JPS6150493A - Diaphragm for speaker - Google Patents

Abstract

PURPOSE:To provide fire-resistant and to decrease danger of ignition by impregnating the solution of salt of a water soluble or alcohol soluble cyanamide derivative into a made paper material for a diaphragm, after drying, heating and pressuring to mold the diaphragm to a prescribed shape. CONSTITUTION:A diaphragm 25 for a speaker is manufactured. First, the material in which NBKP is beaten and adjusted to a beating degree 20 deg. SR is prepared. After that, it is dispersed, becomes suspension and paper is made by a prescribed shaped paper making net. At this time, as raw materials, NBKP 20 deg. SR 100%, a urea-type size agent 3%, a direct dye 4% and a fixing agent 1.5% are used. After paper making, the materials are made dry. After that, a paper material which is obtained by phospholic acid di-guanidine solution (alcohol solution is also preferable) with prescribed density is impregnated, an adhering quantity of phosphoric acid di-guanidien solution is adhered to paper materials up to 3%-15%, preferably, 7%-8%. Again, drying is executed. After that, the material is molded into a prescribed shape.

Description

[Detailed description of the invention] 11L” The present invention relates to a diaphragm for a speaker.

LL! LJL Generally speaking, a diaphragm for a speaker needs to be lightweight, have high rigidity, and have a moderate internal loss. In particular, paper diaphragms are widely used in speakers because of their good workability. FIG. 1 is a cross-sectional view of a cone-shaped speaker. The magnet 1 is held between an upper plate 2 and a lower plate 3, and a center pole 4 is placed on the lower plate 3, thereby forming a magnetic circuit. A voice coil bobbin 11 having a voice coil 6 wound thereon is coupled to the diaphragm 5 at the open end of the recess, and a center cap 15 is placed thereon. Vibration plate 5
The opening edge of the diaphragm 5 is supported along with the gasket 10 by the tip of the frame 8 fixed to the upper plate 2 via the edge 9, and the opening edge of the recess of the diaphragm 5 is supported by the damper 7 fixed to the frame 8. The coil 6 is supported via a bobbin 11.

Various attempts have been made to make the diaphragm of a speaker flame retardant because the voice coil of the speaker generates heat due to excessive input and is used in a location exposed to high temperatures, such as a television cabinet. However, the materials used for the diaphragm have traditionally been paper coated and impregnated with resin or paper mixed with flame-retardant fibers, both of which have the disadvantage of making the diaphragm itself heavy. Furthermore, since paper, which is a flammable material, is used, it is difficult to make the speaker flame-retardant and to make the diaphragm lightweight.

Therefore, it can be said that flame retardant measures for the diaphragm were insufficient for the speaker as a whole.

Conventional flame retardants for speaker diaphragms include boric acid, boron-based compounds, ha[]gen-based compounds, phosphoric acid-based compounds, and the like. Boric acid and boron-based compounds are highly hygroscopic and significantly deteriorate the moisture resistance of products. Halogen-based compounds themselves have a weak ability to impart flame retardancy to paper, and cannot be effective unless they are deposited between the strips.

Therefore, the use of these flame retardants makes the diaphragm heavy. Phosphoric acid compounds have a flame retardant effect on paper, but their decomposition temperature is low.For example, when molding a diaphragm, it is usually difficult to maintain its shape unless it is done at a temperature of 200°C or higher. Since the molding temperature and the decomposition temperature of the phosphoric acid flame retardant are almost in the same range, it is difficult to use it.

Another problem with halogen flame retardants is that they generate toxic gas when ignited.

SUMMARY OF THE INVENTION The present invention provides a speaker diaphragm that is lightweight and has sufficient flame retardancy.

The speaker diaphragm of the present invention is characterized in that it is made by impregnating a paper stock with a solution of a salt of a water-soluble or alcohol-soluble cyanamide derivative, drying it, and then heating and pressurizing it to form it into a predetermined shape.

Large-”1-1- Hereinafter, the present invention will be explained based on corrected drawings and tables.

In the present invention, >7t' which is a compound with a high decomposition temperature
A H'! rF@It゛, 86GCL, ka(7)!
Itt! By using a derivative with an atomic group of 1 (tsxJKeTh 1), a synergistic flame retardant effect can be achieved, and good flame retardancy can be imparted to a speaker diaphragm with a small amount of adhesion.

Cyanamide is represented by NG-NHZ, and its derivatives include, for example, guanidine of the following formula.

HNC(NH2)2 When used in the form of a salt of HNC(NH2)2 with phosphoric acid, for example, 1-guanidine phosphate, 2-guanidine phosphate, or sulfamic acid, the decomposition temperature is high and a synergistic effect with phosphorus and nitrogen or sulfur is obtained. Good flame retardancy can be obtained with a smaller amount of adhesion. Furthermore, cyanamide has low hygroscopicity and exhibits a flame retardant effect with a small amount of adhesion, so the speaker diaphragm of the present invention also has excellent moisture resistance.

In addition, the salt of guanidine sulfonomimate is J, l5K-0
According to the acute toxicity of Japanese medaka based on the 102 factory wastewater test method, the survival rate after 24 hours of 7oooppm is 1.
00%, and in a similar test with guanidine phosphate salt, the survival rate after 24 hours was 100% at 2500 ppm.
Met. These flame retardants have no problem with their acute toxicity, and since the flame retardant effect is due to the dehydration effect of phosphoric acid or sulfamic acid, no harmful gas is generated when ignited.

Application example 1 Manufactures speaker diaphragms.

First, NBKP is prepared by beating it and adjusting the beating degree to 20 degrees SR. Thereafter, it is dispersed in a papermaking tank to form a suspension, and paper is made using a papermaking net of a desired shape. At this time, the raw materials are used in the proportions shown in Table 1. After making the paper, it is dried. Thereafter, the obtained paper stock is soaked in an aqueous solution of diguanidine phosphoric acid (alcoholic solution may also be used) of a predetermined concentration.
The amount of guanidine attached is 3% to 15%, preferably 7% to 8
% to the paper stock. Let dry again. after that,
Form into a predetermined shape.

Table 1 NBKP 20 degrees SR100% Urea-based sizing agent 3% direct dye
4% fixative
1.5% Application Example 2 A paper stock is made and dried using the same raw material composition as in Application Example 1. Thereafter, the methylol melanin resin is applied to the paper stock by impregnation. The contact is then molded into a predetermined shape. At this time, diguanidine phosphate and methylol melanin resin can be mixed with the same aqueous solution or alcohol solution.

The flame retardancy of the cyanamide derivative in the present invention is determined by the amount of adhesion to the paper, and the concentration of the impregnated river solution has no effect on the flame retardancy.
; not influenced by However, the amount of adhesion can be adjusted by impregnating paper with it and then squeezing it with a roll or the like.

The flame retardance of the speaker diaphragms obtained in Application Examples 1 and 2 both corresponded to UL94V-0.

Furthermore, the diaphragm of the present invention and the conventional diaphragm will be assembled into a speaker in the same way and their frequency characteristics will be compared.

As shown in FIG. 2, there is almost no difference between the frequency characteristic curve B of a speaker using the diaphragm of the present invention and the frequency characteristic curve A of a speaker using a conventional diaphragm that is not subjected to flame retardant treatment. I understand.

The formula of the cyanamide derivative used in the above application example is as follows.

Phosphate 1 guanidine HNC (NH2) 2 H3POa phosphorus li 2 guanidine (HNC (N t L ) ) 2 H3P
O4 Guanidine sulfonate HN C(NH2) HS O3N H2 The flame retardant treatment in the present invention is not limited to paper, but can also be applied to other natural fibers, woven fabrics made of Chemical 111+H, and non-woven fabrics.

In particular, non-combustible or flame-retardant I! made of metal fibers, carbon fibers, glass fibers, synthetic fibers, etc. It has been confirmed that the flame retardant treatment according to the present invention is also effective for paper stocks made by mixing fibers in the paper stock.

For example, it can be applied to diaphragms made of wood pulp, etc.

t, 5. Paper, 7<1.7 equal force, 6. In the case of diaphragms (7), using a water-soluble impregnating agent may cause deformation, etc. Therefore, in this case, it is necessary to apply a sizing agent in advance. Further, it is also possible to impregnate and apply a flame retardant and then heat and pressurize it using a mold or the like.

The paper molding according to the present invention can be used not only for speaker diaphragms but also, for example, for center caps using paper.

Effects The speaker diaphragm of the present invention thus obtained is rigid because it is made of paper or the like and has an appropriate internal loss, making it suitable as a diaphragm. Also UL
It has excellent flame retardancy equivalent to 94V-0.

Furthermore, since cyanamide derivatives absorb little moisture, the obtained flame-retardant diaphragm does not deform due to moisture absorption and can maintain its shape in a stable state, so when assembled into a speaker, it can be A stable, lightweight diaphragm that does not affect its characteristics can be obtained.

As mentioned above, since it has excellent flame retardancy, the risk of ignition is significantly reduced compared to conventional speakers even if the speaker is placed in a high-temperature area near the power source of a television/radio or the like.

Please note that guanidine phosphate and guanidine sulfamate are non-toxic and their use is harmless to the human body.
No special ventilation equipment is required for its manufacture.

[Brief explanation of drawings]

FIG. 1 is a partial sectional view of a cone-shaped speaker, and FIG. 2 is a graph of a frequency characteristic curve of a speaker using a diaphragm according to the present invention. Explanation of symbols for main parts 1... Magnet 2... Upper plate 3... Lower plate 4... Center ball

Claims (3)

[Claims] (1) A diaphragm for a speaker, characterized in that a paper stock is impregnated with a solution of a salt of a water-soluble or alcohol-soluble cyanamide derivative, dried, and then heated and pressurized to form a predetermined shape. (2) The speaker diaphragm according to claim 1, wherein the solution of the water-soluble or alcohol-soluble cyanamide derivative salt contains a thermosetting resin. (3) The speaker vibration according to claim 1 or 2, wherein the paper stock contains metal fibers, carbon fibers, glass fibers, or synthetic fibers. Board.