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TECHNICAL FIELD The present invention relates to a method of manufacturing a damper for a
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 phenol resin or melamine resin, and then heat
molded. There are widely practiced methods of manufacturing so-called corrugation dampers
that are processed to have concentric waves.
In this manufacturing method, those mainly composed of a phenol resin as an impregnating
agent are most widely used from the viewpoint of various physical property management
required as a damper for supporting a vibration system of a speaker, cost and the like. It has
However, the phenolic resin containing formaldehyde generates harmful gases in the
manufacturing process, particularly in the drying process and the molding process, thereby
irritating the skin and causing cracks and scars. It is feared that it may cause adverse effects on
the worker's body, such as dizziness or nausea or asthma, depending on the person, and has the
inherent problem of causing environmental pollution in the vicinity.
Recently, in the production of dampers for loudspeakers, deimpregnation of the impregnating
agent or using no impregnating agent itself, for example, utilizing self-fusion by thermal melting
of a thermoplastic resin, punching out a thin resin plate Although various technological
developments such as new development of so-called butterfly dampers are prosperous, they are
all less versatile in terms of cost, productivity, and performance, and the dependence on phenolbased impregnating agents is still high. Is the current situation.
In recent years, with the rapid progress of natural destruction, a global response to
environmental protection is urgently required, and regulations on environmentally harmful
substances are strict, which is an extremely important issue in the manufacturing industry in
The applicant noted early on the importance of global environmental protection, and applied
non-wood pulp such as kenaf or banana to the diaphragm material for speakers as disclosed in
JP-A-6-253390 and JP-A-7-95685. Have developed research and development with a view to
forest resource conservation.
The present invention is also basically based on this concept, and the objective is to manufacture
a damper for a speaker, without requiring a large increase in cost, and without causing any
deterioration in performance, such as formaldehyde. By significantly reducing the generation of
poison gas, it is intended to improve the working environment and prevent environmental
pollution, thereby contributing to environmental protection.
[Means for Solving the Problems] In order to achieve the above object, the present invention is a
damper for a speaker in which a woven fabric or a non-woven fabric made of various fiber
materials is impregnated with an impregnating agent containing a phenol resin as a main
component In the production method of the present invention, urea is added to the impregnating
Further, according to the present invention, after impregnating a woven or non-woven fabric
made of various fiber materials with an impregnating agent containing a phenolic resin as a main
component, the urea resin is added to the phenolic resin as the impregnating agent in the
method of manufacturing the speaker damper. On the other hand, it is characterized in that the
above object is optimally achieved by adding 2.5 to 3.5% of the weight solid differentiation.
DETAILED DESCRIPTION OF THE INVENTION In the present invention, a predetermined amount
of urea is added to a phenol-based impregnating agent, which prevents the generation of harmful
substances such as formaldehyde.
Here, the reaction structure of urea and formaldehyde is described using a chemical reaction
Urea, when neutral or alkaline, reacts with formaldehyde to form water-soluble methylolurea and
In addition, methylol urea and dimethylol urea produced by this reaction are not subject to
environmental load substances and are not particularly problematic.
As the amount of urea is increased, the amount of residual formaldehyde decreases, but when the
amount of addition of urea is excessive, unreacted urea remains and 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 a phenol resin, it is possible to significantly reduce the generation of
formaldehyde in the damper manufacturing process, and achieve improvement in working
environment and environmental protection. .
EXAMPLES Examples of the present invention will be described below.
The impregnating agent according to the embodiment of the present invention is based on a
phenol resin as a main component and a predetermined amount of various modifiers mixed
therein, and this part is the same as that conventionally practiced, Furthermore, what mix |
blended urea suitably was diluted with methanol, and the impregnating agent of predetermined
concentration was prepared.
A cotton yarn is woven into a woven fabric as a substrate for dampers, impregnated with the
above-mentioned impregnating agent, and pre-dried at about 90 ° C. for about 2 minutes, and
then placed on a molding machine. C. for 3 to 4 seconds to form a number of concentric
corrugations, which were further processed by punching to obtain a desired damper.
When the amount of formaldehyde generated during the manufacturing process was measured,
it was confirmed that the amount of formaldehyde generated in the conventional damper
manufacturing process in which the impregnating agent did not contain urea was significantly
reduced, and further as a damper No deterioration in the performance was observed in the
results of the physical property measurement.
FIG. 1 shows the results of measuring the change in the amount of generated formaldehyde
relative to the amount of urea added to the impregnating agent (by means of a gas detector tube),
and the amount of urea added is shown by the weight solid content ratio to the phenolic resin.
As a result, when the amount of urea added was 3%, the amount of formaldehyde generated was
reduced to 10% or less of the conventional amount, and from the aspect of working environment
improvement as well as from the aspect of preventing environmental pollution, the purpose was
If the amount of urea is further increased to more than 3%, the amount of formaldehyde
generated will be further reduced, but conversely, the amount of ammonia generation will
increase, and the influence of the increase can not be ignored.
The amount of urea added is preferably in the range of 2.5 to 3.5% by weight to the solid content
of the phenolic resin, in order to satisfy the original purpose and to limit the adverse effect of
ammonia to a level at which problems do not occur. .
In addition, although the Example showed only what used the cotton cloth as a damper base
material, the same effect is acquired also when using the woven fabric or nonwoven fabric which
consists of various fiber materials, such as aramid fiber and phenol fiber, as a base material.
Needless to say.
In addition, although the present invention is directed to the manufacture of a damper for a
speaker, this technology is also applicable to other parts for a speaker using a resin made of
formaldehyde such as cloth edge material, voice coil varnish, etc. Expected enough.
As described above, according to the method of manufacturing a damper for a speaker of the
present invention, a relatively simple method of adding urea to a phenol-based impregnating
agent results in a large cost compared to the conventional manufacturing method. Can
significantly reduce the generation of formaldehyde, which is a serious problem in the
environment, without sacrificing performance and without sacrificing the basic performance as a
speaker damper, and it is versatile. It is possible to provide a certain speaker damper
manufacturing method.
As a result, the working environment of the manufacturing process of the speaker damper can be
improved, and the environmental pollution in the vicinity can be prevented, which greatly
contributes to environmental protection.
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jp2001103596, description
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