JP2764516B2 - Japanese musical instrument parts made of plastic - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plastic musical instrument part.

[0002]

2. Description of the Related Art Hitherto, ivory has been the main material of this kind of Japanese musical instrument parts in terms of feel when touched by hand, tone when used, appearance, and abrasion resistance. In addition, acrylonitrile-butadiene-styrene resin (AB
S resin) and urea resin.

[0003]

However, the import and export of ivory has been banned under the Washington Convention, and it has become impossible to use it as a material for Japanese musical instrument parts.

On the other hand, acrylonitrile / butadiene / styrene resin and urea resin are excellent in moldability, but have no hygroscopicity, and are inferior in acousticity and feel to ivory, and have chargeability. There is a problem that dust easily adheres to the surface.

The present invention has been made to solve the above problems, and to provide a plastic musical instrument part which is hygroscopic, has the same tactile and acoustic properties as ivory, is inexpensive, and has excellent moldability. With the goal.

[0006]

Means for Solving the Problems The present inventors have conducted intensive studies to achieve the above object, and as a result, have noticed that the cellulose derivative resin is rich in hygroscopicity, has a good feel, is strong, and has excellent moldability. However, it has been found that by adding specific silica as an inorganic filler to the cellulose derivative resin, the surface hardness is improved and the acoustic properties and the tactile properties are equivalent to those of ivory.

The present invention has been made based on this finding. Japanese plastic musical instrument parts having a silanol group of 3.0 or less per 100 square angstroms and a BET specific surface area of 100 to 210 m ² / g have been proposed. It is made of a cellulose derivative resin containing silica and has a surface hardness of 82 or more in durometer hardness. In addition, the plastic Japanese musical instrument part is any one of a shamisen repellent, a thread-wound, a piece, a kotoboshi, and a Taisho koto finger button.

[0008]

This time, the present inventor has found that the cellulose derivative resin has a silanol group number of 3.000 per 100 square angstroms.
It has been found that when silica having a BET specific surface area of 100 to 210 m ² / g is contained at a value of 0 or less, the surface hardness is improved and the acoustic properties and the tactile properties are equivalent to those of ivory.

[0009]

The cellulose derivative resin used in the present invention includes cellulose acetate resin, cellulose acetate propineato resin, and cellulose acetate butyrate resin, and cellulose acetate resin is preferred from the viewpoint of cost.

As the silica to be added to the cellulose derivative resin, silica prepared by either a wet method or a dry method can be used.
Less than 3.0 per 0 square Angstroms and B
It is necessary that the silica satisfy the condition of 100 to 210 m ² / g in ET specific surface area.

[0011] The number of silanol groups can be calculated from the following formula based on the specific surface area obtained by the adsorption of water vapor.

[0012]

(Equation 1)

It is assumed that one water molecule is adsorbed on one silanol group.

The reason why the number of silanol groups is set to 3.0 or less per 100 square angstrom is that if the number of silanol groups exceeds 3.0, a large amount of water is adsorbed on the silica surface, so that a mixture of cellulose derivative resin and silica is heated. This is because foaming occurs during the melting and kneading steps and hydrolysis of the cellulose derivative resin is promoted.

The BET specific surface area can be determined from the amount of nitrogen gas adsorbed by the BET method.
The BET specific surface area is specified in TMD 3037, and is used as a substitute for the basic particle diameter of silica.
In the present invention, the BET specific surface area is 100 to 210 m ^2.
The reason is that if the BET specific surface area is less than 100 m ² / g, the silica particle size becomes coarse, and a product obtained by blending and molding the silica cannot have a smooth surface and sufficient hardness. And a BET specific surface area of 210 m ² / g
If the ratio exceeds the above, the cohesive force of the silica particles increases and the dispersion of the silica in the cellulose derivative resin becomes extremely poor.

In the present invention, the reason that the above specific silica is selected as the inorganic filler to be added to the cellulose derivative resin is that it requires a smaller amount of addition than other silica or other inorganic fillers such as calcium carbonate. Surface hardness is obtained, and the decrease in fluidity is small,
Thereby, the injection moldability is excellent. In addition, since the silanol group on the silica surface has a hygroscopic property, even if it is added to the cellulose derivative resin, the synergistic effect is exhibited without impairing the hygroscopic property of the cellulose derivative resin.

In the present invention, the durometer hardness is A
This is a D type (D type) whose measurement method is defined in STM D 676. And a durometer hardness of 82
In order to obtain a product having the above surface hardness, about 15 to 40 parts by weight of the silica is contained in 100 parts by weight of the cellulose derivative resin. If the content is less than 15 parts by weight, the obtained product has a surface hardness of 82 or less and is easily scratched by nails or the like, and if the content exceeds 40 parts by weight, the moldability is poor. Because it is inferior.

Further, when silica is blended with the cellulose derivative resin and injection molding is performed, a phthalate plasticizer such as dimethyl phthalate, diethyl phthalate, dibutyl phthalate or the like is used in order to obtain good injection moldability. For example, in the case of a cellulose acetate resin, the amount of the plasticizer may be about 20 to 50 parts by weight based on 100 parts by weight of the resin. If the added amount of the plasticizer is less than 20 parts by weight, the flowability is remarkably reduced and the injection molding is liable to be difficult.
Or discolor. Further, when the amount of the plasticizer exceeds 50 parts by weight, the fluidity is improved, but the obtained resin product becomes flexible and the amount of silica must be increased in order to increase the hardness. , Impact strength decreases.

In order to prevent thermal degradation of a cellulose derivative resin containing silica, for example, a weak organic acid,
Epoxy compounds, phosphites, thioether phosphites, phenol derivatives, thiophosphites, imidazole, amine derivatives, heat stabilizers such as metal soaps may be added. It may be appropriately set according to the type and the amount thereof, and an anthraquinone-based dye or pigment such as titanium oxide may be added for coloring a material containing silica in a cellulose derivative resin. The amount of addition may be appropriately set according to the type of Japanese musical instrument part to be colored.

Next, specific examples of the present invention will be described together with reference examples.

Example 1 100 parts by weight of cellulose acetate, 30 parts by weight of silica having a silanol group number of 2.1 per 100 square angstroms, a BET specific surface area of 136 m ² / g and an average particle size of 0.9 μm, and a plasticizer 27 parts by weight of a phthalate ester plasticizer, 0.2 parts by weight of an epoxy compound and 0.3 parts by weight of an alkyl phosphite as a heat stabilizer, and 2.5 parts by weight of a white pigment as a colorant, The mixture was stirred and mixed at 80 ° C. for 4 hours using a universal mixing stirrer, and simultaneously dried to a water content of 0.2% by weight or less. The dried mixture was melt-kneaded at 220 ° C. with an extruder having a diameter of 40 mm, extruded and pelletized.

The pellets were used to form a shamisen repellent 1 shown in FIG. 1 using an injection molding machine. The specific gravity, water absorption, surface hardness, and coefficient of friction of the repellent 1 thus prepared were measured, and the results are shown in Table 1.

The measuring method is as follows. (1) Specific gravity is based on ASTM D792. (2) Water absorption is based on ASTM D570. (3) Surface hardness (durometer hardness) is ASTM D6
76. (4) The coefficient of static friction conforms to JIS K 7125, and the measurement conditions are a crosshead speed of 50 mm / min and a weight of 20.
0 g, and deerskin was used as a mating material.

Reference Example The specific gravity, water absorption, surface hardness, and coefficient of static friction of ivory made of ivory were measured in the same manner as in Example 1, and the results are shown in Table 1.

[0025]

[Table 1]

As is clear from Table 1, Example 1 of the present invention has the same surface hardness and coefficient of static friction as the ivory repellent of the reference example, and is inferior in water absorption, but has a good feel to the finger. It was hard to slip even when sweating, it was easy to play, and it was comparable to ivory repellent.

Example 2 A koto post 2 shown in FIG. 2 was prepared from the material of Example 1 by an injection molding machine.

When a performance was performed using the prepared koto pillar as a koto, a tone comparable to that of an ivory koto pillar was obtained.

In the above embodiment, the case of repellent and koto poles has been described. However, the plastic material of the present invention is not limited to this. Good.

[0030]

According to the present invention, the surface hardness is the same as that of ivory, the feel to the fingers is excellent, the moisture absorption is low, the chargeability is low, and the dust hardly adheres to the surface. This has the effect of providing a low-cost plastic Japanese musical instrument part having the characteristic and acoustic properties.

[Brief description of the drawings]

FIG. 1 is a perspective view of one embodiment of the present invention;

FIG. 2 is a perspective view of another embodiment of the present invention.

[Explanation of symbols]

 1 repellent, 2 kotoshira.

 ──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-49-34528 (JP, A) JP-A-50-98830 (JP, A) JP-A-51-6009 (JP, A) 9112 (JP, A) JP-A-59-195689 (JP, A) JP-A-1-274196 (JP, A)

Claims (2)

(57) [Claims] 1. The method according to claim 1, wherein the number of silanol groups is 3.0 or less per 100 square angstroms, and the BET specific surface area is 10 or less.
A plastic Japanese musical instrument component comprising a cellulose derivative resin containing 0 to 210 m ² / g of silica and having a surface hardness of 82 or more in durometer hardness. 2. The plastic Japanese musical instrument part according to claim 1, wherein the plastic Japanese musical instrument part is any one of a shamisen repellent, a thread-wound, a piece, a kotoboshi, and a Taisho koto finger button.