JPH08280676A - Auxiliary sheet for ultrasonic diagnosis - Google Patents

Abstract

PURPOSE: To obtain an auxiliary sheet for ultrasonic diagnosis with high water absorbing ability and extremely small amt. of eluation into water by constituting the auxiliary sheet for ultrasonic diagnosis with a water absorbing sheet wherein a water absorbing polymer compd. constituted of a repeating unit expressed by a specified formula is a main component. CONSTITUTION: An auxiliary sheet for ultrasonic diagnosis is constituted of a water absorbing sheet wherein a water absorbing polymer compd. constituted of a repeating unit of the formula I is a main component. In the formula, A consists of the formula II and the formula III and its form of addition is the formula IV. Here, m, n and p are each an positive number of at least 1 and the wt. ratio calculated from the repeating numbers m, n and p is 44 (m+ p)/(mol.wt. of α-olefin oxide with a carbon number of at least 12) and n=94/6-90/10. In addition, X is a residue of an org. compd. with two active hydrogen groups and Y is a hydrocarbon group with a carbon number of at least 10 and R2 is a residue of a compd. of dicarboxylic acids.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an auxiliary sheet used for improving acoustic characteristics in ultrasonic diagnosis.

[0002]

2. Description of the Related Art In recent years, ultrasonic diagnosis has become widespread as a method for diagnosing the state of lesions in a living body. In ultrasonic diagnosis, when an air film exists between the ultrasonic probe and the body surface, the air film is an opaque substance to the ultrasonic wave, so that the traveling speed of the ultrasonic wave changes and the accurate Diagnosis becomes difficult.

For this reason, it is usual to apply a special gel component to the body surface of the affected area to be measured so that an air film is not generated, and an ultrasonic probe is pressed to make a diagnosis. However, even though this gel component uses a component that has no medical problem, it causes discomfort to the patient when applied, it takes time to wipe it after diagnosis, and clothes are soiled with insufficient wiping. There is a concern that allergies may occur depending on the constitution of the patient, and some solution has been desired for both the patient and medical personnel.

The present inventors have previously proposed an ultrasonic diagnostic auxiliary sheet comprising a water absorbent sheet obtained by crosslinking a resin sheet mainly containing ethylene oxide (Japanese Patent Application No. 6-175).
620). This is not sticky like a gel component and has a high water absorption capacity, so that it also has excellent ultrasonic transmission characteristics, and has an advantage that has never been seen before.

By the way, since the ultrasonic diagnostic auxiliary sheet is in direct contact with the human body, it is safer to absorb as little water as possible when absorbing water, and further study on this point revealed that it was more than the previously proposed one. We have developed an ultrasonic diagnostic auxiliary sheet with a small amount of elution.

[0006]

DISCLOSURE OF THE INVENTION The present invention provides an ultrasonic diagnostic auxiliary sheet having a high water absorption capacity and an extremely small amount of elution with respect to water, the gist of which is the following general formula (1): The ultrasonic diagnostic auxiliary sheet is composed of a water-absorbing sheet containing a water-absorbing polymer compound composed of a repeating unit represented by

[0007]

Embedded image Hereinafter, the present invention will be described in detail. The ultrasonic diagnostic auxiliary sheet of the present invention is mainly composed of a water-absorbing polymer compound composed of the repeating unit represented by the general formula (1). In the above formula (1), the addition form of the alkylene oxide chain portion represented by A includes an ethylene oxide chain represented by the repeating unit m and a repeating unit p.
The ethylene oxide chain represented by is located at both terminals with the α-olefin oxide chain represented by repeating unit n having 12 or more carbon atoms sandwiched therebetween.

Two ethylene oxide chains account for 90 to 94% by weight (hereinafter "%") in the alkylene oxide chain portion.
Abbreviated), and 6 to 10% by weight of α-olefin oxide chain having 12 or more carbon atoms is present. In short, the weight ratio calculated from these repetition numbers m, n, p is (molecular weight of ethylene oxide: 44) (m + p) / (carbon number 12
The above-mentioned molecular weight of α-olefin oxide) n = 94/6
It is set to be 90/10. When the two ethylene oxide chains are less than 90%, the hydrophobicity becomes high and the water absorption decreases, and when it exceeds 94%, the elution amount with respect to water increases.

The water-absorbing polymer compound represented by the above (1) can be obtained by using the following two components (A) and (B). (A) Ethylene oxide is addition-polymerized to an organic compound having two active hydrogen groups, and then α-containing 12 or more carbon atoms.
Weight average molecular weight of 5,000 obtained by addition-polymerizing olefin oxide and further ethylene oxide
~ 30,000 alkylene oxide compounds.

(B) Dicarboxylic acid compounds.

Examples of the organic compound having two active hydrogen groups include ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol,
Examples thereof include bisphenol A, butylamine, aniline, polytetramethylene glycol and the like.

In the above (A), the α-olefin oxide having 12 or more carbon atoms, which is used as a compound for addition polymerization with ethylene oxide, is particularly limited as long as it is an epoxide compound having an alkylene group having 12 or more carbon atoms. But more preferably an epoxide compound having an alkylene group having 12 to 30 carbon atoms.

The ethylene oxide and the α-olefin oxide having 12 or more carbon atoms, which are added to the organic compound having two active hydrogen groups in three stages, have a total ethylene oxide content of 90 to 94% and an α-olefin compound having 12 or more carbon atoms. -Set the amount of olefin oxide to 6-10% of the total.

In the above (A), ethylene oxide, α-olefin oxide having 12 or more carbon atoms, and ethylene oxide are sequentially added by block using the above components at a temperature of about 90 to 200 ° C. with caustic alkali as a catalyst. It is obtained by polymerizing and has a weight average molecular weight of 5,
It is preferably set to 000 to 30,000.

Examples of the dicarboxylic acid compound (B) include dicarboxylic acid, dicarboxylic anhydride, and lower alkyl ester of dicarboxylic acid. Examples of the dicarboxylic acid include phthalic acid, isophthalic acid, terephthalic acid,
Malonic acid, sebacic acid, fumaric acid, adipic acid, etc. are mentioned, and these dicarboxylic acid anhydrides are mentioned. Examples of the lower alkyl ester of dicarboxylic acid include methyl ester, dimethyl ester, ethyl ester, diethyl ester of the above various dicarboxylic acids,
There is propyl ester.

The water-absorbing polymer compound used in the present invention can be obtained by adding (B) to the above (A) and dehydrating or dealcoholizing under heating and reduced pressure. The water-absorbing polymer compound thus obtained preferably has a weight average molecular weight of 15,000 to 300,000.

The ultrasonic diagnostic auxiliary sheet of the present invention is produced by molding the above water-absorbing polymer compound into a sheet. As a method for producing a sheet, there are a melt extrusion method, a calendar method and the like, and in particular, a sheet can be easily formed by melt extrusion molding. Further, this sheet is insoluble in water and has water absorbability and can be used as it is. However, it can be subjected to a crosslinking treatment to improve the strength.

Crosslinking can be carried out by irradiation with ionizing radiation or ultraviolet rays. As the ionizing radiation, an electron beam, γ ray, X ray or the like can be used. Irradiation is preferably carried out in a substantially oxygen-free state such as substitution with an inert gas such as nitrogen. When the dose of ionizing radiation is smaller than 0.5 Mrad, the degree of crosslinking is small and the irradiation effect is small in terms of strength improvement.
Since the water absorption is extremely reduced when the amount exceeds Mrad, the absorbed dose is preferably in the range of 0.5 to 20 Mrad. Further, as a cross-linking method, a cross-linking agent may be blended and heat-cross-linked.

The auxiliary sheet of the present invention is a sheet similar to a normal plastic sheet when it is not allowed to absorb water, and when it absorbs water, it swells and gels. The water absorption rate can exceed 90%, and an acoustic impedance substantially the same as that of the living body can be obtained. This water-impregnated state is used by allowing it to stand still so as to be in close contact with the patient's body surface. It may also be attached to an ultrasonic probe for use.

Generally, the thickness of the auxiliary sheet of the present invention is preferably in the range of 0.1 to 2 mm in the non-water-absorbing state. Thickness is 0.1
If it is less than mm, it has no strength in a water-absorbed state, and if it exceeds 2 mm, it has a water absorption rate of more than 90%, which makes it heavy and difficult to handle.

The auxiliary sheet of the present invention has a high water absorption rate and an excellent ultrasonic wave transmission characteristic, and since it has a very low elution content with respect to water, it can be used with confidence. And it is not sticky like conventional gel components and does not stick to the body surface. Further, the auxiliary sheet of the present invention is characterized in that it can be dried and incinerated if left for one day to several days after use, that no harmful components are produced even when incinerated, and that it absorbs ionic water well. Therefore, for example, even if the water contains an antiseptic solution, it can absorb water rapidly, which has many advantages that have never been seen.

[0022]

EXAMPLES Specific examples will be described below with reference to examples. Example 1 After addition-polymerizing ethylene oxide to ethylene glycol, α-olefin oxide (having 12 carbon atoms)
And C14 epoxide compound mixture, molecular weight 19
6) addition polymerization of ethylene oxide, and further addition polymerization of ethylene oxide (weight average molecular weight 1
3,000) to which 1.9 parts of dimethyl sebacate was added,
Transesterification is performed to obtain a weight average molecular weight of 120,000.
A water-absorbent polymer compound of The water-absorbing polymer compound was composed of the repeating unit represented by the general formula (1), and X, R ₂ , m, n and p were as follows. The weight ratio calculated from the number of repetitions m, n, and p in A of the formula (1) was 44 (m + p) / 196n = 94/6.

[0023]

Embedded image This water-absorbing polymer compound was heated at a T-die temperature of 1 using an extruder.
When extruded at 20 ° C., a water-absorbent film having a thickness of 500 μm was obtained, and potassium permanganate consumption and evaporation residue were measured as elution properties with respect to water. Elution with potassium permanganate consumption 6 ppm and evaporation residue 14 ppm The quantity was at a very low level. The consumption amount of potassium permanganate was determined by immersing a sheet having an area of 150 cm ² in a beaker containing 300 cc of distilled water at 60 ° C. for 30 minutes while maintaining the temperature, and then rapidly filtering to collect a filtrate, The filtrate was measured for potassium permanganate consumption. The evaporation residue is obtained by concentrating and drying the above filtrate,
It was determined from the weight of the residue. The sheet is irradiated with γ-rays at an absorbed dose of 10 Mrad and crosslinked to obtain 20 cm × 30
It was cut into a size of cm. The elution amount after cross-linking was maintained at a low level such as potassium permanganate consumption of 9 ppm and evaporation residue of 22 ppm.

This sheet was sufficiently absorbed with ion-exchanged water (water absorption rate: 91%), excess water was cut off and placed on the abdomen, and ultrasonic diagnosis was performed using a Convex probe made by GE Yokogawa Medical System. The water-absorbed sheet swelled and gelled to a thickness of 1 mm in a flexible state and was well-adapted to the body surface and adhered well, but did not stick to the skin at all, and the body surface had no slimy feel after use. . Further, there was no breakage during diagnosis, the water retention was good, and the diagnostic image was extremely clear.

Comparative Example To an alkylene oxide compound obtained by addition-polymerizing ethylene oxide to ethylene glycol (weight average molecular weight 10,000), 2.2 parts of dimethyl terephthalate was added, and transesterification reaction was carried out to obtain a water solution having a weight average molecular weight of 130,000. A polymeric compound was obtained. And it was made to be water-absorbing by crosslinking in the same manner as in the example. This sheet had the same performance as the sheet of Example 1, but when the consumption amount of potassium permanganate and the evaporation residue were measured, the consumption amount of potassium permanganate was 20 ppm, and the evaporation residue was eluted in the 40 ppm range. The quantity was a little big.

[0026]

According to the present invention, it is possible to obtain an ultrasonic diagnostic auxiliary sheet which has a high water absorption property and, as a result, has an excellent ultrasonic wave transmission characteristic, and further has an extremely small amount of elution in water, which can be used safely. .

Claims (1)

[Claims] 1. An ultrasonic diagnostic auxiliary sheet comprising a water-absorbing sheet containing a water-absorbing polymer compound composed of a repeating unit represented by the following general formula (1) as a main component. Embedded image