JPH02233100A - Material for speaker frame - Google Patents

Abstract

PURPOSE:To make a magnetic characteristic and an appearance excellent, and to raise the rigidity and the specific weight of moldings by mixing thermoplastic or thermosetting synthetic resin and whisker of high modulus of elasticity consisting of zinc oxide whose crystal grew toward different four directions from a center. CONSTITUTION:The whisker is zinc oxide whisker whose molecular formula is ZnO and whose specific weight is 5.7, and is of the shape of what is called a tetrapod whose crystal grew toward different four directions from the center, and its crystal size is about 100mum. ABS resin is used as matrix resin, and the content of the whisker is made 0-70wt.%, and a specimen is produced by precompound system by molding by injection molding into a definite shape after forming pellets beforehand by mixing the resin and the whisker. Thus, the modulus of elasticity is increased, and on condition that wall thickness is constant, bending rigidity is increased. Besides, since the specific weight is large as well, deformation and resonance never occur.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a material for speaker frames used in audio output equipment and the like. 2. Description of the Related Art In recent years, sound output devices such as televisions, stereos, radio-cassette players, etc. have been designed to have even better output sound pressure than before for the acoustic characteristics of speakers and speaker systems. Distortion rate and flatness are desired, and low magnetic leakage is also required for sbeekers and sbeeker systems used for video on TVs, etc., which is an increasingly important factor that affects acoustic and magnetic properties. It is being looked at. A conventional speaker frame will be explained below.

Traditionally, materials such as steel plates and die-cast aluminum have been used for speaker frames. However, when a speaker is constructed using these materials, magnetic leakage becomes large if the iron plate is used, and the appearance also lacks a luxurious appearance. In addition, although aluminum die casting has excellent magnetic leakage and appearance, it has the drawback of being extremely expensive. It is becoming increasingly common to use this method to form the shape of a speaker frame. Problems to be Solved by the Invention However, speaker frames using these materials have a low bending modulus of elasticity, which results in low rigidity and low specific gravity of the molded material, making it difficult to drive the speaker with a constant power. When this happens, it resonates with the speaker diaphragm, deforms the frame, causes peaks and valleys in the speaker's sound pressure-frequency characteristics, increases distortion rate, and deteriorates sound quality.

For this reason, conventional composites of these resin materials and various reinforcing materials have been carried out, but for example, fibrous reinforcing materials such as glass fiber are oriented in the flow direction of the resin during molding.
There are also problems in that the strength of the molded product is directional, which limits the reinforcing effect C on the resin material, and that granular reinforcing materials are brittle even though they have increased rigidity.

Furthermore, the specific gravity of these reinforcing materials is not so high, and it has not been possible to significantly increase the specific gravity of the resin material by compositing.

The present invention solves the above-mentioned conventional problems, and aims to provide a speaker frame material that has excellent magnetic properties and appearance, and has a molded product having high rigidity and specific gravity.

Means for Solving the Problems In order to achieve this object, the speaker frame material of the present invention is made of thermoplastic or thermosetting synthetic resin and zinc oxide in which crystals have grown in four different directions from the center. It has a structure in which whiskers with a high modulus of elasticity are mixed.

Due to this structure, the speaker frame material according to the present invention has a very high elastic modulus, and when compared with conventional resin moldings, the material for speaker frames according to the present invention has a very high elasticity when the wall thickness is constant. Since the rigidity is increased and the specific gravity is also large, a speaker frame molded using this material will not deform or resonate during the operation of the speaker, so the sound pressure-frequency characteristics of the speaker will be flat. This has the effect of reducing distortion. In addition, we use a material that uses thermofusible or thermosetting synthetic resin as a base material, and mixes whiskers with high elastic modulus made of zinc oxide, in which crystals grow in four different directions from the center mentioned above. As a result, the thermoplastic or thermosetting resin and the whisker are well intertwined, and compared to conventional needle-shaped whiskers or fibrous reinforcing materials, the elastic modulus can be made thicker, and at the same time, it has strong toughness. can be ensured,
No improvement in brittleness.

In addition, this speaker frame material uses a mixture of thermoplastic or thermosetting synthetic resin and whiskers with a high elastic modulus made of zinc oxide, in which crystals grow in four different directions from the center. When molded using a method such as injection molding, the reinforcing material is oriented by the flow of resin during molding, and the strength of the material becomes directional, like conventional needle whiskers or fibrous reinforcing materials. There is no phenomenon in which the strength becomes extremely weak, and the strength is equally excellent in all directions. In addition, this material for speaker frames has good compatibility between the synthetic resin and the whiskers, so it exhibits better moldability than conventional molding materials containing various reinforcing materials, and is capable of molding complex shapes. It is excellent in mass production. EXAMPLE Hereinafter, an example of the present invention will be explained in detail with reference to the drawings. (Example 1) Whiskers are zinc oxide whiskers, molecular formula...
ZnO, specific gravity...5.7, 4 different from the center
It has a so-called tetrapod shape in which crystals grow in different directions, and the crystal size is about 100 μm. ABS resin is used as the matrix resin, and the whisker content is 0 to 70w.
L%, resin and whiskers were kneaded in advance using a pre-compounding method to form pellets, and then molded into a certain shape by injection molding to prepare samples.

Figure 1 shows the relationship between whisker content and the flexural modulus of the prepared wipe. (Example 2) The same zinc oxide whiskers as in Example 1 were used as whiskers. The crystal size is also the same. Epoxy resin was used as the matrix resin, and it was cured with a polyamine-based curing agent. Bisphenol type Epicote 828 was used as the epoxy resin, and triethylenetetramine was used as the curing agent. The content of Wiss was 0 to 7 Qwt%, and after thorough kneading with Ebikoat 828, 1% triethylenetetramine was added to 100 parts by weight of Epicoat 828.
After adding 2 parts by weight and thoroughly kneading, a sample was prepared by molding into a predetermined shape using a casting method. FIG. 2 shows the relationship between the whisker content and the flexural modulus of the prepared sample.

As is clear from Figures 1 and 2, as the content of whiskers increases, the flexural modulus of the material increases. Bending elastic modulus is an important physical property value that indicates the evaluation of a speaker frame material.If this value is small, abnormal noise may occur in the frame, peaks and valleys may occur in the sound pressure-frequency characteristics of the speaker, and the distortion rate may increase. do. Table 1 shows the values of the physical properties of the materials in Examples 1 and 2 as a comparison with conventional speaker frame materials and the effects of whiskers and spines.

(Left below) (Table 1) Figure 3 shows whisker 3 of the materials used in the example construction.
A speaker frame is created by injection molding using a 0wt% material, and a speaker frame with a diameter of 12 cm assembled using this speaker frame is driven with a constant input, and the frequency characteristics of the vibration acceleration in the arm portion of the speaker frame are calculated. show.

For comparison, we also show the characteristics of a speaker frame assembled using a resin material made of only matrinox resin with no whiskers added, and a speaker frame of the same type molded from a conventionally used resin material reinforced with glass fiber. . The glass fiber was mixed with ABS resin as a matrix resin in an amount of 30 wtχ, as in the case of Whisker 1.

As described above, when the speaker frame according to this embodiment contains whiskers, the acceleration of vibration is small especially at 3 to 6 Kl{z, and the vibration does not occur much. Therefore, the speaker frame is a suitable material for the speaker frame. It can also be seen that the effect is greater than that of glass fibers mixed at the same weight ratio. Effects of the Invention As described above, the present invention uses a material made of a mixture of thermoplastic or thermosetting synthetic resin and whiskers made of zinc oxide with crystals grown in four different directions from the center as a material for a speaker frame. According to the material according to the present invention, since the bending elastic modulus is large, it is possible to realize a speaker frame that does not generate abnormal noise, flattens the sound pressure-frequency characteristics of the speaker, and reduces the distortion rate. be.

[Brief explanation of the drawing]

Figures 1 and 2 are diagrams showing the relationship between the amount of whiskers added and the flexural modulus of the material used in the speaker frame of the present invention, respectively, and Figure 3 is a diagram of the relationship between the amount of whisker added and the bending elastic modulus of the material used in the speaker frame of the present invention. It is a characteristic diagram which shows the frequency characteristic of the acceleration of vibration which shows the effect of the frame for speakers. Name of agent: Patent attorney Shigetaka Awano (wtl/.Kuma times, 7saya fat jA3δ Fig. whiskers.@-yi (wt5 times) :1l's x so

Claims (1)

[Claims] A speaker frame material made of a mixture of thermoplastic or thermosetting synthetic resin and whiskers made of zinc oxide with crystals grown in four different directions from the center.