JPH0787592A - Speaker cone and its manufacture - Google Patents

Abstract

PURPOSE:To maintain a shape better than the one formed by a paper milling method, to reduce the irregularity of thickness and the variance of weight between products and to hardly change internal loss because of the change of a manufacture condition, post-processing, etc. CONSTITUTION:A sheet consists of acrylic synthetic fibers provided with many elongated gaps in a longitudinal direction inside. At least a part of fibers existing at the surface of the sheet are divided into microfibers, undivided acrylic synthetic fibers mostly exist inside the sheet and a layered product consisting of a sheet A obtained by integrating these fibers into one body by mutually confounding and a sheet B consisting of carbon fibers is formed in the shape of a cone. The speaker cone is manufactured by forming the layered product consisting of the sheets A and B into the shape of the cone at 100-250 deg.C under 0.5-30kg/cm<2>.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a speaker cone made of a new material and a method for manufacturing the speaker cone.

[0002]

2. Description of the Related Art Conventional materials for speaker cones include natural wood pulp, synthetic pulp made of synthetic fiber or synthetic resin, natural fiber, synthetic fiber, carbon fiber, glass fiber, or synthetic resin (eg polypropylene) film. There are various materials, and speaker cones that make the best use of the characteristics of each material are manufactured.

A speaker cone made from natural wood pulp is prepared as a papermaking raw material by adding various additives such as fine carbon powder and resin to the pulp which has been disintegrated and beaten, if necessary. This raw material is manufactured into a speaker cone shape by a papermaking mold, and is further put into a molding die and heated and pressed.

In this manufacturing method, the steps up to the preparation of raw materials are long and complicated, and various additives, such as carbon fine powder and resin, are usually added, and the scattering of these additives has a significant adverse effect on the working environment. Is giving. In addition, wastewater and waste containing these additives cause environmental pollution. Further, as described above, since the speaker cone is first made by the papermaking mold, unevenness in thickness is likely to occur in the speaker cone obtained by molding, and the weight of the speaker cone varies among products. It is easy to do and is a problem in quality control. How to reduce such unevenness in thickness and variation in weight is an important point in the speaker cone papermaking process, but at present, it has not been sufficiently improved.

As one of the methods for solving this problem, a speaker cone raw material is made into paper and processed into a sheet in advance, and a mold is used to heat and press the sheet to form a speaker cone. A method can be considered. In this method, the stretching force acts on the sheet because the speaker cone is three-dimensional, but the sheet obtained by papermaking cannot fully respond to this stretching force, and the sheet is partially cut or stretched. You will be blown away.

It is preferable to use long fibers in order to give the sheet a strength that can cope with the stretching force, but the fiber length that can be used when producing a sheet by the papermaking method is 1 to 5 mm, and 5 mm or more. In particular, it was very difficult to produce a uniform sheet by a papermaking method from long fibers of 10 mm or more. Therefore, it is extremely difficult to mold a speaker cone by a method of heating and pressurizing a sheet obtained by papermaking using the mold as described above.

Further, when a synthetic resin such as polypropylene is used as a raw material, pellets of the raw material resin are formed into a film and then vacuum-formed, and then plasma is added in order to improve the adhesion between the speaker cone body and the edge portion. It is manufactured through processes such as treatment, flame treatment, and primer coating. As described above, when a synthetic resin such as polypropylene is used as the raw material, the work up to the paper making process is slightly simplified as compared with the case where the natural wood pulp or the synthetic pulp is used as the raw material. ,
Complex processes such as flame treatment and primer application are required.

Conventionally, a speaker cone made of pulp made of synthetic fiber is a cone made of synthetic pulp made of acrylic synthetic fiber having a lot of elongated voids inside the fiber along its length. A speaker cone made of paper is disclosed in Japanese Patent Application Laid-Open No. 3-154600, and a speaker made of a vibrating plate made by mixing and mixing wood pulp and porous acrylic fiber and making paper from the mixed pulp is disclosed. No. 57-196694.

In the case of manufacturing a speaker cone from the synthetic pulp described in JP-A-3-154600,
Wrinkles that occur when molding into speaker cones are less than in natural pulp, but because the dispersibility of this synthetic pulp in water is poor in the papermaking process, the formation of fiber lumps cannot be avoided, and the resulting product is obtained. The thickness unevenness and weight variation are very large. Further, the papermaking speed is slower than that of natural pulp, and the productivity is extremely low.

On the other hand, when the speaker cone is manufactured from the mixture of the porous acrylic fiber pulp and the wood pulp described in Japanese Patent Laid-Open No. 57-196694, the speaker cone is manufactured from the natural wood pulp. It has the same problem as the case. The internal loss (tan δ), which is one of the acoustic characteristics of these conventional speaker cones, is greatly affected by changes in the manufacturing conditions, post-processing such as resin processing of the speaker cone and laminating processing in which a metal foil is attached to the speaker cone. Therefore, there is a drawback that a large change occurs in the acoustic characteristics. Further, when the acoustic characteristics are changed by mixing fibers having a high strength and a high elastic modulus such as carbon fibers, inorganic fibers or aromatic polyamide fibers, the internal loss changes greatly, so that the ideal acoustic characteristics are obtained. I couldn't get a speaker cone.

[0011]

SUMMARY OF THE INVENTION The present invention solves the above problems in the prior art, simplifies the manufacturing process of the speaker cone, improves the working environment, further reduces the generation of waste, and reduces the speaker cone. (EN) A speaker cone of stable quality with less thickness unevenness and weight variation among products, and a speaker cone that does not change internal loss that occurs when improving acoustic characteristics due to post-processing and mixing of other fibers, and a manufacturing method thereof. It is intended to be provided.

[0012]

The speaker cone of the present invention is made of acrylic synthetic fiber having a large number of elongated voids extending in the lengthwise direction, and the cross-sectional shape of the voids is not specified. At least a part of the fibers present on the surface of the sheet is divided into fine fibers, and most of the undivided acrylic synthetic fibers are present inside the sheet. A laminated body of a sheet A (hereinafter, referred to as sheet A) in which the fibers of (1) are integrated by interlacing with each other and a sheet B (hereinafter, referred to as sheet B) made of carbon fibers are formed into a cone shape. And the speaker cone.

In the method for manufacturing a speaker cone according to the present invention, the laminated body of the sheet A and the sheet B is heated at a temperature of 100.
It is a method for manufacturing a speaker cone, which is characterized in that it is formed into a cone shape at ˜250 ° C. and a pressure of 0.5 to 30 kg / cm ² . The acrylic synthetic fiber present on the surface of the sheet A (meaning the front side and / or the back side of the sheet A) is
At least a part of it must be divided into a number of finer fine fibers over the entire length of the fiber,
There may be fibers that are partially divided in the length direction and also fibers that are not divided. However, most of the acrylic synthetic fibers present on the surface of the sheet A are preferably divided, and more preferably all the fibers are divided. If many undivided fibers are present on the surface of the sheet A, the entanglement of the fibers becomes insufficient, and the tensile strength and tear strength of the sheet A are reduced.

The fibers existing on the surface of the sheet A are intertwined with each other to form a fiber layer on the surface of the sheet A. Most of the acrylic synthetic fibers present inside the sheet A sandwiched between the fiber layers on the surface of the sheet A are undivided fibers, but there may be partially divided fibers. Although fibers may be present, it is preferred that all fibers are undivided and these fibers are intertwined with each other to form the intermediate fiber layer of sheet A. Further, the fibers existing in the fiber layer on the surface and the fibers existing in the intermediate fiber layer are intertwined with each other and integrated to form the sheet A.

The intermediate fiber layer made of undivided acrylic synthetic fibers existing inside the sheet A affects the internal loss which is one of the acoustic characteristics of the speaker cone, and due to the unique fiber structure of this fiber. It produces a characteristic effect of significantly reducing the change in internal loss due to changes in the manufacturing conditions of the speaker cone or post-processing of the speaker cone.

An electron micrograph (4,000 times) of a cross section of the undivided acrylic synthetic fiber is shown in FIG. 1, and an electron micrograph of a longitudinal section (4,000 times) is shown in FIG. In FIG. 1, a black portion a is a cross section of the void, and the shape thereof is various, such as a substantially circular shape, a flat shape, and a shape in which its edge is repeatedly bent, and has a large cross-sectional area. It can be seen that a number of elongated voids with irregular and non-uniform cross-sections are irregularly present in the fibers, small and non-constant.

In FIG. 2, it can be seen that the black portion b is also the void, and each void extends substantially parallel to the length direction of the fiber. The acrylic synthetic fiber having the above-mentioned special fiber structure has a peculiar property of dividing into a plurality of finer fine fibers along the length direction of the fiber by applying an external force to the fiber. To facilitate this division, the length of the aforementioned elongated void is 60.
It is preferably at least μm.

Further, in the elongated void, adjacent ones may be partially connected by a hole. Further, the number of the elongated voids in one cross section of the fiber is preferably 100 or more in order to facilitate the division into the fine fibers by the above-mentioned external force. This acrylic synthetic fiber is manufactured from an acrylic polymer as follows.

The acrylic polymer is 50% by weight (hereinafter,
"%" Means "% by weight" unless otherwise specified) or more acrylonitrile units (hereinafter abbreviated as "AN").
And a polymer of another monomer copolymerizable with AN, or a mixed polymer obtained by mixing these polymers. When AN is less than 50%, the thermal characteristics of the acrylic polymer, which are inherently non-melting and thermoplastic, are lost, and the laminate of sheet A and sheet B is placed in a mold and heated and It becomes difficult to maintain the cone shape when pressure is applied to form the cone shape. There is no upper limit to the content of AN,
It may be a 100% N polymer. Further, even when the acrylic polymer is a mixture, the content of AN needs to be 50% or more based on the weight of the mixed polymer.

The monomer copolymerizable with AN is conventionally known, for example, acrylic acid, methacrylic acid and its esters (methyl acrylate, ethyl acrylate, methyl methacrylate, ethyl methacrylate, etc.), vinyl acetate, Examples thereof include vinyl chloride, vinylidene chloride, acrylamide, methacrylamide, methacrylonitrile, allylsulfonic acid, methallylsulfonic acid, styrenesulfonic acid, vinylpyridine, N, N-dimethylaminoethylmethacrylate.

The above acrylic polymer and polyalkylene glycol are added to a conventionally known solvent for the acrylic polymer, for example, dimethylformamide, dimethylacetamide, dimethylsulfoxide, a concentrated aqueous solution of rhodane salt,
A spinning dope is prepared by dissolving it in a solvent such as a concentrated aqueous zinc chloride solution or an aqueous nitric acid solution. The concentration of the acrylic polymer in the spinning dope varies depending on the solvent, but is generally 10 to 30%.
Is preferred.

The addition of this polyalkylene glycol is an important requirement for forming the aforementioned elongated voids in the acrylic synthetic fiber. This polyalkylene glycol is
A random type copolymer or a block type copolymer in which ethylene oxide and propylene oxide are copolymerized in a weight ratio of 80:20 to 20:80, and the number average molecular weight thereof is 5,000 to 50. 1,000, preferably 6,000 to 20,000.

When the number average molecular weight is less than 5,000, elongated voids continuously extending in the longitudinal direction of the fiber are not formed, and the porous fiber has very fine almost spherical voids. On the other hand, if the number average molecular weight is more than 50,000, the fibers will have huge streak-like cavities, and the fibers will have at most several tens of cavities in the cross section of the fibers. Such fibers are difficult to be divided into fine fibers by an external force, and are not suitable for the speaker cone fiber of the present invention. In order to obtain a fiber having a long and narrow void extending in the length direction of the fiber and having an unspecified cross-sectional shape in a cross section, the number average molecular weight is 10,000 to
Those of 20,000 are particularly preferred.

Further, the spinning dope prepared by dissolving the polyalkylene glycol is aged for at least 4 hours. The maturing of this spinning dope is a necessary condition for obtaining an acrylic synthetic fiber having a large number of elongated voids continuous along the length direction of the fiber. Here, the aging means that the spinning stock solution prepared by dissolving the acrylic polymer and the polyalkylene glycol is vigorously stirred or vibrated without being allowed to stand, for example, being left still or being gently fed. That is.

Although it is not clear why the aforesaid elongated voids are formed by aging the spinning dope containing polyalkylene glycol, it is presumed as follows. That is, agglomeration of polyalkylene glycol occurs due to aging of the spinning dope, and when the spinning dope is spun through the tube through the pores of the spinneret into its coagulating medium, a shearing force acts on the spinning dope. Fine lines of polyalkylene glycol are formed. And
It is considered that due to the difference in the coagulation characteristics of the two, that is, the acrylic polymer coagulates and the polyalkylene glycol does not coagulate, phase-separation of both polymers causes voids having the above-mentioned complicated shape. The aging time may be longer if it is 4 hours or more, but it is 4 to 10
It is preferably time.

The amount of polyalkylene glycol added is 5 to 20%, preferably 10 to 1 based on the acrylic polymer.
5%. If the added amount is less than 5%, the above-mentioned elongated voids are reduced, and if it exceeds 20%, the number becomes too large, and the fibers are divided into finer fine fibers in the fiber manufacturing process, and stable spinning is possible. It causes problems such as disappearance. When the addition amount is 10 to 15%, the number of the elongated voids and the stability of spinning are most balanced, which is preferable.

The above spinning dope is extruded through the spinneret into the coagulation medium of the spinning dope to form a coagulated filament body, and the coagulated filament is subjected to various treatments such as washing, drawing, drying and heat treatment, and then in the length direction. An acrylic synthetic fiber having a number of elongated voids extending along the inside is manufactured. The polyalkylene glycol added to the spinning dope is coagulated, washed with water, the spinning method to be eluted from the coagulated filaments in the fiber manufacturing process such as drawing, may be any method such as wet spinning, dry spinning, or dry wet spinning, After spinning, it is preferable to stretch and wash with water in an aqueous medium in order to elute the polyalkylene glycol from the coagulated filament.

The above-mentioned acrylic synthetic fiber is easily divided into a number of finer fine fibers along its length by the action of an external force. Therefore, by utilizing this characteristic, the sheet A for the speaker cone is made of the acrylic synthetic fiber web,
For example, it can be obtained by forming a non-woven fabric by a columnar flow punching process using conventionally known high pressure water. By this treatment, at least a part, preferably the majority, of the acrylic synthetic fibers present on the surface of the non-woven fabric is divided into a number of finer fine fibers along the length direction thereof. At this time, on the surface of this non-woven fabric, there may be some fibers in which the acrylic synthetic fibers are partially divided, and even undivided fibers may exist, but all the fibers present on the surface of the non-woven fabric are divided. Fine fibers are preferred. These fibers are dispersed in one part and spread randomly, in another part they are bundled together and entangled with each other.

On the other hand, most of the fibers existing inside the nonwoven fabric are undivided acrylic synthetic fibers, and in some cases, partially divided fibers and further divided fine fibers may be present. However, it is preferable that all the fibers existing inside the nonwoven fabric are undivided fibers.
By the columnar flow punching treatment of the high pressure water, the fibers existing near the surface of the non-woven fabric and the entanglement of the divided fine fibers progress at the same time, and the fiber layer on the surface of the sheet A is formed. Further, the inner fibers sandwiched between the surface fiber layers are also entangled at the same time to form an inner fiber layer, and further, the fibers forming the surface fiber layer and the inner fiber layer are entangled and integrated, The inventive sheet A for speaker cone is formed.

The degree of division of the acrylic synthetic fiber can be adjusted by changing the magnitude of the external force applied to the fiber, and the dispersion state of the obtained fine fibers and the degree of entanglement between the fibers can be controlled. It can be adjusted by the magnitude of this external force. The length of the fibers forming the sheet A is not particularly limited, and both long fibers and short fibers can be used, but 20 to 150 m in view of shape retention of the speaker cone.
Fibers with a length of m are preferred, and fibers with a length of 30-60 mm are more preferred.

The basis weight of the non-woven fabric varies depending on the intended use environment of the speaker cone, acoustic characteristics, etc., but is usually 50 to 500 g / m ² , and 100 to 300 g / m ^2.
2 is particularly preferred. The nozzle diameter used for punching the high-pressure water columnar flow is usually 0.05 to 1 mm, preferably 0.1 to 0.5 mm, and the pressure of the high-pressure water columnar flow is 2
0-100 kg / cm ² , preferably 40-80 kg /
cm ² .

A speaker cone comprising the sheet A of the present invention
Is a sheet A made of the acrylic synthetic fiber described above.
It is put in the mold of the shape and molded under the prescribed temperature and pressure.
It is obtained by The temperature at this time is 100-250
℃, preferably 150-200 ℃, the pressure is 0.5
~ 30 kg / cm², Preferably 1 to 10 kg / c
m ²Molding time is 1 to 60 seconds, preferably 2 to 10 seconds
is there.

By molding under the above conditions, the fibers forming the fiber layer on at least one surface of the speaker cone are firmly fixed by being pressed against each other by heat and pressure. At this time, by increasing both the temperature and the pressure within the above range, a speaker cone in which some of the fibers on the surface of the fiber layer are fused can be obtained. If the molding temperature exceeds 250 ° C., the acrylic synthetic fibers will be denatured or decomposed to make molding difficult. If the pressure exceeds 30 kg / cm ² , the fibers on each side of the sheet A will be severely fused and molding will be difficult. Becomes Also, the molding temperature is less than 100 ° C and the pressure is 0.5.
If it is less than kg / cm ² , the shape retention of the speaker cone is deteriorated, and the fused portion of the fiber is not formed on the surface of the sheet A.

By appropriately adjusting these conditions within the above range, it is possible to manufacture speaker cones having various characteristics. Further, the design of this mold can be appropriately changed according to the shape of the target speaker cone and the like. The carbon fiber forming the sheet B is a fiber produced from acrylic synthetic fiber, cellulosic fiber, petroleum or coal pitch fiber, and its length is not particularly limited, and both long fiber and short fiber are used. can do.

The sheet B is preferably a non-woven fabric in view of the ease of producing the sheet B and the laminate of the sheet B and the sheet A, the ease of forming the speaker cone, the uniformity thereof and the like.
The basis weight of the sheet B is usually 10 to 300 g / cm ² , and preferably 20 to 100 g / cm ² , although it varies depending on the purpose of improving the shape retention characteristics, acoustic characteristics and the like. The proportion of the sheet B in the speaker cone is 5% to 50%, preferably 10 to 30% by weight.

The carbon fiber sheet can increase the speed of sound with almost no change in the internal loss of the speaker cone, and can improve the Young's modulus. For this reason, the speaker cone of the present invention in which the carbon fiber sheets are laminated is an ideal speaker cone having a more transparent and nearly natural sound quality. The laminate of the sheet A and the sheet B is a laminate of two or more layers in which the sheets A and B are alternately laminated. This laminate is not particularly limited as long as it has two or more layers, but a laminate of three layers in which both sides of the sheet B are sandwiched by the sheets A is preferable.

A speaker cone can be manufactured by placing this laminated body in a mold having a predetermined shape and molding it into a cone shape at a predetermined temperature and pressure. Undivided acrylic synthetic fibers are present inside the sheet A that has become the speaker cone in the thickness direction. The undivided fibers are entangled with each other to form an intermediate fiber layer, and at the same time, entangled with the divided fine fibers forming the surface fiber layer,
All fibers are bonded together.

The undivided acrylic synthetic fiber present inside the sheet A is an acrylic synthetic fiber having a structure which is almost the same as that before the molding, even after being molded into a speaker cone. The undivided fibers and the divided fine fibers existing inside the thickness direction are in close contact with each other and are simply strongly pressed. Furthermore, there are many spaces between the fibers.

When the nonwoven fabric made of the above-mentioned acrylic synthetic fiber is manufactured as the sheet A for the speaker cone in the present invention, other fibers such as natural wood pulp, carbon fiber, aromatic polyamide fiber or mineral fiber are used. It can be mixed in an amount of 10% or less depending on the characteristics required for the speaker cone. It is also possible to add additives such as carbon powder, resin powder, colorants, and ceramics. Further, the molded speaker cone is subjected to resin impregnation or coating, metal deposition, coloring, or the like to give various characteristics to the speaker cone characteristics and design.

[0040]

[Regarding Shape Retention] The sheet A of the present invention has a special fiber structure of acrylic synthetic fibers. The sheet itself has a special structure. It is characterized in that the physical properties such as the tensile strength of the sheet A are significantly improved due to factors such as being a uniform sheet using long fibers.

The structural and physical factors of the above sheet A are combined with the inherent properties of the acrylic synthetic fiber, that is, the acrylic synthetic fiber is a non-melting type but has a thermal property of being thermoplastic. Thus, when the sheet A is molded into a speaker cone with a mold, the sheet A can sufficiently cope with the stretching force acting on the sheet A. Therefore, when the sheet A is molded into a speaker cone having a three-dimensional shape, the sheet A can be molded into a uniform speaker cone without breakage or distortion.

Further, the speaker cone formed of the sheet A has a fused portion of the fibers existing on the surface of the sheet A on at least one surface thereof, and the undivided acrylic synthetic fiber is inside thereof. Existing. This fused portion greatly contributes to the shape retention of the speaker cone, undivided acrylic synthetic fibers are present inside the cone-shaped sheet A, and many spaces are included between the fibers. However, it is a major factor in firmly maintaining the speaker cone shape.

Also in a speaker cone having high-strength or high-modulus fibers such as carbon fiber inside, the fused portion existing on the surface thereof is a major factor for firmly holding the shape, as described above. is there. The fused part of the above-mentioned acrylic synthetic fiber is a laminated body of the sheet A and the sheet B at a temperature of 100 to 250 ° C. and a pressure of 0.5 to 30 kg / cm ^2.
It can be formed on at least one surface of the speaker cone by molding. [Acoustic Characteristics] The speaker cone of the present invention is formed by a laminate of a sheet A and a sheet B made of a special acrylic synthetic fiber, and this sheet A is formed into a speaker cone as described above. Even after being formed, it contains an acrylic synthetic fiber having a structure (having a large number of elongated voids extending in the length direction) in the inside in the thickness direction which is almost the same as that before forming.

On the surface of the speaker cone, the fine fibers obtained by dividing the acrylic synthetic fibers are dispersed and spread in a certain portion, and are present in a bundled state in another portion. . The synergistic effect of these things and the thermal characteristics originally possessed by the acrylic synthetic fiber causes the following effects on the characteristics required for the speaker cone, especially the internal loss. .

That is, the internal loss of the speaker cone using natural pulp changes depending on its molding temperature and pressure, changes with resin processing and metal laminate such as aluminum, and also changes with fibers mixed with the natural pulp. However, the speaker cone of the present invention has a value equivalent to the internal loss of idealized natural pulp, and this internal loss is hardly changed by these processings.

The size and dispersion state of the space existing inside the speaker cone of the present invention can be adjusted by appropriately changing the pressure and temperature during molding. From this, in the speaker cone of the present invention, for the sound velocity which is another characteristic of the speaker cone, the molding pressure,
It can be freely changed by changing processing conditions such as temperature or metal laminating.

With the carbon fiber sheet B, the sound velocity can be increased with almost no change in the internal loss of the speaker cone, and the Young's modulus can be improved. For this reason, the speaker cone of the present invention in which the carbon fiber sheets are laminated is an ideal speaker cone having a more transparent and nearly natural sound quality. Furthermore, speaker cones having different tones can be easily manufactured.

[0048]

EXAMPLES The present invention will be specifically described below with reference to examples. First, an acrylic synthetic fiber forming the sheet A for a speaker cone was manufactured as follows. Dimethylformamide has a composition of AN 95.0%, methyl acrylate 4.5%, and sodium methallyl sulfonate 0.5%.
And a block type polyether of polyethylene oxide-polypropylene oxide-polyethylene oxide (the number average molecular weight is 10,000, the polymerization ratio is polyethylene oxide: polyethylene oxide = 70: 3).
0) and were dissolved to prepare a spinning dope containing 23% of the copolymer and 2.3% of the block type polyether.

After leaving this spinning dope for 6 hours,
Through a spinneret having pores with a diameter of 0.08 mm, a temperature of 35 ° C., 75% of dimethylformamide and 25% of water.
It was extruded into the aqueous coagulation bath containing it to produce a coagulated filament. Next, this coagulated filament was washed with water, drawn 10 times in boiling water, dried in hot air at 80 ° C., crimped, and then cut into 76 mm to produce an acrylic synthetic fiber.

The single fineness of this fiber was 2d, the tensile strength was 3.2 g / d, and the tensile elongation was 32%. Electron micrographs showing the state of the cross section and the longitudinal section of this fiber are shown in FIG. 1 and FIG. 2 (4,000 times). As can be seen from these figures, the fiber had a large number of elongated voids extending along its length.

This fiber was formed into three webs having a basis weight of 100, 120 and 200 g / m ² using a spinning card machine. These webs were placed on a wire mesh moving at a speed of 4 m / min, and nozzles having pores with a diameter of 0.1 mm were arranged in a row at 0.8 mm intervals to form a columnar flow treatment device at 60 kg / cm ² . Treated with high pressure water. After repeating this treatment 10 times alternately on the front and back surfaces of the web, the obtained nonwoven fabric (sheet A) was dried in hot air at 80 ° C.

In the sheet produced by the above method, almost all of the fibers existing on the front surface and the back surface of the sheet are divided into a large number of finer fine fibers, the fine fibers are dispersed and spread in one portion, and in another portion. While accumulating in a bundle, the undivided acrylic synthetic fibers are present between the front surface and the back surface of the sheet, and these fibers are entangled with each other, and the sheet A is entangled as a whole with the sheet A. All the fibers to be formed were integrated.

Three kinds of sheets A thus obtained
Was used to mold various speaker cones.

[0054]

Example 1 A three-layer laminate in which a non-woven fabric made of carbon fiber and having a basis weight of 50 g / m ² is sandwiched between the sheets having a basis weight of 100 g / m ² is placed in a mold for producing a speaker cone, and the temperature is set to 180. A large number of speaker cones were manufactured by molding at a temperature of 2 ° C. and a pressure of 2 kg / cm ² for 5 seconds.

Undivided acrylic synthetic fibers exist inside the speaker cone in the thickness direction, and these undivided acrylic synthetic fibers are entangled with each other and also with the divided fine filaments. The undivided acrylic synthetic fibers and the divided fine fibers existing inside these thickness directions are in close contact with each other. That is, even after being molded into a speaker cone, an acrylic synthetic fiber having a large number of elongated elongated voids extending in the length direction is present inside the thickness direction of the speaker cone, which structure is almost the same as before molding. . Further, the carbon fiber was sandwiched between the acrylic synthetic fiber sheets and firmly fixed.

Further, no abnormalities such as deformation and breakage of the laminate were observed during molding, and the moldability was extremely good. The variation in weight between the speaker cones was within ± 4%. Table 1 shows the characteristics of the speaker cones (No. 1-3). Table 1
As can be seen from the above, the sound velocity of this speaker cone is greatly improved with almost no change in internal loss.

[0057]

Example 2 After coating 100H clear (trade name, manufactured by Ron Chemical Co., Ltd.) as a modified silica resin solution containing 20% by weight of solid content on the entire surface of the No. 1 speaker cone manufactured in Example 1. Then, it was naturally dried to manufacture a speaker cone containing ceramic. The variation in weight among the speaker cones was within ± 4%.

Table 2 shows the characteristics of each speaker cone (No. 4 to 6). As can be seen from Table 2, the sound velocity and the Young's modulus of the speaker cone have been greatly improved by processing the resin, but the internal loss hardly changes, and it is similar to the speaker cone made of natural pulp.

[0059]

Example 3 A large number of speaker cones were manufactured by laminating an aluminum foil having a thickness of 50 μm with an adhesive on the No. 1 speaker cone manufactured in Example 1. The variation in weight between the obtained speaker cones was within ± 4%. Table 3 shows the characteristics of each speaker cone (No. 7 to 9).

As can be seen from Table 3, this speaker cone has a significantly improved sound velocity and Young's modulus by laminating aluminum foil, but the internal loss hardly changes by this processing and the speaker is made of natural pulp. Same as corn.

[0061]

Comparative Example 1 A speaker cone was manufactured from natural pulp as follows. After swelling the raw material pulp, the raw material is prepared through steps such as dissociation and beating, and "Peroza WS" (rosin resin) manufactured by Modern Chemical Industry Co., Ltd. is added to this raw material to adjust pH and concentration. After that, paper making into a speaker cone shape with a wire mesh, dehydration, press processing,
The slope of the speaker cone was formed. After cutting this slope portion, finishing processing was performed to manufacture a large number of speaker cones. The variation in the weight of each speaker cone was ± 10%.

Table 4 shows an example of these speaker cones (N
The characteristics of o.10) are shown.

[0063]

[Table 1]

[0064]

[Table 2]

[0065]

[Table 3]

[0066]

[Table 4]

[0067]

As described above, in the speaker cone of the present invention, the laminated body of the sheet A having the special structure and the carbon fiber sheet formed of the acrylic synthetic fiber having the special structure is provided at a specific temperature. It is molded by pressure and has the following features. 1. The shape retention property is extremely good as compared with that formed by the sheet obtained by the papermaking method.

2. It becomes possible to manufacture a speaker cone without performing a papermaking process, and it is possible to significantly improve the working environment at the speaker cone manufacturing site and suppress the generation of waste. 3. Since it is possible to reduce unevenness in the thickness of the speaker cone and variation in weight between products, it is possible to provide a speaker cone with stable quality.

4. When a synthetic resin film is used as a raw material in the prior art, complicated processes such as plasma treatment, flame treatment and primer coating are required after molding,
The speaker cone of the present invention does not require such processing. 5. Since the internal loss of acoustic characteristics hardly changes due to changes in manufacturing conditions, resin processing, metal foil laminating processing, etc., other characteristics such as sound velocity can be spread over a wide range by changing manufacturing conditions and processing conditions. Can be changed in a balanced manner.

6. Since the carbon fiber sheets are laminated, the sound velocity can be increased with almost no change in the internal loss of the speaker cone, and the Young's modulus can be improved. 7. For this reason, the speaker cone of the present invention in which the carbon fiber sheets are laminated is an ideal speaker cone having a more transparent and nearly natural sound quality.

[Brief description of drawings]

FIG. 1 is an electron micrograph (4,000 times) showing a fiber shape in a cross section of an acrylic synthetic fiber constituting a speaker cone of the present invention.

FIG. 2 is an electron micrograph (× 4000) showing a fiber shape in a longitudinal section of an acrylic synthetic fiber that constitutes the speaker cone of the present invention.

Claims (2)

[Claims] 1. A sheet composed of acrylic synthetic fibers having a large number of elongated voids extending in the length direction therein, and the cross-sectional shape of the voids is unspecified, and the surface of the sheet. At least a part of the fibers existing in the sheet is divided into fine fibers, and most of the undivided acrylic synthetic fibers are present inside the sheet, and these fibers are integrated by entanglement with each other. A speaker cone in which a laminate of a sheet A and a sheet B made of carbon fiber is formed into a cone shape. 2. A sheet composed of an acrylic synthetic fiber having a large number of elongated voids extending in the length direction therein, and the cross-sectional shape of the voids is unspecified, and the surface of the sheet. At least a part of the fibers existing in the sheet is divided into fine fibers, and most of the undivided acrylic synthetic fibers are present inside the sheet, and these fibers are integrated by entanglement with each other. The laminated body of the sheet A and the sheet B made of carbon fiber is heated at a temperature of 100 to 250.
A method for manufacturing a speaker cone, which comprises forming a cone at a temperature of 0.5 to 30 kg / cm ² .