JPH01232899A - Manufacture of speaker diaphragm - Google Patents

Abstract

PURPOSE:To easily manufacture a thin diaphragm or a diaphragm with a large diameter with productivity by rolling an inject molding component and forming a speaker diaphragm while the component is in the molten state to a degree capable of rolling. CONSTITUTION:A metallic die comprising injection parts 1, 2 and a cone part 3 is used and the component comprising 100-30wt.% of polymer and 0-70wt.% of fibrous packing agent is used to form the speaker diaphragm. In the case of forming, while the injected molding component stays in the molten state to a degree where the component is able to be rolled, the component is rolled to form the speaker diaphragm.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a method for manufacturing a speaker diaphragm, and more specifically to a method for manufacturing a speaker diaphragm from a polymer capable of forming an anisotropic melt (hereinafter referred to as a liquid crystal polymer). The present invention relates to a method of manufacturing a speaker diaphragm.

(Prior art) A speaker diaphragm is also called a diaphragm among the parts that constitute a speaker, and its specific elastic modulus E/ρ (E: curved elastic modulus, ρ :density) is as large as possible, and it is required to have an appropriate internal loss in order to smooth the frequency characteristics in the high frequency range.

Conventionally, in order to increase the specific modulus of elasticity, a method has been used in which carbon fibers are mixed into a diaphragm mainly made of Gi pulp. Furthermore, in recent years, the specific modulus of elasticity has been improved by mixing carbon fiber, mica, etc. into plastic materials.

On the other hand, in order to increase the internal loss, methods have been used in which the diaphragm is impregnated with various organic paints.

In addition, although liquid crystal polymers are easily oriented by applying shear stress and exhibit high strength and high elastic modulus, the film and sheet-like molded products that are normally obtained have strong anisotropy, making them unsuitable for speaker diaphragms. Ta. Ideally, it is thought that a diaphragm with good sound quality can be obtained by oriented two molecules radially from the center of the diaphragm, and as a method for manufacturing such a diaphragm,
JP-A-62-202699, JP-A-62-149
Japanese Patent No. 296 proposes a method for manufacturing a speaker diaphragm using a composition made of a liquid crystal polymer.

(Problems to be Solved by the Invention) However, in the method of mixing carbon fibers into Gi pulp, there is a limit to the amount of carbon fibers that can be mixed in, and it cannot be expected to increase the specific elastic modulus much. The method of mixing diaphragm or mica increases the melt viscosity, resulting in restrictions on molding, while the method of impregnating the diaphragm with an organic paint increases internal loss, but at the same time has problems such as a decrease in the specific modulus of elasticity. Also, JP-A-62-202699, JP-A-61-
Publication No. 149296 specifically discloses a production method using injection molding, but in such a method, even if liquid crystal polymer is known to have good flow, the fluidity is insufficient and thin vibrations occur. There was a problem in that it was difficult to mold a plate or a diaphragm with a large diameter.

An object of the present invention is to provide a method for manufacturing a speaker diaphragm having a large specific modulus of elasticity and a moderate internal loss.

Another object of the present invention is to provide a method for manufacturing a speaker diaphragm that can easily manufacture a thin diaphragm or a large diameter diaphragm with good industrial productivity.

(Means for Solving the Problems) As a result of extensive research in order to provide a method for manufacturing a speaker diaphragm that does not have the problems of the prior art as described above, the present inventors have discovered injection molding and rolling molding of liquid crystal polymer. It was discovered that the above objective could be achieved by combining
We have arrived at the present invention.

That is, the present invention provides a method for molding a speaker diaphragm using a composition consisting of 100 to 30% by weight of a polymer capable of forming an anisotropic melt and 0 to 70% by weight of a fibrous filler, which includes injection molding. The gist of the present invention is a method for producing a speaker diaphragm, which comprises rolling the composition to form the speaker diaphragm while the composition is in a molten state that can be rolled.

The liquid crystal polymer used in the present invention may be any polymer as long as it can form an anisotropic melt, but preferred specific examples include 2, for example,
Copolymer of p-hydroxybenzoic acid and polyethylene terephthalate disclosed in Publication No. 016, JP-A-54-7
Copolymer of p-hydroxybenzoic acid and 6-hydroxy-2-naphthoic acid disclosed in Japanese Patent Publication No. 7691
Polyester carbonate disclosed in JP-A No. 9-30727, copolymer of terephthalic acid, 2,6-naphthalene dicarboxylic acid, hydroquinone and p-hydroxybenzoic acid disclosed in JP-A-54-30290; 6-hydroxy- disclosed in Publication No. 56-10526
A copolymer of 2-naphthoic acid, hydroquinone and terephthalic acid, a copolymer of phenylhydroquinone and terephthalic acid disclosed in JP-A No. 53-65421, p- disclosed in JP-A-57-87423 Hydroxybenzoic acid, terephthalic acid, resorcinol, and 6-hydroxy-
Examples include copolymers of 2-naphthoic acid. Among these, liquid crystal polymers disclosed in Japanese Patent Publication No. 56-18016 and Japanese Patent Application Laid-open No. 77691/1989 are particularly preferred because of their excellent moldability.

In the present invention, 100 to 30 of these liquid crystal polymers are used.
% by weight and 0 to 70% by weight of fibrous filler.

As the fibrous filler used in the present invention, any filler that is used as a reinforcing agent for ordinary thermoplastic resins can be used, but specific examples include carbon fiber, potassium titanate whiskers, and glass fiber. Examples include inorganic fibers such as, and organic fibers such as aramid fibers. Among these, carbon fibers, potassium titanate whiskers, and aramid fibers are particularly preferred because they provide higher specific modulus, but carbon fibers and aramid fibers are most preferred because they have a low specific gravity and high specific modulus. . These fibrous fillers are preferably surface-treated with a sizing agent such as a silane-based, epoxy-based, or urethane-based sizing agent in order to increase their affinity with the liquid crystal polymer.

If the content of the fibrous filler in the composition exceeds 70% by weight, the fluidity of the composition will be extremely reduced, making it difficult to mold the diaphragm. On the other hand, the object of the present invention can be achieved even if the fibrous filler is not present in the composition. However, when strong vibration is applied to the fibrous filler, it tends to crack in the diametrical direction. ~50% heavy view, especially preferably 15-30
It is desirable to include % by weight of fibrous filler.

In the present invention, additives such as pigments, heat stabilizers, and plasticizers may be contained in the composition as long as they do not interfere with the objects of the present invention.

The composition consisting of a liquid crystal polymer and a fibrous filler used in the present invention may be prepared by any method as long as each component is uniformly mixed. Those prepared by melt-kneading are preferred.

In the present invention, a speaker diaphragm is manufactured by injection molding such a composition and rolling the composition while it is in a molten state to the extent that it can be rolled. For this purpose, one composition may be rolled while being injection molded or immediately after injection molding. These operations can be preferably carried out using a press mold dedicated machine that has been developed in recent years. It can also be done using a general injection molding machine, but in that case it is done manually.

It is preferable to make appropriate modifications.

The mold temperature (T,) is preferably a high temperature in order to obtain good fluidity, but a moderately low temperature in order to obtain a good molding cycle, and specifically, it should be in the following range. preferable.

T9≦T, ≦T, , -(TII-T,)1/4 [
However, T and n are the melting temperatures of the composition (measured by DSC)
(° C.), and T9 represents the second-order transition temperature of the composition (measured by viscoelasticity) (“C).] In addition, it is particularly preferable that the temperature is within the following range.

T, -(T, -TI)3/4≦T,≦Tchi-T
It is preferable that the temperature (T2) of the 1/3 composition is higher when the temperature of the press mold is low.
Since the diaphragm targeted by the present invention is thin, it is generally preferable to set the temperature sufficiently higher than its melting temperature (T).
Specifically, it is preferable that the temperature is higher than T by 10°C or more, more preferably 20°C or more, or 30°C or more.

During rolling, the two compositions are elongated and rapidly cooled and solidified, so it is preferably rolled within a short time, specifically within 3 seconds, and particularly preferably within 1 second.

For rolling, especially for rolling to obtain a solid diaphragm, it is preferable that the press pressure is high, specifically 5 kg/ant.
Above, it is particularly preferable that it is 15 kg/c+J or more.

FIG. 1 is a perspective view showing an example of a mold used in the present invention. For example, in the present invention.

A mold having injection parts 1 and 2 as shown in Figure 1 is used, but when injecting one composition, the mold is kept at the minimum necessary opening, specifically 10+n or less, and the injection A preferred method is to perform rapid rolling during or immediately after rolling. If the opening of the mold is 10 fl or less, molding defects due to sag will not be observed in both vertical and horizontal molds. The amount of injection of the composition in step - is required to be enough to spread over the cone portion after rolling, and is preferably slightly larger.

(Example) The present invention will be described below with reference to two examples.

In addition, for molding in one example, the mold attachment part of the 6 oz molding machine was modified and a horizontal 100 ton press was installed.
We used a model that had been modified so that it could be rolled while being injected. Also, as a mold.

Basically, the one shown in Fig. 1 was used, but the injection part 1 (
The diameter of the spool is 41. The thickness of the injection part 2 (cone part) was set to IB.

Reference Examples 1 to 3 Consists of hydroxybenzoic acid residues, ethylene glycol residues, and terephthalic acid residues.

The molar ratio of ethylene glycol residues and terephthalic acid residues is substantially equal, and the molar ratio of hydroxybenzoic acid residues and terephthalic acid residues is 80/20, and 3
Carbon fiber (HTA-C6-N, manufactured by Toho Rayon) was added to liquid crystal polyester whose melt viscosity was 1100 poise at a temperature of 300°C and a shear rate of 1000 sec' as measured by a flow tester (Shimadzu CFT-500). A twin-screw extruder (PCM-45 manufactured by Ikegai Iron Works) was used so that the proportion in the chips after kneading was 30% by weight (Reference Example 1), 20% by weight (Reference Example 2), or 10% by weight (Reference Example 3). The mixture was kneaded at 300°C to form chips. In addition, the specific gravity of the chip of Reference Example 1 is 1.49. The one of reference example 2 is 1.46. The value of Reference Example 3 was 1.43.

Reference example 4 Residues of rose hydroxybenzoic acid and 2-hydroxy-6-
80 parts by weight of liquid crystal polyester (manufactured by Polyplastics, Vectra A-950) consisting of naphthoic acid residues,
20 parts by weight of the carbon fibers used in Reference Example 1 were kneaded at 315°C using the twin-screw extruder used in Reference Example 1 to form chips.

Note that the specific gravity of the chip was 1.46.

Reference Example 5 80 parts by weight of the liquid crystal polyester used in Reference Example 1 was added with potassium titanate whiskers (manufactured by Daijin Chemical Co., Ltd.).

20 parts by weight of Tismo fibers were kneaded using the twin-screw extruder used in Reference Example 1 to form chips. Note that the specific gravity of the chip was 1.57.

Example 1 After the chips of Reference Example 1 were completely dried, the temperature of the second composition was 340°.
+r/c to 20 while injecting at C1 mold temperature 160℃
Rolling was performed at a pressure of ni to obtain a diaphragm having a cone portion with an outer diameter of 80 fins, an inner diameter of 35+n, a thickness of 0.35 fins, and a height of 20 M1.

The cone portion of the obtained diaphragm was cut out, and the elastic modulus in the diametrical direction measured by the sound velocity was 4.5×10”dyne/c1.
11, which is extremely high, and the specific elastic modulus is 3.0×10”c
It had an extremely high m2/5ec2, and had an internal loss of 0.055, showing excellent performance as a speaker diaphragm.

Moreover, this molding could be performed in a cycle of 60 seconds or less, and the productivity was also extremely good.

Examples 2 to 4 After the chip of Reference Example 2 was completely dried, the temperature of the 1Mi product was 330.
While injecting at a mold temperature of 180°C (Example 2), 160°C (Example 3) or 140°C (Example 4),
12 kg/al (Example 2), 15 kg/c+
J (Example 3) or 20 kg/cn (Example 4)
) to obtain a diaphragm of the same size as in Example 1.

The cone portion of the obtained diaphragm was cut out, and the elastic modulus in the diametrical direction measured by the sound velocity was 4.3 X I QII6yn
e/cJ (Example 2), 4.2X10th dyne/c
nl (Example 3), 4. OX 10”dyne/
cnt (Example 4), which is extremely high, and the specific elastic modulus is also 2.
゜9 x 10”cm27sec2 (Example 2)
, 3. I X 10 "cm"/sec" (Example 3), 3. I X 10 "cm2/5e
c2 (Example 4), which is extremely high, and the internal loss is also 0.055 (Example 2) and 0.055 (Example 3).
, 0.055 (Example 4), and had excellent performance as a speaker diaphragm.

Example 5 After the chip of Reference Example 3 was completely dried, the temperature of the 1Mi product was 330.
'C, 25 kg while injecting at a mold temperature of 160℃
/ cnt of pressure, the outer diameter of the cone part is 120
mm, inner diameter 55mm, thickness 0.25mm, height 30mm
diaphragm was obtained.

The cone portion of the resulting diaphragm was cut out, and the elastic modulus in the diametrical direction measured by the sound velocity was 3.8 x 10”dyne/
Cot, which is extremely high, and has a specific elastic modulus of 2.7X10”
cm''/5ec2, which was extremely high, and the internal loss was 0.06, indicating excellent performance as a speaker diaphragm.

Further, although the molding was thin and large in size, it was possible to easily perform the molding within a cycle of 60 seconds, and the productivity was also extremely good.

Example 6 After the chip of Reference Example 4 was completely dried, the two-composition Komabe degree was 350°.
While injecting at C1 mold temperature 180℃, 2Q kg/
Rolling was performed at cnl pressure to obtain a diaphragm of the same size as in Example 1.

The cone portion of the obtained diaphragm was cut out, and the elastic modulus in the diametrical direction measured by the sound velocity was 4.3×10”dyne/cI.
Extremely high at 11, and the specific elastic modulus is 2.9X1ONcm
It had an extremely high value of 2/5ec2, and had an internal loss of 0.06, exhibiting excellent performance as a speaker diaphragm.

Example 7 After completely drying the chip of Reference Example 5, the temperature of 2 composition Komabe was 330°C.
, 15kg/cn (while injecting at a mold temperature of 170℃)
Rolling was performed under pressure to obtain a diaphragm of the same size as in Example 1.

The cone portion of the obtained diaphragm was cut out, and the elastic modulus in the diametrical direction measured by the sound velocity was 3.8
e/c+J, which is extremely high, and the specific elastic modulus is also slightly lower than those using carbon fiber due to its high specific gravity2.6
X 10 IIcm"/5ec2, which was higher than that of commercially available products, and the internal loss was 0.05, indicating excellent performance as a speaker diaphragm.

Example 8 A diaphragm of the same size as Example 1 was obtained in the same manner as in Example 1 except that the liquid crystal polyester used as the raw material in Reference Example 1 was used and the press pressure was lowered to 19 kg/cnl.

The cone portion of the obtained diaphragm was cut out, and the elastic modulus in the diametrical direction measured by the sound velocity was 3.3
Extremely high e/crA and specific elastic modulus of 2.4X10
1ICm2/5eC2, and internal loss is 0.06
It had excellent performance as a speaker diaphragm.

Comparative Example 1 In order to obtain the same diaphragm as in Example 1 by injection molding, the outer diameter of the cone part was 80u+, the inner diameter was 35mm, and the thickness was 0.
A mold with a diameter of 35+a+, an injection part (inside cone) thickness of 1° Owm, and an injection part (spool) diameter of 4 mm was used.

Composition temperature 330°C, mold temperature 150°C, injection pressure 12
Injection molding was performed at 50 kg/ctA. but.

Only 70% of the cone portion could be filled, and a diaphragm of the desired size could not be obtained.

(Effect of the invention) According to the present invention, a high performance speaker diaphragm is provided.

It can be easily manufactured in both thin and large sizes.

The speaker diaphragm obtained according to the present invention has a high specific modulus of elasticity and an appropriate internal loss.

It is expected that it will be suitably used in speakers for medium and low frequencies.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view showing an example of a mold used in the present invention.

Claims (1)

[Claims] (1) Polymer 100-30 capable of forming an anisotropic melt
In a method for molding a speaker diaphragm using a composition comprising 0 to 70% by weight of a fibrous filler and a fibrous filler, the composition is molded while the injection-molded composition is in a molten state that can be rolled. A method of manufacturing a speaker diaphragm, comprising rolling the speaker diaphragm to form the speaker diaphragm.