JPH0993681A - Speaker cabinet and manufacturing method thereof - Google Patents

Abstract

(57) Abstract: A speaker cabinet having good moldability, high productivity, light weight, excellent mechanical properties such as tensile strength, high rigidity, and excellent material recyclability, and a manufacturing method thereof. To provide. SOLUTION: This is made of a composite material in which a fibrillated LCP (thermotropic liquid crystal polyester resin) 2 is dispersed in a matrix 1 made of a thermoplastic resin. In the manufacturing, in each of the steps of forming the composite pellets 16 by the extruder 10 and molding the speaker cabinet 3 by the injection molding machine 14, the extrusion temperature and the injection molding temperature are respectively higher than the melting temperature of the thermoplastic resin. And a temperature in the range below the liquid crystal transition temperature of the LCP, and the shear rate at the die of the extruder is 3
It is controlled to 00 SEC-1 or higher.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a speaker cabinet in the field of audio equipment and a method of manufacturing the speaker cabinet, and in particular, a speaker cabinet using a novel material, which is optimal for structural parts of the speaker. And its manufacturing method.

[0002]

2. Description of the Related Art A conventional speaker cabinet 3 is
As shown in the overall cross-sectional structure in FIG. 7, a box-like shape is provided, a sound output port 3b is formed in the front baffle 3a, and a speaker 4 is attached so as to close the sound output port 3b. It is one member that constitutes. The cabinet 3 covers the back surface of the speaker 4 and seals the back space, or configures an acoustic circuit as needed. In either case, the heavy speaker 4 is firmly held at a predetermined position, and the speaker 4 is operated during operation. Vibrates violently, self-vibration,
The quality of the reproduced sound, such as unwanted radiation, should not be degraded. In addition, when used as a speaker device, the bottom plate of the cabinet may be placed on the floor or may be suspended from the top plate. Sufficient strength, rigidity, creep resistance, as a material for such cabinets for speakers,
Although it is required to have no internal loss, no air permeability, etc., in particular for a cabinet of a vehicle-mounted speaker, it is necessary to have particularly excellent lightweight and heat-resistant creep properties in addition to the above properties. Wood (plywood) is often used as the material for conventional speaker cabinets for large-capacity cabinets, but it is lightweight for vehicle-mounted speakers, and can be mass-produced or integrated with other accessory parts. An injection molding cabinet made of a thermoplastic resin is used for the purpose of cost reduction.

[0003]

The injection molding cabinet made of the above-mentioned thermoplastic resin can realize a reduction in weight or a reduction in cost, but the use of only the thermoplastic resin causes mechanical strength such as rigidity and heat-resistant creep resistance. Due to insufficient properties, it was usually necessary to add inorganic fillers such as glass fibers, carbon fibers, talc, mica, whiskers. However, increasing the amount of additive impedes the fluidity of the molten resin, limiting the mass productivity and flexibility of the shape, which were the advantages of the resin cabinet, and the density also increased, which defeats the purpose of weight reduction. However, there is a drawback in that the internal loss, which greatly contributes to suppressing the self-vibration of the cabinet, is also reduced.
Furthermore, in recent years, recyclability has been required for environmental protection, but with thermoplastic resins containing additives for the purpose of improving mechanical properties, the additives break during the crushing process and the initial reinforcing effect is significantly reduced. Then, there was a problem to be solved that recycling is impossible.

Therefore, the present invention is intended to solve the problem that the conventional cabinet for a speaker has, and in order to solve the problem, a thermoplastic resin is added with a fibrillated thermotropic liquid crystal polyester resin. An object of the present invention is to solve the above-mentioned drawbacks and problems of the conventional thermoplastic resin cabinet by molding under the conditions, and to provide a speaker cabinet that is lightweight and has improved rigidity, heat-resistant creep resistance, mass productivity, and recyclability. .

[0005]

A speaker cabinet and a method for manufacturing the same according to the present invention for achieving the object will be described with reference to the reference numerals used in the embodiments.
The first aspect of the present invention is to provide a matrix 1 made of a thermoplastic resin,
A speaker cabinet characterized by comprising a mixed material in which fibrillated thermotropic liquid crystal polyester resin (hereinafter abbreviated as LCP) 2 is dispersed.

A second invention is the speaker cabinet according to the first invention, wherein the mixing ratio of the LCP2 is 5% to 80%.

A third invention is the same as the first invention, wherein the thermoplastic resin matrix 1 is polypropylene (hereinafter referred to as P
Abbreviated as P) or polybutylene terephthalate (hereinafter P
BT) or polyamide 6 (hereinafter abbreviated as PA6)
Alternatively, acrylonitrile butadiene styrene (abbreviated as ABS hereinafter) or polystyrene / polyamide 6 / poniphenylene ether (abbreviated as PS / PA6 / PPE hereinafter), or acrylonitrile butadiene styrene / polybutylene terephthalate (abbreviated ABS / PBT hereinafter) Abbreviated) or polystyrene / poniphenylene ether (hereinafter abbreviated as PS / PPE) or acrylonitrile.
Butadiene / styrene / polycarbonate (hereinafter ABS
/ PC) or a polycarbonate / polybutylene terephthalate (hereinafter abbreviated as PC / PBT) thermoplastic resin selected from the speaker cabinets. It is a cabinet for makers.

In a fourth aspect of the present invention, the thermoplastic resin forming the matrix 1 and the LCP 2 are dry-blended and the extruder 1 is used.
In the manufacturing method of the speaker cabinet in which the composite pellet 16 is formed by 0 and the composite pellet 16 is injection-molded into the speaker cabinet 3 having a predetermined shape, the composite pellet 16 is formed by the extruder 10. The extrusion temperature is a melting temperature T1 of the thermoplastic resin or more and a temperature T in the range of the liquid crystal transition temperature T2 of the LCP or less, and the shear rate at the die of the extruder is 300 SEC ^-1 or more, and a speaker cabinet. The method for manufacturing a speaker cabinet is characterized in that the injection molding temperature in the molding step is a temperature T in a range not lower than the melting temperature T1 of the thermoplastic resin and not higher than the liquid crystal transition temperature T2 of the LCP.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the speaker cabinet and the method for manufacturing the speaker cabinet will be described with reference to FIGS. 1 to 3 from the first to third inventions. FIG. It is a partially expanded half sectional view of the speaker cabinet 3 which belongs to the invention. The shape of the cabinet 3 is a well-known bass reflex type, and is manufactured by dividing into a baffle 3a having a sound emission port 3b for mounting the speaker 4 and a port 3c, and a cavity 3d covering the back surface of the speaker 4. Has been done. Enlarge a part of the cross section,
The composition of the composite material forming the cabinet is as follows: matrix 1 made of thermoplastic resin has fibrillated LCP (thermotropic liquid crystal polyester resin) 2 dispersed therein, and this fibrillated L
CP serves as a reinforcing material to increase tensile strength, and is a composite material for a cabinet having rigidity required for a speaker cabinet.

FIG. 2 shows a speaker cabinet 3 from a mixture of a thermoplastic resin, which is a raw material of the above mixed material, and LCP.
Fig. 3 shows the state of the composition during the manufacturing process and the mixture accompanying each process, and Fig. 3 shows the temperature condition of each process. In FIG. 2, the thermoplastic resin raw material 16a and the LCP raw material 16
The mixture obtained by dry blending b and b is loaded into an extruder 10, melted by heating and extruded from a die to form a strand that becomes a composite pellet. As shown in FIG. 3, the heating temperature is equal to or higher than the melting temperature T1 of the thermoplastic resin and L
It is set to a temperature T in a range not higher than the liquid crystal transition temperature T2 of CP. This set temperature T is the melting temperature T of the thermoplastic resin.
It goes without saying that if it is lower than 1, extrusion is impossible. Further, when the set temperature T becomes higher than the liquid crystal transition temperature T2 of the LCP, the strength peculiar to the LCP disappears.

In the preparation process, the thermoplastic resin raw material 16a and the LCP raw material 16b are uniformly mixed at a temperature at which they are melted together, and spherical LCPs are dispersed in the thermoplastic resin raw material 16a. (Enlarged sectional view A). The mixture is cooled as it is extruded from the die, but the size of the fibrils of the LCP in the composite pellet after cooling depends on the apparent shear rate of the LCP extrudate,
As a result of experiments, it is necessary that the shear rate is 300 SEC ^-1 or more in order to obtain a size of 20 μm or more that functions as a filler. When extruded at such a shear rate, the LCP in the mixture disperses into an elongated oval-like shape and disperses (enlarged cross-sectional view B), and when it goes out from the die, it fibrillates and becomes aligned in the extrusion direction. And dispersed (enlarged sectional view C). The extruded strad is cooled by the cooling unit 11, centrifuged by the roller 12 to a predetermined thickness, cut by the pelletizer 13, and the fibrillated LCP 2 is dispersed and mixed in a certain direction in the thermoplastic resin matrix 1. The composite pellets 16 are formed.

The composite pellet 16 is loaded into the injection molding machine 14 and injected into the mold 15 to form the baffle 3a or the cavity 3d of the speaker cabinet 3 (enlarged sectional view D). The melting temperature of the composite pellets 16 in the injection molding machine 14 is set to a temperature T in the range of not less than the melting temperature T1 of the thermoplastic resin and not more than the liquid crystal transition temperature T2 of the LCP, like the melting temperature in the extruder. .

In the molding process, the LC in the composite pellet 16 is
In order to maintain the shape of the P fibrils after the molding, the molding temperature is equal to or lower than the liquid crystal transition temperature T2 of the LCP as described above, and the melting temperature T1 of the thermoplastic resin forming the matrix 1
It must be above. Therefore, it is necessary to combine an LCP having such a temperature range with a thermoplastic resin. Generally, a melting temperature T1 of a general-purpose thermoplastic resin is about 1
Since the temperature is 80 to 270 ° C., the liquid crystal transition temperature T2 is 280.
It is sufficient to select an LCP having a temperature of ℃ or higher.

The above-mentioned composite pellet of the present invention is characterized in that the internal LCP, which is a filler, is an organic substance, and therefore has a very large mechanical internal loss as compared with the conventional synthetic resin using an inorganic filler. .

Further, in the conventional synthetic resin using an inorganic filler, the filler is destroyed in the pulverizing process during recycling, and the strength equivalent to that of the first molded product using a new material cannot be obtained. According to the constitution of the present invention, since the filler is a thermoplastic LCP, even if it is crushed at the time of recycling, it will be fibrillated again at the time of making pellets, so that the strength will not be deteriorated even if it is reused.

[0016]

Embodiments of the speaker cabinet of the present invention will be specifically described below. FIG. 1 is a partially enlarged half sectional view of a speaker cabinet 3 according to an embodiment of the first aspect of the invention. The characteristic of the cabinet of this embodiment lies in the constituent materials. The composition of the composite material composing the cabinet is shown by enlarging a part of the cross section, and the matrix 1 made of a thermoplastic resin has fibrillated LCP (thermotropic). Liquid crystal polyester resin 2 is dispersed, and the fibrillated LCP serves as a reinforcing material to increase the tensile strength and to have a rigidity required for a speaker cabinet, and a composite material for a cabinet. Become.

The manufacturing method of the above embodiment will be described in detail. As the thermoplastic resin of the matrix 1, PP, PBT, PA is used.
6, ABS, PS / PA6 / PPE, PS / PPE, A
9 kinds of resins such as BS / PBT, ABS / PC, PC / PBT are used as samples, and LC is applied to each sample resin.
As P2, a thermotropic liquid crystal polyester resin having a liquid crystal transition temperature T2 of 280 ° C. is dry-blended in an arbitrary range of 5 to 90% by weight ratio, melt-kneaded at a heating cylinder temperature of 290 ° C. using a kneader, and a capillary radius of 1 mm Extruded with a die and then cooled with water, and the resulting strand is 3 mm long
A composite pellet was prepared by cutting into pieces. The apparent shear rate during extrusion is 2500 SEC ^-1 .

Next, the speaker cabinet 3 of the present invention shown in FIG. 1 was prepared by injection molding using these composite pellets. The temperature at the time of injection molding of this cabinet was set as follows for each thermoplastic resin sample, as the temperature at which the matrix 1 resin melts and the fibrils of LCP do not melt. In addition, the range of the optimum mixing ratio of the matrix resin and LCP based on the experimental results is also described.

[0019]

[Table 1]

As a typical example, a part of a trial-produced cabinet was cut out for an example in which PP and LCP were mixed, and tensile strength, spiral flow and density were compared with a conventional example in which glass fiber was added. 4 and FIG. 5, respectively. In the conventional example, since the glass fiber is longer than the fibril of LCP, the reinforcing effect for a small amount of addition is great, but the spiral flow decreases, so
The addition amount of 50% is the limit, and since the compatibility with the matrix 1 is poor, the reinforcing effect reaches a ceiling. Spiral flow also decreases with the increase of the addition amount of LCP, but it does not decrease as much as the addition of glass fiber, and the addition amount of strength is 40 to 5
When it exceeds 0%, it becomes stronger than that of glass fiber. There is also a range of LCP content that balances strength and spiral flow. The numerical values in the range of the mixing ratio in the above table are based on such experimental results.

FIG. 6 shows the results of measuring the tensile strength of a cabinet prepared by recycling LCP 30% and PP 70% at a ratio of 1 to 10 times. The results show that no deterioration of strength was observed after about 10 times, indicating that the material of the present invention has excellent recyclability.

The embodiments which are considered to be representative of the present invention have been described above. However, the present invention is not necessarily limited to only the structures of the embodiments, and has the above-mentioned constitutional requirements according to the present invention. The present invention achieves the object of the present invention and can be appropriately modified and implemented within the range having the following effects.

[0023]

As is apparent from the above description, in the speaker cabinet and the manufacturing method thereof according to the present invention, an appropriate amount of LCP is mixed with the thermoplastic resin matrix, and the LCP micro phase is mixed in the continuous phase of the matrix resin. Since the fibrillated dispersed phase exhibits a reinforcing action in place of the conventional inorganic filler, it has good moldability, is lightweight, and has excellent mechanical properties such as tensile strength and recyclability. Among the examples of the present invention, the results obtained by comparing the LCP and PP (polypropylene) mixed with the conventional example to which glass fiber was added are shown below.

FIG. 4 shows the values of the spiral flow, which shows the rigidity of the cabinet with respect to the mixing ratio of LCP, and which relates to the tensile strength and the quality of the moldability. Compared to the case of adding glass fiber which is a conventional example, the spiral flow is less decreased and the moldability is good, and the production efficiency can be increased. Regarding the tensile strength, the amount of glass fiber added is limited from the standpoint of spiral flow, whereas the composite material of the present invention can be added in large amounts, so the strength can be increased.

FIG. 5 shows the value of density with respect to the mixing ratio of LCP. Regarding the density, since LCP has a lower density than glass fiber, the composite material of the product itself has a low density. Therefore, if the weight is the same, it is possible to increase the strength, and conversely, with the same strength. If you can reduce the weight,
Excellent suitability as a material for speaker cabinets.

FIG. 6 shows data expressing the recyclability of the cabinet prepared with the ratio of LCP 30% and PP 70%. As a result of measuring the tensile strength of the cabinet that was recycled and recreated 1 to 10 times, 10
Deterioration of strength was not observed in about a cycle, demonstrating that the material of the present invention has excellent recyclability and meets recent requirements for environmental protection.

From the above results, the speaker cabinet of the present invention has good moldability and high productivity, is lightweight, has excellent mechanical properties such as tensile strength and internal loss, and has high strength and excellent recyclability. Therefore, it is possible to expect the effect of being able to contribute to environmental conservation.

[Brief description of drawings]

FIG. 1 is a partially enlarged sectional view of a speaker cabinet according to an embodiment of the present invention.

FIG. 2 is a process explanatory view showing the manufacturing method of the embodiment.

FIG. 3 is a temperature control chart in the manufacturing method of the embodiment.

FIG. 4 is a graph showing the results of experiments on the tensile strength and spiral flow of the examples.

FIG. 5 is a graph showing experimental results regarding the density of the example.

FIG. 6 is a graph showing the experimental results regarding the recyclability of the examples.

FIG. 7 is a cross-sectional view illustrating the structure of a general speaker.

[Explanation of symbols]

 1 Matrix 2 LCP 3 Cabinet 4 Vibration System 5 Magnetic Circuit 6 Cabinet 10 Extruder 11 Cooling Part 12 Roller 13 Pelletizer 14 Injection Molding Machine 15 Mold 16 Composite Pellet

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code Agency reference number FI Technical indication location // B29K 67:00

Claims (4)

[Claims] 1. A speaker comprising a composite material in which a fibrillated thermotropic liquid crystal polyester resin (hereinafter abbreviated as LCP) (2) is dispersed in a matrix (1) made of a thermoplastic resin. cabinet. 2. The mixing ratio of the LCP (2) is 5% to 80.
The speaker cabinet according to claim 1, wherein the speaker cabinet is%. 3. The thermoplastic resin matrix (1) is polypropylene (hereinafter abbreviated as PP), polybutylene terephthalate (hereinafter abbreviated as PBT), or polyamide 6
(Hereinafter abbreviated as PA6) or acrylonitrile butadiene styrene (hereinafter abbreviated as ABS) or polystyrene / polyamide 6 / poniphenylene ether (hereinafter PS)
/ PA6 / PPE) or acrylonitrile.
Butadiene / styrene / polybutylene terephthalate (hereinafter abbreviated as ABS / PBT) or polystyrene / poniphenylene ether (hereinafter abbreviated as PS / PPE) or acrylonitrile butadiene styrene / polycarbonate (hereinafter abbreviated as ABS / PC) or polycarbonate / Polybutylene terephthalate (hereinafter PC / P
The speaker cabinet according to claim 1, wherein the speaker cabinet is made of a thermoplastic resin selected from among BT). 4. A thermoplastic resin constituting the matrix (1) and an LCP (2) are dry-blended to prepare a composite pellet (16) by an extruder (10), and the composite pellet (16).
In the method of manufacturing a speaker cabinet in which a speaker cabinet having a predetermined shape is formed by injection molding, the extrusion temperature in the step of producing the composite pellets (16) by the extruder (10) is the melting temperature T1 of the thermoplastic resin. The temperature T is above the liquid crystal transition temperature T2 of the LCP, and the shear rate at the die of the extruder is 3 or more.
00SEC ^-1 or more, and the injection molding temperature in the step of molding into the speaker cabinet is the melting temperature T of the thermoplastic resin.
A method for manufacturing a speaker cabinet, wherein the temperature T is in the range of 1 or more and the liquid crystal transition temperature T2 of the LCP or less.