JP2733610B2 - Medical fixation material - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION << Field of Industrial Use >> The present invention relates to a medical fixing material.

More specifically, the present invention relates to a medical fixing material having no self-adhesiveness by blending an ethylene-vinyl acetate copolymer resin with a thermoplastic polycaprolactone resin having a softening point of 50 to 60 ° C.

The self-adhesiveness of the medical fixing material of the present invention is improved without impairing the properties of a conventionally used known thermoplastic polycaprolactone resin alone, so that the working time is significantly reduced.

《Prior art》 Conventionally, in the treatment of the orthopedic field such as the treatment of fractures,
When fixing the affected part, it was common to use a cast or a splint material.

As a cast, a method of dissolving gypsum in water, impregnating it with a support such as a bandage, and allowing it to stand for a certain period of time to solidify the gypsum was common.

However, the method using gypsum has the following disadvantages.

In other words, it is “bulky” and “heavily affected” for the patient to whom it has been applied. It is not easy to start over. Gypsum powder is scattered. There is a thermoplastic polycaprolactone resin composition, a trans-polyisoprene resin composition or the like impregnated in a network, woven or non-woven fabric of a certain size.

This is a hardened state during storage, and is used in a procedure of softening with hot water or hot air at the time of use, winding around an affected part, and then hardening again.

A splint material is also called a splint, and a strip-shaped soft metal or a thermoplastic resin composition having a low softening temperature has been used as it is.

Examples of disclosure using a thermoplastic resin having a low softening temperature as a casting or splint material are disclosed in
52-64192, JP 54-122354, JP 56-43957, JP 5
5-88767, JP-A-59-81042, JP-A-59-108059, JP-A-59-108059
No. 207156.

<< Problems to be Solved by the Invention >> However, when the thermoplastic polycaprolactone resin having a low softening temperature as described above is used as a medical fixing material, the following problems occur.

That is, when the above-mentioned material, particularly a cast or splint material made of the polycaprolactone resin composition is softened and applied to a patient, the softened resin surfaces are likely to adhere to each other, and the work is performed during the work. Once it adheres, it takes a long time to peel it off and start over.

In addition, when such rework is performed, the finished state is not good.

In addition, the polycaprolactone resin composition for a medical fixing material disclosed in the above-mentioned various publications is obtained by adding one kind of polycaprolactone resin as a main resin component to another resin and / or a stabilizer, an inorganic filler, and a coloring agent. Are blended. However, a medical fixing material comprising only the above resin composition is not yet sufficient.

In view of such a situation, the present inventors have made intensive studies and completed the present invention.

<< Constitution of the Invention >> That is, the present invention provides a resin composition obtained by blending (a) polycaprolactone resin at 70 to 90% by weight, (b) ethylene-vinyl acetate copolymer resin at 10 to 30% by weight, and a filler if necessary. And a medical fixative comprising a composition blended with

The point of the present invention is that by blending a certain amount of the ethylene-vinyl acetate copolymer resin with the above polycaprolactone resin, the self-adhesiveness of the resin composition at the time of softening is relaxed without impairing other properties.

In addition, blending two different grades of polycaprolactone resin has improved the bending strength, which is somewhat insufficient for a single resin of the corresponding relative viscosity.

The relative viscosity described in the present invention is a viscosity measured using a capillary viscometer (Ubbelohde viscometer). The measurement was performed according to JIS K6726. However, the value is measured at a toluene concentration of 1% as a solvent and at a temperature of 25 ° C ± 0.05 ° C.

Among the polycaprolactone resin blends described in the present invention, the polycaprolactone resin having a relative viscosity of 1.50 to 2.80 is a typical one having a molecular weight distribution as shown in the GPC chart of FIG.

In the polycaprolactone resin blend described in the present invention, the polycaprolactone resin having a relative viscosity of 1.15 to 1.50 is typically a grade having a molecular weight distribution as shown in the GPC chart of FIG. is there.

The thermoplastic polycaprolactone resin having a softening point of 50 to 80 ° C., which is one of the blended resin compositions used in the medical fixing material of the present invention, and which is solid at room temperature is as follows. Manufactured.

That is, it is obtained by ring-opening addition polymerization of a lactone monomer such as an ε-caprolactone monomer in the presence of an initiator having an active hydrogen group and a catalyst.

Organotin compounds, catalysts used for this reaction,
Organic titanium compounds and organic tin halide compounds are common, and the amount used is 0.1 to 5000 p
pm, preferably 10-100 ppm.

The reaction temperature is suitably from 100 to 230 ° C, and the reaction is preferably performed in an inert gas.

It is not preferable to set the reaction temperature to 230 ° C. or higher. Because the depolymerization temperature of polycaprolactone is about 220-230
This is because, when the reaction is performed at a higher temperature than this, the polymer is decomposed and the molecular weight does not increase.

On the other hand, if the reaction temperature is lower than 100 ° C, the reaction rate is low and the efficiency is low.

The thermoplastic polycaprolactone resin has various molecular weights (ie, relative viscosities) from liquid to solid at room temperature, and is used for various applications. Most preferred is a polycaprolactone resin having a relative viscosity of 1.50 to 2.80. Incidentally, polycaprolactone resins having a relative viscosity of 1.50 to 2.80 are commercially available for various uses, for example, a booster operation object (Japanese Patent Application Laid-Open No. 60-240692), a plastic clay (Japanese Patent Application Laid-Open No. 61-42679), It is used for medical casts (Japanese Patent Application Laid-Open No. 58-81042), medical fixing materials, face masks for radiation irradiation, and molding of wigs (Japanese Patent Application Laid-Open No. 60-215018).

Specific examples of polycaprolactone resins having relative viscosities of 1.15 to 2.80 include caprolactone H-1, -5, -7 manufactured by Daicel Chemical Industries, Ltd. and commercially available.
and so on.

Among them, polycaprolactone resins having a relative viscosity of 1.15 to 1.50 are also commercially available for various uses, and are used as general resin modifiers.

Specific examples thereof include caprolactone H-1 manufactured by Daicel Chemical Industries, Ltd. and commercially available.

Therefore, these commercially available products may be purchased and used.

The GPC chart of FIG. 1 shows the molecular weight distribution pattern of the resin composition when the above two kinds of polycaprolactone resins having different relative viscosities (that is, two kinds of different molecular weight distributions) are blended at a predetermined ratio. It becomes something like

As shown in the GPC chart shown in FIG. 1, the characteristic of the molecular weight distribution pattern of the blended resin composition is that the main peak is divided into a plurality of peaks as compared with a single case.

By being separated into a plurality of peaks, it can be confirmed that they are blended.

FIG. 4 shows the GP having a viscosity (ie, molecular weight distribution) equivalent to that of the blended resin composition.
It is a C chart.

FIG. 5 is a diagram in which three types of GPC charts of a single resin are synthesized by matching the positions of the horizontal axes.

Polycaprolactone resins having two different relative viscosities (that is, molecular weight distributions) as described above are blended at a predetermined ratio by the following method.

That is, an ethylene-vinyl acetate copolymer resin described later and resin pellets, flakes, and powders of each grade may be purchased and blended by an extruder.

After the respective capacities of the polycaprolactone resins are discharged from the polymerization vessel after the polymerization, the resins in the state of the respective high-viscosity substances may be mixed in an extruder.

These methods are appropriately selected depending on whether there is a difference between a raw resin manufacturer or a processor that purchases and processes raw materials.

In the raw material resin manufacturer, it is appropriately selected according to the relationship with the production amount.

The other resin of the blended resin composition used for the medical fixing material of the present invention, that is, the ethylene-vinyl acetate copolymer resin, is not particularly limited, as long as it is of a grade used for ordinary molded articles. Any is fine.

The ethylene-vinyl acetate copolymer resin as described above is produced by copolymerizing an ethylene monomer and a vinyl acetate monomer.

The copolymerization reaction includes a suspension method, an emulsion method and the like, and the ethylene-vinyl acetate copolymer resin used in the present invention may be any resin produced by any method.

The ethylene-vinyl acetate copolymer resin is broadly defined as having a copolymerization ratio of ethylene monomer and vinyl acetate monomer of about 60% to 90%, but the grade used in the present invention is commercially available. Standard grade, that is, 80-86% of ethylene content
The degree of softening point (Vicat method) is particularly preferably 60 to 85 ° C.

As specific examples, Evaflex 550, Evaflex 560, Evaflex P-0803, manufactured by Mitsui Polychemicals, Inc.
Sumitomo Chemical Epartate D-2011, Epartate D-3011 and Epartate D-3022.

The method for uniformly mixing the polycaprolactone and the ethylene-vinyl acetate copolymer resin is not particularly limited, and examples thereof include melt kneading using an extruder, a kneader, a Hanbury mixer, or the like.

Blend ratio of polycaprolactone resin to ethylene-vinyl acetate copolymer resin is 70-30% by weight -90-10% by weight
Is suitable.

If the blend ratio of the ethylene-vinyl acetate copolymer resin to the polycaprolactone resin is less than 10%, the effect of improving the self-adhesiveness is not sufficient.

On the other hand, if it exceeds 30% by weight, the viscosity and softening temperature at the time of softening become too high, and the curing speed becomes too fast, so that it becomes difficult to handle.

A strong correlation is observed between the blending ratio of the ethylene-vinyl acetate copolymer resin to the polycaprolactone resin, the softening temperature, and the curing speed.

That is, as the blending ratio of the ethylene-vinyl acetate copolymer resin to the polycaprolactone resin increases, the softening temperature increases and the curing speed increases. The curing speed can be controlled not only by the blend ratio of the ethylene-vinyl acetate copolymer resin to the polycaprolactone resin but also by the molecular weight of the polycaprolactone.

When the resin composition thus blended is applied to the use of the present invention, the following method may be used.

In other words, the resin molding maker manufactures the above blended resin pellets in the form of strips or 2 to 10 mm,
Preferably, it may be formed into a plate having a thickness of 3 to 5 mm.

The blended resin composition used in the present invention may be white or may be colored in blue or the like.

When the above-mentioned strip-shaped medical fixing material is actually used, prepare hot water having a temperature of about the softening point or soften the resin with a heater such as a hair dryer using electric heat, and as described above. Used for

In addition, the resin manufactured by the above method can be stored or transported for several months, but the one resin, polycaprolactone resin, is a polyester resin, which is unique to ester bonds. Is reduced in molecular weight due to hydrolysis of the compound, making it brittle.

In order to prevent this, if a part of epoxy resin is added and polymerized in place of the above-mentioned trace amount of water as an initiator, the obtained resin is remarkably improved in hydrolysis resistance.

<< Effects of the Invention >> The use of a medical fixing material comprising a thermoplastic resin composition in which a polycaprolactone resin and an ethylene-vinyl acetate copolymer resin are blended according to the present invention results in improved self-adhesiveness, resulting in reduced workability. The time is significantly shortened, the bending strength is significantly improved, the viscosity at the time of melting is reasonable, the management is easy, there is no change over time, and the patient is uncomfortable. Is not preferred.

Further, the medical fixing material comprising the blended thermoplastic resin composition used in the present invention has excellent dimensional stability.

Hereinafter, the effects of the present invention will be specifically described with reference to Examples and Comparative Examples.

Examples -1 to 6 Each composition shown in Table 1 was selected and kneaded at 150 ° C for 30 minutes using a Brabender plastograph.

Next, this resin was press-molded at a temperature of 100 ° C. so as to have a thickness of 3 mm.

The bending strength was measured 3 to 5 hours after press molding.
Table 1 shows the measured data.

The polycaprolactone resin used was commercially available polycaprolactone H7 (manufactured by Daicel Chemical Industries, Ltd .: relative viscosity 2.3).
4) Similarly, Prolactone H1 (manufactured by Daicel Chemical Industries, Ltd .: relative viscosity 1.28), ethylene-vinyl acetate copolymer resin (EV: evaflex 560 manufactured by Mitsui Polychemicals, Inc.), talc as a filler, and titanium oxide Epicoat 828 (EP) was used as an epoxy resin.

[Measurement method of bending strength] According to JIS K7203.

However, the measurement was performed under the conditions of a distance between supporting points of 4 cm, a test speed of 5 mm / min, a temperature of 20 ± 2 ° C., and a humidity of 65 ± 5% RH, and the stress when bending 5 mm was obtained.

 The sample piece is 8 cm long, 3 cm wide and 3 mm thick.

Comparative Example The same procedure was performed as in Example 1 except that the ethylene-vinyl acetate copolymer resin was not blended.

 The results are shown in Table 1.

However, the bending stress (Kg / mm2) in Table 1 is as follows.

: 3.10: 3.06: 2.91: 3.17: 3.31: 3.50: 2.97 [Evaluation of self-adhesiveness] Depending on the condition when the resin plates softened by immersion in 70 ° C hot water are pressed and peeled after 2-3 seconds 〇 × evaluation was performed.

〇: No adhesion ×: Adhesion The results in Table 1 clearly show that Examples 1 and 2 in which the ethylene-vinyl acetate copolymer resin was blended were excellent in both bending stress and self-adhesion.

[Brief description of the drawings]

FIG. 1 is a GPC chart of a composition obtained by blending two kinds of polycaprolactone resins having different relative viscosities used in the medical fixing material of the present invention. FIGS. 2 to 4 are GPC charts of polycaprolactone resins each having a single relative viscosity. FIG. 5 is a synthesis of the GPC chart of the polycaprolactone resin having the relative viscosity shown in FIGS.

Claims (4)

(57) [Claims] 1. A resin composition obtained by blending (a) 70 to 90% by weight of a polycaprolactone resin and (b) 10 to 30% by weight of an ethylene-vinyl acetate copolymer resin and, if necessary, a composition obtained by blending a filler. Medical fixing material. 2. A polycaprolactone resin having a relative viscosity of 1.50 to
Polycaprolactone resin with 2.80 and relative viscosity 1.15 ~
Polycaprolactone resin with 1.50 weight ratio 85/15 ~ 3
The medical fixing material according to claim 1, which is a resin composition blended at a ratio of 0/70. 3. The medical fixing material according to claim 1, wherein the polycaprolactone resin is polymerized using an epoxy resin as a part of the initiator. 4. The medical fixing material according to claim 3, wherein the epoxy resin is an epoxy resin.