JPH0522792A - Supporter for speaker diaphragm - Google Patents

Abstract

PURPOSE:To obtain a supporter for a speaker diaphragm which excels in the acoustic characteristic, the durability, and the fabrication workability. CONSTITUTION:A laminated material contains integrally an autohesive unwoven fabric consisting of polyurethane elastic fibers of 7-30mu average diameters and a polyurethane film. Then the modulus of the laminated material is set under 0.8-4g/cm/g/m<2> with the hardness set under 100mm respectively in a 30% extension state.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a speaker having excellent acoustic characteristics and a support for a speaker diaphragm.

[0002]

2. Description of the Related Art A support for a speaker diaphragm, such as a speaker cone edge or a damper, must maintain the posture of the diaphragm and the voice coil driven by the voice coil correctly and should not adversely affect the vibration. It is required that abnormal vibration such as resonance does not occur and that the propagation of vibration is sufficiently damped. Further, airtightness is required so that air vibrations of different phases are mixed on the front and back of the diaphragm so as not to interfere with each other.

Conventionally, in order to solve such problems, in terms of materials, paper is impregnated with resin, cotton cloth or the like is coated with elastomer, or polyurethane foam is laminated, polyurethane or polystyrene.
Various proposals have been made for polyolefin copolymer elastomers, foams made of a mixture of ethylene / vinyl acetate copolymer and polyethylene, polyurethane films, and the like. Further, the shape thereof is also devised such as being formed into a concentric corrugated cross section.

[0004]

A conventional cotton cloth or the like coated with a polyurethane foam and a laminated polyurethane foam have a large rigidity, a unit weight and a large thickness, and adversely affect the diaphragm. Further, when forming a concentric circular corrugated cross section, there is a problem that the process becomes complicated.

The support of the diaphragm made of foam is
Although the moldability is relatively good, in the case of the open-cell structure, the air on the back side of the diaphragm leaks to the front side through the open-cells, leading to deterioration of sound quality. The rigidity increases and the internal loss decreases. Further, since it has a foam structure, the strength is small, and in order to increase the strength, it is necessary to make it thick or reduce the porosity, and it is preferable to increase the basis weight and bending rigidity in any case. Absent. Further, the polyurethane foam is severely deteriorated with time and cannot withstand long-term use. On the other hand, although the polyurethane film is comparatively small in deterioration, it has a problem that abnormal vibration is liable to occur in a large output and a sufficient sound quality cannot be obtained.

The present invention is intended to provide a support for a diaphragm of a speaker, which is excellent in moldability, has a small bending rigidity and a low basis weight, has a large internal loss, and has excellent acoustic characteristics and durability. is there.

[0007]

The present invention has an average fiber diameter of 7
A self-bonding non-woven fabric made of polyurethane elastic fiber of ~ 30μ and polyurethane film are laminated and integrated.
A speaker diaphragm support having a% modulus of 0.8 to 4 g / cm / g / m ² and a bending resistance of 100 mm or less.

First, as an important point in the present invention, the average fiber diameter of the polyurethane elastic fibers constituting the non-woven fabric is 7 to 7.
It may have to be 30μ, preferably 10-25μ. When the average fiber diameter becomes large, the surface area of the fiber becomes small, so that deterioration over time due to oxidation, hydrolysis, light, etc. becomes small, and the durability becomes excellent. However, as the average fiber diameter increases, the bending rigidity of the fibers increases, and the number of constituent fibers per unit area of the nonwoven fabric decreases. Therefore, the flexural rigidity and the tensile rigidity of the non-woven fabric are increased, and the flexural rigidity when laminated with the polyurethane film is increased. Furthermore, since the number of cross-bonding points between the fibers is reduced, the internal loss is also reduced, and the acoustic characteristics are deteriorated when incorporated in the speaker. On the other hand, when the average fiber diameter becomes smaller, the bending rigidity of the fiber becomes smaller and it becomes softer,
Since the surface area of the fiber becomes large, deterioration of the fiber due to oxidation or light becomes large, resulting in poor durability. Thus, in the present invention, a polyurethane elastic fiber nonwoven fabric having an average fiber diameter of 7 to 30 μ is used in order to balance the acoustic characteristics and the durability.

A self-fusing nonwoven fabric made of polyurethane elastic fibers having an average fiber diameter of 7 to 30 μ is, for example, a thermoplastic polyurethane resin which is melt-extruded and discharged from a spinneret, and at the same time, is ejected from a gas ejection hole or ejection groove adjacent thereto at a high temperature. It can be produced by a so-called melt blown method in which a fine fiber flow is formed by a high-speed gas flow, and while it is still sticky, it is collected in a nonwoven sheet form on a moving wire mesh belt conveyor-like collector. .. Non-woven fabrics having different average fiber diameters and textures can be produced by changing the discharge amount of the polyurethane resin from the spinneret, the temperature and flow velocity of the jetted gas, and the like. Nonwoven fabric has 1 constituent fiber
It is preferable that the particles are not arranged in a direction, but are isotropic particles that are uniformly deposited on the entire surface without directionality. In addition, it is preferable that the non-woven fabric is uniform and does not contain polymer beads caused by defective thinning such as so-called shots.

The unit weight of the nonwoven fabric of the present invention varies depending on the size of the speaker used, allowable input, etc.
300 g / m ^2, preferably in the range of 70~200g / m ^2. When the basis weight becomes large, the tensile rigidity and bending rigidity become large, and the inertial force also becomes large, which adversely affects the vibration of the diaphragm and deteriorates the sound quality. On the other hand, if the fabric weight is too small, the tensile rigidity becomes too small, the posture of the diaphragm cannot be maintained correctly, and the vibration damping effect becomes small, and it is not possible to obtain a sufficient effect. Making non-woven fabrics efficiently becomes difficult.

The thermoplastic polyurethane used for the polyurethane elastic fiber nonwoven fabric of the present invention includes polyester diol obtained by condensation polymerization of low molecular weight diol and dicarboxylic acid, polylactone diol obtained by ring-opening polymerization of lactam, polyoxyalkylene glycol and the like. It is a thermoplastic polyurethane obtained by reacting a polymer glycol having an average molecular weight of 500 to 3,000, an organic diisocyanate, and a low molecular weight compound having two active hydrogen atoms.

The above-mentioned general thermoplastic polyurethane is used for the purpose of the present invention, but when it is used under particularly severe conditions such as car stereo, it has higher durability as follows. It is preferable to use polyurethane. From the viewpoint of the balance between flexibility and durability, the preferred thermoplastic polyurethane has 4 or more carbon atoms, preferably 6 to 12 carbon atoms,
More preferably, aliphatic diols or alicyclic diols having 8 to 12 carbon atoms, such as 3-methyl-1,5-pentanediol, hexanediol, 1,8-octanediol, 1,9-
Nonanediol, 1,10-decanediol, 1,11-undecanediol, 1,12-dodecanediol, 2- or 3-methyl-1,7-heptanediol, 2- or 3-methyl-1,8-octane At least one selected from linear or side chain aliphatic diols or alicyclic diols such as diols and ω, ω'-dihydroxy-1,4-dimethylcyclohexane.
At least one selected from various diols and aliphatic dicarboxylic acids such as succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, dodecanedicarboxylic acid, and esters of these dicarboxylic acids. Polyester diol having an average molecular weight of 600 to 3,000 obtained by reacting a kind of dicarboxylic acid or its ester, and as an organic diisocyanate, for example, phenylene diisocyanate, tolylene diisocyanate, 4,4′-diphenylmethane diisocyanate, 4,
4'-dicyclohexylmethane diisocyanate, cyclohexane diisocyanate, isophorone diisocyanate, xylylene diisocyanate, or other organic diisocyanate mainly composed of aromatic or alicyclic diisocyanate, and optionally selected from aliphatic diisocyanate or diisocyanate having a naphthalene ring A chain extender selected from organic diisocyanates and low molecular weight compounds having two active hydrogen atoms, for example, diols, amino alcohols, hydrazines and diamines. Then, the polymer diol, the organic diisocyanate, and the chain extender are selected at a desired composition ratio and polymerized by a melt polymerization method, a bulk polymerization method, a solution polymerization method, or the like to obtain a thermoplastic polyurethane. In order to obtain a non-woven fabric having good uniformity, the thermoplastic polyurethane has a content of the polymer diol serving as the soft segment of 45 to 75% by weight in the composition at the time of producing the polyurethane.

Polycarbonate polyurethane has high durability such as hydrolysis resistance and oxidation deterioration resistance, but is generally inferior in flexibility, and it is difficult to obtain the one satisfying the performance of the present invention. However, a polycarbonate-based polyurethane having a soft segment of a polycarbonate-based diol containing a diol unit derived from an aliphatic diol having 8 to 12 carbon atoms and a carbonyl unit has relatively high flexibility and can be used in the present invention.

Carbon black may be added to the thermoplastic polyurethane as a colorant prior to melting the polyurethane or prior to spinning to improve photodegradability. The amount of carbon black added to improve the photo-deterioration property of the polyurethane elastic fiber is in the range of 0.05 to 1.5% by weight based on the polyurethane resin. If the added amount is small, a sufficient effect cannot be obtained, and if the added amount is large, the polyurethane elastic fiber becomes hard and the acoustic characteristics are deteriorated.

Further, a hindered phenol compound and / or a benzotriazole compound may be added to the thermoplastic polyurethane prior to melting the polyurethane or prior to spinning. The amount added is in the range of 0.1 to 3% by weight based on the thermoplastic polyurethane. The action of these additives is to positively react the active group of the additive with the dissociated portion and stabilize it, in order to prevent the heat-melted polyurethane from dissociating and causing an undesirable side reaction. At the same time, the effect of suppressing the oxidation or photodegradation that the additive has is also provided. Therefore, when the amount of the additive added is small, the dissociated portion of the polyurethane is sufficiently blocked and cannot be stabilized. Also,
When the addition amount is large, the additive rather causes an undesirable side reaction in the polyurethane, which deteriorates the performance of the polyurethane.

In order to improve the spinnability and spinnability of polyurethane and to form a stable fiber flow, silicone oil or a polyolefin resin such as polyethylene or polypropylene is added to polyurethane at any stage before spinning. May be. Applicable silicone oil is a compound that is inactive to molten polyurethane, does not increase the vapor pressure of the polyurethane melt system, and has a viscosity at 30 ° C in the range of 2 to 150 poise, such as dimethyl. Compounds such as polysiloxane and methylphenylpolysiloxane, and other oils selected from heat-resistant general silicone oils can be added in an amount of 0.05 to 2% by weight based on polyurethane. When a non-elastic resin such as a polyolefin resin is mixed, the resulting nonwoven fabric tends to have a high modulus, so the addition amount is preferably within 10% by weight.

By thus mixing the stabilizer, the silicone oil, etc., the melt blown moldability of polyurethane is improved, and a uniform nonwoven fabric having a stable fiber diameter can be stably produced, which further improves the acoustic characteristics. It will be excellent.

The polyurethane elastic fiber self-fusing nonwoven fabric thus obtained is laminated with a polyurethane film to form a support for the speaker vibrating body of the present invention. That is, since the polyurethane non-woven fabric is composed of elastic fibers with good fiber uniformity, it has low rigidity and high vibration damping effect at the small deformation required for the cone edge of the speaker, but the non-woven fabric is breathable. Therefore, when used alone, there arises a problem that vibrations of opposite phases on the front and back of the diaphragm interfere with each other. Further, it may be fluffed due to abrasion or abrasion, which impairs the beauty appearance of the product, whereas the polyurethane film is impermeable, and fluff due to abrasion or abrasion is used for this purpose. Is so good that it doesn't cause any problems.

The polyurethane used for the polyurethane film may be the same thermoplastic polyurethane as that used for the nonwoven fabric. In this case, the same polyurethane as the nonwoven fabric may be used, or a polyurethane having a different composition may be used. The thickness of the polyurethane film is preferably in the range of 10μ to 50μ. If the thickness of this film is too thick, the rigidity and inertial force are increased, which adversely affects the vibration of the diaphragm.
On the other hand, if the thickness is too thin, the strength will be reduced and it will be easily damaged. The rigidity, moldability, etc. can be adjusted by mixing an appropriate amount of another resin with the resin constituting the polyurethane film.

The polyurethane elastic fiber nonwoven fabric and the polyurethane film can be laminated and integrated by a method such as calendering with an embossing roll or flat roll, and bonding with ultrasonic waves. This integration needs to be performed under the condition that the nonwoven fabric does not become a film. Alternatively, the polyurethane elastic fibers may be directly melt-blown on the polyurethane film to be laminated and integrated.

The sheet thus laminated and integrated has its 30% modulus (stress per unit width at 30% elongation,
The vertical / horizontal average) must be 0.8 to 4 g / cm / g / m ² , and the bending resistance (cantilever method, vertical / horizontal average) must be 100 mm or less. If the modulus is low by 30%, the force to control the posture of the speaker cone or voice coil becomes weak and the reproducibility of the sound deteriorates. On the other hand, if the 30% modulus becomes large or the bending resistance becomes large, the response to the input signal to the speaker becomes poor, and abnormal vibration tends to occur at the time of a large input, which adversely affects the sound quality. Also, these 30%
It is preferable that the modulus and the bending resistance are isotropic with the aspect ratio and the aspect ratio close to 1.

The support for the speaker vibrating body of the present invention thus obtained is flexible, has a large internal loss, is excellent in acoustic characteristics, and is excellent in durability. The durability can be evaluated, for example, by the retention rate of 30% modulus after dry heat treatment at 110 ° C. The support of the present invention has a temperature of 110 ° C.
The retention rate of 30% modulus after dry heat treatment for 1 week at
It is 50% or more, preferably 80% or more, more preferably 90% or more. If the retention rate of 30% modulus is less than 50%, even if the sound quality is initially good, it deteriorates over time during use, making long-term use difficult. Since the polyurethane elastic fiber of the present invention has an average fiber diameter of 7 μm or more, deterioration due to oxidation or hydrolysis from the surface is small, but it is more durable by selecting the above-mentioned polyurethane resin having high deterioration resistance. can do.

Since the support of the speaker diaphragm of the present invention is made of thermoplastic polyurethane, it can be processed into a corrugated shape by press molding or the like to be used for a cone edge or a damper as in the conventional product, and of course, it is not corrugated. It can also be used in a flat shape.

[0024]

EXAMPLES The embodiments of the present invention will now be described with reference to specific examples, but the present invention is not limited to these examples. In the examples, parts and% relate to weight unless otherwise specified.

Example 1 Polyester diol having an average molecular weight of 1500 and consisting of 3-methyl-1,5-pentanediol and adipic acid and a molecular weight of 50
A polyurethane with a nitrogen content in the polymer of 3.8% was obtained, which consisted of less than 0 1,4-butanediol and 4,4′-diphenylmethane diisocyanate.

In the melt-blown device described in JP-A-49-48921, spinning holes having a diameter of 0.3 mm are arranged in a row at a pitch of 1 mm, and 1.2 mm thick slit-shaped gas discharge holes are provided on both sides thereof. Using the above, the above polyurethane and a masterbatch for original wear containing carbon black in the above polyurethane were blended to obtain 0.5% carbon black polyurethane, and this was discharged at a melting temperature of 225 ° C. at 0.30 g / m ² per spinning hole, 0.5kg / cm of heated air at 225 ℃
Melt blown by spraying from a slit-shaped gas discharge hole with a pressure of ² gauge. At this time, the jetted fiber stream was collected on a belt conveyor-like collector of a wire net running 20 cm below the spinning hole, and a basis weight of polyurethane fiber 205 g
A self-melting meltblown nonwoven fabric of / m ² was obtained. When this non-woven fabric was magnified and observed with a scanning electron microscope, the average fiber diameter was 24μ.

The same polyurethane was used as a raw material and was film-formed using a T-die type film forming machine to a thickness of 30 μm.
A polyurethane film of This polyurethane non-woven fabric and polyurethane film are stacked in layers, and the roll surface is supplied to an embossing device that combines a flat roll with an embossing roll with a convex shape of 10% and a flat surface, and the roll temperature is 105 ° C. , Press line pressure 20kg / c
Bonding was performed at m and a processing speed of 20 m / min.

The resulting non-woven film laminate had a basis weight: 2
44 g / m ² , thickness: 0.94 mm, apparent density: 0.26 g / cm ³ ,
Strength (horizontal / horizontal average): 42.3 g / cm / g / m ² , elongation (vertical / horizontal average): 361%, bending resistance (cantilever): 66 mm, 3
0% modulus: It had a mechanical property value of 0.6 g / cm / g / m ² . Also, 110% dry heat treatment 30% after 1 week
The modulus retention was 79%.

Using this, hot press molding and cutting processing were performed to prepare a support (cone edge) for the diaphragm of the speaker having a corrugated cross section, and the support was installed in an actual speaker to examine the acoustic characteristics and the like. As a result, the cone edge of the speaker not only keeps the posture of the diaphragm correct, but also does not adversely affect the vibration and does not cause abnormal vibration such as resonance itself.
Vibration was also effectively damped. Further, it also had a proper airtightness in which air vibrations of different phases were not mixed and interfered with each other on the front and back of the diaphragm. Furthermore, the ability of the cone edge to follow vibrations was particularly good, and the ability to smoothly return to its original shape even after large deformation was outstanding. The practical durability of these performances was also good. A speaker using such a support for a speaker diaphragm has both the above-mentioned excellent acoustic performance and durability.

Example 2 Instead of 3-methyl-1,5-pentanediol, 2-methyl-1,
A polyurethane was obtained under the same conditions as in Example 1 except that a mixture of 8-octanediol and 1,9-nonanediol was used, and melt blown under the same conditions as in Example 1 to obtain a self-melting melt blown nonwoven fabric. .. The average diameter of the fibers constituting this meltblown nonwoven fabric was 25μ as measured by a scanning electron microscope photograph.

Using the same polyurethane as the raw material, T
Film is formed using a die film forming machine and the thickness is
A 30μ polyurethane film was obtained. This polyurethane film and self-melting meltblown non-woven fabric are layered and the roll surface has a square convex shape and the area ratio of that part is
An embossing device combining a 10% embossing roll and a flat roll having a flat surface was used to perform the bonding process under the conditions of a roll temperature of 105 ° C., a press linear pressure of 20 kg / cm and a processing speed of 20 m / min. The resulting non-woven film laminate has a basis weight:
241 g / m ² , thickness: 0.93 mm, apparent density: 0.25 g / cm ³ ,
Strength (horizontal / horizontal average): 43.1 g / cm / g / m ² , elongation (vertical / horizontal average): 331%, bending resistance (cantilever): 64 mm, 3
0% modulus: It had a mechanical property value of 1.5 g / cm / gm ² . Also, 110% dry heat treatment 30% after 1 week
The modulus retention was 91%.

By using this, a cone edge of a speaker having a corrugated cross section was prepared by hot pressing and cutting, and the speaker was attached to an actual speaker diaphragm to examine acoustic characteristics and the like. As a result, the cone edge of the speaker not only keeps the posture of the diaphragm correct, but also does not adversely affect the vibration, does not cause abnormal vibration such as resonance itself, and effectively attenuates the vibration. Met. Further, it also had a proper airtightness in which air vibrations of different phases were not mixed and interfered with each other on the front and back of the diaphragm. Furthermore, the ability of the cone edge to follow vibrations was particularly good, and the ability to smoothly return to its original shape even after large deformation was outstanding. The practical durability of these performances was also good. A speaker using such a support for a speaker diaphragm has both the above-mentioned excellent acoustic performance and durability.

Comparative Example 1 The same polyurethane as in Example 1 was used, and the same meltblown device was used. The thickness of the slit-shaped gas discharge holes was changed to 0.2 mm, and the polymer discharge amount per spinning hole was 0.2.
g / min, polymer melting temperature 250 ° C, heated air temperature 2
At 50 ℃, the pressure is changed to 1.6 kg / cm ² gauge pressure respectively, but other conditions are the same and melt blown,
A self-fusing meltblown nonwoven fabric having a basis weight of 206 g / m ² was obtained. The average fiber diameter of the polyurethane fibers forming this nonwoven fabric was 6.1 μm, which was outside the scope of the present invention.

The same 30 μm thick polyurethane film used in Example 1 was embossed by the same embossing apparatus as in Example 1 under the same embossing conditions. The resulting nonwoven fabric / film laminate has a basis weight: 241 g /
m ² , thickness: 0.97 mm, apparent density: 0.28 g / cm ³ , strength (vertical / horizontal average): 41.1 g / cm / g / m ² , elongation (vertical / horizontal average): 311%, bending resistance (cantilever) : 62mm, 30%
Modulus: It had a mechanical property value of 1.3 g / cm / g / m ² . The 30% modulus retention rate after 1 week of dry heat treatment at 110 ° C was 43%.

With respect to this, the acoustic characteristics as the cone edge of the speaker were examined in the same manner as in Example 1. As a result, the cone edge of the speaker not only keeps the posture of the diaphragm correct, but also itself does not cause abnormal vibration and effectively attenuates the vibration, and there is no problem in acoustic performance. However, among such good performances at the initial stage, the posture retention of the diaphragm and the shape recoverability at the time of large deformation begin to fall after 6 to 9 months of actual use and become unusable after 1 year. It was

Comparative Example 2 Polyurethane having a nitrogen content of 4.3% obtained from exactly the same raw material as in Example 1 was used, and the same meltblown device was used, and the polymer discharge rate per spinning hole was 0.6 g / min. Melt temperature is 220 ° C, heated air temperature is 220 ° C, and its pressure is changed to 0.2 kg / cm ² gauge pressure, but melt blowing is performed under the same other conditions, with a basis weight of 206 g / m ²
A self-melting meltblown nonwoven fabric of was obtained. The average fiber diameter of the polyurethane fibers forming this non-woven fabric was 42 µ, which was outside the scope of the present invention.

The polyurethane film having the same thickness as that used in Example 1 and 30 μm was embossed by the same embossing device as in Example 1 under the same embossing conditions. The resulting nonwoven fabric / film laminate has a basis weight: 241 g /
m ² , thickness: 1.08 mm, apparent density: 0.22 g / cm ³ , strength (vertical width): 51.1 g / cm / g / m ² , elongation (vertical width): 244%, bending resistance (cantilever) : 110mm, 30%
Modulus: It had a mechanical property value of 4.4 g / cm / g / m ² . With respect to this, the acoustic characteristics as the cone edge of the speaker were examined in the same manner as in Example 1.
As a result, the cone edge of the speaker had no problem in keeping the posture of the diaphragm correct, but the ability of the cone edge to follow the vibration was poor, and abnormal vibration might occur in the peripheral portion of the diaphragm during large deformation. It was

[0038]

The support of the speaker diaphragm in which the self-bonding nonwoven fabric of polyurethane fiber and the polyurethane film of the present invention are laminated and integrated is excellent in moldability, has a moderately small bending rigidity, and has a large internal loss. It has excellent acoustic characteristics. Its long-term practical durability is also excellent. By using the support of the speaker diaphragm of the present invention for a speaker, a speaker excellent in practical durability and acoustic characteristics can be obtained.

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Claims (1)

Claims: 1. A self-fusing nonwoven fabric made of polyurethane elastic fibers having an average fiber diameter of 7 to 30 µ and a polyurethane film are laminated and integrated, and the 30% modulus is 0.8 to 4 g /
A support for a speaker diaphragm, having a cm / g / m ² and a bending resistance of 100 mm or less.