JPS6187500A - Diaphragm for loudspeaker - Google Patents

Abstract

PURPOSE:To simpify a work process and to improve the flexural rigidity by using a diaphragm obtained by sheet made of a natural fiber and a synthetic fiber, as a base material by sticking a thermosetting resin solution having a foaming property and bringing it to foaming hardening with heating. CONSTITUTION:A diaphragm base material 1 obtained by sheet making is formed by the mutual inter-fiber coupling of the natural fiber, the synthetic fiber or a fiber material 2 consisting of their mixture. There are spaces 3 between the fiber materials, the base plate 1 is dipped into the thermosetting resin solution having the foaming property and the solution is impregnated into he spaces 3. Thereafter it is brought to the foaming hardening with heating to obtain the diaphragm 4 for a speaker, and the diaphragm 4 is constituted with the fiber material 2 and the foaming material part 5 of the foaming thermosetting resin. In this way, a complicated work process and an unstable physical property, etc. are eliminated, a performance required for the diaphragm is satisfied and also the flexural rigidity can be improved.

Description

[Detailed description of the invention] 91L1 The present invention relates to a diaphragm for a speaker.

Generally speaking, the material for speaker diaphragms is lightweight, high density, low density, and moderate acoustic internal loss in order to obtain good output sound pressure frequency characteristics of the speaker. In addition, high bending rigidity is required. The higher the Young's modulus and the lower the density, the higher the resonant frequency of the diaphragm and the wider the piston movement area, which widens the frequency band of the speaker, and the larger the internal loss, the less the split resonance of the imaging plate. Frequency characteristics become flat. Furthermore, if the diaphragm is soft or has a high vibration frequency, partial vibrations will occur and the characteristics will deteriorate, so the bending rigidity must also be large.

For this reason, foamable materials have long been attracting attention as materials for diaphragms. There are methods such as a method in which the material is mixed with a mixture and then heated and foamed, and a method in which powdered foamable plastic is filled into a mold and then subjected to processing such as heating and pressurization to form the material.

That is, by using a foamable material, it becomes possible to reduce the density and increase the Nm, thereby improving the efficiency of the speaker. Also, sufficient acoustic internal loss can be obtained.

However, such conventional techniques have the following problems. In other words, in the case of the method of pasting foamed materials, it is difficult to uniformly paste materials having the same foaming ratio to the base material. Furthermore, in the case of a method of mixing unexpanded particles for papermaking, it is difficult to fix the particles to the substrate. In these cases, the physical properties of the diaphragm are unstable and the Young's modulus is extremely low.Also, in the case of a method in which foaming plastic is filled as a powder into a mold and then foam-molded, the plastic is It needs to be made into a powder, and the tasks such as filling, molding, and mold release tend to become complicated.Furthermore, there is little freedom in adjusting the physical properties of the resulting imaging plate, especially in terms of Young's modulus. I was only able to get a diaphragm with the same performance.

An object of the present invention is to provide a speaker side moving plate that can freely obtain good physical properties depending on the purpose while suppressing a decrease in Young's modulus.

The speaker diaphragm of the present invention is produced by C-paper-making using natural fibers, synthetic fibers, or a mixture thereof as raw materials, and an unfoamed foamable thermosetting resin is adhered to the fiber material in the resulting diaphragm. It is characterized in that the adhered thermosetting resin is foamed.

Friend-LJL An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1(a) shows a diaphragm base material 1 obtained by papermaking. The diaphragm base material 1 is formed by mutual interfiber bonding of giN materials 2 made of natural fibers, synthetic fibers, or a mixture thereof, as shown in FIG. 1(b). There is a gap 3 between the fibrous materials. The diaphragm base material 1 is dipped into a foaming thermosetting resin solution for a little while, and the gap 3 is impregnated with the solution.

Figure 2 (a>
This is a speaker diaphragm 4 shown in FIG. Speaker diaphragm 4
is as shown in Figure 2(b)! It consists of a fiber material 2 and a foamed material part 5 made of foamed thermosetting resin.

By using an organic solvent such as thinner as the solvent for the thermosetting resin, the solution of the resin enters the gap between the uA fibers and removes the resin.
1. Adhere to the fiber material. Further, the ability of the resin solution to adhere uniformly to the fiber material in the gaps depends on the bonding force between the iam4ii materials. For example, by using a raw material with a high degree of beating when making the base material, by adding an internal sizing agent such as rosin, or by increasing the pressing pressure during drying using a hot press, strong interfiber bonds can be created. This makes it difficult for the resin solution to penetrate inside.

Therefore, the speaker diaphragm in this example uses hollow TA fibers and raw materials with a relatively low degree of beating as raw materials, and is dried without pressing to create a relatively wide gap between fiber bonds. The photographic plate obtained by adhering the thermosetting resin to the inside also has foamed material portions on the surface and inside.

The speaker diaphragm of this example is obtained through the manufacturing process shown in FIG.

First, in the beating step S1, kapok, which is generally known as hollow '4X I'd, is beaten to a degree of beating of 20 to 22 degrees SR.

Next, in the papermaking process $2, the beaten material is used as a raw material, and without using a sizing agent, it is made into paper in a predetermined shape and size, and dried to form a base material.

Next, in the impregnation step S3, the obtained base material is immersed in the foamable thermosetting resin solution prepared in the ΔI fat liquid preparation step S4, and the thermosetting resin solution is poured into the base material. It is impregnated with water and attached to kapok fiber.

Thereafter, in a drying step S5, the impregnated base material is heated in a dryer with hot air at 80 to 100'C for about 10 minutes, thereby drying and foaming it to harden it. At this time, a pressure of about 1.0 to 2.0 kg/Cm2 may be applied as necessary.

In the resin liquid preparation step S4, novolac and thinner are mixed at a weight part mixing ratio of about 1:4 to 1:6 to dissolve novolak, and then 8% to 10% of the resulting liquid is mixed.
A foaming agent is added at a ratio of 10% by weight Φ, and after stirring, a curing agent is added at a ratio of 8% to 10% by weight to the resulting liquid to create a thermosetting product that has foaming properties. The resin solution is (q).

In this example, since a novolac type phenolic resin is used as the curable resin, for example, azodecarbonamide or azobisisobutylnitrile is used as a blowing agent, and hexamethylenetetramine or the like is used as a curing agent. do. Note that the foaming ratio can be changed depending on the purpose by changing the heating foaming conditions in the drying step.

The physical properties of the speaker diaphragm of the present invention thus obtained and the physical properties of the speaker diaphragm made only of the base material are
Not shown in the table.

Table 1 First, the diaphragm of this example effectively reduces internal loss l'J, and there is no decrease in Young's modulus. Also, the IC1 density did not increase. Moreover, the surface thickness increases and the stiffness increases significantly. This is because the resin solution foams and hardens to the inside of the diaphragm. In this example,
Because the foaming ratio is set to match the density to the base material, there is not much difference in Young's modulus, but the bending rigidity is greatly improved even with 100% Kapok base material, which was previously considered difficult to use. This allows it to be used without losing its characteristic low density. This means that even when using natural fibers or synthetic fibers, it is easy to select the raw materials and papermaking conditions to obtain interfiber bonds with as wide a gap as possible in the resulting base material. It is possible.

Further, in the above embodiment, the novolac type foamable phenolic resin was attached to the entire diaphragm, but it is also possible to attach it partially. For example, by impregnating the base material after papermaking with a polyurethane resin solution or the like to form a film on the surface, and then applying the novolac type foamable phenol resin to, for example, the part near the etch of the diaphragm, that is, near the outer periphery. In particular, the performance of the diaphragm can be improved, such as by suppressing split vibration during high-frequency reproduction.

11 As described above, according to the present invention, a diaphragm obtained by paper-making of natural fibers and synthetic fibers is used as a base material, and a thermosetting resin solution having foaming properties is attached to the base material, and the foaming property is formed by applying heat to the diaphragm. By hardening, it eliminates the complexity of the work process and the instability of physical properties, and also satisfies the performance required for a sliding plate, maintains the performance of the base material, and increases the bending rigidity. It can be significantly improved.

Further, by changing the raw material of the base material, its papermaking conditions, and drying conditions, it is possible to obtain an excellent single-phase speaker material having physical properties suitable for the purpose.

[Brief explanation of drawings]

FIG. 1(a) is a sectional view of the base material of the speaker diaphragm according to this embodiment, FIG. 1(b) is a partially enlarged sectional view of FIG. 1(a), and FIG. FIG. 2(b) is a partially enlarged sectional view of FIG. 2(a), and FIG. 3 is a flowchart showing the manufacturing process of the speaker diaphragm according to this embodiment. Explanation of symbols of main parts 1 ... Base material 2 ...
M-fitting material 3...Gap 4...Speaker diaphragm 5...Foamed material part

Claims (3)

[Claims] (1) Paper-making using a fiber material made of natural fibers, synthetic fibers, or a mixture thereof as a raw material, adhering a foamable thermosetting resin to the obtained diaphragm base material, and foaming the adhered thermosetting resin. A speaker diaphragm that is characterized by a . (2) A diaphragm for a speaker according to claim 1, characterized in that the diaphragm base material is impregnated with a solution of the thermosetting resin to adhere the thermosetting resin to the fiber material. . (3) The speaker diaphragm according to claim 1 or 2, wherein the thermosetting resin is a novolac type foamable phenolic resin.