A laser-engraving master batch for high-transmittance polypropylene material and a preparation method thereof

Abstract

The present application relates to the technical field of polypropylene composite material, and particularly discloses a laser-engravable master batch for high-transmittance polypropylene material and a preparation method thereof.The material is composed of the following raw materials in parts by weight: titanium dioxide 5-25 wt%; rare earth oxide 1-5 wt%; amorphous alpha-olefin copolymer 0.5-4 wt%; other additives 0.1-2 wt%; and the rest polypropylene.Based on the problem that the high-transmittance polypropylene material is not easy to be laser-engraved, the present application uses special titanium dioxide and rare earth oxide to continuously absorb the heat generated during the laser-engraving process, so as to endow the high-transmittance polypropylene material with laser-engravability and various laser-engraving effects, and also ensure that the high-transmittance polypropylene material has good light-transmittance effect.

Description

Technical Field

[0001] This invention relates to the field of polymer materials technology, and in particular to a laser-engraved masterbatch suitable for use in high-transparency polypropylene materials. Background Technology

[0002] Polypropylene (PP) is widely used in automobiles, home appliances, medical devices, and daily necessities due to its simple polymerization process, non-toxicity, odorlessness, tastelessness, strong chemical stability, resistance to acids and alkalis, low density, light weight, and good thermoplastic processing properties. It is particularly prevalent in automotive parts such as bumpers, dashboards, door panels, pillars, and wheel arches. With the development of new energy vehicles in recent years, many bold, avant-garde, and disruptive design elements have been introduced, leading to increasing demands for intelligence and technological sophistication. Compared to traditional parts, adding optical elements to interior and exterior trims not only provides basic lighting and decoration but also enhances brand image, driver assistance, and safety awareness. Furthermore, it can add new functions such as interactive lighting and human-vehicle interaction, thereby increasing product competitiveness. Therefore, some automotive parts require a certain degree of light transmittance.

[0003] Currently, translucent automotive interior and exterior components are mainly made by spraying paint onto PP substrates to achieve a good appearance. Simultaneously, laser engraving is used to create a unique light-emitting effect, providing consumers with a strong visual experience. Laser engraving refers to the process of using a laser beam to cause chemical and physical changes in the surface material, thus etching the desired marks, or using light energy to ablate parts of the material to reveal the desired graphics or text. It is a surface treatment process, similar to screen printing and pad printing, which can achieve text or pattern effects on products. However, laser engraving has advantages such as fast marking speed, beautiful patterns, high resolution, and high precision.

[0004] Using laser engraving technology for large-area color separation on automotive parts is a novel application model. However, the paint spraying process is complex, causes significant environmental pollution, and is technically challenging, leading to its increasing replacement by paint-free systems. Adding laser engraving additive masterbatch can achieve various color separation effects, such as black engraving on white, white engraving on black, and white engraving on blue. Currently, laser engraving additives added to translucent PP systems severely impact the light transmittance of both the material and the parts. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention provides a laser-engraved masterbatch suitable for high-transparency polypropylene materials and its preparation method.

[0006] The objective of this invention is achieved through the following technical solution:

[0007] The present invention provides a laser-engraved masterbatch suitable for use in high-transparency polypropylene materials, comprising the following raw materials in parts by weight:

[0008] Titanium dioxide: 5-25 wt%;

[0009] Rare earth oxides 1-5 wt%;

[0010] Amorphous α-olefin copolymers, 0.5–4 wt%;

[0011] Additives: 0.1–2 wt%;

[0012] Polypropylene: The remaining components.

[0013] The titanium dioxide mentioned is rutile nano-titanium dioxide with a grain size of 1–50 nm.

[0014] The rare earth oxide is one of lanthanum oxide, cerium oxide, praseodymium oxide, etc., with a particle size of ≤300 μm.

[0015] The amorphous α-olefin copolymer has a melt viscosity ≤9000 mPa·s at 190°C.

[0016] The additives are mainly a combination of antioxidants and light stabilizers. The antioxidants are mainly a combination of three of the following: hindered phenols, phosphites, and thiosulfates. The light stabilizers are a combination of hindered amines and ultraviolet absorbers.

[0017] The polypropylene resin is a random polypropylene resin, with a melt flow rate of 2-30 g / 10 min under the test conditions of 230℃@2.16 kg, visible light transmittance (3.2 mm) ≥65%, and haze (3.2 mm) ≥20%.

[0018] The above-mentioned method for preparing laser-engraved masterbatch suitable for high-transparency polypropylene materials comprises the following production steps:

[0019] (1) Dissolve titanium dioxide in a strong acid-weak base salt at a mass ratio of 1:10 to 1:40, sonicate for 0.5 to 1 hour, add the corresponding proportion of rare earth oxides, and sonicate again for 1 to 2 hours.

[0020] (2) After ultrasonic treatment, add the product to a high-speed centrifuge for centrifugal drying. After centrifugation, add deionized water for multiple washes, each wash lasting about 10 to 30 minutes. Generally, wash 2 to 3 times to ensure that the pH value of the deionized water is close to 7. After washing, vacuum dry the product.

[0021] (3) The dried powder, polypropylene, amorphous α-olefin copolymer, and additives are added to a high-speed mixer according to the corresponding weight ratio and mixed evenly. Then, the mixture is added to the main feed port of a twin-screw extruder for melt mixing. The extrusion temperature is 200-230℃ and the screw speed is 200-600rpm. After melt extrusion, cooling, granulation, and homogenization, a laser-engraved masterbatch suitable for high-transparency polypropylene materials is obtained.

[0022] This invention utilizes ultrafine nano-sized titanium dioxide, which can significantly absorb laser energy without affecting the light transmittance of the transparent PP material. Rare earth oxides also have strong laser absorption capabilities, and using different rare earth oxides can alter the hue after laser engraving, achieving an effect similar to spray painting laser engraving, thus optimizing the production process and reducing environmental pollution and costs.

[0023] Amorphous α-olefin copolymers have good lubrication and processing properties. Compared with traditional stearates, these copolymers have a larger molecular weight and are less prone to stickiness. At the same time, these copolymers have excellent light transmittance, PP compatibility and lubrication, and will not affect the light transmittance of transparent PP materials, making them suitable for high-transmittance PP systems. Detailed Implementation

[0024] The present invention can be further described through the following preferred embodiments, but these embodiments are only illustrative and do not define the scope of the present invention.

[0025] In the composite material formulations of the examples and comparative examples, the polypropylene resin in the laser-engraved masterbatch used for the high-transmittance polypropylene material was provided by Shandong Jingbo Polyolefin New Material Co., Ltd., with the trade name RP340R, and a melt flow rate of 28 g / 10 min at 2.16 kg @ 230 °C. Titanium dioxide was provided by Ansteel Group Vanadium Titanium (Iron) Research Institute, with the trade name PGNA-10 and a grain size of approximately 9 nm. Rare earth oxides were provided by Ganzhou Qiming New Material Co., Ltd., specifically lanthanum oxide, with a particle size of approximately 40 nm. The amorphous α-olefin copolymer was provided by Evonik Degussa (China) Co., Ltd., with the trade name VESTOPLAST 708. Antioxidants were provided by Tianjin Lianlong New Material Co., Ltd., with the trade names Irganox 3114, Irganox 168, and Negonox DSTP, in a ratio of 2:1:1; the light stabilizer was provided by Xinxiu Chemical, with the trade name 5229; the addition ratio of antioxidant to light stabilizer was 2:1. In the comparative example, the commercially available laser engraving additive masterbatch was supplied by Guangdong Dazhan Jiyuan New Material Technology Co., Ltd. In the control sample, the conventional titanium dioxide was supplied by CNNC Titanium Dioxide Co., Ltd. as R-2219, with a particle size of 0.3 μm.

[0026] Examples A1-A7 and Comparative Examples B1-B3 describe the preparation of high-transmittance PP laser engraving masterbatch.

[0027] According to the proportions in Table 1, titanium dioxide was dissolved in ammonium sulfate solution at a mass ratio of 1:20, and sonicated for 0.5 to 1 hour. Then, rare earth oxides of the appropriate proportion were added, and the mixture was sonicated again for 1 to 2 hours.

[0028] After ultrasonication, the product is centrifuged and dried in a high-speed centrifuge. After centrifugation, deionized water is added for multiple washes, each lasting about 10 to 30 minutes. Generally, the product is washed 2 to 3 times to ensure that the pH value of the deionized water is close to 7. After washing, the product is vacuum dried.

[0029] The dried powder, polypropylene, amorphous α-olefin copolymer, and additives are added according to the corresponding weight ratios and then mixed evenly in a high-speed mixer. The mixture is then fed into the main feed inlet of a twin-screw extruder for melt mixing. The extrusion temperature is 200–230℃, and the screw speed is 200N / 600rpm. After melt extrusion, cooling, granulation, and homogenization, a laser-engraved masterbatch suitable for high-transparency polypropylene materials is obtained.

[0030] Table 1. Distribution ratios (parts by weight) of each group in Examples A1-A7 and Comparative Examples B1-B3

[0031]

[0032] According to the proportions in Table 2, polypropylene and the laser engraving masterbatch shown in Table 1 were melt-mixed in a twin-screw extruder with an aspect ratio of 40-52:1, and then extruded and granulated at an extrusion temperature between 160-230℃. The resulting material was used for injection molding of 3mm samples. After injection molding, the samples were placed on a laser engraving machine for laser engraving. The light transmittance of the non-laser-engraved areas was tested, with specific transmittance testing according to GB / T2410 standard. In addition, the color effect after laser engraving was mainly determined by testing the L value of the laser-engraved area using a CM-2500C spectrophotometer. The relevant results are shown in Table 3.

[0033] Table 2: Component formulations of Examples 1-7 and Comparative Examples 1-5.

[0034]

[0035] Table 3: Comparison of optical performance and laser engraving effect between Examples 1-7 and Comparative Examples 1-5

[0036]

[0037] The results of transmittance and laser engraving color development in Examples 1, 1-2, and 4-5 show that the laser engraving masterbatch prepared using titanium dioxide and rare earth metal oxides with special particle size and specifications does not significantly reduce the transmittance of PP materials and imparts good laser engraving properties to the translucent PP materials. Conventional carbon dioxide and laser engraving masterbatch have a greater impact on the transmittance of PP materials. The results of transmittance and laser engraving color development in Examples 1-3 show that as the titanium dioxide content increases, the transmittance decreases slightly, but the decrease is not significant, and the L value decreases significantly after laser engraving. A lower L value indicates higher blackness, which means a more obvious color difference effect after laser engraving and a better appearance in actual use. The results of transmittance and laser engraving color development in Examples 2, 4, and 5 show that the transmittance decreases slightly with increasing rare earth content, but the color development effect after laser engraving is good. The transmittance and laser engraving color development results of Examples 4, 6, and 7 show that the addition of amorphous α-olefin copolymer can improve the dispersion of titanium dioxide nanoparticles and rare earth oxides, thereby reducing the impact on the transmittance of PP material. At the same time, the copolymer has no effect on the laser engraving effect. Therefore, the addition of amorphous α-olefin copolymer helps to prepare laser engraving masterbatch for this high-transmittance PP material.

[0038] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope defined in the claims.

Claims

1. A laser engraving master granule suitable for high light transmission polypropylene material, characterized in that, The following weight parts of raw materials are used: Titanium dioxide: 5-25wt%; Rare earth oxide: 1-5wt%; Amorphous α-olefin copolymer: 0.5-4wt%; Auxiliary agent: 0.1-2wt%; Polypropylene: the rest; The titanium dioxide is rutile type nanometer titanium dioxide, with a grain size of 1-100nm.

2. The laser engraving master granule for high-transparency polypropylene material according to claim 1, characterized in that: The rare earth oxide is one of lanthanum oxide, cerium oxide and praseodymium oxide, with a particle size of ≤500nm.

3. The laser engraving master granule for high-transparency polypropylene material according to claim 1, characterized in that: The amorphous α-olefin copolymer has a melt viscosity of ≤10000mPa·s at 190℃.

4. The laser engraving master granule for high-transparency polypropylene material according to claim 1, characterized in that: The auxiliary agent is a combination of an antioxidant and a light stabilizer, wherein the antioxidant is a combination of several of hindered phenol, phosphite and thiosulfate; the light stabilizer is one and several of hindered amine and ultraviolet absorber.

5. The laser engraving master granule for high-transparency polypropylene material according to claim 1, characterized in that: The polypropylene is random polypropylene resin, with a melt flow rate of 0.5-30g / 10min at 230℃ under a test condition of 2.16kg, a visible light transmittance of ≥60% and a haze of ≥10%.

6. The process for the preparation of laser engraving master granules suitable for high transparent polypropylene materials according to any one of claims 1 to 5, characterized in that, The production steps are as follows: (1) Dissolve the titanium dioxide in a strong acid and weak base salt at a mass ratio of 1:10-1:40, and then add the rare earth oxide in a corresponding proportion after ultrasonic treatment for 0.5-1h and ultrasonic treatment for 1-2h again; (2) After the ultrasonic treatment, centrifugal dry in a high-speed centrifuge, and then wash with deionized water for 2-3 times, each time for 10-30min, to ensure that the pH value of the deionized water is close to 7, and then vacuum dry after the washing; (3) Add the dried powder, polypropylene, amorphous α-olefin copolymer and auxiliary agent in a corresponding weight ratio into a high-speed mixer to mix uniformly, and then add into the main feeding port of a double-screw extruder for melt mixing; the extrusion temperature is 200-230℃, and the screw rotation speed is 200-600rpm; after melt extrusion, cooling, granulation and homogenization, a laser engraving master batch suitable for high-transmittance polypropylene material is obtained.

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