A masterbatch and manufacturing process for high modulus thin films

Abstract

This invention relates to the field of polypropylene technology and discloses a high-modulus film masterbatch and its production process. The alkyl long chains contained in the hyperbranched polyquaternary ammonium salt exhibit excellent compatibility with polypropylene, improving its mechanical properties. The hyperbranched polyquaternary ammonium salt uniformly coats graphene, improving the compatibility between graphene and polypropylene and allowing graphene to better exert its reinforcing and modifying effects, significantly improving the tensile and flexural strength of polypropylene. The alkyl quaternary ammonium salt antibacterial groups contained in the hyperbranched polyquaternary ammonium salt provide excellent bactericidal effects, giving the polypropylene masterbatch superior antibacterial properties. The high-modulus polypropylene masterbatch can be processed through biaxial stretching, blow molding, and casting to produce high-modulus, high-strength, and antibacterial polypropylene films, which have excellent applications in packaging films, bags, agricultural films, and antibacterial film materials.

Description

Technical Field

[0001] This invention relates to the field of polypropylene technology, specifically to a masterbatch and production process for high-modulus films. Background Technology

[0002] Polypropylene (PP) film possesses excellent transparency, physical stability, and airtightness, making it widely used in packaging films, bags, and agricultural films. Improving the strength, modulus, and other mechanical properties of PP and its film materials, and endowing them with antibacterial properties, helps extend their service life and expands their practical applications in food preservation films and medical antibacterial products. For example, CN113372653B discloses a graphene-PP-PET composite system for stiffening masterbatch in BOPP film. In this system, PP, PET, and graphene form a molten community through chemical bonds, producing a synergistic effect. The resulting BOPP film has higher rigidity and faster processing speed. However, this patent does not impart antibacterial properties to the PP film. Patent CN113512220B discloses using epoxy-based cage-type polysilsesquioxane, pretreated nano-titanium dioxide, 11-chloro-1-undecene, etc., as raw materials to prepare modified polysilsesquioxane B grafted with titanium dioxide and unsaturated quaternary ammonium salt, which is then compounded with polypropylene to produce polypropylene plastic packaging film material with good antibacterial properties. However, this patent does not significantly improve the strength and modulus of polypropylene film material. Summary of the Invention

[0003] Technical problem solved: A functionalized graphene and hyperbranched polyquaternary ammonium salt were prepared to fill and modify polypropylene, resulting in a high-strength, high-modulus, and antibacterial high-modulus polypropylene film masterbatch.

[0004] The technical solution is as follows:

[0005] A high-modulus film masterbatch comprises the following components: 100 parts by weight of polypropylene resin, 0.5-3 parts by weight of functionalized graphene, 2-8 parts by weight of hyperbranched polyquaternary ammonium salt, and 0.2-0.6 parts by weight of antioxidant.

[0006] The production process of high-modulus film masterbatch includes the following steps: 100 parts by weight of polypropylene resin, 0.5-3 parts by weight of functionalized graphene, 2-8 parts by weight of hyperbranched polyquaternary ammonium salt, and 0.2-0.6 parts by weight of antioxidant are added to a twin-screw extruder for co-extrusion at a five-stage temperature of 175-190℃, followed by granulation to obtain the high-modulus film masterbatch. The high-modulus film masterbatch is then used to produce polypropylene films through biaxial stretching, blow molding, and casting processes.

[0007] The production process of functionalized graphene includes the following steps: reacting graphene oxide with 4,4-diphenylmethane diisocyanate to obtain isocyanate graphene; dispersing the isocyanate graphene in any one of N,N-dimethylformamide, tetrahydrofuran, or 1,4-dioxane as a reaction solvent; adding citric acid; heating to 65-90℃ and reacting for 12-24 hours; cooling to the heating point; adding sodium hydroxide solution to adjust the pH to 9-11; filtering the solvent; and washing with water to obtain functionalized graphene.

[0008] Of this, the mass of citric acid is (70-200)% of the mass of isocyanate-based graphene.

[0009] The production process of hyperbranched polyquaternary ammonium salts includes the following steps: [The text abruptly ends here, so the translation stops.] Diphenylmethane di(ureidoimidazoleacetic acid) monomer and trimethylolpropane were added to N,N-dimethylformamide, heated to 130-145℃, p-toluenesulfonic acid was added under a nitrogen atmosphere, and the reaction was carried out for 3-5 hours. The mixture was then cooled to 110-125℃, an alkyl bromide compound was added, and the reaction was continued for 48-96 hours. The mixture was cooled to room temperature, and the solution was poured into methanol to precipitate the precipitate. The precipitate was filtered and washed with ethanol to obtain hyperbranched polyquaternary ammonium salt.

[0010] The molar amounts of trimethylolpropane and the alkyl bromide compound are (62-70)% and (210-260)% of the molar amounts of diphenylmethane di(ureidoimidazole acetic acid) monomer, respectively; the molecular formula of the alkyl bromide compound is C2. n H 2n+1 Br and n are any integers from 10 to 18.

[0011] The production process of diphenylmethane di(ureidoimidazole acetic acid) monomer includes the following steps:

[0012] (1) Add 3-chloro-L-alanine and 4,4-diphenylmethane diisocyanate to the solvent, heat to 60-80℃, react for 3-5 h, concentrate under reduced pressure, wash with n-hexane to obtain diphenylmethane di(ureochloroacetic acid) intermediate.

[0013] (2) Add diphenylmethane di(ureachloroacetic acid) intermediate, imidazole and potassium carbonate to acetonitrile, heat to 65-80℃, react for 3-8h, concentrate under reduced pressure, wash with water, and recrystallize in ethyl acetate to obtain diphenylmethane di(ureaimidazoleacetic acid) monomer.

[0014] Among them, the solvent in (1) includes tetrahydrofuran and 1,4-dioxane.

[0015] Among them, the molar amount of 3-chloro-L-alanine in (1) is (200-230)% of the molar amount of 4,4-diphenylmethane diisocyanate.

[0016] In (2), the molar amounts of imidazole and potassium carbonate are (210-250)% and (320-420)% of the molar amount of diphenylmethane di(ureochloroacetic acid) intermediate, respectively.

[0017] Technical Effects: This invention utilizes the reaction between the hydroxyl groups of citric acid and the isocyanate groups of isocyanate-based graphene to introduce abundant carboxyl groups onto the graphene surface. Following sodium hydroxide alkalization, abundant sodium carboxylate groups are generated. This achieves the functional modification of graphene.

[0018] This invention uses 3-chloro-L-alanine, 4,4-diphenylmethane diisocyanate, imidazole, etc. as reactants to prepare a novel diphenylmethane di(ureidoimidazole acetic acid) monomer, which undergoes hyperbranched esterification polymerization with trimethylolpropane, and then quaternization reaction with imidazole using alkyl bromide compounds to obtain a novel hyperbranched polyquaternary ammonium salt.

[0019] This invention utilizes functionalized graphene and hyperbranched polyquaternary ammonium salts to modify polypropylene. The long alkyl chains in the hyperbranched polyquaternary ammonium salt exhibit excellent compatibility with polypropylene. The branched long chains in the hyperbranched polyquaternary ammonium salt form physical crosslinks with polypropylene, improving its mechanical properties. Simultaneously, the functionalized graphene surface contains sodium carboxylate groups, which can electrostatically interact with the cations in the hyperbranched polyquaternary ammonium salt. Furthermore, the urea groups in the hyperbranched polyquaternary ammonium salt form hydrogen bonds with the urethane groups on the surface of the functionalized graphene, resulting in uniform coating of graphene by the hyperbranched polyquaternary ammonium salt. This allows the hyperbranched polyquaternary ammonium salt to act as a compatibilizer, improving the compatibility between graphene and polypropylene, enabling graphene to better exert its reinforcing and modifying effect, and significantly improving the tensile and flexural strength of polypropylene.

[0020] The hyperbranched polyquaternary ammonium salt of the present invention has good compatibility with polypropylene and is uniformly dispersed in the polypropylene matrix. The alkyl quaternary ammonium salt antibacterial groups contained therein can interact with the cell membrane of bacteria, thereby destroying the permeability of the cell membrane and causing substances inside the cell membrane to flow out, thereby affecting the normal metabolism and reproduction of bacteria, achieving excellent bactericidal effect, and making the polypropylene masterbatch exhibit excellent antibacterial properties.

[0021] The high-modulus polypropylene masterbatch of this invention can be processed into high-modulus, high-strength, and antibacterial polypropylene films through biaxial stretching, blow molding, casting, and other processes, and has excellent applications in packaging films, packaging bags, agricultural films, and antibacterial film materials. Simultaneously, it can be processed into high-performance polypropylene plastics through injection molding and other processes. Attached Figure Description

[0022] Figure 1 This is the reaction route for the preparation of diphenylmethane di(ureidoimidazole acetic acid) monomer.

[0023] Figure 2 This is the reaction route for the preparation of hyperbranched polyquaternary ammonium salts. Detailed Implementation

[0024] 0.5 g of graphene oxide was placed in 50 mL of toluene, and 1 g of 4,4-diphenylmethane diisocyanate was added. The mixture was heated to reflux under nitrogen atmosphere and reacted for 3 h. After filtration and washing with acetone, graphene isocyanate was obtained.

[0025] Example 1

[0026] 1g of isocyanate-based graphene was dispersed in tetrahydrofuran solvent, 0.7g of citric acid was added, the mixture was heated to 90℃ and reacted for 12h, then cooled to the desired temperature, sodium hydroxide solution was added to adjust the pH to 9, the solvent was filtered, and the mixture was washed with water to obtain functionalized graphene.

[0027] 11.5 mmol of 3-chloro-L-alanine and 5 mmol of 4,4-diphenylmethane diisocyanate were added to tetrahydrofuran, the mixture was heated to 60 °C and reacted for 4 h. The mixture was then concentrated under reduced pressure and washed with hexane to obtain diphenylmethane di(ureochloroacetic acid) intermediate.

[0028] 10 mmol of diphenylmethane di(ureochloroacetic acid) intermediate, 23 mmol of imidazole, and 34 mmol of potassium carbonate were added to acetonitrile. The mixture was heated to 80 °C and reacted for 5 h. After concentration under reduced pressure, the mixture was washed with water and recrystallized in ethyl acetate to obtain diphenylmethane di(ureoimidazoleacetic acid) monomer.

[0029] 10 mmol of diphenylmethane di(ureidoimidazoleacetic acid) monomer and 6.2 mmol of trimethylolpropane were added to N,N-dimethylformamide, the temperature was raised to 140 °C, 0.12 mmol of p-toluenesulfonic acid was added under a nitrogen atmosphere, the reaction was carried out for 5 h, cooled to 125 °C, 26 mmol of 1-bromodecane was added, the reaction was continued for 96 h, cooled to room temperature, the solution was poured into methanol to precipitate the precipitate, filtered, washed with ethanol, and hyperbranched polyquaternary ammonium salt was obtained.

[0030] 1000g of polypropylene resin, 5g of functionalized graphene, 20g of hyperbranched polyquaternary ammonium salt, and 6g of antioxidant 1076 were added to a twin-screw extruder for co-extrusion. The temperature was set at five stages: 175℃, 185℃, 190℃, 190℃, and 180℃. Granulation was then carried out to obtain a high-modulus film masterbatch.

[0031] Example 2

[0032] 1g of isocyanate-based graphene was dispersed in N,N-dimethylformamide solvent, 1.3g of citric acid was added, the mixture was heated to 75℃ and reacted for 24h, cooled to the heating point, and sodium hydroxide solution was added to adjust the pH to 10. The solvent was filtered, and the mixture was washed with water to obtain functionalized graphene.

[0033] 10 mmol of 3-chloro-L-alanine and 5 mmol of 4,4-diphenylmethane diisocyanate were added to a 1,4-dioxane solvent, the mixture was heated to 60 °C and reacted for 5 h. The mixture was then concentrated under reduced pressure and washed with hexane to obtain a diphenylmethane di(ureochloroacetic acid) intermediate.

[0034] 10 mmol of diphenylmethane di(ureochloroacetic acid) intermediate, 25 mmol of imidazole, and 32 mmol of potassium carbonate were added to acetonitrile. The mixture was heated to 80 °C and reacted for 3 h. After concentration under reduced pressure, the mixture was washed with water and recrystallized in ethyl acetate to obtain diphenylmethane di(ureoimidazoleacetic acid) monomer.

[0035] 10 mmol of diphenylmethane di(ureidoimidazoleacetic acid) monomer and 6.2 mmol of trimethylolpropane were added to N,N-dimethylformamide, the temperature was raised to 145 °C, 0.12 mmol of p-toluenesulfonic acid was added under a nitrogen atmosphere, the reaction was carried out for 3 h, cooled to 125 °C, 21 mmol of 1-bromododecane was added, the reaction was continued for 96 h, cooled to room temperature, the solution was poured into methanol to precipitate the precipitate, filtered, washed with ethanol, and hyperbranched polyquaternary ammonium salt was obtained.

[0036] 1000g of polypropylene resin, 18g of functionalized graphene, 50g of hyperbranched polyquaternary ammonium salt, and 4g of antioxidant 1076 were added to a twin-screw extruder for co-extrusion. The five-stage temperatures were 175℃, 185℃, 190℃, 190℃, and 180℃. Granulation was then carried out to obtain a high-modulus film masterbatch.

[0037] Example 3

[0038] 1g of isocyanate-based graphene was dispersed in a 1,4-dioxane solvent, 2g of citric acid was added, the mixture was heated to 65℃ and reacted for 24h, cooled to the heating point, and sodium hydroxide solution was added to adjust the pH to 11. The solvent was filtered, and the mixture was washed with water to obtain functionalized graphene.

[0039] 10 mmol of 3-chloro-L-alanine and 5 mmol of 4,4-diphenylmethane diisocyanate were added to a 1,4-dioxane solvent, the mixture was heated to 80 °C and reacted for 3 h. The mixture was then concentrated under reduced pressure and washed with hexane to obtain a diphenylmethane di(ureochloroacetic acid) intermediate.

[0040] 10 mmol of diphenylmethane di(ureochloroacetic acid) intermediate, 21 mmol of imidazole, and 34 mmol of potassium carbonate were added to acetonitrile. The mixture was heated to 65 °C and reacted for 8 h. After concentration under reduced pressure, the mixture was washed with water and recrystallized in ethyl acetate to obtain diphenylmethane di(ureoimidazoleacetic acid) monomer.

[0041] 10 mmol of diphenylmethane di(ureidoimidazoleacetic acid) monomer and 7 mmol of trimethylolpropane were added to N,N-dimethylformamide, heated to 130 °C, and 0.18 mmol of p-toluenesulfonic acid were added under a nitrogen atmosphere. The reaction was carried out for 4 h, cooled to 125 °C, and 26 mmol of 1-bromooctadecane was added. The reaction was continued for 48 h, cooled to room temperature, and the solution was poured into methanol to precipitate the precipitate. The precipitate was filtered and washed with ethanol to obtain hyperbranched polyquaternary ammonium salt.

[0042] 1000g of polypropylene resin, 30g of functionalized graphene, 80g of hyperbranched polyquaternary ammonium salt, and 2g of antioxidant 1076 were added to a twin-screw extruder for co-extrusion. The five-stage temperatures were 175℃, 185℃, 190℃, 190℃, and 180℃. Granulation was then carried out to obtain a high-modulus film masterbatch.

[0043] Comparative Example 1 was prepared without the addition of functionalized graphene and hyperbranched polyquaternary ammonium salt.

[0044] 1000g of polypropylene resin and 6g of antioxidant 1076 were added to a twin-screw extruder for co-extrusion. The temperature was set at five stages: 175℃, 185℃, 190℃, 190℃, and 180℃. Granulation was then carried out to obtain a high-modulus film masterbatch.

[0045] The difference between Comparative Example 2 and Example 1 is that no functionalized graphene is added.

[0046] 1000g of polypropylene resin, 20g of hyperbranched polyquaternary ammonium salt, and 6g of antioxidant 1076 were added to a twin-screw extruder for co-extrusion. The temperature was set at five stages: 175℃, 185℃, 190℃, 190℃, and 180℃. Granulation was then carried out to obtain a high-modulus film masterbatch.

[0047] The difference between Comparative Example 3 and Example 1 is the addition of ordinary graphene oxide.

[0048] 1000g of polypropylene resin, 5g of graphene oxide, 20g of hyperbranched polyquaternary ammonium salt, and 6g of antioxidant 1076 were added to a twin-screw extruder for co-extrusion. The temperature was set at five stages: 175℃, 185℃, 190℃, 190℃, and 180℃. Granulation was then carried out to obtain a high-modulus film masterbatch.

[0049] The difference between Comparative Example 4 and Example 1 is that hyperbranched polyquaternary ammonium salts are not added.

[0050] 1000g of polypropylene resin, 5g of functionalized graphene, and 6g of antioxidant 1076 were added to a twin-screw extruder for co-extrusion. The temperature was set at five stages: 175℃, 185℃, 190℃, 190℃, and 180℃. Granulation was then carried out to obtain a high-modulus film masterbatch.

[0051] Polypropylene masterbatch was injection molded to make standard specimens, and the tensile and flexural properties of the composite material were tested according to the methods of GB / T1040.1-2018 and GB / T9341-2008.

[0052]

[0053] In each embodiment, functionalized graphene and hyperbranched polyquaternary ammonium salts are used to modify polypropylene. The long alkyl chains in the hyperbranched polyquaternary ammonium salts have excellent compatibility with polypropylene. The branched long chains in the hyperbranched polyquaternary ammonium salts form physical crosslinks with polypropylene, which can improve the mechanical properties of polypropylene. Simultaneously, the functionalized graphene surface also has sodium carboxylate groups, which can electrostatically interact with the cations of the hyperbranched polyquaternary ammonium salts, and the urea groups in the hyperbranched polyquaternary ammonium salts... With the urethane groups on the surface of functionalized graphene Hydrogen bonds form between the graphene and polypropylene, allowing the hyperbranched polyquaternary ammonium salt to uniformly coat the graphene. This hyperbranched polyquaternary ammonium salt acts as a compatibilizer, improving the compatibility between graphene and polypropylene, enabling graphene to better exert its reinforcing and modifying effects, and significantly improving the tensile and flexural strength of polypropylene. The tensile strength reaches 44.4-57.6 MPa, the flexural strength reaches 58.1-72.3 MPa, and the flexural modulus reaches 2.21-2.44 GPa.

[0054] Comparative Example 1, which did not contain functionalized graphene or hyperbranched polyquaternary ammonium salt, showed the lowest mechanical strength and modulus of polypropylene. Comparative Example 2, which also did not contain functionalized graphene, showed poor strength and modulus of polypropylene.

[0055] Comparative Example 3 incorporated ordinary graphene oxide, which could not interact with hyperbranched polyquaternary ammonium salts and exhibited poor compatibility with polypropylene. Comparative Example 4 did not incorporate hyperbranched polyquaternary ammonium salts, and the compatibility of the functionalized graphene with polypropylene was lower than in the other examples; neither example effectively utilized the reinforcing and modifying effects of graphene. The mechanical strength and modulus of the polypropylene were lower than in the other examples.

[0056] Antibacterial performance test of polypropylene masterbatch: The polypropylene masterbatches prepared in Examples 1-3 and Comparative Examples 2-4 were used as the experimental group, and the polypropylene masterbatch of Comparative Example 1 was used as the control group; the polypropylene masterbatch was biaxially stretched to form polypropylene films, and the polypropylene films were added to a solution with a concentration of 2×10⁻⁶. 6 In a CFU / mL E. coli culture, the culture was shaken at 37°C for 10-60 min. 0.2 mL of the culture was then transferred using a pipette to phosphate buffer for serial dilution. Another 0.2 mL of the diluted culture was then evenly spread onto the surface of an agar medium and incubated at 37°C for 24 h. After incubation, viable cell counts were performed, and the antibacterial rate A was calculated. Antibacterial rate A = (BC) / B, where B is the bacterial count in the control group and C is the bacterial count in the experimental group.

[0057]

[0058]

[0059] Examples 1-3 and Comparative Examples 2-3 all incorporated hyperbranched polyquaternium salts. The hyperbranched polyquaternium salts were uniformly dispersed in the polypropylene matrix. The alkyl quaternary ammonium salt antibacterial groups contained therein could interact with the bacterial cell membrane, thereby disrupting the cell membrane permeability and causing substances inside the cell membrane to flow out, thus affecting the normal metabolism and reproduction of bacteria and achieving excellent bactericidal effect, making the polypropylene masterbatch exhibit excellent antibacterial properties.

Claims

1. A masterbatch for high-modulus thin films, characterized in that, The high-modulus film masterbatch comprises the following components: 100 parts by weight of polypropylene resin, 0.5-3 parts by weight of functionalized graphene, 2-8 parts by weight of hyperbranched polyquaternary ammonium salt, and 0.2-0.6 parts by weight of antioxidant; the high-modulus film masterbatch is used to produce polypropylene film material through biaxial stretching, blow molding, and casting processes. The production process of the functionalized graphene includes the following steps: reacting graphene oxide with 4,4-diphenylmethane diisocyanate to obtain isocyanate graphene; dispersing the isocyanate graphene in a reaction solvent, adding citric acid, heating to 65-90℃ and reacting for 12-24 hours, cooling to the heating point, adding sodium hydroxide solution to adjust the pH to 9-11, filtering the solvent, washing, and obtaining functionalized graphene; The production process of the hyperbranched polyquaternary ammonium salt includes the following steps: [The chemical structure is described in the original text]. Diphenylmethane di(ureidoimidazoleacetic acid) monomer and trimethylolpropane were added to N,N-dimethylformamide, heated to 130-145℃, p-toluenesulfonic acid was added under a nitrogen atmosphere, the reaction was carried out for 3-5 hours, cooled to 110-125℃, alkyl bromide compound was added, the reaction was continued for 48-96 hours, cooled to room temperature, the solution was poured into methanol to precipitate, filtered, washed, and hyperbranched polyquaternary ammonium salt was obtained. The mass of the citric acid is (70-200)% of the mass of the isocyanate graphene. The molar amounts of the trimethylolpropane and alkyl bromide compound are (62-70)% and (210-260)% of the molar amounts of the diphenylmethane di(ureidoimidazole acetic acid) monomer; the molecular formula of the alkyl bromide compound is C2. n H 2n+1 Br and n are any integers from 10 to 18; The mass ratio of graphene oxide to 4,4-diphenylmethane diisocyanate is 0.5:

1.

2. The high-modulus film masterbatch according to claim 1, characterized in that, The reaction solvents include N,N-dimethylformamide, tetrahydrofuran, and 1,4-dioxane.

3. The high-modulus film masterbatch according to claim 1, characterized in that, The production process of the diphenylmethane di(ureidoimidazolium acetic acid) monomer includes the following steps: (1) Add 3-chloro-L-alanine and 4,4-diphenylmethane diisocyanate to the solvent, heat to 60-80℃, react for 3-5 h, concentrate under reduced pressure, wash, and obtain diphenylmethane di(ureochloroacetic acid) intermediate; (2) Add diphenylmethane di(ureachloroacetic acid) intermediate, imidazole and potassium carbonate to acetonitrile, heat to 65-80℃, react for 3-8h, concentrate under reduced pressure, wash and recrystallize to obtain diphenylmethane di(ureaimidazoleacetic acid) monomer.

4. The high-modulus film masterbatch according to claim 3, characterized in that, The solvent in (1) includes tetrahydrofuran and 1,4-dioxane.

5. The high-modulus film masterbatch according to claim 3, characterized in that, The molar amount of 3-chloro-L-alanine in (1) is (200-230) of the molar amount of 4,4-diphenylmethane diisocyanate.

6. The high-modulus film masterbatch according to claim 3, characterized in that, In (2), the molar amounts of imidazole and potassium carbonate are (210-250)% and (320-420)% of the molar amounts of diphenylmethane di(ureochloroacetic acid) intermediate, respectively.

7. A production process for a high-modulus film masterbatch as described in any one of claims 1-6, characterized in that, The process includes the following steps: adding 100 parts by weight of polypropylene resin, 0.5-3 parts by weight of functionalized graphene, 2-8 parts by weight of hyperbranched polyquaternary ammonium salt, and 0.2-0.6 parts by weight of antioxidant into a twin-screw extruder for co-extrusion, with a five-stage temperature of 175-190℃, followed by granulation to obtain a high-modulus film masterbatch.

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