Antistatic composition and olefin polymerization method

Abstract

The present invention relates to a kind of antistatic composition and olefin polymerization method, the antistatic composition includes: oil-soluble hyperbranched polyamide-amine, oil-soluble surfactant and aliphatic hydrocarbon, wherein the molecular weight of oil-soluble hyperbranched polyamide-amine is 5000-40000;When used in olefin polymerization method, olefin, catalyst and the antistatic composition are added to polymerization reactor, polymerization reaction occurs, and polyolefin is obtained.When the antistatic composition of the present invention is used in olefin polymerization, oil-soluble hyperbranched polyamide-amine can neutralize and eliminate the negative static electricity generated by the friction between polyolefin particles and polymerization reactor wall, and the oil-soluble surfactant can fine-tune the positively charged initiation behavior of hyperbranched polyamide-amine, and the hyperbranched polyamide-amine molecules of the molecular weight cannot enter the micropore channel of the catalyst, thereby, not only can the anhydrous polymerization reactor be kept running at a low static level, but also the catalyst activity is less affected.

Description

Technical Field

[0001] The present invention relates to the technical field of olefin polymerization, and particularly to an antistatic composition and an olefin polymerization method. Background Art

[0002] In the industrial production of polyolefins, the high insulation of polyolefin particles and the dry and water-free reaction environment in the polymerization reactor cause the accumulation of static electricity generated during the polymerization reaction. When the static electricity is excessive, it is extremely easy to cause the adhesion and melting of the catalyst and polyolefin particles on the wall of the polymerization reactor, forming flakes and agglomerates. When the flakes and agglomerates fall off and enter the reaction zone, it will seriously interfere with the production smoothness in the polymerization reactor, block the product outlet, and ultimately force the polymerization reactor to stop production.

[0003] In order to control the problems of flaking and agglomeration caused by static electricity, more methods are to add antistatic substances to the polymerization reactor to reduce the generation of static electricity. For example, some technologies use alkyl diethanolamine as the antistatic substance, some technologies use linear ethylene oxide-propylene oxide copolymers as the antistatic substance, and some technologies use fatty acid esters, metal carboxylates or alkyl ammonium salts, etc. as the main active components of the antistatic composition. However, the antistatic principle of these antistatic substances is based on the hydrophilic group grabbing the environmental moisture, reducing the surface resistivity of the polyolefin, and thus accelerating the dissipation of static charges. Therefore, the charge dissipation effect of these antistatic substances faces challenges in the extremely water-free environment of the polymerization reactor, and often requires a relatively high addition amount to effectively inhibit static electricity. In addition, these antistatic substances will react or complex with the catalyst, resulting in a decrease in the activity of the catalyst, and the higher the addition amount of the antistatic substance, the more obvious the decrease in the catalyst activity. Summary of the Invention

[0004] Based on this, it is necessary to provide an antistatic composition and an olefin polymerization method for the above problems. When the antistatic composition is used in olefin polymerization, it can not only keep the water-free polymerization reactor operating at a low static electricity level, but also have a relatively low impact on the catalyst activity.

[0005] To achieve the above object, the technical solution adopted by the present invention is: an antistatic composition for olefin polymerization reaction, comprising: an oil-soluble hyperbranched polyamide-amine, an oil-soluble surfactant, and an aliphatic hydrocarbon, wherein the molecular weight of the oil-soluble hyperbranched polyamide-amine is 5000 - 40000.

[0006] In one embodiment, by mass fraction, the mass fraction of the oil-soluble hyperbranched polyamide-amine is 0.1% - 10%, the mass fraction of the oil-soluble surfactant is 5% - 30%, and the mass fraction of the aliphatic hydrocarbon is 60% - 94%.

[0007] In one embodiment, the oil-soluble hyperbranched polyamide-amine is selected from hyperbranched polyamide-amines having a structural formula as shown in formula (1).

[0008]

[0009] In formula (1), A is selected from H or A is a branching unit, and R is selected from H or an alkyl chain.

[0010] In one embodiment, the grafting rate of the alkyl chain is 5%-45%.

[0011] In one embodiment, the alkyl chain is selected from 10 -C 100 linear n-alkyl chains or C 10 -C 100 branched alkyl chains, or at least one of them.

[0012] In one embodiment, the oil-soluble surfactant is selected from at least one of alkyl sulfonic acids, alkyl amines, or alkyl amine sulfonic acids.

[0013] In one embodiment, the aliphatic hydrocarbon is selected from at least one of C 5 -C 20 linear paraffins, C 5 -C 20 branched paraffins, or C 5 -C 20 naphthenes.

[0014] An olefin polymerization method, in which an olefin, a catalyst, and the antistatic composition are added to a polymerization reactor to carry out a polymerization reaction to obtain an olefin polymer.

[0015] In one embodiment, based on the weight of the polyolefin in the polymerization reactor, the dosage of the antistatic composition is 2 ppmw-200 ppmw of the polyolefin.

[0016] In one embodiment, the catalyst is selected from at least one of metallocene catalysts, Ziegler-Natta catalysts, and chromium catalysts.

[0017] In the antistatic composition provided by the present invention, the oil-soluble hyperbranched polyamide-amine can adsorb on the surface of polyolefin particles and initiate positive charges on the surface of polyolefin particles through amine groups, which are used to neutralize and eliminate the negative static electricity generated by the friction between polyolefin particles and the wall of the polymerization reactor. The oil-soluble surfactant can fine-tune the positive charge initiation behavior of the hyperbranched polyamide-amine. Thus, under the synergistic action of the two, the anhydrous polymerization reactor can be maintained at a low static electricity level during operation.

[0018] Meanwhile, the molecular weight of the hyperbranched polyamide-amine of the present invention is 5,000 - 40,000. In this molecular weight range, the size of the spatial structure of the hyperbranched polyamide-amine molecule is 5 nm - 30 nm. The hyperbranched polyamide-amine molecules within this size range cannot enter the microporous channels of the catalyst, thus having a relatively small impact on the activity of the catalyst. Detailed Embodiments

[0019] To facilitate the understanding of the present invention, the present invention will be described in more detail below. However, it should be understood that the present invention can be implemented in many different forms and is not limited to the embodiments or examples described herein. On the contrary, the purpose of providing these embodiments or examples is to make the understanding of the disclosure content of the present invention more thorough and comprehensive.

[0020] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the technical field to which the present invention belongs. The terms used in the specification of the present invention herein are only for the purpose of describing specific embodiments or examples and are not intended to limit the present invention. The optional scope of the term "and / or" used herein includes any one of two or more related listed items, and also includes any and all combinations of the related listed items. The any and all combinations include any two related listed items, any more related listed items, or the combination of all related listed items.

[0021] The antistatic composition provided by the present invention is mainly used in olefin polymerization reactions. This antistatic composition does not rely on the water absorption performance of surfactants and is suitable for the anhydrous polymerization reactor environment.

[0022] Specifically, the antistatic composition includes an oil-soluble hyperbranched polyamide-amine, an oil-soluble surfactant, and an aliphatic hydrocarbon. Among them, the oil-soluble hyperbranched polyamide-amine can adsorb on the surface of polyolefin particles and initiate positive charges on the surface of polyolefin particles through amine groups, which are used to neutralize and eliminate the negative static electricity generated by the friction between polyolefin particles and the wall of the polymerization reactor. The oil-soluble surfactant can fine-tune the positive charge initiation behavior of the hyperbranched polyamide-amine. Thus, under the synergistic effect of the two, the anhydrous polymerization reactor can be maintained at a low static electricity level during operation.

[0023] Specifically, the molecular weight of the oil-soluble hyperbranched polyamide-amine of the present invention is 5,000 - 40,000. In this molecular weight range, the size of the spatial structure of the hyperbranched polyamide-amine molecule is 5 nm - 30 nm. The hyperbranched polyamide-amine molecules within this size range cannot enter the microporous channels of the catalyst, thus having a relatively small impact on the activity of the catalyst.

[0024] In order to improve the static electricity elimination and neutralization effects of the antistatic composition during the olefin polymerization process, in one embodiment, the hyperbranched polyamide-amine is selected from the hyperbranched polyamide-amine having the structural formula shown in formula (1).

[0025]

[0026] In formula (1), A is selected from H or A is a branched unit, and R is selected from H or an alkyl chain.

[0027] In order to improve the oil solubility of the hyperbranched polyamide-amine shown in formula (1), the grafting rate of the alkyl chain is 5%-45%, such as 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, etc., and the alkyl chain is selected from the straight-chain alkyl chain of C 10 -C 100 or at least one of the isoalkyl chains of C 10 -C 100 , such as the straight-chain alkyl chain or isoalkyl chain of C 10 , the straight-chain alkyl chain or isoalkyl chain of C 20 , the straight-chain alkyl chain or isoalkyl chain of C 40 , the straight-chain alkyl chain or isoalkyl chain of C 60 , the straight-chain alkyl chain or isoalkyl chain of C 80 , the straight-chain alkyl chain or isoalkyl chain of C 100 .

[0028] Optionally, the structural formula of the oil-soluble hyperbranched polyamide-amine is shown in formula (2), where R 1 is an alkyl chain of C 20 , the molecular weight is 280, the grafting rate is 10%, and the molecular weight of the whole hyperbranched polyamide-amine is 12500.

[0029]

[0030] In order to better fine-tune the positive charge initiation behavior of the hyperbranched polyamide-amine, in one embodiment, the oil-soluble surfactant is selected from at least one of alkyl sulfonic acids, alkyl amines or alkyl amine sulfonic acids. Among them, the alkyl sulfonic acids are selected from at least one of dodecylbenzenesulfonic acid or dinonylnaphthalenesulfonic acid, the alkyl amines are selected from at least one of lauryldimethyl tertiary amine, lauryltrimethyl ammonium chloride or tris(trimethylsilyl)amine, and the alkyl amine sulfonic acids are selected from at least one of lauryldimethyl sulfobetaine or tetradecyl sulfobetaine.

[0031] As a suitable solvent, in one embodiment, the aliphatic hydrocarbon is selected from the straight-chain alkanes of C 5 -C 20 , the straight-chain alkanes of C 5 -C 20At least one of isomeric paraffins or cycloalkanes of C 5 -C 20 such as isopentane, n-hexane, cyclohexane, n-heptane, n-octane.

[0032] In the antistatic composition of the present invention, by mass fraction, the mass fraction of the hyperbranched polyamide-amine is 0.1%-10%, the mass fraction of the oil-soluble surfactant is 5%-30%, and the mass fraction of the aliphatic hydrocarbon is 60%-94%. Specifically, the dosage of the antistatic composition introduced into the polymerization reactor can be adjusted according to the electrostatic level by monitoring the electrostatic level of the polymerization reactor.

[0033] Optionally, when the mass fraction of the hyperbranched polyamide-amine in the antistatic composition is higher, the oil solubility requirement is better. At this time, its oil solubility can be improved by further increasing the length of its alkyl chain and the grafting rate.

[0034] The present invention also provides an olefin polymerization method, in which olefins, a catalyst, and the antistatic composition as described above are added to a polymerization reactor to carry out a polymerization reaction to obtain an olefin polymer.

[0035] In order to further stabilize the static electricity in the polymerization reactor at a lower level, based on the weight of the polyolefin in the polymerization reactor, the dosage of the antistatic composition is 2 ppmw-200 ppmw of the polyolefin.

[0036] Since the antistatic composition provided by the present invention does not contain water and has a very low hydroxyl content, in one embodiment, the catalyst can be selected from at least one of metallocene catalysts, Ziegler-Natta catalysts, and chromium metal catalysts.

[0037] Hereinafter, the antistatic composition and the olefin polymerization method will be further described through the following specific examples.

[0038] I. Static elimination experiment

[0039] A cold model fluidized bed device was used to simulate the electrostatic behavior of polyolefin particles in a polymerization reactor. The cold model fluidized bed was a stainless steel cylinder with a diameter of 80 mm and a height of 800 mm, and the static bed height was 240 mm.

[0040] 400 g of polyethylene particles taken from an industrial fluidized bed polymerization reactor were added to ensure that the electrostatic behavior of the polyethylene particles was consistent with that of the industry. Pure nitrogen was used to fluidize the polyethylene particles at a gas velocity of 0.35 m / s for 1 h until the polyethylene particles were stably charged. Then, different weights of the antistatic composition were added above the distribution plate. After continuing to fluidize for 10 min, samples were taken near the distribution plate and the material level, and the charge-to-mass ratio was measured 5 times using the Faraday cylinder method, and the average value was taken. The results are shown in Table 1.

[0041] Example 1

[0042] Using the above cold model fluidized bed device and method, wherein, by mass fraction, the antistatic composition of this example comprises 1% of the hyperbranched polyamide-amine shown by the structural formula as formula (2), 5% of dodecylbenzenesulfonic acid and 94% of n-heptane.

[0043] Example 2

[0044] Using the above cold model fluidized bed device and method, wherein, by mass fraction, the antistatic composition of this example comprises 0.1% of the hyperbranched polyamide-amine shown by the structural formula as formula (2), 10% of tris(trimethylsilyl)amine and 89.9% of n-hexane.

[0045] Example 3

[0046] Using the above cold model fluidized bed device and method, wherein, by mass fraction, the antistatic composition of this example comprises 10% of hyperbranched polyamide-amine, 20% of dinonylnaphthalenesulfonic acid, 8% of lauryldimethyltertiary amine and 2% of lauryldimethylsulfobetaine and 60% of n-hexane.

[0047] Wherein, the structural formula of the used hyperbranched polyamide-amine is the same as formula (2), but R 1 is an alkyl chain of C 25 with a grafting rate of 35%, and the molecular weight of the whole hyperbranched polyamide-amine is 17,800.

[0048] Comparative Example 1

[0049] Using the above cold model fluidized bed device and method, wherein, by mass fraction, the antistatic composition of this comparative example comprises 10% of alkyldiethanolamine and 90% of n-heptane.

[0050] Comparative Example 2

[0051] Using the above cold model fluidized bed device and method, wherein, by mass fraction, the antistatic composition of this comparative example comprises 10% of dodecylbenzenesulfonic acid and 90% of n-heptane.

[0052] Comparative Example 3

[0053] Using the above cold model fluidized bed device and method, wherein, by mass fraction, the antistatic composition of this comparative example comprises 1% of the hyperbranched polyamide-amine shown by the structural formula as formula (2) and 99% of n-heptane.

[0054] Table 1

[0055]

[0056] As can be seen from Table 1, in Comparative Example 1 and Comparative Example 2, conventional surfactants were used as the main antistatic active substances, and their static electricity dissipation effects were poor in an anhydrous environment. Additive amounts of 200 ppmw and 400 ppmw were respectively required to control the static electricity at a low level. Among them, the alkyldiethanolamine in Comparative Example 1 contained an amino group, so the final static electricity dissipation effect showed a positive charge, while the dodecylbenzenesulfonic acid in Comparative Example 2 contained a sulfonic acid group, so the final static electricity dissipation effect showed a negative charge. In Comparative Example 3, hyperbranched polyamide-amine was used as the main antistatic active substance, which had a high amino group ratio and was extremely likely to induce a positive charge on the surface of polyolefin particles. At an additive amount of 25 ppmw, the negative static electricity could be basically neutralized and eliminated. However, when the antistatic composition was added in excess, that is, more than 50 ppmw, the static electricity polarity of the particles reversed to positive and increased sharply, making it difficult to maintain a stable low-static state during operation. In the antistatic composition of Example 1, hyperbranched polyamide-amine was compounded with dodecylbenzenesulfonic acid (i.e., an oil-soluble surfactant). Under their interaction, the static electricity in the anhydrous polymerization reactor could be efficiently maintained at a low level. In Example 2, a lower concentration of hyperbranched polyamide-amine and tris(trimethylsilyl)amine were used, which could slowly eliminate the negative static electricity, and this formulation had a high operation error tolerance when regulating the static electricity in the polymerization reactor. In Example 3, a higher concentration of hyperbranched polyamide-amine was used, and it was compounded with alkyl sulfonic acid, alkyl amine, and alkyl amine sulfonic acid, which could more efficiently eliminate the negative static electricity and maintain the static electricity at a low level state.

[0057] II. Olefin Polymerization Experiment

[0058] Comparative Example 1

[0059] In a 2L glass reactor, ethylene polymerization reaction was carried out using a metallocene catalyst. The specific operation was as follows:

[0060] Place the glass reactor in an oven and heat it at 105°C for 2 hours to ensure that the glass reactor is in an anhydrous reaction environment. Then heat the glass reactor in an oil bath to 80°C, evacuate the glass reactor and replace the gas with high-purity nitrogen. This process was repeated 3 times, and then replace the high-purity nitrogen with ethylene gas and repeat the above operation 3 times.

[0061] Add 86.4 g of the catalyst promoter methylaluminoxane (20 wt% toluene solution) to the glass reactor. Then dissolve the commercial metallocene catalyst bis(1-butyl-3-methylcyclopentadienyl)zirconium dichloride in 260 mL of toluene and inject it into the glass reactor and stir for 1 minute. Then raise the ethylene pressure to 0.5 MPa and carry out a 1-hour polymerization reaction. Slowly add acidified ethanol to the product to terminate the reaction, filter by suction, and vacuum dry at 60°C for 24 hours.

[0062] Example 1

[0063] The difference between Example 1 and Comparative Example 1 is only that, based on the weight of the polyethylene particles in the glass reactor, 25 ppmw of an antistatic composition based on the weight of the polyethylene particles is incorporated into the metallocene catalyst. Among them, by mass fraction, the antistatic composition comprises 1% of a hyperbranched polyamide-amine having the structural formula shown in Formula (2), 5% of dodecylbenzenesulfonic acid, and 94% of n-heptane.

[0064] Example 2

[0065] The difference between Example 2 and Comparative Example 1 is only that, based on the weight of the polyethylene particles in the glass reactor, 25 ppmw of an antistatic composition based on the weight of the polyethylene particles is incorporated into the metallocene catalyst. Among them, by mass fraction, the antistatic composition comprises 10% of a hyperbranched polyamide-amine, 20% of dinonylnaphthalenesulfonic acid, 8% of lauryldimethylamine, 2% of lauryldimethylsulfobetaine, and 60% of n-hexane. The structural formula of the hyperbranched polyamide-amine used is the same as that shown in Formula (2), but R 1 is an alkyl chain of C 25 with a grafting rate of 35% and the molecular weight of the whole hyperbranched polyamide-amine is 17,800.

[0066] The catalyst activity tests of Example 1, Example 2 and Comparative Example 1 are shown in Table 2.

[0067] Table 2

[0068]

[0069] As can be seen from Table 2, the catalyst activity in Comparative Example 1 is 8300 gPE / (gCat-hr) -1 , the catalyst activity in Example 1 is 8180 gPE / (gCat-hr), and the catalyst activity in Example 2 is 8160 gPE / (gCat-hr). It can be seen that the addition of the antistatic composition only reduces the activity of the catalyst by 1.4% and 2.5% respectively, with a relatively small impact.

[0070] Comparative Example 2

[0071] The ethylene polymerization reaction was carried out using a Ziegler-Natta catalyst in a 1.1 L stainless steel autoclave reactor. The specific operation is as follows:

[0072] The stainless-steel autoclave reactor was evacuated and heated to 95 °C and maintained for 3 h, then cooled to 75 °C by the constant-temperature circulating water in the jacket, 400 mL of n-heptane was injected, and the catalyst promoter triethylaluminum was first injected under a nitrogen atmosphere, then the Ziegler-Natta catalyst was added, and the stainless-steel autoclave reactor was maintained at a pressure of 0.8 MPa and polymerized for 1 h under continuous injection of ethylene. The synthesized polyethylene particles were immediately washed with acidified ethanol and vacuum-dried at 60 °C for 24 h.

[0073] Example 3

[0074] The difference between this Example 3 and Comparative Example 2 is only that, based on the weight of the polyethylene particles in the stainless-steel autoclave reactor, 25 ppmw of an antistatic composition is mixed into the Ziegler-Natta catalyst. Among them, by mass fraction, the antistatic composition includes 1% of hyperbranched polyamide-amine with the structural formula shown in Formula (2), 5% of dodecylbenzenesulfonic acid, and 94% of n-heptane.

[0075] Example 4

[0076] The difference between this Example 4 and Comparative Example 2 is only that, based on the weight of the polyethylene particles in the stainless-steel autoclave reactor, 25 ppmw of an antistatic composition is mixed into the Ziegler-Natta catalyst. Among them, by mass fraction, the antistatic composition of this example includes 0.1% of hyperbranched polyamide-amine with the structural formula shown in Formula (2), 10% of tris(trimethylsilyl)amine, and 89.9% of n-hexane.

[0077] The catalyst activity tests of Example 3, Example 4 and Comparative Example 2 are shown in Table 3.

[0078] Table 3

[0079]

[0080] As can be seen from Table 3, the catalyst activity in Comparative Example 2 is 1080 gPE / (gCat-hr) -1 , the catalyst activity in Example 3 is 1050 gPE / (gCat-hr), and the catalyst activity in Example 4 is 1060 gPE / (gCat-hr). It can be seen that the addition of the antistatic composition only reduces the activity of the catalyst by 2.8% and 1.9% respectively, and the influence is small.

[0081] The technical features of the above-described embodiments and examples can be combined in any suitable manner. For the sake of brevity of description, not all possible combinations of the technical features in the above-described embodiments and examples are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered to be within the scope described in this specification.

[0082] The above-described embodiments merely represent several implementation manners of the present invention, facilitating the specific and detailed understanding of the technical solution of the present invention. However, it should not be construed as a limitation on the protection scope of the invention patent. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several deformations and improvements can be made, and these all fall within the protection scope of the present invention. In addition, it should be understood that after reading the above teachings of the present invention, those skilled in the art can make various changes or modifications to the present invention, and the equivalent forms obtained also fall within the protection scope of this application. It should also be understood that the technical solutions obtained by those skilled in the art through logical analysis, reasoning or limited experiments based on the technical solution provided by the present invention are all within the protection scope of the appended claims of the present invention. Therefore, the protection scope of this invention patent shall be subject to the content of the appended claims, and the specification can be used to interpret the content of the claims.

Claims

1. An antistatic composition for olefin polymerization, characterized in that, it comprises: an oil-soluble hyperbranched polyamide-amine, an oil-soluble surfactant, and an aliphatic hydrocarbon, wherein the molecular weight of the oil-soluble hyperbranched polyamide-amine is 5000 - 40000, and the oil-soluble hyperbranched polyamide-amine is selected from the hyperbranched polyamide-amine shown by the structural formula as formula (1), In formula (1), A is selected from H or A is a branched unit, R is selected from H or an alkyl chain, the grafting rate of the alkyl chain is 5%-45%, and the alkyl chain is selected from at least one of a normal alkyl chain of C 10 -C 100 and an isomeric alkyl chain of C 10 -C 100 ; by mass fraction, the mass fraction of the oil-soluble hyperbranched polyamide-amine is 0.1% - 10%, the mass fraction of the oil-soluble surfactant is 5% - 30%, and the mass fraction of the aliphatic hydrocarbon is 60% - 94%.

2. The antistatic composition according to claim 1, characterized in that, the oil-soluble surfactant is selected from at least one of alkyl sulfonic acids, alkyl amines, or alkyl amine sulfonic acids.

3. The antistatic composition according to claim 1, characterized in that, The aliphatic hydrocarbon is selected from at least one of 5 -C 20 n-alkanes of 5 -C 20 isoalkanes of 5 -C 20 cycloalkanes of 4. An olefin polymerization method, characterized in that, an olefin, a catalyst, and the antistatic composition according to any one of claims 1 - 3 are added to a polymerization reactor to carry out a polymerization reaction to obtain a polyolefin.

5. The olefin polymerization method according to claim 4, characterized in that, based on the weight of the polyolefin in the polymerization reactor, the dosage of the antistatic composition is 2 ppmw - 200 ppmw of the polyolefin.

6. The olefin polymerization method according to claim 4, characterized in that, the catalyst is selected from at least one of metallocene catalysts, Ziegler-Natta catalysts, and chromium metal catalysts.

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