A low-temperature resistant PP composite board and its preparation method

Abstract

The present invention relates to a low-temperature resistant PP composite board and a preparation method thereof, and belongs to the technical field of polymer composite materials. The PP composite board includes the following raw materials by weight: 100 parts of PP resin, 13-18 parts of POE resin, 15-22 parts of glass fiber powder, 4-6 parts of compatibilizer, 0.65-0.82 parts of anti-low-temperature additive, 1.2-1.5 parts of lubricant and 0.1-0.12 parts of antioxidant; the anti-low-temperature additive is prepared by amidation reaction of terephthaloyl chloride and diethylenetriamine to form a small molecular weight chain amide compound, which is then replaced by (3-iodopropyl) trimethoxysilane and the imine structure in its molecular chain, and a methoxysilane structure is introduced to the side chain to replace; the introduction of the anti-low-temperature additive enables the composite board to have good low-temperature impact resistance and excellent creep resistance.

Description

Technical Field

[0001] The present invention belongs to the technical field of polymer composite materials, and in particular, relates to a low-temperature resistant PP composite board and a preparation method thereof. Background Art

[0002] Polypropylene (PP) is a polymer formed by the addition polymerization of propylene. It is a colorless and translucent thermoplastic plastic. It is abundant in source, inexpensive and widely used. It has become an indispensable general-purpose plastic in the plastics industry. Glass fiber reinforced polypropylene has improved heat resistance and significantly improved mechanical strength based on the original performance of polypropylene. Its relative density is much lower than that of metal materials and can be used for lightweight load-bearing parts.

[0003] However, the low-temperature impact performance of polypropylene is poor, and it is easy to be damaged when subjected to external force impact, which affects the stability of the product. In the prior art, a certain amount of β-nucleating agent is compounded into the polypropylene raw material to promote the production of a large number of high-toughness β-phase crystals in polypropylene, which can effectively improve the low-temperature resistance of the product to a certain extent. However, the β-crystal structure is relatively loose, the entanglement and interaction between the molecular chains are weak, and the interaction between the crystalline region and the amorphous region is weak, which causes the homogeneous polypropylene material formed by the blend to easily produce creep, resulting in poor structural stability of the product, which greatly limits the application of polypropylene materials. Summary of the invention

[0004] In order to solve the technical problems mentioned in the background technology, the object of the present invention is to provide a low-temperature resistant PP composite board and a preparation method thereof.

[0005] The purpose of the present invention can be achieved through the following technical solutions:

[0006] A low-temperature resistant PP composite board comprises the following raw materials in parts by weight: 100 parts of PP resin, 13-18 parts of POE resin, 15-22 parts of glass fiber powder, 4-6 parts of a compatibilizer, 0.65-0.82 parts of a low-temperature resistant additive, 1.2-1.5 parts of a lubricant, and 0.1-0.12 parts of an antioxidant;

[0007] The anti-low temperature additive is prepared by the following method:

[0008] Step A1: Diethylenetriamine, pyridine and anhydrous dioxane are mixed, dry nitrogen is introduced for protection, the water bath temperature is controlled at 40-55°C, stirring is applied at 60-90rpm, and a dichloromethane solution of terephthaloyl chloride is slowly added to react for 4-5h, then the temperature is raised to 100°C, and reflux is continued for 1.5-2h. After the reaction is completed, the dioxane is removed by rotary evaporation to obtain an amide intermediate;

[0009] Furthermore, the dosage ratio of terephthaloyl chloride, diethylenetriamine, pyridine and anhydrous dioxane is 10mmol:12-14mmol:0.8-1.1mL:25-35mL, and pyridine is used as an alkaline catalyst to promote the amidation reaction of terephthaloyl chloride and diethylenetriamine to prepare a small molecular weight chain amide compound.

[0010] Step A2: premix the amide intermediate and dimethylacetamide, pass dry nitrogen for protection, add (3-iodopropyl)trimethoxysilane and mix well, heat to 110-125°C, stir at 120-180 rpm, add potassium tert-butoxide dissolved in tetrahydrofuran intermittently, react for 3.5-5 hours, and remove dimethylacetamide by vacuum rotary evaporation after the reaction to obtain an anti-low temperature additive;

[0011] Furthermore, the usage ratio of the amide intermediate, (3-iodopropyl)trimethoxysilane, potassium tert-butoxide and dimethylacetamide is 10g:5-8mmol:30-50mg:30-40mL. Under the promotion of potassium tert-butoxide, (3-iodopropyl)trimethoxysilane replaces the active imine in the amide intermediate molecular chain, and methoxysilane is introduced for modification.

[0012] Preferably, the monofilament diameter of the glass fiber powder is not greater than 10 μm.

[0013] Preferably, the aspect ratio of the glass fiber powder is 5-20.

[0014] Preferably, the compatibilizer is selected from maleic anhydride grafted polypropylene.

[0015] Preferably, the lubricant is compounded from calcium stearate and polypropylene wax.

[0016] A method for preparing a low-temperature resistant PP composite board comprises the following steps:

[0017] Step S1: premix glass fiber powder, a compatibilizer, an anti-low temperature additive, a lubricant and an antioxidant at 150° C., melt-blend PP resin and POE resin at 185° C., add the premix and knead until the torque is stable, and pelletize the material to obtain a composite masterbatch;

[0018] Step S2: plasticizing and extruding the composite masterbatch, hot pressing, pulling and cooling, annealing and homogenizing, cutting and trimming in sequence to obtain a low-temperature resistant PP composite board.

[0019] Furthermore, the discharge temperature of the plasticizing extrusion is 210-220°C, the mold temperature of the hot pressing molding is 120±15°C, and the hot pressing molding pressure is 42-48MPa.

[0020] Furthermore, the annealing homogenization temperature is 90-110° C., and the time is 15-20 min.

[0021] Beneficial effects of the present invention:

[0022] The invention discloses a novel low-temperature resistant additive, which is prepared by amidation reaction of terephthaloyl chloride and diethylenetriamine to form a small molecular weight chain amide compound, and then (3-iodopropyl) trimethoxysilane is substituted with the imine structure in its molecular chain, and a methoxysilane structure is introduced into the side chain to replace it. The additive is applied to the existing glass fiber reinforced PP system. During melt blending, the methoxysilane structure of the side chain is coupled with the glass fiber, and the chain amide structure is grafted onto the surface of the glass fiber. The chain amide structure is used as a template to promote the formation of a large number of chain β-phase crystals of polypropylene on the surface of the glass fiber during the cooling process. Different from the existing β-nucleating agent, the β-phase crystals are formed from the glass fiber. The surface extends toward the polypropylene matrix and presents a gradient distribution, so that the high-rigidity glass fiber and the polypropylene matrix form a gradient toughness combination. When subjected to external force, a greater elastic deformation can be generated between the glass fiber and the polypropylene matrix, especially in a low-temperature environment. The β-phase crystal has excellent toughness and plays a good buffering and impact resistance role. On the other hand, the chain-like β-phase crystals are interwoven on the surface of the glass fiber, strengthening the bonding strength between the glass fiber and the polypropylene matrix, so that the glass fiber can fully play its role in fixing the polypropylene macromolecules, limiting the movement of the macromolecular chains under stress or external force, and increasing the stress threshold required for creep, thereby making the board's anti-creep performance better. DETAILED DESCRIPTION

[0023] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0024] Example 1, preparing a low temperature resistant PP composite board, the specific implementation process is as follows:

[0025] (1) Preparation of anti-low temperature additives

[0026] Step A1: Add diethylenetriamine, pyridine and anhydrous dioxane and mix them evenly, introduce dry nitrogen for protection, control the temperature of the water bath to 55°C, apply stirring at 90rpm, take terephthaloyl chloride and add dichloromethane to prepare a saturated solution, slowly add the dichloromethane solution of terephthaloyl chloride to the reaction system and react for 4 hours, then raise the temperature to 100°C and continue to reflux for 1.5 hours, wherein the amount ratio of terephthaloyl chloride, diethylenetriamine, pyridine and anhydrous dioxane is controlled to be 10mmol:12mmol:1.1mL:35mL, and after the reaction is completed, remove dioxane by rotary evaporation to obtain an amide intermediate.

[0027] Step A2: premix the amide intermediate and dimethylacetamide, pass dry nitrogen for protection, add (3-iodopropyl)trimethoxysilane and mix well, heat to 125°C, stir at 180rpm, take a tetrahydrofuran solution of potassium tert-butoxide with a molar concentration of 1 mol / L, divide it into five equal parts and add it to the reaction system intermittently for 15 minutes, control the total reaction time to be 3.5 hours, control the amount ratio of amide intermediate, (3-iodopropyl)trimethoxysilane, potassium tert-butoxide and dimethylacetamide to be 10g:5mmol:50mg:40mL, and remove dimethylacetamide by vacuum rotary evaporation after the reaction to obtain an anti-low temperature additive.

[0028] (2) Preparation of low temperature resistant PP composite board

[0029] Ingredients: The raw materials are calculated by weight: 100 parts of PP resin, HP500N homopolypropylene is selected; 15 parts of POE (ethylene-octene copolymer) resin is selected from ENGAGE™ POE 8401 resin raw material; 22 parts of glass fiber powder is selected from XGFT9300 raw material, the calibrated single fiber diameter is 9 μm, and the aspect ratio is 5.5:1; 6 parts of compatibilizer is selected from Exxelor PO 1020 maleic anhydride grafted polypropylene; 0.82 parts of low temperature anti-additive is self-made in this embodiment; 1.5 parts of lubricant is compounded by TW-F2051 polypropylene wax and industrial grade calcium stearate at a weight ratio of 2:1; 0.1 parts of antioxidant is selected from antioxidant 1010 and antioxidant 168 in an equal mass ratio.

[0030] Step S1: premix glass fiber powder, compatibilizer, anti-low temperature additive, lubricant and antioxidant at 150°C for 10 minutes, add PP resin and POE resin into a torque rheometer, melt blend at 185°C, add the premix and knead until the torque is stable, discharging and pelletizing to obtain a composite masterbatch.

[0031] Step S2: plasticize and extrude the composite masterbatch using a twin-screw extruder, control the discharge temperature to 210°C, extrude the plasticized material into a plate making machine for hot pressing, set the mold temperature to 120°C, allow the error to be 15°C, control the pressure of hot pressing to 42MPa, cool the hot-pressed plate by traction, and then transfer it to a tunnel annealing furnace, control the temperature to 90°C, anneal and homogenize for 20 minutes, and finally cut and trim to obtain a low-temperature resistant PP composite plate.

[0032] Example 2, preparing a low temperature resistant PP composite board, the specific implementation process is as follows:

[0033] (1) Preparation of anti-low temperature additives

[0034] Step A1: Add diethylenetriamine, pyridine and anhydrous dioxane and mix them evenly, introduce dry nitrogen for protection, control the temperature in a water bath to 40°C, apply stirring at 60rpm, take terephthaloyl chloride and add dichloromethane to prepare a saturated solution, slowly add the dichloromethane solution of terephthaloyl chloride to the reaction system and react for 5 hours, then raise the temperature to 100°C and continue to reflux for 2 hours, wherein the amount ratio of terephthaloyl chloride, diethylenetriamine, pyridine and anhydrous dioxane is controlled to be 10mmol:14mmol:0.8mL:25mL, and after the reaction is completed, remove dioxane by rotary evaporation to obtain an amide intermediate.

[0035] Step A2: premix the amide intermediate and dimethylacetamide, pass dry nitrogen for protection, add (3-iodopropyl)trimethoxysilane and mix well, heat to 110°C, stir at 120rpm, take a tetrahydrofuran solution of potassium tert-butoxide with a molar concentration of 1 mol / L, divide it into five equal parts and add it to the reaction system intermittently for 30 minutes, control the total reaction time to be 5 hours, control the amount ratio of amide intermediate, (3-iodopropyl)trimethoxysilane, potassium tert-butoxide and dimethylacetamide to be 10g:8mmol:30mg:30mL, and remove dimethylacetamide by vacuum rotary evaporation after the reaction to obtain an anti-low temperature additive.

[0036] (2) Preparation of low temperature resistant PP composite board

[0037] Ingredients: The raw materials are calculated by weight: 100 parts of PP resin, HP500N homopolymer polypropylene is selected; 18 parts of POE resin, selected from ENGAGE™ POE 8401 resin raw material; 15 parts of glass fiber powder, selected from XGFT9100 raw material, with a calibrated single filament diameter of 9 μm and an aspect ratio of 18:1; 4 parts of compatibilizer, selected from Exxelor PO 1020 maleic anhydride grafted polypropylene; 0.65 parts of low temperature anti-additive, which is self-made in this embodiment; 1.2 parts of lubricant, compounded by TW-F2051 polypropylene wax and industrial grade calcium stearate at a weight ratio of 2:1; 0.12 parts of antioxidant, selected from antioxidant 1010 and antioxidant 168 in an equal mass ratio.

[0038] Step S1: premix glass fiber powder, compatibilizer, anti-low temperature additive, lubricant and antioxidant at 150°C for 10 minutes, add PP resin and POE resin into a torque rheometer, melt blend at 185°C, add the premix and knead until the torque is stable, discharging and pelletizing to obtain a composite masterbatch.

[0039] Step S2: plasticize and extrude the composite masterbatch using a twin-screw extruder, control the discharge temperature to 220°C, extrude the plasticized material into a plate making machine for hot pressing, set the mold temperature to 120°C, allow the error to be 15°C, control the hot pressing pressure to 48MPa, cool the hot-pressed plate by traction, and then transfer it to a tunnel annealing furnace, control the temperature to 110°C, anneal and homogenize for 15 minutes, and finally cut and trim to obtain a low-temperature resistant PP composite plate.

[0040] Example 3, preparing a low temperature resistant PP composite board, the specific implementation process is as follows:

[0041] (1) Preparation of anti-low temperature additives

[0042] Step A1: Add diethylenetriamine, pyridine and anhydrous dioxane and mix them evenly, introduce dry nitrogen for protection, control the temperature in a water bath to 45°C, apply stirring at 60rpm, take terephthaloyl chloride and add dichloromethane to prepare a saturated solution, slowly add the dichloromethane solution of terephthaloyl chloride to the reaction system and react for 4.5h, then raise the temperature to 100°C, and continue to reflux for 1.7h, wherein the amount ratio of terephthaloyl chloride, diethylenetriamine, pyridine and anhydrous dioxane is controlled to be 10mmol:12mmol:1mL:30mL, and after the reaction is completed, remove dioxane by rotary evaporation to obtain an amide intermediate.

[0043] Step A2: premix the amide intermediate and dimethylacetamide, pass dry nitrogen for protection, add (3-iodopropyl)trimethoxysilane and mix well, heat to 120°C, stir at 180rpm, take a tetrahydrofuran solution of potassium tert-butoxide with a molar concentration of 1 mol / L, divide it into five equal parts and add it to the reaction system intermittently for 20 minutes, control the total reaction time to be 4 hours, control the amount ratio of amide intermediate, (3-iodopropyl)trimethoxysilane, potassium tert-butoxide and dimethylacetamide to be 10g:7mmol:40mg:35mL, and remove dimethylacetamide by vacuum rotary evaporation after the reaction to obtain an anti-low temperature additive.

[0044] (2) Preparation of low temperature resistant PP composite board

[0045] Ingredients: The raw materials are calculated by weight: 100 parts of PP resin, HP500N homopolymer polypropylene is selected; 13 parts of POE resin, selected from ENGAGE™ POE 8401 resin raw material; 18 parts of glass fiber powder, selected from XGFT9200 raw material, with a calibrated single filament diameter of 9 μm and an aspect ratio of 8:1; 5 parts of compatibilizer, selected from Exxelor PO 1020 maleic anhydride grafted polypropylene; 0.75 parts of low temperature anti-additive, which is self-made in this embodiment; 1.4 parts of lubricant, compounded by TW-F2051 polypropylene wax and industrial grade calcium stearate at a weight ratio of 2:1; 0.1 parts of antioxidant, selected from antioxidant 1010 and antioxidant 168 in an equal mass ratio.

[0046] Step S1: premix glass fiber powder, compatibilizer, anti-low temperature additive, lubricant and antioxidant at 150°C for 10 minutes, add PP resin and POE resin into a torque rheometer, melt blend at 185°C, add the premix and knead until the torque is stable, discharging and pelletizing to obtain a composite masterbatch.

[0047] Step S2: plasticize and extrude the composite masterbatch using a twin-screw extruder, control the discharge temperature to 210°C, extrude the plasticized material into a plate making machine for hot pressing, set the mold temperature to 120°C, allow the error to be 15°C, control the hot pressing pressure to 45MPa, cool the hot-pressed plate by traction, and then transfer it to a tunnel annealing furnace, control the temperature to 100°C, anneal and homogenize for 18 minutes, and finally cut and trim to obtain a low-temperature resistant PP composite plate.

[0048] Example 4, preparing a low temperature resistant PP composite board, the specific implementation process is as follows:

[0049] (1) Preparation of anti-low temperature additives

[0050] Step A1: Add diethylenetriamine, pyridine and anhydrous dioxane and mix them evenly, introduce dry nitrogen for protection, control the temperature of the water bath to 52°C, apply stirring at 90rpm, take terephthaloyl chloride and add dichloromethane to prepare a saturated solution, slowly add the dichloromethane solution of terephthaloyl chloride to the reaction system and react for 4.5h, then raise the temperature to 100°C, and continue to reflux for 1.5h, wherein the amount ratio of terephthaloyl chloride, diethylenetriamine, pyridine and anhydrous dioxane is controlled to be 10mmol:13mmol:1.1mL:30mL, and after the reaction is completed, remove dioxane by rotary evaporation to obtain an amide intermediate.

[0051] Step A2: premix the amide intermediate and dimethylacetamide, pass dry nitrogen for protection, add (3-iodopropyl)trimethoxysilane and mix well, heat to 120°C, stir at 150rpm, take a tetrahydrofuran solution of potassium tert-butoxide with a molar concentration of 1 mol / L, divide it into five equal parts and add it to the reaction system intermittently for 25 minutes, control the total reaction time to be 5 hours, control the amount ratio of amide intermediate, (3-iodopropyl)trimethoxysilane, potassium tert-butoxide and dimethylacetamide to be 10g:7mmol:35mg:40mL, and remove dimethylacetamide by vacuum rotary evaporation after the reaction to obtain an anti-low temperature additive.

[0052] (2) Preparation of low temperature resistant PP composite board

[0053] Ingredients: The raw materials are calculated by weight: 100 parts of PP resin, HP500N homopolymer polypropylene is selected; 14 parts of POE resin, selected from ENGAGE™ POE 8401 resin raw material; 20 parts of glass fiber powder, selected from XGFT9200 raw material, with a calibrated single filament diameter of 9 μm and an aspect ratio of 8:1; 5 parts of compatibilizer, selected from Exxelor PO 1020 maleic anhydride grafted polypropylene; 0.8 parts of low temperature anti-additive, which is self-made in this embodiment; 1.3 parts of lubricant, compounded by TW-F2051 polypropylene wax and industrial grade calcium stearate at a weight ratio of 2:1; 0.1 parts of antioxidant, selected from antioxidant 1010 and antioxidant 168, compounded in an equal mass ratio.

[0054] Step S1: premix glass fiber powder, compatibilizer, anti-low temperature additive, lubricant and antioxidant at 150°C for 10 minutes, add PP resin and POE resin into a torque rheometer, melt blend at 185°C, add the premix and knead until the torque is stable, discharging and pelletizing to obtain a composite masterbatch.

[0055] Step S2: plasticize and extrude the composite masterbatch using a twin-screw extruder, control the discharge temperature to 220°C, extrude the plasticized material into a plate making machine for hot pressing, set the mold temperature to 120°C, allow the error to be 15°C, control the hot pressing pressure to 45MPa, cool the hot-pressed plate by traction, and then transfer it to a tunnel annealing furnace, control the temperature to 110°C, anneal and homogenize for 15 minutes, and finally cut and trim to obtain a low-temperature resistant PP composite plate.

[0056] As a comparative example, referring to Example 4, the anti-low temperature additive is replaced by 0.2 parts of silane coupling agent KH-570 and 0.7 parts of nucleating agent TMB-5, and the rest of the implementation process is exactly the same.

[0057] Samples were taken from the plate prepared as above, and tensile tests were carried out according to GB / T 1040.1-2018; bending tests were carried out according to GB / T9341-2008; impact tests were carried out according to GB / T 1843-2008, and the test temperature was -10°C; tensile creep tests were carried out according to GB / T11546.1-2008, and the tensile stress level was 10MPa, the test cycle was 72h, and the creep strain was detected after standing for 24h; the specific test results are shown in Table 1:

[0058]

[0059] It can be seen from the test results in Table 1 that the composite board prepared in the embodiment has good low-temperature impact resistance, high tensile strength and flexural modulus, and especially significantly improved creep resistance.

[0060] In the description of the specification, the description with reference to the terms "one embodiment", "example", "specific example", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0061] The above contents are merely examples and explanations of the present invention. Those skilled in the art may make various modifications or additions to the specific embodiments described or replace them in a similar manner. As long as they do not deviate from the invention or exceed the scope defined by the claims, they shall all fall within the protection scope of the present invention.

Claims

1. A low temperature resistant PP composite board, characterized in that: The following raw materials are included in parts by weight: 100 parts of PP resin, 13-18 parts of POE resin, 15-22 parts of glass fiber powder, 4-6 parts of compatibilizer, 0.65-0.82 parts of anti-low temperature additive, 1.2-1.5 parts of lubricant and 0.1-0.12 parts of antioxidant; The anti-low temperature additive is prepared by the following method: Step A1: Diethylenetriamine, pyridine and anhydrous dioxane are mixed, dry nitrogen is introduced for protection, the water bath temperature is controlled at 40-55°C, and terephthaloyl chloride dissolved in dichloromethane is slowly added with stirring to react for 4-5h, then the temperature is raised to 100°C, and reflux is continued for 1.5-2h. After the reaction is completed, the dioxane is removed by rotary evaporation to obtain an amide intermediate; Step A2: premix the amide intermediate and dimethylacetamide, pass dry nitrogen for protection, add (3-iodopropyl)trimethoxysilane and mix well, raise the temperature to 110-125°C, stir and intermittently add potassium tert-butoxide dissolved in tetrahydrofuran to react for 3.5-5h, and after the reaction is completed, remove dimethylacetamide by vacuum rotary evaporation to obtain an anti-low temperature additive.

2. A low temperature resistant PP composite board according to claim 1, characterized in that: The usage ratio of terephthaloyl chloride, diethylenetriamine, pyridine and anhydrous dioxane is 10mmol:12-14mmol:0.8-1.1mL:25-35mL.

3. A low temperature resistant PP composite board according to claim 2, characterized in that: The usage ratio of the amide intermediate, (3-iodopropyl)trimethoxysilane, potassium tert-butoxide and dimethylacetamide is 10 g: 5-8 mmol: 30-50 mg: 30-40 mL.

4. The low temperature resistant PP composite board according to claim 1, characterized in that: The monofilament diameter of the glass fiber powder is not higher than 10 μm.

5. The low temperature resistant PP composite board according to claim 4, characterized in that: The aspect ratio of the glass fiber powder is 5-20.

6. The method for preparing a low temperature resistant PP composite board according to any one of claims 1 to 5, characterized in that: The steps include: Step S1: premix glass fiber powder, a compatibilizer, an anti-low temperature additive, a lubricant and an antioxidant at 150° C., melt-blend PP resin and POE resin at 185° C., add the premix and knead until the torque is stable, and pelletize the material to obtain a composite masterbatch; Step S2: plasticizing and extruding the composite masterbatch, hot pressing, pulling and cooling, annealing and homogenizing, cutting and trimming in sequence to obtain a low-temperature resistant PP composite board.

7. The method for preparing a low-temperature resistant PP composite board according to claim 6, characterized in that: The discharge temperature of plasticizing extrusion is 210-220°C, the mold temperature of hot pressing molding is 120±15°C, and the hot pressing molding pressure is 42-48MPa.

8. The method for preparing a low-temperature resistant PP composite board according to claim 7, characterized in that: The annealing homogenization temperature is 90-110°C and the time is 15-20 minutes.

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