Nano carbon composite resin ultrathin loudspeaker diaphragm and preparation method thereof

Abstract

The invention provides a nano carbon composite resin ultrathin loudspeaker diaphragm and a preparation method thereof, the thickness of the nano carbon composite resin ultrathin loudspeaker diaphragm is 0.1-0.4 mm, preferably 0.06-0.35 mm, and the nano carbon composite resin ultrathin loudspeaker diaphragm is prepared by adopting a high-speed injection molding mode. According to the nano carbon composite resin ultrathin loudspeaker diaphragm, the formula is optimized, the carbon nanotubes and the graphene are compounded to form a nano reinforced phase, and the application requirements for preparing the loudspeaker diaphragm with the sound velocity being larger than or equal to 5900 m / s and the loss factor being larger than or equal to 0.33 can be met. The high-speed injection molding preparation method effectively overcomes the defect of stable mass production of thin-walled parts below 0.4 mm in the prior art, and has important practical application value.

Description

Technical Field

[0001] This application relates to the technical field of electro-acoustic conversion devices, and particularly relates to an ultra-thin diaphragm material for speakers and its preparation process. The diaphragm material is particularly suitable for the preparation of high-performance diaphragms with a thickness of 0.1 - 0.4 mm, preferably 0.06 - 0.35 mm. Background Art

[0002] Traditional metal diaphragms (such as aluminum, titanium, magnesium, etc.) can achieve fast sound conduction due to their high modulus. Taking the aluminum diaphragm as an example, its sound conduction speed can reach about 5100 m / s. However, at the same time, there are deficiencies such as low internal loss (<0.1) and easy generation of splitting vibration; although the paper diaphragms in the prior art can control the loss to nearly 0.3, their sound speed conduction speed can only reach 1000 - 1500 m / s, and there are defects of insufficient rigidity. Therefore, the diaphragms in the prior art cannot balance high sound speed and high damping, and cannot meet the performance requirements for high-quality speakers. Summary of the Invention

[0003] An object of the present invention is to provide an ultra-thin speaker diaphragm of nano-carbon composite resin that can balance the performance requirements of high sound speed and high damping, so as to solve the problem that the prior art cannot meet the performance requirements for high-quality speakers.

[0004] Another object of the present invention is to provide a preparation method for the above-mentioned ultra-thin speaker diaphragm of nano-carbon composite resin. Through a high-speed injection molding process, the stable mass production of the ultra-thin speaker diaphragm of nano-carbon composite resin is ensured.

[0005] For the ultra-thin speaker diaphragm of nano-carbon composite resin according to the first aspect embodiment of the present invention, the raw materials for preparing the diaphragm include the following components in the following mass percentages (wt%):

[0006] Nano-reinforcing phase 5 - 15

[0007] Dispersant 3.5 - 7

[0008] Damping modifier 8 - 12

[0009] The balance is matrix resin and inevitable impurities.

[0010] According to some embodiments of the present invention, the matrix resin is a high-flow engineering plastic, preferably one or a combination of PC, PA6, and PEEK; the matrix resin has a melt index ≥ 30 g / 10 min at a temperature of 230°C and a load of 2.16 kg.

[0011] According to some embodiments of the present invention, the nano-reinforcing phase is obtained by compounding carbon nanotubes (CNT) and graphene.

[0012] According to some embodiments of the present invention, the dispersant is obtained by compounding a silane coupling agent and an ionomer compatibilizer. Preferably, the addition amount of the silane coupling agent accounts for 0.5-2% by weight (wt%) of the raw materials for preparing the nano-carbon composite resin ultra-thin speaker diaphragm, and the addition amount of the ionomer compatibilizer accounts for 3-5% by weight (wt%) of the raw materials for preparing the nano-carbon composite resin ultra-thin speaker diaphragm; the ionomer compatibilizer can be selected from one or a combination of several of Surlyn, POE ionomer, and Fischer-Tropsch wax ionomer.

[0013] According to some embodiments of the present invention, the damping modifier is hydrogenated nitrile rubber particles, and the particle size of the hydrogenated nitrile rubber particles is 50-200 nm.

[0014] The method for preparing a nano-carbon composite resin ultra-thin speaker diaphragm according to the second aspect embodiment of the present invention includes the following steps:

[0015] (1) Pre-dispersion: The nano-enhancing phase and the dispersant are melt-blended in a twin-screw extruder to obtain a premix.

[0016] (2) High-speed injection molding: After the premix, the damping modifier and the matrix resin are stirred evenly, and then sent to an injection molding machine for high-speed injection molding to obtain a semi-finished diaphragm. The parameters of the high-speed injection molding include:

[0017] The injection speed ≥ 800 mm / s, the holding pressure 80-120 MPa; the mold temperature 120-150 °C, and the melt temperature is controlled within a range 10-20 °C lower than the melting point of the matrix resin; the foaming rate is controlled ≤ 3%.

[0018] (3) Surface modification: Radial grooves are formed on the surface of the semi-finished diaphragm obtained in the second step by laser etching or mold transfer to enhance the radial stiffness.

[0019] According to some embodiments of the present invention, the pre-dispersion controls the temperature of the melt-blending to be 200-240 °C and the rotation speed to be 300-500 rpm.

[0020] According to some embodiments of the present invention, the thickness gradient distribution of the semi-finished diaphragm is: 0.25 ± 0.05 mm in the central region, and gradually thins to 0.1 mm at the edge, so as to reduce the splitting vibration.

[0021] According to some embodiments of the present invention, in the surface modification process, the width of the radial grooves is controlled to be 5-20 μm.

[0022] The sound velocity of the nano-carbon composite resin ultra-thin speaker diaphragm described in the present invention is ≥5900 m / s, and the loss factor at room temperature is ≥0.33, which can simultaneously meet the performance requirements of high sound velocity and high damping; the preparation method of the nano-carbon composite resin ultra-thin speaker diaphragm ensures the stable mass production of the nano-carbon composite resin ultra-thin speaker diaphragm through a high-speed injection molding process. Through the collaborative innovation of materials - processes - structures, the present invention breaks through the performance boundaries of traditional materials and achieves good technical effects. Detailed Embodiments

[0023] The principles and features of the present invention are described below. The examples given are only for explaining the present invention and are not intended to limit the scope of the present invention. The present invention will be described more specifically by way of example in the following paragraphs. The advantages and features of the present invention will be clearer according to the following description and claims.

[0024] It should be noted that unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which the present invention belongs. The terms used in the description of the present invention herein are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more of the related listed items.

[0025] Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts are within the scope of protection of the present application.

[0026] Example 1

[0027] The nano-carbon composite resin ultra-thin speaker diaphragm uses PA6 as the matrix resin, and is compounded with a nano-enhanced phase (10 wt%) of carbon nanotubes (CNT) and graphene (the mass ratio of CNT / graphene = 3:1), a dispersant (4 wt%) compounded with a silane coupling agent (1 wt%) and an ionomer compatibilizer (Surlyn), and 11 wt% of hydrogenated nitrile rubber particles as a damping modifier (particle size 150 nm) as raw materials.

[0028] The preparation process of the nano-carbon composite resin ultra-thin speaker diaphragm using the above raw materials includes:

[0029] (1) Pre-dispersion: The nano-enhanced phase and the dispersant are melt-blended in a twin-screw extruder to obtain a premix. The pre-dispersion controls the temperature of the melt-blending at 220 °C and the rotation speed at 350 rpm;

[0030] (2) High-speed injection molding: After uniformly stirring the premix, damping modifier, and matrix resin, it is sent to an injection molding machine for high-speed injection molding to obtain a diaphragm semi-finished product. The parameters of the high-speed injection molding include:

[0031] Injection speed ≥ 800 mm / s, holding pressure 80 - 120 MPa; mold temperature 120 - 150 °C, melt temperature controlled within the range 10 - 20 °C lower than the melting point of the matrix resin; control the foaming rate ≤ 3%;

[0032] The thickness gradient distribution of the diaphragm semi-finished product is: 0.25 ± 0.05 mm in the central area, gradually thinning to 0.1 mm at the edge, thereby reducing the splitting vibration;

[0033] (3) Surface modification: Radial grooves are formed on the surface of the diaphragm semi-finished product obtained in step (2) by laser etching or mold transfer to enhance the radial stiffness, and the width of the radial grooves is controlled to be 13 μm.

[0034] Test conditions:

[0035] Sound velocity test: 5920 ± 50 m / s (laser Doppler vibrometer, 20 kHz);

[0036] Loss factor: 0.33 (dynamic mechanical analyzer DMA, 1 kHz);

[0037] Molding qualification rate: 98.7% (0.2 mm thickness, Toshiba EC-160S injection machine).

[0038] Aging test: Place the bonded substrate in an aging environment (temperature: 85 °C, humidity: 85%) for 1000 hours, then cool it to room temperature and test its bonding strength.

[0039] Compare the above examples with Comparative Example 1 (pure PA6 diaphragm) and Comparative Example 2 (pure aluminum foil). The relevant results are as follows:

[0040] Sound velocity (m / s) Loss factor Minimum formable thickness (mm) Comparative Example 1 2100 0.12 0.5 Comparative Example 2 5100 0.08 0.3 (stamping) Example 1 5920 0.33 0.1 (injection)

[0041] As can be seen from the test results in the table, the nano-carbon composite resin ultra-thin speaker diaphragm and its new preparation method provided by the embodiments of the present invention achieve good technical effects by means of the synergistic innovation of materials - processes - structures, namely "nano-phase compounding and synergistic enhancement" (i.e., CNT provides an axial sound conduction path, graphene enhances the in-plane stiffness, especially when the ratio of the two is 3:1, the sound speed increases by 35% without sacrificing toughness), "shear-induced orientation" (forming a radial arrangement of nano-fillers in the mold cavity through high-speed injection at >800 mm / s to reduce the transverse acoustic impedance), and "micro-foaming synergistic shape control" (0.5 - 1.5% closed-cell structure compensates for the shrinkage of thin-walled parts, and the thickness tolerance ≤ ±3 μm). The obtained nano-carbon composite resin ultra-thin speaker diaphragm has broad application prospects and important research value, breaking through the performance boundaries of traditional materials.

[0042] The present invention illustrates a nano-carbon composite resin ultra-thin speaker diaphragm and its preparation method through the above embodiments, but the present invention is not limited to the above embodiments, that is, it does not mean that the present invention must rely on the above embodiments to be implemented. Those skilled in the art should understand that any improvement to the present invention, the equivalent substitution of each raw material of the product of the present invention, the addition of auxiliary components, the selection of specific methods, etc., all fall within the protection scope of the present invention.

Claims

1. A nano-carbon composite resin ultra-thin speaker diaphragm, characterized in that, The raw materials for preparing the nano-carbon composite resin ultra-thin speaker diaphragm include the following components in the following mass percentages (wt%): Nano-reinforcing phase 5 - 15 Dispersant 3.5 - 7 Damping modifier 8 - 12 The balance is matrix resin and inevitable impurities.

2. The ultra-thin speaker diaphragm made of nano-carbon composite resin according to claim 1, wherein The matrix resin is a high-flow engineering plastic, preferably a combination of one or more of PC, PA6, and PEEK; the matrix resin has a melt index ≥ 30 g / 10 min at a temperature of 230 °C and a load of 2.16 kg.

3. The nano-carbon composite resin ultra-thin speaker diaphragm according to claim 1, wherein The nano-reinforcing phase can be obtained by compounding carbon nanotubes and graphene. Preferably, the compounding ratio range (mass ratio) of carbon nanotubes to graphene is 1 - 4:

1.

4. The nano-carbon composite resin ultra-thin speaker diaphragm according to claim 1, wherein The dispersant can be obtained by compounding a silane coupling agent and an ionomer compatibilizer. Preferably, the addition amount of the silane coupling agent accounts for 0.5 - 2 wt% of the raw materials for preparing the nano-carbon composite resin ultra-thin speaker diaphragm, and the addition amount of the ionomer compatibilizer accounts for 3 - 5 wt% of the raw materials for preparing the nano-carbon composite resin ultra-thin speaker diaphragm; the ionomer compatibilizer can be selected from a combination of one or more of Surlyn, POE ionomer, and Fischer-Tropsch wax ionomer.

5. The nano-carbon composite resin ultra-thin speaker diaphragm according to claim 1, characterized in that, The damping modifier can be hydrogenated nitrile rubber particles, and the particle size of the hydrogenated nitrile rubber particles is 50 - 200 nm.

6. The nano-carbon composite resin ultra-thin speaker diaphragm according to claim 1, characterized in that, The sound velocity of the nano-carbon composite resin ultra-thin speaker diaphragm is ≥ 5900 m / s, and the loss factor at room temperature is ≥ 0.

33.

7. A preparation method of a nano-carbon composite resin ultra-thin speaker diaphragm, which is applied to a nano-carbon composite resin ultra-thin speaker diaphragm according to any one of claims 1 to 6, characterized in that, The preparation method includes the following steps: (1) Pre-dispersion: Melting and blending the nano-reinforcing phase and the dispersant in a twin-screw extruder to obtain a premix; (2) High-speed injection molding: After uniformly stirring the premix, the damping modifier, and the matrix resin, send them to an injection molding machine for high-speed injection molding to obtain a semi-finished diaphragm. The parameters of the high-speed injection molding include: Injection speed ≥ 800 mm / s, holding pressure 80 - 120 MPa; mold temperature 120 - 150 °C, melt temperature controlled within a range 10 - 20 °C lower than the melting point of the matrix resin; in-mold micro-foaming control, controlling the foaming rate ≤ 3% to reduce shrinkage deformation; (3) Surface modification: Forming radial grooves on the surface of the semi-finished diaphragm obtained in step (2) by laser etching or mold transfer to enhance the radial stiffness.

8. The preparation method of the nano-carbon composite resin ultra-thin speaker diaphragm according to claim 7, characterized in that, The pre-dispersion controls the temperature of the melting and blending to be 200 - 240 °C and the rotation speed to be 300 - 500 rpm.

9. The method for preparing a nano-carbon composite resin ultra-thin speaker diaphragm according to claim 7, characterized in that The thickness gradient distribution of the semi-finished diaphragm is: 0.25 ± 0.05 mm in the central region, gradually thinning to 0.1 mm at the edge, thereby reducing the splitting vibration.

10. The method for preparing a nano-carbon composite resin ultra-thin speaker diaphragm according to claim 7, wherein In the surface modification process, control the width of the radial grooves to be 5 - 20 μm.