A laser-markable semi-transparent digital display polypropylene composite material, its preparation method and application

Abstract

The present invention discloses a laser-markable semi-transparent digital display polypropylene composite material, its preparation method and application. The laser-markable semi-transparent digital display polypropylene composite material of the present invention comprises the following components by weight: 97-99.7 parts of polypropylene, 0.1-0.3 parts of antioxidant, 0.1-0.5 parts of lubricant, 0.1-1 part of light stabilizer, 0.001-0.1 part of black colorant, 0-0.1 part of white colorant and 0-0.2 part of organic pigment. The polypropylene adopts the ISO 13468-1:2019 standard, and the light transmittance of 2 mm thickness is ≥60%; the light stabilizer is at least one of benzotriazole light stabilizers and / or benzophenone light stabilizers. This polypropylene composite material combines a specific type of light stabilizer with a polypropylene resin having a specific light transmittance, and at the same time acts together with an appropriate amount of black colorant, which can effectively improve the ultraviolet marking effect and digital display effect of the polypropylene composite material.

Description

Technical Field

[0001] The present invention relates to the technical field of compositions of polymer compounds, and more specifically, to a laser-markable semi-transparent digital display polypropylene composite material, a preparation method thereof, and an application thereof. Background Art

[0002] With the continuous upgrading and maturity of home appliance manufacturing technologies, customers have higher and higher requirements for environmental protection and simpler processing technologies; polypropylene resin materials are widely used in large and small home appliance products such as air conditioners, washing machines, rice cookers, electric cooking pots, air fryers, etc., especially in the digital display components of home appliance products. In the prior art, the digital display components usually use transparent materials for the digital display part, and conventional non-transparent materials for the non-digital display part, and then combine inlay or two-color injection molding processes to achieve this. This method has complex processing technology and high production costs. In addition, the overall transparent material is also used for production, and other parts except the digital display part are painted to avoid exposure of the internal structure. This method requires secondary processing and the painting is not environmentally friendly, and at the same time, the scratch resistance is poor.

[0003] A PP alloy with a laser marking function and a preparation method thereof are disclosed in the prior art, which contain the following components in parts by weight: 58-85 parts of polypropylene resin, 5-12 parts of polyethylene resin, 10-30 parts of inorganic filler, 0.5-2 parts of photosensitizer, 0-0.8 parts of light absorber, 0-3.2 parts of color powder, 0.2-0.5 parts of antioxidant, and 0.2-1 part of other additives. Although this composition can achieve the effect of marking dark marks on light-colored parts and light marks on dark-colored parts, its material is opaque and cannot be used as a digital display material; at the same time, it uses infrared marking, and the accuracy and clarity of the marking are quite different from those of ultraviolet marking and cannot meet the requirements of customers for fine processing and the surface of products, and cannot meet the requirements of both laser marking performance and clear digital display effect at the same time. Summary of the Invention

[0004] The object of the present invention is to overcome the defects and deficiencies that the existing laser-markable polypropylene composite material cannot achieve a clear digital display effect when used for digital display components, and to provide a laser-markable semi-transparent digital display polypropylene composite material, which combines a specific type of light stabilizer with a polypropylene resin with a specific light transmittance, and at the same time is matched with a black colorant, so that the polypropylene composite material has excellent marking performance and digital display performance at the same time.

[0005] Another object of the present invention is to provide a preparation method of a laser-markable semi-transparent digital display polypropylene composite material.

[0006] Another object of the present invention is to provide an application of the above-mentioned laser-markable semi-transparent digital display polypropylene composite material in the preparation of digital display components of home appliance products.

[0007] The above objects of the present invention are achieved by the following technical solutions:

[0008] A laser-markable semi-transparent digital display polypropylene composite material, by weight, comprises the following components:

[0009]

[0010] The polypropylene adopts the ISO 13468-1:2019 standard, and the light transmittance of a 2-mm thickness is ≥60%; the light stabilizer is at least one of benzotriazole light stabilizers and / or benzophenone light stabilizers.

[0011] Due to the light transmittance of transparent or semi-transparent materials themselves, during laser marking, part of the laser passes through the material, resulting in insufficient laser energy, causing the material marking to be dark, with poor clarity and a poor marking effect. For the laser-markable semi-transparent digital display polypropylene composite material of the present invention, a specific type of light stabilizer is combined with a polypropylene resin with a specific light transmittance, and an appropriate amount of black colorant is added to enable the polypropylene composite material to achieve a suitable digital display effect. Moreover, the black colorant also has an ultraviolet shielding effect, and when combined with benzotriazole or benzophenone light stabilizers, it can effectively absorb ultraviolet light and prevent the ultraviolet light from destroying the molecular structure of the material and causing material degradation, thus significantly promoting the ultraviolet marking effect of the polypropylene composite material and significantly improving the ultraviolet marking effect.

[0012] The polypropylene adopts the ISO 13468-1:2019 standard, and the light transmittance of a 2-mm thickness can be 65%, 70%, 75%, 80%, 85%, and the present invention is not limited thereto. Preferably, the polypropylene adopts the ISO 13468-1:2019 standard, and the light transmittance of a 2-mm thickness is 84% - 89%. Optionally, the light transmittance of a 2-mm thickness can be 84% - 87%, 87% - 89%, 84%, 87%, and 89%.

[0013] Preferably, the polypropylene adopts the ASTM D-1238 standard, and at a temperature of 190 °C and a load of 2.16 kg, its melt mass flow rate is measured to be 12 - 65 g / 10 min. Specifically, the melt mass flow rate can be 12 - 25 g / 10 min, 28 - 60 g / 10 min.

[0014] Preferably, the black colorant is 0.005 - 0.05 parts by weight.

[0015] In a specific embodiment, the black colorant is carbon black and / or acetylene black; the white colorant is rutile titanium dioxide.

[0016] Specifically, the black colorant has a specific surface area of 60 - 200 m measured in accordance with GB / T 10722-20032 / g, it can be 60 to 100 m 2 / g, 101 to 150 m 2 / g, 151 to 200 m 2 / g; Optionally, the specific surface area of the black colorant is 69 to 150 m 2 / g.

[0017] In a specific embodiment, the specific surface area of the organic pigment of the present invention is 10 to 60 m as measured according to GB / T 10722-2003 2 / g.

[0018] Specifically, the organic pigment can be added according to actual production requirements and can be one or several of phthalocyanine pigments, quinacridone pigments or azo pigments.

[0019] The present invention protects a method for preparing the above-mentioned laser-markable semi-transparent digital display polypropylene composite material, which includes the following steps:

[0020] Add polypropylene, antioxidant, lubricant, light stabilizer, black colorant, white colorant and organic pigment into a twin-screw extruder, mix evenly and then melt and extrude into pellets to obtain the laser-markable semi-transparent digital display polypropylene composite material.

[0021] An application of the above-mentioned laser-markable semi-transparent digital display polypropylene composite material in preparing digital display components of household electrical appliances is also within the protection scope of the present invention.

[0022] Compared with the prior art, the beneficial effects of the present invention are:

[0023] The present invention provides a laser-markable semi-transparent digital display polypropylene composite material, which combines a specific type of light stabilizer with a polypropylene resin having a specific light transmittance, and adds an appropriate amount of black colorant to enable the polypropylene composite material to achieve a suitable digital display effect. Moreover, the black colorant also has an ultraviolet shielding effect. When combined with benzotriazole or benzophenone light stabilizers, it can effectively absorb ultraviolet light and prevent ultraviolet light from destroying the molecular structure of the material and causing material degradation, thereby having an obvious promoting effect on the ultraviolet laser marking effect of the polypropylene composite material and significantly improving the ultraviolet laser marking effect and digital display effect. Specific Embodiments

[0024] The following further illustrates the present invention in conjunction with specific embodiments, but the embodiments do not limit the present invention in any form. Unless otherwise stated, the raw material reagents used in the embodiments of the present invention are conventional raw material reagents purchased.

[0025] 1. Raw Material Reagents

[0026] Polypropylene 1, with a light transmittance of 87% at a thickness of 2 mm, a melt mass flow rate of 12 g / 10 min, grade PPM1200HS, manufacturer: Sinopec;

[0027] Polypropylene 2, with a light transmittance of 84% at a thickness of 2 mm, a melt mass flow rate of 25 g / 10 min, grade RP346R, manufacturer: CNOOC and Shell Petrochemical Company Limited;

[0028] Polypropylene 3, with a light transmittance of 89% at a thickness of 2 mm, a melt mass flow rate of 60 g / 10 min, grade PP M60T, manufacturer: Sinopec;

[0029] Polypropylene 4, with a light transmittance of 61% at a thickness of 2 mm, a melt mass flow rate of 28 g / 10 min, grade BX3800, manufacturer: Sinopec;

[0030] Polypropylene 5, with a light transmittance of 40% at a thickness of 2 mm, a melt mass flow rate of 15 g / 10 min, grade PP YPJ - 1215C, manufacturer: Yangzi Petrochemical Co., Ltd.;

[0031] Light stabilizer 1 is a benzophenone - type light stabilizer, grade RIASORB UV - 531, manufacturer: Tianjin Li'anlong New Materials Co., Ltd.;

[0032] Light stabilizer 2 is a benzotriazole - type light stabilizer, grade CHISORB 5411, manufacturer: Double Bond, Chinese Taiwan;

[0033] Light stabilizer 3 is a high - molecular - weight hindered amine light stabilizer, grade CHIMASSORB 944FDL, manufacturer: BASF;

[0034] Black colorant 1 is carbon black, with a specific surface area of 150 m 2 / g, commercially available;

[0035] Black colorant 2 is acetylene carbon black DENKA BLACK, with a specific surface area of 69 m 2 / g, commercially available;

[0036] White colorant is rutile titanium dioxide, commercially available;

[0037] Phthalocyanine blue, grade Mazcol Blue 153K, manufacturer: Mazda, India;

[0038] Phthalocyanine green, grade MAZCOL GREEN 706K, manufacturer: Mazda, India;

[0039] The antioxidant is obtained by compounding antioxidant Y - 001 (commercially available) and antioxidant Y - 002 (commercially available) in a mass ratio of 1:1;

[0040] The lubricant is erucamide and is commercially available.

[0041] 2. The laser - markable semi - transparent digital display polypropylene composite materials of each example and comparative example of the present invention are prepared by the following preparation method:

[0042] Weigh each component according to the formula, mix them evenly, and then add them into a twin - screw extruder for melt - blending and extrusion granulation, thus obtaining the laser - markable semi - transparent digital display polypropylene composite material.

[0043] Among them, the conditions for melt - extrusion of the twin - screw extruder are: the length - to - diameter ratio of the twin - screw extruder is (25 - 75):1, the temperature is 180°C - 230°C, the screw speed is 75 - 250 r / min, and the feeding speed is 30 - 150 r / min.

[0044] 3. Performance testing

[0045] Make color plates with the size of 83mm * 54mm * 2mm and smooth and flat on both sides from the laser - markable semi - transparent digital display polypropylene composite materials of each example and comparative example of the present invention.

[0046] (1) Transmittance test: Use an X - rite7000A color difference meter to measure the transmittance of the color plate in the thickness direction in the projection mode. The lower the transmittance, the less light passes through, and the worse the display effect.

[0047] (2) Clarity test: Use a Japanese SUGA image clarity meter ICM - 1T to measure the clarity of the color plate at a grating width of 0.125mm. Generally, when the clarity is between 70 - 100, the display effect is clear. The lower the clarity value, the worse the display effect. At the same time, place the color plate on a digital display screen (the digital display screen is disassembled and used from a certain brand of rice cooker on the market) to compare the visual effect of the digital display clarity.

[0048] (3) Use a Dapeng UV - 3X ultraviolet marking machine to mark the color plate. Marking process: marking speed 1800mm / s, frequency: 35 (KHz), Q - pulse width: 27 (microseconds), current: 1A; Use an X - rite7000A color difference meter to measure the L / A / B values of the color plate before and after marking in the SCI mode, and calculate the color difference before and after marking according to the CIE1976 color difference formula.

[0049] Examples 1 - 11

[0050] The weight parts of each component of the laser - markable semi - transparent digital display polypropylene composite material in Examples 1 - 11 are shown in Table 1.

[0051] Table 1 Laser - markable semi - transparent digital display polypropylene composite material in Examples 1 - 11

[0052]

[0053] Comparative Examples 1 - 6

[0054] The weight parts of each component in the laser - markable semi - transparent digital display polypropylene composite materials in Comparative Examples 1 - 6 are shown in Table 3 as follows.

[0055] Table 3 Laser - markable semi - transparent digital display polypropylene composite materials in Comparative Examples 1 - 6

[0056]

[0057] The performance test results of the laser - markable semi - transparent digital display polypropylene composite materials in each example and comparative example according to the method mentioned above are shown in Table 3.

[0058] Table 3 Test results of each example and comparative example

[0059]

[0060]

[0061] It can be seen from the data in Table 3 that the laser - markable semi - transparent digital display polypropylene composite material of the present invention has good digital display effect and excellent marking performance. The light transmittance reaches 3.04% - 37.58%, the clarity value is 75.3 - 86.8, and the color difference before and after marking is 37.35 - 45.7.

[0062] It can be found from Comparative Example 1 and Comparative Example 2 that when the light transmittance of the polypropylene resin with a thickness of 2mm < 60%, the light transmittance and clarity of the polypropylene composite material will be significantly reduced; when using hindered amine light stabilizers, the marking performance of the polypropylene composite material will be significantly reduced, which fully shows that not any light stabilizer can promote the improvement of the marking performance of the polypropylene composite material, that is, the type of light stabilizer has an important influence.

[0063] It can be seen from Comparative Example 3 and Comparative Example 4 that too much or too little addition amount of the light stabilizer is not conducive to improving the marking performance of the polypropylene composite material. When the addition amount of the light stabilizer is too little, the laser energy cannot be fully absorbed, resulting in a faint laser - engraved mark; when the addition amount of the light stabilizer is too much, too much laser energy is absorbed, resulting in a dark - yellowed laser - engraved mark, and at the same time, the transparency of the polypropylene composite material will be slightly reduced; it can be found from Comparative Example 5 and Comparative Example 6 that when the addition amount of the black colorant is too little, the marking performance of the polypropylene composite material will be greatly reduced; while when the addition amount of the black colorant is too much, it will significantly affect the light transmittance of the polypropylene composite material, thereby affecting its digital display effect.

[0064] The above embodiments of the present invention are merely examples for clearly illustrating the present invention, rather than limitations on the implementation manners of the present invention. For those of ordinary skill in the art, other different forms of changes or modifications can be made on the basis of the above description. It is not necessary and impossible to enumerate all implementation manners here. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the claims of the present invention.

Claims

1. A laser-markable semi-transparent digital-display polypropylene composite material, characterized in that, By weight parts, it includes the following components: 97 - 99.7 parts of polypropylene; 0.1 - 0.3 parts of antioxidant; 0.1 - 0.5 parts of lubricant; 0.1 - 1 part of light stabilizer; 0.001 - 0.1 part of black colorant; 0 - 0.1 part of white colorant; 0 - 0.2 part of organic pigment; The polypropylene adopts the ISO 13468 - 1:2019 standard, and the light transmittance with a thickness of 2 mm is ≥ 61%; the light stabilizer is at least one of benzotriazole light stabilizers and / or benzophenone light stabilizers; The black colorant is carbon black.

2. The semi-transparent digital display polypropylene composite material capable of being laser marked as described in claim 1, wherein The polypropylene adopts the ISO 13468 - 1:2019 standard, and the light transmittance with a thickness of 2 mm is 84% - 89%.

3. The laser-markable semi-transparent digital display polypropylene composite material according to claim 2, characterized in that, The polypropylene adopts the ASTM D - 1238 standard, and under the conditions of a temperature of 190 °C and a load of 2.16 kg, its melt mass flow rate is 12 - 65 g / 10 min.

4. The laser-markable semi-transparent digital-display polypropylene composite material according to claim 1, wherein The black colorant is 0.005 - 0.05 weight parts.

5. The laser-markable semi-transparent digital-display polypropylene composite material according to any one of claims 1 to 4, characterized in that The carbon black is acetylene carbon black; the white colorant is rutile titanium dioxide.

6. The laser-markable semi-transparent digital-display polypropylene composite material according to claim 5, characterized in that, The specific surface area of the black colorant is 60 to 200 m 2 / g.

7. The semi-transparent digital display polypropylene composite material capable of being laser marked according to any one of claims 1 to 4, characterized in that The specific surface area of the organic pigment is 10 to 60 m 2 / g.

8. The laser-markable semi-transparent digital display polypropylene composite material according to claim 7, characterized in that, The organic pigment is one or several of phthalocyanine pigments, quinacridone pigments or azo pigments.

9. A method for preparing the laser-markable semi-transparent digital-display polypropylene composite material according to any one of claims 1 to 8, characterized in that, It includes the following steps: Add polypropylene, antioxidant, lubricant, light stabilizer, black colorant, white colorant and organic pigment into an extruder, mix and then melt - extrude and pelletize to obtain the laser - markable semi - transparent digital display polypropylene composite material.

10. Use of the laser - markable semi - transparent digital display polypropylene composite material according to any one of claims 1 - 8 in the preparation of digital display components for household electrical appliances.

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