White polycarbonate composition as well as preparation method and application thereof

Abstract

The invention relates to a white polycarbonate composition as well as a preparation method and application thereof. The white polycarbonate composition comprises the following components in parts by weight: 75-97 parts of polycarbonate, 3-8 parts of titanium dioxide and 0.1-1 part of copper hydroxide. A certain amount of titanium dioxide is added into polycarbonate, so that the white polycarbonate composition is white. The average particle size of the titanium dioxide is regulated and controlled within a specific range, light reflection of the white polycarbonate composition can be reduced, so that more laser is absorbed, more heat is released, and the laser welding strength is improved to a certain extent. On the basis of regulating and controlling the average particle size of the titanium dioxide, the linear copper hydroxide is added, so that the laser welding strength of the white polycarbonate composition can be obviously improved on the premise of not influencing the white color of the white polycarbonate composition.

Description

Technical Field

[0001] The present invention relates to the technical field of laser plastic welding, and more specifically, to a white polycarbonate composition, a preparation method thereof, and an application thereof. Background Art

[0002] Polycarbonate (PC) is a common engineering plastic with excellent mechanical properties and heat resistance, having advantages such as high strength and elastic modulus, high impact strength, high heat resistance, free dyeability, low molding shrinkage rate, good dimensional stability, and good fatigue resistance. Modified PC products are widely used in many fields such as automotive parts, industrial machinery parts, optical discs, packaging, office equipment such as computers, medical care, films, leisure, and protective equipment. With the improvement of the complexity and integration of product structures, simple injection molding processes alone can no longer meet the requirements, and different parts often need to be connected. Laser welding is an economical and environmentally friendly new plastic processing and connection method. Laser welding uses high-energy laser as a heat source, and has characteristics such as fast speed, fine structure, small heat-affected zone, and good forming compared with traditional welding methods.

[0003] Laser welding usually includes a light-transmitting layer (light-transmitting member) and a light-absorbing layer (light-absorbing member). The absorbing layer absorbs the laser and releases heat to form a heat-affected zone nearby. The two plastic sheets are strongly bonded together under the action of pressure and thermal expansion, thus being welded together. In addition, the materials for laser welding should maintain a small reflectivity, because if the reflectivity is too large, the input energy needs to be increased during the welding process.

[0004] In the prior art, polycarbonate materials with a bias towards black are often used as the light-absorbing layer. For example, a Chinese patent for a polycarbonate composition that is easy to process by laser welding and a preparation method thereof discloses that in the presence of a near-infrared laser absorber (such as carbon black), the melt strength and welding strength of the polycarbonate composition are improved by adding a melt-strengthening agent, and the polycarbonate composition of this patent is biased towards black.

[0005] White polycarbonate materials (L value ≥ 94) have a wide range of uses. When laser welding with a transparent member, if the white polycarbonate material is used as the light-absorbing layer, it is often difficult to absorb the laser and has a large reflectivity, resulting in low laser welding strength, which limits the applicability of the laser welding process to white polycarbonate materials.

[0006] Currently, there are few reports on using white polycarbonate materials as the light-absorbing layer and then laser welding with a transparent member. Therefore, it is necessary to develop a white polycarbonate material for laser welding suitable for the light-absorbing layer to meet the current market demand. Summary of the Invention

[0007] The primary object of the present invention is to overcome the problem of the lack of white polycarbonate materials for laser welding suitable for the light-absorbing layer, and to provide a white polycarbonate composition.

[0008] A further object of the present invention is to provide a method for preparing the above-mentioned white polycarbonate composition.

[0009] Another object of the present invention is to provide the application of the above-mentioned white polycarbonate composition in the preparation of white product components.

[0010] The above objects of the present invention are achieved by the following technical solutions:

[0011] A white polycarbonate composition, comprising the following components in parts by weight: 75-97 parts of polycarbonate, 3-8 parts of titanium dioxide, and 0.1-1 part of copper hydroxide;

[0012] The average particle size of the titanium dioxide ≤ 100 nm;

[0013] The copper hydroxide is nanowire-shaped.

[0014] In the present invention, a certain amount of titanium dioxide is added to the polycarbonate, so that the white polycarbonate composition presents white (L value is above 94).

[0015] The inventors of the present invention have found through research that by regulating the average particle size of titanium dioxide within a specific range, the reflection of light by the white polycarbonate composition can be reduced, so that more laser light is absorbed and more heat is released, thereby improving the laser welding strength to a certain extent.

[0016] The inventors of the present invention further found through research that on the basis of regulating the average particle size of titanium dioxide, adding nanowire-shaped copper hydroxide can significantly improve the laser welding strength of the white polycarbonate composition without affecting the whiteness of the white polycarbonate composition. The reason is that: on the one hand, there is a π-π transition in the characteristic absorption band of nanowire-shaped copper hydroxide, and a strong L→M charge transfer transition occurs in the central metal ion Cu within the laser wavelength range, forming a relatively strong laser absorption; on the other hand, due to the quantum size effect and surface effect of nanowire-shaped copper hydroxide, it has a large specific surface area and good absorption activity. The combined effect of the two aspects greatly improves the laser absorption ability of the white polycarbonate composition, causing the molecular chains to vibrate and melt, further improving the laser welding strength. 2+ ... undergoes an L→M charge transfer transition, forming a relatively strong laser absorption; on the other hand, due to the quantum size effect and surface effect of nanowire-shaped copper hydroxide, it has a large specific surface area and good absorption activity. The combined effect of the two aspects greatly improves the laser absorption ability of the white polycarbonate composition, causing the molecular chains to vibrate and melt, further improving the laser welding strength.

[0017] In the present invention, polycarbonate is used as the main resin. Preferably, its content accounts for more than 75 wt% of the white polycarbonate composition.

[0018] Preferably, the viscosity-average molecular weight of the polycarbonate is 20,000-30,000.

[0019] In the present invention, the viscosity-average molecular weight of the polycarbonate is measured by gel permeation chromatography, and the test standard is GB / T21863-2008.

[0020] Preferably, the polycarbonate is an aromatic polycarbonate.

[0021] More preferably, the aromatic polycarbonate is a bisphenol A polycarbonate.

[0022] Preferably, the average diameter of the copper hydroxide is 4 to 80 nm, and the average length is 150 to 1200 nm.

[0023] More preferably, the average length of the copper hydroxide is 600 to 800 nm. When the average length of the copper hydroxide is controlled within this range, the white polycarbonate composition has higher laser welding strength.

[0024] In the present invention, the average diameter of the copper hydroxide can be measured according to GB / T 26826-2011.

[0025] In the present invention, the average length of the copper hydroxide can be measured according to GB / T 30543-2014.

[0026] Preferably, the white polycarbonate composition further comprises the following components in parts by weight: 0.001 to 0.008 parts of carbon black.

[0027] More preferably, the average particle size of the carbon black is 34 to 55 nm.

[0028] Further preferably, the average particle size of the carbon black is 40 to 47 nm. Controlling the average particle size of the carbon black within the range of 40 to 47 nm is beneficial to improving the laser absorption ability of the white polycarbonate composition, thereby enhancing the laser welding strength.

[0029] In the present invention, the average particle size of the carbon black is measured by laser diffraction method, the dispersion medium is water, and the measurement standard is GB / T19077.1-2008.

[0030] More preferably, the oil absorption value of the carbon black is 48 to 122.

[0031] More preferably, the type of the carbon black is furnace black.

[0032] In the present invention, the oil absorption value of the carbon black can be measured according to ISO 787-5-1995.

[0033] Preferably, the crystal form of the titanium dioxide is rutile type.

[0034] Preferably, the white polycarbonate composition further comprises the following components in parts by weight: 0.3 to 3 parts of other additives.

[0035] More preferably, the other additives are at least one of an antioxidant, a lubricant or an anti-UV agent.

[0036] Further preferably, the antioxidant is at least one of antioxidant 1010, antioxidant 1076 or antioxidant 1098.

[0037] Further preferably, the lubricant is at least one of pentaerythritol tetrastearate, glycerol monostearate or glycerol tristearate.

[0038] Further preferably, the anti-UV agent is at least one of UV-234, UV-5411 or UV-239.

[0039] The preparation method of the above-mentioned white polycarbonate composition comprises the following steps: weighing each component according to the formula and mixing, followed by melt extrusion and granulation to obtain the white polycarbonate composition.

[0040] Preferably, the melt extrusion is carried out in an extruder.

[0041] More preferably, the screw speed of the extruder is 300 - 600 revolutions per minute, the screw length-diameter ratio is (35 - 48):1, and the temperature is 240 - 290 °C.

[0042] The application of the above-mentioned white polycarbonate composition in the preparation of white product parts is also within the protection scope of the present invention.

[0043] Preferably, the white product part is a light-absorbing part for laser welding.

[0044] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0045] In the present invention, a certain amount of titanium dioxide is added to the polycarbonate, so that the white polycarbonate composition presents white (L value above 94). By controlling the average particle size of the titanium dioxide within a specific range, the reflection of light by the white polycarbonate composition can be reduced, so that more laser light is absorbed and more heat is released, thereby improving the laser welding strength to a certain extent. On the basis of controlling the average particle size of the titanium dioxide, adding nanowire-like copper hydroxide can significantly improve the laser welding strength of the white polycarbonate composition without affecting the whiteness of the white polycarbonate composition. Detailed Embodiments

[0046] In order to more clearly and completely describe the technical solution of the present invention, the present invention is further described in detail below through specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention, and various changes can be made within the scope defined by the rights of the present invention.

[0047] Some of the reagents selected in the embodiments and comparative examples of the present invention are described as follows:

[0048] Polycarbonate 1#: The viscosity-average molecular weight is 23,000, S-2000F, Mitsubishi, Japan;

[0049] Polycarbonate 2#: The viscosity-average molecular weight is 28,000, PC E-2000F, Mitsubishi, Japan;

[0050] Polycarbonate 3#: The viscosity-average molecular weight is 20,000, 1201-22, LG, South Korea;

[0051] Titanium Dioxide 1#: The average particle size is 75 nm, and the crystal form is rutile type;

[0052] Titanium Dioxide 2#: The average particle size is 25 nm, and the crystal form is rutile type;

[0053] Titanium Dioxide 3#: The average particle size is 30 nm, and the crystal form is rutile type;

[0054] Titanium Dioxide 4#: The average particle size is 200 nm, and the crystal form is rutile type;

[0055] Copper Hydroxide 1-3#: Linear shape, self-made, prepared according to the reference "Preparation and Characterization of Copper Hydroxide Nanowires" (DOI: 10.16039 / j.cnki.cn22-1249.2016.07.015.). Among them, the average length is achieved by regulating the concentration and volume of the sodium hydroxide solution. The average diameter of Copper Hydroxide 1-3# is 5 nm, and the average lengths are 800 nm, 600 nm, and 1000 nm respectively.

[0056] Copper Hydroxide 4#: Linear shape, the average diameter is 60 nm, the average length is 150 nm, Changhu Nano Technology, Suzhou;

[0057] Copper Hydroxide 5#: Granular shape, the average particle size is 150 nm, Copper Hydroxide, Wujiang Yongsheng Chemical Co., Ltd.;

[0058] Nickel Hydroxide: Linear shape, the average diameter is 40 nm, the average length is 50 μm, XFJ39, Jiangsu Xianfeng Nano Materials Technology Co., Ltd.;

[0059] Carbon Black 1#: The type of carbon black is furnace black, and the average particle size is 40 nm;

[0060] Carbon Black 2#: The type of carbon black is furnace black, and the average particle size is 55 nm;

[0061] Carbon Black 3#: The type of carbon black is furnace black, and the average particle size is 47 nm;

[0062] Carbon Black 4#: The type of carbon black is furnace black, and the average particle size is 45 nm;

[0063] Other Auxiliary 1#: Antioxidant, antioxidant 1010, commercially available;

[0064] Other Auxiliary 2#: Lubricant, pentaerythritol stearate, commercially available;

[0065] Other Auxiliary 3#: UV-resistant agent, UV-234, commercially available.

[0066] Unless otherwise specified, the components selected in each parallel example and comparative example (such as Other Auxiliary 1#) are all the same commercially available products.

[0067] The white polycarbonate compositions of each example and comparative example of the present invention are prepared through the following process: Weigh each component according to the formula and mix them evenly, then feed them into the main feeding port of a twin-screw extruder, melt and blend them, and extrude and pelletize them to obtain the white polycarbonate composition.

[0068] Among them, the temperature of the first zone of the twin-screw extruder is 250 °C, the temperature of the second zone is 250 °C, the temperature of the third zone is 240 °C, the temperature of the fourth zone is 240 °C, the temperature of the fifth zone is 240 °C, the temperature of the sixth zone is 240 °C, the temperature of the seventh zone is 240 °C, the temperature of the eighth zone is 240 °C, the temperature of the ninth zone is 250 °C, and the temperature of the tenth zone is 250 °C; the screw speed of the twin-screw extruder is 450 revolutions per minute, and the length-diameter ratio of the screw is 40:1.

[0069] The performance test methods and standards of the white polycarbonate compositions of each example and comparative example of the present invention are as follows:

[0070] (1) Whiteness: Test with a Color-Eye7000A device, and the obtained L value is used to represent the whiteness, referring to the standard GB / T 7921-2008;

[0071] (2) Laser welding strength: Cut the injection-molded sheet 100×100×3 mm into 100×20×3 mm size, perform laser welding on a YH-PLW100-300A laser welding machine of Shenzhen Bote Precision Equipment Technology Co., Ltd., and then refer to ISO 527-2012 to test the tensile strength of the specimen as the evaluation parameter of the laser welding strength of the specimen. The light-transmitting layer is made of PC1250Y injection-molded into 100×100×3 mm and cut into 100×20×3 mm size.

[0072] (3) Reflectivity: Test the injection-molded sheet 100×100×3 mm with an ultraviolet-visible-near-infrared spectrometer (Lambda900) at 960 nm, specifically referring to the test standard ASTM F1252-89.

[0073] Examples 1 to 14

[0074] Examples 1 to 14 provide a series of white polycarbonate compositions, and the weight parts of each component in the formula are shown in Tables 1 and 2.

[0075] Table 1 Formulations of Examples 1 to 7

[0076] Example 1 2 3 4 5 6 7 Polycarbonate 1# 89 78 96.8 / / 89 89 Polycarbonate 2# / / / 89 / / / Polycarbonate 3# / / / / 89 / / Titanium Dioxide 1# 5 7 3 5 5 / / Titanium Dioxide 2# / / / / / 5 / Titanium Dioxide 3# / / / / / / 5 Copper Hydroxide 1# 0.4 1 0.2 0.4 0.4 0.4 0.4 Carbon Black 1# 0.002 0.008 0.001 0.002 0.002 0.002 0.002 Other Additives 1# 0.5 1 / 0.5 0.5 0.5 0.5 Other Additives 2# 0.5 1 / 0.5 0.5 0.5 0.5 Other Additives 3# 0.5 1 / 0.5 0.5 0.5 0.5

[0077] Table 2 Formulations of Examples 8 to 14

[0078]

[0079]

[0080] Comparative Examples 1 to 5

[0081] Comparative Examples 1 to 5 provide a series of white polycarbonate compositions, and the weight parts of each component in the formula are shown in Table 3.

[0082] Table 3 Formulations of Comparative Examples 1 to 5

[0083] Comparative Example 1 2 3 4 5 Polycarbonate 1# 89 89 89 89 89 Titanium Dioxide 1# 5 5 5 5 / Titanium Dioxide 4# / / / / 5 Copper Hydroxide 1# / 2 / / 0.4 Copper Hydroxide 5# / / 0.4 / / Nickel Hydroxide / / / 0.4 / Carbon Black 1# 0.002 0.002 0.002 0.002 0.002 Other Additives 1# 0.5 0.5 0.5 0.5 0.5 Other Additives 2# 0.5 0.5 0.5 0.5 0.5 Other Additives 3# 0.5 0.5 0.5 0.5 0.5

[0084] The performance test results of the white polycarbonate compositions of each example and comparative example according to the method mentioned above are shown in Table 4.

[0085] Table 4 Performance Test Results of White Polycarbonate Compositions of Each Example and Comparative Example

[0086]

[0087]

[0088] As can be seen from Tables 1 to 4, the whiteness of the white polycarbonate compositions of the present invention is all above 94, the laser welding strength is all ≥28 MPa, and the reflectance is below 19%. This indicates that the white polycarbonate compositions of the present invention are white, have good laser welding strength and low reflectance.

[0089] In Comparative Example 1, nano-linear copper hydroxide was not added, and the laser welding strength of the white polycarbonate composition decreased significantly; in Comparative Example 2, too much nano-linear copper hydroxide was added, and the whiteness of the white polycarbonate composition was lower than that of Example 1, and the laser welding strength was low; in Comparative Example 3, nano-linear copper hydroxide was replaced with nano-particle copper hydroxide, and the laser welding strength of the white polycarbonate composition was low; in Comparative Example 4, nano-linear copper hydroxide was replaced with nano-linear nickel hydroxide, and the laser welding strength of the white polycarbonate composition was low; in Comparative Example 5, the titanium dioxide of the present invention was replaced with titanium dioxide having a larger particle size, and the white polycarbonate composition not only had low laser welding strength but also had a large reflectance.

[0090] Obviously, the above embodiments of the present invention are merely examples for clearly explaining the present invention, rather than limitations on the implementation manners of the present invention. For those of ordinary skill in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation manners here. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the claims of the present invention.

Claims

1. A white polycarbonate composition, characterized in that The invention comprises the following components in parts by weight: 75-97 parts of polycarbonate, 3-8 parts of titanium dioxide, and 0.1-1 part of copper hydroxide; The average particle size of the titanium dioxide is ≤100nm; The copper hydroxide is in nanowire shape.

2. The white polycarbonate composition according to claim 1, characterized in that: The viscosity average molecular weight of the polycarbonate is 20,000 to 30,000.

3. The white polycarbonate composition according to claim 1, characterized in that: The copper hydroxide has an average diameter of 4 to 80 nm and an average length of 150 to 1200 nm.

4. The white polycarbonate composition according to claim 1, characterized in that: The white polycarbonate composition further comprises the following components in parts by weight: 0.001 to 0.008 parts of carbon black.

5. The white polycarbonate composition according to claim 4, characterized in that: The average particle size of the carbon black is 34 to 55 nm.

6. The white polycarbonate composition according to claim 1, characterized in that: The white polycarbonate composition further comprises the following components in parts by weight: 0.3 to 3 parts of other auxiliary agents.

7. The white polycarbonate composition according to claim 6, characterized in that: The other auxiliary agent is at least one of an antioxidant, a lubricant or an anti-UV agent.

8. The method for preparing the white polycarbonate composition according to any one of claims 1 to 7, comprising the following steps: The components are weighed and mixed according to the formula, melt-extruded and granulated to obtain the white polycarbonate composition.

9. Use of the white polycarbonate composition according to any one of claims 1 to 7 in the preparation of white product parts.

10. The use according to claim 9, characterized in that: The white product component is a laser-welded light-absorbing piece.

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