In-situ nucleated isotactic polybutene-1 and preparation method thereof

Abstract

The present application provides an in-situ nucleated isotactic polybutene-1 and a preparation method thereof. The preparation method provided by the present invention comprises: a) reacting a main catalyst, a co-catalyst, a polymer nucleating agent monomer and a solvent, and then removing the solvent to obtain material A; b) mixing the material A with a co-catalyst and an external electron donor, adding a liquid phase butene-1 monomer and passing hydrogen, and performing butene-1 bulk prepolymerization under low temperature conditions; the low temperature condition is ≤10°C; c) heating up for bulk polymerization to obtain in-situ nucleated isotactic polybutene-1; wherein: the main catalyst is a Ziegler-Natta catalyst; the co-catalyst is an alkyl aluminum compound; the polymer nucleating agent monomer is a vinyl compound; and the external electron donor is a silane compound. The preparation method provided by the present invention realizes isotactic polybutene-1 with excellent crystallization performance at a relatively low nucleating agent concentration.

Description

Technical Field

[0001] The invention relates to the field of polymer materials, and in particular to an in-situ nucleated isotactic polybutene-1 and a preparation method thereof. Background Art

[0002] Isotactic polybutene-1 is a linear polyolefin material synthesized with butene-1 as a monomer. It has outstanding heat resistance, creep resistance, good toughness, wear resistance and excellent processability. It can be used to make floor heating pipes, easy-to-peel films and plates, etc. It has broad application prospects and is also known as "plastic gold".

[0003] However, isotactic polybutene-1 has a variety of crystal structures. Under normal conditions, type II crystals are obtained by melt extrusion cooling crystallization. Type II crystals are thermodynamically unstable and can spontaneously transform into the more stable type I crystal at room temperature. The crystal transformation cycle is as long as 7 days, which prolongs the storage period of the product after molding and increases the production cost. In addition, the isotactic polybutene-1 material produced by traditional preparation technology does not contain a nucleating agent component. The obtained polybutene-1 has a low degree of crystallinity and has crystal defects, which affects the physical and mechanical properties of the material, especially the poor dimensional stability of the product, which seriously affects the application of polybutene-1.

[0004] At present, in industrial production, the method of adding a nucleating agent during the processing of polybutene-1 is mainly used to accelerate the crystal transformation process of isotactic polybutene-1 and improve its crystal defects. Commonly used polybutene-1 nucleating agents such as dibasic acid diamides (CN 106147044 B), dibasic acid dihydrazides (CN 105924811 B), dibasic acid metal salts (CN106147045), graphene (CN 103627094 B), talcum powder (CN 105670137), etc., the concentration of the nucleating agent added is relatively high, usually 500-2000ppm, such a high concentration of addition will not only affect the physical and mechanical properties of isotactic polybutene-1 but also produce a relatively unpleasant odor during the processing, causing environmental pollution, and the nucleating agent cannot be evenly dispersed in the isotactic polybutene-1 matrix, affecting the product quality stability. In addition, the addition of high concentration of nucleating agent significantly increases the processing cost of isotactic polybutene-1.

[0005] The in-situ nucleation technology for polyolefins is a technology that directly forms polymer nucleating agents during the synthesis of polyolefins. This technology can replace the traditional nucleating technology of adding nucleating agents during the subsequent processing of polyolefins. Since the nucleating agents in the in-situ nucleation technology exist in the polymerization system before the polymer is formed, their dispersion effect is better, and the same effect as expensive high-performance nucleating agents can be achieved at a lower cost. At the same time, the processing performance and mechanical properties are improved compared with traditional nucleating technologies, especially the basic performance of product dimensional stability is improved.

[0006] However, in theory, the in-situ nucleation technology of polyolefins has certain advantages over the nucleation technology of adding nucleating agents during the subsequent processing of polyolefins. However, in actual production, how to truly achieve better results still faces certain challenges. Summary of the invention

[0007] In view of this, the object of the present invention is to provide an in-situ nucleated isotactic polybutene-1 and a preparation method thereof. The preparation method provided by the present invention can smoothly prepare in-situ nucleated isotactic polybutene-1 under the condition of low concentration of polymer nucleating agent, and the obtained isotactic polybutene-1 has high crystallinity, high crystallization temperature, and short crystal transformation period, so as to achieve isotactic polybutene-1 with excellent crystallization performance at a lower nucleating agent concentration.

[0008] The present invention provides a method for preparing in-situ nucleated isotactic polybutene-1, comprising the following steps:

[0009] a) mixing a main catalyst, a co-catalyst, a polymer nucleating agent monomer and a solvent for reaction, and then removing the solvent to obtain material A;

[0010] b) mixing the material A with a co-catalyst and an external electron donor, adding liquid phase butene-1 monomer and introducing hydrogen, and performing butene-1 bulk prepolymerization under low temperature conditions;

[0011] The low temperature condition is ≤10°C;

[0012] c) heating to carry out bulk polymerization to obtain in-situ nucleated isotactic polybutene-1;

[0013] in:

[0014] The main catalyst is a Ziegler-Natta catalyst;

[0015] The co-catalyst is an alkyl aluminum compound;

[0016] The polymer nucleating agent monomer is a vinyl compound;

[0017] The external electron donor is a silane compound.

[0018] Preferably, the polymer nucleating agent monomer is selected from at least one of vinyl cyclohexane, vinyl cyclopentane, vinyl-2-methylcyclohexane, 3-methyl-1-butene, 3-ethyl-1-hexene, 3-methyl-1-pentene and styrene.

[0019] Preferably, in step a), the co-catalyst is selected from at least one of triethylaluminum, triisobutylaluminum, trihexylaluminum, trioctylaluminum, diethylaluminum monochloride, diisobutylaluminum monochloride, dihexylaluminum monochloride and dioctylaluminum monochloride;

[0020] In the step b), the co-catalyst is selected from at least one of triethylaluminum, triisobutylaluminum, trihexylaluminum, trioctylaluminum, diethylaluminum monochloride, diisobutylaluminum monochloride, dihexylaluminum monochloride and dioctylaluminum monochloride.

[0021] Preferably, the external electron donor is selected from vinyl triethoxysilane, vinyl trimethoxysilane, methyl triethoxysilane, dimethyl dimethoxysilane, diethyl dimethoxysilane, dipropyl dimethoxysilane, diisopropyl dimethoxysilane, dibutyl dimethoxysilane, diisobutyl dimethoxysilane, di-tert-butyl dimethoxysilane, di-tert-hexyl dimethoxysilane, diphenyl dimethoxysilane, dicyclohexyl dimethoxysilane, dicyclopentyl dimethoxysilane, dimethyl diethoxysilane, diethyl diethoxysilane, dipropyl diethoxysilane, diisopropyl dieth ... At least one of alkyl, diisopropyldiethoxysilane, dibutyldiethoxysilane, diisobutyldiethoxysilane, di-tert-butyldiethoxysilane, di-tert-hexyldiethoxysilane, diphenyldiethoxysilane, dicyclohexyldiethoxysilane, dicyclopentyldiethoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, cyclopentylmethyldimethoxysilane, cyclopentyltrimethoxysilane, cyclohexylmethyldimethoxysilane, cyclohexyltrimethoxysilane, tert-hexyltrimethoxysilane, tert-butyltrimethoxysilane and tert-hexyltrimethoxysilane.

[0022] Preferably, the Ziegler-Natta catalyst is a spherical catalyst of titanium tetrachloride supported on magnesium chloride;

[0023] The solvent is an alkane solvent.

[0024] Preferably, in step a):

[0025] The molar ratio of the co-catalyst to the titanium in the main catalyst is (1-100):1;

[0026] The mass ratio of the polymer nucleating agent monomer to the main catalyst is (0.2-5):1;

[0027] The main catalyst: solvent usage ratio is (1-100) mg: 1 mL;

[0028] The reaction temperature is 0-50°C and the reaction time is 5-20h.

[0029] Preferably, in step b):

[0030] The molar ratio of the co-catalyst to the titanium in the main catalyst of step a) is (50-500):1;

[0031] The molar ratio of the external electron donor to the titanium in the main catalyst of step a) is (5-30):1.

[0032] Preferably, the molar ratio of titanium in the main catalyst to liquid phase butene-1 monomer is (1×10 -7 ~1×10 -5 )∶1;

[0033] In the step b), the partial pressure of hydrogen is 0.5 to 5 bar;

[0034] In the step b), the prepolymerization temperature is -30°C to 10°C, and the time is 0.5 to 3 hours.

[0035] Preferably, in step c), the bulk polymerization temperature is 10 to 60° C. and the time is 2 to 20 hours;

[0036] The co-catalyst is added in the form of a co-catalyst solution; the concentration of the co-catalyst solution is 0.5 to 8 mol / L;

[0037] The external electron donor is added in the form of an external electron donor solution; the concentration of the external electron donor solution is 0.1-5 mol / L.

[0038] The present invention also provides an in-situ nucleated isotactic polybutene-1, which is prepared by the preparation method described in the above technical scheme.

[0039] The preparation method provided by the present invention comprises the following steps: firstly, a main catalyst, a co-catalyst, a polymer nucleating agent monomer and a solvent are mixed and reacted to form a polymer nucleating agent in the system; then, a co-catalyst and an external electron donor are introduced, a liquid phase butene-1 monomer is added and hydrogen is introduced, and low-temperature bulk prepolymerization and room-temperature polymerization of butene-1 are directly performed to finally prepare in-situ nucleated polybutene-1 containing a low-concentration polymer nucleating agent, and the crystallization temperature and crystallinity of the in-situ nucleated polybutene-1 are improved and the crystal form transformation period is shortened, thereby realizing the low-cost preparation of isotactic polybutene-1 with excellent crystallization performance at a relatively low nucleating agent concentration.

[0040] The experimental results show that the content of the polymer nucleating agent in the in-situ nucleated polybutene-1 prepared by the present invention reaches below 500ppm, and the concentration of the nucleating agent is kept low, and the obtained isotactic polybutene-1 can have a higher crystallinity, crystallization temperature and a shorter crystal transformation period. Specifically, the product crystallization temperature reaches above 83°C, the crystallinity reaches above 48.5%, and the crystal transformation period is shortened to below 145h. Further, under preferred conditions, the concentration of the nucleating agent can be further reduced, specifically to below 250ppm (75-250ppm), and the crystallinity, crystallization temperature and crystal transformation period of the isotactic polybutene-1 product can be further improved, specifically, the product crystallization temperature is increased to above 87°C, the crystallinity is increased to above 52%, and the crystal transformation period is shortened to below 70h. DETAILED DESCRIPTION

[0041] The present invention provides a method for preparing in-situ nucleated isotactic polybutene-1, comprising the following steps:

[0042] a) mixing a main catalyst, a co-catalyst, a polymer nucleating agent monomer and a solvent for reaction, and then removing the solvent to obtain material A;

[0043] b) mixing the material A with a co-catalyst and an external electron donor, adding liquid phase butene-1 monomer and introducing hydrogen, and performing butene-1 bulk prepolymerization under low temperature conditions;

[0044] The low temperature condition is ≤10°C;

[0045] c) heating to carry out bulk polymerization to obtain in-situ nucleated isotactic polybutene-1;

[0046] in:

[0047] The main catalyst is a Ziegler-Natta catalyst;

[0048] The co-catalyst is an alkyl aluminum compound;

[0049] The polymer nucleating agent monomer is a vinyl compound;

[0050] The external electron donor is a silane compound.

[0051] The preparation method provided by the present invention comprises the following steps: firstly, a main catalyst, a co-catalyst, a polymer nucleating agent monomer and a solvent are mixed and reacted to form a polymer nucleating agent in the system; then, a co-catalyst and an external electron donor are introduced, a liquid phase butene-1 monomer is added and hydrogen is introduced, and low-temperature bulk prepolymerization and room-temperature polymerization of butene-1 are directly performed to finally prepare in-situ nucleated polybutene-1 containing a low-concentration polymer nucleating agent, and the crystallization temperature and crystallinity of the in-situ nucleated polybutene-1 are improved and the crystal transformation period is shortened, so that the isotactic polybutene-1 presents excellent crystallization performance at a relatively low nucleating agent concentration, which is of great significance in industry and commerce.

[0052] [About step a]:

[0053] a) mixing a main catalyst, a co-catalyst, a polymer nucleating agent monomer and a solvent for reaction, and then removing the solvent to obtain material A.

[0054] In the present invention, the steps a) to c) are preferably carried out under a protective atmosphere. Specifically, before feeding, gas replacement is performed with the reaction device in advance to form a protective atmosphere in the reaction device, and then the feeding and reaction of steps a) to c) are carried out. The present invention has no particular limitation on the type of gas forming the protective atmosphere, and it can be a conventional inert gas in the art, such as nitrogen, helium or argon.

[0055] In the present invention, the main catalyst is a Ziegler-Natta catalyst, specifically a magnesium chloride-supported titanium tetrachloride spherical catalyst. The present invention has no special restrictions on the source of the main catalyst, and it can be a commercial product. For example, in some embodiments of the present invention, a CS series catalyst of Liaoning Xiangyang Science and Technology Chemical Group Catalyst Company is used, and the titanium content is 2.3wt%.

[0056] In the present invention, the co-catalyst is an alkyl aluminum compound; preferably at least one of triethyl aluminum, triisobutyl aluminum, trihexylaluminum, trioctylaluminum, diethylaluminum monochloride, diisobutylaluminum monochloride, dihexylaluminum monochloride and dioctylaluminum monochloride; more preferably one or two of the above alkyl aluminum compounds.

[0057] In the present invention, the co-catalyst is preferably added in the form of a co-catalyst solution, that is, the co-catalyst is preliminarily dissolved in a solvent to prepare a co-catalyst solution, and then the co-catalyst solution is added to the reaction system. The solvent used to prepare the solution is preferably at least one of n-hexane, n-heptane and n-octane. The concentration of the co-catalyst solution is preferably 0.5 to 8 mol / L, more preferably 1 mol / L.

[0058] In the present invention, the polymer nucleating agent monomer is a monomer used to form a polymer nucleating agent, which is a vinyl compound; preferably at least one of vinyl cyclohexane, vinyl cyclopentane, vinyl-2-methylcyclohexane, 3-methyl-1-butene, 3-ethyl-1-hexene, 3-methyl-1-pentene and styrene.

[0059] In the present invention, the solvent is preferably an alkane solvent, more preferably at least one of n-pentane, isopentane, n-hexane, n-heptane and n-octane.

[0060] In the present invention, in step a), the dosage relationship between the materials is preferably as follows:

[0061] The molar ratio of titanium in the co-catalyst:main catalyst is preferably (1-100):1, specifically 1:1, 10:1, 20:1, 30:1, 40:1, 50:1, 60:1, 70:1, 80:1, 90:1, 100:1.

[0062] The mass ratio of the polymer nucleating agent monomer to the main catalyst is preferably (0.2-5):1, specifically 0.2:1, 0.5:1, 1.0:1, 1.5:1, 2.0:1, 2.5:1, 3.0:1, 3.5:1, 4.0:1, 4.5:1, 5.0:1; within the above ratio range, the content of the polymer nucleating agent in the isotactic polybutene-1 can reach below 500 ppm, maintaining a low nucleating agent concentration, and at the same time, the obtained isotactic polybutene-1 can have a higher crystallinity, crystallization temperature and a shorter crystal transformation period. Specifically, the product crystallization temperature reaches above 83°C, the crystallinity reaches above 48.5%, and the crystal transformation period is shortened to below 145h. In the present invention, the mass ratio is more preferably (0.5-5): 1. At this preferred ratio, the crystallinity and crystallization temperature of the isotactic polybutene-1 product can be further improved and the crystal transformation period can be shortened. Specifically, the crystallization temperature of the product is increased to above 87°C, the crystallinity is increased to above 52%, and the crystal transformation period is shortened to below 70h. In the present invention, the mass ratio is most preferably (0.5-1.5): 1. At this preferred ratio, the concentration of the nucleating agent can be further reduced, specifically to below 250ppm (75-250ppm), and the obtained isotactic polybutene-1 is ensured to have a higher crystallinity, crystallization temperature and a shorter crystal transformation period.

[0063] The usage ratio of the main catalyst:solvent is preferably (1-100) mg:1 mL.

[0064] In the present invention, the four materials of main catalyst, co-catalyst, polymer nucleating agent monomer and solvent are mixed and reacted. The above reaction is a polymerization reaction. During the reaction, the co-catalyst reduces the titanium tetrachloride loaded on the surface of the spherical main catalyst to low-valent titanium such as titanium trichloride or titanium dichloride. The low-valent titanium acts as an active center to initiate the polymerization reaction of the polymer nucleating agent monomer on the spherical surface of the main catalyst to generate a polymer nucleating agent, which is evenly distributed on the surface of the spherical main catalyst. In the present invention, the temperature of the reaction is preferably 0 to 50°C, specifically 0°C, 5°C, 10°C, 15°C, 20°C, 25°C, 30°C, 35°C, 40°C, 45°C, 50°C. The reaction time is preferably 5 to 20h, specifically 5h, 10h, 15h, 20h. After the above reaction, a reaction solution is obtained.

[0065] In the present invention, after the above reaction, the solvent is removed from the obtained reaction solution. In the present invention, the method of removing the solvent is preferably: using a diaphragm vacuum pump to evacuate the reaction system to remove the solvent. The temperature condition of the above operation is preferably 30 to 60° C. After the solvent is removed, material A is obtained.

[0066] [About step b]:

[0067] b) mixing the material A with a co-catalyst and an external electron donor, adding liquid butene-1 monomer and introducing hydrogen, and performing butene-1 bulk prepolymerization at low temperature.

[0068] In the present invention, the cocatalyst is an alkyl aluminum compound; preferably at least one of triethyl aluminum, triisobutyl aluminum, trihexyl aluminum, trioctylaluminum, diethyl aluminum monochloride, diisobutyl aluminum monochloride, dihexyl aluminum monochloride and dioctyl aluminum monochloride; more preferably one or two of the above alkyl aluminum compounds. The cocatalyst may be the same or different from the cocatalyst used in step a), preferably the same.

[0069] In the present invention, the co-catalyst is preferably added in the form of a co-catalyst solution, that is, the co-catalyst is preliminarily dissolved in a solvent to prepare a co-catalyst solution, and then the co-catalyst solution is added to the reaction system. The solvent used to prepare the solution is preferably at least one of n-hexane, n-heptane and n-octane. The concentration of the co-catalyst solution is preferably 0.5 to 8 mol / L, more preferably 1 mol / L.

[0070] In the present invention, the molar ratio of the co-catalyst to the titanium in the main catalyst of step a) is preferably (50-500):1, specifically 50:1, 100:1, 150:1, 200:1, 250:1, 300:1, 350:1, 400:1, 450:1, 500:1.

[0071] In the present invention, the external electron donor is a silane compound, preferably vinyl triethoxysilane, vinyl trimethoxysilane, methyl triethoxysilane, dimethyl dimethoxysilane, diethyl dimethoxysilane, dipropyl dimethoxysilane, diisopropyl dimethoxysilane, dibutyl dimethoxysilane, diisobutyl dimethoxysilane, di-tert-butyl dimethoxysilane, di-tert-hexyl dimethoxysilane, diphenyl dimethoxysilane, dicyclohexyl dimethoxysilane, dicyclopentyl dimethoxysilane, dimethyl diethoxysilane, diethyl diethoxysilane, dipropyl diethoxysilane, diisopropyl At least one of dimethoxysilane, dibutyldiethoxysilane, diisobutyldiethoxysilane, di-tert-butyldiethoxysilane, di-tert-hexyldiethoxysilane, diphenyldiethoxysilane, dicyclohexyldiethoxysilane, dicyclopentyldiethoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, cyclopentylmethyldimethoxysilane, cyclopentyltrimethoxysilane, cyclohexylmethyldimethoxysilane, cyclohexyltrimethoxysilane, tert-hexyltrimethoxysilane, tert-butyltrimethoxysilane and tert-hexyltrimethoxysilane; more preferably one or two of the above silane compounds.

[0072] In the present invention, the external electron donor is preferably added in the form of an external electron donor solution, that is, the external electron donor is dissolved in a solvent in advance to prepare an external electron donor solution, and then the external electron donor solution is added to the reaction system. The solvent used to prepare the solution is preferably at least one of n-pentane, isopentane, n-hexane and n-hexane. The concentration of the external electron donor solution is preferably 0.1 to 5 mol / L, more preferably 0.2 mol / L.

[0073] In the present invention, the molar ratio of the external electron donor to the titanium in the main catalyst of step a) is preferably (5-30):1, specifically 5:1, 10:1, 15:1, 20:1, 25:1, 30:1.

[0074] In the present invention, in addition to the above materials, liquid phase butene-1 monomer is added to the system. In the present invention, the molar ratio of titanium in the main catalyst to liquid phase butene-1 monomer in step a) is preferably (1×10 -7 ~1×10 -5 )∶1, specifically 1×10 -7 ∶1、1×10 -6 ∶1、1×10 -5 ∶1.

[0075] In the present invention, hydrogen is also introduced into the system. In the present invention, the partial pressure of the hydrogen is preferably 0.5 to 5 bar, specifically 0.5 bar, 1 bar, 1.5 bar, 2 bar, 2.5 bar, 3 bar, 3.5 bar, 4 bar, 4.5 bar, 5 bar.

[0076] In the present invention, the mixing of the above materials is preferably carried out under low temperature conditions, that is, the system is cooled to low temperature conditions in advance, and then the materials are added. The low temperature conditions refer to a temperature ≤ 10°C, more preferably -30°C to 10°C, specifically -30°C, -25°C, -20°C, -15°C, -10°C, -5°C, 0°C, 5°C, 10°C.

[0077] In the present invention, after all the above materials are added, the butene-1 bulk prepolymerization is carried out under low temperature conditions. In the present invention, the low temperature conditions refer to a temperature ≤ 10°C, more preferably -30°C to 10°C, specifically -30°C, -25°C, -20°C, -15°C, -10°C, -5°C, 0°C, 5°C, 10°C. The time for controlling the prepolymerization under the above low temperature conditions is preferably 0.5 to 3h, specifically 0.5h, 1h, 1.5h, 2h, 2.5h, 3h. After the above bulk prepolymerization, a prepolymer is obtained.

[0078] [About step c]:

[0079] c) heating to carry out bulk polymerization to obtain in-situ nucleated isotactic polybutene-1.

[0080] In the present invention, after the prepolymerization in step b) is completed, the temperature is continued to be raised for bulk polymerization. In the present invention, the temperature of the bulk polymerization is preferably 10 to 60°C, specifically 10°C, 15°C, 20°C, 25°C, 30°C, 35°C, 40°C, 45°C, 50°C, 55°C, 60°C. In the present invention, step c) is to further heat up for bulk polymerization, that is, the temperature of bulk polymerization is greater than the temperature of bulk prepolymerization in step b), which implies that the temperature of bulk polymerization in step c) is different from the temperature of bulk prepolymerization in step b) at 10°C. In the present invention, the time of the bulk polymerization is preferably 2 to 20h, specifically 2h, 4h, 6h, 8h, 10h, 12h, 14h, 16h, 18h, 20h. After the above-mentioned bulk polymerization, in-situ nucleated isotactic polybutene-1 is generated in the system.

[0081] In the present invention, after the bulk polymerization, the obtained reaction solution is preferably subjected to the following post-treatment: the unreacted butene-1 monomer is passed through the exhaust valve into a butene-1 recovery tank, and refined and recycled for reuse. After the above post-treatment, in-situ nucleated isotactic polybutene-1 is obtained.

[0082] The present invention also provides an in-situ nucleated isotactic polybutene-1 prepared by the preparation method described in the above technical solution. The in-situ nucleated isotactic polybutene-1 prepared by the above preparation method of the present invention has a low nucleating agent concentration of less than 500 ppm, especially 75-250 ppm; a crystallization temperature of more than 87°C, a crystallinity of more than 52%, and a crystal transformation period (transformation period from crystal form II to crystal form I) of less than 70 hours.

[0083] The preparation method provided by the present invention comprises the following steps: firstly, a main catalyst, a co-catalyst, a polymer nucleating agent monomer and a solvent are mixed and reacted to form a polymer nucleating agent in the system; then, a co-catalyst and an external electron donor are introduced, a liquid phase butene-1 monomer is added and hydrogen is introduced, and low-temperature bulk prepolymerization and room-temperature polymerization of butene-1 are directly performed to finally prepare in-situ nucleated polybutene-1 containing a low-concentration polymer nucleating agent, and the crystallization temperature and crystallinity of the in-situ nucleated polybutene-1 are improved and the crystal form transformation period is shortened, thereby realizing the low-cost preparation of isotactic polybutene-1 with excellent crystallization performance at a relatively low nucleating agent concentration.

[0084] The experimental results show that the content of the polymer nucleating agent in the in-situ nucleated polybutene-1 prepared by the present invention reaches below 500ppm, and the concentration of the nucleating agent is kept low, and the obtained isotactic polybutene-1 can have a higher crystallinity, crystallization temperature and a shorter crystal transformation period. Specifically, the product crystallization temperature reaches above 83°C, the crystallinity reaches above 48.5%, and the crystal transformation period is shortened to below 145h. Further, under preferred conditions, the concentration of the nucleating agent can be further reduced, specifically to below 250ppm (75-250ppm), and the crystallinity, crystallization temperature and crystal transformation period of the isotactic polybutene-1 product can be further improved, specifically, the product crystallization temperature is increased to above 87°C, the crystallinity is increased to above 52%, and the crystal transformation period is shortened to below 70h.

[0085] In order to further understand the present invention, preferred embodiments of the present invention are described below in conjunction with examples. However, it should be understood that these descriptions are only for further illustrating the features and advantages of the present invention, rather than limiting the claims of the present invention.

[0086] In the following examples and comparative examples, the main catalyst used is a commercially available magnesium chloride-supported titanium tetrachloride type, CS series from Liaoning Xiangyang Science and Technology Chemical Group Catalyst Company, with a titanium content of 2.3wt%. The reaction apparatus used is a 3L high-pressure polymerization kettle, and the distance between its stirring paddle and the bottom of the polymerization kettle is 1 to 3mm. The solvent used in step S1 is a solvent that has been refined to remove moisture and impurities.

[0087] Comparative Example 1

[0088] After the 3-liter autoclave was fully replaced with high-purity nitrogen, 100 mg of the main catalyst, 20 mL of the co-catalyst solution (the co-catalyst was triethylaluminum, the solvent was n-hexane, and the solution concentration was 1 mol / L), and 5 mL of the external electron donor solution (the external electron donor was diisobutyldimethoxysilane, the solvent was n-heptane, and the solution concentration was 0.2 mol / L) were added in sequence, and then 800 g of liquid butene-1 and 1 bar of hydrogen were added, and bulk prepolymerization was carried out at 0°C for 1 hour; finally, the reactor temperature was increased to 35°C, and the polymerization was continued for 4 hours to obtain polybutene-1.

[0089] Example 1

[0090] S1. After the 3-liter autoclave is fully replaced with high-purity nitrogen, 100 mg of the main catalyst, 0.5 mL of the co-catalyst solution (the co-catalyst is triethylaluminum, the solvent is n-hexane, and the solution concentration is 1 mol / L), 20 mg of vinyl cyclohexane (i.e., VCH, density 0.805 g / mL, purity ≥98%, water content ≤100 ppm), and 100 mL of n-hexane are added in sequence, and the polymerization is carried out at 30° C. for 10 hours. After the polymerization is completed, the reactor is kept at 30° C. and evacuated with a diaphragm vacuum pump to extract the solvent and separate to obtain material A.

[0091] S2. Lower the kettle temperature to 0°C, add 20 mL of co-catalyst solution (co-catalyst is triethylaluminum, solvent is n-hexane, solution concentration is 1 mol / L), 5 mL of external electron donor solution (external electron donor is diisobutyldimethoxysilane, solvent is n-heptane, solution concentration is 0.2 mol / L), then introduce 800 g of liquid butene-1 and 1 bar of hydrogen, and carry out bulk prepolymerization at 0°C for 1 hour.

[0092] S3. The reactor was heated to 35° C. and the polymerization was continued for 4 h to obtain in-situ nucleated polybutene-1.

[0093] Example 2

[0094] The method was carried out according to Example 1, except that the amount of VCH was adjusted to 50 mg.

[0095] Example 3

[0096] The method was carried out according to Example 1, except that the amount of VCH was adjusted to 100 mg.

[0097] Example 4

[0098] The method was carried out according to Example 1, except that the amount of VCH was adjusted to 150 mg.

[0099] Example 5

[0100] The process was carried out in accordance with Example 1, except that the amount of VCH was adjusted to 150 mg, and dicyclohexyldimethoxysilane was selected as the external electron donor.

[0101] Example 6

[0102] The process was carried out in accordance with Example 1, except that the amount of VCH was adjusted to 150 mg, and dicyclopentyldimethoxysilane was selected as the external electron donor.

[0103] Example 7

[0104] The process was carried out in accordance with Example 1, except that the amount of VCH was adjusted to 150 mg, and the reaction conditions in step S1 were polymerization at 20° C. for 15 h.

[0105] Example 8

[0106] The process was carried out in accordance with Example 1, except that the amount of VCH was adjusted to 150 mg, and the reaction conditions in step S1 were polymerization at 40° C. for 8 h.

[0107] Example 9

[0108] The process was carried out in accordance with Example 1, except that the amount of VCH was adjusted to 150 mg and the amount of the external electron donor solution was 2.5 mL.

[0109] Example 10

[0110] The process is carried out in accordance with Example 1, except that the temperature of the reactor is raised to 40° C. in step S3.

[0111] Example 11: Testing

[0112] 1. Test of polyvinylcyclohexane (PVCH) content in polymer: calculated by testing the conversion rate of vinylcyclohexane (VCH). In addition, the amount of VCH remaining in the reaction solution before separation of the solvent after the polymerization in step S1 was analyzed by gas chromatography; toluene was used as an internal standard. The residual amount of VCH in the above examples and comparative examples was 0.

[0113] 2. Melt flow rate (MFR) test: Determined in accordance with GB / T3682.1-2018, load 2.16 kg, test temperature 190 ° C.

[0114] 3. Test of isotacticity (DE-ins): It is determined by ether extraction method. 2g of dry polymer sample is placed in a Soxhlet extractor and extracted with boiling ether for 24 hours. The residue is dried to constant weight. The ratio of the polymer mass (g) to 2 (g) is the isotacticity.

[0115] 4. DSC test: In a nitrogen atmosphere, first heat 5-10 mg of sample from room temperature to 200°C at a rate of 10°C / min and keep at 200°C for 5 minutes to eliminate the thermal history; then cool the sample to room temperature at a rate of -10°C / min; finally, reheat the sample to 200°C at a rate of 10°C / min. Calculate the crystallization temperature (T) of the sample using the second heating curve according to the following relationship: c ) and crystallinity (X c ), melting point (T m ) is also measured according to the secondary heating curve: Xc (%) = ΔH m / ΔH * f 100%, where ΔH m is the melting enthalpy of the quadratic heating curve, ΔH * f It is the standard melting enthalpy of polybutene-1 form II (62 J / g).

[0116] 5. Test of catalytic activity: Calculate according to the following formula: CA = Q / W cat t×10 -3 , unit: kgPB·(gcat·h) -1 , where CA is the catalytic activity of the catalyst, Q is the mass of the polymerization product (g), W cat is the amount of main catalyst used (g), and t is the polymerization time of butene-1 (h).

[0117] 6. Crystal transformation period (t 90 ) test: The crystal form detection adopts wide angle X-ray diffraction (WAXD), and the test uses Cu target as the anode metal material, and the wavelength of Kα line generated is 0.154nm. The test voltage is 40kV, the current is 40mA, the scanning rate is 5° / min, and the scanning range is 5°-40°. The test sample is rapidly cooled from 200°C to 25°C at a rate of -50°C / min, and the samples with different annealing times are characterized at 25°C. In the WAXS test results, the diffraction peaks observed at 11.9°, 16.9° and 18.5° can be attributed to the (200), (220) and (213) crystal planes of polybutene-1 crystal form II, respectively; the diffraction peaks observed at 10.0°, 17.5° and 20.4° can be attributed to the (110), (300) and (220 / +211) crystal planes of polybutene-1 crystal form I, respectively. I and I(200) II Represent the integrated intensity of the diffraction peaks of Form I (110) and Form II (200), respectively. I / [I(110) I +0.67I(200)II ] represents the percentage of complete transformation of Form I (X I ), t 90 That is, after the polybutene-1 melt is cooled, the crystal form I completes 90% transformation (X I =90) time.

[0118] The test results are shown in Table 1:

[0119] Table 1: Butene-1 polymerization and polymer characterization results

[0120]

[0121] Note: VCH / Cat is the mass ratio of vinyl cyclohexane to the main catalyst; T is the VCH polymerization temperature; t is the VCH polymerization time; ED is the external electron donor, D1 is diisobutyldimethoxysilane, D2 is dicyclohexyldimethoxysilane, and D3 is dicyclopentyldimethoxysilane; ED / Ti=10 in Example 9, and ED / Ti=20 in other comparative examples; the bulk polymerization temperature of butene-1 in Example 10 is 40°C, and 35°C in other comparative examples.

[0122] It can be seen that Examples 1-10 and Comparative Example 1 all exhibit good catalytic activity, and the products all have high isotacticity.

[0123] The crystallization temperature is a good indicator of the efficiency of the nucleating agent, and a higher crystallization temperature means more effective nucleation in the final product. It can be seen from the test results in Table 1 that compared with Comparative Example 1, Examples 1 to 10 all exhibited a better nucleation effect, increasing the crystallization temperature of polybutene-1 from 72.3°C to above 83.2°C, and the crystallinity from 43.9% to above 48%, and the crystal transformation period was shortened to less than 145h.

[0124] Among Examples 1 to 10, Examples 2 to 10 are under preferred conditions (i.e., the mass ratio of polymer nucleating agent monomer: main catalyst is 0.5 to 1.5: 1), and the content of nucleating agent is increased, so that the crystallization temperature, crystallinity and crystal transformation period of the obtained isotactic polybutene-1 are further significantly improved, specifically, the product crystallization temperature is increased to above 87°C, the crystallinity is increased to above 52%, and the crystal transformation period is shortened to below 70h. In addition, compared with the crystal transformation period of Examples 2 to 10, the nucleating agent concentration of 29ppm only shortens the transformation period from 162h to 144h, and when the nucleating agent concentration exceeds 75ppm (but still maintained at a lower nucleating agent concentration of 250ppm), the crystal transformation period is greatly shortened to only 41 to 68h, proving that the above preferred parameter conditions have unexpectedly improved the crystal transformation period. Moreover, the nucleating agent concentration of Examples 2 to 10 of the present invention is below 250 ppm, which greatly reduces the nucleating agent concentration compared to the prior art, thereby achieving isotactic polybutene-1 with excellent crystallization performance at a lower nucleating agent concentration.

[0125] Specific examples are used herein to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core ideas, including the best mode, and also enable any technician in the field to practice the present invention, including making and using any device or system, and implementing any combined method. It should be pointed out that for ordinary technicians in this technical field, without departing from the principle of the present invention, the present invention can also be improved and modified, and these improvements and modifications also fall within the scope of protection of the claims of the present invention. The scope of patent protection of the present invention is defined by the claims and may include other embodiments that can be thought of by those skilled in the art. If these other embodiments have structural elements similar to the literal expression of the claims, or if they include equivalent structural elements that are not substantially different from the literal expression of the claims, then these other embodiments should also be included in the scope of the claims.

Claims

1. A method for preparing in-situ nucleated isotactic polybutene-1, characterized in that: The following steps are involved: a) 100 mg of a titanium tetrachloride spherical catalyst supported by magnesium chloride with a titanium content of 2.3 wt%, 0.5 mL of a 1 mol / L triethylaluminum n-hexane solution, 150 mg of vinyl cyclohexane and 100 mL of n-hexane are mixed for reaction, and then the n-hexane is removed to obtain material A; the reaction temperature is 20-40° C., and the reaction time is 8-15 h; b) mixing the material A with 20 mL of a 1 mol / L triethylaluminum n-hexane solution and 2.5-5 mL of a 0.2 mol / L external electron donor n-heptane solution, adding 800 g of liquid butene-1 monomer and introducing 1 bar of hydrogen, and performing butene-1 bulk prepolymerization at 0° C.; the external electron donor is selected from diisobutyldimethoxysilane, dicyclohexyldimethoxysilane or dicyclopentyldimethoxysilane; c) heating to 35-40° C. and performing bulk polymerization for 4 h to obtain in-situ nucleated isotactic polybutene-1; the content of the polymer nucleating agent in the polybutene-1 is 75-250 ppm.

2. An in-situ nucleated isotactic polybutene-1, characterized in that: Prepared by the preparation method described in claim 1.

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