JP2017046258A - Speaker diaphragm - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a speaker diaphragm excellent in both a Young's modulus and internal loss (tanδ).SOLUTION: A speaker diaphragm includes: a pulp material including cellulose nanofiber; and a sugar component which at least part of the pulp material is impregnated with. In accordance with an embodiment of the present invention, only part of the pulp material is impregnated with the sugar component. In accordance with another embodiment of the present invention, the pulp material further includes other pulp component than the cellulose nanofiber, and the content of the cellulose nanofiber is 1-50 pts.wt. with respect to 100 pts.wt. of the pulp component other than the cellulose nanofiber.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a speaker diaphragm.

  In general, characteristics required for a speaker diaphragm include a high Young's modulus (elastic modulus and rigidity) and a large internal loss (tan δ). Conventionally, materials for speaker diaphragms have been studied to meet such demands.

  For example, a technique for forming a speaker diaphragm using a material containing nanofibers has been proposed (Patent Documents 1 and 2). In such a technique, the Young's modulus can be improved by adding cellulose nanofibers. However, the internal loss (tan δ) does not improve sufficiently, but rather tends to decrease as shown in Patent Document 2.

JP 2013-42405 A JP 2011-130401 A

  The present invention has been made to solve the above-described conventional problems, and an object thereof is to provide a speaker diaphragm that is excellent in both Young's modulus and internal loss (tan δ).

The speaker diaphragm of the present invention includes a pulp material containing cellulose nanofibers and a sugar component impregnated in at least a part of the pulp material.
In one embodiment, the sugar component impregnates only a part of the pulp material.
In one embodiment, the said pulp material further contains pulp components other than the said cellulose nanofiber, and the content rate of the said cellulose nanofiber is 1 weight with respect to 100 weight parts of pulp components other than this cellulose nanofiber. Part to 50 parts by weight.
In one embodiment, the cellulose nanofiber is obtained from cellulose derived from bamboo.
In one embodiment, the sugar component is a monosaccharide or a disaccharide.
In one embodiment, the content rate of the said sugar component is 5 weight part-50 weight part with respect to 100 weight part of pulp materials.
According to another situation of this invention, the manufacturing method of the said speaker diaphragm is provided. This manufacturing method includes forming a pulp material using a pulp composition containing cellulose nanofibers and impregnating the pulp material with a sugar composition containing a sugar component.
In one embodiment, a sugar composition containing a sugar component is applied to the pulp material by an application method using a spray.

  According to the present invention, a speaker diaphragm that is excellent in both Young's modulus and internal loss (tan δ) by including a pulp material containing cellulose nanofibers and a sugar component impregnated in at least a part of the pulp material. Can be provided.

It is a schematic sectional drawing which shows an example of the speaker diaphragm by one Embodiment of this invention. It is a figure which shows the sound pressure frequency characteristic of the speaker diaphragm obtained in Example 1 and Comparative Example 1. FIG.

  The speaker diaphragm of the present invention includes a pulp material containing cellulose nanofibers and a sugar component impregnated in at least a part of the pulp material.

  In one embodiment, the speaker diaphragm of the present invention is formed by molding a pulp material using a pulp composition containing cellulose nanofibers, and impregnating the obtained pulp material with a sugar composition containing a sugar component. Can be obtained.

  The said cellulose nanofiber means the cellulose fiber whose fiber diameter is nanosize. The fiber diameter (number average diameter) of the cellulose nanofiber is, for example, 90 nm to 110 nm.

  The length (number average length) of the cellulose nanofiber is, for example, 5 μm to 15 μm.

  In the speaker diaphragm, the content ratio of cellulose nanofibers is preferably 1 part by weight to 50 parts by weight, more preferably 1 part by weight to 100 parts by weight of pulp components (described later) other than cellulose nanofibers. 10 parts by weight. Within such a range, a speaker diaphragm excellent in both Young's modulus and internal loss (tan δ) can be obtained.

  As a manufacturing method of the said cellulose nanofiber, the method of fibrillating a cellulose raw material by mechanical processing is mentioned, for example. Examples of the mechanical treatment include a treatment for refining a cellulose raw material using a low pressure homogenizer, a high pressure homogenizer, a grinder, a cutter mill, a jet mill, a short screw extruder, a twin screw extruder, an ultrasonic stirrer and the like. It is done. The cellulose nanofiber may be produced by defibrating a cellulose raw material by chemical treatment such as oxygen treatment or acid treatment.

  It does not specifically limit as said cellulose raw material, Arbitrary appropriate cellulose raw materials are used. Examples of the cellulose raw material include hardwood kraft pulp (LKP) such as hardwood bleached kraft pulp (LBKP), hardwood unbleached kraft pulp (LUKP), softwood bleached kraft pulp (NBKP), and softwood unbleached kraft pulp (NUKP). Kraft pulp derived from wood; waste paper pulp such as sulfite pulp and deinked pulp (DIP); ground pulp (GP), pressurized groundwood pulp (PGW), refiner groundwood pulp (RMP), thermomechanical pulp (TMP), Chemi Examples include mechanical pulps such as thermomechanical pulp (CTMP), chemimechanical pulp (CMP), and chemiground pulp (CGP). Moreover, you may use the powdery cellulose obtained by grind | pulverizing these pulps, and the microcrystalline cellulose obtained by refine | purifying pulp by chemical treatments, such as acid hydrolysis. Further, non-wood pulp derived from kenaf, hemp, rice, bagasse, straw, bamboo, cotton and the like may be used. In one embodiment, bamboo-derived cellulose is used as a raw material for cellulose nanofibers. If cellulose derived from bamboo is used, a speaker diaphragm having a higher Young's modulus can be obtained.

  Preferably, the pulp composition further includes pulp components other than cellulose nanofibers. Arbitrary suitable pulp can be used as pulp components other than a cellulose nanofiber, For example, said pulp is used. Moreover, only 1 type of pulp may be used independently and may be used in combination of multiple types. In addition, the said cellulose nanofiber and pulp components other than a cellulose nanofiber are distinguished by a fiber diameter. The fiber diameter of pulp components other than cellulose nanofibers is preferably 1 μm or more.

  In one embodiment, cocoon-derived pulp is used as a pulp component other than cellulose nanofibers. If the pulp derived from koji is used, the effect of impregnating the pulp material with sugar is remarkably exhibited, and in particular, a speaker diaphragm having a high internal loss (tan δ) can be obtained.

  In the speaker diaphragm, the content ratio of the cocoon-derived pulp is preferably 1 part by weight or more, more preferably 5 parts by weight or more, with respect to 100 parts by weight of pulp components other than cellulose nanofibers. Preferably it is 10 weight part or more.

  The freeness of pulp components other than cellulose nanofibers is preferably 150 cc to 700 cc, more preferably 200 cc to 600 cc. Within such a range, the effect of impregnating the pulp material with sugar is prominent, and in particular, a speaker diaphragm having a high internal loss (tan δ) can be obtained. Freeness is measured in accordance with JIS P 8121.

  Usually, the pulp composition further comprises water. Moreover, the said pulp composition may further contain arbitrary appropriate additives. Examples of the additive include pigments, dyes, fillers, sizing agents, wear resistance improvers, water resistance agents, surfactants, waxes, rust preventive agents, conductive agents, and paper powder fall-off preventing agents.

  Using the pulp composition, the pulp material is obtained by molding by any appropriate molding method. Examples of the method for forming the pulp material include a method of forming by papermaking.

  The sugar composition is preferably an aqueous solution of sugar or an alcohol solution. As alcohol, methanol, acetone, ethanol etc. can be used, for example. Preferably, it is methanol.

  As the sugar, monosaccharides or disaccharides are preferably used, and monosaccharides are more preferably used. If a monosaccharide is used, a speaker diaphragm having a higher internal loss (tan δ) can be obtained. Specific examples of monosaccharides include fructose and glucose. Specific examples of the disaccharide include sucrose.

  The sugar concentration of the sugar composition is preferably 3% to 50% by weight, more preferably 5% to 40% by weight, and still more preferably 10% to 30% by weight.

  In the speaker diaphragm of the present invention, at least a part of the pulp material is impregnated with the sugar component. Such a speaker diaphragm can be obtained by, for example, a method of immersing the pulp material in a sugar composition, or applying a sugar composition to the pulp material. Preferably, the speaker diaphragm is formed by applying a sugar composition to a pulp material. As an application method, an application method using a spray is preferably employed. By applying using a spray, it is possible to obtain a speaker diaphragm that is remarkably excellent in both Young's modulus and internal loss (tan δ).

  In the speaker diaphragm, the content ratio of the sugar component is preferably 5 to 50 parts by weight, more preferably 10 to 40 parts by weight, further preferably 100 parts by weight of the pulp material. Is 15 to 30 parts by weight.

  Preferably, in the speaker diaphragm of the present invention, the sugar component is impregnated only in a part of the pulp material. Such a speaker diaphragm can be obtained, for example, by applying a sugar composition to a pulp material. Preferably, an application method using a spray is employed.

  When the sugar component is impregnated only in a part of the pulp material, the thickness of the pulp material impregnated with the sugar component is preferably 1% to 90% with respect to the thickness of the pulp material. Yes, more preferably 5% to 80%.

  In one embodiment, a surface layer may be formed on the pulp material. FIG. 1 is a schematic cross-sectional view showing an example of a speaker diaphragm according to this embodiment. The speaker diaphragm 100 includes a pulp material 10 and a surface layer 20 formed on one side of the pulp material 10. As described above, the pulp material 10 has been infiltrated into the pulp material 10 by immersing the pulp material 10 in the sugar composition or by applying the sugar composition to the pulp material 10. The surface layer 20 is a layer formed on the pulp material 10 by the dipping process or the coating process, and includes a sugar component. That is, the surface layer 20 is a layer that does not include the pulp material and includes a sugar component. In addition, the surface layer 20 may be formed so that the one side whole surface of the pulp material 10 may be covered, and may be formed so that the one part surface of one side may be covered.

  The thickness of the surface layer is preferably 1% to 30%, more preferably 5% to 20%, and even more preferably 10% to 15% with respect to the thickness of the pulp material. By appropriately adjusting the thickness of the surface layer, it is possible to obtain a speaker diaphragm that is remarkably excellent in both Young's modulus and internal loss (tan δ). The surface layer can be satisfactorily formed by impregnating the pulp material with the sugar composition by application (preferably application by spraying). Moreover, if the sugar composition is applied using a spray, a large amount of sugar can be introduced into the pulp material while the surface layer is well formed, and the effect of the present invention becomes more remarkable.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further more concretely, this invention is not limited by these Examples. Unless otherwise indicated, parts and percentages in the examples are based on weight.

[Example 1]
(Production of pulp material)
To 300 parts by weight of water, 95 parts by weight of UKP (freeness: 500 cc), 5 parts by weight of cellulose nanofiber (manufactured by Chuetsu Pulp Co., Ltd., bamboo, fiber diameter: about 100 nm) and a sizing agent are added, and pulp is added. A composition was prepared. Paper production of the pulp composition gave a flat pulp material (thickness: 0.45 mm).
(Preparation of sugar composition)
An aqueous solution (concentration: 10% by weight) of fructose (manufactured by Nissin Sugar Co., Ltd.) was prepared and used as a sugar composition.
(Preparation of speaker diaphragm)
The sugar composition was spray-coated on the pulp material. The spray application amount was adjusted so that fructose was 20 parts by weight with respect to 100 parts by weight of the pulp material. Thereafter, the sugar composition was dried to obtain a speaker diaphragm (thickness: 0.51 mm).

[Comparative Example 1]
A pulp composition was prepared by adding 100 parts by weight of UKP (freeness: 500 cc) and sizing agent to 300 parts by weight of water. The pulp composition was paper-made to obtain a flat speaker diaphragm (thickness: 0.6 mm).

[Comparative Example 2]
(Production of pulp material)
A pulp composition was prepared by adding 100 parts by weight of UKP (freeness: 500 cc) and sizing agent to 300 parts by weight of water. Paper production of the pulp composition gave a flat pulp material (thickness: 0.6 mm).
(Preparation of sugar composition)
An aqueous solution (concentration: 10% by weight) of fructose (manufactured by Nissin Sugar Co., Ltd.) was prepared and used as a sugar composition.
(Preparation of speaker diaphragm)
The sugar composition was spray-coated on the pulp material. The spray application amount was adjusted so that fructose was 20 parts by weight with respect to 100 parts by weight of the pulp material. Thereafter, the sugar composition was dried to obtain a speaker diaphragm (thickness: 0.66 mm).

[Comparative Example 3]
To 300 parts by weight of water, 95 parts by weight of UKP (freeness: 500 cc), 5 parts by weight of cellulose nanofiber (manufactured by Chuetsu Pulp Co., Ltd., bamboo, fiber diameter: about 100 nm) and a sizing agent are added, and pulp is added. A composition was prepared. The pulp composition was paper-made to obtain a flat speaker diaphragm (thickness: 0.45 mm).

[Reference Example 1]
A pulp composition was prepared by adding 100 parts by weight of cocoon-derived pulp (freeness: 220 cc) and sizing agent to 300 parts by weight of water. The pulp composition was paper-made to obtain a flat speaker diaphragm (thickness: 0.47 mm).

[Reference Example 2]
(Production of pulp material)
A pulp composition was prepared by adding 100 parts by weight of cocoon-derived pulp (freeness: 220 cc) and sizing agent to 300 parts by weight of water. Paper production of the pulp composition gave a flat pulp material (thickness: 0.47 mm).
(Preparation of sugar composition)
An aqueous solution (concentration: 10% by weight) of fructose (manufactured by Nissin Sugar Co., Ltd.) was prepared and used as a sugar composition.
(Preparation of speaker diaphragm)
The sugar composition was spray-coated on the pulp material. The spray application amount was adjusted so that fructose was 20 parts by weight with respect to 100 parts by weight of the pulp material. Thereafter, the sugar composition was dried to obtain a speaker diaphragm (thickness: 0.54 mm).

[Reference Example 3]
(Production of pulp material)
A pulp material was produced in the same manner as in Reference Example 2.
(Preparation of sugar composition)
An aqueous solution (concentration: 10%) of fructose (Nisshin Sugar Co., Ltd.) was prepared and used as a sugar composition.
(Preparation of speaker diaphragm)
The pulp material was immersed in the sugar composition. The immersion time was 1 hour. Thereafter, the pulp material impregnated with the sugar composition was pulled up, and the sugar composition was dried to obtain a speaker diaphragm (thickness: 0.53 mm).

[Reference Example 4]
(Production of pulp material)
A pulp material was produced in the same manner as in Reference Example 2.
(Preparation of sugar composition)
A methanol solution (concentration: 1%) of fructose (Nisshin Sugar Co., Ltd.) was prepared and used as a sugar composition.
(Preparation of speaker diaphragm)
The pulp material was immersed in the sugar composition. The immersion time was 1 hour. Thereafter, the pulp material impregnated with the sugar composition was pulled up, and the sugar composition was dried to obtain a speaker diaphragm (thickness: 0.50 mm).

<Evaluation>
1. Measurement of Young's modulus and internal loss (tan δ) The Young's modulus and internal loss (tan δ) of the obtained speaker diaphragm were measured by the vibration lead method (cantilever beam, resonance method). Specifically, five test pieces each having a size of 40 mm × 15 mm were cut out from the flat plates produced under the same conditions as the speaker diaphragms obtained in the examples and comparative examples, and the Young's modulus at 23 ° C. for each test piece. The internal loss (tan δ) was measured. In the table, an average value of five test pieces is shown.

2. Thickness measurement Five test pieces each having a size of 40 mm × 15 mm were cut out from the flat plates produced under the same conditions as the speaker diaphragms obtained in Examples and Comparative Examples. Using a dial thickness gauge, the thickness of 4 points (that is, 4 points × 5 pieces, 20 points in total) was measured for each piece, and the average value was obtained.

3. Frequency characteristics Speakers were produced using the speaker diaphragms obtained in Example 1 and Comparative Example 1, and the sound pressure frequency characteristics of the speakers were measured. The results are shown in FIG.

  As apparent from Table 1, the speaker diaphragm of the present invention is excellent in both Young's modulus and internal loss (tan δ). Moreover, it is confirmed from FIG. 2 that the peak dip is suppressed in the frequency characteristics of the speaker manufactured using the speaker diaphragm of the present invention.

  Reference examples 2 and 3 show the difference in the effect of the sugar impregnation method. As is clear from Reference Examples 2 and 3, a speaker diaphragm excellent in Young's modulus and internal loss (tan δ) can be obtained by sugar impregnation by spray coating. In the reference example, it is considered that a speaker diaphragm having a higher Young's modulus can be obtained by further containing cellulose nanofibers in the pulp material.

  Reference examples 3 and 4 show the difference in the effect of the sugar composition on the solvent. As is clear from Reference Examples 3 and 4, the balance between Young's modulus and internal loss (tan δ) can be adjusted by changing the solvent of the sugar composition.

10 Pulp material 20 Surface layer 100 Speaker diaphragm

Claims (8)

Pulp material containing cellulose nanofibers;
A sugar component impregnated in at least a part of the pulp material,
Speaker diaphragm.   The speaker diaphragm according to claim 1, wherein the sugar component is impregnated only in a part of the pulp material. The pulp material further includes a pulp component other than the cellulose nanofiber,
The speaker diaphragm according to claim 1 or 2, wherein a content ratio of the cellulose nanofiber is 1 to 50 parts by weight with respect to 100 parts by weight of a pulp component other than the cellulose nanofiber.   The speaker diaphragm according to any one of claims 1 to 3, wherein the cellulose nanofibers are obtained from cellulose derived from bamboo.   The speaker diaphragm according to any one of claims 1 to 4, wherein the sugar component is a monosaccharide or a disaccharide.   The speaker diaphragm according to any one of claims 1 to 5, wherein a content ratio of the sugar component is 5 to 50 parts by weight with respect to 100 parts by weight of the pulp material. Forming a pulp material with a pulp composition comprising cellulose nanofibers; and
Impregnating the pulp material with a sugar composition containing a sugar component;
The manufacturing method of the speaker diaphragm in any one of Claim 1 to 6. Forming a pulp material with a pulp composition comprising cellulose nanofibers; and
Applying a sugar composition containing a sugar component to the pulp material by a coating method using a spray,
The manufacturing method of the speaker diaphragm of Claim 2.