JP2000078694A - Composition for ultrasonic attenuation material, ultrasonic attenuation material, and method for producing ultrasonic attenuation material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a composition for an ultrasonic attenuating material, which is excellent in ultrasonic attenuating force, hardly deformed by thermal and mechanical external forces, and is therefore suitable for use as an ultrasonic probe. And an ultrasonic attenuating material, and a method for manufacturing the same. SOLUTION: A resin composition for an ultrasonic attenuating material comprising a thermoplastic resin, an inorganic filler having a density of 2 g / cm ³ or more, an α, β unsaturated carboxylic acid monomer and a polymerization initiator. The material is supplied to an extruder, heated and kneaded, and then shaped into a desired shape.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a composition for an ultrasonic attenuator, an ultrasonic attenuator, and a method for producing an ultrasonic attenuator.

[0002]

2. Description of the Related Art Conventionally, as an ultrasonic probe, as shown in FIG. 1, an acoustic lens 2 is provided on the output side of a high-frequency vibrator 1 via an ultrasonic matching layer 3 and a case 5 is provided. Is used. On the back side of the vibrator 1, a back plate 4 as a vibrator holder is fixedly mounted.

The back plate 4 is required to attenuate ultrasonic waves propagating almost completely as a function of the back plate 4 to prevent the generation of a false echo (Japanese Patent Laid-Open No. 60-201026).
No., Japanese Patent Application Laid-Open Publication No., prior art and its problems). for that reason,
As the back plate 4, a plastic or rubber material filled with an inorganic filler is used as an ultrasonic attenuation material.

[0004]

However, the ultrasonic attenuating material does not have sufficient damping force due to the limited amount of filling with the inorganic filler, and is deformed by thermal or mechanical external force. There was a drawback that it was easy to do.

The present invention solves the above-mentioned problems, and has an excellent ultrasonic damping force and is hardly deformed by a thermal or mechanical external force, and is therefore suitable for use as an ultrasonic probe. It is an object to provide a composition for use, an ultrasonic attenuation material, and a method for producing an ultrasonic attenuation material.

[0006]

The resin composition for an ultrasonic attenuating material according to the invention (hereinafter referred to as "the present invention 1") according to the present invention comprises a thermoplastic resin and a resin having a density of 2 g / cm ³ or more. It comprises an inorganic filler, an α, β unsaturated carboxylic acid monomer and a polymerization initiator.

[0007] The thermoplastic resin used in the present invention 1 is not particularly limited as long as it is a resin having an affinity for α, β unsaturated carboxylic acid-based monomers.
Polypropylene, polyamide, polyacetal, polyethylene terephthalate, polybutylene terephthalate,
Polytetrafluoroethylene, polyphenylene sulfide, polystyrene, acrylonitrile butadiene
Styrene copolymers, (meth) acrylic resins, ethylene-vinyl acetate copolymers and the like can be mentioned.

[0008] Among them, polypropylene, polystyrene, and the like having a high affinity for α, β unsaturated carboxylic acid monomers.
(Meth) acrylic resins, ethylene vinyl acetate copolymers and the like are preferred.

If the density of the inorganic filler used in the present invention 1 is too low, the attenuation performance of the ultrasonic attenuator produced using the composition is reduced, so that the content is limited to 2 g / cm ³ or more. Preferably it is 3-10 g / cm < ³ >, More preferably, it is 5-9 g / cm < ³ >.

Examples of the inorganic filler include metal powder such as iron powder, aluminum hydroxide, ettringite, silica sand, borax, alumina, talc, kaolin, calcium carbonate, silica, magnesium hydroxide, mica, fly ash, Calcium silicate, mica, molybdenum dioxide,
Talc, glass fiber, glass beads, titanium oxide, asbestos, magnesium oxide, barium sulfate, clay, dolomite, calcium silicate, calcium aluminate hydrate, etc. Is preferred because The inorganic filler may be used alone or in combination of two or more. Further, the above-mentioned inorganic filler may be subjected to a surface treatment with a silane coupling agent, a titanium coupling agent, or the like, if necessary.

The average particle size of the inorganic filler is 1 to 100 μm.
It is preferably in the range of m. If it is smaller than 1 μm,
In some cases, the material viscosity in the extruder increases, and uniform kneading cannot be performed. If it exceeds 100 μm, the surface properties of the molded product may decrease.

The α, β unsaturated carboxylic acid-based monomer used in the present invention 1 functions to plasticize the above-mentioned thermoplastic resin and increase the filling ratio of the inorganic filler, and to polymerize by heating, so that it can be used for extrusion molding. It acts to maintain the shaped shape.

As the α, β carboxylic acid monomer, a commercially available α, β unsaturated carboxylic acid or α, β unsaturated carboxylic acid ester monomer can be used.

Specific examples of the α, β unsaturated carboxylic acid include (meth) acrylic acid and itaconic acid, and examples of the α, β unsaturated carboxylic acid ester monomer include ethyl (meth) acrylate, (Meth) acrylic acid n
-Butyl, isobutyl (meth) acrylate, t-butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, lauryl (meth) acrylate, alkyl (meth) acrylate, tridecyl (meth) acrylate, Stearyl (meth) acrylate, cyclohexyl (meth) acrylate, benzyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, 2- (meth) acrylate
Hydroxypropyl, dimethylaminoethyl (meth) acrylate, dimethylaminoethyl methyl chloride (meth) acrylate, diethylaminoethyl (meth) acrylate, glycidyl (meth) acrylate, tetrohydrofurfuryl (meth) acrylate, ( Allyl (meth) acrylate, ethylene glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate, tetraethylene glycol di (meth) acrylate, di (meth) acrylate
1,3-butylene glycol acrylate, 1,6-hexanediol dimethacrylate, trimethylolpropane trimethacrylate, 2-ethoxyethyl methacrylate,
Β-hydroxyethyl acrylate, hydroxypropyl acrylate, acrylamide, 2-acrylate
Examples thereof include (5-ethyl-2-propylpyridyl) ethyl, 2-cyanoethyl acrylate, N-methylolacrylamide, and the like.

The above α, β unsaturated carboxylic acid monomers may be used alone or in combination of two or more.

The α, β unsaturated carboxylic acid monomer is used in an amount of 5 to 4 parts by weight based on 100 parts by weight of the thermoplastic resin.
A range of 0 parts by weight is preferred. If the amount is less than 5 parts by weight, the acrylic resin powder cannot be sufficiently plasticized, the inorganic filler cannot be filled at a high level, and the extrudability decreases. If the amount is more than 40 parts by weight, the material viscosity decreases. Too much, bubbles and the like are intermingled, and the surface properties and physical properties of the molded article are reduced.

The polymerization initiator used in the present invention 1 is used for polymerizing the above-mentioned α, β unsaturated carboxylic acid monomer by heating, and can induce the polymerization of the unsaturated carboxylic acid monomer. If it is not particularly limited, for example, ketone peroxide-based, peroxyketal-based, dialkyl peroxide-based, diacyl peroxide-based, peroxydiponate-based, peroxyester-based organic peroxide-based polymerization initiation, etc. Agents can be used.

More specifically, the organic peroxide-based polymerization initiator includes, for example, cumene hydroperoxide, methyl acetoacetate peroxide, 1,1-
Bis (t-hexylperoxy) 3,3,5-trimethylcyclohexane, 1,1-bis (t-hexylperoxy) cyclohexane, 1,1-bis (t-butylperoxy) 3,3,5-trimethyl Cyclohexane, 1,
1-bis (t-butylperoxy) cyclohexane,
1,1-bis (t-butylperoxy) cyclododecane, 2,2-bis (t-butylperoxy) butane, n
-Butyl-4,4-bis (t-butylperoxy) valerate, 2,2-bis (4,4-di-t-butylperoxycyclohexyl) propane, di-t-butyl peroxide, lauroyl peroxide, Stearoyl peroxide, 2,4-dichlorobenzoyl peroxide, octanoyl peroxide, benzoyl peroxide, 1,1,3,3-tetramethylbutylperoxy-2-ethylhexanoate, 2,5-dimethyl-
2,5-bis (2-ethylhexanoylperoxy) hexane, 1-cyclohexyl-1-methylethylperoxy-2-ethylhexanoate, t-hexylperoxy-2-ethylhexanoate, t-butyl Peroxy-2-ethylhexanoate, t-butylperoxyisobutyrate, t-hexylperoxyisopropyl monocarbonate, t-butylperoxymaleic acid,
t-butylperoxy-3,5,5-trimethylhexanoate, t-butylperoxylaurate, 2,5-
Dithimer-2,5-bis (m-toluoyl peroxy)
Hexane, t-butylperoxyisopropyl monocarbonate, t-butylperoxy-2-ethylhexyl monocarbonate, t-hexylperoxybenzoate, 2,5-dimethyl-2,5-bis (benzoylperoxy) hexane, t- Butyl peroxyacetate, t
-Butyl peroxy-m-toluoyl benzoate, t
-Butylperoxybenzoate, 2,4,4-trimethylpentyl-2-hydroperoxide and the like.

The above polymerization initiator is preferably used at a temperature of 60 ° C. or more, because if the 10-hour half-life temperature is too low, the α, β-unsaturated carboxylic acid-based monomer is too rapidly cured during molding and the moldability deteriorates. Are preferred.

In the present invention 1, further, if necessary,
Glass fiber, reinforcing material such as carbon fiber, filler such as wood flour,
You may add a plasticizer, a lubricant, a foaming agent, etc.

The ultrasonic attenuating material of the invention according to claim 2 (hereinafter referred to as “the present invention 2”) is an ultrasonic attenuating material obtained by curing the above α, β unsaturated carboxylic acid monomer. The inorganic filler occupies 50 to 90% by volume of the total damping material.

If the amount of the inorganic filler is too small, a sufficient damping effect cannot be obtained, and if it is too large, kneading and molding become difficult. Therefore, it is preferable that the inorganic filler occupy 50 to 90% by volume of the total damping material. .

According to a third aspect of the present invention, there is provided a method for producing an ultrasonic attenuating material, the method comprising supplying the resin composition according to the first aspect of the invention to an extruder, heating and kneading the resin composition. ,
It is to shape into a desired shape.

[0024] In the present invention 3, the polymerization initiator of 10
When the time half-life temperature is T (° C.), T ₀ −70 (° C.) <T <T ₀ −10 with respect to the extrusion temperature T ₀ of the extruder.
(° C.), whereby the curing speed is set to an appropriate speed, and a decrease in extrudability can be prevented.

The combination and the mixing ratio of the polymerization initiator and the α, β unsaturated carboxylic acid monomer differ depending on the type of the polymerization initiator, but are determined by using a gel time tester (No. 153 formula YASUUD) under the same temperature as the extrusion temperature.
Preferably, the gelation time is adjusted to be 30 to 600 seconds in the measurement by ASEIKI SEISAKUSHO. By setting the content in this range, good extrusion moldability and improvement in the surface properties of the molded product can be achieved.

In the production method according to the third aspect of the invention, the resin composition obtained by mixing the above-mentioned components is lightly stirred so as to be uniform and then charged into an extruder. The resin composition may be put into the extruder by mixing the materials lightly in advance and putting it in a powder form. The powdery substance excluding the α, β unsaturated carboxylic acid monomer is put in from the hopper, and the α, β A method of directly dropping a β-unsaturated carboxylic acid-based monomer onto a kneading shaft of an extruder by a pump may be adopted. As the extruder, either a single-screw extruder or a twin-screw extruder can be used, but a twin-screw extruder is preferably used in order to improve kneading properties.

In the production method according to the third aspect of the invention, the resin composition obtained by mixing the above-mentioned components may be formed into a shape to be produced by an extruder, or into a plate or a tube, and then produced. It may be cut into a desired shape. Further, it may be formed into a pellet by an extruder and manufactured by a conventionally known molding method such as injection molding, press molding, transfer molding and the like.

(Function) The resin composition for an ultrasonic attenuating material of the present invention 1 comprises a thermoplastic resin, an inorganic filler having a density of 2 g / cm ³ or more, α, β
Since it is composed of an unsaturated carboxylic acid-based monomer and a polymerization initiator, the thermoplastic resin is easily plasticized by kneading while heating the resin composition, which facilitates the compounding of the inorganic filler and increases the filling. It becomes easier to do.

The ultrasonic attenuating material according to the second aspect of the present invention is an ultrasonic attenuating material obtained by curing the α, β unsaturated carboxylic acid monomer, wherein the inorganic filler is contained in a volume of the total attenuating material. Because it occupies 50 to 90% by volume,
Even if the inorganic filler is highly filled, it can be easily molded and a sufficient damping effect can be obtained.

In the method for producing an ultrasonic attenuating material of the third invention, the resin composition of the first invention is supplied to an extruder, heated and kneaded, and then shaped into a desired shape. After the monomer contributes to the plasticization of the thermoplastic resin, it gradually cures, and when discharged from the extruder, the polymerization filler is highly filled with the inorganic filler without affecting the performance and physical properties of the molded article. .

[0031]

The present invention will be described in more detail with reference to the following examples.

(Examples 1 to 4, Comparative Example 1) A predetermined amount of polypropylene (trade name "Novatech PP", manufactured by Nippon Polychem Co., Ltd.), polystyrene (trade name "Stylon 433", manufactured by Asahi Kasei Corporation, methacryl) shown in Table 1 A composition for an ultrasonic attenuating material comprising cyclohexyl acid, cumene hydroperoxide (10-hour half-life temperature: 159 ° C.) as a polymerization initiator, and iron powder (density: 7.9 g / cm ² ) as an inorganic filler is biaxially mixed. Into a one-way extruder and a residence time of 5
Minutes and melt-kneaded at 180 ° C. and pelletized. The obtained pellets were supplied to a 100 × 100 × 10 mm mold, heated and pressed at 180 ° C., and the mold was cooled to obtain an ultrasonic attenuation material.

(Comparative Examples 2 and 3) Instead of the thermoplastic resin,
Unsaturated polyester (manufactured by Takeda Pharmaceutical Co., Ltd., trade name "Polymer", thermosetting resin), t-butylperoxybenzoate, t-butylperoxybenzoate (10-hour half-life temperature 105 ° C) as a polymerization initiator, inorganic substance As a filler, a predetermined amount of iron powder (density: 7.9 g / cm ² ) was stirred and supplied to a 100 × 100 × 10 mm mold.
It was heated and pressed at 0 ° C., and the mold was cooled to obtain an ultrasonic attenuator.

(Evaluation of molded article) Examples 1 to 5, Comparative Example 1,
The ultrasonic attenuating material obtained in 2 was subjected to the following evaluation. 1) Moldability The obtained molded article was marked with "O" if it could retain its shape, and "x" if it could not. 2) Ultrasonic attenuation The jelly (trade name “Sony coat” manufactured by Nichiai Acetylene Co., Ltd.) is applied to both sides of the obtained ultrasonic attenuating material, and an ultrasonic transmitter is adhered to one side, and a 1 MHz frequency is applied. Ultrasonic waves were transmitted, the ultrasonic receiver was brought into close contact with the other surface, and the amount of attenuation was measured. The above results are summarized in Table 1.

Comparison between Example 1 and Examples 3 and 4 shows that if the amount of iron powder is too small, the amount of ultrasonic attenuation decreases, and if it is too large, the moldability decreases.

[0036]

[Table 1]

[0037]

According to the composition for an ultrasonic attenuating material of the first aspect of the present invention, the composite of the inorganic filler is assisted, and the high filling can be easily performed.

According to the ultrasonic attenuating material of the present invention 2, even if the inorganic filler is highly filled, it can be easily formed and a sufficient attenuation effect can be obtained.

According to the method for producing an ultrasonic attenuating material of the third aspect of the present invention, the inorganic filler is highly filled without affecting the performance and physical properties of the molded article.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating an example of an ultrasonic probe.

[Explanation of symbols]

 1 vibrator 4 back plate

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI theme coat ゛ (reference) G01N 29/24 G01N 29/24 // B29C 47/00 B29C 47/00 F-term (reference) 2G047 EA07 GB23 4F207 AA04 AA10 AA11 AA13 AA20L AA21 AA25 AA29 AB04 AB11 AB16 AC01 AE06 AE07 AH39 KA01 KK13 4J002 AA011 AC071 AC081 BB031 BB061 BB121 BC041 BD151 BE061 BF031 BG001 CF051 GG01 001 GG01 001 001

Claims (3)

[Claims] 1. A resin for an ultrasonic attenuating material comprising a thermoplastic resin, an inorganic filler having a density of 2 g / cm ³ or more, an α, β unsaturated carboxylic acid monomer and a polymerization initiator. Composition. 2. An ultrasonic attenuator obtained by heating the resin composition according to claim 1 to cure the α, β unsaturated carboxylic acid monomer, wherein the inorganic filler is totally attenuated. An ultrasonic attenuating material characterized by comprising 50 to 90% by volume of the material. 3. A method for producing an ultrasonic attenuation material, comprising supplying the resin composition according to claim 1 to an extruder, heating and kneading the mixture, and then shaping the resin composition into a desired shape.