Preparation process of environment-friendly high polymer material packaging bag

Abstract

The invention relates to a preparation process of an environment-friendly high polymer material packaging bag, and belongs to the technical field of high polymer materials. According to the environment-friendly high polymer material packaging bag and the preparation method thereof, the modifying agent is self-made, the modifying agent, PBS and LDPE are blended, then melt extrusion is conducted, bag making is conducted, and the environment-friendly high polymer material packaging bag is obtained, an o-hydroxyl diaromatic ketone structure in the modifying agent can effectively absorb ultraviolet light, and a quaternary ammonium salt structure in the modifying agent can play an anti-static effect while expanding the absorption wavelength range; in addition, a long-chain alkyl structure in the modifier is similar to a PE structure, and a polar group in the modifier is similar to the polarity of PBS, so that the interface lubrication and compatibilization effects are achieved, the mechanical performance of the blending material is improved, the packaging bag is more durable, the damage risk in the use process is reduced, meanwhile, the melt viscosity is reduced, the melt strength is improved, and the service life of the packaging bag is prolonged. And the production efficiency and the yield of packaging bags are improved.

Description

Technical Field

[0001] This invention belongs to the field of polymer materials technology, specifically, it relates to a process for preparing environmentally friendly polymer material packaging bags. Background Technology

[0002] Polybutyric acid dibutyl succinate (PBS) is a promising biodegradable plastic. Due to its excellent biodegradability, it can be decomposed into carbon dioxide and water by microorganisms in natural environments. At the same time, the monomer succinic acid of PBS can be obtained from renewable resources such as starch through bio-fermentation, reducing dependence on non-renewable petroleum resources. In addition, it has good processing performance, making it widely used in the packaging bag industry.

[0003] Despite its significant advantages, PBS's inherent material defects severely limit its commercial application in the packaging field. Compared to traditional polyethylene (PE) and polypropylene (PP), PBS has lower toughness and tensile strength, and its brittle texture makes it difficult to withstand the mechanical stress during packaging or transportation. While blending with LDPE can improve overall mechanical properties, direct blending leads to severe phase separation, resulting in deterioration of packaging bag performance. Furthermore, PBS is highly sensitive to ultraviolet light; prolonged outdoor use or storage can cause the material to become brittle, discolored, and rapidly degrade in performance, shortening product lifespan. As a polymer material, PBS has high resistivity, making it prone to generating and accumulating static electricity during use due to friction. This static electricity attracts dust, contaminates packaging contents, and can even cause operational inconvenience and discharge risks during production. Current technologies typically improve these properties by adding small-molecule plasticizers, antistatic agents, and ultraviolet absorbers. However, compounding multiple single-function additives leads to complex formulations and a series of new problems, such as interference between components, poor compatibility, easy migration and precipitation, and short-lasting effects.

[0004] Based on this, the present invention will provide a preparation process for environmentally friendly polymer material packaging bags. Summary of the Invention

[0005] The purpose of this invention is to provide a process for preparing environmentally friendly polymer packaging bags to solve the problems mentioned in the background art.

[0006] The objective of this invention can be achieved through the following technical solutions:

[0007] A process for preparing environmentally friendly polymer packaging bags includes the following steps:

[0008] Step 1: Add pyridine carboxylic acid, alkylphenol, p-toluenesulfonic acid and toluene to a four-necked flask, attach a condenser, thermometer and water separator, turn on magnetic stirring, and react at 120-130℃ for 2-4 hours. After cooling to room temperature, remove the solvent by rotary evaporation, wash the product with water and dry it to obtain the precursor of the UV absorber.

[0009] The second step involves adding the UV absorber precursor, aluminum trichloride, and o-dichlorobenzene to a three-necked flask, attaching a condenser and a thermometer, turning on the magnetic stirrer, and reacting at 140–160°C for 4–6 hours. After the reaction is complete, dilute hydrochloric acid is added for hydrolysis, and the aqueous phase is removed by separation. The product is then subjected to rotary evaporation to remove some of the solvent. The remaining mixture is then dissolved in toluene and evaporated to dryness to obtain the UV absorber.

[0010] The third step involves adding the ultraviolet absorber, dimethyl carbonate, and methanol to a high-pressure reactor under nitrogen protection and reacting at 100–120°C for 8–12 hours. After the reaction is complete, the mixture is cooled to room temperature and the product is removed. The product is then dried by rotary evaporation to obtain the modifier.

[0011] The fourth step involves mixing poly(dibutyl succinate), low-density polyethylene, modifier, montmorillonite, and antioxidant, then adding the mixture to a screw extruder for melt extrusion. After blowing and cooling, a poly(dibutyl succinate) base film is formed. The poly(dibutyl succinate) base film is then printed, laminated, and bag-made to obtain an environmentally friendly polymer packaging bag.

[0012] Furthermore, the pyridinecarboxylic acid in the first step is either isonicotinic acid or nicotinic acid.

[0013] Furthermore, the alkylphenol in the first step is at least one of 4-decylphenol, 4-dodecylphenol, and 4-tetradecylphenol.

[0014] Furthermore, in the first step, the mass ratio of pyridine carboxylic acid, alkylphenol, p-toluenesulfonic acid, and toluene is 5–6.5: 11.5–14.5: 1–2: 80–100.

[0015] Furthermore, the mass fraction of the dilute hydrochloric acid in the second step is 10-20%.

[0016] Furthermore, in the second step, the mass ratio of the UV absorber precursor, aluminum trichloride, and o-dichlorobenzene is 12.5–14.5: 3.5–5.5: 60–80.

[0017] Furthermore, in the third step, the mass ratio of the ultraviolet absorber, dimethyl carbonate, and methanol is 11.6–14: 2.4–3: 50–70.

[0018] Furthermore, the antioxidant in the fourth step is at least one of antioxidant 1010, antioxidant 1076, and antioxidant 330.

[0019] Furthermore, in the fourth step, the mass ratio of poly(dibutyric acid succinate), low-density polyethylene, modifier, montmorillonite, and antioxidant is 30–40: 60–70: 8–10: 10–15: 0.1–0.3.

[0020] Furthermore, the temperature of melt extrusion in the fourth step is 160–180°C.

[0021] The beneficial effects of this invention are:

[0022] 1) This invention uses pyridinecarboxylic acid and alkylphenol as raw materials to undergo an esterification reaction to obtain a precursor for an anti-UV absorber. Then, using the precursor as raw material, a Flaes rearrangement reaction is carried out to obtain the anti-UV absorber. Next, the anti-UV absorber is reacted with dimethyl carbonate as raw material to obtain a quaternary ammonium salt modifier. Finally, PBS, LDPE, the modifier, montmorillonite, and an antioxidant are blended, melt-extruded, and then printed, laminated, and bag-made to obtain an environmentally friendly polymer packaging bag. The modifier reduces melt viscosity through interfacial lubrication, which helps LDPE and PBS to be more easily sheared and dispersed during melt blending. It also increases melt strength by inhibiting phase separation, contributing to a more uniform phase structure and making the blend easier to handle in the bag-making process, thereby improving the production efficiency and yield of the packaging bags.

[0023] 2) The modifier of this invention contains an o-hydroxy diaromatic ketone structure. When exposed to ultraviolet light, the ketone group and the active hydrogen on the adjacent ring can form reversible intramolecular hydrogen bonds, absorbing the energy of ultraviolet light and converting it into heat energy. Furthermore, the conjugated system of the o-hydroxy diaromatic ketone contains a quaternary ammonium salt structure, enabling it to absorb ultraviolet light with longer wavelengths. Simultaneously, the quaternary ammonium salt structure, as an ionicly conductive group, can reduce the surface resistance of the polymer packaging bag, hindering static electricity accumulation and achieving an antistatic effect. This significantly reduces the adsorption of dust to the surface of the packaging bag, effectively preventing dust adhesion and keeping the packaging bag clean.

[0024] 3) The long-chain alkyl groups in the modifier of this invention are similar in structure to LDPE, and therefore have good compatibility with LDPE. They can be embedded into the LDPE phase through intermolecular forces. The ester groups and quaternary ammonium salt polar groups are similar in polarity to PBS. Therefore, the modifier will accumulate at the interface between the LDPE and PBS phases, buffering the polarity difference, improving the adhesion between the phase interfaces of the blend, and playing a role in interface lubrication and compatibilization. This effectively avoids brittle fracture caused by phase separation, thereby improving the mechanical properties of the blend material, reducing the risk of breakage during use, and making the packaging bag more durable. Detailed Implementation

[0025] The technical solutions of the embodiments of this application will be clearly and completely described below. Obviously, the described embodiments are only some, not all, of the embodiments of this application. Based on the embodiments in this application specification, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection claimed in this application.

[0026] The raw materials used in this invention are not particularly restricted in terms of their source; they can be purchased from the market or prepared using conventional methods known to those skilled in the art.

[0027] Example 1

[0028] A process for preparing environmentally friendly polymer packaging bags includes the following steps:

[0029] Step 1: Add 5g isonicotinic acid, 11.5g 4-decylphenol, 1g p-toluenesulfonic acid and 80g toluene to a four-necked flask, attach a condenser, thermometer and water separator, turn on magnetic stirring, react at 120℃ for 4h, cool to room temperature and remove the solvent by rotary evaporation, then wash the product with water and dry to obtain the precursor of the UV absorber.

[0030] Step 2: Add 12.5g of UV absorber precursor, 3.5g of aluminum trichloride and 60g of o-dichlorobenzene to a three-necked flask, attach a condenser and thermometer, turn on magnetic stirring, and react at 140℃ for 6 hours. After the reaction is complete, add 10% dilute hydrochloric acid to hydrolyze and separate the aqueous phase. Then, remove part of the solvent by rotary evaporation of the product. Finally, dissolve the remaining mixture in toluene and evaporate to dryness to obtain the UV absorber.

[0031] The third step involves adding 11.6g of ultraviolet absorber, 2.4g of dimethyl carbonate and 60g of methanol to a high-pressure reactor under nitrogen protection. The reaction is carried out at 100°C for 12 hours. After the reaction is completed, the mixture is cooled to room temperature and the product is removed. The product is then dried by rotary evaporation to obtain the modifier.

[0032] Step 4: Mix 30g of poly(dibutyl succinate), 70g of low-density polyethylene, 8g of modifier, 10g of montmorillonite, and 0.1g of antioxidant, then add the mixture to a screw extruder. After melt extrusion at 160℃, the mixture is blown and cooled to form a poly(dibutyl succinate) base film. The poly(dibutyl succinate) base film is then printed, laminated, and bag-made to obtain an environmentally friendly polymer packaging bag.

[0033] Example 2

[0034] A process for preparing environmentally friendly polymer packaging bags includes the following steps:

[0035] Step 1: Add 5.75g of nicotinic acid, 13g of 4-dodecylphenol, 1.5g of p-toluenesulfonic acid and 90g of toluene to a three-necked flask, attach a condenser and a thermometer, turn on magnetic stirring, and react at room temperature for 5.5h. After cooling to room temperature, remove the solvent by rotary evaporation, wash the product with water and dry it to obtain the precursor of the UV absorber.

[0036] Step 2: Add 13.5g of UV absorber precursor, 4.5g of aluminum trichloride and 70g of o-dichlorobenzene to a three-necked flask, attach a condenser and thermometer, turn on magnetic stirring, and react at 150℃ for 5h. After the reaction is completed, cool to room temperature, add 15% dilute hydrochloric acid to hydrolyze and separate the aqueous phase, then remove part of the solvent by rotary evaporation of the product, and then dissolve the remaining mixture in toluene and evaporate to dryness to obtain the UV absorber.

[0037] The third step involves adding 12.8g of ultraviolet absorber, 2.7g of methyl tetradecanoate and 60g of methanol to a high-pressure reactor under nitrogen protection. The reaction is carried out at 110℃ for 10 hours. After the reaction is completed, the mixture is cooled to room temperature and the product is removed. The product is then dried by rotary evaporation to obtain the modifier.

[0038] Step 4: Mix 35g of poly(dibutyl succinate), 65g of low-density polyethylene, 9g of modifier, 12.5g of montmorillonite, and 0.2g of antioxidant, then add the mixture to a screw extruder. After melt extrusion at 170℃, the mixture is inflated and cooled to form a poly(dibutyl succinate) base film. The poly(dibutyl succinate) base film is then printed, laminated, and bag-made to obtain an environmentally friendly polymer packaging bag.

[0039] Example 3

[0040] A process for preparing environmentally friendly polymer packaging bags includes the following steps:

[0041] Step 1: Add 6.5g isonicotinic acid, 14.5g 4-tetradecylphenol, 2g p-toluenesulfonic acid and 100g toluene to a three-necked flask, attach a condenser and thermometer, turn on magnetic stirring, and react at room temperature for 6 hours. After cooling to room temperature, remove the solvent by rotary evaporation, wash the product with water and dry it to obtain the precursor of the UV absorber.

[0042] Step 2: Add 14.5g of UV absorber precursor, 5.5g of aluminum trichloride and 80g of o-dichlorobenzene to a three-necked flask, attach a condenser and thermometer, turn on magnetic stirring, and react at 160℃ for 4 hours. After the reaction is completed, cool to room temperature, add 20% dilute hydrochloric acid to hydrolyze and separate the aqueous phase, then remove part of the solvent by rotary evaporation of the product, and then dissolve the remaining mixture in toluene and evaporate to dryness to obtain the UV absorber.

[0043] The third step involves adding 14g of ultraviolet absorber, 3g of methyl hexadecanoate and 70g of methanol to a high-pressure reactor under nitrogen protection. The reaction is carried out at 120°C for 8 hours. After the reaction is completed, the mixture is cooled to room temperature and the product is removed. The product is then dried by rotary evaporation to obtain the modifier.

[0044] Step 4: Mix 60g of poly(dibutyl succinate), 40g of low-density polyethylene, 10g of modifier, 15g of montmorillonite, and 0.3g of antioxidant, then add the mixture to a screw extruder. After melt extrusion at 180℃, the mixture is blown and cooled to form a poly(dibutyl succinate) base film. The poly(dibutyl succinate) base film is then printed, laminated, and bag-made to obtain an environmentally friendly polymer packaging bag.

[0045] Comparative Example 1

[0046] The difference between this comparative example and Example 2 is that the modifier is replaced with commercially available benzophenone-based ultraviolet absorber UV-531, while the other raw materials and preparation steps remain unchanged.

[0047] Experimental Example 1

[0048] The environmentally friendly polymer packaging bags from Examples 1-3 and Comparative Example 1 were subjected to performance tests. The tensile strength and elongation at break of each group of environmentally friendly polymer packaging bags were tested according to GB / T1040.2-2006 "Determination of Tensile Properties of Plastics". The accelerated aging test under ultraviolet light was conducted according to GB / T16422.3-2022 "Laboratory Light Source Exposure Test Method for Plastics", and the retention rate of tensile strength and elongation at break of each group of environmentally friendly polymer packaging bags were tested. The surface resistivity of each group of environmentally friendly polymer packaging bags was tested according to GB / T31838.3-2019 "Dielectric and Resistance Properties of Solid Insulating Materials". The test results are shown in Table 1.

[0049] Table 1

[0050] project Tensile strength (MPa) Elongation at break (%) Tensile strength retention rate (%) Elongation at break retention rate (%) Surface resistivity (Ω) Example 1 26.0 282.4 81.3 82.3 <![CDATA[7.4·10 6 ]]> Example 2 26.6 285.7 82.9 83.4 <![CDATA[7.6·10 6 ]]> Example 3 26.9 288.9 83.7 84.1 <![CDATA[7.8·10 6 ]]> Comparative Example 1 18.2 253.6 76.1 72.4 <![CDATA[2.1·10 12 ]]>

[0051] As can be seen from Table 1, Examples 1-3 have higher tensile strength, elongation at break, tensile strength retention rate, elongation at break retention rate, and surface resistivity compared with Comparative Example 1. This indicates that the mechanical properties, UV resistance, and antistatic properties of Examples 1-3 are all superior to those of Comparative Example 1. Combined with Comparative Example 1, it can be seen that the modifier of the present invention effectively improves the compatibility between PBAT and LDPE, thereby improving the overall mechanical properties of the packaging bag, while effectively improving the UV resistance and antistatic properties of the environmentally friendly polymer packaging bag.

[0052] The descriptions of the above embodiments are merely illustrative of the methods and core ideas of the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the present invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A process for preparing environmentally friendly polymer packaging bags, characterized in that, Includes the following steps: Preparation of the modifier: The precursor of the UV absorber is obtained by esterification reaction of pyridine carboxylic acid and alkylphenol. The UV absorber is then obtained by the Fries rearrangement reaction of the UV absorber precursor under the action of aluminum trichloride. Finally, the modifier is obtained by the quaternary ammonium salt reaction of the UV absorber and dimethyl carbonate. Preparation of environmentally friendly polymer packaging bags: Polybutyrate, low-density polyethylene, modifier, montmorillonite, and antioxidant are blended, melt-extruded, and then blown and cooled to form a polybutyrate base film. After printing, lamination, and bag making, environmentally friendly polymer packaging bags are obtained.

2. The process for preparing an environmentally friendly polymer packaging bag according to claim 1, characterized in that, Pyridinecarboxylic acid is one of isonicotinic acid and nicotinic acid.

3. The process for preparing an environmentally friendly polymer packaging bag according to claim 1, characterized in that, The alkylphenol is at least one of 4-decylphenol, 4-dodecylphenol, and 4-tetradecylphenol.

4. The process for preparing an environmentally friendly polymer packaging bag according to claim 1, characterized in that, The mass ratio of pyridine carboxylic acid to alkylphenol is 5–6.5: 11.5–14.

5.

5. The process for preparing an environmentally friendly polymer packaging bag according to claim 1, characterized in that, Pyridine carboxylic acid, alkylphenol, p-toluenesulfonic acid, and toluene are reacted at 120–130 °C for 2–4 h to obtain a precursor of an anti-UV absorber; the precursor of the anti-UV absorber, aluminum trichloride, and o-dichlorobenzene are reacted at 140–160 °C for 4–6 h to obtain an anti-UV absorber; the anti-UV absorber, dimethyl carbonate, and methanol are reacted at 100–120 °C for 8–12 h under nitrogen protection to obtain a modifier.

6. The process for preparing an environmentally friendly polymer packaging bag according to claim 1, characterized in that, The mass ratio of the UV absorber precursor, aluminum trichloride, and dilute hydrochloric acid is 12.5–14.5: 3.5–5.5: 16–26.

7. The process for preparing an environmentally friendly polymer packaging bag according to claim 1, characterized in that, The mass ratio of ultraviolet absorber to dimethyl carbonate is 11.6–14:2.4–3.

8. The process for preparing an environmentally friendly polymer packaging bag according to claim 1, characterized in that, The antioxidant is at least one of antioxidant 1010, antioxidant 1076, and antioxidant 330.

9. The process for preparing an environmentally friendly polymer packaging bag according to claim 1, characterized in that, The temperature for melt extrusion is 160–180℃.

10. The process for preparing an environmentally friendly polymer packaging bag according to claim 1, characterized in that, The mass ratio of poly(dibutyl succinate), low-density polyethylene, modifier, montmorillonite, and antioxidant is 30–40: 60–70: 8–10: 10–15: 0.1–0.3.