JP2001103596A - Method of manufacturing damper for loudspeaker - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance the working condition and also prevent environmental pollution by considerably reducing production of a poisonous gas such as formal dehyde without the need for a high cost increase and causing deterioration in the performance in the case of manufacturing a damper for a loudspeaker. SOLUTION: An urea to reduce production of formaldehyde is added to an impregnant of phenol base used for manufacturing the damper made of various fibrous materials being damper base materials.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a speaker damper.

[0002]

2. Description of the Related Art Conventionally, as a method of manufacturing a damper for a speaker, a woven or non-woven fabric made of various fiber materials such as cotton and aramid is impregnated with a thermosetting resin such as a phenol resin and a melamine resin, and then heated and molded. 2. Description of the Related Art A method of manufacturing a so-called corrugation damper having a concentric waveform by processing is widely practiced.

[0003] In this manufacturing method, phenol resin as a main component is most widely used as an impregnating agent from various aspects of physical property management and cost required as a damper for supporting a vibration system of a speaker. It has become mainstream.

[0004]

However, phenolic resins containing formaldehyde generate harmful gases in the production process, especially in the drying and molding processes, which irritate the skin and cause cracks and bruises. It is feared that it may cause harm to the worker's body, such as causing dizziness, nausea, and asthma, depending on the person, and there is an inherent problem that it also leads to environmental pollution in the vicinity.

[0005] Recently, in the production of speaker dampers, the use of dephenolization of an impregnating agent or the use of an impregnating agent itself, for example, the use of self-fusion by the thermal melting of a thermoplastic resin, or the use of a thin resin plate A variety of technological developments, such as the new development of the so-called punched butterfly damper, are being actively pursued, but these are cost, productivity,
From the performance point of view, none of them are generally versatile, and the reliance on phenol-based impregnants is still high.

[0006] In recent years, with the rapid destruction of nature, there is an urgent need to respond globally to environmental protection, and regulations on substances of environmental concern are strict. This is an extremely important issue especially in the manufacturing industry.

The applicant has been aware of the importance of protecting the world's natural environment from an early stage, and has disclosed in Japanese Patent Application Laid-Open Nos. Hei 6-253390 and
As disclosed in Japanese Patent No. 95685, research and development are being conducted with a view to protecting forest resources, such as applying non-wood pulp such as kenaf and banana to a diaphragm material for a speaker.

[0008] The present invention is also basically based on this concept, and the object is to manufacture a damper for a speaker without requiring a large increase in cost.
Further, it is intended to significantly reduce the generation of toxic gas such as formaldehyde without deteriorating performance, to improve the working environment, and to prevent environmental pollution, thereby contributing to environmental protection.

[0009]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a speaker damper for impregnating a woven or non-woven fabric made of various fiber materials with an impregnating agent containing a phenolic resin as a main component, followed by heat molding. Is characterized in that urea is added to the impregnating agent.

The present invention also provides a method of manufacturing a speaker damper, comprising impregnating a woven or non-woven fabric made of various fiber materials with an impregnating agent containing a phenolic resin as a main component and then subjecting the impregnating agent to urea. The above-mentioned object is optimally achieved by adding 2.5 to 3.5% by weight of the phenol resin to the phenol resin.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the present invention, a predetermined amount of urea is added to a phenol-based impregnating agent, and the generation of harmful substances such as formaldehyde is prevented by the impregnating agent.

Here, the reaction structure between urea and formaldehyde will be described using a chemical reaction formula. When urea is neutral or alkaline, it reacts with formaldehyde to form water-soluble methylol urea and dimethylol urea.

[0013] Methylol urea and dimethylol urea produced by this reaction are not subject to any environmentally hazardous substances, and there is no particular problem. As the amount of urea increases, the residual formaldehyde decreases,
If the added amount of urea is excessive, unreacted urea remains, and this is decomposed by heat during molding to generate ammonia.

Based on the above theory, by adding an appropriate amount of urea to the impregnating agent mainly composed of phenol resin,
The generation of formaldehyde in the damper manufacturing process can be significantly reduced, and the working environment can be improved and environmental protection can be achieved.

[0015]

Embodiments of the present invention will be described below. The impregnating agent according to the embodiment of the present invention is based on a mixture of a phenol resin as a main component and a predetermined amount of various modifiers,
This part is the same as that conventionally used, but further mixed with urea appropriately and diluted with methanol to prepare an impregnating agent having a predetermined concentration.

A base material for a damper is prepared by weaving a cotton yarn into a woven fabric, impregnated with the impregnating agent, and
After pre-drying for about 2 minutes at
A large number of concentric corrugations were formed by heating and molding at ℃ 270 ° C. for 3 to 4 seconds, and the corrugations were punched to obtain a desired damper.

When the amount of formaldehyde generated during the manufacturing process was measured, it was confirmed that the amount was significantly reduced as compared with the amount of formaldehyde generated in the conventional damper manufacturing process containing no urea in the impregnating agent. As a result of the measurement of the physical properties of the damper, no deterioration in performance was observed.

FIG. 1 shows the results obtained by changing the amount of urea added to the impregnating agent and measuring the change in the amount of formaldehyde generated (using a gas detector tube). The amount of urea added is shown by the weight solids ratio to the phenol resin. I have.

As a result, when the amount of urea added is 3%, the amount of formaldehyde generated is reduced to 10% or less of the conventional level, and the object can be achieved from the viewpoint of improving the working environment and preventing environmental pollution. Was. If the amount of urea is further increased beyond 3%, the amount of formaldehyde generated is further reduced, but on the contrary, the amount of generated ammonia is increased and the effect of the increase cannot be ignored.

In order to satisfy the original purpose and to keep the harmful effects of ammonia at a level that does not cause a problem, the amount of urea added is 2.5 to 2.5 wt.
A range of 3.5% is considered preferred.

Although only the examples using cotton cloth as the damper base material are shown in the examples, the same effect can be obtained when a woven or nonwoven fabric made of various fiber materials such as aramid fiber and phenol fiber is used as the base material. It goes without saying that you can get it.

Although the present invention is directed to the manufacture of speaker dampers, this technique is applicable to other speaker parts using a resin made of formaldehyde such as a cloth edge material and a voice coil varnish. The development of is also expected.

[0023]

As described above, according to the method of manufacturing a speaker damper of the present invention, a relatively simple method such as adding urea to a phenol-based impregnating agent can provide a large cost as compared with the conventional manufacturing method. Without significantly increasing the performance of the loudspeaker damper, without sacrificing the basic performance of a speaker damper. A method for manufacturing a speaker damper can be provided. As a result, the working environment of the manufacturing process of the speaker damper is improved, the surrounding environment is prevented from being contaminated, and the contribution to the protection of the environment is significant.

[Brief description of the drawings]

FIG. 1 is a graph showing the results of measuring the relationship between the mixing ratio of urea and the generation rate of formaldehyde in an impregnating agent.

Claims (2)

[Claims] 1. A method of manufacturing a speaker damper, comprising impregnating a woven or nonwoven fabric made of various fiber materials with an impregnating agent containing a phenolic resin as a main component, and then subjecting the impregnating agent to urea. A method for manufacturing a speaker damper, which is characterized by the following. 2. The method for producing a speaker damper according to claim 1, wherein the amount of urea added is 2.5 to 3.5% by weight solids ratio to the phenol resin.