| 摘要 |
<p>PURPOSE: To improve quality while using easily available and inexpensive timber by constituting the above bridge of a wooden material which contains a silicone resin and having a resin content of a specific value. CONSTITUTION: This bridge consists of the wooden material which contains the silicone resin and the contains this resin at 1 to 30wt.%. Only the inside of vessels or both of the vessels 5 and cell walls 6 are impregnated with the silicone resin. The content of the silicone resin, i.e., the ratio of the silicone resin to the total sum of the wooden material and the silicone resin, is preferably specified to l to 30wt.%. The more preferable ratio is 5 to 10wt.%. The reason thereof lies in that the effect of incorporation of the silicone resin into the timber and more particularly the improvement in surface hardness and modulus of elasticity are insufficient if the ratio is below 1wt.%. There is a tendency that the rise of tones of a piano is poor if E/ρwhich is an index for the propagation speed of the longitudinal waves in the material decreases. The value of E/ρis adequately 1.45 to 1.7×10<7> m<2> s<-2> and <=30wt.% is more preferable to suppress the excessive increase of the density. E denotes a Young's modulus andρdenotes the density.</p> |
