JPH02276399A - Production of speaker diaphragm - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a speaker diaphragm.

[Prior Art] The diaphragm of a speaker is also called a diaphragm among the parts that make up the speaker, and in order to expand the piston movement range in terms of performance, the diaphragm has a specific elasticity *E/D (E: elastic modulus,
D=density) should be as large as possible, and it should have an appropriate internal loss in order to smooth the frequency characteristics in the high frequency range.

Conventionally, in order to increase E/D, a method has been used in which carbon fibers are mixed into a diaphragm mainly made of paper pulp. In addition, in recent years, plastic materials such as carbon fiber (Japanese Patent Application No. 62-202699) and mica (Japanese Patent Application No. 57-1
95976) etc. have been mixed to improve E/D. On the other hand, in order to increase the internal loss, methods have been used in which the diaphragm is coated with or impregnated with various organic paints.

[Issue g to be solved by the invention] In the method of mixing carbon fiber into paper pulp as described above,
There is a limit to the amount of carbon fiber that can be mixed in, so it cannot be expected to increase E/D much, and methods that mix carbon fiber, mica, etc. into plastic materials increase the melt viscosity of the material, resulting in molding constraints. In addition, in the method of impregnating the diaphragm with an organic paint, there are problems such as an increase in internal loss and a decrease in E/D. There are other attempts to obtain a diaphragm with high E/D and appropriate internal loss, but it is impossible to satisfy the characteristics and production requirements regarding both E/D and internal loss. There was a section called.

This invention was made in order to solve this problem, and aims to provide a method for manufacturing a speaker diaphragm that has an E/D as high as possible and a moderate internal loss. be.

[Means for Solving the Problems] A method for manufacturing a speaker diaphragm of the present invention includes 20 to 75% by weight of a thermoplastic liquid crystal polymer, 20 to 50% by weight of poly(4-methylpentene-1), and fibrous and A material containing 5 to 30% by weight of flaky filler is injection molded.

[Operation] During injection molding, the melt of the thermoplastic liquid crystal polymer and poly(4-methylpentene 1) cools and solidifies in the mold while being oriented with the fibrous or flaky filler. The specific elastic modulus of the diaphragm improves, and internal loss becomes moderately high.

[Example] It is well known that when a polymer is oriented, its modulus of elasticity and tensile strength are improved. Furthermore, it is known that polymer orientation occurs during melt molding of thermoplastic resins. However, in molding using conventional materials, the orientation of the polymer is small and the improvement in elastic modulus is small, and it has not been possible to obtain a material that satisfies the elastic modulus required for a speaker diaphragm.

On the other hand, it is well known that thermotropic liquid crystal polymers that exhibit a nematic phase when melted melt when heat is applied, lowering their viscosity and exhibiting excellent fluidity. It is also well known that the melt viscosity of poly(4-methylpentene 1) decreases rapidly as shear stress increases. This mixed melt of liquid crystal polymer and poly(4 methylpentene 1) is adjusted to a temperature lower than the solidification temperature of the liquid crystal polymer or poly(4 methylpentene 1) to form a mold with a small thickness such as a speaker diaphragm. When the liquid crystal polymer is filled in the liquid crystal polymer, the liquid crystal polymer cools and solidifies while being oriented together with poly(4 methylpentene 1). The orientation of the resulting diaphragm molded product is highly dependent on the melt flow rate and mold temperature. Furthermore, since the orientation of the center of the plate B depends on the shear rate and shear stress, it increases as the melt flow rate increases and as the thickness of the molded article decreases. Note that by using the liquid crystal polymer and poly(4-methylpentene 1) together, the viscosity of the poly(4-methylpentene 1) decreases even when shear stress increases, so that stable molding can be performed. In addition, the fibrous and flaky fillers are oriented together with the resin within the range shown in the present invention, and have the effect of stabilizing the flow of the resin. The effect of changing the anisotropy of the elastic modulus of the diaphragm by orienting it in a direction different from that of the diaphragm is shown.

FIG. 1 is a perspective view showing a state in which a speaker diaphragm according to an embodiment of the present invention is molded and manufactured, in which (1) is an injection part and (2) is a molding part. That is, by injecting the resin from the center of the diaphragm, the flow of the resin becomes a diffusion flow, and the molded product, which is largely oriented in the A direction and has a component in the B direction shown in FIG. I can do something. In addition, in this invention, since fibrous and flaky fillers are mixed into the resin, the tree+11 and the filler have a complementary effect on the orientation, and the orientation of the diaphragm, which is a molded product, can be greatly improved. The speaker diaphragm obtained in the example of the present invention, which exhibits the effect of increasing the elasticity, has an excellent specific elastic modulus E/D compared to a diaphragm in which no filler is mixed.

Liquid crystal polymers according to the present invention include thermotropic liquid crystal polymers, such as copolymers of polyethylene terephthalate and para-hydroxybenzoic acid, copolymers of polyethylene terephthalate and para-acetoxybenzoic acid, copolymers of para-acetoxybenzoic acid, and para-acetoxybenzoic acid. , ω, aromatic acid, a copolymer of terephthalic acid and naphthalene diacetate, a polyester consisting of terephthalic acid, paraoxybenzoic acid, and P,I''-biphenol, and other known or commercially available liquid crystal polymers exhibiting thermotropism. In addition, this thermoplastic liquid crystal polymer must be contained in an amount of 20 to 75% by weight; if it exceeds 75%, the effect of the present invention cannot be obtained, and if it is less than 20%, the content of the liquid crystal polymer The fruits and vegetables of this invention cannot be obtained due to insufficient orientation.

The poly(4-methylpentene 1) according to this invention may be any known or commercially available polymer, and the poly(4-methylpentene 1) may have a 20 to 50 i
Rffi% must be contained, and if it exceeds 50% or less than 20%, the effects of this invention cannot be obtained.

Note that the effects of the present invention can be obtained even if other thermoplastic resins 1ff+ are mixed and used. Thermoplastic resins that can be used here include polyethylene, polypropylene,
There are no particular limitations on the thermoplastic resin as long as it is a known thermoplastic resin such as polyethylene propylene copolymer, polyethylene terephthalate, polybutylene terephthalate, polystyrene, polysulfone, polyphenylene sulfide, polyimide, polyamide, polycarbonate, polyether sulfone, and the like.

The fibrous and flaky fillers used in this invention may be those commonly used in resins, such as glass fiber, carbon fiber, wollastonite, talc, mica, glass foil, various whiskers, and graphite. The blending amount of this fibrous filler is preferably 5 to 30% based on heavy cellulose, and if it is less than 55%, the effect of the present invention cannot be obtained, and if it exceeds 30%, the resin Fluidity decreases, and the desired effect of the present invention cannot be obtained.

In the present invention, various additives such as a stabilizer against heat or light, a coupling agent with a filler, or an internal mold release agent may be added as necessary.

The mold that can be used in this invention is not limited to any known mold that is generally used for molding thermoplastic resins, and methods for injecting resin into the mold include An injection molding method is used which allows for good speed control. In addition to the injection molding method of this invention, there are compression molding methods, transfer molding methods, extrusion molding methods, etc. as molding methods for melting and molding resin, but in these molding methods, the speed of the flow of the molten resin is controlled. It is difficult to control and the effects of this invention cannot be obtained.

EXAMPLES The present invention will be explained in detail below using examples.

Example 1 Polyester-based liquid crystal polymer resin (trade name Tubaculate E: 121 manufactured by E-Ryo Kasei Co., Ltd.) 50% by weight, poly(4 methylpentene 1) FA resin (trade name TPX-DX8)
10 (Mitsui Petrochemical Co., Ltd.) 20% by weight) + 1:30 tons of chopped carbon fiber strands with a uniform length of 61 and an outer diameter of 8 μm were added, thoroughly mixed in a tumbler, and a screw with a diameter of 30 mm was added. The mixture was kneaded at 270°C using an extruder to form pellets. The molded product has an outer diameter of 125 mm, an inner diameter of 30 mm, and a thickness of 0.4 mm.The pellet is placed in a metal mold into which polymer can be injected from the center of the inner diameter part, and then the resin is molded using a 5-ton injection molding machine with a mold cuff. Temperature 320℃
, injection pressure 160 HPa, injection time 5 seconds, mold temperature 90
It was molded at a temperature of 30 seconds. E/D and ta determined by the vibration lead method for a test piece cut from a molded product
A1α of nδ (loss tangent) is shown in the table. Similarly, a speaker diaphragm according to an embodiment of the present invention was cut out from a molded product, and its sound pressure-frequency characteristics were determined. Figure 2 shows the sound pressure (d
B) - Frequency (Ilz) characteristic diagram, in which (A) shows the characteristics of the speaker diaphragm according to an embodiment of the present invention in Example 1. In FIG. 2, the vertical axis is the response (Ilz) expressed in decibels. dB), and the horizontal axis is the frequency in Hertz (II z ).Also, the cross section of the above diaphragm is enlarged with a microscope and is 1NS!
As it turns out, the surface layer 9 is a smooth surface with highly oriented liquid crystal polymer and carbon fibers, and the center part has highly oriented carbon fibers and also oriented liquid crystal polymer.

Example 2 Polyester-based liquid crystal polymer resin (trade name Tubaculate E321 manufactured by Mitsubishi Kasei Corporation) 75.R+1 (%, poly(4 methylpentene 1) resin (trade name Tl) X-DX
810 Mitsui Petrochemical Co., Ltd.! After adding 5 F: 11j% of chopped carbon fiber strands of 1p, average length 6mm and outer diameter 8μm to >20% heavy debt, thoroughly mixed in a tumbler and extruded using an extruder with a screw diameter of 10mm. 270℃
The mixture was kneaded to make pellets. The molded product has an outer diameter of 125 mm, an inner diameter of 30 mm, and a thickness of 0.4 mm.The formed pellet is placed in a metal mold that can be filled with polymer from the center of the inner diameter using an injection molding machine with a mold clamping cuff of 5 mm. Molding was performed at a resin temperature of 320° C., an injection pressure of 1408 Pa, an injection time of 5 seconds, a mold temperature of 90° C., and a cooling time of 30 seconds. The values of E/D and an δ (loss tangent) determined by the vibration lead method for test pieces cut from the molded products are shown in the table. Similarly, a speaker diaphragm was cut out from a molded product, and its ff and pressure-frequency characteristics were determined, as shown in (B) in Figure 2.
In addition, when we observed the two sides of the diaphragm under magnification using a microscope, we found that the two sides of the diaphragm had a smooth surface with highly oriented liquid crystal polymer and carbon fibers, and the center part had highly oriented carbon fibers and liquid crystal polymer as well. Oriented.

Example 3 20% by weight of polyester-based liquid crystal polymer resin (trade name: Tubaculate 321 manufactured by Mitsubishi Chemical Corporation), poly(4
Methylpentene 1) Resin (product name TPX-DX810 manufactured by Mitsui Petrochemicals Co., Ltd.) 50% by weight with ilZ average length 6mm
After adding 30 weight 1% carbon fiber chopped strands having an outer diameter of 8 μm, they were mixed on top using a tumbler and kneaded at 270° C. using an extruder with a screw diameter of 30 mm to form pellets. Outer diameter 125mm, inner diameter 30mm, thickness 0.4mm
The formed pellet is placed in a metal mold that allows the polymer to be deposited from the center of the inner diameter part, and then the pellet is clamped with a mold cuff of 5 tons.
On injection molding machine was used at a resin temperature of 320° C., an injection pressure of 180 MPa, an injection time of 5 seconds, a mold temperature of 90° C., and a cooling time of 30 seconds. The values of E/D and tan δ (loss tangent) determined by the vibration lead method for test pieces cut from the molded products are shown in the table. Similarly, a speaker diaphragm was cut out from a molded product and its sound pressure-frequency characteristics were determined, as shown in (C) in Figure 2. In addition, the new surface of the diaphragm was observed under a microscope under magnification. The surface layer 4 is a smooth surface in which liquid crystal polymer and carbon fibers are highly oriented, and in the center, carbon fibers are highly oriented and liquid crystal polymer is also oriented.

Example 4 60% by weight of polyester-based liquid crystal polymer resin (trade name: Tubaculate 321 manufactured by Mitsubishi Chemical Corporation), poly(4
Methylpentene 1) Resin (trade name TPX-DX810 Mitsui Petrochemicals Co., Ltd. Ha) 20% by weight of carbon fiber chopped strands with an average length of 6mm and an outer diameter of 8μm are added by weight of 10
%, mix thoroughly with a tumbler and screw diameter 3.
The mixture was kneaded at 270° C. using a 0 mm extruder to form pellets. The molded product has an outer diameter of 125 mm, an inner diameter of 30 mm, and a thickness of 0.4 mm. Polypropylene resin (product name: After adding XK7050 Chisso Co., Ltd. pellets and mixing well, using an injection molding machine with a mold clamping cuff of 5LOn, the resin temperature was 320°C, the injection pressure was 180MPa, the injection time was 5 seconds, the mold temperature was 90°C,
It was molded with a cooling time of 30 seconds. E/D and tanδ determined by the vibrating lead method for a test piece cut from a molded product
The values of (loss tangent) are shown in the table. Similarly, a speaker diaphragm was cut out from a molded product and its sound pressure-frequency characteristics were determined, as shown in (D) in FIG.

As is clear from the table and FIG. 2, in the diaphragm according to the embodiment of the present invention, the liquid crystal polymer, poly(4 methylpentene 1), and fibrous or flaky filler are oriented in the mold during injection molding. Because of this structure, the surface layer in the thickness direction is strongly oriented in the resin flow direction, and the center part in the thickness direction is oriented in a direction different from the flow direction, resulting in a sand inch structure, which has a high elastic modulus and moderate internal loss. , it can be seen that this is a diaphragm with little distortion and stretch in the high range. In addition, in the above example,
Although the embodiment is limited to a diaphragm, it goes without saying that similar effects can be obtained even when applied to a center cap of a speaker, etc.

[Effects of the Invention] As explained above, the present invention is based on 20 to 75% by weight of a thermoplastic liquid crystal polymer, 20% by weight of poly(4 methylpentene)
~50% by weight of fibrous and flaky fillers 4 times 5
By injection molding a material containing up to 30% by weight, a method for manufacturing a speaker diaphragm with high E/D and internal loss can be obtained.

[Brief explanation of drawings]

FIG. 1 is a perspective view showing a resin flowing part of a mold when manufacturing a speaker diaphragm according to an embodiment of the present invention, and FIG. 2 is a perspective view showing the sound of a speaker diaphragm according to an embodiment of the present invention. It is a pressure (dB)-frequency (llz) characteristic diagram. In the figure, (1) is the injection part, and (2) is the molding part.

Claims (1)

[Claims] A speaker diaphragm injection-molded containing 20-75% by weight of a thermoplastic liquid crystal polymer, 20-50% by weight of poly(4-methylpentene), and 5-30% by weight of fibrous and flaky fillers. Production method.