Laser-marked pet material and method of making the same

Abstract

The application belongs to the technical field of functional plastics, and particularly relates to a laser marking PET material and a preparation method thereof, which comprises the following steps: (1) special glass fiber preparation; and (2) laser marking PET material preparation. The application improves the compatibility of the special glass fiber in the PET base material, and combines the matching of other components and the optimization of the configuration process, so that the laser marking PET material with good laser marking effect, high temperature resistance, wear resistance and good mechanical properties is obtained.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of functional plastics, and particularly relates to a laser marking PET material and a preparation method thereof. BACKGROUND

[0002] In the fields of high-end electronic appliances, new energy vehicles and precision medical devices, the use of laser marking technology to form permanent, clear and environmentally friendly marks (such as serial numbers, two-dimensional codes and logo authentication information) on product structural parts has become a key process to realize product traceability, anti-counterfeiting and brand value-added. This trend puts high requirements on the laser marking suitability of structural part materials, that is, the material must be sensitive and react violently to a specific wavelength of laser to form a high-contrast mark on the surface. Polyethylene terephthalate (PET) engineering plastic is considered as an ideal substrate due to its excellent comprehensive performance. However, the development of high-performance PET materials specifically for laser marking faces a series of severe technical challenges, the core of which lies in the deep contradiction between laser marking performance and other key performance indicators.

[0003] The primary contradiction lies in the conflict between laser absorption efficiency and intrinsic properties of the material. Pure PET resin has high transmittance and low absorption to common infrared laser, and poor energy conversion efficiency, which leads to the need for high power, slow speed, and shallow and insufficient contrast of the mark. The conventional solution is to add laser-sensitive additives (such as carbon black and zinc oxide), but the addition of these additives, especially the high content required for uniform dispersion, will seriously deteriorate the mechanical properties of the material, resulting in a significant decrease in impact strength and limiting the color of the product to dark colors, which cannot meet the design requirements of light-colored appearance.

[0004] The deeper contradiction lies in the synergy problem of laser marking and flame retardancy, mechanical strength. In order to achieve high flame retardant grade (such as UL94 V-0), a large amount of flame retardant system must be introduced. However, many efficient flame retardants (such as aluminum hydroxide and magnesium hydroxide) are white and have high thermal stability, which seriously reflects or scatters laser energy, greatly interferes with or even shields the laser marking effect, resulting in unclear marks. On the contrary, if the amount of flame retardant is reduced to ensure marking, the flame retardant will inevitably fail. At the same time, the addition of glass fibers to maintain strength forms a complex multiphase system with laser additives and flame retardants in the matrix, which has poor interfacial compatibility and easily causes stress concentration, not only making the material brittle, but also causing the surface of the laser marked mark to be rough and the edges to be uneven, which seriously affects the aesthetics and readability of the mark.

[0005] CN 114891327 A discloses a PET mixed modified material, relates to the technical field of modified materials, and is composed of PET regenerated material, PETS flow agent, PC regenerated material and titanium white, wherein the components are in a mass ratio of 100 parts of PET regenerated material, 8 parts of PETS flow agent, 30 parts of PC regenerated material and 5 parts of titanium white. The application adds PETS flow agent, PC regenerated material and titanium white in addition to the main raw material PET regenerated material in the raw material composition of the application, enhances the fluidity of the molten substance through the addition of PETS flow agent, facilitates the fusion of various materials, enhances the high-temperature resistance and toughness of the mixed material through the addition of PC regenerated material, avoids the problems of easy deformation or brittleness during use, and enhances the laser marking clarity effect through the addition of titanium white, but it cannot solve the problems of brittleness caused by the introduction of glass fibers and the decrease of mechanical properties caused by the addition of additives. SUMMARY

[0006] The application provides a laser marking PET material and a preparation method thereof, aiming to overcome the shortcomings of the prior art, improve the compatibility of special glass fibers in a PET base material, and obtain a laser marking PET material with good laser marking effect, high temperature resistance, wear resistance and good mechanical properties by optimizing the configuration process in combination with the adjustment of other components.

[0007] The technical scheme of the application is as follows:

[0008] A preparation method of a laser marking PET material, according to weight parts, includes the following steps:

[0009] (1) Special glass fiber preparation:

[0010] (1-1) Selecting E glass fiber chopped strands with a length of 3-10 mm as a base material;

[0011] (1-2) Immersing the base material in an ethanol aqueous solution containing 1-3% of vinyl tri(β-methoxyethoxy) silane and 2-5% of brominated epoxy resin E-44 by mass concentration, reacting at 60-80°C for 2-4 hours, and drying to obtain glass fibers with flame-retardant and compatibilizing groups;

[0012] (1-3) High-speed mixing the glass fibers with flame-retardant and compatibilizing groups, 0.5-2% of nano antimony white by mass of the modified glass fibers, and 2-5% of titanate coupling agent by mass of the nano antimony white to obtain special glass fibers;

[0013] (2) Preparation of laser marking PET material:

[0014] (2-1) Take by mass fraction: PET resin 80-120 parts, special glass fiber 10-30 parts, special laser engraving additive 0.5-5 parts, brominated polystyrene powder 0.5-5 parts, micron antimony white 0.1-3 parts, nucleating agent 0.1-3 parts, antioxidant 0.1-2 parts, glow wire additive 0.1-3 parts, auxiliary reagent 0-5 parts;

[0015] (2-2) First stir the brominated polystyrene powder and micron antimony white uniformly to obtain a synergistic flame-retardant premix;

[0016] (2-3) Add the PET resin, synergistic flame-retardant premix, nucleating agent, antioxidant, glow wire additive, and auxiliary reagent into a high-speed mixer, stir uniformly for the second time, then add the special glass fiber, stir uniformly for the third time, then add a twin-screw extruder, extrude and granulate to obtain the laser marking PET material.

[0017] The glass fiber modification step of the scheme is not a simple physical coating, but a chemical grafting through the synergistic effect of silane and brominated epoxy resin in a mild environment of ethanol aqueous solution. After the hydrolysis of vinyl tri(β-methoxyethoxy) silane, the silicon hydroxyl group forms a covalent bond with the surface of the glass fiber, and the ether bond and vinyl group contained therein extend to the solution system; at the same time, the epoxy group of the brominated epoxy resin E-44 undergoes ring-opening reaction at the temperature under the catalysis of the silicon hydroxyl group on the surface of the glass fiber and the weak acidity of the system, and forms a bond with the active end group of the silane or the hydroxyl group on the surface of the glass fiber, thereby anchoring the bromine element firmly on the surface of the fiber in a chemical grafting manner, and constructing a first layer of flame-retardant and compatibilizing interface. The setting of the temperature condition is crucial: if the temperature is too low, the reaction rate is too slow, resulting in insufficient grafting rate, and if the temperature is too high, the solvent is easily evaporated too fast and the resin is easily gelled locally, resulting in uneven coating. The reaction time of 2-4 hours ensures the sufficiency of the reaction under the mild condition. Subsequently, in the dry mixing stage, the surface of the nano antimony white is pretreated with a titanate coupling agent, and the nano antimony white is physically anchored near the interface of the modified glass fiber through high-speed shearing mixing with the modified glass fiber, so as to realize efficient and rapid gas-phase flame retardation during combustion, while avoiding macroscopic aggregation of the nanoparticles in the resin matrix.

[0018] In the matrix composite stage, the process sequence deeply affects the dispersion state of each component and the final performance. The first premixing uniformly mixes brominated polystyrene and micron antimony white, aiming to build a second bromine-antimony synergistic system on a macro scale, overcome the uneven dispersion problem caused by the density and polarity difference between the two, and ensure the flame retardant efficiency; the second mixing preliminarily fuses all components except glass fiber with the resin, so that the raven carving aid realizes high-definition marking through heat-absorbing foaming or color contrast, the nucleating agent improves crystallinity and heat resistance, the glow wire aid improves the anti-ignition property through condensed phase carbonization and heat insulation, etc., so that the small molecule aid is uniformly coated on the surface of the PET particle, providing a uniform dispersion basis for subsequent melt extrusion; the third mixing finally adds special glass fiber, and uses low speed and short time mixing, the core purpose is to protect the length and surface fine structure of the glass fiber - if added too early or sheared at high speed for a long time, the glass fiber will break, lose the reinforcing effect, and cause the surface modification layer to wear, damage the interface synergy that has been built, and finally cause the mechanical properties and flame retardancy of the material to deteriorate significantly.

[0019] The final extrusion granulation process controls the temperature gradient accurately, ensures the full melting of PET and the uniform dispersion of each component, while avoiding resin degradation or bromine-based flame retardant decomposition caused by high temperature. The entire preparation process shows that each process parameter is a response and guarantee for the physical and chemical properties of specific components, and its essence is to realize the synergistic effect of multiple components on macro, micro and nanoscale through fine process control, so that the material finally obtains excellent laser marking property, high flame retardant grade, high glow wire ignition temperature and excellent mechanical properties.

[0020] As preferred, in step (1-2), the volume ratio of ethanol to water in the aqueous ethanol solution is 9-9.5:1.

[0021] As preferred, in step (1-3), the process of high-speed uniform mixing is mixing in a high-speed mixer at 800-1200 rpm for 3-5 minutes.

[0022] A stirring rate of 800-1200 rpm ensures sufficient shear force to overcome the van der Waals forces between nanoparticles, breaking up their soft aggregates and giving these fine antimony white particles enough kinetic energy to effectively penetrate the gaps between glass fiber bundles. Ultimately, they are firmly attached to the microscopic cracks and functional group network on the surface of individual glass fibers through mechanical force. However, this speed setting has a clear upper limit constraint—it must be below the threshold that causes significant mechanical damage to the glass fibers. Excessive speed or mixing time will lead to excessive friction and impact between glass fiber filaments and between the glass fibers and the metal inner wall of the mixer. The result is not only glass fiber breakage and a decrease in aspect ratio (thus severely weakening the reinforcement effect of the final material), but also wear and even peeling off the brominated epoxy resin-silane interface layer constructed in steps (1-2), destroying its compatibilizing and flame-retardant functions. Conversely, if the speed is too low, the shear force is insufficient, failing to achieve sufficient deagglomeration and uniform distribution of the antimony white nanoparticles, potentially leading to uneven adhesion or detachment during subsequent processing. Therefore, a moderate duration of 3-5 minutes represents another delicate balance: it provides the necessary time for the uniform dispersion and adhesion of nanoparticles while minimizing the period during which the glass fiber is subjected to high-intensity mechanical stress, thus protecting the physical integrity and surface chemical structure of the glass fiber while achieving functional modification.

[0023] Preferably, in step (2-1), the laser engraving agent is carbon black and zinc oxide in a mass ratio of 1:0.5-1; the nucleating agent is nano-silica; the antioxidant is antioxidant 1010 and antioxidant 168 compounded in a mass ratio of 1:1-2; the glow wire agent is aluminum hydroxide and zinc borate compounded in a mass ratio of 2:1-1.5; and the auxiliary reagent is one or more of lubricant, anti-hydrolysis agent or ultraviolet absorber.

[0024] The laser engraving additive uses a 1:0.5-1 mass ratio of carbon black and zinc oxide. Its core mechanism lies in constructing a dual-response laser action mode: carbon black, as a highly efficient photothermal conversion agent, rapidly absorbs laser energy to generate high temperatures, leading to localized carbonization and the formation of dark markings; while zinc oxide, as a highly efficient inorganic foaming agent, undergoes thermal decomposition or lattice expansion under the instantaneous high heat of the laser, generating gas and forming a microporous structure on the surface. Through the light-scattering effect, it forms high-contrast light or white markings. This combination overcomes the shortcomings of single carbon black (resulting in monotonous marking colors, only black) or single zinc oxide (resulting in insufficient contrast). By adjusting the ratio, the competitive relationship between carbonization and foaming can be precisely controlled, thus adapting to different laser parameters and achieving the clearest marking effect. Nano-silica is preferred as a nucleating agent because it has an extremely high specific surface area and abundant surface silanol groups, which can provide a large number of heterogeneous nucleation sites for PET molecular chains, significantly improving the crystallization rate and crystallinity. This not only shortens the injection molding cycle and improves production efficiency, but also enhances the dimensional stability, heat distortion temperature and surface hardness of the product by forming a denser crystal structure. This is crucial for electronic structural components that need to withstand high temperatures and maintain dimensional precision.

[0025] The antioxidant system employs a 1:1-2 mass ratio of phenolic antioxidant 1010 (primary antioxidant, chain-terminating type) and phosphite antioxidant 168 (auxiliary antioxidant, hydroperoxide decomposition type). This formulation is based on the classic synergistic stabilization mechanism. 1010 effectively captures free radicals generated during processing and use, interrupting the degradation chain reaction; while 168 decomposes hydroperoxides, preventing their homolytic cleavage and generation of new free radicals, thus slowing down degradation at its source. This ratio of formulation provides full-cycle protection for PET materials during melt processing (high-temperature oxidation) and long-term use (thermo-oxidative aging). An excess or deficiency of either antioxidant will create a weakness in the protective network, accelerating material aging, yellowing, or performance degradation.

[0026] The glow wire additive uses a 2:1-1.5 mass ratio of aluminum hydroxide and zinc borate, and its mechanism of action is the synergistic effect of condensed phase flame retardancy and thermal insulation protection. Aluminum hydroxide undergoes vigorous endothermic decomposition at the high temperature of the glow wire contact (approximately 180-200℃), releasing water vapor to dilute oxygen and cool the matrix. Simultaneously, zinc borate melts and vitrifies at an even higher temperature, forming a dense and robust ceramic-like char layer together with the material's decomposition products. This char layer effectively isolates heat and oxygen from inward transfer and prevents the escape of internal combustible gases, thereby significantly increasing the material's glow wire ignition temperature (GWTl). This ratio ensures an optimal balance between the decomposition cooling effect and the char-forming insulation effect.

[0027] The final auxiliary reagents (lubricants, anti-hydrolysis agents, and UV absorbers) are precise supplements to the processing rheological properties and service life in specific environments. Their addition and selection depend entirely on the final product's application scenario (such as whether weather resistance or hydrolysis resistance is required), reflecting the customizability and application flexibility of this formulation system. All these optimized components and their proportions together constitute a multi-level, multi-mechanism synergistic functional additive system, an indispensable guarantee for achieving the material's final comprehensive performance goals.

[0028] Preferably, during the extrusion granulation process, the screw temperature is controlled in segments at 230-240℃, 240-250℃, 250-260℃, 260-270℃, and 270-280℃, and the screw speed is 150-200 rpm.

[0029] Preferably, the process of first stirring to achieve uniformity in step (2-3) is to mix at 400-600 rpm for 10-20 minutes.

[0030] Preferably, the second mixing process in steps (2-3) involves mixing at 600-800 rpm for 10-15 minutes; the third mixing process involves mixing at 400-600 rpm for 5-8 minutes.

[0031] The core challenge of the first mixing step is resolving the significant physical differences between brominated polystyrene and micronized antimony white to achieve uniform premixing on a macroscopic scale. Brominated polystyrene is an organic polymer powder, lightweight and with a certain degree of viscosity; while micronized antimony white is an inorganic metal oxide, dense and prone to settling. A moderate rotation speed is used to provide sufficient shear force to break up the slight agglomeration of brominated polystyrene, while avoiding excessively high speeds that would cause the lightweight brominated polystyrene to be excessively lifted by the airflow and adhere to the vessel wall, resulting in loss and uneven mixing. A longer mixing time ensures that the two components with vastly different densities can fully penetrate and encapsulate each other under continuous mechanical force, ultimately forming a homogeneous "synergistic flame-retardant premix." This step is fundamental to subsequent flame-retardant efficiency; uneven mixing will lead to localized imbalances in the "bromine-antimony" ratio within the material, severely degrading the overall flame-retardant performance.

[0032] The core challenge of the second mixing process shifts to achieving an initial, uniform distribution of various small-dose additives within the PET resin matrix. This mixing involves PET resin particles of varying sizes and all powdered components (synergistic flame retardant premixes, nucleating agents, antioxidants, glow wire additives, etc.). Higher rotational speeds generate stronger eddies and shear forces, sufficient to lift the fine powdered additives from the gaps between PET particles and, through frequent collisions and friction, uniformly adhere to and embed them into the surface of the PET resin particles. This process provides an ideal "pre-dispersion" state for subsequent melt extrusion, significantly reducing the dispersion burden on the twin-screw extruder and preventing localized performance defects caused by the agglomeration of small components. The appropriate time is the minimum effective duration required to ensure this distribution of a large quantity of material.

[0033] The core challenge of the third mixing step is to protect the integrity of the physical form and surface function of the introduced glass fiber while ensuring its proper function. The complexly modified glass fiber serves as the carrier of its reinforcing effect and interfacial synergistic flame-retardant function, but its physical and chemical structure is quite fragile. Reducing the rotation speed to a moderate level and significantly shortening the mixing time is a strategy of "protective mixing." The goal is simply to gently and initially disperse the glass fiber with the previously mixed material, ensuring a roughly uniform distribution. Excessive rotation speed or excessively long mixing time will generate enormous shear and impact forces, causing the glass fiber to break and even peel off its flame-retardant-compressor functional layer. Therefore, this step must achieve a precise balance between achieving dispersion and protecting the key components.

[0034] Preferably, the particle size of the nano-antimony white in step (1-3) is 20-50 nm; the particle size of the micron-antimony white in step (2-1) is 5-20 μm.

[0035] This solution also proposes a laser-marked PET material prepared by the above method, which can be used in electrical structural components, communication equipment structural components and medical equipment structural components.

[0036] The technical advantages of this invention are reflected in the following aspects:

[0037] 1. Composition: This invention integrates compatibilization and brominated flame retardant functions on the glass fiber surface through chemical grafting of silane and brominated epoxy resin, breaking through the limitation of traditional modified glass fibers that only improve interfacial compatibility; it adopts a synergistic layout of nano / micro dual-scale antimony white and bromine source, forming micro-flame retardant units at the glass fiber interface and constructing a macro-flame retardant network in the matrix, which greatly improves the flame retardant efficiency; the introduction of compound laser engraving additives (carbon black / zinc oxide) solves the problem of insufficient laser marking contrast often faced by high flame retardant materials through the synergistic optical effect of carbonization and foaming.

[0038] 2. From a process perspective, the stepwise mixing strategy solves the problems of pre-dispersion of components with significantly different densities (brominated polystyrene and antimony white), uniform distribution of various small-dose additives in the resin, and morphological protection of functional glass fibers; the mild and efficient glass fiber surface modification process ensures the selectivity and integrity of the chemical grafting reaction; and the segmented control of extrusion temperature and speed ensures the melt mixing effect while avoiding resin degradation and flame retardant failure caused by high temperature. Detailed Implementation

[0039] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0040] In the examples and comparative examples, the lubricant was stearic acid, the hydrolysis inhibitor was a carbodiimide compound (Stabaxol P series), the UV absorber was a benzotriazole, and the titanate coupling agent was isopropyltris(dioctylpyrophosphate) titanate.

[0041] Example 1

[0042] A method for preparing laser-marked PET material, by weight, includes the following steps:

[0043] (1) Preparation of special glass fiber:

[0044] (1-1) Select 6mm long E glass fiber chopped strands as the substrate;

[0045] (1-2) The substrate was impregnated in an ethanol-water solution containing 2% by mass of vinyltris(β-methoxyethoxy)silane and 3% by mass of brominated epoxy resin E-44 in a volume ratio of 9:1. The reaction was carried out at 70°C for 3 hours. After drying, the glass fiber with flame-retardant and compatibilizing groups was obtained.

[0046] (1-3) The flame-retardant and compatibilizing group glass fiber, 1% of the mass of modified glass fiber nano antimony white and 3% of the mass of 35nm nano antimony white titanate coupling agent are mixed in a high-speed mixer at 1000rpm for 4 minutes to obtain special glass fiber.

[0047] (2) Preparation of laser-marked PET material:

[0048] (2-1) Weigh out the following components by weight: 100 parts PET resin, 20 parts special glass fiber, 2.5 parts carbon black and zinc oxide in a mass ratio of 1:0.75, 2.5 parts brominated polystyrene powder, 1.5 parts micron antimony white, 1.5 parts nano silica, 1 part antioxidant 1010 and antioxidant 168 compounded in a mass ratio of 1:1.5, 1.5 parts aluminum hydroxide and zinc borate compounded in a mass ratio of 2:1.25, and 2.5 parts auxiliary reagent; the auxiliary reagent is a lubricant.

[0049] (2-2) Brominated polystyrene powder and 12μm micron antimony white were mixed at 500rpm for 15 minutes to obtain a synergistic flame retardant premix.

[0050] (2-3) Add PET resin, synergistic flame retardant premix, nucleating agent, antioxidant, glow wire additive, and auxiliary reagents to a high-speed mixer. Mix for 12 minutes at 700 rpm for the second time until homogeneous. Then add special glass fiber and mix for 6 minutes at 500 rpm for the third time until homogeneous. Add the mixture to a twin-screw extruder. Control the screw temperature in segments at 235℃, 245℃, 255℃, 265℃, and 275℃. Extrude and granulate the material at a screw speed of 175 rpm to obtain laser-marked PET material.

[0051] Example 2

[0052] A method for preparing laser-marked PET material, by weight, includes the following steps:

[0053] (1) Preparation of special glass fiber:

[0054] (1-1) Select 3mm long E glass fiber chopped strands as the substrate;

[0055] (1-2) The substrate was impregnated in an ethanol-water solution containing 1% by mass of vinyltris(β-methoxyethoxy)silane and 2% by mass of brominated epoxy resin E-44 in a volume ratio of 9.5:1. The reaction was carried out at 60°C for 4 hours. After drying, glass fiber with flame-retardant and compatibilizing groups was obtained.

[0056] (1-3) The flame-retardant and compatibilizing group glass fiber, 0.5% of the modified glass fiber mass of nano antimony white and 2% of the mass of 20nm nano antimony white titanate coupling agent are mixed in a high-speed mixer at 800rpm for 5 minutes to obtain special glass fiber.

[0057] (2) Preparation of laser-marked PET material:

[0058] (2-1) Weigh out the following by mass: 80 parts PET resin, 10 parts special glass fiber, 0.5 parts carbon black and zinc oxide in a mass ratio of 1:0.5, 0.5 parts brominated polystyrene powder, 0.1 parts micron antimony white, 0.1 parts nano silica, 0.1 parts antioxidant 1010 and antioxidant 168 compounded in a mass ratio of 1:1, 0.1 parts aluminum hydroxide and zinc borate compounded in a mass ratio of 2:1, and 0 parts auxiliary reagents;

[0059] (2-2) Brominated polystyrene powder and 5μm micron antimony white were mixed at 400rpm for 20 minutes to obtain a synergistic flame retardant premix.

[0060] (2-3) Add PET resin, synergistic flame retardant premix, nucleating agent, antioxidant, glow wire additive, and auxiliary reagents to a high-speed mixer. Mix for 15 minutes at 600 rpm for the second time until homogeneous. Then add special glass fiber and mix for 8 minutes at 400 rpm for the third time until homogeneous. Add the mixture to a twin-screw extruder. Control the screw temperature in segments at 230℃, 240℃, 250℃, 260℃, and 270℃. Extrude and granulate the material at a screw speed of 150 rpm to obtain laser-marked PET material.

[0061] Example 3

[0062] A method for preparing laser-marked PET material, by weight, includes the following steps:

[0063] (1) Preparation of special glass fiber:

[0064] (1-1) Select 10mm long E glass fiber chopped strands as the substrate;

[0065] (1-2) The substrate was impregnated in an ethanol-water solution containing 3% by mass of vinyltris(β-methoxyethoxy)silane and 5% by mass of brominated epoxy resin E-44 in a volume ratio of 9:1. The reaction was carried out at 80°C for 2 hours. After drying, the glass fiber with flame-retardant and compatibilizing groups was obtained.

[0066] (1-3) The flame-retardant and compatibilizing group glass fiber, 2% of the mass of the modified glass fiber nano antimony white and 5% of the mass of the 50nm nano antimony white titanate coupling agent are mixed in a high-speed mixer at 1200rpm for 3 minutes to obtain the special glass fiber.

[0067] (2) Preparation of laser-marked PET material:

[0068] (2-1) Weigh the following by mass: 120 parts PET resin, 30 parts special glass fiber, 5 parts carbon black and zinc oxide in a 1:1 mass ratio, 5 parts brominated polystyrene powder, 3 parts micron antimony white, 3 parts nano silica, 2 parts antioxidant 1010 and antioxidant 168 compounded in a 1:2 mass ratio, 3 parts aluminum hydroxide and zinc borate compounded in a 2:1.5 mass ratio, and 5 parts auxiliary reagent; the auxiliary reagent is a lubricant.

[0069] (2-2) Brominated polystyrene powder and 20μm micron antimony white were mixed at 600rpm for 10 minutes to obtain a synergistic flame retardant premix.

[0070] (2-3) Add PET resin, synergistic flame retardant premix, nucleating agent, antioxidant, glow wire additive, and auxiliary reagents to a high-speed mixer. Mix at 800 rpm for 10 minutes for the second time until homogeneous. Then add special glass fiber and mix at 600 rpm for 5 minutes for the third time until homogeneous. Then add to a twin-screw extruder. Control the screw temperature in segments at 240℃, 250℃, 260℃, 270℃, and 280℃. Extrude and granulate at a screw speed of 200 rpm to obtain laser-marked PET material.

[0071] Example 4

[0072] A method for preparing laser-marked PET material, by weight, includes the following steps:

[0073] (1) Preparation of special glass fiber:

[0074] (1-1) Select 5mm long E glass fiber chopped strands as the substrate;

[0075] (1-2) The substrate was impregnated in an ethanol-water solution containing 1.5% by mass of vinyltris(β-methoxyethoxy)silane and 4% by mass of brominated epoxy resin E-44 in a volume ratio of ethanol and water of 9.2:1. The reaction was carried out at 65°C for 3.5 hours. After drying, glass fiber with flame-retardant and compatibilizing groups was obtained.

[0076] (1-3) The flame-retardant and compatibilizing group glass fiber, 0.8% of the modified glass fiber mass of nano antimony white and 4% of the 25nm nano antimony white mass of titanate coupling agent are mixed in a high-speed mixer at 900 rpm for 4.5 minutes to obtain special glass fiber;

[0077] (2) Preparation of laser-marked PET material:

[0078] (2-1) Weigh the following by mass: 90 parts PET resin, 15 parts special glass fiber, 3 parts carbon black and zinc oxide in a mass ratio of 1:0.6, 1 part brominated polystyrene powder, 0.5 parts micron antimony white, 2 parts nano silica, 0.5 parts antioxidant 1010 and antioxidant 168 compounded in a mass ratio of 1:1.2, 2 parts aluminum hydroxide and zinc borate compounded in a mass ratio of 2:1.1, and 1 part auxiliary reagent; the auxiliary reagent is an anti-hydrolysis agent.

[0079] (2-2) Brominated polystyrene powder and 8μm micron antimony white were mixed at 450 rpm for 18 minutes to obtain a synergistic flame retardant premix.

[0080] (2-3) Add PET resin, synergistic flame retardant premix, nucleating agent, antioxidant, glow wire additive, and auxiliary reagents to a high-speed mixer. Mix for 14 minutes at 650 rpm for the second time until homogeneous. Then add special glass fiber and mix for 7 minutes at 450 rpm for the third time until homogeneous. Then add to a twin-screw extruder. Control the screw temperature in segments at 232℃, 242℃, 252℃, 262℃, and 272℃. Extrude and granulate at a screw speed of 160 rpm to obtain laser-marked PET material.

[0081] Example 5

[0082] A method for preparing laser-marked PET material, by weight, includes the following steps:

[0083] (1) Preparation of special glass fiber:

[0084] (1-1) Select 8mm long E glass fiber chopped strands as the substrate;

[0085] (1-2) The substrate was impregnated in an ethanol-water solution containing 2.5% by mass of vinyltris(β-methoxyethoxy)silane and 3% by mass of brominated epoxy resin E-44 in a volume ratio of ethanol and water of 9.4:1. The reaction was carried out at 75°C for 2.5 hours. After drying, glass fiber with flame-retardant and compatibilizing groups was obtained.

[0086] (1-3) The flame-retardant and compatibilizing group glass fiber, 1.5% of the modified glass fiber mass of nano antimony white and 2.5% of the 45nm nano antimony white mass of titanate coupling agent are mixed in a high-speed mixer at 1100 rpm for 3.5 minutes to obtain special glass fiber;

[0087] (2) Preparation of laser-marked PET material:

[0088] (2-1) Weigh the following by mass: 110 parts PET resin, 25 parts special glass fiber, 4 parts carbon black and zinc oxide in a mass ratio of 1:0.9, 4 parts brominated polystyrene powder, 2 parts micron antimony white, 1 part nano silica, 1.5 parts antioxidant 1010 and antioxidant 168 compounded in a mass ratio of 1:1.8, 0.5 parts aluminum hydroxide and zinc borate compounded in a mass ratio of 2:1.4, and 4 parts auxiliary reagents; the auxiliary reagents are ultraviolet absorbers.

[0089] (2-2) Brominated polystyrene powder and 15μm micron antimony white were mixed at 550rpm for 12 minutes to obtain a synergistic flame retardant premix.

[0090] (2-3) Add PET resin, synergistic flame retardant premix, nucleating agent, antioxidant, glow wire additive, and auxiliary reagents to a high-speed mixer. Mix for 11 minutes at 750 rpm for the second time until homogeneous. Then add special glass fiber and mix for 5.5 minutes at 550 rpm for the third time until homogeneous. Then add to a twin-screw extruder. Control the screw temperature in segments at 238℃, 248℃, 258℃, 268℃, and 278℃. Extrude and granulate at a screw speed of 190 rpm to obtain laser-marked PET material.

[0091] Comparative Example 1

[0092] The only difference from Example 1 is that the glass fiber was not modified.

[0093] Comparative Example 2

[0094] The only difference from Example 1 is that (1-2) the substrate is impregnated in an ethanol-water solution containing 2% by mass of vinyltris(β-methoxyethoxy)silane in a volume ratio of 9:1, reacted at 70°C for 3 hours, and dried to obtain glass fiber with compatibilizing groups.

[0095] Comparative Example 3

[0096] The only difference from Example 1 is that (1-2) the substrate is impregnated in an ethanol-water solution containing 3% by mass of brominated epoxy resin E-44 in a volume ratio of 9:1, reacted at 70°C for 3 hours, and dried to obtain glass fiber with flame-retardant groups.

[0097] Comparative Example 4

[0098] The only difference from Example 1 is that in steps (1-3), the high-speed uniform mixing process is: mixing at 750 rpm for 4 minutes in a high-speed mixer.

[0099] Comparative Example 5

[0100] The only difference from Example 1 is that in steps (1-3), the high-speed uniform mixing process is: mixing at 1250 rpm for 4 minutes in a high-speed mixer.

[0101] Comparative Example 6

[0102] The only difference from Example 1 is that steps (1-3) were not performed, and the glass fiber with flame-retardant-compensating groups was added in step (2-3).

[0103] Comparative Example 7

[0104] The only difference from Example 1 is that no titanate coupling agent was added in (1-3).

[0105] Comparative Example 8

[0106] The only difference from Example 1 is that step (2-2) is omitted.

[0107] Comparative Example 9

[0108] The only difference from Example 1 is that in step (2-1), all weighed materials are directly mixed at 600 rpm for 33 min.

[0109] Comparative Example 10

[0110] The only difference from Example 1 is that the third mixing was carried out at 700 rpm for 6 minutes to ensure uniformity.

[0111] Comparative Example 11

[0112] The only difference from Example 1 is that (2-1) the following components are weighed by mass: 75 parts PET resin, 8 parts special glass fiber, 2.5 parts carbon black and zinc oxide in a mass ratio of 1:0.75, 2.5 parts brominated polystyrene powder, 1.5 parts micron antimony white, 1.5 parts nano silica, 1 part antioxidant 1010 and antioxidant 168 compounded in a mass ratio of 1:1.5, 1.5 parts aluminum hydroxide and zinc borate compounded in a mass ratio of 2:1.25, and 2.5 parts auxiliary reagent; the auxiliary reagent is a lubricant.

[0113] Comparative Example 12

[0114] The only difference from Example 1 is that (2-1) the following components are weighed by mass: 135 parts PET resin, 35 parts special glass fiber, 2.5 parts carbon black and zinc oxide in a mass ratio of 1:0.75, 2.5 parts brominated polystyrene powder, 1.5 parts micron antimony white, 1.5 parts nano silica, 1 part antioxidant 1010 and antioxidant 168 compounded in a mass ratio of 1:1.5, 1.5 parts aluminum hydroxide and zinc borate compounded in a mass ratio of 2:1.25, and 2.5 parts auxiliary reagent; the auxiliary reagent is a lubricant.

[0115] Detection method:

[0116] 1. Laser Marking Performance: A 1064nm fiber laser marking machine (power 20W, scanning speed 300mm / s, frequency 50kHz) was used to mark a 20mm × 20mm QR code and a 1mm high serial number on the sample surface. An industrial-grade QR code scanner was used to scan the sample 100 times consecutively, and the success rate was calculated. A colorimeter was used to measure the contrast (L value difference) between the marked and unmarked areas. For abrasion resistance, referring to standard GB / T 5478-2008 "Plastics Rolling Abrasion Test Method", the sample was rubbed 100 times using a dedicated friction testing machine (load 500g, friction head diameter 16mm), and the scanning success rate and contrast were evaluated again. For heat resistance, referring to standard GB / T 7141-2008 "Plastics Thermal Aging Test Method", the marked sample was placed in a 120℃ forced-air drying oven for 1000 hours, and its appearance, scanning success rate, and contrast were evaluated.

[0117] 2. Vertical flammability rating: Tested according to GB / T 2408-2021 "Determination of flammability of plastics - Horizontal and Vertical Methods", with a sample thickness of 3.2 mm.

[0118] 3. Glow Wire Flammability Index (GWFI): The test shall be conducted in accordance with GB / T 5169.12-2024 "Fire Hazard Testing of Electrical and Electronic Products - Part 12: Basic Test Methods for Glow Wire / Hot Wire Materials - Test Method for Glow Wire Flammability Index (GWFI)".

[0119] 4. Mechanical properties:

[0120] Tensile properties: Tested according to GB / T 1040.2-2006 "Determination of tensile properties of plastics - Part 2: Test conditions for molded and extruded plastics", with a tensile speed of 5 mm / min; Flexural properties: Tested according to GB / T 9341-2008 "Determination of flexural properties of plastics", with a span-to-thickness ratio of 16:1 and a speed of 2 mm / min; Notched impact strength: Samples were prepared and tested according to GB / T 1043.1-2008 "Determination of impact properties of simply supported beams of plastics - Part 1: Non-instrumental impact test", with a notch type of A.

[0121] The laser marking inspection results are shown in Table 1:

[0122] Table 1. Laser marking test results of the examples and comparative examples

[0123]

[0124] Combustion characteristics and mechanical properties are shown in Table 2.

[0125] Table 2. Test results of combustion characteristics and mechanical properties of the examples and comparative examples.

[0126]

[0127] In the background, pure PET resin has low absorption efficiency for infrared lasers, making it difficult to form high-contrast markings. While adding laser-sensitive additives can improve the marking effect, it can easily lead to the deterioration of mechanical properties. Introducing high-efficiency flame retardants can reflect or scatter laser energy, interfering with marking. When reinforced with glass fiber, the poor compatibility with the matrix and additive interface can cause problems such as material embrittlement and rough marking surfaces. Existing technologies have failed to effectively solve the synergistic problems between these properties and cannot simultaneously meet the needs of multi-dimensional use. The embodiment achieves a performance breakthrough through innovative modification of specialized glass fiber. This is achieved by chemically grafting silane and brominated epoxy resin onto the glass fiber surface, simultaneously integrating compatibilization and brominated flame retardant functions. Combined with the synergistic dispersion of nano-antimony white and titanate coupling agent, microscopic flame-retardant units are constructed at the glass fiber interface. Simultaneously, nano / micro-scale antimony white and the bromine source in the matrix form a macroscopic flame-retardant network, significantly improving flame-retardant efficiency. The synergistic effect of photothermal conversion carbonization of carbon black and thermal decomposition foaming of zinc oxide in the compounded laser engraving additive solves the problem of insufficient contrast in laser marking of high flame-retardant materials. The stepwise mixing process, involving premixing the flame-retardant components, then mixing the additives and resin, and finally mixing into the glass fiber at low speed, ensures uniform dispersion of all components while avoiding glass fiber breakage and wear of the surface modification layer. This results in the material exhibiting stable laser marking performance after weathering and wear resistance, high flame retardancy (V-0 rating for vertical burning), and excellent mechanical properties. Furthermore, when the glass fiber length, modifier concentration, and process parameters are within the optimal range, the performance shows an even better trend.

[0128] Compared to Example 1, Comparative Example 1, due to the lack of glass fiber modification, had poor interfacial compatibility with the PET matrix, resulting in decreased mechanical properties, discontinuous flame-retardant network, and reduced laser marking contrast. Comparative Example 2 used only silane-modified glass fiber, lacking bromine-based flame-retardant groups, leading to a lower glow wire flammability index and a flame-retardant rating of only V-1. Comparative Example 3 used only brominated epoxy resin-modified glass fiber, lacking the compatibilizing effect of silane, resulting in interface defects and weak mechanical properties. Comparative Example 4 had an excessively low glass fiber mixing speed, resulting in uneven dispersion of nano-antimony white and decreased laser marking and flame-retardant performance. Comparative Example 5 had an excessively high glass fiber mixing speed, causing glass fiber breakage, wear of the surface modification layer, weakened glass fiber reinforcement, and impaired flame-retardant function. Comparative Example 6 did not add nano-antimony white or coupling agent, resulting in poor interfacial properties at the glass fiber interface. The lack of microscopic flame-retardant units resulted in an incomplete flame-retardant network. Comparative Example 7, lacking a titanate coupling agent, caused nano-antimony white to easily agglomerate, leading to poor dispersibility and reduced performance. Comparative Example 8, without flame-retardant premixing, resulted in uneven dispersion of brominated polystyrene and micronized antimony white, lowering the flame-retardant rating to V-2 and causing a decline in other properties. Comparative Example 9, by directly mixing all materials, resulted in uneven dispersion of additives and potential damage to glass fibers, leading to a comprehensive decline in all properties. Comparative Example 10, with excessively high mixing speed in the third mixing stage, damaged the morphology and functional layers of the glass fibers, deteriorating mechanical and marking properties. Comparative Example 11, due to insufficient PET and glass fiber content, lacked adequate substrate support and reinforcement, significantly reducing mechanical properties. Comparative Example 12, due to excessive PET and glass fiber content, resulted in excessive glass fiber dispersion, leading to damage to laser marking and mechanical properties.

Claims

1. A method for preparing laser-marked PET material, characterized in that, By weight, the following steps are included: (1) Preparation of special glass fiber: (1-1) Select E glass fiber chopped strands with a length of 3-10 mm as the substrate; (1-2) The substrate is impregnated in an ethanol aqueous solution containing 1-3% by mass of vinyltris(β-methoxyethoxy)silane and 2-5% by mass of brominated epoxy resin E-44, and reacted at 60-80°C for 2-4 hours. After drying, the flame-retardant-compatibilizing group glass fiber is obtained. (1-3) Mix the flame-retardant and compatibilizing glass fiber, 0.5-2% of the mass of the modified glass fiber, and 2-5% of the mass of the nano-antimony white and titanate coupling agent in a high-speed mixer at 800-1200 rpm for 3-5 minutes to obtain special glass fiber. (2) Preparation of laser-marked PET material: (2-1) Weigh out the following components by weight: 100-110 parts PET resin, 20-25 parts special glass fiber, 0.5-5 parts compound laser engraving agent, 0.5-5 parts brominated polystyrene powder, 0.1-3 parts micron antimony white, 0.1-3 parts nucleating agent, 0.1-2 parts antioxidant, 0.1-3 parts glow wire agent, and 0-5 parts auxiliary reagents; The compound laser engraving agent is carbon black and zinc oxide in a mass ratio of 1:0.5-1; the nucleating agent is nano-silica; the glow wire agent is aluminum hydroxide and zinc borate compounded in a mass ratio of 2:1-1.

5. (2-2) The brominated polystyrene powder and micron-sized antimony white were stirred evenly for the first time to obtain a synergistic flame retardant premix; (2-3) Add PET resin, synergistic flame retardant premix, compound laser engraving agent, nucleating agent, antioxidant, glow wire agent, and auxiliary reagent to a high-speed mixer. After the second mixing is uniform, add special glass fiber. After the third mixing is uniform, add to a twin-screw extruder and extrude and granulate to obtain laser marking PET material. The second mixing process involves mixing at 600-800 rpm for 10-15 minutes; the third mixing process involves mixing at 400-600 rpm for 5-8 minutes.

2. The method for preparing laser-marked PET material according to claim 1, characterized in that, In steps (1-2), the volume ratio of ethanol to water in the ethanol-water solution is 9-9.5:

1.

3. The method for preparing laser-marked PET material according to claim 1, characterized in that, In step (2-1), the antioxidant is antioxidant 1010 and antioxidant 168 compounded in a mass ratio of 1:1-2; the auxiliary reagent is one or more of lubricant, anti-hydrolysis agent or ultraviolet absorber.

4. The method for preparing laser-marked PET material according to claim 1, characterized in that, During the extrusion granulation process, the screw temperature is controlled in segments at 230-240℃, 240-250℃, 250-260℃, 260-270℃, and 270-280℃, and the screw speed is 150-200 rpm.

5. The method for preparing laser-marked PET material according to claim 1, characterized in that, The process of first stirring evenly in step (2-2) is to mix at 400-600 rpm for 10-20 minutes.

6. The method for preparing laser-marked PET material according to claim 1, characterized in that, The particle size of the nano-antimony white in step (1-3) is 20-50 nm; the particle size of the micron-antimony white in step (2-1) is 5-20 μm.

7. A laser-marked PET material, characterized in that, The laser-marked PET material is prepared according to any one of claims 1-6.

8. A laser-marked PET material according to claim 7 is applied to electrical structural components, communication equipment structural components, and medical equipment structural components.

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