JP2932625B2 - Manufacturing method of speaker diaphragm - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a speaker diaphragm used mainly for a speaker incorporated in audio equipment.

2. Description of the Related Art Although a speaker diaphragm made of mixed mica paper has been developed and manufactured in the past, the specific elastic modulus (Young's modulus / specific gravity) and internal loss (ta) required for a speaker diaphragm are known.
nδ) did not satisfy both physical properties. Conventionally, a method of impregnating a thermosetting resin such as an epoxy resin into a vibrating plate made of 100% laminated mica papermaking material and drying by heating, and a method of laminating mica having a relatively high aspect ratio,
The pulp and the binder have been mixed, and a speaker diaphragm has been obtained through means such as papermaking and heating press. Table 1 shows the speaker diaphragm No. 1 of the present invention and the conventional speaker diaphragm N.
The physical characteristics of o.2 to No.4 were compared. No.2 speaker diaphragm is 50% of mica 50% (weight ratio) with average aspect ratio of 250 and pulp material is N.UKP, beating degree SR20 degree is 50%
(Weight ratio) Mixed papermaking, drying with hot press, molecular weight 380
10% impregnated with a highly permeable epoxy resin based on the total weight and heat-treated. For No.3, No.2 laminated mica and pulp were mixed at a weight ratio of 50% each, and as a paper strength enhancer, a polyacrylamide anionic resin was blended at 2% with respect to the total weight of the laminated mica and pulp. Fixed with aluminum sulfate. No. 4 is 100% softwood unbleached kraft pulp (N.UKP) with the same strength and binder as No. 2 blended at a beating degree of SR20 degrees, followed by papermaking and hot pressing. No. 4 is an integrated mica 100 with an average aspect ratio of 250
% Of a 380 molecular weight epoxied epoxy resin is impregnated with 10% of the total weight and heat-treated. Table 1
In terms of specific elastic modulus and internal loss, No.2 and No.5 use resin with high permeability, so that resin (epoxy) penetrates and hardens to the whole diaphragm, and the bonding strength increases. Although the elastic modulus is improved, the internal loss is reduced, and the diaphragm is disadvantageous in terms of the strain rate.

Problems to be Solved by the Invention As described above, in the conventional method of manufacturing a diaphragm for a speaker, a material having a high specific modulus and a high internal loss cannot be obtained. Although effective in improving the elastic modulus, it was difficult to maintain the internal loss peculiar to pulp.

SUMMARY OF THE INVENTION An object of the present invention is to provide a stable speaker diaphragm excellent in specific elastic modulus and having a large internal loss while eliminating such conventional disadvantages.

Means for Solving the Problems As a method for solving the above-mentioned problems, the present invention is to make paper mixed with mica having a relatively high aspect ratio with pulp and dried with a hot press to maintain high internal loss with pulp. Then, by impregnating with resin with low permeability and drying, the mechanical strength of the skin part of the speaker diaphragm is improved as much as possible, and the center part in the thickness direction of the speaker diaphragm is bonded with pulp and mica. In order to obtain an internal loss.

Effect By the above method, it is possible to provide a speaker diaphragm having a stable characteristic with a sufficient internal loss.

Example Hereinafter, an example of the present invention will be described. That is, in the present invention, papermaking is performed by mixing paper with an aspect ratio of mica aggregates of 100 to 400 and pulp, drying by a hot press, impregnating with an epoxy resin having a low molecular weight of 1,000 to 2,000, which is a resin having low permeability, and drying. This is a cone-shaped speaker diaphragm as shown in FIG. 1, and a free edge 2 is attached to a peripheral portion of the speaker diaphragm. Next, a specific example of the present invention will be described.

・ Pulp: N.UKP 50% (weight percent) ・ Mica: Average aspect ratio 250 (100-400) 50%
(% By weight) ・ Direct dye: 3% (based on the total weight of pulp and mica) ・ Fixing agent: 3% of aluminum sulfate (based on the total weight of pulp and mica) ・ Epoxy resin: molecular weight 1000 (MEK diluted 15% solvent) As described above, the present invention relates to a speaker diaphragm having a specific elastic modulus and not impairing the internal loss. The mica having a high aspect ratio is mixed with pulp to form a paper, which is vibrated by means such as press molding and drying. The shape of the plate is obtained, and the viscosity of the epoxy resin itself is increased by impregnating the epoxy resin with a high molecular weight, so that the mica and the pulp fibers constituting the diaphragm hardly penetrate into the gaps. As a result, especially in FIG. The skin portions 1a and 1b are formed as shown, and the center portion 1c of the diaphragm is impregnated with a very small amount of epoxy resin, and the skin portions 1a and 1b are formed of a composite material having a high elastic modulus, Heart portion 1c is made of a configuration that maintains the characteristics of high pulp substrate loss. No. 1 in Table 1 shows the specific elastic modulus and the internal loss of the example of the present invention.

As shown by the frequency characteristics in FIG. 3A, a flat and high performance with a low peak dip and a high frequency limit was obtained. b shows the frequency characteristics of a conventional speaker diaphragm impregnated with an epoxy resin having a molecular weight of 380 (Table 1, No. 2 material and manufacturing method).

Effect of the Invention As described above, the present invention forms a composite material having a high elastic modulus on the skin portion of the diaphragm by mixing paper having a high aspect ratio of the mica aggregate with pulp and curing with a resin having low permeability. The central part has a structure that maintains the characteristics of a high-loss pulp base material, and specifies the speaker frequency (sound quality).
Can be greatly improved.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a speaker diaphragm manufactured by a method of manufacturing a speaker diaphragm according to an embodiment of the present invention, FIG. 2 is an enlarged cross-sectional view of the relevant part, and FIG. FIG. 5 is a frequency characteristic diagram of a speaker using a speaker diaphragm. 1 ... diaphragm for speaker, 1a, 1b ... skin part, 1c ...
Central part.

──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-60-10094 (JP, A) JP-A-58-156296 (JP, A) JP-A-51-70631 (JP, A) (58) Field (Int.Cl. ⁶ , DB name) H04R 7/02 H04R 31/00

Claims (1)

(57) [Claims] 1. A papermaking method in which the laminated mica has an aspect ratio of 100 to 400 mixed with pulp, dried by a hot press, impregnated with a resin having low permeability, and dried to increase the elastic modulus of the skin portion. A method of manufacturing a diaphragm for a loudspeaker, wherein a loss at a center portion is increased.