris(4-tert-butyl-3-hydroxy-2,6-dimethylbenzyl)isocyanurate, pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], triethylene glycol-bis-3-(3-tert-butyl-5-methyl-4-hydroxyphenyl)propionate, l,6-hexanediol bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], 2,2'-dithio-bis-ethylene-bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], 2,2'-methylene-bis-(4-methyl-6-tert-butylphenol), 2,2'-methylene-bis-(4-ethyl-6-tert-butylphenol), 2,2'-methylene-bis-(4,6-di-tert-butylphenol), 2,2'-ethylidene-bis-(4,6-di-tert-butylphenol), 2,2'-butylidene-bis-(4-methyl-6-tert-butylphenol), 4,4'-butylidene-bis(3-methyl-6-tert-butylphenol), 2-tert-butyl-6-(3-tert-butyl-2-hydroxy-5-methylbenzyl)-4-methylphenyl acrylate, 2,4-di-tert-amyl-6-(l-(3,5-di-tert-amyl-2-hydroxyphenyl)ethyl)phenyl acrylate, tocopherols, and the like.

[0054] When the phenol-based antioxidant is added, the content thereof is usually 0.01 to 2 parts by weight, and preferably 0.01 to 0.5 parts by weight, relative to 100 parts by weight of the polyvinyl resin composition.

[0055] The phosphorus-based antioxidant can be specifically selected from the group consisting of tris(nonylphenyl) phosphite, tris(2,4-di-tert-butylphenyl) phosphite, distearyl pentaerythritol diphosphite, bis(2,4-di-tert-butylphenyl) pentaerythritol diphosphite, bis(2,4-di-tert-butyl-6-methylphenyl) pentaerythritol diphosphite, bis(2,6-di-tert-butyl-4-methylphenyl) pentaerythritol diphosphite, bis(2,4-dicumylphenyl) pentaerythritol diphosphite, tetrakis(2,4-di-tert-butylphenyl)-4,4'-diphenylene diphosphonite, 2,2'-methylenebis(4,6-di-tert-butylphenyl) 2-ethylhexyl phosphite, 2,2'-ethylidenebis(4,6-di-tert-butylphenyl) fluorophosphite, bis(2,4-di-tert-butyl-6-methylphenyl) ethyl phosphite, 2-(2,4,6-tri-tert-butylphenyl)-5-ethyl-5-butyl-1,3,2-dioxaphosphocin, 2,2',2"-nitrilo[triethyl-tris(3,3',5,5'-tetra-tert-butyl-1,1'-biphenyl-2,2'-diyl) phosphite, 2,4,8,10-tetra-tert-butyl-6-[3-(3-methyl-4-hydroxy-5-tert-butylphenyl)propoxy]dibenz[d,f][1,3,2] dioxaphosphepin, and the like. Tris(2,4-di-tert-butylphenyl) phosphite or 2,4,8,10-tetra-tert-butyl-6-[3-(3-methyl-4-hydroxy-5-tert-butylphenyl)propoxy]dibenz[d,f][1,3,2] dioxaphosphepin is preferred.

[0056] When the phosphorus-based antioxidant is added, the content thereof is generally 0.01 to 2 parts by weight, preferably 0.01 to 0.5 parts by weight, relative to 100 parts by weight of the polyethylene resin composition.

[0057] The sulfur-based antioxidant can be specifically selected from the group consisting of dilauryl 3,3'-thiodipropionate, tridecyl 3,3'-thiodipropionate, dimyristyl 3,3'-thiodipropionate, distearyl 3,3'-thiodipropionate, lauryl stearyl 3,3'-thiodipropionate, pentaerythritol tetrakis(3-laurylthiopropionate), bis[2-methyl-4-(3-n-alkyl(C12-C14)thiopropionyloxy)-5-tert-butylphenyl] sulfide, and the like. Distearoyl 3,3'-thiodipropionate, dimyristyl 3,3'-thiodipropionate, or distearyl 3,3'-thiodipropionate is preferred.

[0058] When the sulfur-based antioxidant is added, the amount thereof is generally 0.01 to 2 parts by weight, preferably 0.01 to 0.5 parts by weight, relative to 100 parts by weight of the polyethylene resin composition.

[0059] In the present application, a slip agent can be used together with the resulting polyvinyl resin composition so as to facilitate easy sliding between the resin compositions when they come into contact with each other, thereby facilitating industrial operations. Specifically, the slip agent can be selected from various known aliphatic acid amide compounds, particularly saturated aliphatic acid amides, unsaturated aliphatic acid bisamides, etc. Among them, the saturated aliphatic acid amide is selected from palmitamide, stearamide, behenamide, etc., with behenamide being preferred; the unsaturated aliphatic acid amide is selected from oleamide, erucamide, etc., with erucamide being preferred; the saturated aliphatic acid bisamide is selected from ethylene bispalmitamide, ethylene bisstearamide, hexamethylene bisstearamide, etc., with ethylene bisstearamide being preferred; and the unsaturated aliphatic acid bisamide is selected from ethylene bisoleamide, hexamethylene bisoleamide, N,N"-dioleyl sebacamide, etc., with ethylene bisoleamide being preferred.

[0060] In practice, two or more of the above-described slip agents can be used together in actual applications. When two or more slip agents are used together, a complex composed of an unsaturated aliphatic acid amide and a saturated or unsaturated aliphatic acid bisamide is preferably used. The content of the slip agent is generally 0.05 to 0.35 parts by weight, preferably 0.1 to 0.25 parts by weight, relative to 100 parts by weight of the polyvinyl resin composition.

[0061] A second aspect of the present application provides a method for preparing the above-described polyvinyl resin composition, comprising: Step S1, first polymerization of ethylene with hydrogen to obtain an ethylene homopolymer; the ratio of the feed amounts of ethylene and hydrogen is 1 kg / h : (1.0 g / h to 8.0 g / h), preferably 1 kg / h : (2.0 g / h to 6.0 g / h); Step S2, second polymerization of the ethylene homopolymer, ethylene, hydrogen, and 1-butene to form an ethylene-butene copolymer in the ethylene homopolymer, thereby obtaining the polyvinyl resin composition; the ratio of the feed amounts of ethylene, hydrogen, and 1-butene is 1 kg / h : (0.5 g / h to 2.5 g / h) : (100 g / h to 200 g / h), preferably 1 kg / h : (0.8 g / h to 1.2 g / h) : (100 g / h to 200 g / h).

[0062] For the above-mentioned ethylene-based resin composition, the present application correspondingly provides a preparation method thereof. The final resin composition is obtained by first preparing an ethylene homopolymer and then further forming an ethylene-butene copolymer through a two-step polymerization reaction, so as to effectively control the distribution of short-chain branching and long-chain branching, and further realize the superior comprehensive performance of the obtained resin composition. In step S1 and step S2, by gradually adjusting the feed ratio of hydrogen to ethylene, the molecular weight can be effectively controlled, and then the flowability and mechanical properties of the resin are affected. Specifically, for the above-mentioned resin composition of the present application, in the first polymerization reaction, a lower hydrogen ratio is conducive to the formation of a homopolymer with a higher molecular weight, which will improve the toughness of the material; and in the second polymerization reaction, a reasonable ratio of hydrogen to 1-butene helps to introduce an appropriate amount of short-chain branching, thereby enhancing the stress cracking resistance and dimensional stability of the material.

[0063] And in step S2, the obtained ethylene homopolymer is reacted with ethylene, hydrogen and 1-butene to form a copolymer with a high molecular weight. In this process, by gradually optimizing the ratio of the feed amounts of ethylene, hydrogen and 1-butene, a more appropriate amount of comonomer can be introduced. Thus, a structure of crystalline and non-crystalline interpenetrating each other is formed between the homopolymer that has been formed, and the microcrystals are connected by continuously existing molecular chains and interlayer entangled chains, so that the cooling crystallization rate of the resin is more uniform, the generation of internal stress is reduced, and the possibility of molecular chain slipping is reduced, thereby significantly increasing the toughness and stress cracking resistance of the material, while maintaining good dimensional stability and mechanical properties.

[0064] In general, by synergistically controlling the feed ratio of hydrogen to ethylene and the addition of 1-butene in the above preparation process, the molecular chain structure and molecular weight distribution of the resin composition are precisely controlled, and the performance of the resin composition is significantly improved.

[0065] In several typical embodiments, the reaction temperature of the first polymerization reaction is 70°C to 86°C, the reaction pressure is 0.1 MPa to 0.8 MPa, and the reaction time is 10 min to 100 min; and / or, the reaction temperature of the second polymerization reaction is 60°C to 75°C, the reaction pressure is 0.1 to 0.6 MPa, and the reaction time is 10 min to 100 min. By adjusting the above reaction conditions, the molecular chain structure can be more effectively made to have a certain flowability while also having high mechanical strength and durability. At the same time, the above reaction conditions also help to further optimize the molecular weight distribution and reduce the negative impact of excessively long or short molecular chains on the performance of the material.

[0066] In several more typical embodiments, the first polymerization reaction preferably has a reaction temperature of 72°C to 85°C, a reaction pressure of 0.2 MPa to 0.6 MPa, and a reaction time of 15 min to 40 min; and / or, the second polymerization reaction preferably has a reaction temperature of 62°C to 73°C, a reaction pressure of 0.15 MPa to 0.50 MPa, and a reaction time of 15 min to 25 min, so as to favor the introduction of a more suitable amount of 1-butene. In particular, when the temperature in this process is too high, it can accelerate the chain termination reaction, reduce the molecular weight and the degree of branching, while too low a temperature can result in insufficient branching reaction, affecting the toughness of the material. When the polymerization time of the second polymerization reaction is too long, it will promote the formation of branches on the polymer chain by ethylene and 1-butene in the reaction system, and excessive branching will increase the entanglement and crosslinking between molecular chains, causing the internal stress of the resin to increase, reducing its creep resistance. When the polymerization time is too short, the polymerization reaction can not reach the kinetic equilibrium, resulting in uneven distribution of molecular weight and branching degree, affecting its various properties; at the same time, too short polymerization time can result in incomplete conversion of monomers to polymer chains, and the residual monomers will increase the odor of the resin, affecting its use experience.

[0067] However, the inventors have found through extensive experiments that the first polymerization reaction preferably has a reaction temperature of 78°C to 84°C, a reaction pressure of 0.3 MPa to 0.5 MPa, and a reaction time of 20 min to 30 min; and / or, the second polymerization reaction preferably has a reaction temperature of 68°C to 72°C, a reaction pressure of 0.20 MPa to 0.40 MPa, and a reaction time of 18 min to 22 min. In the above scheme, since the formation of ethylene homopolymer is less dependent on the branching reaction which is sensitive to temperature, but focuses on the chain growth reaction, the first polymerization reaction can more effectively control the molecular weight under the above conditions, keeping the melt flow rate (MFR) of the resin composition at a moderate level, and preparing an ethylene homopolymer with higher flowability. In the second polymerization reaction, the preferred temperature and pressure conditions can more effectively control the insertion of 1-butene in the copolymer, i.e., further optimize the number and distribution of short chain branching (SCB), more significantly reduce the formation and expansion of cracks in the obtained resin composition under stress, thereby improving its environmental stress cracking resistance.

[0068] In step S1, the organic solvent used in the first polymerization reaction is preferably selected from one or more of C3-C10 hydrocarbon solvents, preferably selected from one or more of pentane, hexane, heptane and octane, and more preferably hexane. The above hydrocarbon solvents, especially hexane, have good solubility and low reactivity, which can maintain the solubility of ethylene and 1-butene in the polymerization reaction, reduce precipitation, increase the probability of collision between monomers, improve the uniformity of the polymerization reaction, help to form a resin composition with uniform molecular weight distribution and composition, and at the same time reduce the residual stress in the product, reduce the risk of creep and stress cracking during long-term use.

[0069] In several typical embodiments, the ratio of the feed amount of ethylene to the organic solvent in step S1 is preferably 1:(1.8-2.4), so as to more effectively maintain the fluidity of the system, make the polymerization reaction more uniform, and facilitate the formation of a resin composition with more uniform molecular weight distribution and more moderate branching degree, thereby more significantly improving the performance thereof.

[0070] In practical applications, the above resin composition provided by the present application can be prepared by a sequential polymerization method, which is realized by a system comprising at least two reactors connected in series, i.e., a first reactor and a second reactor. The reaction mixture in the first reactor (i.e., the first ethylene homopolymer component and unreacted monomers) is preferably transported, preferably directly transported, into the second reactor in which the second ethylene copolymer component is obtained.

[0071] Generally, the reactors are usually selected from slurry reactors and gas phase reactors. More specifically, the first reactor is preferably a first slurry reactor, and can be any continuous or simply stirred batch tank reactor or loop reactor carried out by bulk polymerization or slurry polymerization. The second reactor is preferably a second slurry reactor. The polymerization in the second reactor step is followed by conventional post-reactor treatment to remove unreacted components to obtain a polyethylene resin composition.

[0072] In the above reaction system, the possible subsequent one or more polymerization reactors are preferably slurry reactors.

[0073] In addition, the above two-step polymerization reaction is carried out in the presence of an olefin polymerization catalyst. The catalyst can be any catalyst capable of preparing the desired ethylene polymer. Suitable catalysts are transition metal-based Ziegler-Natta (Z-N) catalysts, including titanium catalysts, zirconium catalysts and / or vanadium catalysts. The present application preferably uses Ziegler-Natta (Z-N) catalysts, and the Ziegler-Natta (Z-N) catalysts include magnesium compounds, aluminum compounds and titanium compounds, optionally supported on a carrier.

[0074] The carrier can be an inorganic oxide carrier such as silicon dioxide, aluminum oxide, titanium dioxide, silicon dioxide-aluminum oxide and silicon dioxide-titanium dioxide. Preferably, the carrier is silicon dioxide. The magnesium compound is at least one selected from the group consisting of magnesium chloride, magnesium bromide, methylmagnesium chloride, diethylmagnesium chloride, diisopropylmagnesium chloride, dibutylmagnesium chloride, dioctylmagnesium chloride, diethylmagnesium, dipropylmagnesium, dibutylmagnesium, dioctylmagnesium, isopropylmagnesium, butylmagnesium, butyl-octylmagnesium, n-octylmagnesium and 2-ethylhexylmagnesium. The aluminum compound is at least one selected from the group consisting of triethylaluminum, diethylaluminum chloride, monoethylaluminum dichloride, ethylaluminum sesquichloride, isobutylaluminum dichloride, triisobutylaluminum, diisopropylaluminum chloride, methyl-n-propylaluminum chloride and diphenylaluminum chloride. The titanium compound is a halogen-containing titanium compound selected from at least one of titanium tetrachloride, titanium tetrabromide, titanium tetraiodide, titanium tetrabutoxide, titanium tetraethoxide, titanium trichloride, titanium dichloride, titanium diethoxide and titanium monoethoxide. The preferred titanium compound is titanium tetrachloride. The catalyst can be prepared by sequentially contacting the carrier with the above compounds. Alternatively, it can be prepared by first preparing solutions from each component and then contacting the solutions with the carrier.

[0075] In actual polymerization processes, the Ziegler-Natta catalyst (Z-N) is used together with an activator. Suitable activators are metal alkyl compounds, and in particular aluminum alkyl compounds. The activator is used as a cocatalyst. These compounds include alkyl aluminum halides such as ethyl aluminum dichloride, diethyl aluminum chloride, ethyl aluminum sesquichloride, dimethyl aluminum chloride, and the like. They also include trialkyl aluminum compounds such as trimethyl aluminum, triethyl aluminum, triisobutyl aluminum, trihexyl aluminum, and tri-n-octyl aluminum. In addition, they include alkyl aluminum oxides such as methyl aluminoxane (MAO), hexaisobutyl aluminoxane (HIBAO), and tetraisobutyl aluminoxane (TIBAO). Other alkyl aluminum compounds such as isobutyl isoamyl aluminum can also be used. The preferred activators are trialkyl aluminum, with triethyl aluminum, trimethyl aluminum, and triisobutyl aluminum being particularly preferred. The amount of activator used depends on the particular catalyst and activator. Typically, triethyl aluminum is used in an amount such that the molar ratio of aluminum to transition metal (e.g., Al / Ti) is 3 to 300 mol / mol, preferably 5 to 50 mol / mol.

[0076] A third aspect of the present application provides the use of the above-described vinyl resin composition as a plastic for injection molding or compression molding and the production of plastic articles. The above-described vinyl resin composition provided by the present application can be used to form any molded article by precisely controlling the content ratio of the copolymer / homopolymer, the molecular weight distribution, the degree of long-chain and short-chain branching, and the optimized processing properties. Further, the present application relates to injection-molded or compression-molded articles.

[0077] Further, the present application provides a process for the production of injection or compression molded articles comprising injection or compression molding the polyethylene resin composition into an article, and use of the polyethylene composition for injection or compression molding.

[0078] Among them, injection molded articles including containers such as bottles, caps and closures, transport packaging such as boxes, baskets, cabinets, etc., household utensils such as buckets, food containers and water pools, and thin-walled packaging articles such as open plastic containers for frozen or fresh food, have advantages in the application of various fields, meeting the diversified needs of material performance in different industries.

[0079] The present application will be further described in conjunction with specific examples, which cannot be understood as limiting the scope of the present application.

[0080] Unless otherwise defined, all the professional terms used below have the same meaning as generally understood by those skilled in the art. The professional terms used herein are only for the purpose of describing specific examples and are not intended to limit the scope of protection of the present application.

[0081] Before the preparation of the ethylene-based resin composition, the present application provides a method for preparing the catalyst used as follows:

[0082] In a reactor which has been sufficiently replaced with high-purity nitrogen, 90 kg of toluene is added. Then, 50 kg of a heptane solution of butyl octyl magnesium is added to the reactor. Then, 160 kg of 99.9% 2-ethyl-1-hexanol is introduced into the reactor at a flow rate of 20 kg / h to form a complex. The molar ratio of butyl octyl magnesium to 2-ethyl-1-hexanol is 1:1.8. 300 kg of silica which has been activated at 600°C in nitrogen is charged into a catalyst preparation reactor. At room temperature, 400 kg of 20% silica diluted in 600 liters of pentane is added to the reactor within 1 hour. Then, the temperature is raised to 40°C and the treated silica is stirred for 1.5 hours. The silica is dried at 50°C for 10 hours. Then, 670 kg of the complex prepared as above is added at 25°C within 10 minutes. 90 kg of pentane is added to the reactor at 25°C within 10 minutes. The slurry is stirred at 50°C for 10 hours. Finally, 56 kg of TiCl4 is added at 50°C within 0.5 hour. The slurry is stirred at 40°C for 5 hours. Then, it is dried by purging with nitrogen to obtain the catalyst.

[0083] Example 1

[0084] A method for preparing an ethylene-based resin composition is carried out in a continuous process in two slurry reactors connected in series, and the specific steps are as follows.

[0085] (1) The Z-N catalyst prepared by the above method is continuously fed into the first reactor at a feed rate of 15.1 mmol / h, the co-catalyst (triethylaluminum) is continuously fed into the first reactor at a feed rate of 150 mmol / h, the ethylene feed rate is 80 kg / h, and the hydrogen feed rate is 80 g / h (i.e., the ratio of the ethylene feed rate to the hydrogen feed rate is 1 kg / h: 1 g / h) to complete the first-stage ethylene homopolymerization reaction to obtain a first ethylene polymer. The polymerization reaction temperature in the first reactor is 70°C, the reaction pressure is 0.8 MPa, and the reaction time is 100 min. The hydrogen added in the feed of the first reactor is used as a molecular weight regulator, and hexane is used as a solvent, and the feed rate is 150 kg / h (i.e., the ratio of the ethylene feed rate to the organic solvent feed rate is 1:1.88).

[0086] (2) The ethylene homopolymer-containing stream obtained from the first reactor is fed into the second reactor. The polymerization reaction temperature in the second reactor is 60°C, the reaction pressure is 0.6 MPa, and the reaction time is 100 min. In the feed of the second reactor, the ethylene feed rate is 80 kg / h, the hydrogen feed rate is 40 g / h, and the comonomer 1-butene is added at a rate of 16000 g / h (i.e., the ratio of the ethylene feed rate to the hydrogen feed rate to the comonomer 1-butene feed rate is 1 kg / h: 0.5 g / h: 200 g / h) to obtain an ethylene-butene copolymer. The solvent is separated from the slurry discharged from the second reactor and dried to obtain the final polymer powder.

[0087] (3) The obtained polymerization product is subjected to wet nitrogen to remove unreacted catalyst activity and heated and dried to obtain a polymer powder. The polymer powder is mixed with an antioxidant, tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate]pentaerythritol ester 0.1%, and tris(2,4-di-tert-butylphenyl)phosphite 0.1%, melt-extruded and granulated to obtain a multimodal ethylene-based resin composition. The addition amount of both antioxidants is based on the total weight of the resin composition being 100%.

[0088] Example 2

[0089] A method for preparing an ethylene-based resin composition is carried out in a continuous manner in two slurry reactors connected in series, and the specific steps are as follows.

[0090] (1) The Z-N catalyst prepared in the above method is continuously fed into the first reactor at a feed rate of 15.1 mmol / h, the co-catalyst (triethylaluminum) is continuously fed into the first reactor at a feed rate of 150 mmol / h, the ethylene feed rate is 80 kg / h, and the hydrogen feed rate is 480 g / h (i.e., the ratio of the ethylene feed rate to the hydrogen feed rate is 1 kg / h:6.0 g / h) to complete the first-stage ethylene homopolymerization to obtain a first ethylene polymer; the polymerization temperature in the first reactor is 86°C, the reaction pressure is 0.1 MPa, and the reaction time is 10 min. The hydrogen added in the feed of the first reactor is used as a molecular weight regulator, and the hexane is used as a solvent, and the feed rate is 150 kg / h (i.e., the ratio of the ethylene feed rate to the organic solvent feed rate is 1:1.88).

[0091] (2) The ethylene homopolymer-containing stream obtained in the first reactor is fed into the second reactor; the polymerization temperature in the second reactor is 75°C, the reaction pressure is 0.1 MPa, and the reaction time is 10 min. In the feed of the second reactor, the ethylene feed rate is 75 kg / h, the hydrogen feed rate is 90 g / h, and the comonomer 1-butene is added at a rate of 7500 g / h (i.e., the ratio of the ethylene feed rate to the hydrogen feed rate to the comonomer 1-butene feed rate is 1 kg / h:1.2 g / h:100 g / h); an ethylene-butene copolymer is obtained. The solvent is separated from the slurry discharged from the second reactor and dried to obtain the final polymer powder.

[0092] (3) This step is consistent with Example 1.

[0093] Example 3

[0094] A method for preparing an ethylene-based resin composition is performed in a continuous manner in two slurry reactors connected in series, and the specific steps are as follows.

[0095] (1) The Z-N catalyst prepared in the above method is continuously fed into the first reactor at a feed rate of 15.1 mmol / h, the co-catalyst (triethylaluminum) is continuously fed into the first reactor at a feed rate of 150 mmol / h, the ethylene feed rate is 80 kg / h, and the hydrogen feed rate is 160 g / h (i.e., the ratio of the ethylene feed rate to the hydrogen feed rate is 1 kg / h:2.0 g / h) to complete the first-stage ethylene homopolymerization to obtain a first ethylene polymer; the polymerization temperature in the first reactor is 82°C, the reaction pressure is 0.3 MPa, and the reaction time is 30 min. The hydrogen added in the feed of the first reactor is used as a molecular weight regulator, and the hexane is used as a solvent, and the feed rate is 150 kg / h (i.e., the ratio of the ethylene feed rate to the organic solvent feed rate is 1:1.88).

[0096] (2) The stream containing the ethylene homopolymer from the first reactor is fed into the second reactor; the polymerization temperature in the second reactor is 68°C, the reaction pressure is 0.4 MPa, and the reaction time is 18 min. In the feed to the second reactor, the ethylene feed rate is 77 kg / h, the hydrogen feed rate is 92.4 g / h, and the comonomer 1-butene is added at a rate of 11500 g / h (i.e., the ratio of the feed rates of ethylene, hydrogen, and comonomer 1-butene is 1 kg / h: 1.2 g / h: 150 g / h); an ethylene-butene copolymer is obtained. The solvent is separated from the slurry discharged from the second reactor and dried to obtain the final polymer powder.

[0097] (3) This step is consistent with Example 1.

[0098] Example 4

[0099] A method for preparing an ethylene-based resin composition is carried out in a continuous process in two slurry reactors connected in series, and the specific steps are as follows.

[0100] (1) The Z-N catalyst prepared by the above method is continuously fed into the first reactor at a feed rate of 15.1 mmol / h, the cocatalyst (triethylaluminum) is continuously fed into the first reactor at a feed rate of 150 mmol / h, the ethylene feed rate is 75 kg / h, and the hydrogen feed rate is 105 g / h (i.e., the ratio of the feed rates of ethylene and hydrogen is 1 kg / h: 1.4 g / h) to complete the first-stage ethylene homopolymerization reaction to obtain a first ethylene polymer; the polymerization temperature in the first reactor is 75°C, the reaction pressure is 0.25 MPa, and the reaction time is 15 min. The hydrogen added in the feed to the first reactor is used as a molecular weight regulator, and the hexane is used as a solvent, and the feed rate is 150 kg / h (i.e., the ratio of the feed rates of ethylene and organic solvent is 1:2).

[0101] (2) The stream containing the ethylene homopolymer from the first reactor is fed into the second reactor; the polymerization temperature in the second reactor is 65°C, the reaction pressure is 0.45 MPa, and the reaction time is 25 min. In the feed to the second reactor, the ethylene feed rate is 75 kg / h, the hydrogen feed rate is 45 g / h, and the comonomer 1-butene is added at a rate of 7500 g / h (i.e., the ratio of the feed rates of ethylene, hydrogen, and comonomer 1-butene is 1 kg / h: 0.6 g / h: 100 g / h); an ethylene-butene copolymer is obtained. The solvent is separated from the slurry discharged from the second reactor and dried to obtain the final polymer powder.

[0102] (3) This step is consistent with Example 1.

[0103] Example 5

[0104] A method for preparing an ethylene-based resin composition is carried out in a continuous process in two slurry reactors connected in series, and the specific steps are as follows.

[0105] (1) The Z-N catalyst prepared in the above method was continuously fed into the first reactor at a feed rate of 15.1 mmol / h, the co-catalyst (triethylaluminum) was continuously fed into the first reactor at a feed rate of 150 mmol / h, the ethylene feed rate was 75 kg / h, and the hydrogen feed rate was 135 g / h (i.e., the ratio of the ethylene feed rate to the hydrogen feed rate was 1 kg / h: 1.8 g / h) to complete the first-stage ethylene homopolymerization reaction to obtain a first ethylene polymer; the polymerization reaction temperature of the first reactor was 72°C, the reaction pressure was 0.6 MPa, and the reaction time was 35 min. Hydrogen was added to the feed of the first reactor as a molecular weight regulator, and hexane was added to the feed of the first reactor as a solvent at a feed rate of 150 kg / h (i.e., the ratio of the ethylene feed rate to the organic solvent feed rate was 1:2).

[0106] (2) The ethylene homopolymer-containing stream obtained from the first reactor was fed into the second reactor; the polymerization reaction temperature of the second reactor was 73°C, the reaction pressure was 0.5 MPa, and the reaction time was 15 min. In the feed of the second reactor, the ethylene feed rate was 77 kg / h, the hydrogen feed rate was 123.2 g / h, and the comonomer 1-butene was added at a rate of 13860 g / h (i.e., the ratio of the ethylene feed rate to the hydrogen feed rate to the comonomer 1-butene feed rate was 1 kg / h: 1.6 g / h: 180 g / h); an ethylene-butene copolymer was obtained. The solvent was separated from the slurry discharged from the second reactor and dried to obtain the final polymer powder.

[0107] (3) This step is consistent with Example 1.

[0108] Example 6

[0109] A method for preparing an ethylene-based resin composition was performed in a continuous manner in two slurry reactors connected in series, and the specific steps were as follows.

[0110] (1) The Z-N catalyst prepared in the above method was continuously fed into the first reactor at a feed rate of 15.1 mmol / h, the co-catalyst (triethylaluminum) was continuously fed into the first reactor at a feed rate of 150 mmol / h, the ethylene feed rate was 75 kg / h, and the hydrogen feed rate was 530 g / h (i.e., the ratio of the ethylene feed rate to the hydrogen feed rate was 1 kg / h: 7.1 g / h) to complete the first-stage ethylene homopolymerization reaction to obtain a first ethylene polymer; the polymerization reaction temperature of the first reactor was 85°C, the reaction pressure was 0.25 MPa, and the reaction time was 18 min. Hydrogen was added to the feed of the first reactor as a molecular weight regulator, and hexane was added to the feed of the first reactor as a solvent at a feed rate of 150 kg / h (i.e., the ratio of the ethylene feed rate to the organic solvent feed rate was 1:2).

[0111] (2) The stream containing the ethylene homopolymer from the first reactor is fed into the second reactor; the polymerization temperature in the second reactor is 62°C, the reaction pressure is 0.18 MPa, and the reaction time is 35 min. In the feed to the second reactor, the ethylene feed rate is 77 kg / h, the hydrogen feed rate is 154 g / h, and the comonomer 1-butene is added at a rate of 9240 g / h (i.e., the ratio of the feed rates of ethylene, hydrogen, and comonomer 1-butene is 1 kg / h:2 g / h:120 g / h); an ethylene-butene copolymer is obtained. The solvent is separated from the slurry discharged from the second reactor and dried to obtain the final polymer powder.

[0112] (3) This step is consistent with Example 1.

[0113] Example 7

[0114] A method for preparing an ethylene-based resin composition is carried out in a continuous manner in two slurry reactors connected in series, and the specific steps are as follows.

[0115] (1) The Z-N catalyst prepared by the above method is continuously fed into the first reactor at a feed rate of 15.1 mmol / h, the cocatalyst (triethylaluminum) is continuously fed into the first reactor at a feed rate of 150 mmol / h, the ethylene feed rate is 69 kg / h, and the hydrogen feed rate is 414 g / h (i.e., the ratio of the feed rates of ethylene and hydrogen is 1 kg / h:6.0 g / h) to complete the first-stage ethylene homopolymerization to obtain a first ethylene polymer; the polymerization temperature in the first reactor is 84°C, the reaction pressure is 0.4 MPa, and the reaction time is 25 min. The hydrogen added in the feed to the first reactor is used as a molecular weight regulator, and the hexane is used as a solvent, and the feed rate is 150 kg / h (i.e., the ratio of the feed rates of ethylene and organic solvent is 1:2.17).

[0116] (2) The stream containing the ethylene homopolymer from the first reactor is fed into the second reactor; the polymerization temperature in the second reactor is 70°C, the reaction pressure is 0.3 MPa, and the reaction time is 22 min. In the feed to the second reactor, the ethylene feed rate is 77 kg / h, the hydrogen feed rate is 62 g / h, and the comonomer 1-butene is added at a rate of 7700 g / h (i.e., the ratio of the feed rates of ethylene, hydrogen, and comonomer 1-butene is 1 kg / h:0.81 g / h:100 g / h); an ethylene-butene copolymer is obtained. The solvent is separated from the slurry discharged from the second reactor and dried to obtain the final polymer powder.

[0117] (3) This step is consistent with Example 1.

[0118] Example 8

[0119] A method for preparing an ethylene-based resin composition is carried out in a continuous manner in two slurry reactors connected in series, and the specific steps are as follows.

[0120] (1) The Z-N catalyst prepared in the above method was continuously fed into the first reactor at a feed rate of 15.1 mmol / h, the cocatalyst (triethylaluminum) was continuously fed into the first reactor at a feed rate of 150 mmol / h, the ethylene feed rate was 69 kg / h, and the hydrogen feed rate was 276 g / h (i.e., the ratio of the ethylene feed rate to the hydrogen feed rate was 1 kg / h:4.0 g / h) to complete the first-stage ethylene homopolymerization reaction to obtain a first ethylene polymer; the polymerization temperature in the first reactor was 78°C, the reaction pressure was 0.5 MPa, and the reaction time was 20 min. Hydrogen was added to the feed of the first reactor as a molecular weight regulator, and hexane was added to the feed of the first reactor as a solvent at a feed rate of 150 kg / h (i.e., the ratio of the ethylene feed rate to the organic solvent feed rate was 1:2.17).

[0121] (2) The ethylene homopolymer-containing stream obtained from the first reactor was fed into the second reactor; the polymerization temperature in the second reactor was 72°C, the reaction pressure was 0.2 MPa, and the reaction time was 20 min. In the feed of the second reactor, the ethylene feed rate was 77 kg / h, the hydrogen feed rate was 77 g / h, and the comonomer 1-butene was added at a rate of 15400 g / h (i.e., the ratio of the ethylene feed rate to the hydrogen feed rate to the comonomer 1-butene feed rate was 1 kg / h:1 g / h:200 g / h); an ethylene-butene copolymer was obtained. The solvent was separated from the slurry discharged from the second reactor and dried to obtain the final polymer powder.

[0122] (3) This step was consistent with Example 1.

[0123] Comparative Example 1

[0124] A method for preparing an ethylene-based resin composition:

[0125] This comparative example differed from Example 1 only in that in step (1), the ratio of the ethylene feed rate to the hydrogen feed rate was changed to 1 kg / h:0.5 g / h.

[0126] Comparative Example 2

[0127] A method for preparing an ethylene-based resin composition:

[0128] This comparative example differed from Example 1 only in that:

[0129] in step (1), the ratio of the ethylene feed rate to the hydrogen feed rate was changed to 1 kg / h:1 g / h; and in step (2), the ratio of the ethylene feed rate to the hydrogen feed rate to the comonomer 1-butene feed rate was changed to 1 kg / h:5 g / h:20 g / h.

[0130] Comparative Example 3

[0131] A method for preparing an ethylene-based resin composition:

[0132] This comparative example differs from Example 1 only in that, in step (1), the polymerization reaction temperature of the first reactor is changed to 68°C, the reaction pressure is changed to 1.0 MPa, and the reaction time is changed to 120 min.

[0133] Comparative Example 4

[0134] A method for producing an ethylene-based resin composition:

[0135] This comparative example differs from Example 1 only in that, in step (1), the polymerization reaction temperature of the first reactor is changed to 88°C, the reaction pressure is changed to 0.05 MPa, and the reaction time is changed to 5 min.

[0136] Comparative Example 5

[0137] A method for producing an ethylene-based resin composition:

[0138] This comparative example differs from Example 1 only in that:

[0139] in step (1), the ratio of the feed amounts of ethylene and hydrogen is changed to 1 kg / h: 8 g / h; and, in step (2), the ratio of the feed amounts of ethylene, hydrogen, and comonomer 1-butene is changed to 1 kg / h: 0.4 g / h: 220 g / h.

[0140] Comparative Example 6

[0141] A method for producing an ethylene-based resin composition:

[0142] This comparative example differs from Example 1 only in that:

[0143] in step (1), the ratio of the feed amounts of ethylene and hydrogen is changed to 1 kg / h: 8 g / h; and, in step (2), the ratio of the feed amounts of ethylene, hydrogen, and comonomer 1-butene is changed to 1 kg / h: 3.0 g / h: 80 g / h.

[0144] Comparative Example 7

[0145] This comparative example differs from Example 1 only in that, in step (2), the polymerization reaction temperature of the second reactor is changed to 55°C, the reaction pressure is changed to 0.7 MPa, and the reaction time is changed to 120 min.

[0146] Comparative Example 8

[0147] This comparative example differs from Example 1 only in that, in step (2), the polymerization reaction temperature of the second reactor is changed to 80°C, the reaction pressure is changed to 0.05 MPa, and the reaction time is changed to 5 min.

[0148] Test method

[0149] Short chain branching (SCB) information: obtained by high temperature gel permeation chromatography (GPC-IR5) test equipped with IR5 infrared detector.

[0150] Long chain branching (LCB) information: obtained by high temperature gel permeation chromatography (GPC-IR5-LS) test equipped with light scattering detector.

[0151] Molecular weight and distribution: high temperature gel permeation chromatography (GPC) of GPC-IR type of PolymerChar company (Spain) equipped with internal IR5 infrared detector and light scattering detector, the automatic injector heating zone is set to 160°C, the column temperature is set to 150°C, the sample is dissolved with 1,2,4-trichlorobenzene, the concentration is 1.0 mg / ml, the injection volume is 200 μl, and the solution flow rate is 1.0 ml / min.

[0152] The molecular weight of polystyrene is used as an internal reference to prepare a standard curve, and the molecular weight and distribution of the sample are calculated according to the elution time, and the number average molecular weight (M n ), weight average molecular weight (M w ), Z average molecular weight (M z ), Z+1 average molecular weight (M z+1 ) and other parameters are calculated.

[0153] Melt mass flow rate (MFR): tested according to GB / T 3682-2018.

[0154] Density: tested according to GB / T 1033.2-2010.

[0155] Notched impact strength: determined according to the method specified in GB / T 1043.1-2008.

[0156] Tensile properties: determined according to the method specified in GB / T 1040.2-2006.

[0157] Environmental stress cracking resistance (ESCR): tested according to GB / T 1842-2008, using condition B.

[0158] Full notched creep test (FNCT): full notched creep test is carried out according to ISO 16770 at a stress of 4.0 MPa and a temperature of 80°C. Specifically, the sample size for FNCT is a cuboid of 10x10x100 mm, which is obtained by grinding a plate with a thickness of 15 mm. Then, a notch with a depth of 1.5 mm is formed on four sides of the sample, a stress of 4.0 MPa is applied to the sample in a 10% Igepal solution at 80°C, and then the time taken for the sample to break is measured.

[0159] Flexural Creep Test: A three-point flexural creep test was performed at 23°C using an injection-molded test specimen having a length of 127 mm, a width of 12.7 mm, and a thickness of 3 mm. The distance between the fulcrums was set to 48 mm, and the deformation of the test specimen after 1000 hours was measured after a load of 5.0 MPa was applied to the center thereof.

[0160] Tensile Rheology Test: A rotational rheometer equipped with a SER tensile rheology fixture was used to measure the tensile viscosity during uniaxial extension as a function of time at a constant tensile rate of 0.1 s -1

[0161] Helical Flow Length: Helical flow length measurements were performed by molding a polymer sample into a helical flow die having a thickness of 0.127 centimeters on an injection molding machine at a melt temperature of 250°C and a mold temperature of 25°C under an injection pressure of 137.9 MPa. The flow length (in centimeters) of the polymer into the die was measured.

[0162] The test results described above are shown in Tables 1 and 2. Also, the content of the ethylene homopolymer, the melt mass flow rate, and the density of each of the resulting resin compositions are shown in Table 3.

[0163] Table 1

[0164]

[0165]

[0166] Table 2

[0167]

[0168]

[0169] Table 3

[0170]

[0171] From the above description, it can be seen that, compared with the respective comparative examples, the above-described embodiments of the present application, especially Examples 3, 7, and 8, by finely adjusting the condition parameters in the two-step polymerization process, thereby strictly controlling the specific structural composition in the ethylene-based resin composition, and accurately controlling the short chain branching distribution factor SCBI and LCBF of the resin composition, an ethylene-based resin composition having good flowability, dimensional stability, stress cracking resistance, and processing performance was prepared. Each of the resulting resin compositions exhibited excellent performance in tensile yield stress, tensile nominal strain at break, Charpy notched impact strength, ESCR, FNCT, flexural creep, tensile strain hardening, and the like.​

[0172] It should be noted that the terms "first", "second", and the like in the description and in the claims of this application are used for distinguishing between similar objects and not necessarily for describing a particular sequential or chronological order. It is to be understood that the terms so used are interchangeable under appropriate circumstances such that the embodiments of the application described herein are, for example, capable of practical implementation irrespective of the particular sequential or chronological order of the steps contained therein.

[0173] The preferred embodiments of the application are described above in detail for the purposes of clarity and understanding. It should be appreciated that the application can be practiced in a variety of ways in accordance with the description provided herein, including modifications and / or alterations without departing from the spirit and scope of the application. Accordingly, the drawings and description are to be regarded as illustrative in nature and not restrictive.

Claims

1. A vinyl resin composition, characterized by, The vinyl resin composition includes an ethylene homopolymer and an ethylene-butene copolymer, and the weight ratio of the ethylene homopolymer to the ethylene-butene copolymer is 1:(0.6-1.5); The short chain branching index SCBI of the vinyl resin composition is 0.02-0.04; The long chain branching index LCBF of the vinyl resin composition is 0.05-0.

85.

2. The vinyl resin composition according to claim 1, wherein the weight ratio of the ethylene homopolymer to the ethylene-butene copolymer is 1:(0.7-1.35); and / or the short chain branching index SCBI of the vinyl resin composition is 0.024-0.035; and / or the long chain branching index LCBF of the vinyl resin composition is 0.08-0.

80.

3. The vinyl resin composition according to claim 1 or 2, wherein the vinyl resin composition has a melt mass flow rate of 0.5-2.5 g / 10 min, preferably 1.0-2.2 g / 10 min, at 190°C under a load of 2.16 kg.

4. The vinyl resin composition according to any one of claims 1-3, wherein the vinyl resin composition has a tensile yield stress of 15-30 MPa, preferably 18-25 MPa; and / or a tensile strain at break of 400-550%, preferably 450-550%.

5. The vinyl resin composition according to any one of claims 1-4, wherein the vinyl resin composition has a tensile yield stress of 15-30 MPa, preferably 18-25 MPa; and / or a tensile strain at break of 400-550%, preferably 450-550%. The weight average molecular weight M of the ethylene-based resin composition w With the number average molecular weight M n Satisfies: 10 ≤ M w / M n ≤ 20, preferably 12 ≤ M w / M n ≤ 20; and / or, Z-average molecular weight M z Z+1 average molecular weight M z+1 satisfies: 2.0 ≤ M z+1 / M z ≤ 3.0, preferably 2.1 ≤ M z+1 / M z ≤ 3.0; and / or, The Z-average molecular weight M z with the weight average molecular weight M w satisfies: 4.0 ≤ M z / M w ≤ 5.5, preferably 4.5 ≤ M z / M w ≤ 5.

5.

6. The vinyl resin composition according to any one of claims 1-5, wherein the vinyl resin composition has a tensile strain hardening value of 2.0-4.0, preferably 3.0-4.

0.

7. The vinyl resin composition according to any one of claims 1-6, wherein the vinyl resin composition has an environmental stress cracking resistance time of 400-750 h, preferably 600-750 h; and / or a tensile yield stress of 15-30 MPa, preferably 18-25 MPa; and / or a tensile strain at break of 400-550%, preferably 450-550%.

8. The vinyl resin composition according to any one of claims 1-7, wherein the vinyl resin composition has a tensile strain hardening value of 2.0-4.0, preferably 3.0-4.

0.

9. The vinyl resin composition according to any one of claims 1-8, wherein the vinyl resin composition has an environmental stress cracking resistance time of 400-750 h, preferably 600-750 h; and / or a tensile yield stress of 15-30 MPa, preferably 18-25 MPa; and / or a tensile strain at break of 400-550%, preferably 450-550%. The density of the ethylene-based resin composition is 0.948 g / cm 3 ~ 0.957 g / cm 3 , preferably 0.950 g / cm 3 ~ 0.955 g / cm 3 ; and / or, 10. The vinyl resin composition according to any one of claims 1-9, wherein the vinyl resin composition has a tensile strain hardening value of 2.0-4.0, preferably 3.0-4.

0.

6. The ethylene-based resin composition according to any one of claims 1 to 5, characterized in that, the density of the ethylene homopolymer in the ethylene-based resin composition is 0.955 g / cm3 3 ~ 0.960 g / cm3 3 , preferably 0.956 g / cm3 3 ~ 0.959 g / cm3 3 ; and / or, the melt mass flow rate of the ethylene homopolymer in the ethylene-based resin composition is 10 g / 10 min ~ 50 g / 10 min, preferably 15 g / 10 min ~ 45 g / 10 min, at 190 °C, under a load of 2.16 kg.

7. The ethylene-based resin composition according to any one of claims 1 to 6, characterized in that, The notched impact strength of the ethylene-based resin composition is 15 kJ / m 2 ~ 25 kJ / m 2 , preferably 18 kJ / m 2 ~ 25 kJ / m 2 . ​ ​ ​ ​ ​ ​ ​ ​ The vinyl resin composition is subjected to a flexural creep test at 23°C and 5.0 MPa for 1000 hours, and the deformation amount is 0.7% to 1.0%, preferably 0.7% to 0.8%.

11. The ethylene-based resin composition of any one of claims 1 to 10, characterized in that, The spiral flow length of the vinyl resin composition is 70 cm to 80 cm, preferably 75 cm to 80 cm, at 137.9 MPa.

12. A method for producing the ethylene-based resin composition according to any one of claims 1 to 11, characterized by, Comprising: Step S1, ethylene and hydrogen are subjected to a first polymerization reaction to obtain the ethylene homopolymer; the ratio of the feeding amount of ethylene to the feeding amount of hydrogen is 1 kg / h:(1.0 g / h to 8.0 g / h); Step S2, the ethylene homopolymer, ethylene, hydrogen and 1-butene are subjected to a second polymerization reaction to form the ethylene-butene copolymer in the ethylene homopolymer, thereby obtaining the vinyl resin composition; the ratio of the feeding amount of ethylene to the feeding amount of hydrogen to the feeding amount of 1-butene is 1 kg / h:(0.5 g / h to 2.5 g / h):(100 g / h to 200 g / h).

13. The method of producing a vinyl resin composition according to claim 12, characterized by, The reaction temperature of the first polymerization reaction is 70°C to 86°C, the reaction pressure is 0.1 MPa to 0.8 MPa, and the reaction time is 10 min to 100 min; and / or, the reaction temperature of the second polymerization reaction is 60°C to 75°C, the reaction pressure is 0.1 to 0.6 MPa, and the reaction time is 10 min to 100 min.

14. The method of producing a vinyl resin composition according to claim 12 or 13, characterized by, The reaction temperature of the first polymerization reaction is 72°C to 85°C, the reaction pressure is 0.2 MPa to 0.6 MPa, and the reaction time is 15 min to 40 min; and / or, the reaction temperature of the second polymerization reaction is 62°C to 73°C, the reaction pressure is 0.15 MPa to 0.50 MPa, and the reaction time is 15 min to 25 min.

15. The method of producing a vinyl resin composition according to any one of claims 12 to 14, characterized in that, In the step S1, the organic solvent used in the first polymerization reaction is selected from one or more of C3 to C10 hydrocarbon solvents; Preferably, the organic solvent is selected from one or more of pentane, hexane, heptane and octane, more preferably hexane; Further preferably, in the step S1, the ratio of the feeding amount of ethylene to the feeding amount of the organic solvent is 1: (1.8～2.4)。 16. Use of the vinyl resin composition according to any one of claims 1 to 11 as an injection molding plastic or compression molding plastic to produce a plastic product.

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