JPH0223799A - Diaphragm for electroacoustic transducer - Google Patents

Abstract

PURPOSE:To improve durability and heat stability by providing the film layer of special ethylene copolymer resin on the surface of a diaphragm whose main raw material is natural fiber. CONSTITUTION:The film layer 2 made of the ethylene copolymer resin containing mono-carboxylic acid, di-carboxylic acid, di-carboxylic acid anhydride and the metallic chloride of those is provided on the surface of the diaphragm for an electroacoustic transducer such as a speaker, whose main raw material is the natural fiber. Then, a diaphragm fiber layer 1 and the film layer 2 adhere extremely strongly to each other and become one body, and the diaphragm improved in its durability and its heat stability is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a diaphragm for an electroacoustic transducer such as a speaker.

(Prior Art) Conventionally, diaphragms made of natural fibers, mainly those made from wood pulp, have been the mainstream of diaphragms, taking advantage of their light weight and low cost.

However, due to the nature of natural fibers, it is difficult to provide sufficient waterproofness, and since fibers are the main component, they are breathable, making it difficult to reduce the weight beyond a certain limit.

In order to improve these shortcomings, for example,
No. 5219 is a speaker diaphragm made by heat-pressing a thermoplastic film sheet onto a paper cone, or the special public interest publication No. 55-3.
No. 2320 discloses a diaphragm etc. in which a polyurethane elastomer sheet is adhered to the surface of cone paper.

(Problems to be Solved by the Invention) However, these disclosed conventional techniques have not achieved sufficient results regarding the adhesive strength between the diaphragm mainly composed of natural fibers (hereinafter referred to as the diaphragm body) and the film. I couldn't get it. The adhesive strength between the diaphragm body and the film is one of the most important factors, and local adhesion failure can be a fatal defect in diaphragms that are violently driven by voice coils and the like.

For this reason, polypropylene, polyethylene, and polyurethane are used as the film to be attached to the diaphragm.

A variety of materials were investigated, including polyamide, EVA, polyester, and vinyl acetate copolymer, but nothing satisfactory could be obtained. Furthermore, the method of coating the adhesion surface of the film with an adhesive in order to improve the adhesion of the film requires a complicated process, resulting in variations in quality and high costs.

The present invention has been proposed in view of the above, and its purpose is to provide a vibrator for electroacoustic transducers that has excellent adhesiveness, durability, and waterproofness, and is inexpensive, without unnecessarily complicating the process. The purpose is to provide a board.

(Means for Solving the Problems) In order to achieve the above object, in the present invention, monocarboxylic acid, dicarboxylic acid, dicarboxylic acid anhydride and metal chloride thereof are added to the surface of a diaphragm mainly composed of natural fibers. A film made from ethylene copolymer resin containing
Adsorption was carried out by heating without coating the adhesive.

Further, more detailed examples of the above-mentioned soft adhesive resin as the film material are as follows.

■Those containing monocarboxylic acids include ethylene acrylic acid, ethylene methacrylic acid, etc.■Those containing dicarboxylic acid include ethylene ethyl acrylate maleic acid, etc., and dicarboxylic acid anhydrides include ,
Ethylene, ethyl acrylate, maleic anhydride, etc.
, these metal chlorides include ethylene methacrylic acid, metal methacrylate, ethylene ethyl acrylate metal maleate, etc. Also, polyethylene, ethylene vinyl acetate copolymer, ethylene ethyl acrylate copolymer It also includes graft copolymerization of acrylic acid, maleic anhydride, etc. to ethylene/methyl methacrylate copolymer.

Of course, the examples herein do not limit the scope of the claims.

(Function) In the present invention, by containing acid groups while maintaining durability,
The film utilizes the properties of an ethylene copolymer, which has excellent adhesion to paper, and is heated and adsorbed onto the diaphragm body to improve adhesion.

(Example) An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a diagram showing the structure of a diaphragm for an electroacoustic transducer according to the present invention, and FIG. 2 is an explanatory diagram of how a film is heated and adsorbed onto the diaphragm body.

In FIG. 1, A is a diaphragm, 1 is a diaphragm fiber layer, and 2 is a diaphragm film layer. In FIG. 2, 3 is a diaphragm body, 4 is a film, 5 is a clamp device that holds the film 4, 6 is a heater that heats the film 4, and 7 is a diaphragm having a suction hole 8 and a plurality of exhaust holes 9. The receiver of the main body 3 is a jig.

Next, an example of manufacturing a diaphragm will be explained with reference to FIG.

(1) First, a diaphragm main body 3 with a thickness of about 500 μm is prepared by making paper from 100% wood pulp and press-molding it into a predetermined shape, and a vibration temporary support is placed on a jig 7.

(2) A film 4 with a thickness of about 50μ is made by extrusion molding of ethylene/ethyl acrylate/maleic anhydride terpolymer resin (product name: Hondain TX-8030 manufactured by Sumika CDF) and held by a clamp device 5. do.

(3) Apply electricity to the heater 6 to soften the film 4. The temperature at this time is about 80°C.

(4) Using a vacuum pump (not shown), the vibrating temporary support sucks out the air inside the jig 7 through the suction holes 8, and causes the film 4 to be attracted to the diaphragm body 3.

(5) If you keep this state for 20 seconds, the film will be 4
becomes above the melting point by the heater 6, and is bonded to the diaphragm body 3. The temperature of the film 4 at this time is about 150°C.

(6) Turn off the power to the heater 6, and after confirming that the temperature of the film 4 has fallen below its melting point and has adhered to the diaphragm body 3, stop the suction, remove the film 4 from the clamp device, and take out the diaphragm A.

The diaphragm A thus obtained has a structure consisting of a fiber layer 1 and a film layer 2, as shown in FIG.

(Effects of the Invention) As described above, according to the present invention, the diaphragm fiber layer and the diaphragm film layer are extremely tightly adhered and integrated,
A diaphragm with excellent durability and thermal stability can be obtained.

In addition, the diaphragm film layer is about 1/10th the thickness of the diaphragm fiber layer, so it is completely waterproof and has no air permeability, without sacrificing the original lightweight and inexpensive characteristics of the diaphragm.
It has high industrial value.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing the structure of a diaphragm for an electroacoustic transducer according to the present invention, and FIG. 2 is an explanatory diagram of manufacturing the diaphragm in one embodiment. A... diaphragm, 1... diaphragm fiber layer, 2... diaphragm film layer, 3... diaphragm body, 4... film, 6... heater, 7... vibration A temporary receiver is a jig.

Claims (1)

[Claims] Features: A film layer made of ethylene copolymer resin containing monocarboxylic acid, dicarboxylic acid, dicarboxylic anhydride, and their metal chlorides is provided on the surface of the diaphragm, which is mainly made of natural fibers. A diaphragm for electroacoustic transducers.