CN114316110A - Production system and preparation method of propylene-butene random copolymer - Google Patents
Production system and preparation method of propylene-butene random copolymer Download PDFInfo
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Abstract
The invention relates to the technical field of olefin copolymerization, and discloses a production system and a preparation method of a propylene-butene random copolymer. The preparation method comprises the steps of carrying out a first gas-phase random copolymerization reaction on refined propylene and A-strand butene in the presence of a main catalyst, a cocatalyst, hydrogen, an external electron donor and an optional antistatic agent to obtain a first random copolymerization product; then contacting the first random copolymerization product with B-strand butene and optional hydrogen to carry out a second gas-phase random copolymerization reaction to obtain a product containing a propylene-butene random copolymer; wherein the mass ratio of the A-strand butene to the B-strand butene is 1: 0.1-0.6. The method can effectively reduce the melting temperature of the polymer and obtain the propylene-butylene binary random copolymer with low n-hexane extract content.
Description
Technical Field
The invention relates to the technical field of olefin copolymerization, in particular to a production system and a preparation method of a propylene-butene random copolymer.
Background
In recent years, the propylene-butene binary random copolymer has been increasingly emphasized, and many studies on the propylene-butene binary random copolymer have been reported. The butylene can achieve the effect of copolymerization modification of polypropylene by long-chain alpha-olefin, namely the crystallization of the polypropylene can be destroyed to reduce the glass transition temperature, the low-temperature toughness, the printing performance, the transparency and the processing performance of the polypropylene material are greatly improved, and the melting point and the initial heat sealing temperature of a polymer film material are reduced, so that the propylene-butylene binary random copolymer is widely used as a special sealing layer of a co-extruded film structure.
In the prior art, the production process of the propylene-butylene binary random copolymer has a wide selection range, and mainly comprises a gas phase method, a solution method, a solvent method, a liquid phase method and the like. The solution method and the solvent method are both to dissolve propylene and comonomer butylene in a solvent and to polymerize the propylene and the comonomer butylene in the solvent, and the subsequent solvent recovery process is complex, long in flow and high in energy consumption. The liquid phase method usually adopts a loop reaction kettle, and the propylene-butylene binary random copolymer generated by polymerization is easy to block pipelines, so that production stop is caused, and the production efficiency of enterprises is influenced. The problems of pipeline blockage and solvent recovery do not exist when the propylene-butylene binary random copolymer is prepared by adopting a gas phase method, but the content of butylene in the propylene-butylene binary random copolymer is difficult to control, and local hot spots are easily formed in a gas phase reaction to cause the propylene-butylene binary random copolymer to be agglomerated, so that the product performance is uneven, and the continuous and stable production cannot be realized.
Disclosure of Invention
The invention aims to overcome the problems of blocking of a propylene-butene binary random copolymer and low butene content in the propylene-butene binary random copolymer in a gas-phase reaction of propylene-butene copolymerization, and provides a production system and a preparation method of the propylene-butene random copolymer.
In order to achieve the above object, the present invention provides, in a first aspect, a process for preparing a propylene-butene random copolymer, the process comprising the steps of:
a. respectively refining raw material propylene and raw material butylene to obtain refined propylene and refined butylene, and dividing the refined butylene into A-strand butylene and B-strand butylene;
b. in the presence of a main catalyst, a cocatalyst, hydrogen, an external electron donor and an optional antistatic agent, carrying out a first gas-phase random copolymerization reaction on refined propylene and A-strand butene to obtain a first random copolymerization product;
c. contacting the first random copolymerization product with B-strand butene and optional hydrogen to carry out a second gas-phase random copolymerization reaction to obtain a product containing a propylene-butene random copolymer;
d. compressing and separating gas in a product containing the propylene-butene random copolymer to obtain liquid propylene and liquid butene, and returning the liquid propylene and the liquid butene to the step a for refining respectively;
wherein the mass ratio of the A-strand butene to the B-strand butene is 1: 0.1-0.6.
The second aspect of the present invention provides a production system of a propylene-butene random copolymer, comprising: a raw material refining unit, a copolymerization unit and a separation and recovery unit, wherein,
the raw material refining unit comprises a propylene refining unit and a butylene refining unit which are respectively used for refining raw material propylene and raw material butylene to obtain refined propylene and refined butylene;
the copolymerization unit comprises a first vertical gas-phase stirring kettle and a second vertical gas-phase stirring kettle which are connected in series, wherein the first vertical gas-phase stirring kettle is used for carrying out first gas-phase random copolymerization on refined propylene and refined butylene, and the second vertical gas-phase stirring kettle is used for carrying out second gas-phase random copolymerization on a product of the first gas-phase random copolymerization and the refined butylene to obtain a product containing a propylene-butylene random copolymer;
the separation and recovery unit is used for separating unreacted propylene and butylene in the product from the copolymerization unit, returning the separated propylene to the propylene refining unit, and returning the separated butylene to the butylene refining unit.
Through the technical scheme, the invention has the following beneficial effects:
(1) the invention takes propylene and butylene cracked by coal-based naphtha as raw materials, and the raw materials are refined by a polypropylene device and a polyethylene device and then undergo polymerization reaction. On the basis of the original polypropylene production device, the propylene-butylene binary random copolymer is produced by adopting a double vertical gas phase stirring reaction kettle which is independently designed and developed, and the restriction of the original process package is broken through by combining a polyethylene production device and a cracking device, so that the continuous production of the propylene-butylene binary random copolymer is realized.
(2) The production device of the propylene-butylene binary random copolymer does not need to additionally increase a recovery system and a raw material refining unit, and has less equipment investment and lower operation cost.
(3) The method can effectively introduce the butylene into the propylene-butylene random copolymer at a high polymerization rate, improve the content of butylene in the copolymer, and effectively reduce the melting temperature of the polymer to obtain the propylene-butylene binary random copolymer with low n-hexane extract content.
(4) The invention adopts the double vertical gas phase stirring reaction kettles to carry out propylene-butylene binary random copolymer, and butylene is respectively added into the two vertical gas phase stirring reaction kettles according to a certain mass ratio, so that block polymers can be effectively prevented from being generated in the polymerization process, and the device can stably run for a long time.
Drawings
FIG. 1 is a production system of a propylene-butene random copolymer provided by the present invention.
Description of the reference numerals
11. Propylene stripping tower 12, propylene desulfurizing tower 13 and propylene drying tower
14. Butene stripping tower 15, butene drying tower 31 and first vertical gas phase stirred tank
32. Second vertical gas phase stirred tank 33, discharge bin 41, carrier gas compressor arrangement
42. Carrier gas separation tower 43, low pressure depropanizer
Detailed Description
The endpoints of the ranges and any values disclosed herein are not limited to the precise range or value, and such ranges or values should be understood to encompass values close to those ranges or values. For ranges of values, between the endpoints of each of the ranges and the individual points, and between the individual points may be combined with each other to give one or more new ranges of values, and these ranges of values should be considered as specifically disclosed herein.
The present invention provides, in a first aspect, a process for preparing a propylene-butene random copolymer, the process comprising the steps of:
a. respectively refining raw material propylene and raw material butylene to obtain refined propylene and refined butylene, and dividing the refined butylene into A-strand butylene and B-strand butylene;
b. in the presence of a main catalyst, a cocatalyst, hydrogen, an external electron donor and an optional antistatic agent, carrying out a first gas-phase random copolymerization reaction on refined propylene and A-strand butene to obtain a first random copolymerization product;
c. contacting the first random copolymerization product with B-strand butene and optional hydrogen to carry out a second gas-phase random copolymerization reaction to obtain a product containing a propylene-butene random copolymer;
d. compressing and separating gas in a product containing the propylene-butene random copolymer to obtain liquid propylene and liquid butene, and returning the liquid propylene and the liquid butene to the step a for refining respectively;
wherein the mass ratio of the A-strand butene to the B-strand butene is 1: 0.1-0.6.
In the present invention, preferably, the mass ratio of the a-strand butene to the B-strand butene is 1: 0.1-0.3.
In the present invention, preferably, in step b, the amount of the a-butene is 8 to 10 parts by weight, the amount of the main catalyst is 0.004 to 0.01 part by weight, the amount of the cocatalyst is 0.02 to 0.03 part by weight, the amount of the hydrogen is 0.001 to 0.004 part by weight, and the amount of the external electron donor is 0.005 to 0.01 part by weight, relative to 100 parts by weight of the purified propylene.
In the present invention, preferably, in step b, the antistatic agent is mixed with an external electron donor and then added, and more preferably, the weight ratio of the antistatic agent to the external electron donor is 1: 1-2.
In the present invention, preferably, the antistatic agent is glyceryl monostearate and/or ethoxylated alkylamine; more preferably, the antistatic agent is an ethoxylated alkylamine; further preferably, the ethoxylated alkylamine is ethoxylated-C12-18-alkylamine (CAS: 72968-37-7).
In the present invention, preferably, in step b, the conditions of the first gas-phase random copolymerization reaction include: the temperature is 70-76 deg.C, preferably 73-75 deg.C, the pressure is 2-3MPa, preferably 2.5-2.8MPa, and the retention time is 1-2h, preferably 1-1.5 h.
In the present invention, preferably, in step c, the conditions of the second gas-phase random copolymerization reaction include: the temperature is 65-75 deg.C, preferably 70-73 deg.C, the pressure is 1.3-2MPa, preferably 1.5-1.8MPa, and the retention time is 0.5-1.5 hr, preferably 0.5-1 hr.
In the present invention, it is preferable that the hydrogen gas is used in an amount of 0.001 to 0.004 parts by weight per 100 parts by weight of the purified propylene in the step c.
In the present invention, preferably, the first gas-phase random copolymerization reaction and the second gas-phase random copolymerization reaction are each independently carried out under stirring, and more preferably, the rotation speed of the stirring is 20 to 30 rmp.
In the present invention, it is preferable that the pressure of the first gas-phase copolymerization reaction is higher than the pressure of the second gas-phase copolymerization reaction by 0.5 to 1MPa, preferably 0.5 to 0.8 MPa.
In the present invention, it is preferable that the temperature of the first gas-phase random copolymerization reaction is higher than the temperature of the second gas-phase random copolymerization reaction by 1 to 5 ℃.
In the present invention, it is preferable that the time of the first gas-phase random copolymerization reaction is longer than the time of the temperature of the second gas-phase random copolymerization reaction by 0.5 to 1 hour.
In the present invention, preferably, after the first gas-phase random copolymerization reaction and the second gas-phase random copolymerization reaction, the conversion rate of the refined propylene may reach 80 to 90%, and the conversion rate of the refined butene may reach 80 to 90%.
In the invention, the main catalyst is a commercial Ziegler/Natta catalyst, preferably, the effective components in the main catalyst comprise Ti, Mg, Cl and an internal electron donor, and the internal electron donor is phthalate, preferably phthalate. For example, the main catalyst is a CS-1 type catalyst produced by a commercial sunny plant.
In the invention, preferably, the main catalyst contains 1.5-3 wt% of titanium, 15-25 wt% of magnesium, 50-64 wt% of chlorine and 6-11 wt% of internal electron donor; more preferably, the main catalyst contains 2 wt% -3 wt% of titanium, 16 wt% -23 wt% of magnesium, 55 wt% -64 wt% of chlorine and 6 wt% -10 wt% of internal electron donor.
In the present invention, the cocatalyst is preferably an aluminum alkyl, preferably at least one of triethylaluminum, diethylaluminum chloride and triisobutylaluminum, more preferably triethylaluminum.
In the present invention, preferably, the external electron Donor is a non-phenyl siloxane, preferably cyclohexylmethyldimethoxysilane (CHMMS, Donor C), dicyclopentylmethyldimethoxysilane (DCPDMS, Donor D), bisisopropyldimethoxysilane (DIPMS, Donor P) and bisisobutyldimethoxysilane (DIBMS, Donor B), more preferably dicyclopentylmethyldimethoxysilane (Donor D).
In the present invention, preferably, the method further comprises a step e: granulating propylene-butylene random copolymer powder in a product containing the propylene-butylene random copolymer, wherein the granulating process comprises the steps of mixing the propylene-butylene random copolymer powder with a composite auxiliary agent and then granulating; more preferably, the granulation is carried out by adopting an extrusion granulation method, wherein the extrusion granulation method comprises the steps of extruding the mixture of the propylene-butene random copolymer powder and the composite auxiliary agent through an extruder at the melting temperature of 200-240 ℃, then granulating, and then cooling and granulating in a water bath at the temperature of 50-70 ℃ to obtain polymer granules.
In the present invention, preferably, the compounding aid includes a primary antioxidant, a secondary antioxidant, an acid scavenger, and optionally a polypropylene-based peroxide.
In the present invention, it is preferable that the amount of the primary antioxidant is 400-450mg, the amount of the secondary antioxidant is 850-950mg, and the amount of the acid acceptor is 290-350mg, per kg of the propylene-butene random copolymer powder.
In the present invention, it is preferable that the amount of the peroxide in the polypropylene-based peroxide is 100-200mg per kg of the propylene-butene random copolymer powder.
In the present invention, it is preferable that the primary antioxidant comprises hindered phenol-based antioxidants, wherein the hindered phenol-based antioxidants include 2, 6-di-t-butyl-4-methylphenol, n-octadecyl- β - (3, 5-di-t-butyl-4-hydroxyphenyl) propionate, pentaerythritol tetrakis [ β - (3, 5-di-t-butyl-4-hydroxyphenyl) propionate ] (i.e., antioxidant 1010), thiodiethylenebis [3- (3, 5-di-t-butyl-4-hydroxyphenyl) propionate, 1,3, 5-trimethyl-2, 4, 6-tris (3, 5-di-t-butyl-4-hydroxybenzyl) benzene, tris (2-methyl-4-hydroxy-5-t-butylphenyl) butane and 2, at least one of 2-methylenebis (4-methyl-6-tert-butylphenol); more preferably pentaerythritol tetrakis [ beta- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionate ].
In the present invention, preferably, the auxiliary antioxidant is a phosphite antioxidant including tris (2, 4-di-tert-butylphenyl) phosphite and/or p- (2, 4-di-tert-butylphenyl) pentaerythritol diphosphite. It is further preferable that tris (2, 4-di-tert-butylphenyl) phosphite is an auxiliary antioxidant.
In the present invention, preferably, the acid acceptor is hydrotalcite or calcium stearate ((C)17H35COO)2Ca). More preferably, the hydrotalcite adsorbs and fixes Cl "in stable crystals by anion exchange, and absorbs halogen ions remaining in a polypropylene polymerization stage in an extrusion granulation step after propylene polymerization, thereby improving the stability of polypropylene.
In the present invention, the peroxide in the polypropylene-based peroxide is preferably 2, 5-dimethyl-2, 5-di (t-butylperoxy) hexane, and more preferably, the content of the peroxide in the polypropylene-based peroxide is 10 to 20 wt%. The addition amount of the peroxide is small, so that the peroxide is prepared into the polypropylene-based peroxide in order to improve the dispersion uniformity of the peroxide in the mixing process of the propylene-butylene random copolymer and the composite auxiliary agent, and the polypropylene in the polypropylene-based peroxide is not particularly limited, can be commercially available polypropylene or polypropylene prepared according to the existing documents.
The second aspect of the present invention provides a production system of a propylene-butene random copolymer, comprising: a raw material refining unit, a copolymerization unit and a separation and recovery unit, wherein,
the raw material refining unit comprises a propylene refining unit and a butylene refining unit which are respectively used for refining raw material propylene and raw material butylene to obtain refined propylene and refined butylene;
the copolymerization unit comprises a first vertical gas-phase stirring kettle 31 and a second vertical gas-phase stirring kettle 32 which are connected in series, wherein the first vertical gas-phase stirring kettle 31 is used for carrying out first gas-phase random copolymerization on refined propylene and refined butylene, and the second vertical gas-phase stirring kettle 32 is used for carrying out second gas-phase random copolymerization on a product of the first gas-phase random copolymerization and the refined butylene to obtain a product containing a propylene-butylene random copolymer;
the separation and recovery unit is used for separating unreacted propylene and butylene in the product from the copolymerization unit, returning the separated propylene to the propylene refining unit, and returning the separated butylene to the butylene refining unit.
In the present invention, the product of the first gas-phase random copolymerization reaction is the product obtained from the first vertical gas-phase stirred tank 31. The product from the copolymerized units is the product of the propylene-butene-containing random copolymer.
In the embodiment provided by the present invention, the propylene refining unit may comprise a propylene stripping tower 11, a propylene desulfurization tower 12 and a propylene drying tower 13, preferably, the propylene stripping tower 11 is used for removing at least one of carbon monoxide, carbon dioxide and oxygen in the raw material propylene, the propylene desulfurization tower 12 is used for removing sulfur compounds in the propylene raw material, and the propylene drying tower 13 is used for removing water and/or alcohol in the propylene raw material.
In particular embodiments provided herein, the butene purification unit may include a butene stripping column 14 and a butene drying column 15. Preferably, the butene stripping column 14 is used to remove at least one of carbon monoxide, carbon dioxide and oxygen from the raw butene, and the butene drying column 15 is used to remove water from the butene raw material.
In the embodiment provided by the present invention, the first vertical gas-phase stirring tank 31 and the second vertical gas-phase stirring tank 32 are each provided with a stirrer independently.
In the specific embodiment provided by the present invention, the copolymerization unit may further include a discharge bin 33 for separating the propylene-butene random copolymer in the product from the copolymerization unit from a carrier gas including hydrogen, nitrogen, and unreacted propylene and butene.
In the embodiment provided by the present invention, the separation and recovery unit may include a carrier gas compression device 41, a carrier gas separation column 42, and a low pressure depropanizer column 43, wherein,
the carrier gas compression device 41 is used for compressing carrier gas and then sending the compressed carrier gas into the carrier gas separation tower 42;
the carrier gas separation tower 42 is used for separating a mixed liquid of propylene and butylene in the compressed carrier gas;
the low-pressure depropanizer 43 is used for separating a mixed solution of propylene and butylene to obtain propylene and butylene.
In the specific embodiment provided by the invention, the carrier gas compression device 41 compresses and boosts the carrier gas with the pressure of 0.1-0.2MPa to 3-4MPa, and then sends the compressed and boosted carrier gas to the carrier gas separation tower 42 for separation.
In the embodiment provided by the present invention, in the carrier gas separation column 42, hydrogen and nitrogen in the carrier gas are discharged as light components from the top of the carrier gas separation column, and a mixed liquid of propylene and butene is discharged as a heavy component from the bottom of the carrier gas separation column.
In the specific embodiment provided by the present invention, the operation conditions of the low-pressure depropanizer 43 can be the operation conditions commonly used in the field, and preferably, the tower top temperature of the low-pressure depropanizer is 5-20 ℃, the tower bottom temperature is 70-80 ℃, and the pressure is 0.6-0.9 MPa.
In the specific embodiment provided by the invention, the propylene refining unit can be a propylene refining unit in a polypropylene production system; the butene refining unit can be a butene refining unit in a polyethylene production system; the low pressure depropanizer can be a low pressure depropanizer in a petroleum cracking unit. Therefore, the increase of equipment and the increase of the input cost of production can be avoided.
The process for producing a propylene-butene random copolymer will be described below with reference to a schematic process flow diagram of the production system of a propylene-butene random copolymer of the present invention shown in FIG. 1.
Feeding raw material propylene into a propylene stripping tower 11 to remove impurities such as carbon monoxide, carbon dioxide and oxygen in the raw material propylene, then feeding the raw material propylene into a propylene desulfurizing tower 12 to remove impurities such as sulfur-containing compounds in the raw material propylene, and then feeding the raw material propylene into a propylene drying tower 13 to remove impurities such as water and/or alcohol in the raw material propylene to obtain refined propylene; meanwhile, the raw material butene is sent to a butene stripping tower 14 to remove impurities such as carbon monoxide, carbon dioxide and oxygen in the raw material butene, and then sent to a butene drying tower 15 to remove impurities such as water in the raw material butene to obtain refined butene, and the refined butene is divided into two strands. Feeding a main catalyst, a cocatalyst, hydrogen, an external electron donor, refined propylene and A-strand butene into a first vertical gas-phase stirring kettle 31 according to a mass ratio to perform a first gas-phase random copolymerization reaction to obtain a first random copolymerization product; and then the first random copolymerization product and the B-strand butene are sent into a second vertical gas-phase stirring kettle 32, a certain amount of hydrogen is added, and then a second gas-phase random copolymerization reaction is carried out to obtain a product containing the propylene-butene random copolymer. Sending the obtained product containing the propylene-butene random copolymer into a discharge bin 33 to separate propylene-butene random copolymer powder from gas in the product containing the propylene-butene random copolymer, feeding the separated propylene-butene random copolymer powder into an extrusion unit for granulation to obtain propylene-butene random copolymer particles, separating the gas through a carrier gas compression device 41, a carrier gas separation tower 42 and a low-pressure depropanizer 43 to obtain liquid propylene and liquid butene, returning the liquid propylene to a propylene stripping tower 11, and returning the liquid butene to a butene stripping tower 14.
The present invention will be described in detail below by way of examples. In the following examples of the present invention,
the main catalyst is a Ziegler/Natta catalyst with the model of CS-I, the manufacturer is a Yingkou sunny plant, and the main catalyst comprises the following effective components: 2.1 wt% of titanium, 18.9 wt% of magnesium, 59.1 wt% of chlorine and 6 wt% of internal electron donor (phthalate).
The manufacturer of polypropylene-based peroxide was Mannek corporation, and the content of 2, 5-dimethyl-2, 5-di (t-butylperoxy) hexane in polypropylene-based peroxide was 20 wt%.
The cocatalyst is triethyl aluminum.
The external electron donor is dicyclopentyl methyl dimethoxy silane.
The raw material propylene and the raw material butylene are derived from a coal-based naphtha cracking product.
Example 1
This example illustrates the preparation of a propylene-butene random copolymer
a. Feeding raw material propylene into a propylene stripping tower to remove impurities such as carbon monoxide, carbon dioxide and oxygen in the raw material propylene, then feeding the raw material propylene into a propylene desulfurizing tower to remove impurities such as sulfur-containing compounds in the raw material propylene, and then feeding the raw material propylene into a propylene drying tower to remove impurities such as water and/or alcohol in the raw material propylene to obtain refined propylene, wherein the composition of the refined propylene is shown in table 1; meanwhile, the butylene is sent to a butylene stripping tower to remove impurities such as carbon monoxide, carbon dioxide and oxygen in the raw material butylene, and then sent to a butylene drying tower to remove impurities such as water in the raw material butylene to obtain refined butylene, wherein the composition of the refined butylene is shown in table 2. And dividing the refined butene into two strands, wherein the mass ratio of the A-strand butene to the B-strand butene is 1: 0.1.
b. in the presence of a main catalyst, a cocatalyst, hydrogen and an external electron donor, feeding refined propylene and the A-strand butene into a first vertical gas-phase stirring kettle to perform a first gas-phase random copolymerization reaction to obtain a first random copolymerization product powder, wherein the A-strand butene is 10 parts by weight, the main catalyst is 0.007 parts by weight, the cocatalyst is 0.025 parts by weight, the hydrogen is 0.003 parts by weight and the external electron donor is 0.008 parts by weight, based on 100 parts by weight of the refined propylene; wherein, the external electron donor and the antistatic agent (ethoxylation-C12-18-alkylamine) are mixed according to the proportion of 1: 1 by weight ratio and then added. The conditions of the first gas-phase random copolymerization reaction include: the temperature was 75 ℃, the pressure 2.8MPa, the residence time 1.5h, and the stirring rate 29 rpm.
c. After the first gas-phase random copolymerization reaction is finished, intermittently and pressure-feeding the first random copolymerization product powder to a second reactor, feeding B-strand butene and hydrogen into a second vertical gas-phase stirring kettle, and carrying out a second gas-phase random copolymerization reaction by utilizing the residual activity of the first gas-phase stirring kettle to obtain a product containing the propylene-butene random copolymer. Wherein the amount of hydrogen used is 0.001 part by weight per 100 parts by weight of the purified propylene. The conditions of the second gas-phase copolymerization reaction include: the temperature is 70 ℃, the pressure is 1.8MPa, the retention time is 0.5h, and the speed of the stirrer is 29 rpm; and separating the product containing the propylene-butene random copolymer through a discharge bin to obtain propylene-butene random copolymer powder and gas.
d. And (b) compressing and separating the gas obtained by separating the discharge bin to obtain liquid propylene and liquid butene, and returning the liquid propylene and the liquid butene to the step a for refining respectively.
e. Uniformly mixing propylene-butene random copolymer powder, a main antioxidant (tetra [ beta- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionic acid ] pentaerythritol ester), an auxiliary antioxidant (tri (2, 4-di-tert-butylphenyl) phosphite) and an acid-absorbing agent (calcium stearate) through a spiral mixing device, conveying the mixture into an extrusion unit, extruding the mixture through an extruder at a melting temperature of 230 ℃, granulating the mixture, and cooling and granulating the mixture in a water bath at 60 ℃ to obtain propylene-butene random copolymer particles. Wherein, relative to each kilogram of propylene-butene random copolymer powder, the weight dosage of the main antioxidant is 440mg, the weight dosage of the auxiliary antioxidant is 890mg, and the weight dosage of the acid acceptor is 290 mg.
TABLE 1
| Components | Unit of | Raw material component specification |
| Propylene (PA) | mol％ | >99.6 |
| Methane | ppm(mol) | <100 |
| Propane | ppm(mol) | <0.4 |
| Ethane (III) | ppm(mol) | <200 |
| Ethylene | ppm(mol) | <10 |
| Acetylene | ppm(mol) | <0.5 |
| MAPD | ppm(mol) | <5 |
| Butadiene | ppm(mol) | <1 |
| Butene (butylene) | ppm(mol) | <10 |
| Carbon number of four or more | ppm(mol) | <10 |
| Hydrogen | ppm(mol) | <5 |
| Carbon monoxide | ppm(mol) | <0.05 |
| Carbon dioxide | ppm(mol) | <5 |
| Oxygen gas | ppm(mol) | 1.3 |
| Water (W) | ppm(mol) | 25 |
| Methanol | ppm(mol) | 4 |
| Chloride compound | ppm(mol) | 1 |
| Total sulfur (S) | ppm(mol) | <2 |
| Total carbonyl group | ppm(mol) | <1 |
| Oxide compound | ppm(mol) | <1 |
TABLE 2
Example 2
This example illustrates the preparation of a propylene-butene random copolymer
Propylene-butene random copolymer production was carried out in the same manner as in example 1, except that the mass ratio of the A-butene and B-butene was 1: 0.2.
example 3
This example illustrates the preparation of a propylene-butene random copolymer
Propylene-butene random copolymer production was carried out in the same manner as in example 1, except that the mass ratio of the A-butene and B-butene was 1: 0.3.
example 4
This example illustrates the preparation of a propylene-butene random copolymer
Propylene-butene random copolymer production was carried out in the same manner as in example 1, except that the mass ratio of the A-butene and B-butene was 1: 0.4.
example 5
This example illustrates the preparation of a propylene-butene random copolymer
Propylene-butene random copolymer production was carried out in the same manner as in example 1, except that the mass ratio of the A-butene and B-butene was 1: 0.5.
example 6
This example illustrates the preparation of a propylene-butene random copolymer
Propylene-butene random copolymer production was carried out in the same manner as in example 1, except that the mass ratio of the A-butene and B-butene was 1: 0.6.
example 7
This example illustrates the preparation of a propylene-butene random copolymer
Propylene-butene random copolymer production was carried out in the same manner as in example 2, except that, in the step b, hydrogen was used in an amount of 0.002 parts by weight; no hydrogen is added in step c; and e, adding polypropylene peroxide, wherein the dosage of the peroxide in the polypropylene peroxide is 100mg relative to each kilogram of propylene-butylene random copolymer powder.
Example 8
This example illustrates the preparation of a propylene-butene random copolymer
Propylene-butene random copolymer production was carried out in the same manner as in example 2, except that, in the step b, hydrogen was used in an amount of 0.002 parts by weight; no hydrogen is added in step c; and e, adding polypropylene peroxide, wherein the dosage of the peroxide in the polypropylene peroxide is 150mg per kg of the propylene-butylene random copolymer powder.
Example 9
This example illustrates the preparation of a propylene-butene random copolymer
Propylene-butene random copolymer production was carried out in the same manner as in example 2 except that the A-strand butene was used in an amount of 15 parts by weight based on 100 parts by weight of the amount of the purified propylene.
Example 10
This example illustrates the preparation of a propylene-butene random copolymer
a. Same as in example 1.
b. In the presence of a main catalyst, a cocatalyst, hydrogen and an external electron donor, feeding refined propylene and the A-strand butene into a first vertical gas-phase stirring kettle to perform a first gas-phase random copolymerization reaction to obtain a first random copolymerization product powder, wherein the A-strand butene is used in an amount of 8 parts by weight, the main catalyst is used in an amount of 0.005 part by weight, the cocatalyst is used in an amount of 0.03 part by weight, the hydrogen is used in an amount of 0.002 part by weight, and the external electron donor is used in an amount of 0.01 part by weight, relative to 100 parts by weight of the refined propylene; wherein, the external electron donor and the antistatic agent (ethoxylation-C12-18-alkylamine) are mixed according to the weight ratio of 2: 1 by weight ratio and then added. The conditions of the first gas-phase random copolymerization reaction include: the temperature was 73 ℃, the pressure 2.5MPa, the residence time 1h, and the stirring rate 20 rpm.
c. After the first gas-phase random copolymerization reaction is finished, intermittently and pressure-feeding the first random copolymerization product powder to a second reactor, feeding B-strand butene and hydrogen into a second vertical gas-phase stirring kettle, and carrying out a second gas-phase random copolymerization reaction by utilizing the residual activity of the first gas-phase stirring kettle to obtain a product containing the propylene-butene random copolymer. Wherein the amount of hydrogen used is 0.001 part by weight per 100 parts by weight of the purified propylene. The conditions of the second gas-phase copolymerization reaction include: the temperature is 70 ℃, the pressure is 1.5MPa, the retention time is 0.5h, and the speed of the stirrer is 20 rpm; and separating the product containing the propylene-butene random copolymer through a discharge bin to obtain propylene-butene random copolymer powder and gas.
d. And (b) compressing and separating the gas obtained by separating the discharge bin to obtain liquid propylene and liquid butene, and returning the liquid propylene and the liquid butene to the step a for refining respectively.
e. Uniformly mixing propylene-butene random copolymer powder, a main antioxidant (tetra [ beta- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionic acid ] pentaerythritol ester), an auxiliary antioxidant (tri (2, 4-di-tert-butylphenyl) phosphite) and an acid-absorbing agent (calcium stearate) through a spiral mixing device, conveying the mixture into an extrusion unit, extruding the mixture through an extruder at a melting temperature of 230 ℃, granulating the mixture, and cooling and granulating the mixture in a water bath at 60 ℃ to obtain propylene-butene random copolymer particles. Wherein, relative to each kilogram of propylene-butylene random copolymer powder, the weight dosage of the main antioxidant is 400mg, the weight dosage of the auxiliary antioxidant is 850mg, and the weight dosage of the acid acceptor is 320 mg.
Example 11
The preparation of a propylene-butene random copolymer was carried out as in example 2, except that no antistatic agent (ethoxylated-C12-18-alkylamine) was added in step b.
Example 12
Propylene-butene random copolymer preparation was carried out according to the procedure of example 2, except that the conditions of the first gas-phase random copolymerization reaction included: the temperature is 80 ℃, the pressure is 3.1MPa, the retention time is 1.5h, and the stirring speed is 29 rpm; the temperature of the second gas-phase random copolymerization reaction was 78 ℃ and the pressure was 2.5 MPa.
Example 13
Propylene-butene random copolymer preparation was carried out as in example 2, except that the ethoxylated-C12-18-alkylamine was replaced by an equal mass of glycerol monostearate.
Comparative example 1
This example illustrates the preparation of a propylene-butene random copolymer
Propylene-butene random copolymer production was carried out in the same manner as in example 1, except that the mass ratio of the A-butene and B-butene was 1: 1.
comparative example 2
The preparation of propylene-butene random copolymer was carried out in the same manner as in example 2 except that butene and hydrogen were fed only to the first vertical gas phase stirred tank and butene and hydrogen were not fed to the second vertical gas phase stirred tank, and the amount of butene fed to the first vertical gas phase stirred tank was the sum of the amounts of butene fed to the two reaction tanks in example 2 and the amount of hydrogen fed to the two reaction tanks in example 2.
Comparative example 3
Propylene-butene random copolymer preparation was carried out according to the procedure of example 2, except that both the A-butene and B-butene were replaced by equal masses of ethylene.
Test example 1
The melting point, molecular weight distribution and olefin content of the propylene-butene random copolymer powders obtained in step c of the above examples and comparative examples were measured, and the results are shown in Table 3.
The melting point is measured by a differential scanning method.
The method for testing the melt flow rate is a first part for determining the melt Mass Flow Rate (MFR) of the thermoplastic plastics GB/T3682.1-2018; the test conditions included: the test temperature was 230 ℃ and the nominal load was 2.16 kg.
The method for testing the molecular weight and the molecular weight distribution is high-temperature gel permeation chromatography, the mobile phase solvent is 1,2, 4-trichlorobenzene, the concentration is controlled to be 1mg/mL, the temperature is heated to 150 ℃, the solution is carried out for 3 hours, and the standard sample is monodisperse polystyrene.
The olefin content test method is a high-temperature 13CNMR test, wherein the solvent is dichlorodeuterobenzene, the temperature is 120 ℃, and the magnetic field frequency is 400 MHz.
TABLE 3
As can be seen from Table 3, the propylene-butene random copolymer having a higher butene content and a lower melting point can be produced by the process of the present invention, and thus the propylene-butene random copolymer prepared by the present invention has better processability. Meanwhile, the method of the invention does not produce block polymers in the polymerization process, so the method of the invention is more suitable for industrial production. Particularly preferably, by the methods of the invention using inventive examples 1-3 and example 10, a propylene-butene random copolymer having a butene content of 8 to 9% by weight and a melting point in the range of 146-148 ℃ can be obtained while ensuring that no bulk polymer is produced.
Test example 2
The propylene-butene random copolymer pellets obtained in step e of the above examples and comparative examples were subjected to a performance test, and the results are shown in Table 4.
The testing method of the cantilever beam impact strength is the measurement of the GBT 1843-2008 plastic cantilever beam impact strength.
The tensile yield strength was tested as described in GB/T1040.3-2006 test for tensile Properties of plastics part 3 test conditions for films and sheets.
The testing method of the flexural modulus is the testing of the flexural performance of the GB/T9341-2008 plastic.
The haze test method is GB/T2410-2008.
The heat distortion temperature is measured by GB/T1634.1-2004.
The test method of the n-hexane extract is GB/T5009.71-2003 analytical method of polypropylene resin hygienic standard for food packaging.
TABLE 4
As can be seen from the results in Table 4, the n-hexane extract content in the propylene-butene random copolymer particles prepared by the method of the present invention is significantly lower than the upper limit of 2% of n-hexane extract specified in the national standard polypropylene resin sanitation Standard for food packaging, so that the propylene-butene random copolymer particles prepared by the present invention can be used as transparent polypropylene random copolymer injection molding resin. In addition, the invention also ensures better comprehensive mechanical property and processing property of the propylene-butylene random copolymer particles under the condition of ensuring that the content of the n-hexane extract reaches the national standard.
As is clear from tables 3 and 4, the propylene-butene random copolymers having a high butene content and a low melting point were obtained by the methods of examples 7 to 8 of the present invention, but the propylene-butene random copolymers obtained by the methods had a high n-hexane extract content.
The preferred embodiments of the present invention have been described above in detail, but the present invention is not limited thereto. Within the scope of the technical idea of the invention, many simple modifications can be made to the technical solution of the invention, including combinations of various technical features in any other suitable way, and these simple modifications and combinations should also be regarded as the disclosure of the invention, and all fall within the scope of the invention.
Claims (10)
1. A process for the preparation of a propylene-butene random copolymer, characterized in that it comprises the following steps:
a. respectively refining raw material propylene and raw material butylene to obtain refined propylene and refined butylene, and dividing the refined butylene into A-strand butylene and B-strand butylene;
b. in the presence of a main catalyst, a cocatalyst, hydrogen, an external electron donor and an optional antistatic agent, carrying out a first gas-phase random copolymerization reaction on refined propylene and A-strand butene to obtain a first random copolymerization product;
c. contacting the first random copolymerization product with B-strand butene and optional hydrogen to carry out a second gas-phase random copolymerization reaction to obtain a product containing a propylene-butene random copolymer;
d. compressing and separating gas in a product containing the propylene-butene random copolymer to obtain propylene and butene, and returning the propylene and the butene to the step a for refining respectively;
wherein the mass ratio of the A-strand butene to the B-strand butene is 1: 0.1-0.6.
2. The method as claimed in claim 1, wherein in the step b, the butene of the A-strand is used in an amount of 8 to 10 parts by weight, the main catalyst is used in an amount of 0.004 to 0.01 part by weight, the cocatalyst is used in an amount of 0.02 to 0.03 part by weight, the hydrogen is used in an amount of 0.001 to 0.004 part by weight, and the external electron donor is used in an amount of 0.005 to 0.01 part by weight, based on 100 parts by weight of the refined propylene.
3. The process according to claim 1 or 2, wherein in step b, the conditions of the first gas-phase random copolymerization reaction comprise: 70-76 deg.C, preferably 73-75 deg.C, pressure of 2-3MPa, preferably 2.5-2.8MPa, and residence time of 1-2 hr, preferably 1-1.5 hr.
4. The process of any one of claims 1-3, wherein in step c, the conditions of the second gas-phase random copolymerization reaction comprise: the temperature is 65-75 deg.C, preferably 70-73 deg.C, the pressure is 1.3-2MPa, preferably 1.5-1.8MPa, and the retention time is 0.5-1.5 hr, preferably 0.5-1 hr.
5. The process according to any one of claims 1 to 4, wherein the pressure of the first gas-phase random copolymerization reaction is 0.5 to 1MPa, preferably 0.5 to 0.8MPa, higher than the pressure of the second gas-phase random copolymerization reaction.
6. The process according to any one of claims 1 to 5, wherein the temperature of the first gas-phase random copolymerization reaction is 1-5 ℃ higher than the temperature of the second gas-phase random copolymerization reaction.
7. The method as claimed in any one of claims 1 to 6, wherein the active components in the main catalyst comprise Ti, Mg, Cl and an internal electron donor, and the internal electron donor is phthalate, preferably phthalate;
and/or the cocatalyst is an aluminum alkyl, preferably at least one of triethylaluminum, diethylaluminum chloride and triisobutylaluminum, more preferably triethylaluminum;
and/or the external electron donor is a non-phenyl siloxane, preferably cyclohexylmethyldimethoxysilane, dicyclopentylmethyldimethoxysilane, bisisopropyldimethoxysilane and bisisobutyldimethoxysilane, more preferably dicyclopentylmethyldimethoxysilane.
8. The method of any of claims 1-7, wherein the antistatic agent is glycerol monostearate and/or ethoxylated alkyl amine;
and/or the weight ratio of the antistatic agent to the external electron donor is 1: 1-2;
preferably, the antistatic agent is an ethoxylated alkylamine.
9. The method according to any of claims 1-8, wherein the method further comprises step e: and granulating the propylene-butene random copolymer powder in the product containing the propylene-butene random copolymer, wherein the granulating process comprises the step of mixing the propylene-butene random copolymer powder with a composite auxiliary agent and then granulating.
10. A production system for a propylene-butene random copolymer, comprising: a raw material refining unit, a copolymerization unit and a separation and recovery unit, wherein,
the raw material refining unit comprises a propylene refining unit and a butylene refining unit which are respectively used for refining raw material propylene and raw material butylene to obtain refined propylene and refined butylene;
the copolymerization unit comprises a first vertical gas-phase stirring kettle (31) and a second vertical gas-phase stirring kettle (32) which are connected in series, the first vertical gas-phase stirring kettle (31) is used for carrying out first gas-phase random copolymerization on refined propylene and refined butylene, and the second vertical gas-phase stirring kettle (32) is used for carrying out second gas-phase random copolymerization on a product of the first gas-phase random copolymerization and the refined butylene to obtain a product containing a propylene-butylene random copolymer;
the separation and recovery unit is used for separating unreacted propylene and butylene in the product from the copolymerization unit, returning the separated propylene to the propylene refining unit, and returning the separated butylene to the butylene refining unit.
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| US20080188622A1 (en) * | 2007-02-01 | 2008-08-07 | Sumitomo Chemical Company, Limited | Propylene-based copolymer material, film made therefrom, and method for producing propylene-based copolymer material |
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