Method for the melt process catalytic preparation of post-functionalized polyolefins and use thereof

Abstract

The application discloses a method for preparing post-functionalized polyolefin by melt method and synergistic catalysis, and belongs to the technical field of polymer material modification. m The grafting reaction is carried out, extrusion and cooling are performed, and the post-functionalized polyolefin is obtained; wherein the catalyst is selected from the combination of tert-butyl nitrite and N-hydroxyphthalimide. The application realizes efficient and high-selectivity graft modification of the polyolefin under the melt processing condition by utilizing the synergistic catalysis of tert-butyl nitrite and N-hydroxyphthalimide, effectively inhibits degradation side reactions, and maintains excellent performance of the base material.

Description

Technical Field

[0001] This invention belongs to the field of polymer material modification technology, and particularly relates to a method for preparing post-functionalized polyolefins by melt synergistic catalysis and its application. Background Technology

[0002] Polyolefin materials, mainly including polyethylene (PE) and polypropylene (PP), have become indispensable basic materials in various fields due to their excellent comprehensive properties, low price, and good processability. However, the molecular chains of polyolefins are entirely composed of non-polar carbon-carbon and carbon-hydrogen bonds. This chemical inertness results in poor hydrophilicity, low surface energy, and poor compatibility with polar substances, making it difficult to meet the urgent needs of high-end applications for material functionalization (such as antibacterial, flame retardant, adhesive, printing and dyeing, and antistatic properties).

[0003] To address the aforementioned issues, various functionalization modification strategies for polyolefins have been developed in this field. Among them, post-functionalization modification technology, which involves chemical grafting modification of synthesized polyolefins, has become a hot topic of common interest in both industry and academia because it can achieve functional upgrades of materials without altering the existing polymerization production system.

[0004] Depending on the reaction medium, post-functionalization modification can be divided into solution-based and melt-based methods. Solution-based methods offer mild reaction conditions and facilitate mechanism research, but require large amounts of organic solvents, resulting in complex subsequent processing, significant environmental impact, and high production costs, making them unsuitable for large-scale industrial production. In contrast, melt-based methods involve grafting reactions directly during polymer melt processing, eliminating the need for solvents. The process is simple and can be seamlessly integrated with existing extrusion and injection molding equipment, offering significant advantages such as high efficiency, low cost, and environmental friendliness. Therefore, it is the preferred route for the industrial application of polyolefin functionalization modification.

[0005] Currently, the widely used industrial melt grafting technology mainly relies on peroxide initiators (such as dicumyl peroxide (DCP) and benzoyl peroxide (BPO)) to initiate free radical grafting reactions. However, these traditional initiation systems have inherent defects in the high-temperature, high-shear environment of melt processing: high free radical activity and poor selectivity. While initiating the grafting reaction, they easily induce β-fracture of the polyolefin backbone (leading to a significant decrease in molecular weight and deterioration of mechanical properties) or coupling and crosslinking between macromolecular chains (leading to gel formation and deterioration of processing performance). In addition, the high viscosity and uneven mixing of the melt system, along with the rapid and difficult-to-control decomposition of traditional initiators, often result in grafting reactions limited to local areas, poor grafting uniformity, and large fluctuations in product quality. How to achieve highly selective and controllable grafting of polyolefins under the harsh conditions of high temperature, high shear, and solvent-free melt processing has always been a core technical bottleneck that those skilled in the art are striving to overcome.

[0006] It is worth noting that the direct functionalization of carbon-hydrogen bonds (CH bonds) has always been a research frontier and hot topic in the field of small molecule organic synthesis. In recent years, tert-butyl nitrite (TBN), as a green and efficient free radical initiator and nitrating agent, has been widely used in the activation and transformation of small molecule CH bonds. Studies have shown that TBN can decompose under heating conditions to generate tert-butoxy radicals and nitric oxide (NO), which can work synergistically to achieve selective hydrogen abstraction and functionalization of small molecule substrate CH bonds. Inspired by this, if this efficient small molecule CH activation strategy can be extended to the melt processing system of polyolefin macromolecules, the synergistic catalytic system composed of TBN and N-hydroxyphthalimide (NHPI) is expected to achieve efficient graft modification of polyolefins under melt conditions. At the same time, the free radical capturing properties of NO can effectively suppress the main chain degradation side reactions at high temperatures. However, due to the high temperature, high viscosity, and complex reaction process of the melt system, the successful application of this catalytic system to the melt processing process faces many technical challenges, and no relevant technical solutions have been reported so far. Summary of the Invention

[0007] To address the shortcomings of existing post-functionalization modification technologies for polyolefins in the melt state, particularly those using peroxide-initiated systems, such as poor reaction selectivity, susceptibility to polyolefin backbone degradation or crosslinking at high temperatures, difficulty in controlling grafting uniformity, and large fluctuations in product quality, this invention aims to provide a novel post-functionalization modification method for polyolefins suitable for melt processing conditions and its application. This method utilizes the synergistic catalytic effect of tert-butyl nitrite and N-hydroxyphthalimide to achieve efficient and highly selective grafting modification of polyolefins under melt processing conditions, while effectively suppressing degradation side reactions and maintaining the excellent properties of the matrix material.

[0008] The purpose of this invention is to provide a method for preparing post-functionalized polyolefins using a melt-catalyzed co-catalytic process, characterized by the following preparation steps:

[0009] In melt processing equipment, a mixture including polyolefins, graft monomers, and catalysts is processed at the polyolefin melting temperature T. m The above grafting reaction is carried out, followed by extrusion and cooling to obtain the post-functionalized polyolefin.

[0010] The catalyst is selected from a combination of tert-butyl nitrite and N-hydroxyphthalimide.

[0011] In some embodiments of the present invention, the polyolefin is selected from at least one of low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), high-density polyethylene (HDPE), polypropylene (PP), polystyrene (PS), and polyolefin elastomer (POE).

[0012] In some embodiments of the present invention, the grafting monomer is selected from at least one of maleic anhydride, (meth)acrylic acid, (meth)acrylate, and ethylene. Examples of such grafting monomers include maleic anhydride (MAH), (meth)acrylic acid (AA / MAA), butyl (meth)acrylate (BA / MBA), methyl (meth)methacrylate (MA / MMA), polyoxyethylene (meth)acrylate, glycidyl (meth)acrylate (GA / GMA), styrene, and vinylsilanes (such as vinyltrimethoxysilane, vinyltriethoxysilane, etc.).

[0013] In some embodiments of the present invention, the mass ratio of the polyolefin to the grafted monomer is 100:1 to 15. Examples of such mass ratios include 100:1.5, 100:2, 100:2.5, 100:3, 100:3.5, 100:4, 100:4.5, 100:5, 100:6, 100:7, 100:8, 100:9, 100:10, 100:11, 100:12, 100:13, and 100:14.

[0014] In some embodiments of the present invention, the mass ratio of the polyolefin to the tert-butyl nitrite is 100:0.1 to 3. Examples of such mass ratios include 100:0.15, 100:0.2, 100:0.25, 100:0.3, 100:0.35, 100:0.4, 100:0.45, 100:0.5, 100:1, 100:1.5, 100:2, and 100:2.5.

[0015] In some embodiments of the present invention, the molar ratio of tert-butyl nitrite to N-hydroxyphthalimide is 1:0.1 to 5. Examples of such molar ratios include 1:0.5, 1:1, 1:1.5, 1:2, 1:2.5, 1:3, 1:3.5, 1:4, and 1:4.5.

[0016] In some embodiments of the invention, the melt processing equipment is selected from an internal mixer, a Hacker torque rheometer, a single-screw extruder, or a twin-screw extruder. A twin-screw extruder is preferred for continuous production.

[0017] In some embodiments of the present invention, the reaction temperature T of the grafting reaction satisfies T m +20℃≤T≤T m +60℃.

[0018] In some embodiments of the present invention, the grafting reaction time is 1 to 10 minutes. For example, when a continuous reaction is carried out using an extruder, the residence time in the extruder screw is 1 to 10 minutes. Furthermore, the screw speed is 50 rpm to 300 rpm at this time.

[0019] In some embodiments of the present invention, the tert-butyl nitrite is added to the melt processing equipment in at least one of the following forms:

[0020] a. In the form of pre-complexation or adsorption of tert-butyl nitrite with N-hydroxyphthalimide;

[0021] b. Tert-butyl nitrite pre-adsorbed onto an inorganic carrier;

[0022] c. Tert-butyl nitrite dissolved in a small amount of high-boiling-point additives;

[0023] d. At the melting temperature T of polyolefins m The above method involves directly injecting tert-butyl nitrite using a liquid injection system.

[0024] The above-mentioned form is mainly due to the low boiling point of tert-butyl nitrite, and is intended to prevent or reduce the volatilization loss of tert-butyl nitrite during processing.

[0025] For form a above, the pre-complexation or adsorption step of tert-butyl nitrite with N-hydroxyphthalimide can be carried out at -5 to 8°C. Furthermore, this step can be carried out in a closed container for 10 to 60 minutes.

[0026] For form b above, the inorganic carrier is a common type, such as silica or carbon materials. Furthermore, the adsorption can be carried out at -5 to 8°C. Further, this step can be performed in a closed container for 10 to 60 minutes.

[0027] For form c above, the high-boiling-point additive is selected from at least one of liquid paraffin, dioctyl phthalate, and mineral oil. Furthermore, the term "small amount of high-boiling-point additive" refers to an amount sufficient to dissolve tert-butyl nitrite. Additionally, the dissolution step can be carried out at -5 to 8°C.

[0028] For form d above, for example, when the melt processing equipment is an extruder, a liquid injection system can be used to directly inject TBN into the melting section of the extruder.

[0029] In some embodiments of the present invention, the grafting rate of the post-functionalized polyolefin is 0.4 to 2.0 mol%, for example, the grafting rate is 0.5, 0.6, 0.7, 0.8, 1.0, 1.2, 1.5, or 1.8 mol%.

[0030] In some embodiments of the present invention, the rate of change of the melt index of the post-functionalized polyolefin relative to the melt index of the polyolefin is less than 40%, preferably less than 20%, or even less than 10%.

[0031] In some embodiments of the present invention, the gel content in the post-functionalized polyolefin is less than 0.1%.

[0032] In some embodiments of the present invention, the obtained post-functionalized polyolefin can be further purified. For example, by drying the obtained post-functionalized polyolefin in a vacuum drying oven (60~80°C), or by dissolving the obtained post-functionalized polyolefin and then precipitating it.

[0033] Another object of the present invention is to provide post-functionalized polyolefins obtained by the above method for use as polymer compatibilizers, compatibilizers, adhesion promoters, interface modifiers, coating materials or adhesive layer materials.

[0034] In some embodiments of the present invention, the post-functionalized polyolefin serves as a compatibilizer or enhancer in a blend of polyolefin and polar polymer, or as a compatibilizer or enhancer in a blend of polyolefin and inorganic / organic fillers (such as wood-plastic composites).

[0035] In some embodiments of the present invention, the post-functionalized polyolefin is used as an adhesion promoter in polyolefin composite materials, or as an adhesion promoter for polyolefin composite materials combined with other materials.

[0036] In some embodiments of the present invention, the post-functionalized polyolefin serves as an interface modifier for the surface of a polyolefin or a polyolefin composite material.

[0037] In some embodiments of the present invention, the post-functionalized polyolefin is used as a coating material for polyolefins or polyolefin composites, that is, the coating material includes the post-functionalized polyolefin.

[0038] In some embodiments of the present invention, the post-functionalized polyolefin is used as an adhesive layer material between the metal and the polyolefin composite material; that is, the adhesive layer material includes the post-functionalized polyolefin.

[0039] Compared with the prior art, the present invention has the following beneficial effects:

[0040] This invention is the first to introduce a TBN / NHPI synergistic catalytic system into the solution-phase post-functionalization modification of polyolefin macromolecules. This system utilizes the tert-butoxy radical generated by the thermal decomposition of TBN under mild conditions to selectively extract hydroxyl hydrogen from NHPI, generating highly reactive phthalimide-N-oxygen radicals (PINO•), thereby achieving selective activation and grafting of the CH bonds in the polyolefin molecular chain. This mechanism avoids the random attack on the polyolefin backbone by traditional radical initiators, significantly improving the selectivity of the reaction.

[0041] Nitric oxide (NO) produced by TBN decomposition is a stable free radical scavenger. In high-temperature molten systems, it can promptly capture any potential free radicals in polyolefin macromolecules, forming relatively stable intermediates. This effectively inhibits the thermal oxidative degradation and β-fracture reactions that are difficult to avoid in traditional melt grafting processes. Gel permeation chromatography (GPC) and melt index (MFI) tests show that the molecular weight and melt index of the polyolefin change very little before and after modification, and the mechanical and processing properties of the material are preserved to the greatest extent, essentially eliminating the gelation phenomenon.

[0042] This invention's method can be directly implemented in existing polymer melt processing equipment (especially twin-screw extruders) without requiring large-scale modifications to the production line. The process is simple, with a wide operating window, enabling stable continuous production and demonstrating excellent prospects for industrial application. The melt method itself eliminates the need for solvents, avoiding the solvent recovery and environmental pressures associated with solution methods. Tert-butyl nitrite and its byproducts (tert-butanol, nitrogen) are environmentally friendly. Furthermore, this catalytic system is not only suitable for various polyolefin substrates but can also flexibly introduce various polar functional groups such as carboxyl, anhydride, epoxy, hydroxyl, and silane groups by changing different functional monomers. The prepared functionalized polyolefins can be used as polymer compatibilizers, compatibilizers, adhesive layer materials, coating materials, and interface modifiers for various high-performance polyolefin alloys, showing broad application prospects in automotive materials, packaging materials, and electronics. Detailed Implementation

[0043] To enable those skilled in the art to better understand the technical solutions of this invention, the technical solutions of this invention will be clearly and completely described below in conjunction with the embodiments of this invention. Obviously, the described embodiments are only some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of this invention.

[0044] Unless otherwise specified, all materials and reagents used are commercially available.

[0045] In the following examples and comparative examples:

[0046] Melt Flow Index (MFI): Tested using a German Zwick / Roell 4106 melt flow indexer according to GB / T 3682-2018 standard. The test conditions for polypropylene were 230℃ / 2.16kg, and the test conditions for polyethylene were 190℃ / 2.16kg.

[0047] Grafting rate of functionalized polyolefins: For maleic anhydride grafted products, the grafting rate was determined by alkaline titration. Specifically, the purified product was dissolved in hot xylene and titrated with KOH-ethanol standard solution to calculate the anhydride content. For acrylic acid grafted products, the carboxyl content was determined by acid-base titration.

[0048] Number-average molecular weight (Mn), weight-average molecular weight (Mw), and molecular weight distribution (PDI) of functionalized polyolefins were determined using high-temperature gel permeation chromatography (HT-GPC) with 1,2,4-trichlorobenzene (TCB) as the eluent at a flow rate of 1.0 ml / min and a test temperature of 150 °C.

[0049] Melting point of functionalized polyolefin: determined by differential scanning calorimetry (DSC). The DSC curve is recorded as the second heating curve from 30 °C to 200 °C, with a heating rate of 10 °C / min and a cooling rate of 10 °C / min.

[0050] Example 1

[0051] This embodiment provides a maleic anhydride-grafted modified polypropylene (PP-g-MAH), the synthesis method of which is as follows:

[0052] Take polypropylene (M) n =59.1 kg / mol, PDI=5.21, T m=164.5℃, melt index MFI 3.2 g / 10min) 1000g, N-hydroxyphthalimide (NHPI) 5.0g (30.6mmol), tert-butyl nitrite (TBN) 3.2g (31.0mmol), maleic anhydride (MAH) 30g. NHPI and TBN were premixed in a sealed container at 0℃ for 30 minutes to allow TBN to fully adsorb onto the NHPI surface. The premixed material was then mixed with PP and MAH in a high-speed mixer for 3 minutes. The mixture was added to a twin-screw extruder (L / D ratio L / D = 40, screw diameter 35mm). The extruder temperatures were set as follows: feeding section 160℃, conveying section 180℃, reaction section 190℃, metering section 190℃, die head 190℃. The screw speed was 150rpm, the feed rate was 10kg / h, and the residence time was approximately 2.5±0.5min. The extruded strip was water-cooled and granulated, and the resulting product was vacuum-dried at 80℃ for 12 hours to obtain PP-g-MAH. The maleic anhydride grafting rate was calculated to be 1.12 mol% based on titration results; M n =58.2Kg / mol, PDI=5.36; T m =164.2℃; MFI=3.5 g / 10min.

[0053] Example 2

[0054] This embodiment provides a maleic anhydride-modified linear low-density polyethylene (LLDPE-g-MAH), the synthesis method of which is as follows:

[0055] Take linear low-density polyethylene (M n =33.1 kg / mol, PDI=3.31, T m =125.1℃, MFI 2.0 g / 10min) 1000g, NHPI 8.0g (49.0mmol), TBN 5.0g (48.5mmol), maleic anhydride 40g. NHPI and TBN were premixed and fully adsorbed as in Example 1, and then mixed with LDPE and MAH in a high-speed mixer for 5 minutes. The mixture was added to a twin-screw extruder with the following temperature settings: feeding section 140℃, conveying section 160℃, reaction section 180℃, metering section 180℃, and die head 180℃. The screw speed was 120rpm, the feeding rate was 8kg / h, and the residence time was approximately 3-4 minutes. Nitrogen gas was introduced for protection. Post-treatment was the same as in Example 1. The maleic anhydride grafting rate was calculated to be 1.35 mol% by titration; M n =32.5Kg / mol, PDI=3.31; T m =124.8℃; MFI=2.1 g / 10min.

[0056] Example 3

[0057] This embodiment provides a grafted maleic anhydride modified high-density polyethylene (HDPE-g-MAH), the synthesis method of which is as follows:

[0058] Take high-density polyethylene (M n =18.5Kg / mol, PDI=8.38, T m =132.8℃, MFI 0.9 g / 10min) 1000g, NHPI 6.0g (36.8mmol), TBN 3.8g (36.8mmol), maleic anhydride 35g. NHPI and TBN were premixed and fully adsorbed as in Example 1, and then mixed with HDPE and MAH in a high-speed mixer for 5 minutes. The mixture was then added to a twin-screw extruder. The extruder temperatures were set as follows: feeding section 150℃, conveying section 170℃, reaction section 190℃, metering section 190℃, and die head 190℃. The screw speed was 100 rpm, the feed rate was 8 kg / h, and the residence time was approximately 4 minutes. Post-treatment was the same as in Example 1. The maleic anhydride grafting rate was calculated to be 1.08 mol% by titration; M n =18.2Kg / mol, PDI=8.41; T m =132.5℃; MFI=0.9g / 10min.

[0059] Example 4

[0060] This embodiment provides a method for synthesizing glycidyl methacrylate-grafted modified polypropylene (PP-g-GMA) as follows:

[0061] Take PP (M) n =59.1 kg / mol, PDI=5.21, T m =164.5℃, MFI 3.2 g / 10min 1000g, NHPI 4.0g (24.5mmol), TBN 2.5g (24.2mmol), glycidyl methacrylate (GMA) 25g. NHPI and TBN were premixed and fully adsorbed as in Example 1, and then mixed with PP and GMA in a high-speed mixer for 5 minutes. The mixture was then fed into a twin-screw extruder. The extruder temperatures were set as follows: feeding section 160℃, conveying section 180℃, reaction section 190℃, metering section 190℃, and die head 190℃. The screw speed was 150rpm, the feed rate was 10kg / h, and the post-treatment was the same as in Example 1. The grafting rate was determined to be 0.86 mol% by epoxy titration; M n =57.8 kg / mol, PDI=5.35; T m =164.0℃; MFI=3.4 g / 10min.

[0062] Example 5

[0063] This embodiment provides a grafted acrylic acid modified high-density polyethylene (PP-g-AA), the synthesis method of which is as follows:

[0064] Take PP (M) n =59.1 kg / mol, PDI=5.21, T m =164.5℃, MFI 3.2 g / 10min) 1000g, NHPI 6.0g (36.8mmol), TBN 3.8g (36.8mmol), acrylic acid (AA) 20g. NHPI and TBN were premixed and fully adsorbed according to Example 1, and then mixed with PP and AA in a high-speed mixer for 5 minutes. The mixture was added to a twin-screw extruder, and the extruder temperature was set as follows: feeding section 150℃, conveying section 170℃, reaction section 180℃, metering section 180℃, and die head 180℃. The screw speed was 120 rpm, the feeding rate was 8 kg / h, the extruded strip was water-cooled and granulated, and the resulting product was vacuum dried at 60℃ for 12 hours. The grafting rate was determined to be 0.75 mol% by acid-base titration; M n =55.2 kg / mol, PDI=5.40; T m =163.5℃; MFI=3.9 g / 10min.

[0065] Example 6

[0066] This embodiment explores the effect of different MAH dosages on grafting effects.

[0067] Using 1000g of fixed PP (same as in Example 1), 5.0g of NHPI, and 3.2g of TBN, and under the same reaction conditions as in Example 1, but with varying MAH dosage, a series of PP-g-MAH samples 6-1 to 6-4 were prepared. Their grafting rate and M... n PDI and MFI are shown in Table 1.

[0068] Table 1: Properties of PP-g-MAH obtained with different MAH dosages

[0069]

[0070] Comparative Example 1: This comparative example explores the differences between the TBN / NHPI system and the traditional peroxide DCP system.

[0071] Using the same PP base material and MAH dosage (same as in Example 1), melt grafting was compared using the TBN / NHPI system of this invention (same as in Example 1) and the traditional dicumyl peroxide (DCP) initiation system. The DCP system formulation was: 1000g PP, 1.5g DCP, 30g MAH; reaction conditions: temperature 180℃, other conditions the same as in Example 1. The results are shown in Table 2.

[0072] Table 2: Properties of PP-g-MAH obtained from different initiation systems

[0073]

[0074] As shown in Table 2, compared with the traditional DCP system, the TBN / NHPI system of this invention has a higher grafting rate, while effectively maintaining the molecular weight and thermal properties of polypropylene, with extremely low degradation, small change in melt index, and no gel formation (gel content was measured by the dissolution method). Its overall performance is significantly better than that of the traditional peroxide initiation system.

[0075] Comparative Example 2: NHPI replaced by other free radical scavengers

[0076] NHPI was replaced with equimolar amounts of 2,2,6,6-tetramethylpiperidine oxide (TEMPO, Comparative Example 2-1) and 2,6-di-tert-butyl-4-methylphenol (BHT, Comparative Example 2-2), respectively, under the same conditions as in Example 1. The properties of the resulting PP-g-MAH are shown in Table 3.

[0077] Table 3: Properties of PP-g-MAH obtained with different free radical scavengers

[0078]

[0079] As shown in Table 3, TEMPO and BHT, acting as free radical scavengers, quench free radicals in the system, inhibiting the grafting reaction and failing to exert a catalytic effect similar to NHPI, resulting in a very low grafting rate. This indicates that the unique structure of NHPI is key to its catalytic function.

[0080] Application Example 1: Application of post-functionalized polyolefins as compatibilizers in PP / PA6 alloys

[0081] The PP-g-MAH (grafting rate 1.12%) prepared in Example 1 was used as a compatibilizer and blended with PP and PA6 in a twin-screw extruder in the following ratio: 70 parts PP, 30 parts PA6, and 10 parts PP-g-MAH. Extrusion temperature: 220℃, screw speed: 200 rpm.

[0082] Meanwhile, a simple PP / PA6 (70 / 30) blend without compatibilizer, or a PP / PA6 blend with commercially available MAH-g-PP (Shenghao's PP-g-MAH, grafting rate of approximately 0.9%) added according to the above dosage, was used as a control sample.

[0083] The mechanical properties and morphological structure of the above blends were tested, and the results are shown in Table 4.

[0084] Table 4: Properties of different PP / PA6 alloys

[0085]

[0086] Application Example 2: Application of Post-functionalized Polyolefins in Wood-Plastic Composites

[0087] The HDPE-g-MAH prepared in Example 3 was used as a compatibilizer and blended with HDPE and wood flour in a twin-screw extruder in the following proportions: 60 parts HDPE, 40 parts wood flour, and 5 parts HDPE-g-MAH. The extrusion temperature was 170°C, and the screw speed was 150 rpm. Standard specimens were injection molded, and their mechanical properties were tested.

[0088] Meanwhile, wood-plastic composite materials without compatibilizers, or wood-plastic composite materials with commercially available compatibilizers (Shenghao's HDPE-g-MAH, with a grafting rate of approximately 1.2%) added according to the above dosage, were used as comparative samples.

[0089] The above samples were injection molded into standard specimens, and their mechanical properties were tested. The results are shown in Table 5.

[0090] Table 5: Properties of different wood-plastic composite materials

[0091]

[0092] Application Example 3: Application of Post-functionalized Polyolefins in the Adhesive Layer of Aluminum-Plastic Composite Pipes

[0093] The LLDPE-g-MAH prepared in Example 2 was blended with LLDPE in a 1:3 ratio, and a 50 μm thick film was prepared on a small casting film machine as an adhesive layer. The film was placed between an aluminum plate and a PE plate and hot-pressed at 180°C and 0.5 MPa for 5 minutes to prepare an aluminum / PE composite board.

[0094] Meanwhile, an adhesive layer without LLDPE-g-MAH, or with commercially available LLDPE-g-MAH (Shenghao's LLDPE-g-MAH, with a grafting rate of approximately 0.9%) added according to the above dosage, was used as a control sample.

[0095] The peel strength of the aluminum / PE composite sheet was tested (180° peel, speed 50 mm / min), and the results are shown in Table 6.

[0096] Table 6: Performance of Different Aluminum / PE Composite Sheets

[0097]

[0098] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that after reading this application specification, they can still modify or make equivalent substitutions to the specific implementation of the present invention, but these modifications or changes do not depart from the protection scope of the pending claims of the present invention.

Claims

1. A method for preparing post-functionalized polyolefins via melt-catalysis, characterized in that, The preparation steps include the following: In melt processing equipment, a mixture including polyolefins, graft monomers, and catalysts is processed at the polyolefin melting temperature T. m The above grafting reaction is carried out, followed by extrusion and cooling to obtain the post-functionalized polyolefin. The catalyst is selected from a combination of tert-butyl nitrite and N-hydroxyphthalimide.

2. The method according to claim 1, characterized in that, The polyolefin is selected from at least one of low-density polyethylene, linear low-density polyethylene, high-density polyethylene, polypropylene, polystyrene, and polyolefin elastomers; And / or, the grafting monomer is selected from at least one of maleic anhydride, (meth)acrylic acid, (meth)acrylate, and ethylene. And / or, the mass ratio of the polyolefin to the grafted monomer is 100:1~15.

3. The method according to claim 1, characterized in that, The mass ratio of the polyolefin to the tert-butyl nitrite is 100:0.1~3; And / or, the molar ratio of the tert-butyl nitrite to the N-hydroxyphthalimide is 1:0.1~5.

4. The method according to claim 1, characterized in that, The melt processing equipment is selected from internal mixers, Hacker torque rheometers, single-screw extruders, or twin-screw extruders.

5. The method according to claim 1, characterized in that, The reaction temperature T of the grafting reaction satisfies T m +20℃≤T≤T m +60℃; and / or, the reaction time of the grafting reaction is 1~10 min.

6. The method according to claim 1, characterized in that, The tert-butyl nitrite is added to the melt processing equipment in at least one of the following forms: a. In the form of pre-complexed or adsorbed tert-butyl nitrite with N-hydroxyphthalimide; b. Tert-butyl nitrite pre-adsorbed onto an inorganic carrier; c. Tert-butyl nitrite dissolved in a small amount of high-boiling-point additives; d. At the melting temperature T of polyolefins m The above method involves directly injecting tert-butyl nitrite using a liquid injection system.

7. The method according to claim 1, characterized in that, The grafting rate of the post-functionalized polyolefin is 0.4~2.0 mol% And / or, the melt index of the post-functionalized polyolefin changes by a rate of less than 40% relative to the melt index of the polyolefin.

8. The post-functionalized polyolefin obtained by the method according to any one of claims 1 to 7, and its application as a polymer compatibilizer, compatibilizer, adhesion promoter, interface modifier, coating material or adhesive layer material.

9. The application according to claim 8, characterized in that, The post-functionalized polyolefin serves as a compatibilizer or solubilizer in the blending system of polyolefin and polar polymer. Alternatively, the post-functionalized polyolefin can be used as a compatibilizer or compatibilizer in a blend system of polyolefin and inorganic / organic fillers.

10. The application according to claim 8, characterized in that, The post-functionalized polyolefin serves as an adhesive layer material between the metal and the polyolefin composite material.

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