JPS581399A - Flame-retardant center cap for speaker - Google Patents

Abstract

PURPOSE:To btain flame retardation by impregnating cap, made principally of cellulose fiber, with low formaline type melamine resin and an organic compound which contains phosphorus and nitrogen, and then heating and drying it. CONSTITUTION:A center cap is obtained by punching a sheet for the center cap made by paper sheeting principally of cellulose fiber such as wood pulp. This cap is dipped in or coated with a methanol mixed solution of a compound containing phosphorus and nitrogen and low formaline type melamine resin by spraying, brushing, etc., and then a heat treatment is carried out, for example, at about 100 deg.C for 15 minutes. Thus, a flame-retardant center cap is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a flame retardant center camp for speakers.

Generally speaking, speaker diaphragms are made mainly from cellulose fibers, but as they are inherently flammable, they are susceptible to fires, and are exposed to heat generated by the speaker voice coil due to excessive input, or to high-temperature environments such as those found in television cabinets. There was a risk of ignition or other fire. Therefore, various proposals have been made to make the diaphragm flame retardant, but the center cap of the speaker tends to be overlooked, and like the diaphragm, it is necessary to make it flame retardant. Therefore, as a flame retardant material for the center cap,
The use of inorganic asbestos is considered, but its large mass causes poor speaker sensitivity and is not desirable in terms of sound quality. On the other hand, when Center Camp is made of cellulose fiber, the flame retardant treatment agents include boric acid,
Examples include boron or chlorine compounds, but boric acid, boron, and the like are highly hygroscopic, resulting in a significant decrease in strength and an increase in weight, which impairs speaker sensitivity, making them unfavorable in terms of characteristics. In addition, chlorinated compounds have the major disadvantage of not only being hygroscopic but also generating odor gas when ignited.

The present invention has been made with attention to the above points, and provides a flame-retardant center cap for speakers that is of stable quality and does not adversely affect the vibration characteristics of the speaker, and that can be manufactured at low cost without requiring special equipment. The purpose is to provide.

Hereinafter, the present invention will be explained in detail with reference to the drawings.

Figure 1 shows an example of a cone speaker.
is a back plate, a pole piece 2 is placed in the center thereof, and a magnet 3 is provided on the peripheral edge. And plate 4 is magnet 3, pole piece 2
, together with the back plate l form a magnetic cap. A voice coil bobbin 6 carrying a voice coil 5 is inserted into the magnetic cap so as to be able to vibrate freely, and is supported by a damper 7. A cone 8 is connected to the bobbin 6 at its center hole, and a center cap 9 is further attached to the bobbin 6. The upper peripheral edge of the cone 8 is supported by the frame 11 via an edge 10, and the edge 10 is further fixed to the frame 11 by a gasket 12. Note that the lead wire of the voice coil 6 is connected to a terminal 14 on the side surface of the frame 11 via a tinsel wire 13.

Although the above is a known structure, in the present invention, the center cap 9 is made of flame retardant material along with the flame retardant cone 8 and gasket 12.

That is, this center cap 9 is made by impregnating a paper made mainly of cellulose fibers such as wood pulp and bast fibers with an organic phosphorus-containing nitrogen-containing compound mixed with a low-form melamine resin, and then heat-treating the material. It is made flame retardant by drying.

In the present invention, the reason why paper molding is used instead of a simple sheet as the material for the center cap is as follows.

That is, the center cap, like the diaphragm, has a specific ratio (E
/ρ) and to have an appropriate internal loss, after the paper is made, it is pressed by instantaneous heating (mold) or dried by instantaneous heating in an open state. Therefore, the surface is hard and the inside is soft.

On the other hand, in the case of a sheet, it is gradually dried on a roll over time, so that both the surface and the inside have approximately uniform physical properties.

Therefore, when impregnating the center cap with resin, etc.,
The degree of impregnation and adhesion to the surface and inside varies depending on the concentration of the solution, type of resin, curing agent, etc., but in the case of sheets, there are no racial differences.

In order to impart flame retardancy to such a center cap by impregnating it with a flame retardant, it is sufficient that the surface of the center cap is covered with the flame retardant, and it is not necessarily necessary to internalize the flame retardant. Therefore, in the present invention, impregnation when impregnating with a flame retardant to make it flame retardant means not only normal impregnation but also
This includes cases in which the center cap surface is simply covered, but rather has high water absorption, and therefore changes over time and causes a decrease in Young's modulus.In order to achieve flame retardancy, reduce the amount of flame retardant as much as possible, and use other components such as resin. It is important to add water to improve non-water absorption, Young's modulus, and suppress weight increase.

The organic phosphorus-containing nitrogen-containing compound used as a flame retardant in the present invention is an alcohol (
For example, it is soluble in ethanol and methanol, and does not contain harmful gas-generating components such as chlorine and bromine, unlike conventional products. As this organic phosphorus-containing nitrogen-containing compound, for example, a commercially available Flucol solution of a compound containing 17.1% by weight of phosphorus and 7.7% by weight of nitrogen can be used.

A flame-retardant diaphragm can be obtained by impregnating the organic phosphorous-containing nitrogen compound, but in the present invention, a low phosphorus melamine resin and an organic amine salt added thereto as a catalyst are also used. Low formal type melamine resin refers to so-called 3-methylol melamine obtained by reacting formalin and melamine, and has a lower formalin content than 6-methylol melamine, and is used in an alcohol-soluble state through condensation. By using this low hol type melamine resin,
Impregnation with a flame retardant improves water absorption, making it non-hygroscopic, and also improves heat resistance and provides excellent mechanical strength such as compressive strength and 31 tensile strength.

That is, according to the present invention, since the center cap is mainly made of cellulose fiber, the internal loss is large, and the mechanical strength (Young's modulus) is increased by impregnation with the low-hol type melamine resin, so that the center cap has excellent frequency characteristics. can be obtained.

Next, a method for manufacturing a flame-retardant center cap will be explained.

First, a center cap sheet mainly made of cellulose fibers such as wood pulp is paper-molded, and a center cap is obtained by die cutting. After immersing this cap in a methanol mixed solution of an organic phosphorus-containing nitrogen-containing compound and a low-form melamine resin, or applying it by spraying, brushing, etc.
For example, a flame-retardant center cap can be obtained by heat treatment and drying at 100° C. for 15 minutes.

The desired flame retardancy and hardness of the center cap can be obtained by changing the amount of phosphorus-containing nitrogen-containing compounds attached to the cap or their blending ratio, but the amount of tightening attached to the cap is 8 to 20% by weight. It is appropriate to do so. In addition, an organic phosphorous-containing nitrogen-containing compound is prepared by using a 5-20% alcohol solution, and combining the compound with a low phor type melamine resin,
The blending ratio of organic amine salt is 5 to 2o:o, t to 5 by weight
: Prepare a mixed solution so that the ratio is 0.1 to 3. As described above, in the present invention, since alcohol such as methanol is used as a solvent, even cellulose fibers that easily swell in an aqueous system can be rapidly treated while maintaining their shape.

Hereinafter, the present invention will be specifically explained with reference to Examples.

Example 1 A center cap with a diameter of 10 openings was paper-molded, and FLAMEGARD 5527 (
Made by Dainippon Ink) and B as a low-hol type melamine resin.
1:1 to ECAMINP PM-N (manufactured by the same company)
A flame retardant center cap that was impregnated with methanol diluted to 8% (by weight) and dried at 100℃ for 15 minutes was subjected to a combustion test and did not catch fire immediately after being removed from the disaster. I got the cap. This center cap exhibits excellent flame retardancy meeting the requirements of UL Standard 94-V-0.

Example 2 Paper molding of a center cap with a diameter of 8 cIl and BEC
A combustion test was performed on a center cap that was impregnated with an alcohol mixed solution containing 0% weight part of AMINEL, 0.5% weight part of organic amine salt, and FLAMEGARD 5527.20% weight part, and dried at 100°C for 15 minutes. Immediately after that, a flame retardant center camp with no ignition was obtained.

As described above, according to the present invention, flame retardance can be imparted by impregnating an inherently flammable center cap made mainly of cellulose fibers with a treatment solution containing the center cap, thereby reducing the possibility of heat generation in the speaker voice coil. Alternatively, it can be used without causing any danger even in cases where it is easily exposed to high temperatures, such as a television scene cabinet.

[Brief explanation of the drawing]

The drawing is a longitudinal cross-sectional view of the Cone-Su force according to the present invention. 7... Damper, 8... Cone, 9... Center cap, lO... Edge, 11... Frame, 12
...Get gas. Patent applicant Pioneer Corporation Mogami Electric Co., Ltd.

Claims (1)

[Scope of Claims] 1. A flame-retardant speaker center made by impregnating a paper-molded camp mainly made of cellulose fibers with an organic phosphorus-containing nitrogen-containing compound mixed with a low-hol type melamine resin, and drying this by heating. cap. 2. The flame-retardant speaker center camp according to claim 1, wherein the low-form melamine resin is used together with an organic amine salt catalyst.