JPS61283661A - Cured resin composition and acoustic transducer - 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 Field of the Invention The present invention relates to matrix compositions. More specifically, the present invention relates to a matrix composition used in a sonar transducer.

[Conventional technology and its problems]

Conventional sonar transducers consist of a number of piezoelectric ceramic pegs embedded in epoxy resin, arranged parallel to an axis, and having ceramic end faces exposed at least on the top and bottom surfaces of the matrix. An electrode is connected to the exposed surface.

The purpose of the resin matrix is not only to hold the ceramic pegs in the desired position, but also to protect them from damage.

It is known that mechanical stresses applied to widely used resin matrix materials tend to be transferred to embedded ceramic pegs to a greater extent than is desirable. Furthermore, commonly used matrix materials tend to be more acoustically reflective and have higher thermal expansion than is desirable.

[Problem that the invention seeks to solve]

It is an object of the present invention to provide a composition which overcomes or at least ameliorates some of the above-mentioned disadvantages of the matrix compositions used hitherto. Preferred embodiments of the present invention provide matrix materials that provide improved performance to sonar transducers.

As a first feature, the present invention provides hollow microspheres surrounded by resin.
crosphere) and has an acoustic impedance of 1. IX 10B~1.9X106
kty/go/s, or preferably 1.2X 106~
1.8 x 106 kg1d/s.
).

In a second aspect, the invention resides in an acoustic transducer consisting of a ceramic element embedded in a matrix according to the first aspect.

As a third feature, the invention resides in a cured resin based matrix composition that has an inverse Poisson's ratio that is substantially lower than the epoxy resin material and exhibits an acoustic impedance similar to water.

[Means for solving problems]

The present invention contains 15 to 45% by volume of hollow microspheres surrounded by resin, and has an acoustic impedance of 1.1 x 106 to 1.
．． The present invention relates to an acoustic transducer comprising a ceramic element embedded in a matrix and a cured resin composition comprising a densifying agent in an amount sufficient to provide a densifying agent within the range of 9.times.10@6 kg/go/s.

〔Example〕

Next, various embodiments of the present invention will be described, but the present invention is not limited to these embodiments.

The matrix composition of the present invention can be used, for example, with an epoxy base such as Araldite CY221, available from Ciba Geigy, and HY837, also available from Ciba Geigy, used therewith. It consists of resin materials such as curing agents.

Various plasticizers and plasticizers, such as plasticizer DYO40 manufactured by Ciba Geigy, may be added as appropriate. Compositions such as those described above are well known per se in resin manufacturing technology.

Prior art matrix resin compositions typically include 063
and an inverse Poisson's ratio of about 0.7. Poisson's ratio is the ratio of transverse strain to longitudinal strain when a rod-shaped material is stretched by applying force to both ends of the material parallel to the axis of the rod.

The inverse Poisson's ratio is the ratio of transverse strain to longitudinal strain when a rod-shaped material is compressed by applying force to both ends of the material parallel to the axis of the rod.

Prior art matrix resin compositions also typically have an acoustic impedance (density x speed of sound) of 2.2 x 106 kg/go/S.

In the present invention, hollow microspheres are added to the epoxy matrix resin prior to curing. Preferred microspheres include those sold under the registered trademark Expancel (same as the registered trademark rEXPANcEL DE J). These microspheres have walls of a copolymer of vinylidene chloride and acrylonitrile and have an average particle size of 401! m, and the bulk density is 20 kg/cm3.

Another example of a preferred microsphere is the one sold by Union Carbide under the trade name tlcAR, which has an average particle size of 43ρ and a bulk density of 100 to 150 kg/m.
3, which has a phenolic resin wall.

In the composition according to the invention, the amount of microspheres in the cured resin is between 15 and 45% of the matrix composition.
% by volume, preferably 25-35% by volume, more preferably about 30% by volume. Microsphere content is 45% by volume
If it exceeds 45%, the uncured resin becomes increasingly difficult to remove gas,
Furthermore, if the amount is less than 15% by volume, the inverse Poisson's ratio will be significantly reduced.

In addition to microspheres, the matrix compositions of the present invention include densifying fillers, such as lead oxide. The amount of the densifying filler added is such that the acoustic impedance of the product is close to the acoustic impedance of water, i.e. between 1.4×106 kg/nl'/s and 1.8×106 kg/m2/s. It is preferably selected to be approximately 5X 106 kg/d/S.

A typical composition according to the invention consists of 60% by volume of cured resin, 30% by volume of microspheres, and 10% by volume of filler. The composition according to the invention is obtained by combining the following ingredients and then cured.

Epoxy resin Araldite CY 221 or ECC0GEL 1365.1i0
35-60% by weight Curing agent HY 837 10-18% by weight
Plasticizer DY 040 5-10% by weight Plastic Micro Balloons 0.8
~2% by weight other fillers such as lead oxide or ZrO2 12-48% by weight The resulting product is as follows.

49-77% by volume Cured resin 21-46% by volume Microspheres 1-10% by volume Filler A preferred composition according to the present invention is 60% by volume of cured resin.
, 30% by volume of microspheres and 10% by volume of filler, made by combining the following ingredients and then cured.

Epoxy resin Araldite CY221 46.1% by weight Curing agent HY 837 13.8% by weight
Plasticizer DY 040 8.9% by weight E
xpancel DB 1.1
Weight% Lead oxide 32.1% by weight
Conventional microspheres are added to curable resin compositions to reduce the density and increase stiffness of the resin composition. The physical properties of these microspheres are contrary to the physical properties desired for the matrix of a sonar transducer. Similarly, the use of dense fillers in the absence of microspheres is disadvantageous in matrices used in sonar.

The matrix compositions of the present invention have been found to have Poisson's ratios similar to epoxy resins traditionally used in sonar transducers, but surprisingly less than 0.8, e.g. 3-0.
It was found to have an inverse Poisson's ratio of between 5 and 273, ie less than 273 of conventionally used epoxy resins.

To measure the inverse Poisson's ratio, an extensometer (tensom
ether) was used with a special jig to apply compressive force to the epoxy resin sample.

The method consists of placing a cylindrical rod of epoxy resin with both ends cut at right angles to the axis of the rod between the clamping mechanisms of the extensometer. A force was applied to the rod and the change in length and diameter of the rod was measured. When the length of the first rod is L1 and the diameter is D,
The inverse Poisson's ratio was calculated by the ratio expressed by the formula (where ΔD is the increase in diameter and ΔL is the decrease in length).

This measurement was repeated many times to establish reproducibility.

Table 1 compares the Poisson's ratio and inverse Poisson's ratio of a matrix according to the invention having the composition described above and an epoxy matrix.

TABLE 1 Those skilled in the art will readily be able to select other suitable polymers and resins for use in the matrices of the present invention. Preferably, it does not produce f'oam, has a suitable pot life, a curing temperature low enough so as not to damage the embedded ceramic composition, and suitable mechanical, electrical, thermal and chemical properties. Resins should be selected that have specific properties. curing agent or catalyst
Plasticizers and/or other additives may be selected in the same way as in 1, the proportions being adjusted by routine tests.

Microspheres that deform under static pressure but recover their original shape under load are particularly preferred; microspheres made of glass satisfy this condition very little or not at all. I understand. Although fillers other than lead oxide may be used as densifying agents, it is preferred that such fillers have a density greater than 5.

Claims (1)

[Claims] 1. 15 to 45% by volume of hollow microspheres surrounded by resin.
Contains an acoustic impedance of 1.1×10^6 to 1.
A cured resin composition comprising a densifying agent in an amount sufficient to achieve a density of 9×10^6 kg/m^2/s. 2. The composition according to claim 1, wherein the densifying agent has a density greater than 5. 3. The composition according to claim 2, wherein the densifying agent is lead oxide. 4. The composition according to claim 2, wherein the densifying agent is zirconium oxide. 5. The composition according to claim 1, which contains 25 to 35% by volume of hollow microspheres. 6. The hollow microspheres have a bulk density of 20 to 150 kg/m^.
Claims 1 and 2, which have the following:
The composition according to item 3, 4 or 5. 7. The composition according to claim 1, 2, 3, 4, 5 or 6, having an inverse Poisson's ratio of less than 0.6. 8. Claims 1, 2, 3, 4, and 5 in which the Poisson's ratio is 0.3 to 0.4 and the inverse Poisson's ratio is 0.3 to 0.5. , the composition according to item 6 or 7. 9 Claims 1, 2, 3, 4,
An acoustic transducer comprising a ceramic element embedded in a matrix according to claim 5, 6, 7 or 8. 10. The ceramic element according to claim 9, wherein the ceramic element is a piezoelectric ceramic peg arranged parallel to the axis and has exposed ceramic end faces for connection with the electrodes at least on the top and bottom surfaces of the matrix. transducer.