JP2004242359A - Speaker diaphragm and method of manufacturing the same - Google Patents

Abstract

An object of the present invention is to provide a speaker diaphragm made of paper and having excellent water resistance.
SOLUTION: A water repellent is added to a slurry in which a mixture of a pulp mainly composed of natural pulp such as wood pulp and a fine pulp synthetic pulp is dispersed in water, and a water repellent is fixed to the pulp. Paper molding and drying and molding, impregnated with a synthetic resin solution mixed with a water repellent, and dried to form a water-repellent synthetic resin film on the surface of the molded article. It is possible to obtain a loudspeaker diaphragm that maintains high buckling strength even in a wet state and has strong water repellency and water resistance without impairing the properties of the plate and without requiring special jigs and equipment. .
[Selection diagram] None

Description

  The present invention relates to a speaker diaphragm used for an audio output device and the like, and a method for manufacturing the same.

  Conventionally, as a diaphragm for a speaker, paper mainly made of natural pulp such as wood pulp has been used. This is because, as the specific elastic modulus (E / ρ: E = elastic modulus, ρ = density) of the material of the diaphragm increases, that is, the diaphragm using a material having a higher elastic modulus and a lower density is used. High resonance frequency is high, it is possible to reproduce to higher frequency range, and it is possible to realize a speaker with a wide reproduction band. Also, the higher the internal loss of the diaphragm material, the flatter the frequency characteristics and the lower the distortion rate. Because of these, the paper has an appropriate elastic modulus and internal loss, and has a characteristic that cannot be obtained with a diaphragm formed of a synthetic resin or its composite because of its low density. It was from.

  However, paper diaphragms are vulnerable to humidity due to their hygroscopicity, and especially for diaphragms used for speakers that require water resistance, a water repellent is fixed to pulp fibers during paper diaphragm making. For example, a method of imparting water resistance, a method of obtaining a waterproof property by impregnating a synthetic resin solution after the paper diaphragm is formed and formed, and the like are used.

As prior art document information related to the invention of this application, for example, Patent Document 1 is known.
Japanese Utility Model Publication No. 57-109689

  However, recently, especially for speakers mounted on the doors of automobiles, water resistance has been required for detergents used in car washing, that is, surfactants such as so-called car shampoos. There has been a problem that sufficient water resistance cannot be obtained with a paper diaphragm impregnated with a synthetic resin solution after papermaking and molding to impart waterproofness by fixing a liquid agent.

  For this reason, a method of laminating and attaching a water-resistant synthetic resin film to the surface after paper forming of the paper diaphragm has been considered, but another method that requires a special jig and equipment for attachment is considered. Had issues.

  In the case of Patent Document 1, the speaker diaphragm itself is not made water-repellent, but a layer of a photo-curable resin is formed on the surface of the speaker diaphragm. Add new manufacturing equipment and processes such as substrates for UV irradiation, such as using polyvinyl alcohol at the time of papermaking for prevention, and also requiring UV irradiation for forming the photocurable resin layer. And other costs were inevitable.

  In order to solve the above-mentioned problems, a speaker diaphragm of the present invention is characterized in that a water repellent is added to a slurry in which a mixture of pulp mainly composed of natural pulp such as wood pulp and fine film-like synthetic pulp is dispersed in water. After adding and mixing and fixing the water repellent to the pulp, the molded article formed by papermaking and dried and formed is further impregnated with a synthetic resin solution mixed with a water repellent, and dried to form a water repellent on the surface of the molded article. This is a configuration in which a synthetic resin film is formed.

  This configuration eliminates water absorption inside and prevents water from penetrating from the surface without deteriorating the characteristics as a paper diaphragm, and does not require special jigs and equipment. It is possible to show water resistance to chemicals, and even if moisture penetrates into the interior, a fine film-like synthetic pulp that is water-resistant will form a film on the surface of natural pulp fibers such as wood pulp. Since these fibers are bonded to each other and bond these fibers together, a high buckling strength is maintained even in a wet state, and a speaker diaphragm having strong water repellency and water resistance can be obtained. .

  As described above, the speaker diaphragm according to the present invention is obtained by adding a water repellent to a slurry obtained by dispersing a mixture of pulp mainly composed of natural pulp and synthetic pulp in the form of a fine film in water and mixing the water repellent with the slurry. A molded product obtained by fixing and fixing to the pulp, and then formed and dried, is impregnated with a synthetic resin solution mixed with a water repellent, and dried to form a water-repellent synthetic resin film on the surface of the molded product. By eliminating the water absorption inside and preventing the intrusion of water from the surface without deteriorating the characteristics as a paper diaphragm and without requiring special jigs and equipment, It is possible to show resistance even if moisture enters inside, and fine pulp in the form of a film that has water resistance even if water enters inside binds to the surface of fibers of natural pulp such as wood pulp in a film form and becomes strong. This causes fibers, Since the teeth by binding, maintaining high buckling strength in a wet state, it has high practical value which can be obtained speaker diaphragm relatively low cost having strong water repellency, water resistance.

  Hereinafter, embodiments of the present invention will be described.

(Embodiment 1)
(Example 1)
Hereinafter, a speaker diaphragm according to a first embodiment of the present invention will be described.

  To a slurry of NUKP (unbleached kraft pulp) having a freeness of 550 cc (Canadian Freeness), a meta-type aramid resin pulp (trade name: Cornex Pulp: manufactured by Teijin Limited) is 10 wt% based on the absolute dry weight of NUKP. In addition, a fluorine-based water repellent (trade name: Dickguard, F-400: manufactured by Dainippon Ink and Chemicals, Inc.) was added at a ratio of 10 cc to the absolute dry weight of NUKP (100 g). Thereafter, the pH is adjusted to 4.5 to 5.0 with a sulfuric acid band, and the fluorine water repellent is fixed to NUKP.

  This slurry is formed into a wire mesh formed in the shape of a cone-shaped diaphragm, dehydrated, heated and dried in a male and female mold in the shape of a diaphragm heated to 200 ° C., and vibrated to a desired shape. Obtain a molded plate.

  Separately, a solution prepared by diluting 50 g of a saturated copolymerized polyester resin solution (trade name: Polyester, LP-011S50TO: manufactured by Nippon Synthetic Chemical Co., Ltd.) with 200 cc of methyl ethyl ketone was added to a fluorine-based water repellent (trade name: Surflon, SR-137AR: The impregnating solution was adjusted by adding 10 cc and stirring, and the molded article was immersed in the adjusted impregnating solution, air-dried at room temperature for about 10 minutes, and then dried in an oven at 120 ° C. After drying for a minute, a cone-shaped diaphragm having a diameter of 16 cm was obtained.

(Example 2)
Hereinafter, a speaker diaphragm according to a second example of the present embodiment will be described.

  Modified polyester fiber of 2 denier having a melting point of 130 ° C. and a fiber length of 5 mm was added to the NUKP slurry having a freeness of 550 cc at a freezing point of 10 wt% based on the absolute dry weight of NUKP, and the meta-type aramid resin pulp was added to the absolute dry weight of NUKP. 10% by weight, a dye and a water repellent were added and fixed in the same manner as in Example 1, and the paper was formed by the same method as in Example 1, followed by treatment with an impregnating liquid as in Example 1 above. As a result, a cone-shaped diaphragm having a diameter of 16 cm was obtained.

  As a water resistance test of the diaphragms of Examples 1 and 2, a cylindrical water storage tank was provided on the back of a speaker assembled using the respective diaphragms, and tap water and a commercially available automobile detergent (car shampoo) were used. The permeation state of the solution was observed by pouring an aqueous solution diluted to a predetermined concentration to a height of 30 mm. Neither tap water nor the detergent solution for automobiles penetrated into the side.

(Comparative example)
For comparison, as a conventional example, (1) As a conventional example 1, a fluorine-based water repellent and a dye were added and fixed to a NUKP slurry having a freeness of 550 cc in the same manner as in the above-mentioned Example 1, and this slurry was used as a diaphragm. A cone-shaped vibrating plate having a diameter of 16 cm, obtained by paper-making with a wire mesh formed into the shape of (1), dehydrating, and then drying by heating and pressing in a male and female mold in the shape of a vibrating plate heated to 200 ° C. As a conventional example 2, a slurry of NUKP having a freeness of 550 cc was made into a metal mesh formed into a diaphragm shape, dehydrated, and then heated and dried in a male and female mold in the shape of a diaphragm heated to 200 ° C. The molded product having the shape of the diaphragm obtained by the treatment was treated with the impregnating liquid in the same manner as in Example 1 above, and a immersion test as a water resistance test was similarly performed using a 16 cm-diameter cone-shaped diaphragm obtained by the treatment. Was done.

  As a result, in both of Conventional Examples 1 and 2, permeation to the surface of the diaphragm was recognized by tap water for 24 hours to 48 hours, and for automotive detergent liquid by 1 hour.

  Further, after the cone-shaped diaphragms of Examples 1 and 2 and Conventional Examples 1 and 2 were immersed in the above-mentioned detergent solution for automobiles for 24 hours, the cone-shaped diaphragms in a wet state were placed face down on a surface plate and vibrated. Place a disk on the neck of the plate, apply a load on the disk in a state where the platen and the disk are parallel to each other, measure the strength at which the diaphragm buckles, and measure the strength before the test (not immersed). The results of comparison with the strength are shown in Table 1 together with the reduction rate.

  As shown in (Table 1), it can be seen that the diaphragms of Examples 1 and 2 of the present invention have a lower buckling strength reduction rate and a higher buckling strength than the conventional examples. Also, it can be seen that the diaphragm according to Example 2 has a lower rate of reduction than the diaphragm according to Example 1 and retains a high buckling strength. It has been clarified by microscopic observation that the mixed, high-strength, water-resistant, low-melting polyester fiber is melt-bound at the intersection during heat-drying molding to form a three-dimensional network structure. This is considered to be due to the effect of the polyester fiber.

  In the above example, the pulp material mainly composed of natural pulp was mixed with a low-melting polyester fiber, but it was water-resistant, and aramid was well compatible with pulp, as long as a similar effect was obtained. However, the material and shape are not particular.

  As the water repellent, fluorine-based ones are used for pulp fixing, impregnating, and synthetic resin addition, but the material is not limited as long as the same effect can be obtained.

  Furthermore, a saturated denatured polyester resin was used as the synthetic resin for impregnation. However, if the resin film has good film-forming properties after drying and does not impair the characteristics of the paper diaphragm in terms of characteristics and sound quality, an acrylic resin is used. The material is not limited, including resin.

  The present invention makes it possible to provide a diaphragm for a speaker having excellent durability by subjecting a diaphragm for a speaker mainly composed of natural pulp excellent in versatility to water repellent treatment. It is intended to be used for indoor and outdoor audio equipment.

Claims (2)

A mixture of a pulp mainly composed of natural pulp such as wood pulp and a synthetic pulp in the form of a fine film is added to a slurry in which water is dispersed and mixed with a water repellent to fix the water repellent to the pulp. A speaker is obtained by drying and forming the same to obtain a predetermined shape, further impregnating the formed product with a synthetic resin solution containing a water-repellent agent, and drying the formed product to form a water-repellent synthetic resin film on the surface. Manufacturing method of diaphragm for use. The speaker diaphragm according to claim 1, wherein a pulp made of a meta-type aramid resin is used as the fine film-like synthetic pulp.