Acid-resistant high-strength plastic bag and preparation method thereof

Abstract

The present invention discloses an acid-resistant high-strength plastic bag and a preparation method thereof, and relates to the technical field of plastic bag preparation. The present invention utilizes a hydroxy-terminated polysiloxane to react with phenylphosphoryl dichloride to impart silicon / phosphorus elements to polylactic acid, which has a flame retardant effect; coconut shell fiber then reacts with 3-chloropropylmethyldiethoxysilane to improve hydrophobicity and prevent acidic solutions from adhering to the surface; trifluoromethanesulfonic acid then reacts with the chlorine atoms of 3-chloropropylmethyldiethoxysilane to introduce sulfonate groups, preventing the plastic from undergoing a replacement reaction with an acidic medium and improving acid resistance; finally, modified polylactic acid is mixed with modified coconut shell fiber to prepare an acid-resistant high-strength plastic bag. The acid-resistant high-strength plastic bag prepared by the present invention has flame retardant, corrosion-resistant, and high-strength effects.

Description

Technical Field

[0001] The invention relates to the technical field of plastic bag preparation, in particular to an acid-resistant high-strength plastic bag and a preparation method thereof. Background Art

[0002] In daily life, people use various packaging bags when purchasing goods. The most commonly used ones are plastic bags. Plastic bags are made of plastic materials such as polyethylene. They have the advantages of light weight and low price. They are very popular among consumers and manufacturers. However, because the degradation cycle of general plastic bags is long and they are difficult to handle, they have a great impact on the environment. Therefore, people are focusing on the development of degradable plastic bags.

[0003] Polylactic acid (PLA), a thermoplastic aliphatic polyester with excellent biocompatibility, biodegradability, and ease of molding and processing, is a promising new green material. However, due to its unique linear helical structure, it exhibits certain brittleness, a slow crystallization rate, and is susceptible to hydrolysis and acid corrosion. Furthermore, it suffers from flammability and severe flame leakage, severely limiting its widespread application. Therefore, developing an acid-resistant, flame-retardant, and high-strength plastic bag is crucial. Summary of the Invention

[0004] The object of the present invention is to provide an acid-resistant high-strength plastic bag and a preparation method thereof, so as to solve the problems existing in the prior art.

[0005] In order to solve the above technical problems, the present invention provides the following technical solutions: an acid-resistant high-strength plastic bag, wherein the acid-resistant high-strength plastic bag comprises modified coconut shell fiber, phenolic resin, and modified polylactic acid.

[0006] Furthermore, the modified coconut shell fiber is prepared from coconut shell fiber, 3-chloropropylmethyldiethoxysilane and trifluoromethanesulfonic acid.

[0007] Furthermore, the modified polylactic acid is prepared from a modified flame retardant and polylactic acid.

[0008] Furthermore, the modified flame retardant is prepared from terminal hydroxyl polysiloxane, phenylphosphoryl dichloride and ethanolamine.

[0009] Furthermore, a method for preparing an acid-resistant high-strength plastic bag comprises the following steps:

[0010] (1) 5-15 parts of coconut shell fiber, 40-120 parts of ethanol, and 20-45 parts of 3-chloropropylmethyldiethoxysilane are mixed, reacted at 20-30°C for 4-24 hours, the fiber is taken out, and then placed in 30-55 parts of triethylamine, and then 25-50 parts of trifluoromethanesulfonic acid are added at -5-5°C, and reacted for 2-6 hours to obtain modified coconut shell fiber;

[0011] (2) fusing 50 to 150 parts of a phenolic resin having a molecular weight of 10,000 to 20,000 with 30 to 90 parts of modified coconut shell fiber to obtain modified coconut shell fiber particles;

[0012] (3) 6 to 14 parts of hydroxy-terminated polysiloxane with a molecular weight of 15,000 to 25,000 and 2 to 6 parts of triethylamine are dissolved in 24 to 56 parts of dichloromethane, cooled to -5 to 5°C, and 5 to 15 parts of phenylphosphoryl dichloride are added under stirring at 1000 rpm, and the mixture is reacted for 5 to 15 hours. The mixture is then extracted with HCl solution, NaHCO3 aqueous solution and distilled water for multiple times, dried and concentrated, and then 24 to 60 parts of ethanolamine and 100 to 240 parts of anhydrous ethanol are added to react at 20-30°C for 40 to 50 hours. The modified flame retardant is obtained after concentration;

[0013] (4) Mixing 40 to 60 parts of polylactic acid and 4 to 12 parts of a modified flame retardant, and then mixing them in an internal mixer at 170 to 200° C. for 10 to 20 minutes to obtain modified polylactic acid;

[0014] (5) 6-10 parts of modified coconut fiber particles, 50-80 parts of modified polylactic acid, 0.4-0.6 parts of plasticizer, and 0.2-0.8 parts of stabilizer are mixed and stirred in a high-speed mixer at a speed of 700-900 r / min for 20-50 min, and then sent to a twin-screw extruder for extrusion granulation at 180° C., and blow-molded to obtain acid-resistant high-strength plastic bags.

[0015] Furthermore, the fusion granulation process in step (2) is as follows: the raw materials are put into a high-speed mixer set in advance at 120-150° C., and mixed and stirred for 30-40 minutes at a speed of 600-800 r / min; then the high-speed mixer is turned off, and the temperature inside the mixer is naturally cooled to 40-50° C., and then the obtained mixture is transported to a twin-screw extruder for extrusion granulation.

[0016] Furthermore, the HCl solution in step (3) is 1 mol / L, and the NaHCO3 aqueous solution is a saturated solution.

[0017] Furthermore, the extraction times in step (3) are 3 to 6 times, anhydrous Na2SO4 or anhydrous MgSO4 is used for drying, and the concentration conditions are: 30 to 38°C, vacuum degree -0.06MPa to -0.04MPa, and concentration time 3h.

[0018] Furthermore, the plasticizer in step (5) is selected from any one of diethyl phthalate, dibutyl phthalate and dicyclohexyl phthalate.

[0019] Furthermore, the stabilizer in step (5) includes one or more of barium stearate, zinc stearate, and sodium alginate.

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

[0021] The present invention fuses and granulates modified coconut shell fiber and phenolic resin, constructs a fiber-reinforced network structure inside the resin matrix to further enhance the mechanical properties, and then melt-mixes with modified polylactic acid. The acid-resistant and high-strength plastic bags are obtained through blow molding to achieve flame retardancy, corrosion resistance and high strength.

[0022] First, the present invention utilizes the reaction of terminal hydroxyl polysiloxane with phenylphosphoryl dichloride. The hydroxyl groups in the polysiloxane replace the chlorine atoms in the phenylphosphoryl dichloride to obtain a silicon / phosphorus-containing modified flame retardant. On this basis, the silicon / phosphorus-containing modified flame retardant is combined with the active groups of polylactic acid to form a stable modified flame-retardant polylactic acid. When burned, the modified flame retardant polylactic acid decomposes to produce phosphorus oxides and water, promotes the formation of a carbon layer, inhibits heat transfer and smoke release, and prevents the plastic bag from continuing to burn.

[0023] Secondly, modified coconut shell fiber is prepared from coconut shell fiber, 3-chloropropylmethyldiethoxysilane and trifluoromethanesulfonic acid; 3-chloropropylmethyldiethoxysilane is used to react with the hydroxyl groups on the surface of coconut shell fiber to improve the hydrophobic properties of the fiber, thereby improving the hydrophobic effect of the plastic, which can effectively prevent the adhesion of acidic solutions on the surface and initially achieve an acid-resistant effect; then trifluoromethanesulfonic acid reacts with the chlorine atoms in 3-chloropropylmethyldiethoxy to introduce sulfonate groups, making it impossible for the plastic to undergo a replacement reaction with the acidic medium, thereby improving the acid resistance of the plastic. DETAILED DESCRIPTION

[0024] 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 embodiments described 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 efforts are within the scope of protection of the present invention.

[0025] In order to more clearly illustrate the method provided by the present invention, the following examples are provided in detail. The test methods for various indicators of the acid-resistant high-strength plastic bags prepared in the following examples are as follows:

[0026] Tensile strength: The tensile strength of the embodiment and the comparative example of the same size was tested according to GB / T13022-91 "Test method for tensile properties of plastic films".

[0027] Acid resistance: The examples and comparative examples of the same size were respectively placed in a 1 mol / L hydrochloric acid solution and soaked for 100 hours. The grades were expressed as follows: Grade 0 - the mass change rate before and after corrosion is less than 0.001%; Grade 1 - the mass change rate before and after corrosion is greater than 0.001% and less than 0.010%; Grade 2 - the mass change rate before and after corrosion is greater than 0.010% and less than 0.030%; Grade 3 - the mass change rate before and after acid corrosion is greater than 0.030% and less than 0.050%; Grade 4 - the mass change rate before and after corrosion is greater than 0.050% and less than 0.10%.

[0028] Oxygen index: The examples and comparative examples of the same size were tested according to GB / T2406-1993.

[0029] Example 1

[0030] (1) 5 parts of coconut shell fiber, 40 parts of ethanol, and 20 parts of 3-chloropropylmethyldiethoxysilane were mixed and reacted at 20°C for 4 hours. The fiber was taken out and placed in 30 parts of triethylamine. Subsequently, 25 parts of trifluoromethanesulfonic acid were added at -5°C and reacted for 2 hours to obtain modified coconut shell fiber.

[0031] (2) 50 parts of phenolic resin with a molecular weight of 10,000 and 30 parts of modified coconut shell fiber were put into a high-speed mixer set at 120° C. in advance, and mixed and stirred at a speed of 600 r / min for 30 minutes; then the high-speed mixer was turned off, and the temperature in the mixer was naturally cooled to 40° C., and the resulting mixture was transported to a twin-screw extruder for extrusion granulation to obtain modified coconut shell fiber particles;

[0032] (3) 6 parts of 15000 molecular weight hydroxyl-terminated polysiloxane and 2 parts of triethylamine were dissolved in 24 parts of dichloromethane, cooled to -5°C, and 5 parts of phenylphosphoryl dichloride were added at 1000 rpm for 5 hours. The mixture was then extracted three times with 1 mol / L HCl solution, saturated NaHCO3 aqueous solution and distilled water, dried with anhydrous Na2SO4, concentrated at 30°C and vacuum degree of -0.06 MPa for 3 hours, and then 24 parts of ethanolamine and 100 parts of anhydrous ethanol were added for 40 hours at 20°C. The mixture was concentrated at 30°C and vacuum degree of -0.06 MPa for 3 hours to obtain a modified flame retardant.

[0033] (4) 40 parts of polylactic acid and 4 parts of modified flame retardant were mixed and placed in an internal mixer at 170° C. for 10 minutes to obtain modified polylactic acid;

[0034] (5) 6 parts of modified coconut fiber particles, 50 parts of modified polylactic acid, 0.4 parts of diethyl phthalate, and 0.2 parts of zinc stearate were mixed and stirred in a high-speed mixer at a speed of 700 r / min for 20 minutes, and then sent to a twin-screw extruder for extrusion granulation at 180°C, and blow-molded to obtain acid-resistant high-strength plastic bags.

[0035] Example 2

[0036] (1) 10 parts of coconut shell fiber, 80 parts of ethanol, and 33 parts of 3-chloropropylmethyldiethoxysilane were mixed and reacted at 25°C for 14 hours. The fiber was taken out and placed in 43 parts of triethylamine. Subsequently, 38 parts of trifluoromethanesulfonic acid were added at 0°C and reacted for 4 hours to obtain modified coconut shell fiber.

[0037] (2) 100 parts of phenolic resin with a molecular weight of 15,000 and 60 parts of modified coconut shell fiber were put into a high-speed mixer set at 135° C. in advance, and mixed and stirred at a speed of 700 r / min for 35 minutes; then the high-speed mixer was turned off, and the temperature in the machine was naturally cooled to 45° C., and the resulting mixture was transported to a twin-screw extruder for extrusion granulation to obtain modified coconut shell fiber particles;

[0038] (3) Dissolve 10 parts of hydroxy-terminated polysiloxane with a molecular weight of 20,000 and 4 parts of triethylamine in 40 parts of dichloromethane, cool to 0°C, add 10 parts of phenylphosphoryl dichloride while stirring at 1000 rpm, and react for 10 hours; then extract with 1 mol / L HCl solution, saturated NaHCO3 aqueous solution and distilled water four times, dry with anhydrous MgSO4, concentrate at 35°C and vacuum degree of -0.05 MPa for 3 hours, then add 42 parts of ethanolamine and 170 parts of anhydrous ethanol, react at 25°C for 45 hours, and concentrate at 34°C and vacuum degree of -0.05 MPa for 3 hours to obtain a modified flame retardant;

[0039] (4) 50 parts of polylactic acid and 8 parts of modified flame retardant were mixed and placed in an internal mixer at 185°C for 15 minutes to obtain modified polylactic acid;

[0040] (5) 8 parts of modified coconut fiber particles, 65 parts of modified polylactic acid, 0.5 parts of dicyclohexyl phthalate, and 0.4 parts of sodium alginate were mixed and stirred in a high-speed mixer at a speed of 800 r / min for 35 minutes, and then sent to a twin-screw extruder for extrusion granulation at 180°C, and blow-molded to obtain acid-resistant high-strength plastic bags.

[0041] Example 3

[0042] (1) 15 parts of coconut shell fiber, 120 parts of ethanol, and 45 parts of 3-chloropropylmethyldiethoxysilane were mixed and reacted at 30°C for 14 hours. The fiber was taken out and placed in 55 parts of triethylamine. Subsequently, 50 parts of trifluoromethanesulfonic acid were added at 5°C and reacted for 6 hours to obtain modified coconut shell fiber.

[0043] (2) 150 parts of phenolic resin with a molecular weight of 20,000 and 90 parts of modified coconut shell fiber were put into a high-speed mixer set at 150° C. in advance, and mixed and stirred at a speed of 800 r / min for 40 minutes; then the high-speed mixer was turned off, and the temperature in the machine was naturally cooled to 50° C., and the resulting mixture was transported to a twin-screw extruder for extrusion granulation to obtain modified coconut shell fiber particles;

[0044] (3) 14 parts of hydroxy-terminated polysiloxane with a molecular weight of 25,000 and 6 parts of triethylamine were dissolved in 56 parts of dichloromethane, cooled to -5°C, and 15 parts of phenylphosphoryl dichloride were added under stirring at 1000 rpm, and the mixture was reacted for 15 hours; then, the mixture was extracted five times with 1 mol / L HCl solution, saturated NaHCO3 aqueous solution, and distilled water, dried with anhydrous MgSO4, concentrated at 38°C and vacuum degree of -0.04 MPa for 3 hours, and then 60 parts of ethanolamine and 240 parts of anhydrous ethanol were added to react at 30°C for 50 hours, and concentrated at 38°C and vacuum degree of -0.04 MPa for 3 hours to obtain a modified flame retardant;

[0045] (4) 60 parts of polylactic acid and 12 parts of modified flame retardant were mixed and placed in an internal mixer at 200°C for 20 minutes to obtain modified polylactic acid;

[0046] (5) 10 parts of modified coconut fiber particles, 80 parts of modified polylactic acid, 0.6 parts of dibutyl phthalate, and 0.8 parts of barium stearate were mixed and stirred in a high-speed mixer at a speed of 800 r / min for 35 minutes, and then sent to a twin-screw extruder for extrusion granulation at 180°C, and blow-molded to obtain acid-resistant high-strength plastic bags.

[0047] Comparative Example 1

[0048] The difference between Comparative Example 1 and Example 2 is only in step (1), which is modified as follows: 10 parts of coconut shell fiber, 80 parts of ethanol, and 33 parts of 3-chloropropylmethyldiethoxysilane are mixed and reacted at 25° C. for 14 hours to obtain modified coconut shell fiber. The remaining preparation steps are the same as those in Example 2.

[0049] Comparative Example 2

[0050] Comparative Example 2 differs from Example 2 only in step (1), which is modified as follows: 10 parts of coconut shell fiber, 43 parts of triethylamine, and 80 parts of ethanol are mixed, followed by the addition of 38 parts of trifluoromethanesulfonic acid at 0°C and the reaction for 4 hours to obtain modified coconut shell fiber. The remaining preparation steps are the same as those of Example 2.

[0051] Comparative Example 3

[0052] Comparative Example 3 differs from Example 2 only in that steps (3) and (4) are omitted, and step (5) is modified as follows: 8 parts of modified coconut fiber particles, 65 parts of polylactic acid, 0.5 parts of dicyclohexyl phthalate, and 0.4 parts of sodium alginate are mixed and stirred in a high-speed mixer at a speed of 800 r / min for 35 minutes, and then fed into a twin-screw extruder for extrusion and granulation at 180° C., and blow-molded to produce an acid-resistant high-strength plastic bag. The remaining preparation steps are the same as those in Example 2.

[0053] Comparative Example 4

[0054] Comparative Example 4 differs from Example 2 only in that step (3) is omitted and step (5) is replaced by mixing 10 parts of modified coconut fiber, 100 parts of phenolic resin, 80 parts of modified polylactic acid, 0.6 parts of dibutyl phthalate, and 0.8 parts of barium stearate in a high-speed mixer at a speed of 800 r / min for 35 minutes, then feeding the mixture into a twin-screw extruder at 180° C. for extrusion granulation, and blow molding to produce an acid-resistant high-strength plastic bag. The remaining preparation steps are the same as those in Example 2.

[0055] Effect Examples

[0056] Table 1 below shows the performance analysis results of the acid-resistant high-strength plastic bags of Examples 1 to 3 of the present invention and Comparative Examples 1 to 4.

[0057] Tensile strength / MPa Acid resistance / grade Oxygen index% Example 1 22.5 0 38 Example 2 22.9 0 41 Example 3 23.4 0 39 Comparative Example 1 17.6 5 30 Comparative Example 2 16.3 4 28 Comparative Example 3 17.5 1 18 Comparative Example 4 15.1 1 29

[0058] Comparison of the experimental data of Examples 1, 2, and 3 with Comparative Example 1 shows that the sulfonate group of trifluoromethanesulfonic acid, as a strong acid group, can prevent the plastic from reacting with the acidic medium, thereby improving the corrosion resistance level. Comparison of the experimental data of Examples 1, 2, and 3 with Comparative Example 2 shows that the reaction of 3-chloropropylmethyldiethoxysilane with the hydroxyl groups on the surface of coconut fiber can improve the hydrophobicity, prevent the acidic solution from adhering to the surface, and achieve an acid-resistant effect. Comparison of the experimental data of Examples 1, 2, and 3 with Comparative Example 3 shows that by reacting hydroxyl-terminated polysiloxane with phenylphosphoryl dichloride, the hydroxyl groups in the polysiloxane replace the chlorine atoms in the phenylphosphoryl dichloride to obtain a silicon / phosphorus-containing modified flame retardant, which, after combining with the active groups of polylactic acid, can effectively prevent the burning of plastic bags. Comparison of the experimental data of Examples 1, 2, and 3 with Comparative Example 4 shows that by first fusing and granulating the modified coconut fiber with the phenolic resin, a fiber-reinforced network structure can be constructed within the resin matrix, thereby enhancing the mechanical properties.

[0059] 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. An acid-resistant high-strength plastic bag, comprising modified coconut shell fiber, phenolic resin, and modified polylactic acid, characterized in that: The method comprises the following preparation steps: (1) 5-15 parts of coconut shell fiber, 40-120 parts of ethanol, and 20-45 parts of 3-chloropropylmethyldiethoxysilane were mixed and reacted at 20-30 ° C for 4-24 hours. The fiber was taken out and placed in 30-55 parts of triethylamine. Subsequently, 25-50 parts of trifluoromethanesulfonic acid were added at -5-5 ° C and reacted for 2-6 hours to obtain modified coconut shell fiber. (2) 50-150 parts of phenolic resin with a molecular weight of 10,000-20,000 and 30-90 parts of modified coconut shell fiber are blended and granulated to obtain modified coconut shell fiber particles; (3) Dissolve 6 to 14 parts of 15,000 to 25,000 molecular weight hydroxyl-terminated polysiloxane and 2 to 6 parts of triethylamine in 24 to 56 parts of dichloromethane, cool to -5 to 5°C, add 5 to 15 parts of phenylphosphoryl dichloride while stirring at 1000 rpm, react for 5 to 15 hours, then extract with HCl solution, NaHCO3 aqueous solution and distilled water for multiple times, dry and concentrate, then add 24 to 60 parts of ethanolamine and 100 to 240 parts of anhydrous ethanol and react at 20-30°C for 40 to 50 hours, and concentrate to obtain a modified flame retardant; (4) Mix 40-60 parts of polylactic acid and 4-12 parts of modified flame retardant and place them in an internal mixer at 170-200°C for 10-20 minutes to obtain modified polylactic acid; (5) 6-10 parts of modified coconut fiber particles, 50-80 parts of modified polylactic acid, 0.4-0.6 parts of plasticizer, and 0.2-0.8 parts of stabilizer were mixed and stirred in a high-speed mixer at a speed of 700-900 r / min for 20-50 min, and then sent to a twin-screw extruder for extrusion granulation at 180°C, and blow-molded to obtain acid-resistant high-strength plastic bags.

2. The acid-resistant high-strength plastic bag according to claim 1, characterized in that: The fusion granulation process of step (2) is as follows: the raw materials are put into a high-speed mixer set at 120-150°C in advance, and mixed and stirred for 30-40 minutes at a speed of 600-800 r / min; then the high-speed mixer is turned off, and the temperature inside the mixer is naturally cooled to 40-50°C, and then the obtained mixed material is transported to a twin-screw extruder for extrusion granulation.

3. The acid-resistant high-strength plastic bag according to claim 1, characterized in that: The HCl solution in step (3) is 1 mol / L, and the NaHCO3 aqueous solution is a saturated solution.

4. The acid-resistant high-strength plastic bag according to claim 1, characterized in that: The extraction times in step (3) are 3 to 6 times, anhydrous Na2SO4 or anhydrous MgSO4 is used for drying, and the concentration conditions are: 30 to 38°C, vacuum degree -0.06MPa to -0.04MPa, and concentration time 3h.

5. The acid-resistant high-strength plastic bag according to claim 1, characterized in that: The plasticizer in step (5) is selected from any one of diethyl phthalate, dibutyl phthalate and dicyclohexyl phthalate.

6. The acid-resistant high-strength plastic bag according to claim 1, characterized in that: The stabilizer in step (5) includes one or more of barium stearate, zinc stearate, and sodium alginate.