WO2013078902A1

WO2013078902A1 - Composition and shell and methods for preparing composition and shell

Info

Publication number: WO2013078902A1
Application number: PCT/CN2012/081839
Authority: WO
Inventors: Jianqiang LE; Pinshuang LAN; Jianghui Li
Original assignee: Shenzhen Byd Auto R&D Company Limited; Byd Company Limited
Priority date: 2011-11-28
Filing date: 2012-09-24
Publication date: 2013-06-06
Also published as: CN103131152B; CN103131152A

Abstract

A composition, a method of preparing the composition, a shell and a method of preparing the shell are provided. The composition comprises: a polycarbonate; and nano-particles of indium tin oxide dispersed in the polycarbonate. The shell comprises: a transparent polycarbonate layer; and a 3D pattern formed by blasted particles dispersed in the transparent polycarbonate layer, in which the blasted particles are formed by blasting nano-particles of indium tin oxide.

Description

COMPOSITION AND SHELL AND METHODS FOR PREPARING COMPOSITION AND

SHELL

FIELD

The present disclosure relates to a composition and a shell and methods of preparing the composition and the shell.

BACKGROUND

With the development of technology, laser inner carving appears. A planar pattern or a 3D (three dimensional) pattern may be carved inside a transparent material such as crystal or glass by laser inner carving, and the carved transparent material has better visual effect.

In recent years, with the development of mobile phone technology, customers have a higher requirement for the appearance of mobile phones. The graphic pattern and the decoration of mobile phones become more and more diverse. Those skilled in the art start to do research on the application of laser inner carving to mobile phones. Materials which may be processed by laser inner carving are glass and acrylic materials (polymethyl methacrylate (PMMA)).

However, glass and acrylic materials are brittle, which means that the notched impact strength of glass and acrylic materials is low. For example, the notched impact strength of polymethyl methacrylate is about 10kJ/m² to about 15kJ/m², and the notched impact strength of glass is lower than that of polymethyl methacrylate. Therefore, these two kinds of materials are usually applied to display protection screens of mobile phones, but may not be applied to mobile phone shells. However, a polycarbonate (PC) generally has a notched impact strength of about 60kJ/m² to about 70kJ/m², which may meet the requirement for mobile phone shells. However, the polycarbonate may not be processed by laser inner carving, which means that a planar pattern or a three dimensional pattern may not be carved inside a mobile phone shell made of PC.

SUMMARY

The object of the present disclosure is to solve at least one of the problems existing in the prior art to at least some extent, or to provide a consumer with a useful commercial choice.

Embodiments of a first aspect of the present disclosure provide a composition, comprising: a polycarbonate; and nano-particles of indium tin oxide dispersed in the polycarbonate.

Embodiments of a second aspect of the present disclosure provide a method of preparing a composition, comprising the steps of: mixing a polycarbonate and nano-particles of indium tin oxide to form a mixture; and extrusion molding the mixture to obtain the composition.

Embodiments of a third aspect of the present disclosure provide a shell, comprising: a transparent polycarbonate layer; and a 3D pattern formed by blasted particles dispersed in the transparent polycarbonate layer, in which the blasted particles are formed by blasting nano-particles of indium tin oxide.

Embodiments of a fourth aspect of the present disclosure provide a method of preparing a shell, comprising the steps of: molding a composition to form a shell, in which the composition comprises a polycarbonate and nano-particles of indium tin oxide dispersed in the polycarbonate; and irradiating the shell using a laser beam to form a 3D pattern.

According to embodiments of the present disclosure, the transparent polycarbonate is modified by adding nano-particles of indium tin oxide to the transparent polycarbonate to form the composition, and the composition may be processed by 3D laser inner carving. In addition, the notched impact strength of the composition is higher. The shell made of the composition may meet the requirements for 3D inner carved pattern decoration, and the impact strength of the shell may also meet the requirements for drop test.

Additional aspects and advantages of embodiments of present disclosure will be given in part in the following descriptions, become apparent in part from the following descriptions, or be learned from the practice of the embodiments of the present disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other aspects and advantages of examples of the present disclosure will become apparent and more readily appreciated from the following descriptions made with reference to the accompanying drawings, in which:

Fig. 1 is a schematic view of a shell according to a first embodiment of the present disclosure before processed by laser inner carving;

Fig. 2 is a schematic view of the shell according to the first embodiment of the present disclosure after processed by laser inner carving;

Fig. 3 is a schematic view of a shell according to a second embodiment of the present disclosure before processed by laser inner carving; and

Fig. 4 is a schematic view of the shell according to the second embodiment of the present disclosure after processed by laser inner carving.

DETAILED DESCRIPTION

Reference will be made in detail to embodiments of the present disclosure. The embodiments described herein with reference to drawings are explanatory, illustrative, and used to generally understand the present disclosure. The embodiments shall not be construed to limit the present disclosure. The same or similar elements and the elements having same or similar functions are denoted by like reference numerals throughout the descriptions.

According to an embodiment of the present disclosure, a composition is provided, comprising: a polycarbonate; and nano-particles of indium tin oxide dispersed in the polycarbonate.

As a person skilled in the art knows, polycarbonate (PC) is a commonly used material for a mobile phone shell in the prior art. During the research on 3D laser inner carving, the inventors find that the polycarbonate may be modified by adding nano-particles of indium tin oxide to the polycarbonate so as to obtain a modified polycarbonate, i.e., a composition. The composition may be used for preparing a shell. Because nano-particles of indium tin oxide may absorb ultrared rays, the nano-particles of indium tin oxide in the shell will blast to form a 3D pattern when the shell is irradiated by a laser beam which has a power higher than that of ultrared rays. Thus, a 3D inner carved pattern is formed in the shell. Moreover, nano-particles of indium tin oxide have little influence on the notched impact strength of the polycarbonate, and consequently the shell made of the composition according to an embodiment of the present disclosure has enough impact strength. In some embodiments, the polycarbonate is a transparent polycarbonate having a notched impact strength of about 40kJ/m² to about 75kJ/m². In order to present the 3D inner carved pattern inside the shell, the polycarbonate is a transparent polycarbonate. The transparent polycarbonate is a known material which may be commercially available. The notched impact strength of the transparent polycarbonate is about 40kJ/m² to about 75kJ/m², preferably about 60kJ/m² to about 75kJ/m², more preferably 60 kJ/m² or more. For example, the transparent polycarbonate may be PC Lexan EXRL 0672T from Sabic (Saudi Basic Industry Corporation), or PC Makrolon 2207T from Bayer (Friedr. Bayer et comp.).

The nano-particles of indium tin oxide are also a known material which may be commercially available. Nano-particles of indium tin oxide with outstanding ultrared ray absorbing performance are preferred. For example, the nano-particles of indium tin oxide may be VP AdNano ITO from EVONIK (Evonik Industries). Preferably, the nano-particles of indium tin oxide have an average particle diameter of about 80nm to about 100nm. Therefore, these nano-particles of indium tin oxide have better dispersion performance which may form finer 3D inner carved pattern.

In some embodiments, based on the total weight of the composition, the content of the nano-particles of indium tin oxide is about 5wt% to about 10wt%. If the content of the nano-particles of indium tin oxide is too high, the notched impact strength of the polycarbonate may be influenced, while if the content of the nano-particles of indium tin oxide is too low, abundant 3D inner carved pattern may not be formed.

In some embodiments, the composition further comprises a surface modifier coated on the surface of the nano-particles.

In the present disclosure, the nano-particles of indium tin oxide are used as an inorganic filler. The nano-particles of indium tin oxide may not be well compatible with the polycarbonate (PC), so it is preferred that modified nano-particles of indium tin oxide which have good compatibility with the polycarbonate (PC) are used as an inorganic filler. The method for preparing modified nano-particles of indium tin oxide is to coat the nano-particles of indium tin oxide with a surface modifier which may improve the compatibility of the nano-particles of indium tin oxide with polycarbonate (PC) material. Thus, the modified nano-particles of indium tin oxide will be more uniformly dispersed in the polycarbonate (PC). In addition, the surface modifier may activate the nano-particles of indium tin oxide to improve the compatibility of the nano-particles of indium tin oxide with the polycarbonate (PC).

In some embodiments, the surface modifier is preferably selected from the group consisting of vinyl methyl dimethoxy silane (trade name: A-2171 ), vinyl trimethoxy silane (trade name: A-171 ), γ-thiopropyl triethoxy silane (trade name: KH-591 ), and combinations thereof. These surface modifiers are colorless transparent sticky liquids which not only may make the nano-particles of indium tin oxide dispersed in the polycarbonate (PC) more uniformly but also may improve the compatibility between components in the system.

In some embodiments, based on the total weight of the composition, the content of the surface modifier is about 1wt% to about 3wt%.

It is necessary to explain that although the impact strength of the composition which is obtained by modifying the polycarbonate (PC) with the nano-particles of indium tin oxide will be reduced to a small extent compared with the compared with the polycarbonate (PC), the impact strength of the composition still may reach about 50kJ/m² to about 60kJ/m² which is far higher than the impact strength of polymethyl methacrylate (PMMA) and glass. The composition may be still used for preparing a shell.

According to an embodiment of the present disclosure, a method of preparing a composition is provided, comprising the steps of: mixing a polycarbonate and nano-particles of indium tin oxide to form a mixture; and extrusion molding the mixture to obtain the composition.

In the method for preparation the composition, in order to present the 3D inner carved pattern inside the shell better, the polycarbonate is a transparent polycarbonate. The transparent polycarbonate is a known material which may be commercially available. The transparent polycarbonate which has higher impact strength is preferred. For example, the transparent polycarbonate may be PC Lexan EXRL 0672 from Sabic (Saudi Basic Industry Corporation) which has a notched impact strength of about 74kJ/m², or PC Makrolon 2207 from Bayer (Friedr. Bayer et comp.) which has a notched impact strength of about 65kJ/m².

The nano-particles of indium tin oxide are also a known material which has outstanding ultrared ray absorbing performance. Preferably, the nano-particles of indium tin oxide have an average particle diameter of about 80nm to about 100nm. Therefore, these nano-particles of indium tin oxide have better dispersion performance which may form finer 3D inner carved pattern.

In some embodiments, prior to mixing the polycarbonate and nano-particles of indium tin oxide, the method of preparing the composition further comprises the step of: mixing the nano-particles and a surface modifier to form surface-modified nano-particles having the surface modifier coated on the surface of the nano-particles. This is because the nano-particles of indium tin oxide are used as an inorganic filler, and the nano-particles of indium tin oxide may not be well compatible with the polycarbonate (PC), so it is preferred that modified nano-particles of indium tin oxide which have good compatibility with the polycarbonate (PC) are used as an inorganic filler. The method for preparing modified nano-particles of indium tin oxide is to coat the nano-particles of indium tin oxide with a surface modifier which may improve the compatibility of the nano-particles of indium tin oxide with polycarbonate (PC) material. Thus, the modified nano-particles of indium tin oxide will be more uniformly dispersed in the polycarbonate (PC).

In some embodiments, based on the total weight of the composition, the content of the nano-particles of indium tin oxide is about 5wt% to about 10wt%.

In the method for preparation the composition, the nano-particles of indium tin oxide and the surface modifier are uniformly mixed by a high speed agitator to modify the nano-particles of indium tin oxide by coating the nano-particles of indium tin oxide with the surface modifier.

In some embodiments, the nano-particles of indium tin oxide, preferably the nano-particles of indium tin oxide coated with the surface modifier, and the PC are uniformly mixed by a high speed agitator to form a mixture. Then, the mixture is placed into a hopper of a double-screw extruder and extruded at an appropriate temperature under an appropriate pressure to prepare the composition.

Preferably, the extrusion molding is carried out in a double-screw extruder, the extrusion molding is carried out at a temperature of about 250°C to about 260°C, the extrusion molding is carried out under an extrusion pressure of about 1.8Mpa to about 3Mpa, the extrusion molding is carried out at a rotation speed of about 30r/min to about 40r/min, and the extrusion molding is carried out at a feeding rotation speed of about 9r/min to about 15r/min. The rotation speed means the rotate speed of a screw in the double-screw extruder, and the feeding rotation speed means the rotate speed of a screw in a feeding device.

The impact strength of the composition made by the abovementioned method will be reduced to a small extent compared with the polycarbonate (PC), but the impact strength of the composition still may reach about 50kJ/m² to about 60kJ/m², which may meet the application requirement for a shell.

According to an embodiment of the present disclosure, a shell is provided, comprising: a transparent polycarbonate layer; and a 3D pattern formed by blasted particles dispersed in the transparent polycarbonate layer, in which the blasted particles are formed by blasting nano-particles of indium tin oxide.

The shell is made of the composition. Because the nano-particles of indium tin oxide are dispersed in the transparent polycarbonate layer, the 3D pattern which is formed by blasting nano-particles of indium tin oxide is also dispersed in the transparent polycarbonate layer. So, the 3D pattern presents excellent visual effect, and the damage from scratches may be avoided effectively.

In order to make shell more beautiful, the electronic components in the mobile phone should be covered by the shell. Thus, preferably, the shell further comprises a non-transparent polycarbonate layer disposed below the transparent polycarbonate layer. The non-transparent polycarbonate layer is made of a common non-transparent polycarbonate which is known by a person skilled in the art. The non-transparent polycarbonate may be commercially available. Preferably, the non-transparent polycarbonate has high impact strength. For example, the non-transparent polycarbonate may be PC Lexan EXRL 0672 from Sabic (Saudi Basic Industry Corporation), or PC Makrolon 2207 from Bayer (Friedr. Bayer et comp.).

According to an embodiment of the present disclosure, a method for preparing a shell is provided, comprising the steps of: molding a composition to form a shell, in which the composition comprises a polycarbonate and nano-particles of indium tin oxide dispersed in the polycarbonate; and irradiating the shell using a laser beam to form a 3D pattern. Specifically, the method for preparing the shell comprises the following steps.

Step 1 : the abovementioned composition is molded to form a shell.

In this step, the composition comprises a polycarbonate and nano-particles of indium tin oxide dispersed in the polycarbonate. Preferably, the nano-particles of indium tin oxide are coated with a surface modifier.

The molding technique to form the shell may be a technique known by a person skilled in the art which may mold a plastic material (e.g., PC) to form a shell, such as injection molding. Preferably, the molding technique is injection molding, and consequently bicolor injection molding may be easy to perform. The technological conditions of injection molding may be changed according to practical requirements.

The composition should be dried at about 100°C to about 120°C for about 3 hours to about 4 hours before molding.

Step 2: the shell is irradiated using a laser beam generated by a laser inner carving machine, and the nano-particles of indium tin oxide blast to form a 3D pattern after absorbing the laser beam. Thus, the shell is formed.

In this step, taking advantage of the near-infrared light absorbing capability of nano-particles of indium tin oxide, when the power of the laser beam generated by the laser inner carving machine is higher than that of near-infrared light, the energy density of the laser beam partly focused on the transparent polycarbonate layer is greater than a critical value (also referred to as a threshold value) at which the nano-particles of indium tin oxide blast. Then, the nano-particles of indium tin oxide subtly blast to form white dots after getting energy, and thus a 3D pattern is formed.

The laser inner carving machine may use any laser device which may generate a laser beam having a power higher than that of near-infrared light. For example, the laser inner carving machine may be 3d sub-surface engraving series from CERION. The laser device may be 532nm Nd YAG Laser, preferably a green laser emitter which may generate a pulse laser beam.

In some embodiments, the laser beam is a pulse green laser beam. The pulse green laser beam has a power of about 100KW to about 500KW, an impulse frequency of about 1 kHz to about 10kHz and a pulse width of about 10ns to about 15ns.

The laser inner carving machine (e.g., Nd-YAG 532nm) may generate a pulse green laser beam. A laser inner carving machine which may generate ultraviolet rays may also be used. A laser inner carving machine which may generate a pulse green laser beam is preferred. The green laser emitter is applied more widely, and may not damage the shell because of high energy.

The 3D pattern may be designed according to practical requirements, and may be, for example, simple product LOGO or complicated decorative patterns. The method for manufacturing the 3D pattern is known by a person skilled in the art, and a detailed description thereof will be omitted here.

In some embodiments, the molding is carried out using a bicolor injection molding machine. The composition and the non-transparent polycarbonate are placed into the hopper of the bicolor injection molding machine respectively. In some embodiments, the method of preparing a shell further comprises: forming a top layer of transparent polycarbonate, and forming a bottom layer of non-transparent polycarbonate. Therefore, the shell made by the bicolor injection molding machine comprises a top layer of transparent polycarbonate and a bottom layer of non-transparent polycarbonate.

As mentioned above, according to embodiments of the present disclosure, the transparent polycarbonate is modified by adding nano-particles of indium tin oxide to the transparent polycarbonate to form the composition. Because the nano-particles of indium tin oxide may absorb near infrared light, the composition may be processed by 3D laser inner carving. Moreover, the notched impact strength of the composition is higher. The shell made of the composition may meet the requirements for 3D inner carved pattern decoration, and the impact strength of the shell may also meet the requirements for drop test. In addition, because the 3D inner carved pattern is located inside the shell, damages from scratches may be avoided effectively.

The present disclosure will be described below in more detail with reference to examples.

Example 1

This example is used to explain the composition and the method for preparing the composition, the shell and the method for preparing the shell according to embodiments of the present disclosure. 1 . Preparation of composition.

A. 10kg of a transparent polycarbonate, 500g of nano-particles of indium tin oxide and 500g of a transparent surface modifier were provided. The transparent polycarbonate was PC Lexan EXRL 0672T from Sabic. The notched impact strength of the transparent polycarbonate was 74kJ/m². The nano-particles of indium tin oxide was VP AdNano ITO from EVONIK. The surface modifier was vinyl methyl dimethoxy silane.

B. 500g of nano-particles of indium tin oxide and 500g of the transparent surface modifier were mixed uniformly by a high speed agitator to form a mixture. The surface modifier was coated on the surface of nano-particles of indium tin oxide to modify the nano-particles of indium tin oxide so as to improve the compatibility between the nano-particles of indium tin oxide and the polycarbonate. Then, the mixture obtained and 10kg of the transparent polycarbonate were mixed uniformly by the high speed agitator, and then placed into a hopper of a double-screw extruder and extrusion molded. The extrusion molding was carried out at a temperature of 250°C under an extrusion pressure of 1 .8Mpa at a rotation speed of 30r/min at a feeding rotation speed of 9r/min. After extrusion molding, 8kg of composition A1 was obtained.

The composition A1 was tested according to ASTM D256 standard or GB ISO 180 to determine the notched impact strength of the composition A1 . The test results were shown in Table 1 .

Table 1

As shown in Table 1 , the notched impact strength of the composition A1 is lower than that of PC Lexan EXRL 0672 which was not modified. However, the notched impact strength of the composition A1 may also meet the application requirement for a shell, since it is required that the notched impact strength of a material for a shell is not lower than 30kJ/m².

2. Forming of shell.

The shell was formed by bicolor injection molding in this example. The shell comprises two layers of polycarbonates, i.e., a top layer of composition A1 (i.e., a composition layer) and a bottom layer of non-transparent polycarbonate (i.e., a non-transparent polycarbonate layer). The non-transparent polycarbonate layer was made of PC Lexan EXRL 0672 from Sabic. The thickness of the top layer is 0.8mm, and the thickness of the bottom layer is 0.7mm.

The specific steps for forming the shell were as follows.

5kg of the composition A1 , 5kg of a non-transparent polycarbonate, a set of bicolor shell moulds and a bicolor injection molding machine were provided.

The composition A1 and the non-transparent polycarbonate were baked and dried at 100°C for 3 hours. Then, the non-transparent polycarbonate and the composition A1 were placed into a hopper of the bicolor injection molding machine. Molding was performed by using the bicolor shell moulds to obtain a shell B1 comprising a top layer of composition A1 (i.e., a composition layer) and a bottom layer of non-transparent polycarbonate (i.e., a non-transparent polycarbonate layer). As shown in Fig. 1 , the shell B1 comprises a non-transparent polycarbonate layer 11 and a composition layer disposed on the non-transparent polycarbonate layer 11 . The composition layer comprises a transparent polycarbonate layer 12 and nano-particles of indium tin oxide 13 dispersed in the transparent polycarbonate layer 12.

The process parameters of bicolor injection molding were shown in Table 2.

Table 2

3. Preparation of shell with 3D inner carved pattern.

A laser inner carving machine was provided, and a 3D pattern was designed. The 3D pattern was a 3D drawing in a file format of STL. The laser inner carving machine was 3d sub-surface engraving series from CERION. The laser device was 532nm Nd YAG Laser having three working shafts.

First, the 3D drawing was converted into a point cloud image by a professional point cloud conversion software, and the point cloud image was input into a computer marking software system. The shell B1 was placed on an operating platform and fastened by a clamp, with the transparent polycarbonate layer 12 facing upwards. Secondly, the computer marking software system was operated to control a galvanometer and the laser device to generate a pulse laser beam with a high pulse peak power of 300KW, a high pulse frequency of 5kHz and a pulse width of 10ns. The transparent polycarbonate layer 12 was irradiated by the pulse laser beam, the pulse laser beam was absorbed by nano-particles of indium tin oxide, and the nano-particles of indium tin oxide got energy and subtly blasted to form white dots so as to draw the outline of a 3D pattern.

The near infrared light absorbing capability of nano-particles of indium tin oxide was taken advantage of in this example. The laser beam generated by 532nm Nd YAG Laser was a pulse green laser beam. Because the power of the pulse green laser beam is higher than that of near infrared light, the energy density of the pulse laser beam partly focused on the transparent polycarbonate layer 12 is higher than a critical value (also referred to as a threshold value) at which the nano-particles of indium tin oxide blast. Finally, a shell C1 with a 3D inner carved pattern was obtained.

As shown in Fig. 2, the shell C1 with the 3D inner carved pattern comprises a non-transparent polycarbonate layer 11 and a composition layer disposed on the non-transparent polycarbonate layer 11 . The composition layer comprises a transparent polycarbonate layer 12 and blasted particles 13' formed by blasting the nano-particles of indium tin oxide and dispersed in the transparent polycarbonate layer 12. The blasted particles 13' form the 3D pattern. Because the 3D pattern is located inside the transparent polycarbonate layer 12, damages from scratches may be avoided effectively. Meanwhile, five falling ball impact test was performed for the shell C1 processed by laser inner carving.

The test results were shown in Table 3.

Table 3

As shown in Table 3, the impact strength of the shell C1 may meet the testing standard.

Example 2

This example is used to explain the composition and the method for preparing the composition, the shell and the method for preparing the shell according to embodiments of the present disclosure.

1 . Preparation of composition.

A. 10kg of a transparent polycarbonate, 500g of nano-particles of indium tin oxide and 500g of a transparent surface modifier were provided. The transparent polycarbonate was PC Makrolon 2207T from Bayer. The notched impact strength of the transparent polycarbonate was 65kJ/m². The nano-particles of indium tin oxide was VP AdNano ITO from EVONIK. The surface modifier was vinyl trimethoxy silane.

B. 500g of nano-particles of indium tin oxide and 500g of the transparent surface modifier were mixed uniformly by a high speed agitator to form a mixture. The surface modifier was coated on the surface of nano-particles of indium tin oxide to modify the nano-particles of indium tin oxide so as to improve the compatibility between the nano-particles of indium tin oxide and polycarbonate. Then, the mixture obtained and 10kg of the transparent polycarbonate were mixed uniformly by the high speed agitator, and then placed into a hopper of a double-screw extruder and extrusion molded. The extrusion molding was carried out at a temperature of 260°C under an extrusion pressure of 1 .8Mpa at a rotation speed of 30r/min at a feeding rotation speed of 9r/min. After extrusion molding, 8kg of composition A2 was obtained.

The composition A2 was tested according to ASTM D256 standard or GB ISO 180 to determine the notched impact strength of the composition A2. The test results were shown in Table 4.

Table 4

As shown in Table 4, the notched impact strength of the composition A2 is lower than that of PC Makrolon 2207 which was not modified. However, the notched impact strength of the composition A2 may also meet the application requirement for a shell, since it is required that the notched impact strength of a material for a shell is not lower than 30 kJ/m².

2. Forming of shell. The shell was formed by bicolor injection molding in this example. The shell comprises two layers of polycarbonates, i.e., a top layer of composition A1 (i.e., a composition layer) and a bottom layer of non-transparent polycarbonate (i.e., a non-transparent polycarbonate layer). The non-transparent polycarbonate layer was made of PC Makrolon 2207 from Bayer. The thickness of the top layer is 0.8mm, and the thickness of the bottom layer is 0.8mm.

5kg of the composition A2, 5 kg of a non-transparent polycarbonate, a set of bicolor shell moulds and a bicolor injection molding machine were provided. The composition A2 and the non-transparent polycarbonate were baked and dried at 100°C for 4 hours. Then, the non-transparent polycarbonate and the composition A2 were placed into a hopper of the bicolor injection molding machine. Molding was performed by using the bicolor shell moulds to obtain a shell B2 comprising a top layer of composition A2 (i.e., a composition layer) and a bottom layer of non-transparent polycarbonate (i.e., a non-transparent polycarbonate layer). The shell B2 comprises a non-transparent polycarbonate layer and a composition layer disposed on the non-transparent polycarbonate layer. The composition layer comprises a transparent polycarbonate layer and nano-particles of indium tin oxide dispersed in the transparent polycarbonate layer.

The process parameters of bicolor injection molding were shown in Table 5.

Table 5

Material Temperature/°C Time/S Pressure/kg/cm²

Mold Temperature of Press ur inject cooli inject Press ur backpres

(fixed hopper e ion ng ion e sure mould/m Je Fore Mid E maintai maintai oving t part die nd ning ning mould)

Compositi 120/100 31 310 305 30 1 0.42 7 2700 1800 65 on A2 0 5

Non-trans 120/100 32 320 312 31 1 0.4 7 2800 1900 60 parent 0 0

polycarbo

nate 3. Preparation of shell with 3D inner carved pattern.

First, the 3D drawing was converted into a point cloud image by a professional point cloud conversion software, and the point cloud image was input into a computer marking software system. The shell B2 was placed on an operating platform and fastened by a clamp, with the transparent polycarbonate layer facing upwards. Secondly, the computer marking software system was operated to control a galvanometer and the laser device to generate a pulse laser beam with a high pulse peak power of 300KW, a high pulse frequency of 10kHz and a pulse width of 10ns. The transparent polycarbonate layer was irradiated by the pulse laser beam, the pulse laser beam was absorbed by nano-particles of indium tin oxide, and the nano-particles of indium tin oxide got energy and subtly blasted to form white dots to draw the outline of a 3D pattern.

The near infrared light absorbing capability of nano-particles of indium tin oxide was taken advantage of in this example. The laser beam generated by 532nm Nd YAG Laser was a pulse green laser beam. Because the power of the pulse green laser beam is higher than that of near infrared light, the energy density of the pulse laser beam partly focused on the transparent polycarbonate layer is higher than a critical value (also referred to as a threshold value) at which the nano-particles of indium tin oxide blast. Finally, a shell C2 with a 3D inner carved pattern was obtained.

The shell C2 with the 3D inner carved pattern comprises a non-transparent polycarbonate layer and a composition layer disposed on the non-transparent polycarbonate layer. The composition layer comprises a transparent polycarbonate layer and blasted particles formed by blasting the nano-particles of indium tin oxide and dispersed in the transparent polycarbonate layer. The blasted particles form the 3D pattern. Because the 3D pattern is located inside the transparent polycarbonate layer, damages from scratches may be avoided effectively. Meanwhile, five falling ball impact test was performed for the shell C2 processed by laser inner carving. The test results were shown in Table 6. Table 6

As shown in Table 6, the impact strength of the shell C2 may meet the testing standard.

° Example 3

This example is used to explain the composition and the method for preparing the composition, the shell and the method for preparing the shell according to embodiments of the present disclosure. This example is similar to Example 1 , except that the shell in this example does not comprise a non-transparent polycarbonate layer. The method for ^ preparing the composition in this example is the same as that in Example 1 , but the method for preparing the shell in this example is different from that in Example 1 .

1 . Forming of shell.

The shell was formed by injection molding in this example. The shell comprises a composition layer, and the thickness of the composition layer is 0.8mm.

15 5kg of the composition A1 , a set of shell moulds and an injection molding machine were provided.

The composition A1 was baked and dried at 100°C for 3 hours. Then, the composition

A1 was placed into a hopper of the injection molding machine. Molding was performed by using the shell moulds to obtain a shell B3 comprising a composition layer.

20 As shown in Fig. 3, the shell B3 comprises a composition layer, and the composition layer comprises a transparent polycarbonate layer 21 and nano-particles of indium tin oxide 22 dispersed in the transparent polycarbonate layer 21 .

The process parameters of injection molding were shown in Table 7.

Table 7

Material Temperature/°C Time/S Pressure/kg/cm²

Mold Temperature of hopper Pressure injecti cooli injecti Pressure backpress

(fixed Jet Forep Middl En maintaini on ng on maintaini ure mould/mo art e d ng ng

ving mould)

Compositi 120/100 31 310 305 30 1 0.42 7 2700 1800 65 on A1 0 5

2. Preparation of shell with 3D inner carved pattern.

First, the 3D drawing was converted into a point cloud image by a professional point cloud conversion software, and the point cloud image was input into a computer marking software system. The shell B3 was placed on an operating platform and fastened by a clamp, with the transparent polycarbonate layer 21 facing upwards. Secondly, the computer marking software system was operated to control a galvanometer and the laser device to generate a pulse laser beam with a high pulse peak power of 300KW, a high pulse frequency of 5 kHz and a pulse width of 10ns. The transparent polycarbonate layer 21 was irradiated by the pulse laser beam, the pulse laser beam was absorbed by nano-particles of indium tin oxide, and the nano-particles of indium tin oxide got energy and subtly blasted to form white dots to draw the outline of a 3D pattern.

The near infrared light absorbing capability of nano-particles of indium tin oxide was taken advantage of in this example. The laser beam generated by 532nm Nd YAG Laser was a pulse green laser beam. Because the power of the pulse green laser beam is higher than that of near infrared light, the energy density of the pulse laser beam partly focused on the transparent polycarbonate layer 21 is higher than a critical value (also referred to as a threshold value) at which the nano-particles of indium tin oxide blast. Finally, a shell C3 with a 3D inner carved pattern was obtained.

As shown in Fig. 4, the shell C3 with the 3D inner carved pattern comprises a transparent polycarbonate layer 21 and blasted particles 22' formed by blasting the nano-particles of indium tin oxide and dispersed in the transparent polycarbonate layer 21. The blasted particles 22' form the 3D pattern. Because the 3D pattern is located inside the transparent polycarbonate layer 21 , damages from scratches may be avoided effectively. Meanwhile, five falling ball impact test was performed for the shell C3 processed by laser inner carving. The test results were shown in Table 8.

Table 8

As shown in Table 8, the impact strength of shell C3 may meet the testing standard.

As stated above, in the Examples 1-3 of the present disclosure, the transparent polycarbonate is modified by adding nano-particles of indium tin oxide to the transparent polycarbonate to form the composition. Because the nano-particles of indium tin oxide may absorb near infrared light, the composition may be processed by 3D laser inner carving. Moreover, the notched impact strength of the composition is higher. The shell made of the composition may meet the requirements for 3D inner carved pattern decoration, and the impact strength of the shell may also meet the requirements for drop test. In addition, because the 3D inner carved pattern is located inside the shell, damages from scratches may be avoided effectively.

Although explanatory embodiments have been shown and described, it would be appreciated by those skilled in the art that the above embodiments may not be construed to limit the present disclosure, and changes, alternatives, and modifications may be made in the embodiments without departing from spirit, principles and scope of the present disclosure.

Claims

WHAT IS CLAIMED IS:

1 . A composition, comprising:

a polycarbonate; and

nano-particles of indium tin oxide dispersed in the polycarbonate.

2. The composition of claim 1 , wherein the polycarbonate is a transparent polycarbonate having a notched impact strength of about 40kJ/m² to about 75kJ/m².

3. The composition of claim 1 , wherein the nano-particles have an average particle diameter of about 80nm to about 100nm.

4. The composition of claim 1 , wherein based on the total weight of the composition, the content of the nano-particles is about 5wt% to about 10wt%.

5. The composition of claim 1 or 3, further comprising a surface modifier coated on the surface of the nano-particles.

6. The composition of claim 5, wherein the surface modifier is selected from a group consisting of vinyl methyl dimethoxy silane, vinyl trimethoxy silane, γ-thiopropyl triethoxy silane, and combinations thereof.

7. The composition of claim 5, wherein based on the total weight of the composition, the content of the surface modifier is about 1wt% to about 3wt%.

8. A method of preparing a composition, comprising the steps of:

mixing a polycarbonate and nano-particles of indium tin oxide to form a mixture; and extrusion molding the mixture to obtain the composition.

9. The method of claim 8, prior to mixing the polycarbonate and nano-particles of indium tin oxide, further comprising the step of:

mixing the nano-particles and a surface modifier to form surface-modified nano-particles having the surface modifier coated on the surface of the nano-particles.

10. The method of claim 8, wherein based on the total weight of the composition, the content of the nano-particles is about 5wt% to about 10wt%.

11 . The method of claim 9, wherein based on the total weight of the composition, the content of the surface modifier is about 1wt% to about 3wt%.

12. The method of claim 8, wherein the extrusion molding is carried out in a double-screw extruder.

13. The method of claim 8, wherein the extrusion molding is carried out at a temperature of about 250°C to about 260°C.

14. The method of claim 8, wherein the extrusion molding is carried out under an extrusion pressure of about 1.8Mpa to about 3Mpa.

15. The method of claim 8, wherein the extrusion molding is carried out at a rotation speed of about 30r/min to about 40r/min.

16. The method of claim 8, wherein the extrusion molding is carried out at a feeding rotation speed of about 9r/min to about 15r/min.

17. A shell, comprising:

a transparent polycarbonate layer; and

a 3D pattern formed by blasted particles dispersed in the transparent polycarbonate layer,

wherein,

the blasted particles are formed by blasting nano-particles of indium tin oxide.

18. The shell of claim 17, further comprising a non-transparent polycarbonate layer disposed below the transparent polycarbonate layer.

19. A method of preparing a shell, comprising the steps of:

molding a composition to form a shell, wherein the composition comprises a polycarbonate and nano-particles of indium tin oxide dispersed in the polycarbonate; and irradiating the shell using a laser beam to form a 3D pattern.

20. The method of claim 19, wherein the molding is injection molding.

21 . The method of claim 20, wherein the molding is carried out using a bicolor injection molding machine.

22. The method of claim 19, further comprising forming a top layer of transparent polycarbonate.

23. The method of claim 19, further comprising forming a bottom layer of non-transparent polycarbonate.

24. The method of claim 19, wherein the laser beam is a pulse green laser beam.

25. The method of claim 24, wherein the pulse green laser beam has a power of about 100KW to about 500KW.

26. The method of claim 24, wherein the pulse green laser beam has an impulse frequency of about 1 kHz to about 10kHz.

27. The method of claim 24, wherein the pulse green laser beam has a pulse width about 10ns to about 15ns.