JPH0333493B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for producing a keyboard material having a pattern and properties very similar to ivory, which has excellent properties as a keyboard material for a keyboard instrument.

(Prior Art) Ivory is highly valued by experts as a material constituting at least the surface of the keys of keyboard instruments such as pianos, organs, and accordions. This is thought to be because ivory ideally satisfies the following characteristics required as a keyboard material, rather than because ivory is originally a high-quality art material.

(a) Must have appropriate water absorption. This is required to absorb sweat from the player's fingers and prevent slippage due to sweat.

(b) It must have appropriate surface smoothness and friction coefficient. This affects the tactile sensation when pressing a key.

(c) It has an excellent appearance (despite its high whiteness,
(Excellent stain resistance).

(d) Must have appropriate hardness. This is required to provide a tactile feel when pressing keys and to prevent wear due to long-term use.

(E) Must have appropriate workability.

However, natural ivory, which has such excellent properties, has the disadvantage that demand cannot be met due to insufficient supply capacity.

In view of these circumstances, synthetic resins are widely used as keyboard materials because they generally have no problems in terms of supply. However, although synthetic resin keyboards are somewhat satisfactory in terms of appearance and workability, the surface is too smooth, making it easy for fingers to slip on them, and because they lack water absorption, they become especially slippery when sweating, making it difficult to make mistakes. This caused some inconvenience. Furthermore, since the hardness is generally insufficient, wear during long-term use also becomes a problem.

In order to eliminate the disadvantages of the above-mentioned synthetic resin keyboard materials, the present inventor has already proposed an ivory-like keyboard material made of casein plastic mixed with a hydrous or non-hydrus inorganic filler. (Unexamined Japanese Patent Publication 1987)
-45592 and 57-96046). Such filler-containing casein plastics are produced by kneading casein with a filler and water, molding, and then impregnating with formalin and hardening. The above technology has the advantage of casein plastic, which is a molded body of natural protein molding material.
While taking advantage of the characteristics of high water absorption and compatibility with the human body (finger etc.), the disadvantages of inferior hardness, thermal conductivity, heavy texture, etc. compared to ivory are eliminated by blending inorganic fillers. It is believed that this provides an ivory keyboard material with superior properties compared to conventional synthetic resin keyboard materials.

(Problems to be Solved by the Invention) However, when the above-mentioned filler-containing casein plastic is compared with natural ivory material,
There are still some deficiencies in aesthetics and realism. This is because the filler-containing casein plastic described above has a single appearance and cannot reproduce the annual ring pattern of natural ivory, that is, the flowing striped pattern that extends to the interior and is similar to the grain of wood.

On the other hand, multi-colored casein molding compositions have been co-extruded using a multi-cylinder extruder to form multi-colored patterns, but simple multi-colored extrusion molding is difficult due to the subtle differences between the interfaces of natural ivory. No flow pattern is formed.

In view of the above-mentioned points, it is an object of the present invention to provide an ivory-like keyboard material that has a flowing striped pattern that extends to the inside and has a more realistic feel.

(Means for Solving the Problems) As a result of research for the above-mentioned purpose, the present inventor has determined that at least one of two or more filler-containing casein compositions having different color tones can be used in the form of strings, threads, or bands. After arranging the entire sheet-like structure together with other compositions, the resulting sheet-like arrangement is heated and pressed to form stripes with a flow that extends to the interior, which is seen in natural ivory. We have found that this method is extremely effective for reproducing geometric patterns.

The method for producing an ivory-like keyboard material of the present invention is based on the above-mentioned knowledge, and more specifically, the method involves kneading two or more types of casein with different color tones and water contents by kneading casein with a filler and water. A composition is prepared and, for example, by two-color extrusion molding, these compositions are formed into strips to form a sheet-like array in which striped compositions of different colors and water contents are alternately arranged. The arrangement is characterized by hot pressing the array in a direction perpendicular to its surface to fluidize these compositions to form an integral sheet-like molded body, and impregnating the obtained sheet-like molded body with formalin and hardening it. It is something.

This invention will be explained in more detail below. In the following description, "%" and "part" are based on weight unless otherwise specified.

In the method of the present invention, casein is kneaded with a filler, water, and a coloring agent added as necessary to obtain two or more types of molding compositions that differ from each other in color tone and water content.

As casein, fine powder of rennet casein pulverized to 100 mesh or less is preferably used.

The type of filler is basically not limited, but
To provide an ivory-like keyboard material, preferably
Hydrous inorganics such as aluminum hydroxide or alumina hydrate, calcium sulfate hydrate, hydrated calcium silicate, calcium hydroxide, magnesium hydroxide, basic magnesium carbonate, hydrated aluminum silicate, magnesium silicate, hydrated silicic acid, etc. Fillers, or silicon oxide, calcium phosphate,
Inorganic fillers such as non-hydrous inorganic fillers such as alumina, calcium carbonate, barium carbonate, calcium sulfate, magnesium oxide, and titanium oxide are used. These fillers are based on 100 parts of casein.
It is used in proportions of 10 to 200 parts, preferably 25 to 85 parts.

In addition to the above-mentioned components, the molding composition further includes pigments such as titanium oxide and zinc white in a proportion of 0 to 10 parts, particularly 1 to 5 parts, per 100 parts of casein, in order to adjust the color tone. Alternatively, a coloring agent such as an acid dye is added.

Add 20 to 80 parts of each of the above ingredients to 100 parts of casein.
Particularly, 20 to 50 parts of water are kneaded using a grinder or the like. After kneading, it is preferable to leave the mixture at room temperature for about 5 to 24 hours to swell the casein and improve subsequent moldability.

Individual molding compositions are obtained by the above operations, and two or more types of molding compositions can be obtained by repeating this process, but the difference in color tone between the compositions is due to the amount of filler or colorant blended. given by change. However, if the amount of filler blended differs greatly between compositions, the properties such as dimensional change rate will differ partially in the cured product, which may cause cracking or peeling at the interface. The difference in the blended amount of fillers including casein 100
It is preferable to limit the amount to 10 parts or less.
Differences in color tone are preferably provided by varying the amount of colorant by 0.1 to 2 parts.

Next, an embodiment of producing an ivory-like keyboard material according to the present invention from two or more types of molding-like compositions will be described.

In this specification, the term "stripe body" is used to include thread-like bodies, string-like bodies, band-like bodies, and rod-like bodies.

These two types of molding compositions are formed and arranged alternately to obtain a sheet-like array. For this purpose, two types of striped compositions extruded from appropriate nozzles can be alternately arranged.
In the method of the present invention, a sheet-like array can be obtained by multicolor extrusion molding, for example, two-color extrusion molding, in which striping of each composition and alternating arrangement thereof are performed simultaneously or sequentially. This is because the plasticizer for casein molding is water, and since the molding is carried out at a high temperature close to the boiling point of water, extrusion molding is preferable since it can avoid evaporation of water.

In this case, as shown in FIG. 1, which is a plane axial cross-sectional view of the two extruders (also showing the typical temperature distribution of each part), the A raw material composition is Input the material and start the second extruder 1.
The B raw material composition is introduced from the upstream side B direction of 2, and two-color extrusion is performed from the mixing extrusion section 13. A partial cross-sectional view of the mixing section 13 seen from the diagonal front side of the mold is as shown in FIG.
As shown in FIG. 4, which is an X-sectional view, a sheet-like array 31 having a thickness of, for example, 1 to 2 mm and in which striped compositions A ₂ and B ₂ are alternately arranged is obtained.

Next, the sheet-like array 31 thus obtained is sandwiched between a pair of hot plates and heated and pressurized, thereby creating a sharp gap between the striped compositions A ₂ and B ₂ in the sheet-like array 31. A sheet-like molded product having a disturbed interface and a flow pattern 51 as shown in FIG. 5 is obtained. This heat-pressure process is performed, for example, at a temperature of 80-95℃ and a pressure of 100-150Kg/ ^cm2 for 15-30℃.
This is done by holding a minute.

FIG. 6 and FIG. 7 are for explaining one preferable embodiment of hot pressing, and the sheet-like array 31 obtained as described above is arranged in several sheets (in this example, four sheets) in the horizontal direction as necessary. The sheets are lined up, and the whole is surrounded by a rigid wall that is slightly thinner than the sheet-like array body 31 to prevent leakage, and the upper and lower surfaces are sandwiched between releasable sheets such as polyester sheets. Heat and pressure treatment as described above is performed. As a result, the sheet-like array 31 is crushed as a whole, and a turbulent or flowing pattern is generated at the interface between the striated compositions A ₂ and B ₂ . At this time, a flow of the composition occurs on the surface of the sheet-like array 31, and the flow is particularly large on the surface near the edges, so that a part of the pattern disappears. However, even in such an end portion, there is no problem because the pattern emerges from the inside through the polishing process when finishing the keyboard from the obtained material.

In addition, when forming a sheet-like array by two-color extrusion, as shown in FIG. 9 corresponding to FIG. 4, by changing the shape of the mold, the striped compositions A ₂ and B It is also preferable to make one of _{the two} (B ₂ in this example) 10-20% thicker than the other to form the protrusion. Such protrusions of the sheet-like array 32 are crushed in a heat-pressing process and smoothed by increasing the width of the composition _B2 , but at this time,
A flowing or turbulent pattern is effectively generated at the interface between compositions A ₂ and B ₂ . At this time, in order to suppress the fluidity of the strip composition to be projected during the heat-pressing process, the following means (a) to (c) can also be adopted.

(a) The water content of composition A ₂ is made higher than that of composition B ₂ . The difference in water content is preferably 20 parts or more, particularly 30 parts or more, based on 100 parts of casein. In addition, it is preferable that the water content in one of the compositions is higher than that of a conventional casein plastic molding composition in this way, in order to increase the adhesion between the two compositions.

(b) The temperature of the hot plate in contact with composition B ₂ is set at 80 to 85°C.
The temperature of the hot plate in contact with composition A ₂ is set at 90 to 95 °C, with a temperature difference of about 5 to 10 °C between the two to facilitate plasticization of composition A ₂ .

Composition A ₂ is brought into contact with the hot plate about 3 to 5 minutes earlier than composition B ₂ is brought into contact with the hot plate.

The difference in fluidity between compositions as described above can also be achieved by varying the amount of filler blended.

Next, the sheet-like molded product obtained as described above is subjected to formalin hardening treatment, but before that, if necessary, the molded product is dried with hot air at 50 to 80°C to reduce the moisture content to 0 to 5%. It is preferable to keep it. This is because if the water content of the molded product before formalin treatment is high, the dimensional stability of the cured product will decrease, especially in a high humidity atmosphere.

Next, the thus dried molded body is immersed in about 3 to 10% formalin at around room temperature to harden the casein. The immersion time varies depending on the dimensions of the molded object, but in the case of a plate-like object, an example is
days. 5mm is 16 days, 10mm is about 50 days.

The molded cured product is first air-dried to reduce the moisture content to about 10%, and then dried at a temperature of 20 to 45°C for 2 to 5 days to bring the moisture content to 4 to 6%. If deformation occurs, put it in boiling water for a few minutes, heat it, pressurize it at low pressure, and then dry it again at 30-40°C to adjust the moisture content to 3-4%. do. Further, if necessary, the keyboard material according to the present invention can be obtained by performing post-processing such as cutting, cutting, polishing, etc.

In the above explanation, an example using two types of molding compositions has been described, but it will be easily understood that the above method can be carried out using three or more types of molding compositions.

The keyboard material according to the present invention obtained as described above can be the key itself or a key surface material composited with other materials; in the latter case, the key base material is mainly made of wood or the like. It is attached to the keypad on the surface of the keyboard.

〔Effect of the invention〕

As described above, according to the present invention, two or more types of filler-containing casein molding compositions having different color tones and water contents are alternately arranged to form a sheet-like array, and this sheet By heat-pressing the shaped array and then curing it, a keyboard material having a flowing striped pattern extending to the interior and having a texture extremely similar to natural ivory can be obtained.

[Brief explanation of drawings]

1 to 9 are explanatory diagrams of the manufacturing process of a keyboard material according to the method of the present invention, in which FIG. 1 is a plan axial cross-sectional view, and FIG. 3 and 4 are respectively a plan view and a sectional view of the sheet-like array;
Figure 5 is a cross-sectional view of the sheet-like molded product after hot pressing, Figure 6
Figures 9 to 8 are explanatory diagrams of other aspects of the heat-pressing process, and Figure 9
The figure is a sectional view of another example of a sheet-like array. 31, 32... sheet-like array, 41, 42...
...Sheet-shaped molded body, 6... Rigid frame, 7... Mold release sheet, A, B... Molding composition (subscripts 1, 2
(means sheeted and striated, respectively).

Claims (1)

[Claims] 1 Prepare two or more compositions with different color tones and water contents made by kneading casein with a filler and water, and form each of these compositions into strips by extrusion molding. A sheet-like array is formed by alternately arranging compositions with different amounts of water, and this sheet-like array is hot-pressed in a direction perpendicular to the surface of the sheet-like array to fluidize these compositions and form an integral sheet-like molded body. A method for producing an ivory-like keyboard material having a flowing striped pattern, characterized by impregnating the obtained sheet-like molded body with formalin and curing it.