Modified polyester degradable plastic composition for hot stamping forming and preparation method thereof

Abstract

The invention relates to the technical field of degradable plastic compositions, and discloses a modified polyester degradable plastic composition for hot stamping forming and a preparation method thereof, the modified polyester degradable plastic composition comprises hydroxyl-terminated hyperbranched polyester, organic modified montmorillonite, an antioxidant and a polyester matrix composed of polylactic acid and poly (butylene succinate), the interface adsorption effect of terminal hydroxyl of terminal hydroxyl hyperbranched polyester and edge active silicon hydroxyl of organic modified montmorillonite is utilized, and a thermal response dispersion phase structure is constructed in a polyester matrix; when hot stamping is heated, hydroxyl-terminated hyperbranched polyester is separated from a montmorillonite sheet layer and migrates and enriches towards the surface, a molecular slippage layer is formed on a hot stamping interface, the physical contradiction between hot-state adhesion and cold-state fracture is solved in a coordinated mode, a controlled release mechanism of interface components is utilized, precise cutting of the hot stamping interface is achieved on the premise that the impact toughness of the material is maintained, and the hot stamping performance is improved. Burrs on the edge of the pattern are inhibited, and the resolution of the hot stamping pattern is improved.

Description

Technical Field

[0001] This invention relates to a modified polyester biodegradable plastic composition for hot stamping and its preparation method, belonging to the technical field of biodegradable plastic compositions. Background Technology

[0002] Current hot stamping processes require the composition to have melt adhesion upon heating to ensure a firm bond between the pattern and the substrate; at the same time, the hot stamping layer must have a tendency to fracture brittlely upon cooling and release to cut off the edges of the pattern.

[0003] Existing hot stamping hardware solutions focus on optimizing heat source distribution and roller shape, but the heat conduction control methods also lack specificity. For example, the utility model patent with authorization announcement number CN207373919U discloses a hot stamping device that drives multiple hot stamping heads to work collaboratively through a single heat source. Although this improves the efficiency of mechanical operation, the control logic is still limited to overall pressure conduction and cannot induce transient responses in the molecular chain segments inside the biodegradable polyester. This results in the release component being unable to migrate directionally to the interface within an extremely short heat pulse. Existing technologies improve this by adding inorganic fillers. The edge shearing sensation during release, or the addition of low molecular weight lubricating components to adjust the release performance, however, the hot stamping process is usually in a state of millisecond-level pulse power output. The rearrangement speed of polyester macromolecular chain segments and the crystal domain construction speed are difficult to match the transient thermal field. A large amount of inorganic filler degrades the mechanical properties of the hot stamping layer, leading to the risk of pattern cracking. Low molecular weight components are randomly distributed throughout the composition in the entire time domain, making it difficult to migrate directionally to the interface within an extremely short thermal pulse. This physical mismatch between the entire time domain distribution and the instantaneous requirements causes a logical coupling between hot adhesion and cold breakage.

[0004] Therefore, the technical problem to be solved by this invention is how to achieve the transient construction of the release interface and the precise cutting of the pattern edge during the hot stamping process while maintaining the overall toughness of the polyester composition. Summary of the Invention

[0005] To address the problems mentioned in the background art, the technical solution of the present invention is as follows: A modified polyester biodegradable plastic composition for hot stamping, comprising the following components by weight percentage:

[0006] Hydroxyl-terminated hyperbranched polyester, content ranging from 2.0% to 8.0%; organically modified montmorillonite, content ranging from 1.0% to 5.0%; antioxidant, content ranging from 0.1% to 0.5%; polyester matrix, content in balance;

[0007] The polyester matrix is ​​composed of polylactic acid and polybutylene succinate in a mass ratio of 3:1 to 5:1, and the polylactic acid is at 190... And the melt index at a load of 2.16 kg is 5 to 8 g / 10 min, and the polybutylene succinate at 190 And the melt flow index at a load of 2.16 kg is 2 to 4 g / 10 min;

[0008] The hydroxyl-terminated hyperbranched polyesters have hydroxyl values ​​of 300 to 350 mg KOH / g, and the hydroxyl-terminated hyperbranched polyesters have a hydroxyl value of 150 mg KOH / g. The melt viscosity is below 2 Pa·s;

[0009] The interlayer spacing of the organically modified montmorillonite is 2.5 to 3.5 nm, and the edges of the organically modified montmorillonite lamellae have active silanol groups.

[0010] Hydroxyl-terminated hyperbranched polyesters form a thermoresponsive dispersed phase structure in the polyester matrix by interfacial adsorption between their terminal hydroxyl groups and the active silanol groups of organically modified montmorillonite.

[0011] Thermally responsive dispersed phase structure at 120 Up to 160 Under the heated state of the hot stamping, the terminal hydroxyl hyperbranched polyester is released due to the weakening of the interfacial adsorption. The released terminal hydroxyl hyperbranched polyester migrates to the surface of the composition and accumulates to form a slip layer with a thickness of 100 to 500 nm at the hot stamping interface.

[0012] Among them, the hydroxyl-terminated hyperbranched polyester is a polyester polyol with a spherical topology obtained by polycondensation of 2,2-dimethylolpropionic acid with trimethylolpropane as the initiator, and its number average molecular weight is 2,000 to 5,000, and its glass transition temperature is 35°C to 50°C.

[0013] The composition meets the following proportioning rules: ,in, This is the phase structure stability factor, and its value ranges from 1.5 to 3.0; The weight percentage of hydroxyl-terminated hyperbranched polyester in the composition; The weight percentage of organically modified montmorillonite in the composition.

[0014] Preferably, the weight-average molecular weight of polylactic acid is 150,000 to 200,000; the crystallinity of polybutylene succinate is 30% to 45%; in the polyester matrix, the sum of the masses of polylactic acid and polybutylene succinate accounts for more than 95% of the total mass of the polyester matrix, and the polyester matrix is ​​within 190... The melt strength is not less than 0.2N.

[0015] Preferably, the organically modified montmorillonite is prepared by ion exchange modification of sodium montmorillonite with octadecyltrimethylammonium chloride, wherein the weight percentage content of the organic modifier is 30% to 40%; and the sheet thickness of the organically modified montmorillonite is 1 to 10 nm.

[0016] Preferably, the antioxidant is composed of hindered phenolic antioxidant 1010 and phosphite antioxidant 168 in a mass ratio of 1:1 to 1:2.

[0017] Preferably, the organically modified montmorillonite is distributed in a discrete, exfoliated state within the polyester matrix; and in the cross-section of the composition, the average number of organically modified montmorillonite lamellar particles per unit area is not less than 50 particles / μm².

[0018] Preferably, the composition is at 190 The overall melt flow index at a load of 2.16 kg is 4 to 7 g / 10 min; the elongation at break of the composition is 10% to 30%; and its notched impact strength is not less than 5 kJ / m².

[0019] Preferably, the slip layer is at 150 The shear cohesive strength at that time was less than 10% of the melt strength of the polyester matrix; the dynamic contact angle formed by the slip layer on the surface of the composition was reduced by 15° to 30° relative to the dynamic contact angle of the composition body; the thickness of the hot stamping layer after the composition was formed by hot stamping aluminum foil process was 10 to 30 μm; the hot stamping layer at 25 The adhesion level in the environment reaches level 0, and the burr width at the edge of the pattern is less than 0.05mm.

[0020] A method for preparing a modified polyester biodegradable plastic composition for hot stamping includes the following steps:

[0021] Step S1101: The polyester matrix, organically modified montmorillonite, and hydroxyl-terminated hyperbranched polyester are respectively subjected to 60°C. Up to 80 The components are dehydrated and dried for 4 to 10 hours to reduce the moisture content of each component to less than 0.05% by weight.

[0022] Step S1102: Add the dried components and antioxidants to a high-speed mixer and premix for 5 to 15 minutes at a speed of 500 to 800 rpm to obtain a uniformly distributed premix.

[0023] Step S1103: Add the premixed material to a co-rotating twin-screw extruder with a length-to-diameter ratio of 40:1 to 48:1, and set the temperature of each zone of the extruder to 160°C. Up to 195 The screw speed is controlled to be 200 to 450 rpm; the shear force field generated by the screw configuration induces the terminal hydroxyl groups of the hyperbranched polyester to undergo interfacial adsorption with the active silanol groups of the organically modified montmorillonite, so as to construct a thermally responsive dispersed phase structure in the molten polyester matrix.

[0024] Step S1104 involves cooling, air-drying, and pelletizing the material extruded from the extruder head in a constant temperature water bath to obtain a modified polyester biodegradable plastic composition for hot stamping.

[0025] Compared with the prior art, the beneficial effects of the present invention are:

[0026] 1. In modified polyester biodegradable plastic compositions, thermosensitive hybrid microdomains are constructed by using hydroxyl-terminated hyperbranched polyester and modified montmorillonite. Hydrogen bonding is used to physically lock the regulating components at the edge of the amorphous region of the polyester matrix. This static locking mechanism avoids low molecular weight components from interfering with the effective entanglement of polyester macromolecular chains at room temperature, maintaining the overall impact toughness of the composition. When triggered by a thermal pulse, the hydrogen bonds undergo reversible breakage, and the released hyperbranched molecules are directionally pumped to the mold interface using the repulsive entropy generated by their topological structure. This achieves molecular-level precise cutting of the interface while maintaining the strength of the matrix, solving the problem of mechanical property degradation caused by the full-time-domain free release of release components in traditional modified materials.

[0027] 2. By controlling the branching degree and melt viscosity of hyperbranched molecules, this invention forms a continuous and uniformly thick low-cohesion slip layer at the interface, which tends to fracture brittlely upon cooling. This ensures that the edges of the pattern are cleanly cut while the hot stamping layer retains excellent flexibility. When the product is subjected to bending or impact, the hot stamping pattern is firmly bonded to the substrate, avoiding peeling or micro-cracks. This solves the technical contradiction between molding quality and reliability caused by the addition of brittle fillers to biodegradable materials.

[0028] 3. By using a non-equilibrium cooling process to freeze hybrid microdomains in a specific phase region of the polyester matrix, the controlled transformation of the surface phase state throughout the material's entire life cycle is achieved. This allows the regulating factor to remain inert during the processing and storage stages, only physically detaching and exercising its slip function at a specific hot stamping threshold temperature. This non-linear time axis control of the release function improves hot stamping accuracy while ensuring the material's storage stability and processing window, thus broadening the application boundaries of biodegradable polyester in the high-end precision decoration field. Attached Figure Description

[0029] Figure 1 This is a schematic diagram illustrating the heat release mechanism of the thermally responsive dispersed phase structure of the present invention and the construction process of the slip layer at the hot stamping interface;

[0030] Figure 2 This is a panoramic view of the technical system composition, surface mechanism, and preparation process of the modified polyester biodegradable plastic composition of the present invention. Detailed Implementation

[0031] To enable those skilled in the art to better understand the technical solutions of the present invention, 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; the following embodiments are only used to explain the present invention and do not constitute a limitation on the scope of protection of the present invention; on this basis, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0032] This invention provides a modified polyester biodegradable plastic composition for hot stamping and its preparation method. By constructing a thermoresponsive dispersed phase structure in the polyester matrix, the contradiction between hot adhesion and cold fracture is resolved, achieving interface severance while maintaining impact toughness. The modified polyester biodegradable plastic composition for hot stamping comprises the following components by weight percentage: hydroxyl-terminated hyperbranched polyester, with a content of [missing information]. to Organically modified montmorillonite, with a content of to Antioxidant, content is to Polyester matrix, content is in the balance; the polyester matrix is ​​composed of polylactic acid and polybutylene succinate in a certain mass ratio. to Composition; polylactic acid in and Melt flow index at kg load is to g / 10min, its weight-average molecular weight is to Polybutylene succinate in and Melt flow index at kg load is to g / 10min, its crystallinity is to In the polyester matrix, the sum of the masses of polylactic acid and polybutylene succinate accounts for [percentage]% of the total mass of the polyester matrix. The above describes the polyester matrix in... The melt strength below is not less than N; Hydroxyl-terminated hyperbranched polyester is a product initiated with trimethylolpropane and composed of... - A polyester polyol with a spherical topology obtained by polycondensation of dimethylolpropionic acid; the hydroxyl value of the hydroxyl-terminated hyperbranched polyester is... to mgKOH / g, and hydroxyl-terminated hyperbranched polyester in The melt viscosity is lower than Pa·s; the number average molecular weight of hydroxyl-terminated hyperbranched polyester is to And its glass transition temperature is to Organically modified montmorillonite was prepared by ion exchange modification of sodium-based montmorillonite with octadecyltrimethylammonium chloride, wherein the weight percentage of the organic modifier was [missing information]. to The interlayer spacing of organically modified montmorillonite is to nm, its sheet thickness is to nm, and the edges of the organically modified montmorillonite lamellae have active silanol groups.

[0033] The hydroxyl-terminated hyperbranched polyester forms a thermoresponsive dispersed phase structure within the polyester matrix through interfacial adsorption between its terminal hydroxyl groups and the active silanol groups of organically modified montmorillonite. The composition satisfies the following formulation rules: ,in, The phase structure stability factor has a value range of . to ; The weight percentage of hydroxyl-terminated hyperbranched polyester in the composition; The percentage of organically modified montmorillonite in the composition; when the density of active sites fluctuates in the batch of raw materials, the density of terminal hydroxyl groups in the hyperbranched polyester is determined using Fourier transform infrared spectroscopy. The density of edge-active silanol groups in organically modified montmorillonite was determined by silane coupling agent titration. ,according to and Molar coordination ratio adjustment of end-hydroxyl hyperbranched polyester weight percentage Percentage by weight of organically modified montmorillonite Feed ratio affects the phase structure stability factor. Maintaining within the 1.5 to 3.0 range, utilizing and The formation of interfacial hydrogen bonds allows for the locking and regulation of components at 120°C. Up to 160 Triggered release behavior at hot stamping temperature; thermally responsive dispersed phase structure in to Under heated conditions, the hot stamping process releases terminal hydroxyl hyperbranched polyester due to weakened interfacial adsorption. The released terminal hydroxyl hyperbranched polyester migrates and accumulates on the surface of the composition, forming a layer with a thickness of [thickness value missing] at the hot stamping interface. to A slip layer of nm; the slip layer in The shear cohesive strength at that time was lower than the melt strength of the polyester matrix. The dynamic contact angle formed by the slip layer on the composition surface is reduced relative to the dynamic contact angle of the composition body. ° to °.

[0034] The enrichment effect of interfacial components after the composition is subjected to pressure and heat was identified using differential scanning calorimetry to pinpoint the onset point of the desorption endothermic peak in the enthalpy curve, thus determining the critical desorption temperature at which the terminal hydroxyl hyperbranched polyester detaches from the organically modified montmorillonite sheets. The dynamics of slip layer construction were observed by varying the duration of the heating pulse at 120°C. Up to 160 Under heat, the hydroxyl-terminated hyperbranched polyester releases channels along the exfoliated montmorillonite sheets and migrates to the hot stamping interface, forming a molecular slip layer with a thickness of 100 to 500 nm and a shear cohesive strength 10% lower than the melt strength of the polyester matrix. This slip layer reduces the shear resistance between the hot stamping layer and the mold interface, and precisely severs the pattern edges upon cooling and peeling. The antioxidant is a hindered phenolic antioxidant. With phosphite antioxidants By mass ratio to Mixed composition, composition in and The overall melt flow index at a kg load is to g / 10min; the elongation at break of the composition is to Its simply supported beam notched impact strength is not less than kJ / m²; The organically modified montmorillonite is distributed in a discrete, exfoliated state within the polyester matrix. In the cross-section of the composition, the average number of organically modified montmorillonite lamellar particles per unit area is not less than [amount missing]. μm².

[0035] The preparation method of the modified polyester biodegradable plastic composition for hot stamping includes the following steps: Step S1101, the polyester matrix, organic modified montmorillonite, and hydroxyl-terminated hyperbranched polyester are respectively... to The following is a dehydration and drying process. h to h, so that the moisture content of each component is lower than Weight percentage; Step S1102, add the dried components and antioxidant to a high-speed mixer according to the above weight percentages, and... to Premixing at rpm min to min, to obtain a uniformly distributed premix; step S1103, add the premix to a length-to-diameter ratio of to In a co-rotating twin-screw extruder, the temperature of each zone of the extruder is set to... to The screw speed is controlled to be to The shear force field generated by the screw configuration induces interfacial adsorption between the terminal hydroxyl groups of the hyperbranched polyester and the active silanol groups of the organically modified montmorillonite, constructing a thermally responsive dispersed phase structure in the molten polyester matrix. In step S1103 melt extrusion, three sets of kneading block units with a 45° stagger angle are selected from the screw combination of the co-rotating twin-screw extruder, and the screw speed is adjusted to generate 800 to 1200 rpm. Shear rate The mechanical shear field was used to induce the discrete exfoliation of organically modified montmorillonite in a polyester matrix, and the output power of the drive motor was monitored. With total material flow Real-time calculation of specific mechanical energy , When the deviation from the benchmark value is 0.18 to 0.22 kWh / kg, adjust the heat power output of the third to fifth temperature zones of the extruder and correct the screw speed to ensure that the terminal hydroxyl hyperbranched polyester is uniformly wetted and adsorbed on the surface of the organically modified montmorillonite flakes, forming an average flake particle number of not less than 50 / μm² in the cross-sectional area. In step S1104, the material extruded from the extruder die head is cooled in a constant temperature water bath, air-dried, and pelletized to obtain a modified polyester biodegradable plastic composition for hot stamping. The thickness of the hot stamping layer after hot stamping aluminum foil is [missing information]. to μm, hot stamping layer in Adhesion level in the environment reaches Level, and the width of the burrs on the edge of its pattern is less than mm.

[0036] Example 1: At an operating frequency of On a high-speed automatic hot stamping line operating at times / min, hot stamping is performed on complex curved packaging shells with geometric textures. The duration of the heat pulse applied by the hot stamping head is [duration missing]. s; When using conventional polyester materials without the thermally responsive dispersed phase structure of this invention, serrated cracks are generated at the edge of the hot stamping layer under the action of peeling force, and due to the uneven distribution of the slip layer thickness at the interface, the width of the burrs at the edge of the hot stamping pattern reaches mm; A modified polyester biodegradable plastic composition for hot stamping was obtained using the preparation method of this invention, wherein the mass ratio of polylactic acid to polybutylene succinate in the polyester matrix was selected as follows: The weight percentage content of hydroxyl-terminated hyperbranched polyester is: The weight percentage content of organically modified montmorillonite is: In this state, the active hydroxyl groups at the ends of the hydroxyl-terminated hyperbranched polyester undergo hydrogen bond adsorption with the active silanol groups at the edges of the organically modified montmorillonite sheets; this effect locks the hydroxyl-terminated hyperbranched polyester within the amorphous segments of the polyester matrix at room temperature; the composition in this state satisfies the following calculation formula: ,in, The phase structure stability factor is, in this embodiment, its value is . , The weight percentage of hydroxyl-terminated hyperbranched polyester in the composition. The weight percentage of organically modified montmorillonite in the composition.

[0037] When the hot stamping equipment applies a temperature to the composition, Under transient thermal conditions, the adsorption energy between the hydroxyl-terminated hyperbranched polyester and the organically modified montmorillonite decreases below the desorption threshold as the temperature rises, causing the hydroxyl-terminated hyperbranched polyester to detach from the lamellar surface of the organically modified montmorillonite. The desorbed hydroxyl-terminated hyperbranched polyester, due to its lower adsorption energy than the organically modified montmorillonite, exhibits the following effect: The melt viscosity, Pa·s, migrates along the microchannels constructed by the exfoliated montmorillonite sheets towards the heated interface. s forms a thickness of on the surface of the composition. A nm-sized slip layer reduces the shear resistance between the hot stamping layer and the mold interface, allowing the hot stamping pattern to be precisely cut along the pressure edge during cooling and peeling; the adhesion level of the hot stamping pattern obtained by testing is [insert value here]. Grade, edge burr width is mm, and the notched impact strength of the simply supported beam of the material remains at kJ / m²; The composition achieves physical pinning of the modulating components in the storage state through the dynamic conversion of adsorption energy in the thermally responsive dispersed phase structure, and meets the requirements for the construction speed of the interface slip layer under the transient heating during processing.

[0038] Example 2: On a hot stamping molding test platform equipped with dynamic thermodynamic monitoring capabilities, the phase structure stability factor was verified by setting different component ratio gradients. The experiment aimed to determine the regulatory effect on the resolution of hot stamping patterns and the impact toughness of materials. The purpose of the experiment was to establish the optimal ratio between hydroxyl-terminated hyperbranched polyester and organically modified montmorillonite, and its influence on the interfacial slip layer construction dynamics under millisecond-level thermal pulse excitation. The experimental data were obtained from a physical experimental system consisting of a hot-pressing unit and an in-situ friction monitoring instrument. Temperature control accuracy, pressure control range is to MPa, and the sampling frequency is set to Hz; the core process parameter in the experiment was the hot stamping pressure. The technical trade-off in setting these parameters lies in ensuring the molecular penetration strength between the hot stamping layer and the substrate, while avoiding lateral pattern overflow caused by excessive pressure; based on the rheological response curve of the polyester matrix in the molten state, the hot stamping temperature... for Under the operating conditions, determine the hot stamping pressure. for MPa; to simulate thermal fluctuations in a real industrial environment, an amplitude of [missing value] was introduced into the heating unit during the experiment. Temperature noise was eliminated, and a median filtering algorithm was used to process the original signal to remove environmental electromagnetic interference. This experiment designed a multi-dimensional control system including an experimental group, a control group, and an out-of-range group to verify the synergistic effect and the deterministic basis of the numerical range of the present invention. The experimental group used the complete composition of the present invention and set... Value Control group A lacked organically modified montmorillonite; control group B lacked terminal hydroxyl hyperbranched polyester and only used conventional inorganic filling technology; the out-of-range group C... The value is set to That is, below the lower limit of the defined range; group D that exceeds the range will... The value is set to That is, higher than the upper limit of the defined range; the test process changed the composition ratio of each sample group and observed the slip layer construction time, pattern edge burr width and material simple beam notch impact strength of each group within the same hot stamping cycle.

[0039] Table 1: Comparison of Hot Stamping Performance and Mechanical Properties under Different Component Distribution States

[0040]

[0041] Refer to the measured data in Table 1. When the composition meets the following conditions... Value According to the design specifications, the slip layer construction time is s, the width of the burrs at the edge of the resulting pattern is mm, showing an improvement in hot stamping precision; the control group A, lacking organically modified montmorillonite, lacked interfacial anchoring centers, leading to aggregation of the regulating components during the storage stage, and increasing the slip layer construction time to mm. s, and the material's notched impact strength in a simply supported beam decreases to due to phase separation. kJ / m²; when Value lower than During the out-of-range group C operation test, the excessive montmorillonite sheets generated a physical steric hindrance effect and excessive adsorption energy, which limited the desorption of the terminal hydroxyl hyperbranched polyester under the transient thermal field, extending the slip layer construction time to [missing information]. s, the burr width increases; when Value exceeds During the out-of-range group D test, although the hot stamping resolution remained at a good level, the insufficient number of adsorption centers weakened the macromolecular chain entanglement of the polyester matrix due to the weakened free hyperbranched molecules, causing the material's impact strength to decrease. kJ / m²; The results of this experiment confirm that, through the synergistic effect of interfacial adsorption between hydroxyl-terminated hyperbranched polyester and organically modified montmorillonite, the composition achieves a thermoresponsive release mechanism, transforming the conflict between hot adhesion and cold fracture into controlled component migration behavior; Experimental data show that when the phase structure stability factor In to Within the working window, the system can construct a molecular slip layer with low cohesive strength in the instantaneous hot stamping process without sacrificing the overall toughness of the material, thereby achieving a substantial improvement in hot stamping accuracy.

[0042] Example 3: This example combines Figures 1 to 2 This describes a modified polyester biodegradable plastic composition for hot stamping and its preparation method, such as... Figure 1 As shown, the polyester matrix composed of PLA and PBS provides the mechanical basis and achieves matrix coating. The antioxidant is a mixture of 1010 and 168 to provide processing stability. Meanwhile, the terminal hydroxyl hyperbranched polyester, as a regulating component, possesses terminal hydroxyl groups. Organically modified montmorillonite, as an adsorbent carrier, possesses active silanol groups. The two interact through hydrogen bonding and shear force field-induced interfacial adsorption, forming a thermally responsive dispersed phase structure within the system. In its physically locked state, it is stable and does not migrate at room temperature; however, at 120°C... Up to 160 In the heat field of the hot stamping, the adsorption is weakened and released, which leads to interfacial desorption and detachment of hyperbranched polyester. Driven by low viscosity flow and repulsion entropy, the polyester migrates and accumulates on the surface, forming a molecular slip layer with a thickness of 100 to 500 nm and low cohesive strength. This ultimately achieves precise cutting of the hot stamping interface, resulting in burr-free, high-resolution, and hot adhesion and cold fracture effects.

[0043] like Figure 2As shown, the modified polyester biodegradable plastic composition system comprises four dimensions: the component system includes a polyester matrix of polylactic acid + polybutylene succinate, 2% to 8% of a hydroxyl-terminated hyperbranched polyester as a regulating component, 1% to 5% of an adsorbent carrier of organically modified montmorillonite, and a composite antioxidant (1010+168) as an additive. The surface phase mechanism involves a core structure of a thermoresponsive dispersed phase, a locking mechanism of interfacial hydrogen bonding adsorption at room temperature, and a triggering condition of a 120 to 160 degree thermal pulse. The process flow is as follows: for component release and surface migration, the preparation process is as follows: step S1 deep dehydration and drying with a moisture content of <0.05%; step S2 high-speed premixing at a speed of 500 to 800 rpm; step S3 reactive extrusion shear-induced adsorption; and step S4 cooling pelletizing and post-treatment. The key performance indicators are specified as follows: in terms of toughness, the notched impact strength is ≥5kJ / m²; in terms of rheology, the melt index is 4 to 7g / 10min; in terms of precision, the burrs on the hot stamping edge are <0.05mm; and the adhesion level reaches 0, meaning no peeling.

[0044] Example 4: When the ambient humidity fluctuates within a certain range to And the ambient temperature is to In dynamic production environments, modified polyester biodegradable plastic compositions used for hot stamping face the risk of moisture-induced molecular chain degradation and fluctuations in the distribution of regulating components. To achieve quantitative control over the structural stability of the thermally responsive dispersed phase, the system employs an interfacial adsorption energy calibration procedure to determine the terminal hydroxyl density of the terminal hydroxyl hyperbranched polyester. and the corresponding surface density of active silanol groups in organically modified montmorillonite ,in for mmol / g for mmol / g, based on stability factor The value of is used to determine the interfacial hydrogen bond density, and differential scanning calorimetry is used to identify the starting point of the desorption endothermic peak in the enthalpy curve to determine the critical desorption temperature. The critical desorption temperature was determined by a lookup table mapping method. Under standard atmospheric pressure, with a terminal hydroxyl density of 6.0 mmol / g as the calibration reference value, the corresponding reference desorption temperature was 120°C. For every 0.1 mmol / g increase in terminal hydroxyl density, the critical desorption temperature increases by 1.5 °C. This linear compensation logic ensures that different batches of hyperbranched polyester can all be processed at 120°C. Up to 160 Precise desorption is achieved within a pulsed thermal field; in this embodiment, by adjusting... Value Make the critical desorption temperature Stable at This allows the physical adsorption energy between the hydroxyl-terminated hyperbranched polyester and the organically modified montmorillonite sheets to be higher than the environmental thermal disturbance kinetic energy at room temperature, thus locking the component distribution during the storage stage.

[0045] In step S1103 of the preparation method, the screw assembly of the co-rotating twin-screw extruder uses three sets of staggered angles. The kneading block unit at ° is adjusted by rotating the screw at a speed of °. rpm produces no less than shear rate of s⁻¹ To overcome the attraction between montmorillonite lamellae and induce exfoliation, the cross-sections of the obtained samples were subjected to liquid nitrogen brittle fracture treatment and then placed under a scanning electron microscope. A threshold-based image analysis program was used to perform digital statistical analysis on the electron microscope images. This program converts the original grayscale image into a binary image. The specific steps are as follows: mapping the grayscale values ​​of the original grayscale image obtained by the scanning electron microscope to an integer range of 0 to 255; setting a global threshold of 128; identifying pixels with grayscale values ​​below this threshold as organically modified montmorillonite, and those above as polyester matrix; performing gradient detection using a 3x3 pixel matrix operator to identify lamellae edges; counting the total number of identified montmorillonite pixels within a 5μm×5μm unit area and dividing by the standard pixel area of ​​a single lamellae to obtain the specific number of lamellae particles; and using an edge detection operator to identify the width of the lamellae within a certain range. nm to The linear characteristic region between nm is analyzed by integral calculation to count the number of closed regions per unit area. In this embodiment, the average number of lamellar particles is determined to be [value missing]. The measured data, per μm², confirms the constructive effect of a strong shear field on the exfoliation distribution of organically modified montmorillonite, enabling the composition to undergo [a process / process]. and Accelerated aging test with relative humidity After h, the spatial distribution fluctuation rate of its hot stamping layer thickness is lower than .

[0046] Example 5: The hydroxyl value of the hydroxyl-terminated hyperbranched polyester is at... to Within the fluctuation range of mgKOH / g, the density of terminal hydroxyl groups was determined by infrared spectroscopy. Surface density of organically modified montmorillonite The specific measurement procedure is as follows: within the scanning range of 4000 to 400 wavenumbers, the characteristic absorption peak of hydroxyl at the position of 3400 wavenumbers is selected, and the peak area value of the peak is obtained by automatic integration using an infrared spectrometer; it is then linearly compared with the pre-calibrated standard sample curve with known hydroxyl content to obtain the millimolecular concentration of hydroxyl in the current batch of raw materials, thereby providing data input for the feeding ratio of the phase structure stability factor.

[0047] against for For material batches with mmol / g, the weight percentage content of terminal hydroxyl hyperbranched polyester was adjusted according to the interfacial hydrogen bond saturated adsorption model. Percentage of organically modified montmorillonite by weight The feeding ratio affects the phase structure stability factor. Maintain at This parameter setting ensures that the interfacial hydrogen bond density meets the lock-in requirement, resulting in a thermally responsive dispersed phase structure in the composition that remains stable at storage temperatures below a certain level. At this time, no component migration occurs; a melt pressure sensor and torque monitoring unit are installed at the outlet of the co-rotating twin-screw extruder. When changes in ambient humidity cause the instantaneous melt viscosity to deviate from the reference value by more than [a certain amount], [the sensor will detect the problem]. At the same time, the controller adjusts the heat power output of the extruder from the third to the fifth temperature zone and corrects the screw speed to adjust the shear rate within the melt field. Stable at The process response near s⁻¹ resulted in uniform wetting of the hydroxyl-terminated hyperbranched polyester on the surface of the organically modified montmorillonite sheets. The average number of sheet particles per unit area in the cross-section of the resulting sample group was [value missing]. The measured value of the edge burr width of the hot stamping pattern is μm². mm.

[0048] Example 6: Interlayer spacing of organically modified montmorillonite due to batch switching of raw materials exist to To maintain the physical stability of the thermally responsive dispersed phase structure under operating conditions fluctuating within the nm range, the system executes an adaptation calibration procedure for the interlayer physical space, utilizing... Online scanning of organically modified montmorillonite using X-ray diffraction. The positions of the diffraction peaks on the crystal planes were determined, and the real-time interlayer spacing was calculated. ,against for For materials of nm, the weight percentage content of terminal hydroxyl hyperbranched polyester is adjusted according to the interfacial hydrogen bond saturated adsorption model. Percentage of organically modified montmorillonite by weight The feeding ratio affects the phase structure stability factor. The calculated value is constant. This establishes the interlayer spacing. The mapping relationship with the packing density of hyperbranched molecules ensures that the coordination ratio of active silanol groups to terminal hydroxyl groups in the organically modified montmorillonite is in a saturated adsorption state, thereby lowering the critical desorption temperature. Locked in To make the composition in No component shift occurs in the following storage environments; during the operation of a co-rotating twin-screw extruder, the preparation system performs specific mechanical energy-based adjustments to address instantaneous melt viscosity fluctuations caused by ambient humidity. The process parameter feedback adjustment procedure monitors the output power of the drive motor. With total material flow To calculate the mechanical energy in real time .

[0049] To achieve process transfer between different equipment specifications, the baseline value of specific mechanical energy is corrected and calibrated based on the screw's length-to-diameter ratio. The calibration formula specifies that the baseline value is 0.20 kWh / kg at a standard length-to-diameter ratio of 40:1. For every 2 units increase in the length-to-diameter ratio, due to the increase in friction length, this baseline value needs to be reduced by 0.01 kWh / kg. This linear scaling logic ensures that sufficient shear energy to induce peeling can be generated on different extruder models. When the specific mechanical energy is observed... Deviation This benchmark value exceeds kWh / kg At the same time, adjust the thermal power output of the extruder's melting section and correct the screw speed to adjust the shear rate within the melting zone. Stable at s⁻¹, using shear force field to induce the exfoliation and distribution of organically modified montmorillonite in a polyester matrix, the average number of lamellar particles per unit area of ​​the obtained sample cross-section was The measured value of the edge burr width of the hot stamping pattern is μm². mm, achieving consistency in hot stamping layer cutting accuracy across different equipment platforms.

[0050] 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 present invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the present invention.

[0051] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention.

Claims

1. A modified polyester biodegradable plastic composition for hot stamping, characterized in that, Includes the following components by weight percentage: Hydroxyl-terminated hyperbranched polyester, content ranging from 2.0% to 8.0%; organically modified montmorillonite, content ranging from 1.0% to 5.0%; antioxidant, content ranging from 0.1% to 0.5%; polyester matrix, content in balance; The polyester matrix is ​​composed of polylactic acid and polybutylene succinate in a mass ratio of 3:1 to 5:1, and the polylactic acid is at 190... And the melt index at a load of 2.16 kg is 5 to 8 g / 10 min, and the polybutylene succinate at 190 And the melt flow index at a load of 2.16 kg is 2 to 4 g / 10 min; The hydroxyl-terminated hyperbranched polyesters have hydroxyl values ​​of 300 to 350 mg KOH / g, and the hydroxyl-terminated hyperbranched polyesters have a hydroxyl value of 150 mg KOH / g. The melt viscosity is below 2 Pa·s; The interlayer spacing of the organically modified montmorillonite is 2.5 to 3.5 nm, and the edges of the organically modified montmorillonite lamellae have active silanol groups. Hydroxyl-terminated hyperbranched polyesters form a thermoresponsive dispersed phase structure in the polyester matrix by interfacial adsorption between their terminal hydroxyl groups and the active silanol groups of organically modified montmorillonite. Thermally responsive dispersed phase structure at 120 Up to 160 Under the heated state of the hot stamping, the terminal hydroxyl hyperbranched polyester is released due to the weakening of the interfacial adsorption. The released terminal hydroxyl hyperbranched polyester migrates to the surface of the composition and accumulates to form a slip layer with a thickness of 100 to 500 nm at the hot stamping interface. Among them, the hydroxyl-terminated hyperbranched polyester is a polyester polyol with a spherical topology obtained by polycondensation of 2,2-dimethylolpropionic acid with trimethylolpropane as the initiator, and its number average molecular weight is 2,000 to 5,000, and its glass transition temperature is 35°C to 50°C. The composition meets the following proportioning rules: ,in, This is the phase structure stability factor, and its value ranges from 1.5 to 3.0; The weight percentage of hydroxyl-terminated hyperbranched polyester in the composition; The weight percentage of organically modified montmorillonite in the composition.

2. The modified polyester biodegradable plastic composition for hot stamping according to claim 1, characterized in that, The weight-average molecular weight of polylactic acid (PLA) is 150,000 to 200,000; the crystallinity of polybutylene succinate (PBS) is 30% to 45%; in the polyester matrix, the sum of the masses of PLA and PBS accounts for more than 95% of the total mass of the polyester matrix, and the polyester matrix is ​​within 190... The melt strength is not less than 0.2N.

3. The modified polyester biodegradable plastic composition for hot stamping according to claim 1, characterized in that, Organically modified montmorillonite is prepared by ion exchange modification of sodium-based montmorillonite with octadecyltrimethylammonium chloride, wherein the weight percentage content of the organic modifier is 30% to 40%; the thickness of the organically modified montmorillonite sheets is 1 to 10 nm.

4. The modified polyester biodegradable plastic composition for hot stamping according to claim 1, characterized in that, The antioxidant is composed of hindered phenolic antioxidant 1010 and phosphite antioxidant 168 in a mass ratio of 1:1 to 1:

2.

5. The modified polyester biodegradable plastic composition for hot stamping according to claim 1, characterized in that, The organically modified montmorillonite is distributed in a discrete, exfoliated state within the polyester matrix; in the cross-section of the composition, the average number of organically modified montmorillonite lamellar particles per unit area is not less than 50 particles / μm².

6. The modified polyester biodegradable plastic composition for hot stamping according to claim 1, characterized in that, The composition at 190 The overall melt flow index at a load of 2.16 kg is 4 to 7 g / 10 min; the elongation at break of the composition is 10% to 30%; and its notched impact strength is not less than 5 kJ / m².

7. The modified polyester biodegradable plastic composition for hot stamping according to claim 1, characterized in that, slip layer at 150 The shear cohesive strength at that time was less than 10% of the melt strength of the polyester matrix; the dynamic contact angle formed by the slip layer on the surface of the composition was reduced by 15° to 30° relative to the dynamic contact angle of the composition body; the thickness of the hot stamping layer after the composition was formed by hot stamping aluminum foil process was 10 to 30 μm; the hot stamping layer at 25 The adhesion level in the environment reaches level 0, and the burr width at the edge of the pattern is less than 0.05mm.

8. A method for preparing a modified polyester biodegradable plastic composition for hot stamping, comprising the method for achieving the modified polyester biodegradable plastic composition for hot stamping as described in claim 1, characterized in that, Includes the following steps: Step S1101: The polyester matrix, organically modified montmorillonite, and hydroxyl-terminated hyperbranched polyester are respectively subjected to 60°C. Up to 80 The components are dehydrated and dried for 4 to 10 hours to reduce the moisture content of each component to less than 0.05% by weight. Step S1102: Add the dried components and antioxidants to a high-speed mixer and premix for 5 to 15 minutes at a speed of 500 to 800 rpm to obtain a uniformly distributed premix. Step S1103: Add the premixed material to a co-rotating twin-screw extruder with a length-to-diameter ratio of 40:1 to 48:1, and set the temperature of each zone of the extruder to 160°C. Up to 195 The screw speed is controlled to be 200 to 450 rpm; the shear force field generated by the screw configuration induces the terminal hydroxyl groups of the hyperbranched polyester to undergo interfacial adsorption with the active silanol groups of the organically modified montmorillonite, so as to construct a thermally responsive dispersed phase structure in the molten polyester matrix. Step S1104 involves cooling, air-drying, and pelletizing the material extruded from the extruder head in a constant temperature water bath to obtain a modified polyester biodegradable plastic composition for hot stamping.

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