Compatilizer for improving surface performance and interface cohesiveness of polyolefin elastomer

Abstract

The invention discloses a compatilizer for improving surface performance and interface cohesiveness of a polyolefin elastomer, which is prepared by the following steps: pre-swelling a polyolefin elastomer matrix and a polar monomer protected by silane in a supercritical CO2 environment, and adding an amphiphilic block copolymer to form a microphase separation structure; controllable free radical grafting is implemented through a double-screw extruder under the conditions that the temperature is 160-220 DEG C and the shearing rate is 100-500 s <-1 >, the particle size D50 of a final product is controlled to be 50-300 microns, and the surface energy is increased to 35-55 mN / m. A polyolefin elastomer matrix and a polar monomer protected by silane are pre-swelled in a supercritical CO2 environment, an amphiphilic block copolymer is added to form a micro-phase separation structure, the polar monomer (MAH) permeates into a polyolefin amorphous region through supercritical CO2 pre-swelling, the silane protection monomer inhibits side reaction, and a contact angle method is utilized to prepare the super-hydrophobic polyolefin elastomer. And the accurate control of the grafting layer thickness can be effectively improved.

Description

Technical Field

[0001] The present invention relates to the technical field of polyolefin materials, and specifically relates to a compatibilizer for improving the surface properties and interfacial adhesion of polyolefin elastomers. Background Art

[0002] Polyolefin elastomers (such as POE, EPDM) are widely used in fields such as automotive, electronics, and packaging due to their excellent flexibility and processability. However, their non-polar surface characteristics result in insufficient interfacial adhesion strength with polar materials (such as nylon, EVOH, metal) (usually the peel strength < 20 N / cm), severely restricting the comprehensive performance of composite materials. In the prior art, maleic anhydride (MAH) graft modification is often used to improve interfacial compatibility, but there are the following technical bottlenecks: in the traditional melt grafting process, the diffusion of polar monomers in the polyolefin matrix is limited and unevenly distributed, resulting in limited interfacial enhancement effect, and the decomposition temperature of the free radical initiator has a poor match with the polyolefin processing temperature, and matrix degradation is easily caused at high temperatures; therefore, there is an urgent need to design a compatibilizer for improving the surface properties and interfacial adhesion of polyolefin elastomers to solve the above problems. Summary of the Invention

[0003] The purpose of the present invention is to provide a compatibilizer for improving the surface properties and interfacial adhesion of polyolefin elastomers to solve the above deficiencies in the prior art.

[0004] To achieve the above purpose, the present invention provides the following technical solution: A compatibilizer for improving the surface properties and interfacial adhesion of polyolefin elastomers is prepared by melt grafting reaction from the following raw materials in parts by mass: 100 parts of polyolefin elastomer matrix; 5 - 30 parts of polar monomer graft; 3 - 20 parts of amphiphilic block copolymer; 0.1 - 5 parts of free radical initiator; 1 - 10 parts of interfacial enhancer; The compatibilizer satisfies the interfacial adhesion strength enhancement function; as shown in the appendix Figure 1 Shown, in the formula: σinterface is the interfacial shear strength (MPa); σmatrix is the matrix tensile strength (MPa); Ggraft is the grafting rate (%); Dpolar is the polar monomer distribution density (mol / m³); Tm is the melting point of polyolefin (°C); Tproc is the processing temperature (°C); α is the structure factor (0.5 ≤ α ≤ 2.0); The preparation method includes: pre-swelling a polyolefin elastomer matrix and a polar monomer protected by silane in a supercritical CO2 environment, adding an amphiphilic block copolymer to form a microphase separation structure, and performing controlled radical grafting by a twin-screw extruder at 160 - 220 °C and a shear rate of 100 - 500 s -1 under the conditions, and controlling the D50 of the final product particle size to be 50 - 300 μm and the surface energy to be increased to 35 - 55 mN / m.

[0005] Preferably, the polyolefin elastomer matrix is selected from ethylene-octene copolymer, ethylene-propylene copolymer or propylene-based elastomer, with a melt index of 0.5 - 20 g / 10min and a density of 0.86 - 0.91 g / cm 3 , where the octene monomer content is 8 - 15 wt%, and it is an elastomer with a narrow molecular weight distribution (PDI ≤ 3.0) prepared by a metallocene catalyst.

[0006] Preferably, the polar monomer graft is a composite system of glycidyl methacrylate protected by trimethylsilane and maleic anhydride, with a molar ratio of 1:0.5 - 2.0, the grafting rate is controlled at 1.2 - 3.8% by in-line infrared spectroscopy, and the graft layer thickness is measured to be 5 - 20 nm by atomic force microscopy.

[0007] Preferably, the amphiphilic block copolymer is polystyrene-b-polymethyl methacrylate or polyethylene-b-polyethylene oxide, with a molecular weight of 50,000 - 500,000 g / mol, where the hydrophilic segment accounts for 15 - 40%, and the period size of the microphase separation structure measured by small-angle X-ray scattering is 10 - 50 nm.

[0008] Preferably, the radical initiator is a compound system of dicumyl peroxide (DCP) and 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane, with a compound ratio of 1:0.5 - 1.5, the difference between the half-life temperature and the processing temperature is controlled within ±5 °C, and the decomposition activation energy is measured to be 120 - 150 kJ / mol by the Kissinger method.

[0009] Preferably, the interface enhancer is a composite of nano-scale silica aerogel and ionic liquid, where the SiO2 particle size is 10 - 50 nm, the specific surface area is 500 - 800 m 2 / g, the ionic liquid is 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, and the loading amount of the nano-scale silica aerogel is controlled at 15 - 30 wt% by the impregnation method.

[0010] Preferably, in the pre-swelling stage, supercritical CO2 with a pressure of 8 - 15 MPa, a temperature of 80 - 120 °C, and a swelling time of 30 - 120 min is used. The degree of swelling is measured by the gravimetric method to be 20 - 50%, and immediately after swelling, quenching treatment is carried out to make the polar monomer orientedly distributed in the amorphous region of the elastomer.

[0011] Preferably, the ratio of the length to the diameter of the twin-screw extruder L / D ≥ 40, and it is configured with a combination of reverse kneading blocks and pin mixing elements. The melt residence time is synergistically controlled at 2 - 5 min by the screw speed (100 - 300 rpm) and the feeding rate (5 - 20 kg / h), and the grafting reaction conversion rate is monitored by on-line Raman spectroscopy ≥ 85%.

[0012] Preferably, the storage modulus G' of the final product is 1×10 - 5×10 4 Pa at 190 °C, the peak temperature of the loss factor tanδ is increased by 10 - 25 °C compared with the matrix, and the interfacial diffusion coefficient measured by neutron reflection method is 1×10 -16 ~5×10 -15 m 2 / s.

[0013] Preferably, when applied to automotive sealing strips, the peel strength from the polypropylene matrix ≥ 35 N / cm, the retention rate of heat aging resistance (150 °C × 1000 h) ≥ 80%, and the interfacial toughness at -40 °C low temperature is measured by the notch impact test ≥ 45 kJ / m².

[0014] In the above technical solution, a compatibilizer for improving the surface performance and interfacial adhesion of polyolefin elastomers provided by the present invention: (1) adopts pre-swelling of the polyolefin elastomer matrix and a polar monomer protected by silane in a supercritical CO2 environment, adding an amphiphilic block copolymer to form a microphase separation structure. Supercritical CO2 pre-swelling enables the polar monomer (MAH) to penetrate into the amorphous region of the polyolefin, and the silane-protected monomer inhibits side reactions. By using the contact angle method, the thickness of the grafted layer can be effectively improved and precisely controlled; (2) adopts a compound initiating system of DCP and di-tert-butyl peroxide, adjusts the temperature difference between the half-life temperature and the processing temperature, and the grafting conversion rate can be effectively improved in cooperation with the high shear field of the twin-screw extruder, avoiding thermal degradation of the matrix. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings required in the embodiments. Obviously, the drawings described below are only some embodiments recorded in the present invention. For those of ordinary skill in the art, other drawings can also be obtained according to these drawings.

[0016] Figure 1Schematic diagram of the calculation function provided for an example of a compatibilizer for improving the surface properties and interfacial adhesion of polyolefin elastomers according to the present invention. Detailed implementation mode

[0017] In order to enable those skilled in the art to better understand the technical solutions of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings.

[0018] As Figure 1 shown, a compatibilizer for improving the surface properties and interfacial adhesion of polyolefin elastomers provided by an embodiment of the present invention is prepared by melt grafting reaction from the following raw materials in parts by mass: 100 parts of polyolefin elastomer matrix; 5 - 30 parts of polar monomer graft; 3 - 20 parts of amphiphilic block copolymer; 0.1 - 5 parts of free radical initiator; 1 - 10 parts of interfacial enhancer; The compatibilizer satisfies the interfacial adhesion strength improvement function; as shown in the appendix Figure 1 shown, in the formula: σinterface is the interfacial shear strength (MPa); σmatrix is the matrix tensile strength (MPa); Ggraft is the grafting rate (%); Dpolar is the polar monomer distribution density (mol / m³); Tm is the melting point of polyolefin (°C); Tproc is the processing temperature (°C); α is the structure factor (0.5 ≤ α ≤ 2.0); Its preparation method includes: pre - swelling the polyolefin elastomer matrix and the polar monomer protected by silane in a supercritical CO2 environment, adding an amphiphilic block copolymer to form a microphase separation structure, and performing controlled radical grafting through a twin - screw extruder at 160 - 220 °C and a shear rate of 100 - 500 s -1 conditions, and controlling the D50 of the final product particle size to be 50 - 300 μm, and the surface energy is increased to 35 - 55 mN / m.

[0019] Preferably, the polyolefin elastomer matrix is selected from ethylene - octene copolymer (POE), ethylene - propylene copolymer (EPDM) or propylene - based elastomer (OBCs), its melt index is 0.5 - 20 g / 10min, and the density is 0.86 - 0.91 g / cm 3 , where the octene monomer content is 8 - 15 wt%, and it is an elastomer with a narrow molecular weight distribution (PDI ≤ 3.0) prepared by a metallocene catalyst.

[0020] Preferably, the polar monomer graft is a composite system of glycidyl methacrylate protected by trimethylsilane (GMA-Si) and maleic anhydride (MAH), with a molar ratio of 1:0.5 - 2.0 between the two. The grafting rate is controlled at 1.2 - 3.8% by on-line infrared spectroscopy, and the thickness of the graft layer is measured to be 5 - 20 nm by atomic force microscopy.

[0021] Preferably, the amphiphilic block copolymer is polystyrene-b-polymethyl methacrylate (PS-b-PMMA) or polyethylene-b-polyethylene oxide (PE-b-PEO), with a molecular weight of 50,000 - 500,000 g / mol, where the hydrophilic segment accounts for 15 - 40%. The period size of the microphase separation structure is measured to be 10 - 50 nm by small-angle X-ray scattering (SAXS).

[0022] Preferably, the free radical initiator is a compounding system of dicumyl peroxide (DCP) and 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane, with a compounding ratio of 1:0.5 - 1.5. The difference between the half-life temperature and the processing temperature is controlled within ±5 °C, and the decomposition activation energy is measured to be 120 - 150 kJ / mol by the Kissinger method.

[0023] Preferably, the interfacial enhancer is a composite of nano-scale silica aerogel and ionic liquid, where the particle size of SiO2 is 10 - 50 nm, the specific surface area is 500 - 800 m 2 / g, the ionic liquid is 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([BMIM][TFSI]), and the loading amount is controlled at 15 - 30 wt% by the impregnation method.

[0024] Preferably, in the pre-swelling stage, supercritical CO2 with a pressure of 8 - 15 MPa and a temperature of 80 - 120 °C is used, the swelling time is 30 - 120 min, the swelling degree is measured to be 20 - 50% by the gravimetric method, and immediately after swelling, a quenching treatment is carried out to make the polar monomer oriented in the amorphous region of the elastomer.

[0025] Preferably, the length-to-diameter ratio L / D of the twin-screw extruder is ≥40, and it is equipped with a combination of reverse engagement blocks and pin mixing elements. The melt residence time is synergistically controlled at 2 - 5 min by the screw speed (100 - 300 rpm) and the feeding rate (5 - 20 kg / h), and the conversion rate of the grafting reaction is monitored by on-line Raman spectroscopy ≥85%.

[0026] Preferably, the storage modulus G' of the final product is 1×10~5×10 4 Pa at 190 °C, the peak temperature of the loss factor tanδ is increased by 10 - 25 °C compared with the matrix, and the interfacial diffusion coefficient is measured to be 1×10 -16 ~5×10 -15 m 2 / s.

[0027] Preferably, when applied to automotive sealing strips, the peel strength from the polypropylene matrix is ≥ 35 N / cm, the retention rate of heat aging resistance (150 °C × 1000 h) is ≥ 80%, and the interfacial toughness at -40 °C is ≥ 45 kJ / m as determined by the notched impact test. 2 .

[0028] Example 1 The raw materials in parts by mass are prepared through melt grafting reaction. POE matrix (Dow Engage 8842, melt index 5 g / 10 min, octene content 12 wt%): 100 MAH-Si (maleic anhydride protected by silane, purity 99.5%): 18 PS-b-PMMA (molecular weight 280,000, hydrophilic segment ratio 30%): 10 DCP / di-tert-butyl peroxide (1:1 compound): 0.8 SiO2 aerogel (particle size 20 nm, specific surface area 650 m 2 / g): 5 During the melt grafting reaction Pre-swelling: POE is treated in supercritical CO2 (12 MPa, 100 °C) for 60 min, and the swelling degree is 35%; Grafting reaction: In a twin-screw extruder (L / D = 48, length-diameter ratio), the temperature gradient is (180 °C / 200 °C / 210 °C / 195 °C), the screw speed is 250 rpm, and the shear rate is 300 s -1 ; Post-treatment: Water cooling and pelletizing, particle size D50 = 120 μm.

[0029] Test results Index Result Testing method Grafting ratio 1.8% Acid-base titration method Surface energy 42 mN / m Owens-Wendt equation Interfacial shear strength (PP / PA66) 38 MPa ASTM D3164 Peeling strength (after aging at 150°C) 32 N / cm (retention rate 82%) ASTM D1876 Melt flow index fluctuation ±3.2% ISO 1133 Example 2 The raw materials in parts by mass are prepared through melt grafting reaction: POE matrix: ExxonMobil Vistamaxx 6202 (propylene-based OBCs, melt index 15 g / 10 min) Polar monomer: MAH-Si and GMA-Si (molar ratio 1:1) Amphiphilic copolymer: PE-b-PEO (molecular weight 150,000, hydrophilic segment ratio 25%) Initiator: DCP / di-tert-butyl peroxide (1:0.8) SiO2 supported ionic liquid ([BMIM][TFSI], loading amount 25 wt%) During the melt grafting reaction The supercritical CO2 pressure is increased to 14 MPa, and the swelling time is 90 min (the swelling degree is 45%) The peak extrusion temperature is 220 °C, and the screw speed is 180 rpm (shear rate 200 s -1 ) Test results Index Result Grafting ratio (total polar groups) 2.5% Peeling strength (PP / EVOH) 47 N / cm Moisture and heat resistance (85°C / 85%RH×30 days) Impact strength retention rate 92% Filler dispersion degree (AFM) Agglomerate size ≤50nm In the above examples, the raw materials of grafted reaction SiO2 aerogel (particle size 20 nm, specific surface area 650 m 2 / g): 5 are different from those of SiO2-supported ionic liquid ([BMIM][TFSI], loading amount 25 wt%). The gradient experiments verify the feasibility of all numerical ranges in the claims and prove the stability of the present invention in industrial production.

[0030] Only some exemplary embodiments of the present invention are described above by way of illustration. Undoubtedly, for those of ordinary skill in the art, the described embodiments can be modified in various different ways without departing from the spirit and scope of the present invention. Therefore, the above drawings and descriptions are illustrative in nature and should not be construed as limiting the scope of protection of the claims of the present invention.

Claims

1. A compatibilizer for improving the surface properties and interfacial adhesion of polyolefin elastomers, characterized in that, It is prepared by a melt grafting reaction from the following raw materials in parts by mass: 100 parts of a polyolefin elastomer matrix; 5 - 30 parts of a polar monomer graft; 3 - 20 parts of an amphiphilic block copolymer; 0.1 - 5 parts of a radical initiator; 1 - 10 parts of an interfacial enhancer; The compatibilizer satisfies the interfacial adhesion strength enhancement function: ； In the formula: σinterface is the interfacial shear strength (MPa); σmatrix is the matrix tensile strength (MPa); Ggraft is the grafting rate (%); Dpolar is the polar monomer distribution density (mol / m³); Tm is the melting point of the polyolefin (°C); Tproc is the processing temperature (°C); α is the structure factor (0.5 ≤ α ≤ 2.0); The preparation method includes: pre-swelling a polyolefin elastomer matrix and a polar monomer protected by silane in a supercritical CO2 environment, adding an amphiphilic block copolymer to form a microphase separation structure, and performing controlled radical grafting by a twin-screw extruder at 160-220 °C and a shear rate of 100-500 s -1 conditions, and controlling the D50 of the final product to be 50-300 μm and the surface energy to be increased to 35-55 mN / m.

2. The compatibilizer for improving the surface properties and interfacial adhesion of polyolefin elastomer according to claim 1, characterized in that The polyolefin elastomer matrix is selected from ethylene-octene copolymers, ethylene-propylene copolymers or propylene-based elastomers, having a melt index of 0.5-20 g / 10min and a density of 0.86-0.91 g / cm 3 , wherein the octene monomer content is 8-15 wt%, and is a narrow molecular weight distribution (PDI≤3.0) elastomer prepared by a metallocene catalyst.

3. The compatibilizer for improving the surface properties and interfacial adhesion of polyolefin elastomer according to claim 1, characterized in that, The polar monomer graft is a composite system of glycidyl methacrylate protected by trimethylsilane and maleic anhydride, with a molar ratio of 1:0.5 - 2.

0. The grafting rate is controlled at 1.2 - 3.8% by on-line infrared spectroscopy, and the graft layer thickness is measured by atomic force microscopy to be 5 - 20 nm.

4. A compatibilizer for improving the surface properties and interfacial adhesion of polyolefin elastomers according to claim 1, characterized in that, The amphiphilic block copolymer is polystyrene-b-polymethyl methacrylate or polyethylene-b-polyethylene oxide, with a molecular weight of 50,000 - 500,000 g / mol, where the hydrophilic segment accounts for 15 - 40%. The microphase separation structure has a periodic size of 10 - 50 nm measured by small-angle X-ray scattering.

5. A compatibilizer for improving the surface properties and interfacial adhesion of polyolefin elastomers according to claim 1, characterized in that, The radical initiator is a compound system of dicumyl peroxide and 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane, with a compound ratio of 1:0.5 - 1.

5. The difference between the half-life temperature and the processing temperature is controlled within ±5°C, and the decomposition activation energy is measured to be 120 - 150 kJ / mol by the Kissinger method.

6. A compatibilizer for improving the surface properties and interfacial adhesion of polyolefin elastomers according to claim 1, characterized in that The interface enhancer is a composite of nano-scale silica aerogel and ionic liquid, where the particle size of SiO2 is 10 - 50 nm, the specific surface area is 500 - 800 m 2 / g, the ionic liquid is 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, and the loading amount of the nano-scale silica aerogel is controlled at 15 - 30 wt% by the impregnation method.

7. A compatibilizer for improving the surface properties and interfacial adhesion of polyolefin elastomers according to claim 1, characterized in that, In the pre-swelling stage, supercritical CO2 with a pressure of 8 - 15 MPa, a temperature of 80 - 120°C, and a swelling time of 30 - 120 min is used. The swelling degree is measured to be 20 - 50% by the gravimetric method, and immediately after swelling, a quenching treatment is carried out to make the polar monomer orientedly distributed in the amorphous region of the elastomer.

8. A compatibilizer for improving the surface properties and interfacial adhesion of polyolefin elastomers according to claim 1, characterized in that, The length-to-diameter ratio L / D of the twin-screw extruder is ≥40, and it is equipped with a combination of reverse intermeshing blocks and pin mixing elements. The melt residence time is synergistically controlled at 2 - 5 min by the screw speed (100 - 300 rpm) and the feeding rate (5 - 20 kg / h), and the grafting reaction conversion rate is monitored by on-line Raman spectroscopy ≥85%.

9. The compatibilizer for improving the surface properties and interfacial adhesion of polyolefin elastomer according to claim 1, characterized in that The storage modulus G' of the final product is 1×10~5×10 at 190 °C 4 Pa, the peak temperature of the loss factor tanδ is 10 - 25 °C higher than that of the matrix, and the interfacial diffusion coefficient measured by neutron reflection method is 1×10 -16 ~5×10 -15 m 2 / s.

10. The compatibilizer for improving the surface properties and interfacial adhesion of polyolefin elastomer according to claim 1, characterized in that, When applied to automotive sealing strips, the peel strength from the polypropylene matrix is ≥ 35 N / cm, the retention rate of heat aging resistance (150 °C × 1000 h) is ≥ 80%, and the interfacial toughness at -40 °C is determined by the notched impact test to be ≥ 45 kJ / m 2 .

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