Polyethylene filter membrane for homogenizing bag and preparation method thereof

Abstract

The present invention discloses a polyethylene filter membrane for homogenizing bags and a preparation method thereof, relating to the field of new materials technology. The polyethylene filter membrane for homogenizing bags produced in the present invention is made by attaching a modified phospholipid to a composite polyethylene filter membrane. The composite polyethylene filter membrane is formed by laminating an irradiated polyethylene filter membrane with a thiol chitosan membrane, thereby enhancing the mechanical properties of the filter membrane. The modified phospholipid is obtained by first epoxidizing soybean phospholipid and then reacting it with a terpolymer through a ring-opening reaction. The terpolymer is obtained by introducing hydroxyl-terminated polybutadiene to both ends of polyvinyl alcohol. The epoxy rings on the epoxidized soybean phospholipid can undergo a ring-opening reaction with the terpolymer, introducing both hydroxyl groups and amphiphilic long chains of the terpolymer, thereby improving the hydrophilicity of the filter membrane and enhancing its stability.

Description

Technical Field

[0001] The present invention relates to the technical field of new materials, in particular to a polyethylene filter membrane for homogeneous bags and a preparation method thereof. Background Art

[0002] Homogenizing bags are primarily used for sample processing, pre-enrichment, or sample dilution during food testing for various bacterial species. These bags include full-membrane, side-membrane, and membraneless homogenizing bags. Homogenizing bags are available with either non-woven or polyethylene membranes. Polyethylene membranes, due to their low surface energy, poor hydrophilicity, and poor biocompatibility, are prone to protein adhesion, making them difficult to clean.

[0003] Polyethylene membrane is a non-polar material with low surface energy, inert and hydrophobic surface, and is not easy to be compounded or mixed with other materials, which limits the further application of polyethylene. Without affecting the performance of the polyethylene itself, surface modification is carried out within the nanometer range. Therefore, the present invention connects modified phospholipids to the surface of the polyethylene filter membrane to study and prepare a high-strength, highly hydrophilic polyethylene filter membrane for homogeneous bags. Summary of the Invention

[0004] The object of the present invention is to provide a polyethylene filter membrane for homogeneous bags and a preparation method thereof, so as to solve the problems raised in the above background technology.

[0005] In order to solve the above technical problems, the present invention provides the following technical solutions: a polyethylene filter membrane for a homogenizing bag, wherein the polyethylene filter membrane for a homogenizing bag is prepared by connecting a modified phospholipid to a composite polyethylene filter membrane.

[0006] Preferably, the composite polyethylene filter membrane is made by laminating an irradiated polyethylene filter membrane and a mercapto chitosan membrane; the mercapto chitosan membrane is made by reacting chitosan with thioglycolic acid after casting the chitosan membrane.

[0007] Preferably, the modified lecithin is prepared by ring-opening reaction of epoxy soybean lecithin and terpolymer.

[0008] Preferably, the terpolymer is prepared by introducing terminal hydroxyl polybutadiene into both ends of polyethylene glycol p-toluenesulfonate.

[0009] Preferably, a method for preparing a polyethylene filter membrane for a homogeneous bag comprises the following specific steps:

[0010] (1) thioglycolic acid and concentrated sulfuric acid (mass fraction: 20-30%) are mixed in a mass ratio of 80-100:1 to prepare a thioglycolic acid solution; a chitosan membrane is immersed in the thioglycolic acid solution for 18-24 hours, the thioglycolic acid solution on the surface is absorbed with filter paper, and then dried to prepare a thiolated chitosan membrane;

[0011] (2) laying a thiol chitosan membrane, an irradiated polyethylene filter membrane, and a thiol chitosan membrane in sequence, placing the membrane in a hot press, and hot pressing the membrane at 120 to 140° C. for 2 to 4 minutes to obtain a composite polyethylene filter membrane;

[0012] (3) Mixing hydroxyl-terminated polybutadiene, triethylamine, and tetrahydrofuran in a mass ratio of 1-1.2:0.7:4.5-5, placing in an ice bath, adding polyethylene glycol p-toluenesulfonate in an amount 2-2.2 times the mass of the hydroxyl-terminated polybutadiene, reacting for 30-50 minutes, heating to 40-50 minutes, and continuing the reaction for 24-28 hours, filtering, precipitating with methanol, and rotary evaporating to obtain a terpolymer;

[0013] (4) Epoxidized soybean lecithin, terpolymer, and potassium hydroxide were mixed in a mass ratio of 1:1.2-1.5:0.1-0.3, stirred at 200-400 rpm, heated to 80-90°C, reacted for 3-5 hours, then cooled to 40-50°C, and anhydrous sodium bicarbonate in an amount of 0.3-0.5 times the mass of epoxidized soybean lecithin was added, and the reaction was continued for 2-6 hours to obtain modified lecithin;

[0014] (5) The composite polyethylene filter membrane is mixed with the modified phospholipid, heated to 60-80°C, triethylamine is added, reacted for 6-8 hours, removed and rinsed with deionized water for 5-8 minutes, and dried to obtain a polyethylene filter membrane for a homogeneous bag.

[0015] Preferably, in the above step (1): the preparation method of the chitosan film is: chitosan and acetic acid solution with a mass fraction of 1-2% are mixed in a mass ratio of 6-7:25, stirred at room temperature and 200-400 rpm for 8-12 hours, ultrasonic degassing at 50-80 kHz for 20-30 minutes, vacuum degassing for 3-5 minutes, and finally casting the film on a polytetrafluoroethylene plate, and then transferring it to a sodium hydroxide solution with a mass fraction of 3-6% and soaking it for 2-4 hours. After being removed, rinsed with distilled water and dried to obtain a chitosan film with a thickness of 0.08-0.18 mm.

[0016] Preferably, in the above step (2), the process of irradiating the polyethylene filter membrane is as follows: placing the polyethylene membrane in an irradiation tube to 60 The Co source is irradiated at room temperature for 3 to 5 minutes.

[0017] Preferably, in the above step (3), the preparation method of polyethylene glycol p-toluenesulfonate is: polyethylene glycol, p-toluenesulfonyl chloride, dichloromethane and pyridine are mixed in a mass ratio of 4:1 to 1.2:20:10, stirred evenly and reacted at room temperature for 20 to 24 hours, extracted 3 to 5 times with 3 to 5 mol / L hydrochloric acid, centrifuged, and freeze-dried at -60 to -80°C for 36 to 48 hours, then placed in tetrahydrofuran with a mass of 8 to 12 times that of polyethylene glycol, ultrasonically dissolved at 60 to 80 kHz, and then added with ether with a mass of 2 to 3 times that of tetrahydrofuran, frozen at -40 to -60°C for 20 to 30 minutes, filtered and vacuum dried to obtain polyethylene glycol p-toluenesulfonate.

[0018] Preferably, in the above step (4), the preparation method of epoxidized soybean lecithin is as follows: soybean lecithin, catalyst acidic cation exchange resin and glacial acetic acid are mixed in a mass ratio of 8-10:0.8-0.9:1, stirred and heated to 62-66°C at 50-100rpm, and hydrogen peroxide 0.5-0.6 times the mass of soybean lecithin is added dropwise at a rate of 3-5ml / min. After the addition is completed, the mixture is reacted for 5-8h, cooled to 40-45°C, and the pH is adjusted to 6.8-7.2 with sodium hydroxide. The reaction is continued for 15-30min, and then washed with saturated sodium chloride solution and deionized water for 3-5 times in sequence, and finally distilled under reduced pressure to obtain epoxidized soybean lecithin.

[0019] Preferably, in the above step (5), the mass ratio of the composite polyethylene filter membrane, the modified phospholipid and the triethylamine is 1:8-15:0.2-0.4.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] The polyethylene filter membrane for homogenizing bags prepared by the present invention is prepared by connecting modified phospholipids to a composite polyethylene filter membrane;

[0022] The composite polyethylene filter membrane is made by laminating an irradiated polyethylene filter membrane with a mercapto chitosan membrane. The mercapto chitosan membrane is made by reacting chitosan with thioglycolic acid after casting. The amino groups on the chitosan react with the carboxyl groups on the thioglycolic acid to introduce thiols into the chitosan. The irradiated polyethylene filter membrane and the mercapto chitosan membrane are then laminated together to enhance the mechanical properties of the filter membrane.

[0023] Modified lecithin is prepared by first epoxidizing soybean lecithin and then reacting it with a terpolymer to form a ring-opening reaction; the terpolymer is prepared by introducing terminal hydroxyl polybutadiene into both ends of polyvinyl alcohol; polyethylene glycol undergoes esterification with p-toluenesulfonyl chloride to form polyethylene glycol p-toluenesulfonate, which then reacts with the end group on the terminal hydroxyl polybutadiene to form a terpolymer with a terminal hydroxyl polybutadiene-polyvinyl alcohol-hydroxyl polybutadiene structure; the epoxy ring on the epoxidized soybean lecithin has strong tension and active chemical properties, and can react with the terpolymer to form a terpolymer with a terminal hydroxyl polybutadiene-polyvinyl alcohol-hydroxyl polybutadiene structure. The ring-opening reaction introduces hydroxyl groups and a long chain of amphiphilic ternary copolymer, so that in the process of preparing the modified phospholipid, the polar ends of the molecules are close to each other and the non-polar ends are close to each other, forming a special-shaped modified phospholipid. After being connected to the surface of the composite polyethylene filter membrane, the roughness of the filter membrane surface is enhanced and the hydrophilicity is improved; the double bonds on the modified phospholipid can also react with the thiol groups on the composite polyethylene filter membrane, tightly connecting the modified phospholipid to the surface of the composite polyethylene filter membrane, thereby enhancing the stability of the filter membrane. DETAILED DESCRIPTION

[0024] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with 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 making creative work are within the scope of protection of the present invention. Chitosan in the embodiments of the present invention and the comparative examples was purchased from Dalian Meilun Biotechnology Co., Ltd.; polyethylene membrane was purchased from Guangzhou Filter Source Water Purification Equipment Co., Ltd.; polyethylene glycol was purchased from Dalian Meilun Biotechnology Co., Ltd.; soybean lecithin was purchased from Guangzhou Yide Lecithin Technology Co., Ltd.; catalyst acidic cation exchange resin was purchased from Shanghai Kaiyin Chemical Co., Ltd.

[0025] In order to more clearly illustrate the method provided by the present invention, the following examples are used to describe in detail the various index testing methods of the polyethylene filter membranes for homogeneous bags prepared in the examples and comparative examples as follows:

[0026] Hydrophilicity: The contact angles of the homogeneous bags prepared in the embodiment and the comparative example of the same size were measured using a polyethylene filter membrane using a contact angle meter.

[0027] Mechanical properties: The polyethylene filter membranes for homogeneous bags prepared in the embodiment and comparative example of the same size were subjected to breaking tensile strain and tensile strength tests according to GB / T1040.

[0028] Stability: After the polyethylene filter membranes of the homogeneous bags prepared in the embodiment and the comparative example of the same size were used to the same extent, the contact angles were measured again using a contact angle meter.

[0029] Example 1

[0030] (1) Chitosan was mixed with 1-2% acetic acid solution in a mass ratio of 6:25, stirred at room temperature and 200 rpm for 8 h, ultrasonically degassed at 50 kHz for 20 min, and vacuum degassed for 3 min. Finally, a film was cast on a polytetrafluoroethylene plate, and then transferred to a 3% sodium hydroxide solution and soaked for 2 h. After being removed, it was rinsed with distilled water and dried to obtain a chitosan film with a thickness of 0.08 mm. Thioglycolic acid and 20% concentrated sulfuric acid were mixed in a mass ratio of 80:1 to obtain a thioglycolic acid solution. The chitosan film was immersed in the thioglycolic acid solution for 18 h, the surface thioglycolic acid solution was absorbed with filter paper, and then dried to obtain a thioglycolic chitosan film.

[0031] (2) Place the polyethylene film in the irradiation tube to 60 The irradiation treatment was performed with a Co source at room temperature for 3 minutes to prepare an irradiated polyethylene filter membrane; a thiol chitosan membrane, an irradiated polyethylene filter membrane, and a thiol chitosan membrane were sequentially laid, placed in a hot press, and hot-pressed at 120°C for 2 minutes to prepare a composite polyethylene filter membrane;

[0032] (3) Polyethylene glycol, p-toluenesulfonyl chloride, dichloromethane and pyridine were mixed in a mass ratio of 4:1:20:10, stirred evenly and reacted at room temperature for 20 hours, extracted three times with 3 mol / L hydrochloric acid, centrifuged and freeze-dried at -60°C for 36 hours, then placed in tetrahydrofuran with a mass of 8 times that of polyethylene glycol, ultrasonically dissolved at 60 kHz, and then added with ether with a mass of 2 times that of tetrahydrofuran. The mixture was frozen at -40°C for 20 minutes, filtered and vacuum dried to obtain polyethylene glycol p-toluenesulfonate; hydroxy-terminated polybutadiene, triethylamine and tetrahydrofuran were mixed in a mass ratio of 1:0.7:4.5, placed in an ice bath, and polyethylene glycol p-toluenesulfonate with a mass of 2 times that of the hydroxy-terminated polybutadiene was added. The mixture was reacted for 30 minutes, heated to 40 minutes, and continued to react for 24 hours. The mixture was filtered and precipitated with methanol and rotary evaporated to obtain a terpolymer;

[0033] (4) Soybean lecithin, catalyst acidic cation exchange resin and glacial acetic acid were mixed in a mass ratio of 8:0.8:1, stirred at 50 rpm and heated to 62 ° C, and hydrogen peroxide 0.5 times the mass of soybean lecithin was added dropwise at a rate of 3 ml / min. After the addition was completed, the reaction was carried out for 5 hours, the temperature was lowered to 40 ° C, the pH was adjusted to 6.8 with sodium hydroxide, the reaction was continued for 15 minutes, and then washed with saturated sodium chloride solution and deionized water three times in sequence, and finally vacuum distilled to obtain epoxy soybean lecithin; epoxy soybean lecithin, terpolymer and potassium hydroxide were mixed in a mass ratio of 1:1.2:0.1, stirred at 200 rpm and heated to 80 ° C, reacted for 3 hours, and then cooled to 40 ° C, anhydrous sodium bicarbonate 0.3 times the mass of epoxy soybean lecithin was added, and the reaction was continued for 2 hours to obtain modified lecithin;

[0034] (5) The composite polyethylene filter membrane and the modified phospholipid were mixed, heated to 60°C, and triethylamine was added. The mass ratio of the composite polyethylene filter membrane, the modified phospholipid, and the triethylamine was 1:8:0.2. The mixture was reacted for 6 hours. The mixture was removed and rinsed with deionized water for 5 minutes, and dried to obtain a polyethylene filter membrane for a homogeneous bag.

[0035] Example 2

[0036] (1) Chitosan was mixed with 1.5% acetic acid solution in a mass ratio of 6.5:25, stirred at room temperature and 300 rpm for 10 h, ultrasonically degassed at 70 kHz for 25 min, and vacuum degassed for 4 min. Finally, a film was cast on a polytetrafluoroethylene plate, and then transferred to a 4.5% sodium hydroxide solution and soaked for 3 h. After being removed, it was rinsed with distilled water and dried to obtain a chitosan film with a thickness of 0.13 mm; thioglycolic acid and 20-30% concentrated sulfuric acid were mixed in a mass ratio of 90:1 to obtain a thioglycolic acid solution; the chitosan film was immersed in the thioglycolic acid solution for 21 h, the surface thioglycolic acid solution was absorbed with filter paper, and then dried to obtain a thioglycolic chitosan film;

[0037] (2) Place the polyethylene film in the irradiation tube to 60 The irradiation treatment was performed with a Co source at room temperature for 4 minutes to prepare an irradiated polyethylene filter membrane; a thiol chitosan membrane, an irradiated polyethylene filter membrane, and a thiol chitosan membrane were sequentially laid, placed in a hot press, and hot-pressed at 130°C for 3 minutes to prepare a composite polyethylene filter membrane;

[0038] (3) Polyethylene glycol, p-toluenesulfonyl chloride, dichloromethane and pyridine were mixed in a mass ratio of 4:1.1:20:10, stirred evenly and reacted at room temperature for 22 hours, extracted four times with 4 mol / L hydrochloric acid, centrifuged and freeze-dried at -70°C for 42 hours, then placed in tetrahydrofuran with a mass of 10 times that of polyethylene glycol, ultrasonically dissolved at 70 kHz, and then added with ether with a mass of 2.5 times that of tetrahydrofuran. The mixture was frozen at -50°C for 20-30 minutes, filtered and vacuum dried to obtain polyethylene glycol p-toluenesulfonate; hydroxy-terminated polybutadiene, triethylamine and tetrahydrofuran were mixed in a mass ratio of 1.1:0.7:4.8, placed in an ice bath, and polyethylene glycol p-toluenesulfonate with a mass of 2.1 times that of the hydroxy-terminated polybutadiene was added. The mixture was reacted for 40 minutes, heated to 45 minutes, and continued to react for 26 hours. The mixture was filtered and precipitated with methanol and rotary evaporated to obtain a terpolymer;

[0039] (4) Soybean lecithin, catalyst acidic cation exchange resin and glacial acetic acid were mixed in a mass ratio of 9:0.85:1, stirred and heated to 64°C at 80rpm, and hydrogen peroxide 0.55 times the mass of soybean lecithin was added dropwise at a rate of 4ml / min. After the addition was completed, the reaction was carried out for 6h, the temperature was lowered to 42°C, the pH was adjusted to 7.0 with sodium hydroxide, the reaction was continued for 25min, and then washed with saturated sodium chloride solution and deionized water 4 times in sequence, and finally vacuum distilled to obtain epoxy soybean lecithin; epoxy soybean lecithin, terpolymer and potassium hydroxide were mixed in a mass ratio of 1:1.35:0.2, stirred and heated to 85°C at 300rpm, reacted for 4h, cooled to 45°C, anhydrous sodium bicarbonate 0.4 times the mass of epoxy soybean lecithin was added, and the reaction was continued for 4h to obtain modified lecithin;

[0040] (5) The composite polyethylene filter membrane and the modified phospholipid were mixed, heated to 70°C, and triethylamine was added. The mass ratio of the composite polyethylene filter membrane, the modified phospholipid, and the triethylamine was 1:11:0.3. The mixture was reacted for 7 hours. The mixture was removed and rinsed with deionized water for 6 minutes, and dried to obtain a polyethylene filter membrane for a homogeneous bag.

[0041] Example 3

[0042] (1) Chitosan was mixed with 2% acetic acid solution in a mass ratio of 7:25, stirred at room temperature and 400 rpm for 12 h, ultrasonically degassed at 80 kHz for 30 min, and vacuum degassed for 5 min. Finally, a film was cast on a polytetrafluoroethylene plate, and then transferred to a 6% sodium hydroxide solution and soaked for 4 h. After being removed, it was rinsed with distilled water and dried to obtain a chitosan film with a thickness of 0.18 mm. Thioglycolic acid and 30% concentrated sulfuric acid were mixed in a mass ratio of 100:1 to obtain a thioglycolic acid solution. The chitosan film was immersed in the thioglycolic acid solution for 24 h, the surface thioglycolic acid solution was absorbed with filter paper, and then dried to obtain a thiolated chitosan film.

[0043] (2) Place the polyethylene film in the irradiation tube to 60 The irradiation treatment was performed with a Co source at room temperature for 5 minutes to prepare an irradiated polyethylene filter membrane; a thiol chitosan membrane, an irradiated polyethylene filter membrane, and a thiol chitosan membrane were sequentially laid, placed in a hot press, and hot-pressed at 140°C for 4 minutes to prepare a composite polyethylene filter membrane;

[0044] (3) Polyethylene glycol, p-toluenesulfonyl chloride, dichloromethane and pyridine were mixed in a mass ratio of 4:1.2:20:10, stirred evenly and reacted at room temperature for 24 hours, extracted 5 times with 5 mol / L hydrochloric acid, centrifuged and freeze-dried at -80°C for 48 hours, then placed in tetrahydrofuran with a mass of 12 times that of polyethylene glycol, ultrasonically dissolved at 80 kHz, and then added with ether with a mass of 3 times that of tetrahydrofuran. The mixture was frozen at -60°C for 30 minutes, filtered and vacuum-dried to obtain polyethylene glycol p-toluenesulfonate; hydroxy-terminated polybutadiene, triethylamine and tetrahydrofuran were mixed in a mass ratio of 1.2:0.7:5, placed in an ice bath, and polyethylene glycol p-toluenesulfonate with a mass of 2.2 times that of the hydroxy-terminated polybutadiene was added. The mixture was reacted for 50 minutes, heated to 50 minutes, and the reaction was continued for 28 hours. The mixture was filtered and precipitated with methanol and rotary evaporated to obtain a terpolymer;

[0045] (4) Soybean lecithin, catalyst acidic cation exchange resin and glacial acetic acid were mixed in a mass ratio of 10:0.9:1, stirred and heated to 66°C at 100 rpm, and hydrogen peroxide 0.6 times the mass of soybean lecithin was added dropwise at a rate of 5 ml / min. After the addition was completed, the mixture was reacted for 8 hours, cooled to 45°C, and the pH was adjusted to 7.2 with sodium hydroxide. The reaction was continued for 30 minutes, and then washed with saturated sodium chloride solution and deionized water 5 times in sequence. Finally, the mixture was distilled under reduced pressure to obtain epoxy soybean lecithin; epoxy soybean lecithin, terpolymer and potassium hydroxide were mixed in a mass ratio of 1:1.5:0.3, stirred and heated to 90°C at 400 rpm, reacted for 5 hours, cooled to 50°C, and anhydrous sodium bicarbonate 0.5 times the mass of epoxy soybean lecithin was added. The reaction was continued for 6 hours to obtain modified lecithin;

[0046] (5) The composite polyethylene filter membrane and the modified phospholipid were mixed, heated to 80°C, and triethylamine was added. The mass ratio of the composite polyethylene filter membrane, the modified phospholipid, and the triethylamine was 1:15:0.4. The mixture was reacted for 8 hours. The mixture was removed and rinsed with deionized water for 8 minutes, and dried to obtain a polyethylene filter membrane for a homogeneous bag.

[0047] Comparative Example 1

[0048] The formulation composition of Comparative Example 1 is the same as that of Example 2. The method for preparing the polyethylene filter membrane for homogenizing bags differs from that of Example 2 only in that the composite polyethylene filter membrane is not prepared, and the modified phospholipid is connected to the irradiated polyethylene filter membrane.

[0049] Comparative Example 2

[0050] The prescription composition of Comparative Example 2 is the same as that of Example 2. The only difference between the preparation method of the polyethylene filter membrane for homogeneous bags and Example 2 is that the preparation of step (3) is not performed, and step (4) is modified as follows: soybean lecithin, catalyst acidic cation exchange resin and glacial acetic acid are mixed in a mass ratio of 9:0.85:1, stirred and heated to 64°C at 80rpm, and hydrogen peroxide with a mass of 0.55 times that of soybean lecithin is added dropwise at a rate of 4ml / min. After the addition is completed, the reaction is carried out for 6h, the temperature is lowered to 42°C, the pH is adjusted to 7.0 with sodium hydroxide, the reaction is continued for 25min, and then washed 4 times with saturated sodium chloride solution and deionized water in sequence, and finally distilled under reduced pressure to obtain epoxidized soybean lecithin, which is the modified lecithin.

[0051] Comparative Example 3

[0052] The formulation composition of Comparative Example 3 is the same as that of Example 2. The method for preparing the polyethylene filter membrane for a homogeneous bag differs from that of Example 2 only in step (4), which is modified as follows: soybean lecithin, terpolymer, and potassium hydroxide are mixed in a mass ratio of 1:1.35:0.2, stirred at 300 rpm, heated to 85°C, reacted for 4 hours, cooled to 45°C, and anhydrous sodium bicarbonate in an amount 0.4 times the mass of soybean lecithin is added, and the reaction is continued for 4 hours to obtain a modified lecithin.

[0053] Comparative Example 4

[0054] (1) Chitosan was mixed with 1.5% acetic acid solution in a mass ratio of 6.5:25, stirred at room temperature and 300 rpm for 10 h, ultrasonically degassed at 70 kHz for 25 min, and vacuum degassed for 4 min. Finally, a film was cast on a polytetrafluoroethylene plate, and then transferred to a 4.5% sodium hydroxide solution and soaked for 3 h. After being removed, it was rinsed with distilled water and dried to obtain a chitosan film with a thickness of 0.13 mm; thioglycolic acid and 20-30% concentrated sulfuric acid were mixed in a mass ratio of 90:1 to obtain a thioglycolic acid solution; the chitosan film was immersed in the thioglycolic acid solution for 21 h, the surface thioglycolic acid solution was absorbed with filter paper, and then dried to obtain a thioglycolic chitosan film;

[0055] (2) Place the polyethylene film in the irradiation tube to 60 The Co source was irradiated at room temperature for 4 minutes to obtain an irradiated polyethylene filter membrane; the thiol chitosan membrane, the irradiated polyethylene filter membrane and the thiol chitosan membrane were laid in sequence, placed in a hot press, and hot pressed at 130°C for 3 minutes to obtain a polyethylene filter membrane for a homogeneous bag.

[0056] Effect Examples

[0057] Table 1 below shows the performance analysis results of the polyethylene filter membranes for homogeneous bags using Examples 1 to 3 of the present invention and Comparative Examples 1 to 4:

[0058] Table 1

[0059]

[0060] By comparing the experimental data of the examples and the comparative examples in Table 1, it can be clearly found that the polyethylene filter membranes for homogeneous bags prepared in Examples 1, 2 and 3 have better hydrophilicity, mechanical properties and stability.

[0061] From the comparison of the experimental data of Examples 1, 2, and 3 with Comparative Examples 1 and 4, it can be found that the thiol chitosan membrane prepared by introducing thiol groups into chitosan and reacting with thioglycolic acid after film casting is pressed with the irradiated polyethylene filter membrane to prepare the composite polyethylene filter membrane, has strong mechanical properties and can also react with the modified phospholipid to tightly connect the modified phospholipid to the surface of the composite polyethylene filter membrane;

[0062] From the comparison of the experimental data of Example 1, Example 2, Example 3 and Comparative Example 2, Comparative Example 3, Comparative Example 4, it can be found that the modified phospholipid prepared by epoxidizing soybean lecithin and then undergoing a ring-opening reaction with the terpolymer can be attached to the surface of the composite polyethylene filter membrane, thereby improving the hydrophilicity of the filter membrane.

[0063] From the comparison of the experimental data of Example 1, Example 2, Example 3 and Comparative Example 1, Comparative Example 2, Comparative Example 3, it can be found that the double bonds on the modified phospholipids can also react with the sulfhydryl groups on the composite polyethylene filter membrane, tightly connecting the modified phospholipids to the surface of the composite polyethylene filter membrane, thereby enhancing the stability of the filter membrane.

[0064] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above and that the invention can be embodied in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as illustrative and non-restrictive, and the scope of the invention is defined by the appended claims, not the foregoing description, and all variations within the meaning and range of equivalents of the claims are intended to be encompassed therein. Any reference in a claim should not be construed as limiting the claim to which it relates.

Claims

1. A method for preparing a polyethylene filter membrane for a homogeneous bag, characterized in that: The polyethylene filter membrane for the homogenizing bag is prepared by connecting a modified phospholipid to a composite polyethylene filter membrane; The preparation method of the polyethylene filter membrane for the homogenizing bag comprises the following specific steps: (1) Thioglycolic acid and concentrated sulfuric acid (mass fraction: 20-30%) were mixed at a mass ratio of 80-100:1 to prepare a thioglycolic acid solution; a chitosan membrane was immersed in the thioglycolic acid solution for 18-24 hours, the thioglycolic acid solution on the surface was absorbed with filter paper, and then dried to prepare a thiolated chitosan membrane; (2) Laying the thiol chitosan membrane, the irradiated polyethylene filter membrane and the thiol chitosan membrane in sequence, placing them in a hot press, and hot pressing them at 120-140°C for 2-4 minutes to obtain a composite polyethylene filter membrane; (3) Mix hydroxyl-terminated polybutadiene, triethylamine, and tetrahydrofuran in a mass ratio of 1-1.2:0.7:4.5-5, place in an ice bath, add polyethylene glycol p-toluenesulfonate (2-2.2 times the mass of hydroxyl-terminated polybutadiene), react for 30-50 minutes, heat to 40-50 minutes, continue to react for 24-28 hours, filter, precipitate with methanol, and rotary evaporate to obtain a terpolymer; (4) Epoxidized soybean lecithin, terpolymer and potassium hydroxide were mixed in a mass ratio of 1:1.2~1.5:0.1~0.3, stirred at 200~400 rpm and heated to 80~90°C. After reacting for 3~5 hours, the temperature was lowered to 40~50°C, and anhydrous sodium bicarbonate (0.3~0.5 times the mass of epoxidized soybean lecithin) was added. The reaction was continued for 2~6 hours to obtain modified lecithin. (5) Mix the composite polyethylene filter membrane with the modified phospholipid, heat it to 60-80°C, add triethylamine, react for 6-8 hours, remove it and rinse it with deionized water for 5-8 minutes, and dry it to obtain the polyethylene filter membrane for homogeneous bag.

2. The method for preparing a polyethylene filter membrane for a homogeneous bag according to claim 1, wherein: In the above step (1): the preparation method of the chitosan film is as follows: chitosan and 1-2% acetic acid solution are mixed in a mass ratio of 6-7:25, stirred at room temperature and 200-400 rpm for 8-12 hours, ultrasonically degassed at 50-80 kHz for 20-30 minutes, vacuum degassed for 3-5 minutes, and finally cast on a polytetrafluoroethylene plate. The film is then transferred to a 3-6% sodium hydroxide solution and soaked for 2-4 hours. After being removed, it is rinsed with distilled water and dried to obtain a chitosan film with a thickness of 0.08-0.18 mm.

3. The method for preparing a polyethylene filter membrane for a homogeneous bag according to claim 1, characterized in that: In the above step (2): the process of irradiating the polyethylene filter membrane is as follows: placing the polyethylene membrane in an irradiation tube to 60 The Co source was irradiated at room temperature for 3 to 5 minutes.

4. The method for preparing a polyethylene filter membrane for a homogeneous bag according to claim 1, wherein: In the above step (3): the preparation method of polyethylene glycol p-toluenesulfonate is as follows: polyethylene glycol, p-toluenesulfonyl chloride, dichloromethane and pyridine are mixed in a mass ratio of 4:1~1.2:20:10, stirred evenly and reacted at room temperature for 20~24 hours, extracted 3~5 times with 3~5 mol / L hydrochloric acid, centrifuged, and freeze-dried at -60~-80℃ for 36~48 hours, then placed in tetrahydrofuran with a mass of 8~12 times that of polyethylene glycol, ultrasonically dissolved at 60~80kHz, then added with ether with a mass of 2~3 times that of tetrahydrofuran, frozen at -40~-60℃ for 20~30 minutes, filtered and vacuum dried to obtain polyethylene glycol p-toluenesulfonate.

5. The method for preparing a polyethylene filter membrane for a homogeneous bag according to claim 1, wherein: In the above step (4): the preparation method of epoxidized soybean lecithin is as follows: soybean lecithin, catalyst acidic cation exchange resin and glacial acetic acid are mixed in a mass ratio of 8-10:0.8-0.9:1, stirred and heated to 62-66°C at 50-100 rpm, and hydrogen peroxide 0.5-0.6 times the mass of soybean lecithin is added dropwise at a rate of 3-5 ml / min. After the addition is completed, the mixture is reacted for 5-8 hours, cooled to 40-45°C, and the pH is adjusted to 6.8-7.2 with sodium hydroxide. The reaction is continued for 15-30 minutes, and then washed with saturated sodium chloride solution and deionized water for 3-5 times in sequence, and finally distilled under reduced pressure to obtain epoxidized soybean lecithin.

6. The method for preparing a polyethylene filter membrane for a homogeneous bag according to claim 1, characterized in that: In the above step (5), the mass ratio of the composite polyethylene filter membrane, the modified phospholipid and the triethylamine is 1:8~15:0.2~0.4.

Images