Laser-engraved liquid crystal polymer composition and preparation method thereof
Technical Field
The invention relates to the technical field of liquid crystal polymers, in particular to a laser-engraved liquid crystal polymer composition and a preparation method thereof.
Background
After apple launches the full-screen mobile phone iPhone X, domestic mobile phone manufacturers such as Huashi, millet, VIVO, OPPO and the like immediately follow the iPhone X, and independent full-screen mobile phones are launched in a dispute. The screen occupancy rate soared from 80% to 93.8% (official announcement). The screen occupation ratio is larger and larger, and the loading space for the antenna is smaller and smaller. From a 16:9 screen to an 18:9 or even larger scale screen, the space left for the antenna is roughly only 3-5 mm or less. The position that can put the antenna is more restricted, and the headroom district of antenna reduces, and the antenna is nearer with metal structure spare, and this makes the omnidirectional communication performance of antenna very poor, also makes the design degree of difficulty of antenna promote.
At present, the soft board substrate which is applied more is mainly Polyimide (PI), but because the PI substrate has large dielectric constant and loss factor, large moisture absorption and poor reliability, the PI soft board has serious high-frequency transmission loss and poor structural characteristics, and cannot adapt to the current high-frequency high-speed trend.
In engineering plastics, LCP has the following excellent properties suitable for making antennas: (1) excellent dielectric properties: the relative permittivity is constant and the dielectric loss tangent is small in the adopted frequency area; (2) good physical properties: including dimensional stability, heat resistance, flame retardancy, stiffness, and the like; (3) good mold flow: can be processed into small-sized or thin-part molded articles.
However, the liquid crystal polymer as an antenna still has problems of poor processability and low yield.
Disclosure of Invention
In order to overcome the defects and shortcomings in the prior art, the invention aims to provide a laser engraving liquid crystal polymer composition and a preparation method thereof.
The purpose of the invention is realized by the following technical scheme:
a laser engraving liquid crystal polymer composition comprises the following raw materials in parts by weight:
according to the invention, a large amount of filler is added into LCP for blending modification, so that the mechanical property and dielectric property of the composition can be improved, and a small amount of lubricant is added to ensure that the composition has good molding processability; in addition, the proper amount of the laser etching auxiliary agent is added into the composition, so that the laser etching effect of the composition is improved, the composition has excellent processability, and the yield of the manufactured antenna is improved.
Wherein the filler is at least one of mesoporous silica, calcium carbonate, nano-cellulose and glass fiber.
Generally, the inorganic fillers used in plastics are based on calcium carbonate and glass fibers, and especially for LCP, the addition of glass fibers can greatly improve the warpage resistance. However, the composition of the glass fiber is complex, the performance difference of the glass fibers of different types is large, the dielectric constant of the common glass fiber is about 6.5, and the dielectric loss is easily increased when the common glass fiber is added into the composition. Therefore, in the present invention, one of the fillers used is mesoporous silica. The mesoporous silica is a rigid particle with porosity, and air contained in the mesoporous silica is a medium with low dielectric loss, so that the mesoporous silica can effectively improve the mechanical property and the node property of the PCL material. However, as a material for manufacturing the antenna substrate, flexibility and warpage prevention of the PCL material are very important. Therefore, the nano-cellulose is selected and adopted in the re-filling material, and the length-diameter ratio of the nano-cellulose can effectively improve the toughness of the PCL material. In addition, the mesoporous silica and the nanocellulose are subjected to ultrasonic dispersion, and the nanocellulose can be entangled with holes on the surface of the mesoporous silica, so that a divergent extending 'antenna' is formed in the mesoporous silica, and the dispersibility of the filler can be obviously improved, and the mechanical property of the LCP material can be improved.
Preferably, the filler of the invention is composed of mesoporous silica and nanocellulose according to the mass ratio of 1:4-6, the particle size of the mesoporous silica is 200-300nm, and the specific surface area is 450-550m2Per g, pore volume of 0.4-0.6cm2(ii)/g; the nano-cellulose has the particle size distribution D50 of 15-20nm and the length-diameter ratio of 500-600, and can be obtained by hydrolyzing sisal fibers in 65 wt% sulfuric acid. The inventionThe dispersion method of the mesoporous silicon dioxide and the nano-cellulose comprises the following steps: mixing mesoporous silicon dioxide, nano-cellulose and deionized water according to a mass ratio of 1: mixing at a ratio of 4-6:500, performing ultrasonic dispersion at 20-40kHz for 20-30min, then performing centrifugal washing and freeze drying to obtain the filler.
The laser etching auxiliary agent is a metal complex auxiliary agent, and is further preferably basic copper phosphate, for example, MEGA-CHP100 can be specifically adopted, the quality performance is stable, the composition disclosed by the invention is directly subjected to laser on a mobile phone shell through LDS to form an antenna, the internal mobile phone metal interference is avoided, and the mobile phone volume is effectively reduced.
Wherein the antioxidant is at least one of antioxidant 1010 and antioxidant 168. Preferably, the antioxidant 1010 and the antioxidant 168 are mixed in a weight ratio of 1:1, so that the oxidation resistance of the composition is effectively improved.
Wherein the lubricant is at least one of talcum powder, calcium stearate, zinc stearate and polyethylene wax. Preferably, the lubricant is talc, which improves the mold release properties of the composition.
Wherein the LCP is composed of 60-80 mol% of a primary repeating unit and 20-40 mol% of a secondary repeating unit, the primary repeating unit is a repeating unit of 6-hydroxy-2-naphthoic acid and/or a repeating unit of p-hydroxybenzoic acid, and the secondary repeating unit is a repeating unit of terephthalic acid and a repeating unit of hydroquinone. The LCP provided by the invention has low dielectric constant and excellent mechanical property.
Wherein the main repeating units are a repeating unit of 6-hydroxy-2-naphthoic acid and a repeating unit of p-hydroxybenzoic acid, and the molar ratio of the repeating unit of 6-hydroxy-2-naphthoic acid to the repeating unit of p-hydroxybenzoic acid is 60-80: 20-40. The main repeating units employed in the present invention allow LCP's to exhibit good impact strength and molding processability.
Wherein, in the secondary repeating units, the molar ratio of the repeating unit of the terephthalic acid to the repeating unit of the hydroquinone is 0.9-1.1: 1. The secondary repeating units employed in the present invention allow the LCP to exhibit relatively stable heat resistance and physical properties.
The preparation method of the laser engraved liquid crystal polymer composition comprises the following steps: mixing the raw materials, and then putting the mixture into a double-screw extruder to perform melt extrusion granulation to obtain the laser engraved liquid crystal polymer composition.
The invention has the beneficial effects that: according to the invention, a large amount of filler is added into LCP for blending modification, so that the mechanical property and dielectric property of the composition can be improved, and a small amount of lubricant is added to ensure that the composition has good molding processability; in addition, the proper amount of the laser etching auxiliary agent is added into the composition, so that the laser etching effect of the composition is improved, the composition has excellent processability, and the yield of the manufactured antenna is improved.
Detailed Description
The present invention will be further described with reference to the following examples for facilitating understanding of those skilled in the art, and the description of the embodiments is not intended to limit the present invention.
Example 1
A laser engraving liquid crystal polymer composition comprises the following raw materials in parts by weight:
wherein the filler is composed of mesoporous silica and nano-cellulose according to the mass ratio of 1:5, the particle size distribution D50 of the mesoporous silica is 246.2nm, and the specific surface area is 500m2Per g, pore volume of 0.5cm2(ii)/g; the nano-cellulose has the particle size distribution D50 of 18.7nm and the length-diameter ratio of 500-600, and can be obtained by hydrolyzing sisal fibers in 65 wt% sulfuric acid. The dispersion method of the mesoporous silicon dioxide and the nano-cellulose comprises the following steps: mixing mesoporous silicon dioxide, nano-cellulose and deionized water according to a mass ratio of 1: mixing at a ratio of 5:500, performing ultrasonic dispersion at 30kHz for 25min, then performing centrifugal washing and freeze drying to obtain the filler.
The laser etching auxiliary agent is a metal complex auxiliary agent.
Wherein the antioxidant consists of an antioxidant 1010 and an antioxidant 168 according to the weight ratio of 1: 1.
Wherein the lubricant consists of calcium stearate and zinc stearate in a weight ratio of 1: 1.
Wherein the LCP is made up of 70 mol% of major repeating units and 30 mol% of minor repeating units.
Wherein the main repeating units are a repeating unit of 6-hydroxy-2-naphthoic acid and a repeating unit of p-hydroxybenzoic acid, and the molar ratio of the repeating unit of 6-hydroxy-2-naphthoic acid to the repeating unit of p-hydroxybenzoic acid is 70: 30.
Wherein, in the secondary repeating units, the molar ratio of the repeating unit of the terephthalic acid to the repeating unit of the hydroquinone is 1: 1.
The preparation method of the laser engraved liquid crystal polymer composition comprises the following steps: mixing the raw materials, and then putting the mixture into a double-screw extruder to perform melt extrusion granulation to obtain the laser engraved liquid crystal polymer composition.
Example 2
The present embodiment is different from embodiment 1 in that:
a laser engraving liquid crystal polymer composition comprises the following raw materials in parts by weight:
example 3
The present embodiment is different from embodiment 1 in that:
a laser engraving liquid crystal polymer composition comprises the following raw materials in parts by weight:
example 4
The present embodiment is different from embodiment 1 in that:
the filler is alkali-free glass fiber.
Example 5
The present embodiment is different from embodiment 1 in that:
the filler is mesoporous silica with equal weight parts.
Example 6
The present embodiment is different from embodiment 1 in that:
the filler is nano cellulose with equal parts by weight.
Example 7
The present embodiment is different from embodiment 1 in that:
the filler is composed of mesoporous silica and nano-cellulose according to the mass ratio of 1:5, but the mesoporous silica and the nano-cellulose are not only subjected to ultrasonic dispersion but also directly fed into a double-screw extruder for melt extrusion granulation.
The compositions of examples 1-6 were tested for flexural strength, impact strength and dielectric constant according to ASTM D-790, ASTM D-256 and ASTM D-150, respectively, and the results are given in the following table:
as can be seen from the above table, the performance difference of examples 1-3 is mainly determined by the amount of the filler, and as the amount of the filler increases, the bending strength and the impact strength are both improved to a certain extent, and the dielectric constant also increases; from the data of example 4, it is known that the mechanical properties of LCP are improved most significantly by glass fiber, but the dielectric constant is also increased rapidly, and the requirement of low dielectric constant is not satisfied; from the test data of examples 5 to 6, it is known that the mesoporous silica has the most significant improvement in dielectric properties and also has better improvement in bending strength than nanocellulose, which is more reflected in improvement in impact properties of the composition; from the test data of example 7, it is understood that if mesoporous silica and nanocellulose are directly fed into a twin-screw extruder for melt extrusion granulation, the performance of the obtained composition is balanced between examples 5 and 6, and no particular improvement is achieved, while example 1 shows a better level of mechanical performance, which means that nanocellulose can be entangled with the pores on the surface of mesoporous silica to form divergent extended "tentacles" on the mesoporous silica, thereby significantly improving the dispersibility of the filler and improving the mechanical performance of the PCL material, while example 1 also shows a certain degree of improvement in dielectric performance compared to example 7, and shows that the dielectric constant is mainly determined by the properties of the raw materials, but also relates to the dispersibility of the filler.
The above-described embodiments are preferred implementations of the present invention, and the present invention may be implemented in other ways without departing from the spirit of the present invention.