CN115991889A

CN115991889A - Polycarbonate article processing method

Info

Publication number: CN115991889A
Application number: CN202211278736.6A
Authority: CN
Inventors: 任天孝; 杨军成; 王博
Original assignee: Covestro Deutschland AG
Current assignee: Covestro Deutschland AG
Priority date: 2021-10-20
Filing date: 2022-10-19
Publication date: 2023-04-21

Abstract

The present invention relates to a method for processing polycarbonate articles. The method comprises the following steps: i) Forming marks and/or patterns on the surface of the polycarbonate substrate by ultraviolet laser engraving with the wavelength ranging from 315nm to 380 nm; and II) applying a protective layer having a transmittance of 20% or more for visible light on the surface of the polycarbonate substrate having the mark and/or pattern, wherein the polycarbonate substrate is made of a polycarbonate-based material having a transmittance of less than 80% for 355nm wavelength light at a thickness of 2 mm. The marks and/or patterns on the surface of the product processed by the method have high definition, good weather resistance and scratch resistance, and meet the long-term use requirement of the automobile interior and exterior products.

Description

Polycarbonate article processing method

Technical Field

The invention relates to the field of plastic product processing. In particular, the present invention relates to a method of processing polycarbonate articles.

Background

Polycarbonate (PC) is a lightweight, high-performance resin material having suitable toughness, dimensional stability, optical transparency and high heat resistance, and is widely used for manufacturing interior and exterior parts of automobiles.

With the development of 5G technology and the importance of the country to energy conservation and environmental protection, the automobile industry has seen new development trends in the past few years, such as interconnection, automatic driving and electric drive. These trends are changing the design of automotive interiors and exteriors. Manufacturers often need to integrate various indicia and design designs on the interior and exterior surfaces of molded parts, not only to take into account the properties of the parts (including mechanical, optical, wave-transparent, thermal insulation, etc.) but also to take into account the appearance of the parts.

Considering that automobiles are used in outdoor environments for a long time, the surfaces are often covered with a lot of dust and dirt, and the outer surfaces of the automobiles need frequent cleaning and brushing. Automotive exterior parts are required to be resistant to sunlight exposure and to high temperature and high humidity environments. The conventional process of machining indicia and patterns on the surface of molded parts includes: screen printing, water transfer printing film insert injection molding and the like. Although these processes have been well established and widely used, they have a number of drawbacks and limitations. For example: the screen printing process requires a plurality of processes to manufacture screen plates and steel plates with specific patterns, and once the patterns are manufactured, the patterns cannot be changed. The positioning accuracy of the pattern is poor during printing, and the definition of the edge of the pattern needs special ink to have good adhesion with the substrate, so that the printing can be performed only on a plane. The water transfer printing process needs to manufacture the polymer film with specific patterns through multiple procedures, the cost of the film is high, a complex production line is needed to realize continuous production, a large amount of water pollution exists in the production process, the subsequent treatment is needed, and printing can only be performed on some simple curved surfaces. The film insert injection molding process comprises the steps of printing patterns on the surface of a film by adopting a screen printing process, and then carrying out high-pressure forming and trimming on the film. The process is complex and the cost is high. The mold design is complex, the qualification rate of mass production is low, and the processing cost is high. The product is easy to have the apparent quality problems of wrinkling, ink flushing and the like.

In the field of electronics, infrared lasers are typically used for surface engraving when surface patterning is desired. It removes part of the material by heating and vaporizing (evaporating) the plastic surface, which is typically a heat treatment. Infrared laser engraving is typically performed using a YAG laser (wavelength 1.06 μm). Dark marks are formed on the surface of transparent plastic (e.g. polycarbonate) by the formation of a carbonized layer due to the thermal radiation of infrared laser. Ultraviolet laser engraving directly breaks molecular bonds on the surface of the polycarbonate through ultraviolet photons, so that molecules are separated from a matrix. Ultraviolet laser engraving does not generate high heat and is therefore called cold working. Ultraviolet laser engraving is not easy to make clear dark marks on the surface of transparent plastics (e.g. polycarbonate) because the carbonized layer cannot be formed due to the low energy radiation of ultraviolet laser (about 3-5W) compared to infrared laser (about 20W). The contrast of the pattern formed on the plastic surface by uv engraving with the substrate is not as great as that caused by ir engraving. Therefore, those skilled in the art often use infrared lasers to pattern surfaces on plastics.

Designs for some simple patterns also often employ patterning directly onto the mold surface, and then replicating the pattern on the mold onto the product surface by an injection molding process. Although this method can conveniently produce patterns on the surface of plastics, it has some disadvantages: 1) The manufacturing of the die is troublesome; 2) Various apparent quality problems such as flow marks, fusion lines and the like are very easy to occur in the injection molding process; 3) The pattern is monotonous; 4) The surface of the product is difficult to paint after molding; 5) The inability to protect such plastic articles with coatings results in articles prepared by this method having environmental resistance and durability that do not meet the weather or scratch resistance requirements of automotive exterior articles.

Accordingly, there remains a need in the art for a method of patterning the surface of a polycarbonate part that is simple in process, low in cost, stable in quality of the finished product, and good in durability.

Disclosure of Invention

An object of the present invention is to provide a method for patterning the surface of a polycarbonate part, which has the advantages of simple process, low cost, stable quality of the finished product and good durability.

Thus, according to a first aspect of the present invention, there is provided a method for processing a polycarbonate article, comprising the steps of:

i) Forming marks and/or patterns on the surface of the polycarbonate substrate by ultraviolet laser engraving with the wavelength ranging from 315nm to 380 nm; and

II) applying a protective layer having a transmittance of 20% or more for visible light, measured according to ISO 13468-2:1999, on the surface of the polycarbonate substrate having the marks and/or patterns,

wherein the polycarbonate substrate is prepared from a polycarbonate-based material having a transmittance of less than 80% at a thickness of 2mm for light having a wavelength of 355nm, as determined according to standard ISO 13468-2:1999.

According to a second aspect of the invention there is provided a polycarbonate article obtained by the method according to the first aspect of the invention.

The marks and/or patterns on the surface of the product obtained by the method have high definition, good weather resistance and scratch resistance, and meet the long-term use requirement of the automotive interior and exterior products.

Drawings

The invention is described and explained in more detail below with reference to the attached drawing figures, wherein:

FIG. 1 shows a photograph of sample S3-1 prepared in comparative example 3.

FIG. 2 shows a photograph of sample S3 'prepared in comparative example 3'.

Fig. 3 shows a photograph of sample S4 prepared in comparative example 4.

FIG. 4 shows a photograph of sample S5 prepared in inventive example 1.

Fig. 5 shows a photograph of sample S10 prepared in comparative example 9.

FIG. 6 shows a photograph of sample S11 prepared in inventive example 2.

Detailed Description

Some embodiments of the present invention will now be described in more detail for illustrative purposes with reference to the accompanying drawings.

According to a first aspect of the present invention, there is provided a method for processing a polycarbonate article, comprising the steps of:

Preferably, the polycarbonate-based material has a transmittance of less than 50%, more preferably less than 20%, at a thickness of 2mm for 355nm wavelength light.

The polycarbonate-based material is selected from materials having a polycarbonate content of at least 50 wt.%, relative to the total weight of the material.

Preferably, the polycarbonate-based material is selected from the group consisting of Polycarbonate (PC), polycarbonate-polyethylene terephthalate (PC-PET) alloy, polycarbonate-polybutylene terephthalate (PC-PBT) alloy, polycarbonate-poly (1, 4-cyclohexanedimethylene-1, 4-cyclohexanedicarboxylate) (PC-PCCD) alloy, polycarbonate-poly (ethylene terephthalate-1, 4-cyclohexanedimethanol) (PC-PETG) alloy, polycarbonate-poly (1, 4-cyclohexanedimethanol) polycarbonate-PCT alloy, polycarbonate-poly (acrylonitrile-butadiene-styrene) (PC-ABS) alloy, polycarbonate-poly (styrene-acrylonitrile) (PC-SAN) alloy, polycarbonate-poly (acrylonitrile-styrene-acrylate) (PC-ASA) alloy, and mixtures thereof.

The polycarbonate-based material may contain additives commonly used in the polycarbonate art including, but not limited to, toughening agents, antioxidants, colorants, and the like.

The type and amount of additives can be selected by those skilled in the art according to actual needs.

In some embodiments, the polycarbonate-based material further comprises at least one colorant. The colorant may include inorganic and/or organic dyes and/or pigments.

Preferably, a black pigment is used as a colorant, such as pigment carbon black (carbon black), aniline black, bone black, iron oxide black, spinel black and/or graphite, whereby a black opaque component is obtained.

The polycarbonate substrate may be prepared by processing techniques well known to those skilled in the art.

For example, the polycarbonate substrate may be processed by melt extrusion, injection molding, or the like.

The process for preparing the polycarbonate substrate is well known in the art and will not be described in detail herein.

The pattern or indicia may have any configuration, for example, two-dimensional geometric figures, pictograms, company or brand symbols, inscriptions in the form of letters and/or numbers, or combinations thereof. The resulting polycarbonate article may bear, for example, a manufacturer code, an authentication mark, a date of manufacture by means of the pattern or mark.

Uv laser engraving produces clear marks and/or images on the surface of a resin substrate by focusing a uv laser on the surface of the substrate.

Preferably, the ultraviolet laser engraving is performed under the following conditions:

wavelength: 315nm to 380nm, preferably 350 to 360nm, more preferably 355 nm;

engraving speed: 700-2000 mm/s;

power: 0.1-3 watts, preferably 0.5-3 watts.

The laser may be a continuous wave or pulsed wave type laser.

Preferably, the laser is a pulsed wave type laser, which is particularly advantageous for high power densities within the polymer matrix.

The pulse frequency is preferably 1kHz to 500kHz, more preferably 10kHz to 200kHz, and still more preferably 20 to 40kHz.

The pulse duration is preferably 5ns-300ns, more preferably 10ns-50ns, which is particularly advantageous for the power density of the laser during laser engraving.

The laser engraving is preferably performed using a solid state laser, such as a Nd: YAG laser, nd: cr: YAG laser, nd: ce: YAG laser, or Yb: YAG laser. It is particularly preferred to use, for example, semiconductor end-pumped lasers.

The laser engraving is operated by a rapid and non-contact technology, has obvious advantages in the aspect of marking speed compared with the traditional marking technology, and has the characteristics of environmental protection, safety, less maintenance and the like.

In many cases, laser marking uses less material and is much less costly than other marking methods.

Furthermore, the use of laser marking can also create marks and images on curved surfaces and difficult to reach areas. Preferably, the protective layer is formed from a silicone coating, a waterborne polyurethane coating, an acrylic coating, or a combination of the foregoing.

As commercial examples of the silicone coating, there may be mentioned products sold under the trade name SHC300 by the Michaelis high New Material group.

As commercial examples of the aqueous polyurethane coating, there may be mentioned products sold under the trade name RGFN-045R by Ningbo FuNa New Material Co.

As a commercial example of the acrylic paint, there may be mentioned a product sold under the trade name FNUV-0110 by Ningbo FuNa New Material Co.

Preferably, the thickness of the protective layer is in the range of 2-500 μm, more preferably the thickness of the protective layer is in the range of 2-50 μm.

Preferably, when a silicone coating is used, the thickness of the protective layer is between 2 and 10 μm.

Preferably, when an aqueous polyurethane coating is used, the thickness of the protective layer is 20-30 μm.

Preferably, when an acrylic coating is used, the thickness of the protective layer is between 2 and 20 μm.

Preferably, the protective layer has a transmittance of 50% or more, preferably 70% or more, more preferably 80% or more, and most preferably 90% or more for visible light.

The protective layer can protect the surface texture of the substrate.

In addition, the protective layer can realize scratch resistance, wear resistance, chemical resistance, ageing resistance and the like of the surface.

In some embodiments, the protective layer is applied directly on the surface of the polycarbonate substrate having the indicia and/or pattern.

When the protective layer is applied directly on the surface of the polycarbonate substrate having the indicia and/or pattern, no other layer is present between the polycarbonate substrate surface and the protective layer.

The article may be, for example, an automotive interior or exterior trim, such as a vehicle window, an exterior pillar, a front grille, an engine cover, a rear door, a vehicle lamp visor.

The descriptions of the features in the present application may be combined with each other without contradiction, and the resulting technical solutions fall within the scope of protection of the present application.

The terms "comprising" and "including" as used in this application encompass the situation in which other elements not explicitly mentioned are also included or included as well as the situation in which they consist of the elements mentioned.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. To the extent that the definitions of terms in this application are inconsistent with the ordinary meaning of those skilled in the art to which this invention pertains, the definitions described herein control.

Unless otherwise indicated, all numbers expressing thickness, size, processing conditions, and so forth used in the present application are to be understood as being modified by the term "about". Thus, unless indicated to the contrary, the numerical values set forth in the present application are approximations that may vary depending upon the desired properties to be obtained.

In the context of the present invention, "transparent" means that an observer can see through the sample and can recognize objects located behind the sample relative to the observer.

Examples

The conception and the technical effects of the present invention will be further described with reference to examples and drawings so that those skilled in the art can fully understand the objects, features and effects of the present invention. It will be readily appreciated by those skilled in the art that the embodiments herein are for illustrative purposes only and that the scope of the present invention is not limited thereto.

The raw materials used are as follows:

polycarbonate 0: colorless polycarbonate, available from kechuon polymer (china) limited under the trade name Makrolon 2405/55017, has a transmittance of 84% at a thickness of 2mm for light having a wavelength of 355 nm.

Polycarbonate 1: colorless transparent polycarbonate, obtained from the company Kogyo Polymer (China) under the trade name Makrolon AG2677/550396, has a transmittance of 0% at a thickness of 2mm for light having a wavelength of 355 nm.

Polycarbonate 2: black polycarbonate, obtained from kechuon polymer (china) limited under the trade name Makrolon AX2675/900346, has a transmittance of 0% at a thickness of 2mm in the 355nm wavelength band for light of 355nm wavelength.

Silicone coating: available from michaelcosis limited under the trade name PHC587C 2.

The equipment used is as follows:

an infrared laser: HANS K20-CS laser, supplied by the major family of laser technologies, inc.

Ultraviolet laser: HANS UV-3C laser, supplied by the major group laser technologies inc.

Comparative example 1 (CE 1)

Step 1: injection molding

Polycarbonate 1 was made into a tensile, impact sample S1 by an injection molding process according to the sample dimensions specified by standards ISO527-1-2-2012, ISO180-2000 and ISO 306-2013.

The injection molding process used was as follows:

a) Heating the mould temperature of the injection molding machine to 90-100 DEG C ^o The temperature in the range C and closing the mould,

b) Raising the temperature of a charging barrel of the injection molding machine to 280-300 ℃ and then cooling the charging barrel to the temperature of the charging barrel ^o C, injecting the molten thermoplastic resin into the cavity of the mould under the injection pressure of 70-110MPa,

c) Applying a pressure of 300-700 bar to the cavity for a period of time above 5 seconds,

d) Stopping the pressure to the cavity and at 90-100 DEG ^o Cooling for 20-30 seconds at the die temperature of C,

e) The mold was opened and the molded sample was removed.

Comparative example 2 (CE 2)

After injection molding of comparative example 1, step 2 was performed as follows, to obtain sample S2.

Step 2: infrared laser engraving

And visually inspecting the injection molded sample, and positioning the sample on an operating platform of the laser engraving machine after confirming that the surface of the injection molded sample has no obvious damage or sundries. And adjusting the focal length height of the laser spot according to the marking position of the sample. The laser engraving software was turned on and the parameters (wavelength, engraving density, speed, frequency and power, see table 1 below) were set and then the engraving command was performed. After the command execution is completed and the working window returns to the initial state, the sample is retrieved and the surface attachments (if necessary) are blown off by an air gun, and if necessary, the surface of the sample can be wiped by using dust-free cloth to be dipped with alcohol, so that a sample S2 is obtained.

TABLE 1

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Comparative example 3 (CE 3)

After step 1 of comparative example 1, step 2 was performed as follows, obtaining samples S3 and S3-1.

Step 2: ultraviolet laser engraving

And visually inspecting the injection molded sample, and positioning the sample on an operating platform of the laser engraving machine after confirming that the surface of the injection molded sample has no obvious damage or sundries. And adjusting the focal length height of the laser spot according to the marking position of the sample. The laser engraving software was turned on and the parameters (wavelength, engraving density, speed, frequency, power and pulse duration, see table 2 below) were set and then the engraving command was executed. After the command is executed and the working window returns to the initial state, the sample is retrieved and the surface attachments (if necessary) are blown off by an air gun, and if necessary, the surface of the sample can be wiped by using dust-free cloth to be dipped with alcohol, so that samples S3 and S3-1 are obtained, wherein S3 is marked with "wagen", and S3-1 has a square grid pattern, as shown in FIG. 1.

TABLE 2

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Comparative example 3 '(CE 3')

Comparative example 3' was performed with reference to comparative example 3, except that polycarbonate 0 was used as a raw material to obtain S3', wherein S3' has a checkered pattern as shown in fig. 2.

As can be seen from a comparison of fig. 1 and 2, the pattern obtained after uv engraving using polycarbonate 1 as a base material is clearer than the pattern obtained after uv engraving using polycarbonate 0 as a base material, and the uniformity of the pattern obtained by the latter is poor.

Comparative example 4 (CE 4)

After step 2 of comparative example 2, step 3 was performed as follows to obtain sample S4.

Step 3: applying a coating

The siloxane coating was applied to the surface of sample S2 using the shower coating process described below to form a coating of about 10 microns on the surface of the sample, resulting in sample S4.

And (3) a curtain coating process:

in a clean room, the sample is cleaned by cleaning with deionized wind to remove static electricity, and then the surface of the sample is cleaned with isopropanol. After the isopropanol is completely volatilized, the coating is coated on the surface of the sample in a curtain coating mode. At room temperature 23-25 ^o C. Flash-dry for 10 minutes at 35-55% humidity, then place the sample at 127 ^o And (C) baking in an oven for more than 40 minutes to obtain a final product.

Fig. 3 shows a photograph of sample S4 prepared in comparative example 4. As can be seen from the photographs, the marks on the resulting samples were clear and had no obvious defects.

Inventive example 1 (IE 1)

After step 2 of comparative example 3, step 3 was performed as follows, to obtain sample S5.

Step 3: applying a coating

The siloxane coating was applied to the surface of sample S3 using the shower coating process described below to form a coating of about 10 microns on the surface of the sample, resulting in sample S5.

And (3) a curtain coating process:

FIG. 4 shows a photograph of sample S5 prepared in inventive example 1. As can be seen from the photographs, the marks on the resulting samples were clear and had no obvious defects.

Comparative example 5 (CE 5)

After injection molding according to step 1 of comparative example 1, step 3 was performed as follows to obtain sample S6.

Step 3: applying a coating

The siloxane coating was applied to the surface of sample S1 using the shower coating process described below to form a coating of about 10 microns on the surface of the sample, resulting in sample S6.

And (3) a curtain coating process:

Comparative example 6 (CE 6)

Comparative example 6 was conducted with reference to comparative example 1 except that polycarbonate 2 was used instead of polycarbonate 1 to obtain sample S7.

Comparative example 7 (CE 7)

After step 1 of comparative example 6, step 2 was performed as follows, to obtain sample S8.

Step 2: infrared laser engraving

And visually inspecting the injection molded sample, and positioning the sample on an operating platform of the laser engraving machine after confirming that the surface of the injection molded sample has no obvious damage or sundries. And adjusting the focal length height of the laser spot according to the marking position of the sample. The laser engraving software was turned on and the parameters (wavelength, engraving density, speed, frequency, power and pulse duration, see table 1 above, except for 12W of power) were set and then the engraving command was executed. After the command execution is completed and the working window returns to the initial state, the sample is retrieved and the surface attachments (if necessary) are blown off by an air gun, and if necessary, the surface of the sample can be wiped by using dust-free cloth to be dipped with alcohol, so that a sample S8 is obtained.

Comparative example 8 (CE 8)

After step 1 of comparative example 6, step 2 was performed as follows, to obtain sample S9.

Step 2: ultraviolet laser engraving

And visually inspecting the injection molded sample, and positioning the sample on an operating platform of the laser engraving machine after confirming that the surface of the injection molded sample has no obvious damage or sundries. And adjusting the focal length height of the laser spot according to the marking position of the sample. The laser engraving software was turned on and the parameters (wavelength, engraving density, speed, frequency and power, see table 2 above) were set and then the engraving command was performed. After the command is executed and the working window returns to the initial state, the sample is retrieved and the surface attachments (if necessary) are blown off by an air gun, and if necessary, the surface of the sample can be wiped by using dust-free cloth to be dipped with alcohol, so that a sample S9 is obtained.

Comparative example 9 (CE 9)

After step 2 of comparative example 7, step 3 was performed as follows to obtain sample S10.

Step 3: applying a coating

The siloxane coating was applied to the surface of sample S8 using the shower coating process described below to form a coating of about 10 microns on the surface of the sample, resulting in sample S10.

And (3) a curtain coating process:

in a clean room, the sample is cleaned by cleaning with deionized wind to remove static electricity, and then the surface of the sample is cleaned with isopropanol. After the isopropanol is completely volatilized, the coating is coated on the surface of the sample in a curtain coating mode. At room temperature 23-25 ^o C. Flash-dry for 10 minutes at 35-55% humidity, then place the sample at 127 ^o And (C) baking in an oven for more than 40 minutes to obtain a sample S10.

Fig. 5 shows a photograph of sample S10 prepared in comparative example 9. As can be seen from the photographs, the marks on the resulting samples were clear and had no obvious defects.

Inventive example 2 (IE 2)

After step 2 of comparative example 8, step 3 was performed as follows to obtain sample S11.

Step 3: applying a coating

The siloxane coating was applied to the surface of sample S9 using the shower coating process described below to form a coating of about 10 microns on the surface of the sample, resulting in sample S11.

And (3) a curtain coating process:

in cleaningIn the clean room, the sample is cleaned by cleaning with deionized wind to remove static electricity, and then the surface of the sample is cleaned with isopropanol. After the isopropanol is completely volatilized, the coating is coated on the surface of the sample in a curtain coating mode. At room temperature 23-25 ^o C. Flash-dry for 10 minutes at 35-55% humidity, then place the sample at 127 ^o And (C) baking in an oven for more than 40 minutes to obtain a sample S11.

FIG. 6 shows a photograph of sample S11 prepared in inventive example 2. As can be seen from the photographs, the marks on the resulting samples were clear and had no obvious defects.

Comparative example 10 (CE 10)

After injection molding according to step 1 of comparative example 6, step 3 was performed as follows to obtain sample S12.

Step 3: applying a coating

The siloxane coating was applied to the surface of sample S7 using the shower coating process described below to form a coating of about 10 microns on the surface of the sample, resulting in sample S12.

And (3) a curtain coating process:

in a clean room, the sample is cleaned by cleaning with deionized wind to remove static electricity, and then the surface of the sample is cleaned with isopropanol. After the isopropanol is completely volatilized, the coating is coated on the surface of the sample in a curtain coating mode. At room temperature 23-25 ^o C. Flash-dry for 10 minutes at 35-55% humidity, then place the sample at 127 ^o And (C) baking in an oven for more than 40 minutes to obtain a sample S12.

Performance measurement

The mechanical properties (tensile modulus, tensile yield stress, tensile yield elongation, tensile breaking stress, tensile breaking elongation, impact strength at opening of cantilever Liang Moque, notched impact strength of cantilever beam) and vicat softening temperature of the samples S1 to S12 obtained above were tested. The results are shown in table 3.

Tensile modulus, tensile yield stress, tensile yield elongation, tensile breaking stress, tensile elongation at break: tests were performed according to standards ISO 527-1:2019 and ISO 527-2:2012.

Cantilever Liang Moque port impact strength: testing was performed according to standard ISO 180/U:2000+Amd.1:2006+Amd.2:2013.

Notched Izod impact Strength: tests were performed on 4mm and 3mm thickness samples according to standard ISO 180/A:2000+Amd.1:2006+Amd.2:2013.

Vicat softening temperature: the tests were carried out on samples of dimensions 80mm by 10mm by 4mm according to standard ISO 306:2013.

As can be seen from Table 3, the polycarbonate articles obtained in inventive example 1 and inventive example 2 have mechanical properties and thermal stability suitable for automotive interior and exterior applications.

Weather resistance

The weather resistance of the samples S1 to S12 obtained above was tested in an Atlas4000 xenon lamp aging oven according to the standard SAE J2527-2004 (xenon lamp aging test in dry and wet state). Test conditions: the illumination wavelength: 340nm; radiation intensity: 0.75w/cm ² The method comprises the steps of carrying out a first treatment on the surface of the Dry/wet time: 102/18min; total energy of radiation: 4500KJ. Irradiation intensity: 0.55W/m. The results are shown in table 4.

TABLE 4 Table 4

NA: not tested

According to the requirements of GMW14650:2021 automobile exterior trim after illumination:

appearance requirements: surface tackiness or embrittlement, hardness changes, halation, foaming or other factors which may affect the function or appearance of the product

Color change: delta E (+E) <3.0

The transmittance of the transparent template (S1-S6) is maintained: 95% or more

Gloss retention of black panels (S7-S12): at 60 ^o Is maintained in gloss by the observation angle of (a)>80%

As can be seen from table 4, the polycarbonate articles obtained in inventive example 1 and inventive example 2 have good appearance and light transmittance (or gloss) retention after illumination, indicating that they have good weatherability, satisfying the requirements of automotive exterior products.

Scratch resistance

The samples S1 to S12 obtained above were subjected to Talbot grinding wheel testing according to the standard ASTM D1044/DIN 52347. Test conditions: 500g load/500 revolutions. For the transparent samples (S1-S6), the father haze was tested; for the black panels (S7-S12), the father gloss was tested. The results are shown in table 5.

TABLE 5

NA: not tested.

For the transparent samples (S1-S6), the evaluation criterion was father haze <10%; for black panels (S7-S12), the criterion was father gloss <20%.

As can be seen from Table 5, the polycarbonate articles obtained in inventive example 1 and inventive example 2 have good scratch resistance, meeting the requirements of automotive exterior products.

Adhesion properties

The adhesion of the samples S4-S6, S10-S12 obtained above was tested according to standard ISO 2409:2020, and the adhesion between the polycarbonate substrate and the surface transparent hardened layer was tested. Test conditions: test with a griffe directly on the template and with 98 ^oC After 1-4 hours of boiling in water, cross-hatch test is carried out by using a hundred-cell knife. The results are shown in table 6.

TABLE 6

Characterization of "0": the bonding effect between PC and the hardening coating is the best;

characterization of "5": the adhesion between PC and the hardened coating was the worst.

As can be seen from Table 6, the polycarbonate molded articles obtained in invention example 1 and invention example 2 have good adhesion and meet the requirements of automotive interior and exterior products.

It can also be seen from Table 6 that the polycarbonate articles obtained in comparative example 4 and comparative example 9 were poor in adhesion between the carbonized layer and the transparent coating layer formed after infrared laser engraving, and could not meet the requirements of interior and exterior products.

Millimeter wave radar signal penetration performance

Millimeter wave radar signal penetration performance of the samples S1-S12 obtained above was tested according to the standard ICE 61189-2-721:2015 using a network analyzer from Keysight company in combination with a clamp of the free space method. Conditions are as follows: 77GHz millimeter wave radar signal. The results are shown in table 7.

TABLE 7

As can be seen from Table 7, the polycarbonate products obtained in invention example 1 and invention example 2 have good millimeter wave radar signal penetration performance, and meet the application requirements of the vehicle-mounted sensor.

In addition, the polycarbonate articles obtained in inventive example 1 and inventive example 2 gave very clear patterns after laser engraving on the surface of the polycarbonate substrate, and after protection of the patterns with a clear coating, had no adverse visual effect on the patterns themselves.

In summary, the polycarbonate product with the ultraviolet laser engraved pattern on the surface and the transparent coating protection completely meets the application requirements of the automobile interior and exterior trim.

Claims

1. A method of processing a polycarbonate article, comprising the steps of:

2. The method according to claim 1, wherein the polycarbonate-based material is selected from materials having a polycarbonate content of at least 50 wt% relative to the total weight of the material.

3. The method of claim 1 or 2, wherein the polycarbonate-based material is selected from the group consisting of polycarbonate, polycarbonate-polyethylene terephthalate alloy, polycarbonate-polybutylene terephthalate alloy, polycarbonate-poly (1, 4-cyclohexanedimethylene-1, 4-cyclohexanedicarboxylate) alloy, polycarbonate-poly (ethylene terephthalate-1, 4-cyclohexanedimethanol ester) alloy, polycarbonate-poly (1, 4-cyclohexanedimethanol terephthalate) alloy, polycarbonate-poly (acrylonitrile-butadiene-styrene) alloy, polycarbonate-poly (styrene-acrylonitrile) alloy, polycarbonate-poly (acrylonitrile-styrene-acrylate) alloy, and mixtures thereof.

4. A method according to any one of claim 1 to 3, wherein,

ultraviolet laser engraving was performed under the following conditions:

wavelength: 315nm to 380nm, preferably 350 to 360nm, more preferably 355 nm;

engraving speed: 700-2000 mm/s;

power: 0.1-3 watts, preferably 0.5-3 watts.

5. The method of any one of claims 1 to 4, wherein the laser is a continuous wave or a pulsed wave.

6. The method according to any one of claims 1 to 5, wherein the laser is a pulsed wave with a pulse frequency of 1kHz-500kHz, more preferably 10kHz-200kHz, more preferably 20-40kHz.

7. A method according to claim 6, characterized in that the pulse duration is 5ns-300ns, more preferably 10ns-50ns.

8. The method of any one of claims 1 to 7, wherein the protective layer is formed from a silicone coating, an aqueous polyurethane coating, an acrylic coating, or a combination thereof.

9. Method according to any one of claims 1 to 8, characterized in that the thickness of the protective layer is in the range of 2-500 μm, preferably in the range of 2-50 μm.

10. The method according to any one of claims 1 to 9, wherein the protective layer has a transmittance of visible light of equal to or greater than 50%, preferably equal to or greater than 70%, more preferably equal to or greater than 80%, most preferably equal to or greater than 90%.

11. The method according to any one of claims 1 to 10, characterized in that the protective layer is applied directly on the surface of the polycarbonate substrate having the marking and/or pattern.

12. A polycarbonate article processed by the method of any one of claims 1 to 11.

13. The polycarbonate article of claim 12, which is an automotive exterior trim selected from the group consisting of a vehicle window, an exterior pillar, a front grille, an engine cover, a rear door, a vehicle light visor.