JPS62115198A - Manufacture of sound wave absorbing body - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention [Summary] A relatively soft polymer is made into a sea-island state with respect to a relatively hard +A polymer, and inorganic powder particles are included in the second polymer and hardened. The present invention is designed to produce a sound wave absorber which has a certain degree of hardness and has a large attenuation of sound waves.

[Industrial application field]

The present invention relates to a sound wave absorber that is used as a structure that covers a device that generates ultrasound waves so that ultrasound waves are not radiated to the outside, or as a backing layer that is fixed to the opposite side of a transducer element from which waves are emitted. In particular, the present invention relates to a method for manufacturing a sound wave absorber in which the base material in which inorganic powder is dispersed is a mixture of a hard polymer and a soft polymer.

For example, in ultrasound probes used in ultrasound diagnostic equipment, an acoustic matching layer is generally formed on the sound wave emission side of the transducer element to match the medium of the object, and the opposite A backing layer made of a sound wave absorber is formed on the side to absorb unnecessary sound waves. In order to obtain good ultrasonic response characteristics for a sound wave absorber used in such a backing layer, the sound wave attenuation rate α must be
It is important to increase the acoustic impedance Z to optimize the conversion efficiency and pulse width of the transducer element.

Such matching of the acoustic impedance Z can be achieved by dispersing powder with a large true specific gravity such as tungsten, iron oxide, or tungsten oxide powder into a base material such as a resin.

However, in such a configuration, although it is easy to match the acoustic impedance Z, it is difficult to increase the attenuation rate α of the sound wave. Therefore, increasing the attenuation rate α of sound waves can be achieved by increasing the thickness of the backing layer, or by making the base material softer. In other words, increasing the external shape of the ultrasonic probe and making the base material softer deteriorates the machining accuracy, which is undesirable in either case.

Therefore, it is desired to increase the attenuation rate α of sound waves without increasing the thickness or softening the base material.

In this way, sound wave absorbers are generally relatively soft bodies or have air holes formed inside them, and their mechanical strength such as compressive strength and bending strength is low. When used as a structure, improvement in mechanical strength is required.

[Conventional technology]

Conventionally, it was manufactured as shown in the conventional explanatory diagram in FIG.

FIG. 4(a) is an explanatory diagram of the manufacturing process.

(b) is a sectional view of the sound wave absorber.

As shown in (a), a coating 12 of an elastic member 10 such as rubber is applied to the surface of particles of an inorganic powder 4 such as tungsten powder to form particles having a coating of the elastic member 10. Further, the particles are mixed into the resin material 11 and stirred 13.
Manufacturing was performed by dispersing the inorganic powder 4 and performing the curing step 14.

By manufacturing in this way, as shown in (b), the resin material 1
1 had a predetermined amount of inorganic powder 4 dispersed therein to form a coating of an elastic member 10.

In such a configuration, particles of the inorganic powder A are attached to the elastic member 10.
Therefore, when the sound wave indicated by the arrow AI comes into contact with the particle, its vibration energy is transmitted to two locations: the interface between the resin material 11 and the coating of the elastic member 11, and the interface between the coating and the particle. Absorbed as frictional heat.

Therefore, the reflected wave weakened by reflection is All,
Consideration is given to increasing the attenuation rate α of the sound waves that are reflected one after another as Δ12.

[Problem that the invention seeks to solve]

However, in such manufacturing, there is a limit to the amount of inorganic powder mixed in, and there is a problem in that the above-mentioned impedance Z cannot be set over a wide range.

Further, by coating each particle of the inorganic powder with an elastic member, there was a problem in that it became difficult to form the covering [9].

C: A foolproof way to solve the problem] FIG. 1 is a diagram explaining the principle of the present invention.

As shown in Figure 1, the base material has a hardness of Go J and Shore D after hardening.
a first polymer (1) having a hardness of 70 or more, and a rubber hardness Shore D after curing that is higher in hydrophobicity than the first polymer;
Form a mixture (3) with a second polymer (2) as follows, and add the inorganic powder (4) having a true specific gravity of 2 or more and a particle size of 0.3 μm to 100 μm. ) is mixed and stirred (5), and the mixture is stirred (5) and cured (6) so that the second polymer liquid (2) contains the particles of the inorganic powder (4) and becomes granular or mosaic. It was designed to let you do so.

With this configuration, the above-mentioned problems are solved.

[For production]

That is, a first polymer that becomes relatively hard after hardening is mixed with a second polymer that is more hydrophobic than the first polymer and becomes relatively soft after hardening, and an inorganic powder is added to the mixed solution. The product is manufactured by mixing and stirring to harden.

By manufacturing in this way, the second polymer can be formed into granules or mosaics relative to the first polymer, and inorganic powder can be dispersed in each granule or mosaic.

Therefore, it is possible to form a sound wave absorber having a predetermined hardness and strength and a high sound wave attenuation rate α.

〔Example〕

The present invention will be explained in detail below with reference to FIG.

FIGS. 2(a) and 2(b) are manufacturing process diagrams of an embodiment of the present invention. Like numbers refer to like objects throughout the design.

As shown in (a), an epoxy resin 20 is used as the first polymer 1, and a polybutadiene 21 modified with 10% maleic acid is used as the second polymer 2.
A mixed solution 23 is formed by mixing 20 g of polybutadiene 21 with 80 g of epoxy resin 20, and 200 g of tungsten powder 24 having a particle size of 2 μm is further mixed into this mixed solution as inorganic powder 4, followed by stirring 25. .

A heterogeneous mixture is formed by this stirring, and can be manufactured by performing curing 26.

In this case, an island of about 3 μm of polybutadiene 21 is formed inside part A, the rubber hardness Shore D is 87, and the attenuation rate of sound waves is 3.2 d13/van MHz.
becomes.

This property is based on the addition of tungsten powder to epoxy resin.
- Compared to a member that has been hardened by joining, the hardness is almost the same, and the damping rate is about twice as high.

Furthermore, in this manufacturing process, as shown in (b),
If the tungsten powder 24 is subjected to surface treatment 27 with a coupling agent such as methyltriethoxysilane solution or isopropyltriisostearoyl titanate solution before being mixed and stirred, the hydrophobicity of the powder particles will be promoted, and the volume of the cured member will be increased. Each product can be reliably dispersed with particles of tungsten powder.

Therefore, it is expected that the attenuation rate α will be further improved than in (a).

In this way, the first polymer 1 includes epoxy resin,
Acrylic resin, polyimide, diallyl phthalate resin, etc. can be used, and the rubber hardness after curing is 7.
It is sufficient if it is 0 or more.

Further, as the second polymer 2, it is possible to use the same resin material as the first polymer 1, a material having a rubber hardness Shore D of 60 or less after curing, a reactive plasticizer, rubber, etc. , polystyrene, certain silicone rubbers, etc. are also applicable.

Therefore, there are many combinations of the first and second polymers 1.2, but in each case, fractionation of minute units of 1 μm to 100 μm of the second polymer 2 occurs in the first polymer. It is important that

Through such manufacturing, it is possible to form a sea-island structure shown in the cross-sectional view of the sound wave absorber of the present invention in FIG. Sound damping can be provided by a corresponding second polymer 2.

In addition, when dispersing inorganic powder such as tungsten powder, it is easier to increase the dispersion density compared to the case of forming a conventional film, and furthermore, uniform dispersion can be achieved, which improves quality.
There is an advantage that 1- is iit.

〔Effect of the invention〕

As explained above, according to the present invention, it is possible to manufacture a material having high hardness and a high attenuation rate of sound waves.

Therefore, since mechanical strength is obtained, it is possible to use it as a structure, and it is possible to improve workability, and furthermore, it is possible to obtain a low-cost and high-quality sound wave absorber, and the practical effect is It's large.

[Brief explanation of drawings]

FIG. 1 is a detailed explanatory diagram of the present invention. FIGS. 2(a) and 2(b) are manufacturing process diagrams of an embodiment of the present invention. FIG. 3 is a sectional view of the sound wave absorber of the present invention. FIG. 4 is an explanatory diagram of the conventional method, and (a) is an explanatory diagram of the manufacturing process.
(b) shows a cross-sectional view of the sound wave absorber. In the figure, j is the first polymer, and 2 is the second polymer. 3 is a mixture, 4 is an inorganic powder. 5 is mixing and stirring, 6 is curing. 7 indicates surface treatment. Agent Patent Attorney Sada Igeta - $i
Day, q's 5th day of the month, 5th month] Figure j (b) 4th day, month Lf) 15B4 meditated Σq, t-, cross section 2, 3rd figure, neck of the board AAA figure

Claims (1)

[Scope of Claims] [1] A method for producing a sound wave absorber that is formed by dispersing a predetermined amount of inorganic powder in a base material and that attenuates the propagation of ultrasonic waves, wherein the base material has a rubber hardness after curing. A mixture (3) of a first polymer (1) having a shore D of 70 or more and a second polymer (2) having a rubber hardness shore D of 60 or less after curing and which is more hydrophobic than the first polymer. ), and the mixture (3) has a true specific gravity of 2 or more and a particle size of 0.
Mix and stir the inorganic powder (4) of 3 μm to 100 μm (
5), and after the mixing and stirring (5), the second polymer (2) includes the particles of the inorganic powder (4) and is cured (6) so that it becomes granular or mosaic-like. Method for manufacturing a sound wave absorber. [2] The inorganic powder (4) is surface treated with a silanol coupling agent and a titanate coupling agent (7).
) The method for manufacturing a sound wave absorber according to claim 1, wherein