Long-chain alkenyl silane compound, and preparation method and application thereof

Abstract

The present application provides a long-chain alkenyl silane compound, a preparation method and application thereof. The long-chain alkenyl silane compound has the following general structure: [CH2=CH(CH2) n ] x Si[O(CH2) m CH3] 4‑x wherein n is an integer of 9-50; m is an integer of 0-4; and x is 1, 2 or 3.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of polyolefin synthesis, and in particular relates to long-chain alkenyl silane compounds and a method for preparing the same, and the use of the long-chain alkenyl silane compounds in the preparation of silane cross-linked polyolefins by copolymerization with olefins. BACKGROUND

[0002] Polyethylene (PE) is the most widely used synthetic resin, which has excellent dielectric properties, mechanical properties, good chemical stability, easy processing, low price and other characteristics. It is widely used to make plastic film, heat-resistant pipe, wire and cable, and various daily necessities. The macromolecular chain of polyethylene is linear or branched structure, and the intermolecular van der Waals force is weak. Generally, the crystalline phase and amorphous phase coexist in polyethylene, and the intermolecular interaction in the amorphous region is weak; when the temperature is high or the stress is large, the macromolecular chain of polyethylene is easy to slide, so the environmental stress cracking resistance and thermal stability of polyethylene are poor, which limits the application of polyethylene in many fields.

[0003] In order to improve the comprehensive performance of polyethylene and make it more widely used, people usually modify polyethylene, and the most common method is silane cross-linking modification. Silane cross-linking modification is to change the linear polyethylene molecular structure into a three-dimensional network structure by cross-linking, that is, to replace the van der Waals force with intermolecular chemical bonds, so that the mechanical properties, stress cracking resistance, heat deformation, deformation resistance and other properties of polyethylene are greatly improved, and the comprehensive performance of polyethylene is obviously improved. For this reason, gel content is an important indicator to characterize the cross-linking degree of polymer, and the higher the gel content, the more perfect the three-dimensional network formed by the polymer, and the more excellent the mechanical properties and weather resistance of the material.

[0004] Silane cross-linked polyethylene includes three different production methods. First, the first method is a two-step method, developed by the British Dow Corning Company (Dow Corning), also known as the Sioplas process. The specific steps are as follows: a small amount of peroxide initiator and silane coupling agent are mixed with polyethylene, and the mixture is mixed in a molten state to form a grafted A material; then the polyethylene mixed with the catalyst is melt extruded into a catalytic B material, the grafted A material and the catalytic B material are extruded into a certain proportion in a dry state, and then the product is placed in a water bath or water vapor for cross-linking molding. The two-step method of silane cross-linked polyethylene involves separate grafting and cross-linking, and the grafted A material and the catalytic B material are added in a certain proportion by physical blending, which has no special requirements for the extruder and is high in production efficiency. However, in the grafting reaction, a small amount of peroxide is introduced, so there are other side reactions in the reaction system, such as initiator-induced cross-linking of -C-C- in the polyethylene molecular chain. In addition, the grafting process will cause chain extension of the molecular chain, resulting in low processing fluidity, and even "shark skin" phenomenon during extrusion molding.

[0005] The second method is a one-step method. The one-step method is the Monosil process obtained by Maillefer Company and BICC (British Insulated Cable Company) in 1974, that is, the one-step method of silane cross-linked polyethylene. The one-step process is to mix dry polyethylene, peroxide initiator, silane coupling agent, catalyst and antioxidant together in a physical blending manner, then melt extrude in an extruder, and then water boil cross-linking to obtain the final product. The one-step method reduces the process flow, reduces the pollution of materials, and avoids the pre-crosslinking phenomenon caused by the storage process of the grafted material; but the equipment required by the one-step method is a special equipment, and it also needs supporting process technology and software technology, and the whole production process requires high.

[0006] The third method is the ethylene and silane copolymer method. This method is to place ethylene monomer and silane monomer in a high-pressure reaction kettle to prepare silane grafted polyethylene raw material, then melt blend the polyethylene with the catalyst to form a catalytic masterbatch, then the silane grafted polyethylene and the catalytic masterbatch are extruded into a certain proportion, and then hydrolyzed and condensed into silane cross-linked polyethylene. The material prepared by the ethylene silane copolymerization method has greatly improved storage stability, uniform ethylene silane copolymer monomer distribution, and corresponding improvement in heat resistance, corrosion resistance, mechanical properties, and molding processing stability, and the system contains less impurities, ensuring the cleanliness of the material.

[0007] At present, the research in the field of preparing crosslinked polyethylene by ethylene silane copolymerization has been lack of breakthrough in China. The main reason is that a suitable silane monomer has not been developed. In combination with the national conditions of polyethylene production in China, the silane monomer needs to have the following characteristics: 1. compatible with titanium-based and vanadium-based catalysts in terms of element composition, and does not cause the activity of the catalyst to decrease; 2. the group contained should have the copolymerization ability with ethylene and the crosslinking ability with other silane groups in structure; 3. the silane monomer itself should have good stability; 4. the synthesis of the silane monomer is simple, and the cost is controllable. SUMMARY

[0008] In view of the problems existing in the prior art, the present application provides a long-chain alkenyl silane compound, a preparation method thereof and a method for preparing silane crosslinked polyolefin by using the long-chain alkenyl silane compound.

[0009] The present application provides a long-chain alkenyl silane compound, which has the following general structure:

[0010] [CH2=CH(CH2) n ] x Si[O(CH2) m CH3] 4-x

[0011] wherein n is an integer of 9-50; m is an integer of 0-4; and x is 1, 2 or 3.

[0012] The present application also provides a preparation method of the long-chain alkenyl silane compound, which comprises the following steps:

[0013]

[0014] Step (1) is an esterification reaction of alkenyl carboxylic acid, wherein the alkenyl carboxylic acid is mixed with methanol, then a protonic acid is added as a catalyst, and heated to reflux to obtain an alkenyl ester;

[0015] Step (2) is a reaction of reducing the alkenyl ester into an alkenyl alcohol, wherein the alkenyl ester obtained in step (1) is dissolved in an organic solvent, and a reducing agent is added to react to obtain an alkenyl alcohol;

[0016] Step (3) is a reaction of converting the alkenyl alcohol into a halogenated olefin, wherein the alkenyl alcohol obtained in step (2) is azeotroped with a halogenating agent to obtain a halogenated olefin, wherein X represents halogen;

[0017] Step (4) is the preparation of a Grignard reagent;

[0018] Step (5) is a nucleophilic substitution reaction of Grignard reagent, in which tetraalkoxysilane is dissolved in an organic solvent and cooled to -50°C to -100°C, and then the Grignard reagent prepared in step (4) is slowly added dropwise to react, to obtain a long-chain alkenyl silane compound.

[0019] The present application also provides a method for preparing silane cross-linked polyolefin using the long-chain alkenyl silane compound, which comprises

[0020] Olefin copolymerization reaction with the long-chain alkenyl silane compound: into a nitrogen-substituted high-pressure reactor, sequentially add dried n-hexane, alkyl aluminum, long-chain alkenyl silane compound and titanium or vanadium olefin polymerization catalyst, and then introduce olefin to carry out olefin polymerization reaction, to obtain silane cross-linked polyolefin.

[0021] Advantages:

[0022] (1) When the method provided by the present application is used to prepare polymers, no additional catalyst blending is needed, and only simple heat treatment is needed to obtain cross-linked structure.

[0023] (2) When the method provided by the present application is used to prepare silane cross-linked polyolefin, only a small amount of long-chain alkenyl silane compound is needed to obtain a polymer with high gel content; and the gel content of the obtained polymer can be controlled by controlling the amount of the long-chain alkenyl silane compound added during polymerization, so that the cross-linking degree is controllable.

[0024] (3) When the polymerization reaction is carried out, the long-chain alkenyl silane compound provided by the present application added to the catalyst system will not affect the polymerization activity, and it is universal for titanium and vanadium olefin polymerization catalysts.

[0025] (4) The synthesis route of the long-chain alkenyl silane compound provided by the present application is simple, the raw materials are cheap, and no expensive metal catalyst is needed, so the preparation cost is low. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 The H-NMR spectrum of the long-chain alkenyl silane compound A-1 synthesized in the examples. 1 H-NMR spectrum. DETAILED DESCRIPTION

[0027] [Long-chain alkenyl silane compound]

[0028] As described above, the present application provides a long-chain alkenyl silane compound, which has the following general structure:

[0029] [CH2=CH(CH2) n ] x Si[O(CH2) mCH3] 4-x

[0030] wherein n is an integer of 9 to 50; m is an integer of 0 to 4; and x is 1, 2 or 3.

[0031] According to an embodiment of the present application, n is preferably an integer of 9 to 30, more preferably an integer of 9 to 20, for example, n can be 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19 or 20.

[0032] [Method for preparing long-chain alkenyl silane compound]

[0033] The present application also provides a method for preparing the above long-chain alkenyl silane compound, which comprises the following steps:

[0034]

[0035] Step (1) is an esterification reaction of alkenyl carboxylic acid, wherein alkenyl carboxylic acid is mixed with methanol, then a protonic acid is added as a catalyst, and heated to reflux to obtain an alkenyl ester;

[0036] Step (2) is a reaction of reducing alkenyl ester to alkenyl alcohol, wherein the alkenyl ester obtained in step (1) is dissolved in an organic solvent, and a reducing agent is added to react to obtain alkenyl alcohol;

[0037] Step (3) is a reaction of converting alkenyl alcohol to haloalkene, wherein the alkenyl alcohol obtained in step (2) is azeotroped with a halogenating agent to obtain haloalkene, wherein X represents halogen;

[0038] Step (4) is the preparation of Grignard reagent;

[0039] Step (5) is a nucleophilic substitution reaction of Grignard reagent, wherein tetraalkoxysilane is dissolved in an organic solvent and cooled to -50°C to -100°C, then the Grignard reagent prepared in step (4) is slowly added dropwise to react to obtain a long-chain alkenyl silane compound.

[0040] According to an embodiment of the present application, step (1) is an esterification reaction of alkenyl carboxylic acid. In the reaction process, alkenyl carboxylic acid is mixed with methanol, then a protonic acid is added as a catalyst, and heated to reflux to obtain an alkenyl ester.

[0041] In the step (1), the protonic acid catalyst can be selected from one or more of sulfuric acid, hydrochloric acid, phosphoric acid, p-toluenesulfonic acid.

[0042] In the step (1), the heating reflux time of the esterification reaction is 5 to 10 hours. The molar ratio of alkenyl carboxylic acid to methanol is 1:10 to 1:100.

[0043] According to an embodiment of the present application, step (2) is a reaction of reducing the alkenyl ester to an alkenyl alcohol. In the reaction, the alkenyl ester obtained in step (1) is dissolved in an organic solvent, a reducing agent is added, and the reaction is performed to obtain the alkenyl alcohol.

[0044] In the step (2), the organic solvent can be selected from one or more of methanol, ethanol, ethyl acetate, tetrahydrofuran, diethyl ether.

[0045] In the step (2), the reducing agent can be selected from one or more of sodium borohydride, potassium borohydride, lithium aluminum hydride, and sodium triacetoxyborohydride.

[0046] In the step (2), the reaction temperature is room temperature to 50°C, and the reaction time is 1 to 6 hours. The molar ratio of the alkenyl ester to the reducing agent is 1:1 to 1:4.

[0047] According to an embodiment of the present application, step (3) is a reaction of converting the alkenyl alcohol to a haloalkene. In the reaction, the alkenyl alcohol obtained in step (2) is azeotroped with a halogenating agent to obtain a haloalkene, wherein X represents a halogen selected from fluorine, chlorine, bromine, or iodine.

[0048] In the step (3), the halogenating agent can be one or more selected from the group consisting of dichlorosulfoxide, phosphorus trichloride, phosphorus pentachloride, liquid bromine, phosphorus tribromide, carbon tetrabromide, iodine, and potassium fluoride.

[0049] In the step (3), the reaction temperature is 40 to 80°C, and the reaction time is 1 to 5 hours. The molar ratio of the alkenyl alcohol to the halogenating agent is 1:1 to 1:1.5.

[0050] In the step (3), the reaction can be performed in the presence of an acid-binding agent for absorbing acidic gas generated in the reaction, thereby facilitating the reaction. Preferably, the acid-binding agent can be an organic base, preferably pyridine.

[0051] According to an embodiment of the present application, step (4) is the preparation of a Grignard reagent. The method of operation of this step can employ a conventional Grignard reagent preparation method in the art. For example, the Grignard reagent of the present application can be prepared by reacting the haloalkene with magnesium powder in anhydrous diethyl ether or tetrahydrofuran (THF). The generated Grignard reagent can be used directly in the subsequent reaction without separation.

[0052] According to an embodiment of the present application, step (5) is a nucleophilic substitution reaction of the Grignard reagent. In the reaction, tetraalkoxysilane is dissolved in an organic solvent and cooled to -50°C to -100°C, and then the Grignard reagent prepared in step (4) is slowly added dropwise to perform the reaction, thereby obtaining a long-chain alkenyl silane compound.

[0053] In the step (5), the organic solvent can be one or more selected from the group consisting of ether solvents, preferably tetrahydrofuran, diethyl ether, 1,4-dioxane.

[0054] In the step (5), the tetraalkoxysilane can be one or more selected from the group consisting of tetramethyl silicate, tetraethyl silicate (ethyl silicate), tetrabutyl silicate.

[0055] In the step (5), the cooling temperature is preferably -60°C to -80°C, and the reaction time is 10 minutes to 120 minutes. The molar ratio of the tetraalkoxysilane to the Grignard reagent is 20:1 to 1:3. In the present application, by controlling the molar ratio of the tetraalkoxysilane to the Grignard reagent, long-chain alkenyl silane compounds having different structures can be obtained. Specifically, when the tetraalkoxysilane is greatly excessive (>1:1), a product having x = 1 is mainly obtained; when the molar ratio of the tetraalkoxysilane to the Grignard reagent is 1:2, a product having x = 2 is mainly obtained; and when the molar ratio of the tetraalkoxysilane to the Grignard reagent is 1:3, a product having x = 3 is mainly obtained.

[0056] [Method for preparing silane cross-linked polyolefin]

[0057] The present application also provides a method for preparing a silane cross-linked polyolefin using the above long-chain alkenyl silane compound, which comprises a copolymerization reaction of an olefin and the long-chain alkenyl silane compound: a nitrogen-substituted high-pressure reaction vessel is sequentially charged with dried n-hexane, an alkyl aluminum, the long-chain alkenyl silane compound, and a titanium-based or vanadium-based olefin polymerization catalyst, and then olefin is introduced to perform an olefin polymerization reaction, thereby obtaining a silane cross-linked polyolefin.

[0058] In the copolymerization reaction, the olefin can be one or more selected from the group consisting of ethylene, propylene, 1-butene, butadiene, isobutylene, and isoprene.

[0059] In the copolymerization reaction, the alkyl aluminum can be one or more selected from the group consisting of trimethyl aluminum, triethyl aluminum, triisobutyl aluminum, methylaluminoxane, diethyl aluminum chloride, and ethyl aluminum dichloride.

[0060] In the copolymerization reaction, after the introduction of the olefin, the pressure of the reaction vessel is maintained at 0.1 to 1.0 MPa, the reaction temperature is controlled at 50 to 120°C, and the polymerization reaction time is 30 minutes to 150 minutes.

[0061] In the copolymerization reaction, the contents of the n-hexane, the alkyl aluminum, the long-chain alkenyl silane compound, and the titanium-based or vanadium-based olefin polymerization catalyst satisfy the following conditions:

[0062] The molar ratio of the aluminum element to the titanium element is 200:1 to 1000:1.

[0063] The molar ratio of aluminum element to vanadium element is 500:1-1000:1.

[0064] The amount of n-hexane added depends on the volume of the reactor, and is usually 40%-60% of the total volume of the reactor.

[0065] The concentration of the long-chain alkenyl silane compound added in the reactor is 0.02 mg / mL-1.00 mg / mL.

[0066] When the method provided by the present application is used to prepare silane cross-linked polyolefin, the gel content of the prepared polymer is as high as 8%-90%, preferably 8.5%-90%. This is because: the long-chain alkenyl silane compound designed and synthesized in the present application has more excellent copolymerization performance with olefin monomers than short-chain or medium-chain alkenyl silane, so that a polyolefin with high silane content can be obtained; at the same time, the longer carbon chain helps the movement of silane groups, so as to increase the probability of combination between silane groups, and condensation between silane groups occurs when heated, thereby forming a cross-linked network, which macroscopically forms polymer gel. That is, the high silane content and the high activity freedom of silane groups in the polymer together promote the high gel content of the finished polymer.

[0067] As can be seen, when the method provided by the present application is used to prepare silane cross-linked polyolefin, only a small amount (as low as 0.02 mg / mL-1.00 mg / mL) of long-chain alkenyl silane compound is needed to obtain a polymer with high gel content. Moreover, in the present application, the gel content of the obtained polymer can be controlled by controlling the amount of the long-chain alkenyl silane compound added during polymerization, so as to realize controllable cross-linking degree.

[0068] Examples

[0069] The technical solutions of the present application will be further described in detail below in combination with specific examples. It should be understood that the following examples are only illustratively used to explain and illustrate the present application, and should not be interpreted as limiting the scope of protection of the present application. Any technology realized based on the above description of the present application is covered within the scope of protection intended by the present application.

[0070] Unless otherwise specified, the raw materials and reagents used in the following examples are commercially available or can be prepared by known methods.

[0071] In the following examples, the catalyst used in the reaction for preparing silane cross-linked polyolefin using long-chain alkenyl silane compound is as follows:

[0072] Titanium-based catalyst: XY-S catalyst, purchased from Yingkou Xiangyang Catalyst Co., Ltd.;

[0073] Vanadium-based catalyst: VOCI3-AlEtCl2 complex, purchased from Sinopec Catalyst Oda Branch.

[0074] In addition, in the following examples, the polymer characterization methods are as shown below.

[0075] 1. The polymerization activity is calculated by taking ethylene as an example, which can be calculated by the following method:

[0076] The unit of polymerization activity is g PE / g Cat.h.

[0077]

[0078] 2. The determination of the gel content is carried out according to the provisions of JB / T10437-2004:

[0079] About 0.3 g of the polymer is weighed and hot-pressed at 200°C for 3 minutes to form a strip-shaped sample, which is then cut into pieces for use.

[0080] A stainless steel wire mesh with a hole width of 0.12 mm is cut into a square bag of about 40 mm x 40 mm and weighed (W1). The prepared sample is placed in the weighed stainless steel wire mesh bag, sealed and weighed (W2). The stainless steel wire mesh bag containing the sample is then placed in a round-bottom flask. A sufficient amount of xylene is added to the round-bottom flask to completely immerse the stainless steel wire mesh bag containing the sample. The sample is extracted in xylene for 12 h. After extraction, the mesh bag containing the sample is immediately placed in a vacuum oven preheated to 60°C to dry the sample to a constant weight, cooled and weighed (W3).

[0081] The gel content of the sample is calculated according to the following formula:

[0082] Gel content = (W3-W1) / (W2-W1)*100%

[0083] Preparation of long-chain alkenyl silane compounds

[0084] Preparation of long-chain alkenyl silane compounds A-1:

[0085]

[0086] (1) A 500 mL flask was charged with 10-undecenoic acid 100 g (0.54 mol), methanol 200 mL and concentrated sulfuric acid 1 mL, and refluxed for 6 hours. Post-treatment: the solvent was evaporated to dryness, and the product was separated by chromatography column, and finally 107 g of the target product 10-undecenoic acid methyl ester was obtained with a yield of 100%.

[0087] (2) Take a 1000 mL flask, add methyl 10-undecenoate 88 g (0.45 mol) and 300 mL of anhydrous ether, and cool to 0°C; then add lithium aluminum hydride 34.2 g (0.9 mol) in batches; finally, react at room temperature for 3 hours. Post-processing: quench the reaction with water, adjust the pH to about 5.0 with concentrated hydrochloric acid, extract with anhydrous ether, and finally separate using a chromatographic column to obtain the target product 10-undecenol 73.4 g with a yield of 96%.

[0088] (3) Take a 500 mL three-necked flask, add 10-undecenol 73.4 g (0.43 mol) and pyridine 39.5 g (0.45 mol), then add dichlorosulfoxide 59.5 g (0.45 mol) dropwise under nitrogen protection, and finally heat to 65°C for 2 hours. Post-processing: cool to room temperature, slowly add 100 mL of water, extract with ethyl acetate, wash the organic phase with 2M hydrochloric acid, and finally separate using a chromatographic column to obtain the target product 11-chloro-1-undecene 77.2 g with a yield of 95%.

[0089] (4) Weigh magnesium powder 5.76 g (0.24 mol) into a three-necked flask, and add 11-chloro-1-undecene 37.6 g (0.2 mol) in tetrahydrofuran dropwise under nitrogen protection (start with slight heating to complete initiation), and finally heat to reflux for 3 hours to complete the preparation of the Grignard reagent.

[0090] (5) Take a 1000 mL three-necked flask, add tetramethyl silicate 74 mL (0.5 mol) and 200 mL of tetrahydrofuran, cool to -78°C; then add the prepared Grignard reagent dropwise, react for 30 minutes, slowly warm to room temperature, and stir overnight. Post-processing: rotary evaporation to remove most of the solvent, then vacuum distillation to obtain the target product A-1 as 51.2 g with a yield of 95%. NMR characterization data are as follows: 1 H NMR (400 MHz, CDCl3) δ 5.81 (dd, J = 17.0, 10.3 Hz, 1H), 5.09-4.84 (m, 2H), 3.57 (s, 9H), 2.17-1.96 (m, 2H), 1.53-1.20 (m, 14H), 0.64 (dd, J = 9.1, 7.1 Hz, 2H).

[0091] Preparation Example 2 Synthesis of long-chain alkenyl silane compound A-2:

[0092]

[0093] Synthesis steps (1) to (4) are the same as compound A-1.

[0094] (5) A 1000 mL three-necked flask was charged with tetraethyl silicate 104 g (0.5 mol) and 200 mL of tetrahydrofuran, and cooled to -78°C. Then, the Grignard reagent prepared in step (4) of Preparation Example 1 was added dropwise, and reacted for 30 minutes. The temperature was slowly increased to room temperature, and stirred overnight. After-treatment: most of the solvent was removed by rotary evaporation, and then the target product A-3 was obtained by distillation under reduced pressure, in a yield of 62.7 g (99%). 1 H NMR (400 MHz, CDC13) δ 5.81 (dd, J = 17.0, 10.3 Hz, 2H), 5.09 - 4.84 (m, 4H), 3.57 (s, 6H), 2.17 - 1.96 (m, 4H), 1.53 - 1.20 (m, 28H), 0.64 (dd, J = 9.1, 7.1 Hz, 4H).

[0095] Preparation Example 3: Synthesis of long-chain alkenyl silane compound A-3

[0096]

[0097] Synthesis steps (1) to (4) were the same as those of compound A-1.

[0098] (5) A 1000 mL three-necked flask was charged with tetraethyl silicate 104 g (0.5 mol) and 200 mL of tetrahydrofuran, and cooled to -78°C. Then, the Grignard reagent prepared in step (4) of Preparation Example 1 was added dropwise, and reacted for 30 minutes. The temperature was slowly increased to room temperature, and stirred overnight. After-treatment: most of the solvent was removed by rotary evaporation, and then the target product A-3 was obtained by distillation under reduced pressure, in a yield of 62.7 g (99%). 1 H NMR (400 MHz, CDC13) δ 5.81 (dd, J = 17.0, 10.3 Hz, 2H), 5.09 - 4.84 (m, 4H), 3.57 (s, 6H), 2.17 - 1.96 (m, 4H), 1.53 - 1.20 (m, 28H), 0.64 (dd, J = 9.1, 7.1 Hz, 4H).

[0099] In the following examples and comparative examples, the n-hexane, the aluminum alkyl, the long-chain alkenyl silane compound, and the titanium-based or vanadium-based olefin polymerization catalyst used were all dried in advance using a conventional drying method before use.

[0100] Example 1

[0101] A 1 L reactor was heated and vacuumed, and replaced with nitrogen for 5 times; then 400 mL of n-hexane, 2 mL of triethylaluminum (0.8 M) and 10 mg of compound A-1 were added successively; after stirring for 10 minutes, 20 mg of XY-S catalyst (titanium-based catalyst) was added; the ethylene inlet valve was opened to maintain the reactor pressure at 0.4 MPa, and the reaction temperature was controlled at 80°C, and the polymerization reaction was carried out for 1 hour. The ethylene inlet valve was closed, and after filtration and drying, polymer 1 was obtained. The test results are shown in Table 1 below.

[0102] Example 2

[0103] A 1 L reactor was heated and vacuumed, and replaced with nitrogen for 5 times; then 400 mL of n-hexane, 2 mL of triethylaluminum (0.8 M) and 40 mg of compound A-1 were added successively; after stirring for 10 minutes, 20 mg of XY-S catalyst (titanium-based catalyst) was added; the ethylene inlet valve was opened to maintain the reactor pressure at 0.4 MPa, and the reaction temperature was controlled at 80°C, and the polymerization reaction was carried out for 1 hour. The ethylene inlet valve was closed, and after filtration and drying, polymer 2 was obtained. The test results are shown in Table 1 below.

[0104] Example 3

[0105] A 1 L reactor was heated and vacuumed, and replaced with nitrogen for 5 times; then 400 mL of n-hexane, 2 mL of triethylaluminum (0.8 M) and 80 mg of compound A-1 were added successively; after stirring for 10 minutes, 20 mg of XY-S catalyst (titanium-based catalyst) was added; the ethylene inlet valve was opened to maintain the reactor pressure at 0.4 MPa, and the reaction temperature was controlled at 80°C, and the polymerization reaction was carried out for 1 hour. The ethylene inlet valve was closed, and after filtration and drying, polymer 3 was obtained. The test results are shown in Table 1 below.

[0106] Example 4

[0107] A 1 L reactor was heated and vacuumed, and replaced with nitrogen for 5 times; then 400 mL of n-hexane, 2 mL of triethylaluminum (0.8 M) and 160 mg of compound A-1 were added successively; after stirring for 10 minutes, 20 mg of XY-S catalyst (titanium-based catalyst) was added; the ethylene inlet valve was opened to maintain the reactor pressure at 0.4 MPa, and the reaction temperature was controlled at 80°C, and the polymerization reaction was carried out for 1 hour. The ethylene inlet valve was closed, and after filtration and drying, polymer 4 was obtained.

[0108] The test results are shown in Table 1 below.

[0109] Example 5

[0110] A 1L reactor was heated and vacuumed, and replaced with nitrogen for 5 times; then 400 mL of n-hexane, 2 mL of triethylaluminum (0.8 M) and 320 mg of compound A-1 were added successively; after stirring for 10 minutes, 20 mg of XY-S catalyst (titanium-based catalyst) was added; the ethylene inlet valve was opened to maintain the reactor pressure at 0.4 MPa, and the reaction temperature was controlled at 80°C, and the polymerization reaction was carried out for 1 hour. The ethylene inlet valve was closed, and after filtration and drying, polymer 5 was obtained.

[0111] The test results are shown in Table 1 below.

[0112] Example 6

[0113] A 1L reactor was heated and vacuumed, and replaced with nitrogen for 5 times; then 400 mL of n-hexane, 2 mL of triethylaluminum (0.8 M) and 320 mg of compound A-1 were added successively; after stirring for 10 minutes, 20 mg of XY-S catalyst (titanium-based catalyst) was added; the ethylene inlet valve was opened to maintain the reactor pressure at 0.4 MPa, and the reaction temperature was controlled at 80°C, and the polymerization reaction was carried out for 1 hour. The ethylene inlet valve was closed, and after filtration and drying, polymer 5 was obtained.

[0114] The test results are shown in Table 1 below.

[0115] Example 7

[0116] A 1L reactor was heated and vacuumed, and replaced with nitrogen for 5 times; then 400 mL of n-hexane, 2 mL of triethylaluminum (0.8 M) and 320 mg of compound A-1 were added successively; after stirring for 10 minutes, 20 mg of XY-S catalyst (titanium-based catalyst) was added; the ethylene inlet valve was opened to maintain the reactor pressure at 0.4 MPa, and the reaction temperature was controlled at 80°C, and the polymerization reaction was carried out for 1 hour. The ethylene inlet valve was closed, and after filtration and drying, polymer 5 was obtained.

[0117] Example 8

[0118] A 1L reactor was heated and vacuumed, and replaced with nitrogen for 5 times; then 400 mL of n-hexane, 2 mL of triethylaluminum (0.8 M) and 320 mg of compound A-1 were added successively; after stirring for 10 minutes, 20 mg of XY-S catalyst (titanium-based catalyst) was added; the ethylene inlet valve was opened to maintain the reactor pressure at 0.4 MPa, and the reaction temperature was controlled at 80°C, and the polymerization reaction was carried out for 1 hour. The ethylene inlet valve was closed, and after filtration and drying, polymer 5 was obtained.

[0119] Comparative Example 1

[0120] A 1 L reactor was heated and vacuumed, and replaced with nitrogen for 5 times. Then 400 mL of n-hexane, 2 mL of triethylaluminum (0.8 M) were added in sequence. After stirring for 10 minutes, 20 mg of XY-S catalyst (titanium-based catalyst) was added. The ethylene inlet valve was opened to maintain the reactor pressure at 0.4 MPa, and the reaction temperature was controlled at 80°C, and the polymerization reaction was carried out for 1 hour. The ethylene inlet valve was closed, and the polymer 9 was obtained after filtration and drying. The test results are shown in Table 1 below.

[0121] Comparative Example 2

[0122] A 1 L reactor was heated and vacuumed, and replaced with nitrogen for 5 times. Then 400 mL of n-hexane, 2 mL of triethylaluminum (0.8 M) were added in sequence. After stirring for 10 minutes, 20 mg of VOCl3-AlEtCl2 complex (vanadium-based catalyst) was added. The ethylene inlet valve was opened to maintain the reactor pressure at 0.4 MPa, and the reaction temperature was controlled at 80°C, and the polymerization reaction was carried out for 1 hour. The ethylene inlet valve was closed, and the polymer 10 was obtained after filtration and drying. The test results are shown in Table 1 below.

[0123] Comparative Example 3

[0124] A 1 L reactor was heated and vacuumed, and replaced with nitrogen for 5 times. Then 400 mL of n-hexane, 2 mL of triethylaluminum (0.8 M) and 500 mg of vinyltrimethoxysilane (purchased from Beijing Inokai Company, purity 98%) were added in sequence. After stirring for 10 minutes, 20 mg of XY-S catalyst (titanium-based catalyst) was added. The ethylene inlet valve was opened to maintain the reactor pressure at 0.4 MPa, and the reaction temperature was controlled at 80°C, and the polymerization reaction was carried out for 1 hour. The ethylene inlet valve was closed, and the polymer 11 was obtained after filtration and drying. The test results are shown in Table 1 below.

[0125] Comparative Example 4

[0126] A 1 L reactor was heated and vacuumed, and replaced with nitrogen for 5 times. Then 400 mL of n-hexane, 2 mL of triethylaluminum (0.8 M) and 500 mg of 7-octenyltrimethoxysilane (purchased from Bluestar Silicones Technology Co., Ltd., purity 90%) were added in sequence. After stirring for 10 minutes, 20 mg of XY-S catalyst (titanium-based catalyst) was added. The ethylene inlet valve was opened to maintain the reactor pressure at 0.4 MPa, and the reaction temperature was controlled at 80°C, and the polymerization reaction was carried out for 1 hour. The ethylene inlet valve was closed, and the polymer 12 was obtained after filtration and drying. The test results are shown in Table 1 below.

[0127] Table 1. Characterization results of polymerization reaction

[0128]

[0129] From the results of Table 1, it can be seen that, in comparison of Examples 1-7 with Comparative Example 1, and Example 8 with Comparative Example 2, the long-chain alkenyl silane compound of the present application has little effect on the activity of the catalyst, i.e. it is universally applicable to both titanium-based and vanadium-based olefin polymerization catalysts, without degrading the catalytic activity, whether the titanium-based or vanadium-based olefin polymerization catalyst is used.

[0130] Furthermore, from Examples 1-5, it can be seen that, as the amount of the alkenyl silane compound of the present application added to the polymerization system is increased, the amount of gel formed in the polymer is gradually increased; thus, the gel content of the polymer can be controlled by controlling the amount of the long-chain alkenyl silane compound added.

[0131] In addition, from Examples 6, 7 and 8, it can be seen that, for both titanium-based and vanadium-based olefin polymerization catalysts, the compound having a long-chain alkenyl silane structure of the present application can achieve the preparation of a polymer having a high gel content.

[0132] In addition, from Comparative Examples 3 and 4, it can be seen that, even if a short-chain alkenyl silane (vinyltrimethoxysilane) or a medium-chain alkenyl silane (7-octenyltrimethoxysilane) is added in a very high amount, a polymer having a high gel content cannot be obtained, and the presence of these compounds in the polymerization system greatly reduces the activity of the catalyst.

[0133] In summary, the long-chain alkenyl silane compound provided by the present application has a simple and easy-to-implement synthesis method, and the target product can be synthesized in a very high yield; the long-chain alkenyl silane compound provided by the present application has no effect on the catalytic activity, whether for a titanium-based or a vanadium-based olefin polymerization catalyst; the technical solution provided by the present application can achieve the preparation of a silane crosslinked polymer, and the gel content of the polymer can be controlled by controlling the amount of the long-chain alkenyl silane compound added to the polymerization system.

[0134] The embodiments of the present application have been described above. However, the present application is not limited to the above-described embodiments. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1.A method for preparing silane-crosslinked polyolefin using long-chain alkenyl silane compound, the method comprising: copolymerization reaction of olefin and the long-chain alkenyl silane compound: sequentially adding dried n-hexane, alkyl aluminum, the long-chain alkenyl silane compound and titanium-based or vanadium-based olefin polymerization catalyst into a high-pressure reactor replaced by nitrogen, and then introducing olefin to perform olefin polymerization reaction, and obtaining silane-crosslinked polyolefin through filtration and drying; The long-chain alkenyl silane compound has the following general structure: wherein n is 9;m is an integer from 0 to 4;x is 1 or 2; The olefin is selected from one or more of ethylene, propylene, 1-butene, butadiene, isobutylene and isoprene; [CH2=CH(CH2) n ] x Si[O(CH2) m CH3] 4-x The alkyl aluminum is selected from one or more of trimethyl aluminum, triethyl aluminum, triisobutyl aluminum, methylaluminoxane, diethyl aluminum chloride and ethyl aluminum dichloride; In the copolymerization reaction, after introducing the olefin, the pressure of the reactor is maintained at 0.4-1.0 MPa, the reaction temperature is controlled at 80-120℃, and the polymerization reaction time is 30 minutes-150 minutes; In the copolymerization reaction, the content of the alkyl aluminum and the titanium-based or vanadium-based olefin polymerization catalyst satisfies the following conditions: the molar ratio of aluminum element to titanium element is 200:1-1000:1;the molar ratio of aluminum element to vanadium element is 500:1-1000:1; The concentration of the long-chain alkenyl silane compound added in the reactor is 0.02 mg / mL-1.00 mg / mL. The amount of n-hexane added is 40%-60% of the total volume of the reactor. ​ ​ ​ 2. The method of claim 1, wherein, ​

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