Preparation method of modified PET (Polyethylene Terephthalate) film material

Abstract

The invention relates to the technical field of polyethylene glycol terephthalate, and discloses a preparation method of a modified PET film material, which comprises the following steps: extruding 100 parts by weight of hyperbranched polyester quaternary ammonium salt, 0.5-3 parts by weight of polyethylene glycol terephthalate and the like, granulating, and carrying out film blowing molding to obtain the modified PET film material. The hyperbranched polyester quaternary ammonium salt provided by the invention contains a polyester structural unit, has good compatibility with PET polyester, has a hyperbranched three-dimensional dendritic network structure, can play a good toughening role, and is beneficial to improving the tensile strength and elongation at break of a PET film material. The antibacterial agent contains better quaternary ammonium salt antibacterial sites and is uniformly dispersed in a PET polyester film matrix, so that the antibacterial property of a film material is improved.

Description

Technical Field

[0001] The invention relates to the technical field of polyethylene terephthalate, in particular to a method for preparing a modified PET film material. Background Art

[0002] PET polyethylene terephthalate has good film-forming properties and can be made into excellent film materials through methods such as blow molding, multi-layer co-extrusion, and casting. It is widely used in printing, vacuum aluminum-plated products, traffic reflective signs, food and drug packaging, and other fields. Modifying PET film materials to give them better antibacterial properties, heat resistance, mechanical properties, etc. is a research hotspot. Hyperbranched polymers are three-dimensional macromolecular polymers with many branching points and molecular chains that are not easily entangled. They can be used as processing aids, crystallization aids, toughening agents, etc. for polymer materials and are widely used. The patent with the authorization announcement number CN115073735B discloses a hyperbranched semi-aromatic polyester imide polymer and a preparation method thereof. Aromatic polycarboxylic acids / polyanhydrides, monoamino polyols, monoamino monoalcohols, etc. are used as raw materials. Through molten polyester and imidization reaction, the hyperbranched polyester imide obtained can improve the crystallization temperature and crystallinity of PET. However, the mechanical properties, antibacterial properties, and heat resistance of the products prepared by the patent are poor. Summary of the invention

[0003] In view of the deficiencies of the prior art, the present invention provides a method for preparing a modified PET film material with heat resistance and antibacterial properties.

[0004] The preparation method of the modified PET film material comprises the following steps: S1. Add ethanol to the reaction vessel, and the molar ratio of intermediate 1 and intermediate 2 is (1.4-1.6):1, heat to 75-85°C, react for 24-36 hours, filter, wash the precipitate with ethanol, and dry to obtain a hyperbranched polyester quaternary ammonium salt. The reaction formula is as follows: ; S2, 100 parts by weight of polyethylene terephthalate, 0.5-3 parts by weight of hyperbranched polyester quaternary ammonium salt, and 0.3-0.5 parts by weight of antioxidant are mixed, added into a twin-screw extruder, extruded, granulated, and then the pellets are blown into film by an extrusion film blowing machine to obtain a modified PET film material.

[0005] Furthermore, the preparation method of the intermediate 1 is as follows: tetrahydrofuran and water in a volume ratio of 1: (0.3-0.4) are added to a reaction container, 1,3-dichloro-2-propanol and sodium hydroxide are added, 2-chloro-4,6-diphenyl-1,3,5-triazine is added after stirring, the mixture is heated to 65-70°C, condensed and refluxed for 4-7 hours, hydrochloric acid solution is added dropwise for neutralization after cooling, tetrahydrofuran is removed by vacuum distillation, a precipitate is precipitated by heating, and then the mixture is cooled in an ice-water bath and recrystallized to obtain the intermediate 1. The reaction formula is as follows: .

[0006] Furthermore, the molar ratio of the 1,3-dichloro-2-propanol, sodium hydroxide, and 2-chloro-4,6-diphenyl-1,3,5-triazine is 1:(1-1.2):(1-1.1).

[0007] Furthermore, the preparation method of the intermediate 2 is as follows: toluene, trimethylolpropane, N,N-dimethylglycine, and p-toluenesulfonic acid in a molar ratio of 1: (3-3.9): (0.24-0.33) are added to a reaction container, heated to 90-100°C, reacted for 12-18h, concentrated under reduced pressure to remove low boiling points, washed with petroleum ether, and dried to obtain the intermediate 2. The reaction formula is as follows: .

[0008] Furthermore, the temperature of each section of the extruder in S2 is 215-265°C; the temperature of each section of the extrusion film blowing machine is 275-290°C, the blow-up ratio is 2.5-3.5, and the pulling speed is 4-7m / min.

[0009] Beneficial effects: The present invention utilizes an intermediate 1 containing a diphenyltriazine structure and an intermediate 2 containing multiple ester groups to carry out a quaternization polymerization reaction to obtain a hyperbranched polyester quaternary ammonium salt, which is then melt-mixed with polyethylene terephthalate and blown into a film to obtain a modified PET film material. The hyperbranched polyester quaternary ammonium salt contains a polyester structural unit, has good compatibility with PET polyester, and has a hyperbranched three-dimensional dendritic network structure, forms a chain entanglement effect with a PET molecular chain, forms a physical cross-linking site, plays a good toughening role, is conducive to improving the mechanical properties of the PET film material, and exhibits higher tensile strength and elongation at break.

[0010] The hyperbranched polyester quaternary ammonium salt contains a heat-resistant diphenyltriazine structure and has good thermal decomposition resistance. When added to PET, it is beneficial to improve the initial thermal decomposition temperature and heat resistance of the PET film material.

[0011] The hyperbranched polyester quaternary ammonium salt of the invention contains a three-dimensional dendritic network structure, has more quaternary ammonium salt antibacterial sites, and contains a polyester structure, has better compatibility with PET polyester, can be uniformly dispersed in a PET polyester film matrix, and is beneficial to improving the antibacterial performance of the film material. DETAILED DESCRIPTION

[0012] In order to better understand the present invention, the present invention is further explained below in conjunction with the embodiments, but the present invention is not limited to the following embodiments.

[0013] Embodiment 1: The preparation method of the modified PET film material comprises the following steps: (1) Add 20 mL of tetrahydrofuran, 6 mL of water, 6 mmol of 1,3-dichloro-2-propanol, and 6 mmol of sodium hydroxide to a reaction vessel, stir, add 6 mmol of 2-chloro-4,6-diphenyl-1,3,5-triazine, heat to 70°C, condense and reflux for 4 h, cool, add hydrochloric acid solution dropwise to neutralize, remove tetrahydrofuran by vacuum distillation, heat to volatilize and precipitate, then cool in an ice-water bath and recrystallize to obtain intermediate 1; (2) Add 15 ml of toluene, 4 mmol of trimethylolpropane, 12 mmol of N,N-dimethylglycine, and 1.32 mmol of p-toluenesulfonic acid to a reaction vessel, heat to 90°C, react for 12 h, concentrate under reduced pressure to remove low-boiling substances, wash with petroleum ether, and dry to obtain intermediate 2; (3) Add 50 mL of ethanol, 15 mmol of intermediate 1 and 10 mmol of intermediate 2 to a reaction vessel, heat to 75° C., react for 36 h, filter, wash the precipitate with ethanol, and dry to obtain a hyperbranched polyester quaternary ammonium salt; (4) 100 g of polyethylene terephthalate, 0.5 g of hyperbranched polyester quaternary ammonium salt, and 0.3 g of antioxidant 168 were mixed and added to a twin-screw extruder for extrusion and granulation. The temperatures of each section of the twin-screw extruder were 215°C, 230°C, 250°C, 265°C, and 260°C. The pellets were then blown into film by an extrusion film blowing machine. The temperatures of each section were 275°C, 280°C, 290°C, 290°C, and 285°C. The blowing ratio was 3 and the pulling speed was 4 m / min to obtain a modified PET film material.

[0014] Embodiment 2: The preparation method of the modified PET film material comprises the following steps: (1) Add 20 mL of tetrahydrofuran, 8 mL of water, 6 mmol of 1,3-dichloro-2-propanol, and 7.2 mmol of sodium hydroxide to a reaction vessel, stir, add 6.6 mmol of 2-chloro-4,6-diphenyl-1,3,5-triazine, heat to 65°C, condense and reflux for 7 h, cool, dropwise add hydrochloric acid solution to neutralize, remove tetrahydrofuran by vacuum distillation, heat to volatilize and precipitate, then cool in an ice-water bath and recrystallize to obtain intermediate 1; (2) Add 15 ml of toluene, 4 mmol of trimethylolpropane, 15.6 mmol of N,N-dimethylglycine, and 0.96 mmol of p-toluenesulfonic acid to a reaction vessel, heat to 100°C, react for 18 hours, concentrate under reduced pressure to remove low-boiling substances, wash with petroleum ether, and dry to obtain intermediate 2; (3) Add 60 mL of ethanol, 14 mmol of intermediate 1 and 10 mmol of intermediate 2 to the reaction container, heat to 85 °C, react for 24 h, filter, wash the precipitate with ethanol, and dry to obtain a hyperbranched polyester quaternary ammonium salt; (4) 100 g of polyethylene terephthalate, 1 g of hyperbranched polyester quaternary ammonium salt, and 0.5 g of antioxidant 168 were mixed and added to a twin-screw extruder for extrusion and granulation. The temperatures of each section of the twin-screw extruder were 215°C, 230°C, 250°C, 265°C, and 260°C. The pellets were then blown into film by an extrusion film blowing machine. The temperatures of each section were 275°C, 280°C, 290°C, 290°C, and 285°C. The blowing ratio was 3.5 and the pulling speed was 7 m / min to obtain a modified PET film material.

[0015] Embodiment 3: The preparation method of the modified PET film material comprises the following steps: (1) Add 80 mL of ethanol, 16 mmol of intermediate 1 (prepared in Example 1) and 10 mmol of intermediate 2 (prepared in Example 1) into a reaction container, heat to 80° C., react for 24 h, filter, wash the precipitate with ethanol, and dry to obtain a hyperbranched polyester quaternary ammonium salt; (2) 100 g of polyethylene terephthalate, 2 g of hyperbranched polyester quaternary ammonium salt, and 0.3 g of antioxidant 168 were mixed and added to a twin-screw extruder for extrusion and granulation. The temperatures of each section of the twin-screw extruder were 215°C, 230°C, 250°C, 265°C, and 260°C. The pellets were then blown into film by an extrusion film blowing machine. The temperatures of each section were 275°C, 280°C, 290°C, 290°C, and 285°C. The blowing ratio was 2.5. The pulling speed was 5 m / min. A modified PET film material was obtained.

[0016] Embodiment 4: The preparation method of the modified PET film material comprises the following steps: (1) Add 60 mL of ethanol, 15 mmol of intermediate 1 (prepared in Example 1) and 10 mmol of intermediate 2 (prepared in Example 1) into a reaction container, heat to 85° C., react for 24 h, filter, wash the precipitate with ethanol, and dry to obtain a hyperbranched polyester quaternary ammonium salt; (2) 100 g of polyethylene terephthalate, 3 g of hyperbranched polyester quaternary ammonium salt, and 0.3 g of antioxidant 168 were mixed and added to a twin-screw extruder for extrusion and granulation. The temperatures of each section of the twin-screw extruder were 215°C, 230°C, 250°C, 265°C, and 260°C. The pellets were then blown into film by an extrusion film blowing machine. The temperatures of each section were 275°C, 280°C, 290°C, 290°C, and 285°C. The blowing ratio was 3 and the pulling speed was 4 m / min to obtain a modified PET film material.

[0017] Comparative Example 1: A method for preparing a PET film material comprises the following steps: (1) 100 g of polyethylene terephthalate and 0.3 g of antioxidant 168 were mixed and added into a twin-screw extruder for extrusion and granulation. The temperatures of each section of the twin-screw extruder were 215°C, 230°C, 250°C, 265°C and 260°C. The pellets were then blown into film by an extrusion film blowing machine. The temperatures of each section were 275°C, 280°C, 290°C, 290°C and 285°C. The blowing ratio was 3 and the pulling speed was 4 m / min to obtain a PET film material.

[0018] Comparative Example 2: A method for preparing a modified PET film material comprises the following steps: (1) Add 50 mL of ethanol, 10 mmol of intermediate 1 and 10 mmol of N,N,N',N'-tetramethylethylenediamine to a reaction vessel, heat to 75°C, react for 36 hours, filter, wash the precipitate with ethanol, and dry to obtain a polyquaternary ammonium salt; (2) 100 g of polyethylene terephthalate, 0.5 g of polyquaternium salt, and 0.3 g of antioxidant 168 were mixed and added to a twin-screw extruder for extrusion and granulation. The temperatures of each section of the twin-screw extruder were 215°C, 230°C, 250°C, 265°C, and 260°C. The pellets were then blown into film by an extrusion film blowing machine. The temperatures of each section were 275°C, 280°C, 290°C, 290°C, and 285°C. The blowing ratio was 3 and the pulling speed was 4 m / min to obtain a modified PET film material.

[0019] Comparative Example 3: A method for preparing a modified PET film material, comprising the following steps: (1) Add 50 mL of ethanol, 15 mmol of 1,3-dichloropropane and 10 mmol of intermediate 2 to a reaction vessel, heat to 75°C, react for 36 hours, filter, wash the precipitate with ethanol, and dry to obtain a polyester quaternary ammonium salt; (2) 100 g of polyethylene terephthalate, 0.5 g of hyperbranched polyester quaternary ammonium salt, and 0.3 g of antioxidant 168 were mixed and added to a twin-screw extruder for extrusion and granulation. The temperatures of each section of the twin-screw extruder were 215°C, 230°C, 250°C, 265°C, and 260°C. The pellets were then blown into film by an extrusion film blowing machine. The temperatures of each section were 275°C, 280°C, 290°C, 290°C, and 285°C. The blowing ratio was 3 and the pulling speed was 4 m / min to obtain a modified PET film material.

[0020] The tensile properties of PET film materials were tested according to GB / T 1040.3-2006 method.

[0021] Escherichia coli and Staphylococcus aureus were used as test bacteria, cultured, activated and diluted into bacterial suspension (concentration of 10 6 cfu / mL). Drop 0.2mL of bacterial suspension on the surface of PET film material, and then cover the surface of PET film material with polyethylene film. Incubate at 37℃ for 24h, wash the PET film material and polyethylene film with 20mL of 0.8% sodium chloride solution, take 0.1mL of solution and drop it on nutrient agar medium, incubate at 37℃ for 48h, and count the viable bacteria.

[0022] Calculate the inhibition rate R. R = (AB) / A × 100%.

[0023] A is the average number of recovered bacteria (cfu / piece) in the blank control group (PET film material prepared in Comparative Example 1). B is the average number of recovered bacteria (cfu / piece) in the antibacterial sample group.

[0024] The PET film material was subjected to thermogravimetric analysis using a thermogravimetric analyzer in a nitrogen atmosphere with a heating rate of 10°C / min and a test temperature of 25-800°C.

[0025] Table 1: Test results of PET film materials prepared in various embodiments and comparative examples

[0026] Compared with Comparative Example 1, Examples 1 to 4 add hyperbranched polyester quaternary ammonium salts, contain polyester structural units, have good compatibility with PET polyester, and have a hyperbranched three-dimensional dendritic network structure, which forms a chain entanglement with the PET molecular chain, forms a physical cross-linking site, plays a good toughening role, is conducive to improving the mechanical properties of the PET film material, and shows higher tensile strength and elongation at break. In addition, the hyperbranched polyester quaternary ammonium salt contains a heat-resistant diphenyl triazine structure ( ), has good resistance to thermal decomposition. Adding it to PET is beneficial to improving the initial thermal decomposition temperature (temperature at 5% thermal weight loss) and heat resistance of PET film materials.

[0027] Comparative Example 2: N,N,N,N-tetramethylethylenediamine is reacted with intermediate 1 to obtain a polyquaternary ammonium salt that is a linear molecular chain. It does not have a hyperbranched three-dimensional dendritic network structure and does not contain a polyester structure. It has poor compatibility with PET polyester and a poor toughening effect. The tensile strength and elongation at break of the film material are low.

[0028] In Comparative Example 3, 1,3-dichloropropane and Intermediate 2 were reacted to obtain a hyperbranched polyester quaternary ammonium salt without a heat-resistant diphenyltriazine structure, resulting in a lower initial thermal decomposition temperature of the PET film material and poor heat resistance.

[0029] Table 2: Test results of antibacterial properties of PET film materials prepared in various embodiments and comparative examples

[0030] After testing, compared with the linear polyquaternary ammonium salt prepared in Comparative Example 2, the antibacterial properties of the hyperbranched polyester quaternary ammonium salts prepared in Examples 1 to 4 and Comparative Example 3 are better, and the obtained modified PET film material has a higher inhibition rate against bacteria such as Escherichia coli. This is mainly because the hyperbranched polyester quaternary ammonium salt contains a three-dimensional dendritic network structure, the quaternary ammonium salt has more antibacterial sites, and it contains a polyester structure, has better compatibility with PET polyester, can be evenly dispersed in the PET polyester film matrix, and is conducive to improving the antibacterial properties of the film material.

[0031] The above is only a preferred embodiment of the present invention, and does not limit the present invention in any form. Although the present invention has been disclosed as a preferred embodiment, it is not used to limit the present invention. Any technician familiar with this patent can make some changes or modify the technical contents suggested above into equivalent embodiments without departing from the scope of the technical solution of the present invention. However, any simple modification, equivalent change and modification made to the above embodiments according to the technical essence of the present invention without departing from the content of the technical solution of the present invention still fall within the scope of the solution of the present invention.

Claims

1. A method for preparing a modified PET film material, characterized in that: The steps include: S1. Add ethanol to the reaction vessel, the structural formula is The intermediate 1 has the structural formula The intermediate 2 is heated to 75-85°C, reacted for 24-36 hours, filtered, washed with ethanol, and dried to obtain a hyperbranched polyester quaternary ammonium salt; S2, 100 parts by weight of polyethylene terephthalate, 0.5-3 parts by weight of hyperbranched polyester quaternary ammonium salt, and 0.3-0.5 parts by weight of antioxidant are mixed, added into a twin-screw extruder, extruded, granulated, and then the pellets are blown into film by an extrusion film blowing machine to obtain a modified PET film material.

2. The method for preparing the modified PET film material according to claim 1, characterized in that: The molar ratio of the intermediate 1 to the intermediate 2 is (1.4-1.6):

1.

3. The method for preparing the modified PET film material according to claim 2, characterized in that: The preparation method of the intermediate 1 is as follows: tetrahydrofuran, water, 1,3-dichloro-2-propanol, and sodium hydroxide are added into a reaction container, 2-chloro-4,6-diphenyl-1,3,5-triazine is added after stirring, the mixture is heated to 65-70° C., condensed and refluxed for reaction for 4-7 hours, hydrochloric acid solution is added dropwise for neutralization after cooling, tetrahydrofuran is removed by vacuum distillation, a precipitate is precipitated by heating, and then the mixture is cooled in an ice-water bath and recrystallized to obtain the intermediate 1.

4. The method for preparing the modified PET film material according to claim 3, characterized in that: The molar ratio of the 1,3-dichloro-2-propanol, sodium hydroxide and 2-chloro-4,6-diphenyl-1,3,5-triazine is 1:(1-1.2):(1-1.1).

5. The method for preparing the modified PET film material according to claim 3, characterized in that: The volume ratio of tetrahydrofuran to water is 1:(0.3-0.4).

6. The method for preparing the modified PET film material according to claim 2, characterized in that: The preparation method of the intermediate 2 is as follows: toluene, trimethylolpropane, N,N-dimethylglycine, and p-toluenesulfonic acid are added to a reaction container, heated to 90-100° C., reacted for 12-18 hours, concentrated under reduced pressure to remove low boiling points, washed with petroleum ether, and dried to obtain the intermediate 2.

7. The method for preparing the modified PET film material according to claim 6, characterized in that: The molar ratio of trimethylolpropane, N,N-dimethylglycine and p-toluenesulfonic acid is 1:(3-3.9):(0.24-0.33).

8. The method for preparing the modified PET film material according to claim 1, characterized in that: The temperature of each section of the extruder in S2 is 215-265° C.; the temperature of each section of the extrusion film blowing machine is 275-290° C., the blow-up ratio is 2.5-3.5, and the traction speed is 4-7 m / min.

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