WO2014139426A1

WO2014139426A1 - Composite material, substrate, shell for an electronic device and method of preparing the same

Info

Publication number: WO2014139426A1
Application number: PCT/CN2014/073294
Authority: WO
Inventors: Pinshuang LAN; Jianghui Li; Jianqiang LE; Xiaodong Zhang; Peng Ye
Original assignee: Shenzhen Byd Auto R&D Company Limited; Byd Company Limited
Priority date: 2013-03-12
Filing date: 2014-03-12
Publication date: 2014-09-18
Also published as: CN104045974B; CN104045974A

Abstract

The present disclosure discloses a composite material. The composite material contains an epoxy resin, a nylon, a curing agent and a mold release agent. The mold release agent contains polytetrafluoroethylene. A substrate including the composite material, a method for preparing the substrate, a shell of an electronic device including the substrate and a method for preparing the shell are also provided.

Description

COMPOSITE MATERIAL, SUBSTRATE, SHELL FOR AN ELECTRONIC DEVICE AND

METHOD OF PREPARING THE SAME

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to and benefits of Chinese Patent Application No.

201310077699.7, filed with the State Intellectual Property Office of P. R. China on March 12, 2013, the entire content of which is incorporated herein by reference.

FIELD

Exemplary embodiments of the present disclosure relate generally to a composite material, substrate and method of preparing the same, and a shell for an electronic device.

BACKGROUND

An epoxy resin is a widely used composite in shells of mobile phones. However, it is hard to mold composite materials to form snap joints directly. And epoxy resin is thermosetting, which is hard to be combined with other engineering plastics after cross-linking, such as PC. In addition, the adhesion between the epoxy resin and other materials is low, which does not meet the requirements in the manufacture of mobile phones. SUMMARY

Embodiments of the present disclosure seek to solve at least one of the problems existing in the prior art.

In one aspect of embodiments of the present disclosure, a composite material is provided. The composite material may contain an epoxy resin, a nylon, a curing agent and a mold release agent, in which the mold release agent contains polytetrafluoro ethylene.

The composite material according to embodiments of the present disclosure is easy to form snap joints and has better adhesion with other engineering plastics. In a molding process for a shell of an electronic device, snap joints may be formed on the shell through the in-mold decoration (IMD) using this composite material. As the composite material may have relative better adhesion with other plastics, such as the snap joints, plastic melting and fitting steps needed in a conventional process may be avoided. Further, there is no need to use additional mold release agent in the subsequent hot pressing step. In this way, the whole manufacturing cost for the composite material may be reduced significantly. In addition, the composite material may provide a shell with better appearance, without excessive glue phenomenon. Therefore the shell made by the composite material may have improved yield.

In another aspect of embodiments of the present disclosure, a method for preparing a substrate is provided. The method may include the steps of: applying the above-mentioned composite material on a surface of a fibrous fabric, and pre-curing the fibrous fabric applied with the composite material.

In yet another aspect of embodiments of the present disclosure, a substrate is provided. The substrate may be obtainable by the method for preparing the substrate mentioned above.

In a further aspect of embodiments of the present disclosure, a method for preparing a shell of an electronic device is provided. The method may include the steps of: providing the above-mentioned substrate, and subjecting the substrate to hot pressing and in-mold decoration using a plastic.

In yet another aspect of embodiments of the present disclosure, a shell of an electronic device is provided. The shell may be obtainable by the above-mentioned method for preparing the shell.

With the method for preparing the shell of the electronic device according to embodiments of the present disclosure, snap joints may be formed on the shell through IMD using this composite material. As the composite material may have relative better adhesion with other plastics, such as the snap joints, plastic melting and fitting steps needed in a conventional process may be avoided in this method. Further, there is no need to use additional mold release agent in the following hot pressing step in this method. In this way, the whole manufacturing cost for the method may be reduced significantly. In addition, the method may provide a shell with better appearance, without excessive glue phenomenon. Therefore the shell made by the method may have improved yield.

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 embodiments 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 substrate according to an embodiment of the present disclosure; and

Fig. 2 is a schematic view of a substrate according to another embodiment of the present disclosure.

DETAILED DESCRIPTION

Reference will be made in detail to embodiments of the present disclosure. The embodiments described herein 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.

For the purpose of the present description and of the following claims, the definitions of the numerical ranges always include the extremes unless otherwise specified.

According to embodiments of a first aspect of the present disclosure, a composite material is provided. The composite material may contain an epoxy resin, a nylon, a curing agent and a mold release agent, in which the mold release agent contains polytetrafluoro ethylene.

In one embodiment, based on the total weight of the composite material, the content of the epoxy resin is about 45% to about 62% by weight, the content of the nylon is about 25% to about 30%) by weight, the content of the curing agent is about 3% to about 5% by weight, and the content of the mold release agent is about 10% to about 20% by weight.

In one embodiment, based on the total weight of the composite material, the content of the polytetrafluoro ethylene is about 5% to about 10% by weight.

In one embodiment, the mold release agent may further contain an organic silicone resin.

In one embodiment, based on the total weight of the composite material, the content of the organic silicone resin may be about 5% to about 10% by weight.

In one embodiment, the composite material contains both the polytetrafluoro ethylene and the organic silicone resin. Based on the total weight of the composite material, the content of the polytetrafluoro ethylene is about 5% to about 10% by weight, and the content of the organic silicone resin is about 5% to about 10% by weight. By using the contents mentioned above, the adhesion between the composite material and a snap joint may be improved.

In one embodiment, the nylon has a melting temperature ranging from about 160°C to about 180°C. With this melting temperature, the temperature for baking the composite material may be reduced.

There is no special limit to the curing agent, provided the curing agent is capable of curing the composite material. For example, the curing agent may contain at least one selected from the group consisting of: dicyandiamide, aliphatic diamine, polyamine, organic acid anhydride and boron trifluoride.

In another aspect of embodiments of the present disclosure, a method for preparing a substrate is provided. The method may contain the steps of: applying the above mentioned composite material on a surface of a fibrous fabric; and pre-curing the fibrous fabric applied with the composite material.

In one embodiment of the present disclosure, the applying may be performed by electrostatic powder spraying.

In some embodiments of the present disclosure, the electrostatic powder spraying may be conducted under the conditions of: an atomization pressure ranging from about 0.30 MPa to about 0.45 MPa, a velocity pressure ranging from about 0.30 MPa to about 0.55 MPa, an electrostatic voltage ranging from about 60 kV to about 90 kV and an electrostatic current ranging from about 10 μΑ ίο about 20 μΑ.

In some embodiments of the present disclosure, based on the total weight of the substrate, the content of the composite material is about 40% to about 43% by weight. Then the intensity of the substrate may be improved.

In some embodiments of the present disclosure, the fibrous fabric may contain at least one selected from the group consisting of: carbon fiber fabric, aramid fiber fabric and glass fiber fabric. That is to say, the fibrous fabric may be made from at least one selected from carbon fiber, aramid fiber and glass fiber.

In another aspect of embodiments of the present disclosure, a method for preparing a shell of an electronic device is provided. The method may include the steps of: providing the substrate mentioned above, and subjecting the substrate to hot pressing and in-mold decoration (IMD, for example, in mold injection molding) using a plastic.

According to embodiments of the present disclosure, in the hot pressing step, main parts of the shell (for example, the substrate) of the electronic device may be formed; while in the IMD step, other parts of the shell, such as the snap joints which are used to connect the shell with another component of the electronic device, are formed on the shell with the plastic.

In some embodiments of the present disclosure, the hot-pressing is performed for about 8 min to about 10 min under a temperature of about 160 °C to about 180 °C and a pressure of about 1 MPa to about 3 MPa.

According to embodiments of the present disclosure, the plastic contains at least one of a copolymer of polyamide and glass fiber, and a copolymer of polyurethane and glass fiber. Then, the adhesion between the substrate and the snap joint may be improved.

According to a further aspect of the present disclosure, a shell of an electronic device is provided. The shell may be obtainable by the method for preparing the shell mentioned above.

It will be understood that the features mentioned above and those still to be explained hereinafter may be used not only in the particular combination specified but also in other combinations or on their own, without departing from the scope of the present disclosure.

Some illustrative and non-limiting examples are provided hereunder for a better understanding of the present invention and for its practical embodiment.

Embodiment 1

The present embodiment provides a shell of an electronic device and a method of preparing the same.

1) Preparing Composite Material

50 weight parts of epoxy resin, 28 weight parts of transparent nylon-12, 4 weight parts of curing agent (dicyandiamide), 8 weight parts of organic silicone resin and 10 weight parts of polytetrafluoro ethylene were mixed to form a composite material with a high-speed mixer.

2) Preparing Substrate

The composite material was applied onto a surface of a preimpregnated carbon fibrous fabric by electrostatic powder spraying under the conditions of: an atomization pressure of 0.45 MPa, a velocity pressure of 0.55 MPa, an electrostatic voltage of 80 kV and an electrostatic current of 15 μΑ. Then the carbon fibrous fabric applied with the composite material was pre-cured for 10 min at 60 °C in a drying oven to obtain the substrate. Based on the total weight of the substrate, the content of the composite material was 43% by weight.

3) Hot-pressing

The substrate was cut into proper shapes and placed in a hot pressing mould, and then subjected to a hot pressing step under the conditions of: a temperature of 180 °C, a pressure of 3 MPa and a pressure holding time of 10 min. Then the molded substrate was cooled.

4) Injection molding

Undesired flanges of the cooled substrate were removed by a CNC machine. And then said substrate was subjected to an in-mold injection molding using a copolymer of polyamide and glass fiber, obtaining a product Al . The product was used for the shell of the electronic device.

Embodiment 2

1) Preparing Composite Material

62 weight parts of epoxy resin, 25 weight parts of transparent nylon- 12, 3 weight parts of curing agent (aliphatic diamine), 5 weight parts of organic silicone resin and 5 weight parts of polytetrafluoro ethylene were mixed to form a composite material with a high-speed mixer.

2) Preparing Substrate

The composite material was applied onto a surface of a preimpregnated carbon fibrous fabric by electrostatic powder spraying under the conditions of: an atomization pressure of 0.30 MPa, a velocity pressure of 0.30 MPa, an electrostatic voltage of 60 kV and an electrostatic current of 10 μΑ. Then the carbon fibrous fabric applied with the composite material was pre-cured for 10 min at 80 °C in a drying oven to obtain the substrate. Based on the total weight of the substrate, the content of the composite material was 40% by weight.

3) Hot-pressing

The substrate was cut into proper shapes and placed in a hot pressing mould, and then subjected to a hot pressing step under the conditions of: a temperature of 160 °C, a pressure of 1 MPa and a pressure holding time of 10 min. Then the molded substrate was cooled.

4) Injection molding Undesired flanges of the cooled substrate were removed by a CNC machine. And then said substrate was subjected to an in-mold injection molding using a copolymer of polyamide and glass fiber, obtaining a product A2. The product was used for the shell of the electronic device. Embodiment 3

1) Preparing Composite Material

45 weight parts of epoxy resin, 30 weight parts of transparent nylon-12, 5 weight parts of curing agent (polyamine), 10 weight parts of organic silicone resin and 10 weight parts of polytetrafluoro ethylene were mixed to form a composite material with a high-speed mixer.

2) Preparing Substrate

The composite material was applied onto a surface of a preimpregnated carbon fibrous fabric by electrostatic powder spraying under the conditions of: an atomization pressure of 0.40 MPa, a velocity pressure of 0.40 MPa, an electrostatic voltage of 90 kV and an electrostatic current of 20 μΑ. Then the carbon fibrous fabric applied with the composite material was pre-cured for 10 min at 50 °C in a drying oven to obtain the substrate. Based on the total weight of the substrate, the content of the composite material was 42% by weight.

3) Hot-pressing

The substrate was cut into proper shapes and placed in a hot pressing mould, and then subjected to a hot pressing step under the conditions of: a temperature of 170 °C, a pressure of 2 MPa and a pressure holding time of 10 min. Then the molded substrate was cooled.

4) Injection molding

Undesired flanges of the cooled substrate were removed by a compact-cutting process. And then said substrate was subjected to an in-mold injection molding using a copolymer of polyamide and glass fiber, obtaining a product A3. The product was used for the shell of the electronic device.

Embodiment 4

1) Preparing Composite Material 60 weight parts of epoxy resin, 26 weight parts of transparent nylon- 12, 4 weight parts of curing agent (organic acid anhydride) and 10 weight parts of organic silicone resin were mixed to form a composite material with a high-speed mixer.

2) Preparing Substrate

The composite material was applied onto a surface of a preimpregnated aramid fibrous fabric by electrostatic powder spraying under the conditions of: an atomization pressure of 0.35 MPa, a velocity pressure of 0.50 MPa, an electrostatic voltage of 70 kV and an electrostatic current of 18 μΑ. Then the carbon fibrous fabric applied with the composite material was pre-cured for 10 min at 60 °C in a drying oven to obtain the substrate. Based on the total weight of the substrate, the content of the composite material was 41% by weight.

3) Hot-pressing

4) Injection molding

Undesired flanges of the cooled substrate were removed by a compact-cutting process. And then said substrate was subjected to an in-mold injection molding using a copolymer of polyamide and glass fiber, obtaining a product A4. The product was used for the shell of the electronic device. Embodiment 5

1) Preparing Composite Material

60 weight parts of epoxy resin, 30 weight parts of transparent nylon-12, 5 weight parts of curing agent (boron trifluoride) and 5 weight parts of organic silicone resin were mixed to form a composite material with a high-speed mixer.

2) Preparing Substrate

The composite material was applied onto a surface of a preimpregnated glass fibrous fabric by electrostatic powder spraying under the conditions of: an atomization pressure of 0.35 MPa, a velocity pressure of 0.45 MPa, an electrostatic voltage of 80 kV and an electrostatic current of 16 μΑ. Then the carbon fibrous fabric applied with the composite material was pre-cured for 10 min at 60 °C in a drying oven to obtain the substrate. Based on the total weight of the substrate, the content of the composite material was 43% by weight.

3) Hot-pressing

4) Injection molding

Undesired flanges of the cooled substrate were removed by a compact-cutting process. And then said substrate was subjected to an in-mold injection molding using a copolymer of polyamide and glass fiber, obtaining a product A5. The product was used for the shell of the electronic device.

Comparative Embodiment 1

This comparative embodiment provides a shell of an electronic device and a method of preparing the same in the prior art.

1) Hot-pressing

A fibrous fabric preimpregnated with epoxy resin was cut into proper shapes and placed in a hot pressing mould, and then subjected to a hot pressing under the conditions of: a temperature of 180°C, a pressure of 3MPa and a pressure holding time of lOmin. Then said fibrous fabric was cooled.

2) Forming Snap Joint

A copolymer of polyamide and glass fiber was subjected to an injection molding to obtain the snap joint.

3) Hot melting

Undesired flanges of the fibrous fabric obtained from the step 1) were removed by a CNC machine. Then said fibrous fabric and the snap joint were adhered with each other through a plastic melting and adhesion process using a hot melt adhesive, thus obtaining a product CA1. The product was used for the shell of the electronic device.

TESTS

1) Mechanical Property

1.1 Pull Strength Samples as shown in Fig. 1 were made based on the products Al-5 and CA1 (substrate- 1 and plastic-2). Then the pull strengths of these samples were tested with a universal testing machine, under a pull speed of 10 mm/min at two ends of each sample. The maximum pull strength occurred when the shell and the plastic separated from each other. The results were shown in table 1.

1.2 Shear Strength

Samples as shown in Fig. 2 were made based on the products Al-5 and CA1 (substrate- 1 and plastic-2). Then the shear strengths of these samples were tested with a universal testing machine, under a pull speed of 10 mm/min at two ends of each sample. The maximum shear strength occurred when the shell and the plastic separated from each other. The results were shown in Table 1.

1.3 Falling Time

Samples of the products A1-A5 and CA1 were fallen from 1 meter high, with a frequency of 12 times per minute. The falling was repeated until the sample was split. The number of falling times was recorded and the results were shown in Table 1.

2) Weatherability

2.1 Humidity Thermal Cycle

The samples of products of A1-A5 and CA1 were subjected to a cycle: at a high temperature of 55°C and a humidity ranging from 95%RH to 97%RH for 9 hours, and at a low temperature of 25°C and a humidity ranging from 95%RH to 97%RH for another 9 hours. The cycle was repeated until the sample was split. The number of cycles was recorded and the results were shown in Table 1.

2.2 Constant Temperature and Humidity

The samples of products of A1-A5 and CA1 were kept for 168 hours a temperature of 47°C and a humidity of 95%RH. Then the samples were observed, and details of whether these samples were split were recorded and the results were shown in Table 1.

2.3 Hot and Cold Cycle

The samples of products of A1-A5 and CA1 were subjected to a cycle: keeping at a high temperature of 65°C for 30min, and then at a low temperature of -40°C for 30min. The cycle was repeated until the sample was split. The number of cycles was recorded and the results were shown in Table 1. 2.4. Salt solution Corrosion

The samples of products of A1-A5 and CA1 were subjected to a salt solution (5% NaCl solution with a pH value ranging from 6.5 to 7.2) spraying for 2 hours at 35 °C. These samples were kept a temperature of 40 °C and a relative humidity of 80% for 168 hours. Then these samples were observed, and details of whether these samples were split were recorded and the results were shown in Table 1.

Table 1

As shown in table 1, the shells according to embodiments of the present disclosure may have a pull strength larger than 5.4MPa, a shear strength larger than 16.4 MPa, and will not spilt after falling from 1 meter high for 500 times. In comparison, the product CA1 made according to the Comparative Example has a pull strength as low as 1.6 MPa, a shear strength smaller than 5.6 MPa, and will split after falling from 1 meter time for 300 times. Therefore, it is clear that the shell according to embodiments of the present disclosure may have better mechanical performances and weatherability.

Many modifications and other embodiments of the present disclosure will come to mind to one skilled in the art to which the present disclosure pertains having the benefit of the teachings presented in the foregoing description. It will be apparent to those skilled in the art that variations and modifications of the present disclosure can be made without departing from the scope or spirit of the present disclosure. Therefore, it is to be understood that the disclosure is not to be limited to the specific embodiments disclosed and that modifications and other embodiments are intended to be included within the scope of the appended claims. Although specific terms are employed herein, they are used in a generic and descriptive sense only and not for purposes of limitation.

Claims

What is claimed is:

1. A composite material comprising:

an epoxy resin;

a nylon;

a curing agent; and

a mold release agent,

wherein the mold release agent comprises polytetrafluoro ethylene.

2. The composite material according to claim 1, wherein based on the total weight of the composite material, the content of the epoxy resin is about 45% to about 62% by weight, the content of the nylon is about 25% to about 30% by weight, the content of the curing agent is about 3%) to about 5%) by weight, and the content of the mold release agent is about 10%> to about 20%> by weight.

3. The composite material according to claim 1 or 2, wherein based on the total weight of the composite material, the content of the polytetrafluoro ethylene is about 5% to about 10% by weight.

4. The composite material according to any one of claims 1-3, wherein the mold release agent further comprises an organic silicone resin.

5. The composite material according to claim 4, wherein based on the total weight of the composite material, the content of the organic silicone resin is about 5% to about 10% by weight.

6. The composite material according to any one of claims 1-5, wherein the nylon has a melting temperature ranging from about 160°C to about 180°C.

7. The composite material according to any one of claims 1-6, wherein the curing agent comprises at least one selected from the group consisting of dicyandiamide, aliphatic diamine, polyamine, organic acid anhydride and boron trifluoride.

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

applying a composite material according to any one of claims 1-7 on a surface of a fibrous fabric; and

pre-curing the fibrous fabric applied with the composite material.

9. The method according to claim 8, wherein the applying is performed by electrostatic powder spraying.

10. The method according to claim 9, wherein the electrostatic powder spraying is conducted under the conditions of:

an atomization pressure ranging from about 0.30 MPa to about 0.45 MPa,

a velocity pressure ranging from about 0.30 MPa to about 0.55 MPa,

an electrostatic voltage ranging from about 60 kV to about 90 kV, and

an electrostatic current ranging from about 10 μΑ to about 20 μΑ.

11. A substrate obtainable by the method according to any one of claims 8-10.

12. The substrate according to claim 11, wherein based on the total weight of the substrate, the content of the composite material is about 40% to about 43% by weight.

13. The substrate according to claim 11 or 12, wherein the fibrous fabric comprises at least one selected from the group consisting of: carbon fiber fabric, aramid fiber fabric and glass fiber fabric.

14. A method for preparing a shell of an electronic device, comprising the steps of:

providing a substrate according to any one of claims 11-13, and

subjecting the substrate to hot pressing and in-mold decoration using a plastic.

15. The method according to claim 14, wherein the hot-pressing is performed for about 8 min to about 10 min under a temperature of about 160 °C to about 180 °C and a pressure of about 1 MPa to about 3 MPa.

16. The method according to claim 14 or 15, wherein the plastic comprises at least one of a copolymer of polyamide and glass fiber, and a copolymer of polyurethane and glass fiber.

17. A shell of an electronic device obtainable by the method according to any one of claims 14-16.