JPS6386752A - Keyboard - Google Patents

Abstract

PURPOSE:To obtain the title keyboard by applying a surface material, prepared by containing a specific hydrous inorganic filler in a specific amount in a casein resin matrix cured with formalin and having characteristics extremely resembling those of ivory. CONSTITUTION:A keyboard obtained by blending 100pts.wt. casein resin matrix, pulverized to a particle size of <=100mesh and having 75,000-375,000mol.wt. with 10-75pts.wt. hydrous inorganic filler selected from the group consisting of aluminum hydroxide, calcium sulfate hydrate, hydrous calcium silicate, etc., molding the resultant blend, treating the molded article with formalin and applying the obtained thin plate onto a keying part of a keyboard substrate consisting of wood.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a keyboard to which a surface material having properties very similar to ivory is attached.

[Conventional technology]

Ivory is highly valued by experts as a material that makes up at least the surface of the keys of keyboard instruments such as pianos, organs, and accordions. This is thought to be due to the fact that ivory ideally satisfies the following characteristics required as a keyboard material, rather than the fact that it 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 white bark, it has 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) Possess appropriate workability.

[Problem that the invention seeks to solve]

However, natural ivory, which has such excellent properties, has the disadvantage that demand cannot be met due to insufficient supply capacity. Particularly in recent years, African countries that produce the fish have begun banning their capture for animal welfare reasons, and the imbalance between supply and demand is even more significant.

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, their surfaces are too smooth, making it easy for fingers to slip on them, and their lack of water absorption makes them especially slippery when sweating, which can lead to mis-touching. This caused some inconvenience. Furthermore, since the hardness is generally insufficient, wear during long-term use also becomes a problem.

This invention provides a keyboard with an ivory-like surface material affixed with casein as a matrix resin, which, like ivory, satisfies various required characteristics as a keyboard material and solves the problem of supply. be.

[Means for Solving the Problems] The method of kneading casein to which pigments or dyes have been added with water, molding, and hardening by formalin treatment is itself known as a method for manufacturing casein plastics.

However, there are problems with using such casein plastic as it is as a keyboard material. That is, such casein plastic does not have the feel, dimensional stability when dry and wet, hardness, thermal conductivity, and heavy feel that ivory as a keyboard material has. This invention uses casein as a matrix resin and blends a water-containing inorganic filler in a specific ratio, thereby taking advantage of the great water absorbency and compatibility with the human body (finger, etc.) of casein plastic, while solving the above-mentioned drawbacks. This work was completed based on the knowledge that a surface material with properties dramatically similar to those of ivory was obtained, and that an excellent keyboard could be obtained by attaching this material to a wood keyboard base material. That is, the keyboard of the present invention contains aluminum hydroxide, calcium sulfate hydrate, hydrated calcium silicate, hydrated aluminum silicate, hydrated magnesium silicate, and hydrated silicate in 100 parts by weight of a casein resin matrix hardened with formalin. A thin plate comprising 10 to 75 parts by weight of a specific water-containing inorganic filler selected from the group consisting of: be.

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

The casein used in this invention needs to be a fine powder, preferably pulverized to 100 mesh or less. This is because if the casein is coarse, it will not be mixed uniformly with the filler. Casein belongs to phosphoproteins and is a mixture of mutually similar proteins (complex protein).
The molecular weight is about 75,000 to 375,000, and there are about 3
%, about 1% is contained in human milk. Among these, rennet casein is obtained mainly from milk by coagulating it with the enzyme rennin, and acid casein is obtained by coagulating it with acid. For the purposes of the present invention, the use of rennet casein, which has a folded and highly branched macromolecular structure, is particularly suitable.

In the present invention, the term "hydrous inorganic filler" refers to an inorganic filler that has adsorption or water of crystallization itself, or that is easily hydrated with water to contain water of crystallization, such as aluminum hydroxide, aluminum hydroxide, Those selected from calcium sulfate hydrate, hydrated calcium silicate, hydrated aluminum silicate, hydrated magnesium silicate, and hydrated silicic acid are used.

These hydrous inorganic fillers are added at a ratio of 10 to 75 parts per 100 parts of casein.

If it is less than 10 parts, the effect of addition is not sufficient. On the other hand, when more than 75 parts are added, the tensile strength and elongation at break of the surface material obtained sharply decrease, and the tensile Young's modulus sharply increases. For this reason, the surface material cannot follow the dimensional changes due to expansion and contraction of the wood, resulting in cracking and peeling of the surface material.

The present invention addresses the requirements for suitability as a keyboard surface material, the manufacturing process requirement of applying an adhesive onto a wood key base material, and the integrity with the base material water required when used as a keyboard. In view of the requirements, 10 to 75 parts by weight of filler is used per 100 parts by weight of casein (filler content in the composition is 9 to 43 Ifi 1%).

Incidentally, Fig. 1 shows the rate of change in dimensions (solid line) corresponding to the rate of decrease in water content using the filler content of filler-containing casein plastic as a parameter, in the direction parallel to the annual rings of the wood key base material to which it is attached ( It is shown in a graph along with a similar dimensional change rate range (dotted line) due to drying in the T direction). In this way, in the process of attaching a surface material made of a casein plastic molded body to wood using an adhesive and drying it as in the present invention, the shrinkage rate of the surface material must be equal to or smaller than that of wood. Cracking of the surface material occurs, and for this purpose a filler content of 25% or more is particularly desirable.

On the other hand, changes in physical properties due to changes in the filler content of casein plastic are shown in the attached Figure 2, and the tensile elongation (curve a) that occurs in the region where the filler content exceeds 43%
The decrease in tensile strength (curve b) and the increase in Young's modulus (curve C) both result in the surface material not being able to follow the dimensional changes caused by the absorption and drainage of the wood base material in the keyboard material of the pasted structure, and as a result, the surface material This means that it may lead to cracking or destruction.

Therefore, in order to obtain a keyboard material with a stable pasting structure, the filler content range of the present invention is extremely critical.

Next, FIG. 3 shows the relationship between the immersion time in water and the water absorption rate, using the filler content of the filler-containing casein plastic as a parameter. Using ivory 25 x 25 x 1.5 mm thick and casein composite molded plate 25 x 25 x 1.5 mm thick as samples, a water absorption test was conducted on both from an absolutely dry state.

The water temperature was 23°C. According to this, the water absorption rate of the filler-containing plastic of the present invention changes depending on the content of the filler, and the value of the water absorption rate characteristic of ivory, which is the target of the present invention, is within the content range of the filler of the present invention. It turns out that it is almost included in

Similarly, FIG. 4 shows the relationship between filler content and thermal conductivity of filler-containing casein plastics.

Two samples measuring 50 x 50 x 30 m were used, and a thermal conductivity measuring device manufactured by Kyoto Electronics Industry Co., Ltd. was used as the apparatus.

Natural ivory has a water content of 3 to 12% and its thermal conductivity varies. According to this, the lower limit of the filler content of the present invention is 10%.
The above shows that properties corresponding to the thermal conductivity properties of ivory can be obtained in filler-containing casein plastic.

Therefore, it turns out that the filler content range of the present invention is extremely critical for the water absorption and thermal conductivity properties as well as for the shrinkage rate mentioned above.

In addition to the above ingredients, the raw material formulation also contains casein 10
To 0 parts, 1 to 10 parts of a pigment acidic dye such as titanium oxide (if titanium oxide is not used as a filler) or zinc white can be added as a pigment in order to adjust the color tone.

For example, add each of the above components at 10 parts per 100 parts of casein.
Knead with ~40 parts of water using a crusher or the like.

After this kneading, it is preferable to leave the mixture at room temperature for about 5 to 24 hours to expand the casein and improve subsequent moldability.

Next, the mixture is molded, and the molding can be performed by extrusion, post-roll pressing, pressing, or other methods. Extrusion molding is performed at a pressure of about 100 to 200 kg/cd and a pressure of about 20 to 200 kg/cd.
It is carried out in a temperature range of about 100°C with an increasing temperature gradient from the base of the cylinder of the extruder to the die. Press molding is preferably performed at a pressure of 100 to 200 kg/cj and a temperature of 8
It is carried out under conditions ranging from 5 to 95°C.

Next, the molded body is immersed in formalin having a concentration of about 3 to 10 parts 6 at around room temperature to harden the casein. The immersion time varies depending on the dimensions of the molded product, but in the case of a plate-like product, for example, 60 days for a 3II11 thickness, 16 days for a 5 mm thickness, 10
It is about 50 mouths in m1.

A surface material is obtained by drying the molded cured product on a hot surface at a temperature of about 20 to 45° C., and further performing post-processing such as cutting, cutting, and polishing as necessary. The keyboard material of the present invention can be obtained by attaching the surface material thus obtained to the key-pressing portion of the surface of a key base material made of wood. The keyboard material according to the present invention can be used as a black key (material) by coloring, but more preferably, it can be used as a white key (material) like ivory.

[Action and effect of the invention]

As described above, according to the present invention, a key surface material very similar to natural ivory obtained by kneading powdered casein and a water-containing inorganic filler with water and hardening it by formalin treatment after molding is used as a wooden key. By attaching it to a base material, an excellent keyboard material can be obtained.

The resulting keyboard material has the following characteristics in particular.

(b) The surface material exhibits high water absorption of approximately 10% when immersed in water at 25°C for 24 hours, so it sufficiently absorbs sweat from fingers during performance and prevents mis-touching due to slipping during sweating.

(b) The surface material has a feel, weight, and texture comparable to natural ivory.
It has a coefficient of friction.

(c) The surface material can be molded by changing the blending ratio of pigments or dyes during or after its formation, or it can be piece-dyed with dyes to give it a free pattern.

(d) The surface material has high dimensional stability during dry and wet conditions and excellent physical properties. Therefore, there is no inconvenience such as cracking or peeling of the surface material when manufacturing a keyboard material by pasting it onto a wood key base material and drying it, as well as during subsequent use.

〔Example〕

An example of molding the surface material will be described below.

Example Ruinette casein (particle size: 150-250 mesh) 100 parts water
30 parts Titanium oxide 5 parts Aluminum hydroxide 50 parts The above ingredients were sufficiently kneaded in a grinder and left at room temperature for 12 hours to swell the casein. This mixture was filled into a mold and molded using a heat press machine at 95°C and 150 kg/c, and then hardened with a 5% formalin solution to give a homogeneous ivory color of 50 x 200 x 5
A molded body of the fin was obtained. When various properties required for a keyboard were measured for this molded body, the following results were obtained.

Specific gravity 1.58 Hardness Hr (M) 70~80 (
20℃, 60%) Hr (M) 40~50 (immersed in water at 25℃ for 24 hours) This Rockwell hardness (M scale) is a constant result of water absorption.
Rate 6-10% (immersed in 25°C water for 24 hours) Bending strength 7-8 kg/si Bending modulus 500-600) cg/i Thermal conductivity 0
．． 5 kcal/m, hr, 'C Coefficient of static friction Dry state 0, 95 to 1.00 Compressive strength 30 to 40 kg/m In addition, for a molded body molded in the same manner except for aluminum hydroxide from the above raw materials, the following results are obtained. was gotten.

Specific gravity 1.34 Hardness Hr (M)”) 9 (20℃ 6
0%) Hr (M) 16 (after immersion in water at 25°C) Bending strength 7-8 kg/ttti Flexural modulus 5
00 to 600 kg/i Compressive strength 19 to 30 kg/mtA Tensile strength 7 kg/d Static friction coefficient Dry state 0.80 to 0.90 Thermal conductivity 0.18 kcal/m, hr, Example 2 The composition of Example 1 and In comparison, all molding methods were carried out with the same dimensions except that the type of filler was changed to each of the fillers listed in Table 1 below to obtain molded bodies.

The results show that various fillers are approximately equally effective for the present invention.

[Brief explanation of the drawing]

Figure 1 is a graph showing the relationship between the rate of decrease in water content and the rate of change in wood dimensions using the filler content of filler-containing carbon plastic as a parameter. Figure 2 is a graph showing the change in filler content and various physical properties of casein plastic. Figure 3 is a graph showing the relationship between immersion time in water and water absorption of ivory and casein composite molded plates. Figure 4 is the graph showing the relationship between filler content and thermal conductivity of casein plastic containing filler. It is a graph showing the relationship. Applicant's representative Mr. Sato o5 10 Reduction rate of water content (%) Figure 1 Figure 2 1 hour of immersion in water (Hr) Figure 3

Claims (1)

[Claims] 1. In 100 parts by weight of a casein resin matrix hardened with formalin, aluminum hydroxide, calcium sulfate hydrate, hydrated calcium silicate, hydrated aluminum silicate, hydrated magnesium silicate, and hydrated silicate are added. A keyboard comprising a thin plate containing 10 to 75 parts by weight of a water-containing inorganic filler selected from the group consisting of acids dispersed therein and pasted onto the key-pressing part of a key base material made of wood. 2. The keyboard according to claim 1, wherein the inorganic filler is a hydrous inorganic filler selected from the group consisting of aluminum hydroxide, calcium sulfate hydrate, and hydrous silicic acid.