JPS6289765A - Silicone rubber composition for use in acoustic medium - Google Patents

Abstract

PURPOSE:To obtain the titled composition good in balance among sound velocity, acoustic impedance and ultrasonically damping level, by incorporating an organopolysiloxane containing halogen-substituted alkyl group with high-density inorganic powder and/or metallic powder and crosslinking agent and/or curing catalyst. CONSTITUTION:The objective composition for use in ultrasonically echographic devices can be obtained by incorporating (A) 100pts.wt. of an organopolysiloxane containing halogen-substituted alkyl group (also may contain reactive group such as vinyl group depending on the crosslinking scheme or non-substituted organic group) with (B) 10-200pts.wt. of inorganic metallic oxide powder (e.g., silica, titanium dioxide) and/or metallic powder (e.g., of iron, zinc) with an average particle size 0.1-1mum and density >=2g/cm<3> and (C) a crosslinking agent (e.g., alkoxysilane, alkoxysiloxane) and/or curing catalyst (e.g., organic peroxide, platinum compound) depending on the curing scheme.

Description

[Detailed Description of the Invention] [Industrial Field of Application] The present invention is applicable to acoustic media used in ultrasonic diagnostic equipment, particularly at the speed of sound. :Keep the acoustic impedance below 1500m/see, bring the acoustic impedance closer to the living body, and have a low ultrasonic attenuation rate in the high frequency range, so it can be used as a phantom, a warm bag, or an acoustic lens for high-resolution ultrasonic probes. This invention relates to silicone rubber that can be used.

[Prior art]

For example, the acoustic lens of the ultrasonic diagnostic probe is designed to focus ultrasonic waves, adhere well to the living body, and reduce the reflection of ultrasonic waves at the interface with the living body, and the ultrasonic waves of the lens itself The damping rate is small and the mechanical strength g is large.
Since chemical stability is an essential condition, silicone rubber is used, which is made by adding inorganic fillers such as phosphoric acid, alumina, and titanium oxide to dimethylpolysiloxane.

Conventionally, the silicone rubber used for this type of application is 1.
Dimethylpolysiloxane has a density of 0.95 to 1.00. Since the speed of sound is approximately 1000 m/sec, its acoustic impedance (sound velocity
They cannot be used alone because of the large differences between them.

Therefore, by increasing the density of the silicone rubber composition by adding high-density inorganic fillers, etc., the acoustic impedance of the silicone rubber composition has been brought close to that of the living body. filler required”
'C, and in this case, the ultrasonic attenuation value of the acoustic lens becomes significantly large, resulting in a disadvantage that the quantity in the 1st satellite frequency range decreases.

Ultimately, no material with a good balance of sound velocity, acoustic impedance, and ultrasonic attenuation has been obtained to date.

[Structure of the invention]

The inventors of the present invention have conducted extensive research on the Group I components of this ultrasonic diagnostic apparatus in order to provide an acoustic medium that overcomes the disadvantages of the conventional apparatus. Specifically, the purpose of the present invention is to maintain the speed of sound at 1500 m/see or less, and
To provide a silicone rubber composition in which the acoustic impedance is controlled to a value close to 9/-sec to 1.4 to 1.6X 10', which is the acoustic impedance of a living body, and the ultrasonic range mt is kept small. be.

/# In the patent publication No. 56-168547, did Funon-based silicone rubber, which has a lower sound velocity than in living bodies, be used as an fW lens? 11 are listed.

This fluorine-based silicone rubber is characterized by the fact that it has a large amount of attenuation compared to conventional silicone rubber, and eliminates multita echoes. By using an organopolysiloxane/organopolysiloxane containing a substituted alkyl group as the main component, the specific gravity can be increased with the addition of a significantly smaller amount of filler than when dimenal polysiloxane is used. In a halogen-substituted alkyl-containing organopolysiloxane composition, the change in physical properties due to temperature is greater, in order to avoid negative effects such as an increase in ultrasonic attenuation caused by adding a multivalued agent -fD''. We have completed the present invention by discovering that at a temperature of 35° C., which is closer to that of a living body and is used for smiling, than the room temperature of 25° C., a preferable value closer to the acoustic characteristics of a living body can be obtained.

Each component of the composition of the present invention will be explained in detail.

Silicone rubber composition according to the present invention ■ 100 parts by weight of organopolysiloxane containing a halogen-substituted alkyl group @ Density 2.0 with an average particle size of 0.1 to 1.0 μm
Inorganic powder of 910d or more and metal powder 10
~200 parts.

O crosslinking agent and/or curing catalyst, in which the halogen-substituted alkyl group is FI C'I
Br, a monovalent alkyl group substituted with at least 1 mole of halogen atom of I, for example, -CHJ',
-CHFt, -CFs, -CHtCHtF,
-CHzCHFt.

-CHtCFs, -CRFCFs, -CHtCH
tCHtF.

-CHICLCHF, -CM,CH,CF,
, -CH, CL, -CHC lambda key cHtcf(tcHtcz, -CH2Br, -C
A group such as HtI is suitable. In addition, in the organopolysiloxane of the present invention, in addition to these halogen-substituted alkyl groups, non-fill organic groups such as J-thyl, x-thyl, propyl, and phenyl can also be used in combination. Here, The organopolysiloxane of the present invention is
Substantially, RX RX R31-0,
5i-0,81-070 gisan units +
1 1Rx 几
It is a copolymer consisting of R and containing at least Rx. The organopolysiloxane can be used in a normal state from a low viscosity liquid to a high degree of polymerization raw rubber, and the composition of the present invention can be in the form of either a liquid rubber suitable for injection molding or a rubber compact for pressure molding. be able to. or,
In the organic groups of the organopolysiloxane, reactive groups such as vinyl groups and alkoxy groups are present in necessary amounts depending on the respective crosslinking method.

Secondly, as the filler mixed in the organopolysiloxane, the present invention has the effect of adopting an organopolysiloxane containing a rogane-substituted alkyl group, which has a high density.
Although the required mixing amount is smaller than in the case of conventional dimethylpolysiloxane systems, it is still an important and essential component.

In the present invention, unlike the purpose of ordinary fillers such as reinforcement and bulking, the role of adjusting the density of the rubber and, as a result, adjusting the acoustic impedance, is compatible with the main component organopolysiloxane. For example, silica, titanium oxide, alumina, metal oxides such as iron oxide, iron, zinc, aluminum, etc. are selected from high-density inorganic powders and metal powders.These powders are used to make silicone rubber. On the other hand, there are four types that have been previously subjected to surface treatment to improve dispersion.

Dicumyl peroxide,
A method using an organic peroxide such as dichlorobenzoyl peroxide, a method using an addition reaction using a platinum compound,
Condensation methods using condensation catalysts such as dealcoholization and dealtoning, and methods using energy ItA such as ultraviolet rays are known, and in the present invention, any of them can be used, and there are no limitations. do not have. Therefore,
As the crosslinking agent and curing catalyst, curing catalysts such as organic peroxides, platinum compounds, and organic acid salts of metals, and crosslinking agents such as hydrogen-containing siloxanes, alkoxysilanes, and alkoxysiloxanes can be used depending on the respective curing method.

Example 1 Both ends of the molecular chain are blocked with dimethylvinyl groups, and r is attached to the side chain.
-) has 35 mol/Sr methyl group/65 mol/) of refluoropropyl groups, and has a viscosity of 300Q at 25°C.
50 parts by weight of titanium oxide CR-93 (5 Hara Sangyo ■) with an average particle diameter of 0.3 μm in 100 parts by weight of diorganopolysiloxane, which is cp, and 20 m of hydrogen groups at the terminal and side chains.
o l / * * 3 parts by weight of diorganohydrodiene siloxane having 30 mol/L of r-fluoropropyl groups in the side chain and 50 mol/f' of methyl groups,
0.1 parts by weight of a 1-methanol solution of chloroplatinic acid was mixed until homogeneous, and press-molded at 150°C for 10 minutes for 5r.
A sheet with a thickness of rrn was prepared. What are the acoustic characteristics of this sheet? Upon investigation, we found the following results suitable for acoustic lenses for probes.

Density 1.58 sound velocity (m/5
ee) 20℃ 98135℃ 936 Acoustic impedance 20℃ 1.55x 1 d'
M/+/・5ec35℃ 1.49 X 1♂'9/d
- sea attenuation dB/rrrn 20°C 2.1 (frequency 3.5MHz) 35°C 1.8 Example 2 Dichloromethyl containing 0.2 mol/- of vinyl groups (
100 parts by weight of polysiloxa/raw rubber, 0.5 parts by weight of a mixture of 70 parts by weight of alumina with an average particle size of 0.5 μm were added, press-molded at 180°C for 10 minutes, and then post-molded at 180°C for 1 hour. ? Air, thickness 5mm
A sheet was formed. When the acoustic properties of this sheet were investigated, the following properties were found to be suitable for an acoustic lens for a probe.

Density 1.65 sound speed m/
see 20℃ 97535℃ 941 Acoustic impedance 20℃ 1.59 X 10Sk
j/d ・5ee35℃ 1.51 Attenuation dB/■ 20℃ 2.0 (Frequency 3.5 MH7) 35℃ 1.7 Comparative example (
Conventional example) A sheet with a thickness of 5 snow was prepared in the same manner as in Example 2 by mixing 100 parts of dimethylpolysiloxane raw rubber containing 90.2 mol of vinyl groups with 0 parts of aluminum cuff having an average particle diameter of 0.5 μm. Molded. Also, l't3j same alumina ft
Even when 150 parts by weight was mixed, insufficient results were produced in either of the decay rates.

Aluminum + 70 parts by weight Adhesive 150 parts by weight
Degree 1.35 1.73 Speed of sound m/sec 20℃ 930 84935
℃ 892 810 tone blue impedance 20℃ 1.22x 10' 1.47xl
O'1.19X 10'1.43X10' Attenuation rate dB/Tsuru 25℃ 2.0 3.51.9
3.4 [Effects of the Invention] As described above, the silicone rubber inclusion according to the present invention has a low sound velocity, a sound impedance approximately the same as that of the human body, and a low attenuation rate, and is suitable for acoustic lenses, phantoms,
It is also very useful as a material for water bags and the like.

Claims (1)

Scope of Claims: (a) 100 parts by weight of an organopolysiloxane containing a halogen-substituted alkyl group; (b) a density of 2.0 parts with an average particle diameter of 0.1 to 1.0 μm;
A silicone rubber composition for an acoustic medium comprising: 0 g/cm^3 or more of an inorganic metal oxide powder and/or 10 to 200 parts by weight of a metal powder; (iii) a crosslinking agent and/or a curing catalyst.