JPH01175855A - Surgical monofilament seaming thread - Google Patents

Abstract

PURPOSE:To obtain a surgical monofilament seaming thread, having flexibly sufficient strength being absorbed in vivo over a long period, by spinning a polycaprolactin polymer of specific relative viscosity to be linearly melted while applying an elongation process and obtaining the monofilament seaming thread of predetermined thickness. CONSTITUTION:A surgical monofilament seaming thread is a seaming thread elongated and formed by a polycaprolactin copolymer of 2.0-3.2 relative viscosity. The obtained polycaprolactin monofilament seaming thread, while it is a monofilament, provides a small Young's modulus being excellent in linear tensile strength and knot strength. The thermo-plastic polycaprolactin polymer, used for the seaming thread, is obtained by ring opening additionally polymerizing lactin monomer of epsilon-caprolactin monomer or the like under the presence of an initiator and a catalyst having an active hydrogen radical. As the catalyst in use, an organic tin compound, organic titanium compound and an organic halide tin compound or the like are generally used, and the quantity of use is 0.1-5,000ppm for a starting material in a reaction temperature of 100-230 deg.C suitable in inert gas preferable.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a surgical suture, specifically made of a polycaprolactone polymer, which is flexible and has sufficient strength.
The present invention relates to a surgical monofilament suture that is absorbed into the body over a long period of time.

(Prior art) Surgical sutures are broadly classified into monofilaments and multifilaments such as twisted threads and braided threads based on their shape, and their materials include synthetic polymers such as nylon, polyester, and polypropylene, and stainless steel. Rust-proof metal wire or animal fibers such as silk thread are commonly used.

In addition, in recent years, high molecular weight polycaprolactone has attracted attention for medical use, and
As seen in US Pat. No. 7, polycaprolactone polymers have been used to coat sutures.

(Problems to be Solved by the Invention) In general, monofilament sutures have a smooth surface and have the advantage of good tissue passage during use. This appearance of hardness makes the thread feel stiff, and when the thread is wound into a ring for packaging, the ring-like curls remain, making it difficult to handle.

On the other hand, multifilament sutures are much more flexible than monofilament sutures, have a lower flexural modulus, and are superior in terms of strength against repeated bending, but on the other hand, they lack surface smoothness and require surface coating treatment. Is required. This coating process is useful for safely adjusting the number of knots, but if the coating agent is non-bioabsorbable, there is a risk that the coating agent peeled off from the thread surface will diffuse into the body as foreign matter, so the material of the coating agent is Careful consideration is required.

(Means for Solving the Problems) The present invention provides a medical suture described above, particularly a monofilament suture that has improved the disadvantages of monofilament suture, such as high flexural modulus (Young's modulus) and lack of flexibility. A polycaprolactone polymer having a relative viscosity of 2.0 to 8.2 is melt-spun into a linear shape and subjected to a drawing process to form a monofilament suture thread of a predetermined thickness.

Polycaprolactone polymers have favorable properties as sutures, such as being non-toxic and being gradually decomposed and absorbed within living tissues. Polycaprolactone polymers used for coating sutures in this type of field have a relative viscosity of 1.8 to 1.5, but in the present invention, the relative viscosity is 2.
．． 0 to 8.2, the Young's modulus is small, and therefore,
It is a flexible monofilament suture.

Further, the elongation at break of the polycaprolactone monofilament suture of the present invention described above can be controlled by subjecting it to annealing (heat treatment) after stretching. The elongation at break is closely related to the elastic modulus of the yarn, and in general, if the yarn is sufficiently drawn and has little elongation, the elastic modulus will be high, and if the yarn has a large elongation, the elastic modulus will increase. It gets lower.

Polycaprolactone polymer is particularly soft among the polymers that have been used as suture threads, so for example, threads with an elongation at break of 100% or more are too pliable and have no stiffness, reducing their performance as suture threads. On the other hand, if the elongation at break is less than 15%, there will be little elongation, so experience will be needed to get used to how to apply force when tying, and especially in the case of thin sutures, the suture may be accidentally torn when tying. . For this reason, the elongation of the monofilament, which is easy to handle and has high tensile strength and moderate flexural modulus, is preferably 80 to 80%.

In addition, bioabsorbable sutures such as catgut, polyglycolic acid, polyglycolic acid/PoIJL-lactic acid copolymer, and chitin are known, but these have characteristics that make them unsuitable as absorbable sutures. be. For example, Katgutsudo's thread is hard and difficult to handle, and its absorbency is adjusted with chromium, but there are variations in absorbency between products, and its biocompatibility is not very good. Polyglycolic acid has sufficient tensile strength and is stable with little variation in solubility, but because the polymer is hard, it is difficult to form it into monofilament sutures of the commonly used thickness. Furthermore, chitin fibers have good solubility, but when wet, they swell and their tensile strength decreases. However, the suture according to the present invention is soft and has a small difference in dry and wet strength, and has a slower dissolution rate than sutures made of catgut, polyglycolic acid, polyglycolic acid/poly-L-lactic acid copolymer, chitin, etc., and after surgery. Because the strength of the suture lasts for a long time, it is ideal for areas that require long-term suture retention tension, such as cardiovascular surgery, organ transplantation, and pediatric surgery during the growing period.

The polycaprolactone suture of the present invention can be easily attached with needles like conventional sutures made of polypropylene or nylon, and can be made into a polycaprolactone monofilament suture with needles at one or both ends. Gentle low temperature sterilization methods at temperatures not exceeding 60° C., such as gaseous sterilizers such as sterilizers and radiation sterilization such as A-rays, can be applied.

Furthermore, the suture thread can be colored by using a heat-stable dye that is safe for the human body, such as titanium white or phthalocyanine blue, during melt spinning.

The thermoplastic polycaprolactone polymer used in the suture of the present invention is produced as follows.

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

Catalysts used in this reaction are generally organotin metal compounds, organotitanium compounds, organohalogenated tin compounds, etc., and the amount used is 0.1 to 5,000 m
000 ppm, preferably 10-100 ppm
It is. The reaction temperature is suitably 100 to 280°C, and preferably carried out in an inert gas atmosphere.

It is not preferable for the reaction temperature to be higher than 280°C. This is because the depolymerization temperature of polycaprolactone is about 280 ~
This is because the temperature is 280°C, and if the reaction is carried out at a higher temperature, the polymer will decompose and the molecular weight will not increase. On the other hand, when the reaction temperature is below 100°C, the reaction rate is slow;
ineffective.

This thermoplastic polycaprolactone polymer has various molecular weights (i.e., relative viscosities) ranging from liquid to solid at room temperature, and is used for various purposes. The polycaprolactone polymer used has a relative viscosity of 2.0 to 8.2.

Polycaprolactone polymers having a relative viscosity of 22.0 to 8.2 are commercially available for various uses, such as boosting objects (Japanese Patent Laid-Open No. 6O-240692), plastic clay (Japanese Patent Laid-Open No. 60-240692), 6l-42679), medical cast (Japanese Patent Laid-open No. 58-81042L splint material, face mask for radiation irradiation, wig mold coverage (Japanese Patent Laid-open No. 60-810-
215018), etc.

Specific examples of polycaprolactone polymers having a relative viscosity of 2.0 to 8.2 include PCL-H4 and H7, which are manufactured by Daicel Chemical Industries, Ltd. and are commercially available.

In addition, relative viscosity is according to JI8 standard (K-6726),
Solvent: Toluene, concentration = 1%, temperature = 25 ± 0.05°C
Measure with.

(Function) The polycaprolactone monofilament suture obtained by melt-spinning and drawing a polycaprolactone polymer with a relative viscosity of 2.0 to 8.2 has a small Young's modulus even though it is a monofilament, and has a linear tensile strength. Excellent paper strength and knot strength. Therefore, it exhibits favorable performance as a medical suture thread, fastens the suture site for a long period of time, and is coolly absorbed into the body during that time, so that it can be used to suture areas that take time to heal the living tissue. Maintains retention effect.

(Example) Example 1 A resin with a relative viscosity of 2.84 (polycaprolactone polymer manufactured by Daicel Chemical Industries, Ltd.: PC!L-H?) was melt-spun at a nozzle temperature of 220°C, and immediately after spinning, the resin was spun at 26°C. After cooling with cooling water for 6 seconds, it was wound up at a speed of 6 m/min. Then, in the first stage, the
．． The polycaprolactone monofilament suture thread was stretched 0 times, and then stretched 1.6 times in warm water at 52° C. in the second stage to obtain a polycaprolactone monofilament suture having a thickness of 0.246 ff.

Example 2 The polycaprolactone monofilament suture obtained in Example 1 above was treated with dry heat at 58°C for about 20 minutes under no tension for annealing, resulting in an annealed polycaprolactone monofilament 0-ply yarn. I did it.

Comparative Example 1 A resin with a relative viscosity of 1.58 (polycaprolactone polymer: PCT, -H4 manufactured by Daicel Chemical Industries, Ltd.) was melt-spun at a nozzle temperature of 100°C, and immediately after spinning, it was spun with cooling water at 25°C for 5 seconds. After cooling, it was wound up at a speed of 4 m/min. After that, it was stretched 7.8 times in air at 25°C,
A polycaprolactone monofilament suture having a thickness of 0.246 fl was made.

In addition, commercially available polypropylene monofilament suture thread (thickness 0.281 ff) and nylon monofilament suture thread (thickness 0.286J111) were used as Comparative Example 2 and Comparative Example 8, respectively.

The linear tensile strength, elongation at break, knot strength, and Young's modulus of Examples 1 and 2 and Comparative Examples 1 to 3 were measured. The results are shown in Table @1.

(Margins below) Table 1 (Note) Linear tensile strength is measured using Tensilon (Toyo Baldwin RTM manufactured by Toyo Baldwin Co., Ltd.) with approximately 203 sample yarns between 101 chucks.
-100) and stretch at a speed of 100 frames per minute.
The load at the time of cutting was taken as that value. The elongation at break is
The value was taken as the elongation at the break of the above linear tensile strength.

For the knot strength, a knot was made once at approximately the center of a sample thread of approximately 20011, set between the chucks of the Tensilon, stretched at a speed of 100 M/min, and the load at the time of cutting was taken as a numerical value. Young's modulus was determined by a formula from the slope of the rise of the chart that measured the linear tensile strength. Further, the wet strength of Example 2 in Table 1 was measured after being immersed in physiological saline at 87° C. for 1 hour.

Example 8 The polycaprolactone polymer used in Example 1 was
Using the same method as above, use a 4-0 equivalent suture (diameter 0.195f
f) and implanted into the dorsal muscle of a rabbit, and removed after 2 months, 4 months, 6 months, 8 months, 10 months, and 12 months.
The linear tensile strength, residual tensile strength and elongation of the sample threads before implantation were measured for each sample thread. The results are shown in Table 2.

Example 4 The suture of Example 8 was immersed in 87°C physiological saline and
The linear tensile strength, residual tensile strength, and elongation of each sample yarn taken out after 1 month, 4 months, 6 months, 8 months, 10 months, and 12 months were measured. The results are shown in Table 2.

(Effects of the Invention) As described above in detail in the Examples, the polycaprolactone monofilament suture according to the present invention is extremely flexible despite being a monofilament, and therefore easy to handle, and has a slow dissolution rate in vivo and a long length. Because it has suture retention tension for a long period of time, it is suitable for suturing areas where tissue healing takes longer than usual, and it is characterized by remarkable effects as a surgical suture thread for this type of area.Patent applicant: Nippon Shoji Co., Ltd.

Claims (2)

[Claims] (1) A drawn surgical monofilament suture consisting of a polycaprolactone polymer with a relative viscosity of 2.0 to 8.2. (2) The surgical monofilament suture according to claim 1, wherein a needle is attached to one or both ends of the suture.