JPS5847919B2 - Method for manufacturing flame-retardant speaker diaphragm - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is obtained by a novel processing method with fundamental improvements.

The present invention relates to a method of manufacturing a speaker diaphragm having excellent flame retardancy and acoustic radiation characteristics.

Conventionally, flame-retardant subica diaphragms are made by impregnating a paper pulp diaphragm that has been made and molded with single substances such as halides, phosphate esters, and ammonium phosphate, or mixtures thereof, or solutions of these compounds. Alternatively, ammonium polyphosphate, antimony oxide, etc. were added to the paper pulp in a beater during beating, and the paper was then finished.

However, with the former diaphragm, even if the concentration of the solution is kept constant,
It is difficult to maintain a constant degree of impregnation, resulting in large variations in the quality of the obtained products.Furthermore, impregnation clogs the fiber structure, greatly increasing the density. As a result, the physical properties deteriorate.

In addition, in order to obtain a sufficient flame retardant effect, a large amount of impregnating agent must be added to increase the weight by 30 times or more.

This causes the acoustic radiation efficiency of the subica diaphragm to decrease.

Furthermore, when assembling the subveaker, since the flame retardant such as phosphoric acid ester is liquid and non-drying, the surface of the diaphragm is in a wet state, so there is a drawback that the adhesive is difficult to apply and does not adhere.

The latter diaphragm is superior to the former diaphragm in that the processing process is simple and there is less variation in the quality of the finished diaphragm, but the yield rate of the flame retardant added in the beater is low and the oxidation Due to antimony's toxicity, wastewater from papermaking could become a source of pollution.

The present invention is a method for manufacturing a speaker diaphragm having both excellent flame retardancy and acoustic properties, which improves upon these conventional drawbacks.

The present invention impregnates an aqueous solution of ammonium polyphosphate obtained by reacting urea and phosphoric acid into an aggregate of cellulose fibers such as paper pulp or cotton, and then heats and reacts the fibers after drying to produce cellulose ammonium phosphate fibers. This is a method for producing a flame-retardant speaker diaphragm, in which the material is finished by cutting it alone or by mixing it with paper pulp.

Next, one embodiment of the present invention will be described.

Wood pulp was immersed in an ammonium polyphosphate solution obtained by mixing 4 moles of urea and 1 mole of phosphoric acid and heating and condensing the mixture, and after a few hours, it was squeezed to obtain a material with about 60 parts of ammonium polyphosphate attached to the weight of the wood pulp. Dry, 140-160℃ after drying
, a heating reaction is carried out for 15 minutes to obtain ammonium cellulose polyphosphate fibers.

This ammonium cellulose polyphosphate fiber alone is made into paper using a normal paper making method to form a speaker diaphragm.

That is, in the manufacturing method of the present invention, in the manufacturing process, ammonium polyphosphate is chemically bonded to cellulose through an esterification reaction to obtain flame-retardant ammonium polyphosphate cellulose fibers, and then this fiber is made into paper. Therefore, it is possible to obtain a subica diaphragm that not only has excellent flame retardancy, but also has a low density, a high Young's modulus, and has far more suitable acoustic properties than conventional products.

Table 1 shows the density, Young's modulus, and oxygen index, which are indicators of the acoustic properties of each subica diaphragm. , 3 dipromprovir) phosphate-impregnated sveaker diaphragm, (3) is the sveaker diaphragm of the above embodiment of the present invention.

As mentioned above, considering the reason why the diaphragm of the present invention has excellent characteristics, it is found that during the manufacturing process of the conventional diaphragm, flame retardant such as phosphoric acid ester is added between the fibers of the molded diaphragm. The bond between the fibers is weakened by the intrusion or by the fact that particles of a flame retardant added in a powdered substance such as antimony oxide are sandwiched between the fibers of the diaphragm.

Therefore, in the conventional diaphragm, the paper fibers are filled with flame retardant, so the density is low, and the bond between the fibers is weak, so the Young's modulus is low.

In contrast, in the diaphragm of the present invention, the fiber diameter increases due to the esterification reaction, increasing its rigidity, and the introduction of phosphoric acid increases the hydrophilicity of the fibers, making them extremely swellable. The bond is strong, the density is small, and the material has a high Young's modulus.

During the manufacturing process, the amounts of the impregnating agent and the agent to be impregnated can be freely adjusted, and the amounts can also be finely adjusted during papermaking, so there is very little variation in quality.

Furthermore, since the materials used during the process are non-toxic, there is no risk of causing pollution.

Claims (1)

[Claims] 1. An aqueous solution of ammonium polyphosphate obtained by reacting urea and fiber acid is impregnated into an aggregate of cellulose fibers such as paper pulp or silk, and after drying, the mixture is heated and reacted to produce dry ammonium cellulose fibers. A method for manufacturing a flame-retardant subica diaphragm, in which the flame-retardant subica diaphragm is finished by cutting it alone or by mixing it with paper pulp.