Degradable environment-friendly suction nozzle based on PLA / PBS composite material and preparation method of degradable environment-friendly suction nozzle

Abstract

The invention provides a degradable environment-friendly suction nozzle based on a PLA / PBS composite material and a preparation method of the degradable environment-friendly suction nozzle. The suction nozzle is prepared from the following raw materials: polylactic acid, poly (butylene succinate), a flexible modification auxiliary agent and a hydrolysis-resistant auxiliary agent, the hydrolysis-resistant auxiliary agent is selected from a compound of an organic tin stabilizer, a silane coupling agent, triphenyl phosphate and diethyltin dilaurate, and is used for solving the problems of insufficient compatibility, heat resistance, durability, mechanical property and sealing property of the PLA / PBS composite material; the degradable environment-friendly suction nozzle can be safely used for a long time in a high-temperature and high-humidity environment.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of green packaging polymer material modification and molding, and particularly relates to a degradable environment-friendly suction nozzle based on a PLA / PBS composite material and a preparation method thereof. BACKGROUND

[0002] Traditional disposable suction nozzles made of polypropylene, polyethylene and other polymer materials cannot be degraded, are easy to remain in the environment for a long time, and cause serious pollution, which no longer meets the current environmental protection development trend. Compared with the traditional plastics, the biodegradable materials are gradually becoming an ideal choice to replace the traditional plastics due to their renewability and environmental friendliness.

[0003] Polylactic acid (PLA) is a kind of biodegradable material which is pure natural and rich in resources, and has the advantages of high hardness, easy processing and good biocompatibility. However, the glass transition temperature of PLA is low, and the crystallinity is low, which will soften at 50-60℃, and cannot meet the heat resistance requirement of hot drinks. In addition, the toughness of PLA is poor, and the cut is easy to crack during high-speed forming cutting.

[0004] PBS is also an environmentally friendly biobased material, and has good toughness, ductility, elongation at break and high heat distortion temperature. Therefore, the use of PLA / PBS composite can improve the performance of PLA material to a certain extent. However, the compatibility of PBS and PLA is poor, so the compatibility of the blend needs to be solved during preparation. In addition, if the PLA / PBS composite material is used for hot drink suction nozzle, the performance of the material needs to be further regulated, especially the heat resistance, and the hydrolysis resistance, sealing performance and other performances need to be further improved, so that it can be safely and long-term used. SUMMARY

[0005] The present application provides a degradable environment-friendly suction nozzle based on a PLA / PBS composite material and a preparation method thereof, to solve the problems of compatibility, heat resistance, durability, mechanical properties and sealing performance of the PLA / PBS composite material, and to provide a degradable environment-friendly suction nozzle which can be safely and long-term used in high temperature and high humidity environment.

[0006] In order to solve the above technical problems, the present application adopts the following technical scheme: A degradable environment-friendly suction nozzle based on a PLA / PBS composite material and a preparation method thereof, the suction nozzle processing raw material comprises: polylactic acid, polybutylene succinate, flexible modification aid and anti-hydrolysis aid; the anti-hydrolysis aid is selected from the group consisting of organic tin stabilizer, silane coupling agent, triphenyl phosphate and a compound of diethyl tin dilaurylate.

[0007] Furthermore, the organotin stabilizer includes: dibutyltin dilaurate and dibutyltin octanoate; the silane coupling agent includes: γ-aminopropyltriethoxysilane.

[0008] Furthermore, the mass ratio of polylactic acid to polybutylene succinate is 3:7 to 8:2.

[0009] Furthermore, the flexible modifying agent includes: thermoplastic polyurethane and polycaprolactone.

[0010] Furthermore, the raw materials for the nozzle processing also include: lubricant, nucleating agent, and flow aid.

[0011] Furthermore, the lubricant is zinc stearate lubricant, the nucleating agent is an organophosphate nucleating agent, and the flow aid is low molecular weight polycaprolactone.

[0012] Furthermore, based on the total mass of polylactic acid and polybutylene succinate, the amount of lubricant added is 0.8 wt%, the amount of nucleating agent added is 0.5 wt%, and the amount of flow aid added is 0.4 wt%.

[0013] Furthermore, the weight ratio of the triphenyl phosphate ester to the diethyltin dilaurate is 8:2.

[0014] Furthermore, the amount of the anti-hydrolysis additive is 1-3 wt% of the total mass of polylactic acid and polybutylene succinate; the amount of the flexible modification additive is 5-20 wt% of the total mass of polylactic acid and polybutylene succinate.

[0015] Furthermore, the preparation method includes the following steps: all raw materials are mixed in proportion, dried at 65°C for 8 hours, ultrasonic injection molding is used and the nozzle is obtained by cooling and demolding. The parameters of ultrasonic injection molding are set as follows: injection temperature 160-220°C, injection pressure 70-90MPa, mold cooling time 10-20s, and ultrasonic waves with a power of 200-600W are applied during the injection process to assist melting and filling.

[0016] Mold structure design description: The ultrasonic injection molding process used in this invention features a non-standard mold structure designed specifically for the unique properties of heat-sensitive biodegradable materials, equipped with a dedicated ventilation channel and a uniformly distributed water cooling system.

[0017] The venting groove is a pre-set exhaust channel in the mold cavity to ensure that air is discharged in time during the injection of melt, preventing gas retention from causing bubbles, flow marks and structural defects, and ensuring the integrity of the nozzle surface and the internal density.

[0018] The water cooling system consists of multiple water channels distributed in the key cooling areas of the mold, which can quickly and uniformly reduce the mold temperature, effectively inhibit the thermal degradation of heat-sensitive materials, shorten the molding cycle, and improve the dimensional stability and mechanical properties of the product.

[0019] Compared with the prior art, the present invention has the following beneficial effects: (1) In this invention, DBTL, APTES, and (TPP and DETD compound) are selected as anti-hydrolysis additives. In the system, they can not only promote the compatibility between materials, but also indirectly have the effect of anti-hydrolysis, which can regulate the degradation performance of the nozzle and improve its durability under high temperature and high humidity conditions. In addition, DBTL and APTES can also improve heat resistance. (2) The present invention uses ultrasonic waves during the injection molding process to make the melt evenly dispersed and quickly fill the mold, which reduces the risk of thermal degradation of the composite material, that is, improves the thermal stability of the material and is beneficial to the processing and molding of the material; at the same time, the mold adopts a water cooling system to achieve rapid shaping, so that the prepared nozzle has better sealing performance. Detailed Implementation

[0020] The technical solution of the present invention will be further described in detail below with reference to specific embodiments. It should be understood that the following embodiments are merely illustrative and explanatory, and should not be construed as limiting the scope of protection of the present invention.

[0021] Unless otherwise specified, the raw materials and reagents used in the following examples are commercially available products or can be prepared by methods in the prior art.

[0022] Definitions: Heat resistance: refers to the ability of a material to retain its physical properties under high temperature conditions. Materials with good heat resistance are less likely to soften or deform under high temperature conditions.

[0023] Thermal stability: resistance to thermal degradation, focusing on the chemical and structural changes of materials at high temperatures. Materials with good thermal stability are not easily decomposed or degraded at high temperatures and can maintain their basic properties. This has an impact on the processing and molding of the nozzle of this invention.

[0024] Low molecular weight polycaprolactone: refers to polycaprolactone with a molecular weight between 1000 and 50000 Da.

[0025] Suction nozzle performance testing methods: (1) Heat resistance test: Immerse the sample in hot water at 80℃ for 30 minutes. After the test, observe whether there is any obvious deformation in appearance to evaluate the heat resistance of the nozzle under high temperature conditions.

[0026] (2) Sealing performance test: Install the nozzle into the interface of a standard flexible packaging container and fill it with liquid, ensuring that the liquid volume is consistent with the packaging specifications. After sealing, invert the packaging container and let it stand for 24 hours. Observe whether there is any liquid leakage on the surface of the container within 24 hours and record the leakage amount. If there is leakage, measure the volume of the leaked liquid and calculate the drip rate. The drip rate refers to the percentage of liquid volume leaked per unit time by the nozzle structure under specified sealing pressure and time conditions, which is relative to the total filled liquid volume, reflecting its sealing performance. A drip rate ≤ 0.1% is considered to have good sealing performance.

[0027] (3) Mechanical property test: The tensile properties of the nozzle samples shall be tested in accordance with GB / T 1040.3-2006 standard. A standard tensile testing machine shall be used to test the strength and elongation at break of the nozzle samples during the tensile process. The test shall be carried out at room temperature (23℃±2℃) and the size of the sample shall be ensured to meet the standard test requirements.

[0028] (4) Biodegradability test: The samples were buried under simulated industrial composting conditions, with a humidity of 50%–70%, a temperature of 55℃±5℃, and appropriate ventilation. The test period was 60 days, with samples taken every 7 days. After cleaning the sample surface, the mass loss rate and appearance changes were measured, and the structural integrity of the samples was quantitatively and qualitatively evaluated. The mass loss rate, appearance changes, and structural integrity were used as quantitative and qualitative indicators of degradation performance to evaluate the degradation behavior in the composting environment.

[0029] (5) Durability test: The sample was immersed in an 85℃ water bath for 7 days to simulate the aging process of the material under long-term humid and hot conditions. After aging, the sample was removed and the tensile strength was measured according to the tensile property test method described above. The tensile strength retention rate was calculated and defined as the percentage of the tensile strength after aging to the tensile strength before aging. This index is used to evaluate the hydrolysis resistance and durability of the material under humid and hot conditions.

[0030] (I) The effect of anti-hydrolysis additives on mouthpiece performance Examples 1-1, 1-2, 1-3 Polylactic acid (PLA) and polybutylene succinate (PBS) were mixed at a mass ratio of 5:5. Based on the total weight of the mixture, 8 wt% thermoplastic polyurethane (TPU), 1-3 wt% anti-hydrolysis agent, 0.8 wt% zinc stearate lubricant (such as bio-based zinc stearate GreenZinc™), 0.5 wt% organophosphate nucleating agent (such as pentaerythritol bisphosphate), and 0.4 wt% low molecular weight polycaprolactone were added, wherein the low molecular weight polycaprolactone is used as a flow aid in this invention. After all raw materials were mixed evenly, they were dried at 65°C for 8 hours.

[0031] The ultrasonic micro-injection molding process uses dried raw materials to process the nozzle. The ultrasonic injection process parameters are set as follows: injection temperature 180℃, injection pressure 80 MPa, ultrasonic power 400 W, injection time 10 seconds, and mold cooling time 15 seconds.

[0032] In the above preparation method, the anti-hydrolysis aid is: Example 1-1: 1 wt% dibutyltin dilaurate (DBTL); Examples 1-2: 2 wt% γ-aminopropyltriethoxysilane (APTES); Examples 1-3: 3wt% of a compound, which is composed of triphenyl phosphate (TPP) and diethyltin dilaurate (DETDH) in a mass ratio of 8:2.

[0033] The nozzle obtained in the above embodiments has a smooth surface and no obvious defects when viewed from the outside.

[0034] Comparative Examples 1, 2 Comparative Example 1: Polylactic acid (PLA) and polybutylene succinate (PBS) were mixed at a weight ratio of 5:5 without the addition of any additives. The subsequent raw material drying and processing conditions were the same as those in the above examples.

[0035] From an external perspective, the nozzle obtained in Comparative Example 1 has poor structural integrity after molding, exhibits obvious brittleness, and lacks thermal stability.

[0036] Comparative Example 2: Polylactic acid (PLA) and polybutylene succinate (PBS) were mixed in a weight ratio of 5:5. Based on the total weight of the mixture, additives other than anti-hydrolysis additives were added. The subsequent raw material drying and processing molding processes and conditions were the same as those in the above examples.

[0037] From an external perspective, the nozzle obtained in Comparative Example 2 showed improved structural integrity compared to Comparative Example 1, with reduced surface defects and brittleness. However, significant shrinkage deformation still existed, and its heat resistance and sealing performance did not reach ideal levels, resulting in overall performance that was still insufficient.

[0038] To verify the effects of anti-hydrolysis additives on the degradation performance, durability, and heat resistance of materials, it is recommended to add a comparative example without anti-hydrolysis additives (while keeping other additives added). Please supplement the appearance of the nozzles and the table data obtained from comparative example 2 ↓.

[0039] The performance test results are shown in the table below:

[0040] The above experimental comparison shows that the use of anti-hydrolysis additives can make the nozzle have better heat resistance (compared to Comparative Example 1, the nozzle did not deform significantly after being soaked in hot water), the drip rate of the nozzle was reduced by nearly 100 times, the degradation performance of the nozzle was improved by 13%-15% (compared to Comparative Example 1), and the durability performance was improved by 32%-37% (compared to Comparative Example 1).

[0041] Mechanism Explanation: In Examples 1-1, dibutyltin dilaurate (DBTL) was used as an anti-hydrolysis agent. DBTL is an organotin stabilizer that can undergo a complexation reaction with the carboxyl groups or hydrolysis products at the ends of polyester molecules, thereby improving the compatibility of the PLA / PBS system. The complexation reaction neutralizes the acidic substances in the hydrolysis process, which can delay the main chain breakage, thereby forming a thermally stable structure and improving the product's heat resistance, degradation resistance, and durability. Other organotin stabilizers, such as dibutyltin octanoate, can also be used as anti-hydrolysis agents because they have similar reaction principles. Examples 1-2 use γ-aminopropyltriethoxysilane (APTES) as an anti-hydrolysis agent. APTES is a silane coupling agent that can condense with polar functional groups within the material to form a dense Si-O-Si network structure, effectively preventing moisture diffusion. Therefore, it can improve the material's thermal stability, heat resistance, degradation resistance, and durability. Of course, other silane coupling agents also have the same effect. Examples 1-3 use a compound of triphenyl phosphate (TPP) and diethyltin dilaurate (DETDH). By capturing free radicals and hydrolysis-induced oxidation products, it synergistically stabilizes the polymer backbone, improving the material's durability in humid and hot environments.

[0042] (II) The Influence of Injection Molding Conditions on Nozzle Performance Traditional injection molding processes are difficult to adapt to thermosensitive biodegradable materials in terms of heating process and mold cavity structure control, easily leading to problems such as thermal decomposition, poor flowability, and low dimensional accuracy of the finished products. This invention verifies the feasibility of micro-injection molding in the processing of thermosensitive biodegradable materials. Testing shows that the key to processing thermosensitive biodegradable materials is the use of ultrasound during the injection stage and rapid cooling and demolding of the mold cavity.

[0043] Example 2-1: Based on Example 1-1, keeping other conditions unchanged, the ultrasonic injection molding process parameters are adjusted as follows: injection temperature 160℃, injection pressure 70 MPa, ultrasonic power 200 W, injection time 10 seconds, mold cooling time 15 seconds; Example 2-2: Based on Example 1-1, keeping other conditions unchanged, the ultrasonic injection molding process parameters are adjusted as follows: injection temperature 220℃, injection pressure 90 MPa, ultrasonic power 600 W, injection time 10 seconds, and mold cooling time 15 seconds.

[0044] As can be seen from Examples 1-1, 2-1, and 2-2, under the conditions of injection temperature of 160-220℃, injection pressure of 70-90MPa, and ultrasonic power of 200-600W, injection for 10 seconds and rapid cooling and demolding within 15 seconds can produce a nozzle with complete appearance, accurate dimensions, and high sealing performance.

[0045] Comparative Example 3: It is recommended to add a comparative example processed by traditional injection molding process. The main differences lie in the appearance integrity, dimensional accuracy and sealing performance of the nozzle.

[0046] Comparative Example 3: Comparative Example 3, based on Examples 1-1, kept other conditions unchanged and adjusted the traditional injection molding process parameters as follows: injection temperature 180℃, injection pressure 80 MPa, injection time 10 seconds, and mold cooling time 15 seconds.

[0047] The preparation conditions of Comparative Example 3 were traditional injection molding processes. Due to insufficient melt fluidity, flow marks and bubbles appeared on the surface, the structure shrank significantly, some thin-walled areas were not fully filled, the dimensional error was large, the sealing performance was poor, and it was difficult to obtain a nozzle with a complete appearance, accurate dimensions and excellent sealing performance.

[0048] Mechanism explanation: Introducing ultrasound during the injection stage can not only effectively reduce the risk of thermal degradation of materials, thus improving thermal stability, but also significantly improve the fluidity and dispersion of the melt, which is conducive to the uniform distribution of multi-component modified systems and the processing and molding of the nozzle. In addition, the instantaneous vibration of the ultrasonic waves on the inner wall of the mold cavity also helps to demold the molding interface, improve structural accuracy and product surface quality. Moreover, the rapid cooling and shaping in 15 seconds can meet the high requirements of the nozzle for dimensional accuracy and sealing performance.

[0049] (III) Effects of PLA / PBS ratio and flexible modification additives on the mechanical properties of the nozzle This invention also verified the effect of the PLA / PBS ratio on the mechanical properties of the material. Elongation at break and tensile strength are two key parameters for evaluating the mechanical properties of the nozzle. Elongation at break is one of the important indicators for evaluating the mechanical properties of the nozzle; a high elongation at break indicates good flexibility / ductility, making it less prone to cracking due to compression or stretching during use or transportation. Tensile strength is another important indicator for evaluating the mechanical properties of the nozzle; high tensile strength indicates strong load-bearing capacity and a stable overall structure.

[0050] Polylactic acid (PLA) and polybutylene succinate (PBS) were mixed in a certain proportion, with the auxiliary agent formulation and proportion remaining consistent. 10 wt% polycaprolactone (PCL), 2.5 wt% dibutyltin dilaurate (DBTL), 0.8 wt% zinc stearate lubricant (such as bio-based zinc stearate GreenZinc™), 0.5 wt% organophosphate nucleating agent (such as pentaerythritol bisphosphate), and 0.4 wt% low molecular weight polycaprolactone were added. The mixed raw materials were dried at 65°C for 8 hours.

[0051] The ultrasonic injection molding process was adopted, with the following parameters set: injection temperature 180℃, injection pressure 80 MPa, ultrasonic power 400 W, injection time 10 seconds, and mold cooling time 15 seconds. The mold is equipped with venting grooves and a uniformly distributed water cooling system to ensure heat exchange efficiency and product quality.

[0052] Examples 3-1, 3-2, 3-3: Example 3-1: The mass ratio of PLA / PBS was 8:2; Example 3-2: The mass ratio of PLA / PBS was 5:5; Example 3-3: The mass ratio of PLA / PBS is 3:7.

[0053] Comparative Examples 4, 5, 6, 7: Comparative Example 4: 100% PLA material was used, without adding any additives. The raw material drying and injection molding parameters were the same as in Example 3-1. The nozzles processed in Comparative Example 4 showed brittleness and poor structural integrity.

[0054] Comparative Example 5: Using 100% PBS material without adding any additives, the raw material drying and injection molding parameters were the same as in Example 3-1; the nozzles processed in Comparative Example 5 showed significant surface shrinkage and insufficient heat resistance.

[0055] Comparative Example 6: PLA / PBS were mixed in a weight ratio of 5:5 without the addition of other additives. The raw material drying and injection molding parameters were the same as those in Example 3-1. The nozzles processed in Comparative Example 6 had poor structural integrity after molding, with obvious brittleness and insufficient hydrolysis resistance, resulting in poor overall performance.

[0056] Comparative Example 7: PLA / PBS were mixed in a 5:5 weight ratio, with 10 wt% polycaprolactone (PCL) added. No other additives were added. The raw material drying and injection molding parameters were the same as in Examples 3-1. The nozzle processed in Comparative Example 7 had a relatively intact structure after molding, without obvious brittleness, but its dimensional stability and durability were still insufficient, resulting in poor overall performance. Please provide details on the product's appearance and performance. This comparative example mainly verifies the effect of the flexible modifier on the nozzle's performance, especially its mechanical properties.

[0057] The performance test results are shown in the table below:

[0058] As shown in the table above, compared to pure PLA and pure PBS materials, the tensile strength and elongation at break properties of the PLA / PBS blend are harmonized. With increasing PBS content, the elongation at break increases while the tensile strength decreases. This makes it more suitable for the mechanical performance requirements of the nozzle, as the improved mechanical properties adjust the nozzle's heat resistance, sealing performance, degradation rate, and durability. In contrast, Comparative Examples 4 and 5 have relatively extreme properties and are unsuitable for nozzle manufacturing. Comparative Example 4, although possessing a high tensile strength of 34 MPa, has an elongation at break of only 6%, indicating high brittleness and a tendency to crack. Comparative Example 5, while having an elongation at break of 120%, has a low tensile strength of only 18 MPa, indicating weak support and structural instability. Although Comparative Example 6 is a PLA / PBS blend, its performance is not yet optimal.

Claims

1. A biodegradable and environmentally friendly mouthpiece based on PLA / PBS composite material and its preparation method, wherein the raw materials for processing the mouthpiece include: Polylactic acid, polybutylene succinate, flexible modification aid, anti-hydrolysis aid; the anti-hydrolysis aid is selected from the group consisting of organic tin stabilizer, silane coupling agent, triphenyl phosphate and diethyl tin dilaurate complex.

2. The degradable environment-friendly mouthpiece based on PLA / PBS composite material and the preparation method thereof according to claim 1, characterized in that, The organic tin stabilizer includes dibutyl tin dilaurate and dibutyl tin octoate; the silane coupling agent includes gamma-aminopropyl triethoxysilane. 3.The PLA / PBS composite material-based degradable environment-friendly mouthpiece according to claim 1, characterized in that, The mass ratio of polylactic acid to polybutylene succinate is 3:7-8:

2. 4.The PLA / PBS composite material-based degradable environment-friendly mouthpiece according to claim 1, wherein, The flexible modification aid includes thermoplastic polyurethane and polycaprolactone. 5.The PLA / PBS composite material-based degradable environment-friendly mouthpiece according to claim 1, wherein, The nozzle processing raw material further includes lubricant, nucleating agent and flow aid. 6.The PLA / PBS composite material-based degradable environment-friendly mouthpiece according to claim 5, characterized in that, The lubricant is zinc stearate lubricant, the nucleating agent is organic phosphate nucleating agent, and the flow aid is low molecular weight polycaprolactone. 7.The PLA / PBS composite material-based degradable environment-friendly mouthpiece according to claim 6, characterized in that, Based on the total mass of polylactic acid and polybutylene succinate, the addition amount of the lubricant is 0.8wt%, the addition amount of the nucleating agent is 0.5wt%, and the addition amount of the flow aid is 0.4wt%. 8.The PLA / PBS composite material-based degradable environment-friendly mouthpiece according to claim 1, wherein, The weight ratio of triphenyl phosphate to diethyl tin dilaurate is 8:

2. 9.The PLA / PBS composite material-based degradable environment-friendly mouthpiece of claim 1 or the preparation method thereof. The addition amount of the anti-hydrolysis aid is 1-3wt% of the total mass of polylactic acid and polybutylene succinate; the addition amount of the flexible modification aid is 5-20wt% of the total mass of polylactic acid and polybutylene succinate. 10.The PLA / PBS composite material-based degradable environment-friendly mouthpiece according to claim 1, wherein, The preparation method includes the following steps: all processing raw materials are proportioned, dried at 65℃ for 8h, and then obtained by ultrasonic injection molding and cooling demolding, wherein the parameters of ultrasonic injection molding are set as follows: injection temperature 160-220℃, injection pressure 70-90MPa, mold cooling time 10-20s, and 200-600W power of ultrasonic wave is applied in the injection process to assist melting and mold filling.

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