JP5038610B2 - Suture and manufacturing method thereof - Google Patents

Description

  The present invention relates to a suture having improved handling and tensile strength and flexibility, which are fine fibers made of a biocompatible thermoplastic resin, and a method for producing the suture.

  As the suture thread, a suture thread that has good operability at the time of operation, is easy to be sutured and ligated, and is difficult to unknot a knot is known. Conventionally used surgical sutures include a thread made of silk, a thread made of a bioabsorbable polymer, and a thread made of a synthetic fiber.

  Silk yarn is advantageous because it is flexible and has excellent knot-holding power, so it is easy to bind and has good handleability. However, silk yarn has problems such as high silk cost and low tensile strength. In particular, when wet, which is a state of use in surgery, an essential problem is that the strength when surgically tied is low.

  A polyester suture having a toughness of about 7 to about 8.5 grams / denier, an elongation to break of 30 percent or less, and a boiling water shrinkage of about 0.5 to about 3.0 percent Although there is a description of a assembled polyester suture formed from a filament (Patent Document 2), there is a demand for a suture that is further excellent in flexibility and has appropriate tensile strength and knot strength.

JP 2000-135282 A JP-A-9-164190

  An object of the present invention is to provide a suture thread with improved tensile strength and flexibility and good handleability, and a method for producing the suture thread.

That is, the present invention is composed of a biocompatible thermoplastic resin, a sea component is removed from a sea-island type composite fiber, and is composed of a fine fiber bundle having an average fiber diameter of 10 to 1000 nm, a tensile strength of 1.5 cN / dtex or more, A suture having a knot strength of 1.5 to 6.0 cN / dtex and a twist number of 50 to 1000 T / M.

  According to the present invention, it is possible to provide a suture thread that is excellent in flexibility, has appropriate tensile strength and knot strength, and is easy to handle and applicable to a living body.

Hereinafter, embodiments of the present invention will be described in detail.
The suture in the present invention includes any of short fibers, multifilaments, and spun yarns, but multifilaments are preferred from the viewpoint of handleability.

  The suture of the present invention is characterized by comprising fibers having an average fiber diameter of 10 to 1000 nm. If the average fiber diameter is less than 10 nm, the influence of intermolecular force becomes strong, or the fiber structure itself is unstable and the fineness of individual fine fibers is poor. At present, the fine fibers are uniformly dispersed. It is difficult to obtain a fiber structure. On the other hand, if the average fiber diameter exceeds 1000 nm, it is not possible to obtain a suture that is flexible and excellent in handleability as intended by the present invention. A particularly preferable range is 50 to 900 nm.

  The suture of the present invention has a tensile strength of 1.5 cN / dtex or more. When the tensile strength is less than 1.5 cN / dtex, the strength as a suture is insufficient, which is not preferable. The tensile strength is preferably 2.0 to 7.0 cN / dtex, more preferably 2.0 to 6.0 cN / dtex.

  The suture of the present invention has a knot strength of 1.5 to 6.0 cN / dtex. When the knot strength is outside the range of 1.5 to 6.0 cN / dtex, a flexible suture excellent in handleability as aimed by the present invention cannot be obtained. The knot strength is preferably 2.0 to 5.0 cN / dtex.

Further, the suture of the present invention preferably has a fiber diameter variation coefficient (CV) defined by the following formula satisfying 0 to 0.3.
Fiber diameter variation coefficient (CV) = σ / X
However, the fiber diameter here means an average value of the maximum diameter and the minimum diameter of the fiber cross section, σ indicates a standard deviation of the fiber diameter distribution, and X indicates an average fiber diameter.

  When CV exceeds 0.3, the quality of the suture may vary greatly. The fiber diameter variation coefficient (CV) is preferably in the range of 0 to 0.20 as the fiber variation coefficient capable of nano-level structure control.

The number of twists of fine fibers is Ru 50~1000T / M der. More preferably, it is 100-800 T / M. If the number of twists is less than 50 T / M, the fine fibers are scattered and the handleability may be poor. On the other hand, when the twist number exceeds 1000 T / M, the handleability may be poor because the softness peculiar to fine fibers becomes poor.

  The suture of the present invention is also preferable as a bundle of threads that satisfy the tensile strength and knot strength required by combining a plurality of multifilaments. It is also preferable to knit a bundle of yarns into a braid.

  Examples of the biocompatible thermoplastic resin constituting the suture of the present invention include polyesters such as aromatic polyester, polyamides such as nylon, polystyrene, polyvinyl alcohol, poly (ethylene-co-vinyl acetate), poly (hydroxy Polyolefins such as ethyl methacrylate) and copolymers thereof, condensation polymers such as poly (carbonate) and poly (urethane) and copolymers thereof, polylactic acid, polylactic acid-polyglycolic acid copolymer, polyhydroxy Examples include biodegradable aliphatic polyesters such as butyric acid, polycaprolactone, polyethylene adipate, and polybutylene adipate, and aliphatic polycarbonates such as polybutylene carbonate and polyethylene carbonate.

Of these, polyesters, polyamides, and polyolefins are preferable, and aromatic polyesters are particularly preferable. Aromatic polyesters include polyethylene terephthalate, polytrimethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, and aromatic dicarboxylic acids such as isophthalic acid and 5-sulfoisophthalic acid metal salt, and adipic acid, which have these main repeating units, Examples thereof include copolymers with aliphatic dicarboxylic acids such as sebacic acid and hydroxycarboxylic acid condensates such as ε-caprolactone, glycol components such as diethylene glycol, trimethylene glycol, tetramethylene glycol, and hexamethylene glycol. In particular, aromatic polyesters such as polyethylene terephthalate, polytrimethylene terephthalate, polybutylene terephthalate, and polyethylene terephthalate isophthalate and polyethylene naphthalate having an isophthalic acid copolymerization ratio of 20 mol% or less are preferable.
In the polymer constituting the fine fiber, it is preferable to suppress the inclusion of components other than the biocompatible polymer.

  As a method for producing a suture, a process of producing a precise sea-island type composite fiber having an average island fiber diameter of 10 to 1000 nm and having an island number of 100 or more, a yarn-spinning process, a twisting / twisting process, a sea component In general, there are four processes, such as a process of eluting or decomposing sucrose. Here, the order of the four steps is not particularly limited, except that a step of eluting or decomposing sea components is provided after the step of manufacturing the sea-island composite fiber. The twisting / twisting step may be performed either 1) before the step of eluting or decomposing the sea component, or 2) after the step of eluting or decomposing the sea component. What is necessary is just to use properly. The order of the combined yarn process is not particularly limited as long as the sea-island type composite fiber is manufactured. The number of combined yarns may be appropriately adjusted according to the JIS suture standard.

  In the twisting step, it is preferable to twist at 50 to 1000 T / M. More preferably, it is 100-800 T / M. If the number of twists is less than 50 T / M, the fine fibers are scattered and the handleability may be poor. On the other hand, if it exceeds 1000 T / M, the handleability may be poor due to the lack of flexibility inherent to fine fibers. Furthermore, when the twisting / twisting process is performed before the sea component dissolution / decomposition and removal process, unevenness in sea component dissolution / decomposition / removal may cause unevenness in quality as sutures. is there.

  That is, a preferred method for producing the suture of the present invention is as follows: 1) After sea-island type composite fibers having an easily soluble component in a specific solvent as a sea component and a hardly soluble component as an island component are combined, the sea-island type composite fiber is converted into a sea component. Or a process comprising a step of twisting at 50 to 1000 T / M, or 2) 50 to 1000 T of a sea-island type composite fiber having an easily soluble component in a specific solvent as a sea component and a hardly soluble component as an island component. This is a production method including a step of extracting and removing sea components from sea-island type composite fibers after twisting at / M. Here, the island component is the above-described biocompatible thermoplastic resin.

  A method for producing the sea-island type composite fiber will be described. The sea-island ratio is not particularly limited, but the sea-island ratio is preferably in the range of 10:90 to 80:20, and particularly preferably in the range of sea: island = 10: 90 to 70:30. If the proportion of the sea component is 70% or more, the amount of the solvent necessary for dissolving the sea component increases, which causes problems in terms of safety, environmental load, and cost. Moreover, when it is less than 10%, islands may be stuck.

  The number of islands is preferably 100 or more. The greater the number of islands, the higher the productivity in producing fine fibers by dissolving and removing sea components. Here, when the number of islands is less than 100, a fine fiber having a small fiber diameter cannot be obtained even if the sea component is dissolved and removed, so that it may not be a suture with excellent flexibility as the object of the present invention. . In particular, the number of islands is preferably 500 or more. The upper limit of the number of islands is not particularly limited, but it is preferably set to 1000 or less because not only the manufacturing cost of the spinneret increases, but also the processing accuracy itself tends to decrease.

In the step of eluting or decomposing the sea component, it is preferable to remove the sea component almost completely.
The necessary conditions for the sea polymer and the island polymer may be any as long as the following two points are satisfied. The two points are as follows: 1) The melt viscosity of the sea component during melt spinning is higher than the melt viscosity of the island component. 2) In the dissolution rate in the specific solvent, the dissolution rate of the sea component is 200 with respect to the dissolution rate of the island component. It is more than double.

  When the melt viscosity of the sea component at the time of melt spinning is higher than the melt viscosity of the island component, the sea-island cross-section formability is improved. If this condition is satisfied, even if the composite weight ratio of the sea components is 50% or less, the islands will not adhere to each other and become different from the sea-island fibers. When islands are stuck together, when sea components are dissolved and removed, not only fine fibers but also deformed fibers are created, and problems such as dyed spots and pilling are likely to occur. A particularly preferred melt viscosity ratio (sea / island) is in the range of 1.1 to 2.0, particularly 1.3 to 1.5. If this ratio is less than 1.1, the island components are likely to stick together during melt spinning, whereas if it exceeds 2.0, the difference in viscosity is too large and the spinning tone tends to decrease.

  In addition, here, the easily soluble component and the hardly soluble component are one polymer that elutes or decomposes under the same dissolution condition with respect to the two polymers forming the sea-island composite fiber, and the other polymer It means selecting a solvent that is not easily eluted or decomposed, or selecting a combination of such polymers and selecting its readily soluble component as a sea component. When the dissolution rate of the sea component is 200 times or more with respect to the dissolution rate of the island component, the island separation property is improved. When the dissolution rate ratio is less than 200 times, the island component of the separated fiber cross-section surface layer is dissolved because the fiber diameter is small while the sea component at the center of the fiber cross-section is dissolved. Despite being reduced, the sea component at the center of the fiber cross-section cannot be completely dissolved and removed, resulting in variations in the quality of the sutures due to unevenness in the thickness of the island components and deterioration in tensile strength due to solvent erosion. Since it becomes large, the handleability deteriorates.

  The sea polymer may be any polymer as long as it satisfies the above-mentioned two points, but polyester, polyamide, polystyrene, polyethylene, and the like having good fiber formation are particularly preferable. For example, polylactic acid, ultra-high molecular weight polyalkylene oxide condensation polymer, and copolymerized polyester of 5-sodium sulfoisophthalic acid are optimal as the alkaline water soluble polymer. Here, the alkaline aqueous solution refers to potassium hydroxide, sodium hydroxide aqueous solution and the like. Nylon 6 is dissolved in formic acid, and polystyrene is dissolved in an organic solvent such as toluene.

  The sea polymer must have a melt viscosity higher than that of the island component at the time of melt spinning, and any dissolution rate ratio between the island component and the sea component in the solvent or the degradable drug can be 200 or more. Polymers may be used, but particularly preferable examples include polyesters, aliphatic polyamides, and polyolefins such as polyethylene and polystyrene, which have good fiber-forming properties. Specific examples include polylactic acid, ultra-high molecular weight polyalkylene oxide condensation polymer, polyethylene glycol compound copolymer polyester, polyethylene glycol compound and 5-sodium sulfoisophthalic acid copolymer as an easily soluble polymer in aqueous alkali solution. Polyethylene terephthalate is optimal. Here, the alkaline aqueous solution refers to potassium hydroxide, sodium hydroxide aqueous solution and the like. Besides these, hydrocarbon solvents such as hot toluene and xylene for formic acid for aliphatic polyamides such as nylon 6 and nylon 66, trichloroethylene for polystyrene, and polyethylene (especially high-pressure low-density polyethylene and linear low-density polyethylene). Examples thereof include hot water for polyvinyl alcohol and ethylene-modified vinyl alcohol polymers.

  Among the polyester polymers, copolymer polyethylene terephthalate containing 5 to 12 mol% of 5-sodium sulfoisophthalic acid in the total dicarboxylic acid component and 3 to 10 wt% of polyethylene glycol having a molecular weight of 4000 to 12000 in the total polymer is preferable. The intrinsic viscosity of the copolymerized polyethylene terephthalate is preferably 0.4 to 0.6. Here, 5-sodium sulfoisophthalic acid contributes to improving hydrophilicity and melt viscosity, and polyethylene glycol (PEG) improves hydrophilicity. In addition, PEG has a hydrophilicity increasing action that is considered to be due to its higher-order structure as the molecular weight increases. However, since the reactivity becomes poor and a blend system is produced, problems arise in terms of heat resistance and spinning stability. there is a possibility. On the other hand, when the copolymerization amount of polyethylene glycol exceeds 12% by weight, there is an effect of decreasing the melt viscosity, which is not preferable. From the above, it is considered that the above range is appropriate. When the copolymerized polyethylene terephthalate is used as a sea component, it is preferably removed almost completely, and the residual amount is preferably 3% by weight or less.

  The island polymer is selected from biocompatible thermoplastic resins that have a lower viscosity than the sea component viscosity during melt spinning and have a difference in dissolution rate from the sea component as described above. Preferred biocompatible thermoplastic resins are as described above. Preferably, aromatic polyesters, such as polyethylene terephthalate, polytrimethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, and aromatic dicarboxylic acids such as isophthalic acid and 5-sulfoisophthalic acid metal salt having these as the main repeating units, A copolymer with an aliphatic dicarboxylic acid such as adipic acid or sebacic acid, or a hydroxycarboxylic acid condensate such as ε-caprolactone, or a glycol component such as diethylene glycol, trimethylene glycol, tetramethylene glycol or hexamethylene glycol is preferred. In particular, aromatic polyesters such as polyethylene terephthalate, polytrimethylene terephthalate, polybutylene terephthalate, and polyethylene terephthalate isophthalate and polyethylene naphthalate having an isophthalic acid copolymerization ratio of 20 mol% or less are preferable.

  Furthermore, the island component is not limited to a round cross section, and may be an irregular cross section. As the die used for melt spinning, an arbitrary one such as a hollow pin group or a fine hole group for forming an island component can be used. For example, a spinneret may be used in which an island component extruded from a hollow pin or a fine hole and a sea component flow that is designed to fill the gap between the island component are joined and compressed to form a cross section of the sea island. . Examples of spinnerets that are preferably used are shown in FIGS. 1 and 2, but are not necessarily limited thereto.

FIG. 1 shows a method of discharging a hollow pin into a sea component resin reservoir and compressing it by joining, and FIG. 2 shows a method of forming an island by a fine hole method.
The discharged sea-island type composite fiber is solidified by cooling air and taken up by a rotating roller or an ejector set at a predetermined take-up speed to obtain an undrawn yarn. The take-up speed is not particularly limited, but is desirably 800 m / min to 5000 m / min. Productivity is poor at 800 m / min or less. Also, spinning stability is poor at 5000 m / min or more.

  The obtained unstretched yarn is stretched according to the intended tensile strength, elongation, and heat shrinkage properties according to the purpose and purpose of the fine fiber obtained after extracting the sea component. Alternatively, a separate stretching method in which stretching is performed in separate steps may be used, or a straight stretching method in which stretching is performed immediately after spinning in one process may be used.

  One of the unprecedented features is that the fiber of the present invention has a large specific surface area. For this reason, it has excellent adsorption and absorption characteristics. Taking advantage of this effect, for example, a functional drug can be absorbed to develop a new application. Examples of functional drugs include drugs for promoting health and beauty such as proteins and vitamins, and other drugs such as anti-inflammatory agents and disinfectants.

Hereinafter, the present invention will be described more specifically with reference to examples. Each evaluation item was measured by the following method.
1) Melt viscosity measurement The polymer after drying is set in an orifice set at the melter melting temperature at the time of spinning, melted and held for 5 minutes, then extruded under several levels of load, and the shear rate and melt viscosity at that time are determined. Plot. By gently connecting the plots, a shear rate-melt viscosity curve is created, and the melt viscosity when the shear rate is 1000 sec- ¹ is observed.

2) Sea-island cross-section formation The sea-island state was observed using an optical microscope and evaluated in two stages.
○: No island sticking part ×: Island sticking part

3) Measurement of dissolution rate The yarn is wound at a spinning speed of 1000 to 2000 m / min with a 0.3φ-0.6L × 24H base of each of the sea and island components, and the residual elongation is in the range of 30 to 60%. Then, a multifilament of 83 dtex / 24 fil is produced. The weight loss rate was calculated from the dissolution time and the dissolution amount at a bath ratio of 100 at a temperature at which the solvent was dissolved in each solvent.
In the table, the case where the sea-island dissolution rate difference was 200 times or more was marked with ◯, and the case where it was 200 times or less was marked with ×.

4) Fiber diameter of fine fiber and uniformity of diameter The fiber diameter was determined by 30,000 times TEM observation of the fine fiber after dissolution and removal of the sea component. Here, the fiber diameter of the single yarn that was not glued was measured. In the fiber diameter data of 50 randomly selected fine fibers, the average fiber diameter (X) and the standard deviation (σ) were calculated, and the fiber diameter variation coefficient (CV) defined below was calculated.
Fiber diameter variation coefficient (CV) = σ / X

5) Tensile strength and elongation of fine fiber The fine fiber after dissolution and removal of the sea component was measured n = 3 times to obtain the fineness from the average value.
At room temperature (25 ° C.), an initial sample length = 200 mm, a pulling speed = 200 mm / min, and a load-elongation curve was obtained under the conditions shown in JIS L1013. Next, a value obtained by dividing the load value at break by the initial fineness was taken as the tensile strength, and the elongation value at break was taken as the elongation to obtain a strong elongation curve.

6) Nodule strength Nodule strength was measured in accordance with the above-described tensile strength test method in the state where one Z-twisted main knot was formed at the center of the gripping interval of the fine fibers after dissolution removal of the sea component.

7) Number of twists Fine fibers with a test length of 10 cm were measured with an n = 5 times twisting twister, and the number of twists was determined from the average value.

8) Flexibility / Handability Seven monitors were evaluated using actual thread.
○: More than half of monitors felt flexible and easy to handle ×: More than half of monitors felt inflexible or poorly handled

[Example 1]
The island component was copolymerized with polyethylene terephthalate having a melt viscosity at 285 ° C. of 1200 poise, and the sea component was copolymerized with 3 wt% of polyethylene glycol having an average molecular weight of 4000 having a melt viscosity of 1400 poise at 285 ° C. and 9 mol% of 5-sodium sulfoisophthalic acid. The modified polyethylene terephthalate was melt-spun at 285 ° C. using a base having 900 islands at a ratio of sea: island = 30: 70, and wound up at 1000 m / min. Here, the alkali weight loss rate difference of the sea component with respect to the island component was 1500 times. The obtained undrawn yarn was subjected to roller drawing at a drawing temperature of 60 to 90 ° C. and the magnification described in Table 2, and then heat-set at 150 ° C. and wound up. At this time, the spinning discharge amount was adjusted so that the drawn yarn was 22 dtex / 10f. This drawn yarn was knitted in a cylinder, and the sea component ratio equivalent was dissolved with a solvent. When the cross section of the raw yarn was observed by TEM, the sea-island cross-section formation was good. After four drawn yarns drawn at a draw ratio of 5.1 times were combined, the sea component was reduced by 30% at 95 ° C. with a 4% NaOH aqueous solution. Observation of the fiber cross section revealed that ultrafine islands with a fiber diameter of 450 nm and a CV value of 0.15 were formed. The fine fiber was twisted at 300 T / M, and then set with steam at 75 ° C. for 30 minutes. The tensile strength of the yarn is 5.2 cN / dtex, the elongation is 20%, the knot strength is 3.4 cN / dtex, and the twist number is 290 T / M. It was. A scanning electron micrograph of the fine fibers obtained in Example 1 is shown in FIG. The results are shown in Tables 1 and 2.

[Comparative Example 1]
A process for producing a sea-island type composite fiber in the same manner as in Example 1 except that the sea-island type composite fiber was twisted at 20 T / M using a base having 1100 islands, a step of eluting sea components, A yarn was obtained through a twisting and twisting process. When the cross section of the fiber was observed, the fiber diameter of the isolated island was 390 nm, but unevenness in the dissolution / decomposition and removal of the sea component occurred, so that a CV value = 0.4 and a non-uniform fine fiber group was formed. It was. The obtained fine fiber group had a tensile strength of 2.0 cN / dtex, an elongation of 15%, and a knot strength of 1.2 cN / dtex, which was good as flexibility, but poor in handling properties as a suture, The quality variation was large. The results are shown in Tables 1 and 2.

[Example 2]
After changing the order of Example 1 and the twisting / twisting step and combining four drawn yarns obtained by producing sea-island type composite fibers in the same manner as Example 1, twisting at 300 T / M, Thereafter, it was set with steam at 75 ° C. for 30 minutes. The obtained yarn was reduced by 30% with a 4% NaOH aqueous solution at 95 ° C. When the cross section of the fiber was observed, a uniform ultrafine island group having a fiber diameter of 440 nm and a CV value = 0.14 was formed. The fine fiber has a tensile strength of 5.2 cN / dtex, an elongation of 35%, a knot strength of 3.3 cN / dtex, and a twist number of 320 T / M. Thread was obtained. The results are shown in Tables 1 and 2.

[Comparative Example 2]
Except that the sea-island type composite fiber was twisted at 1500 T / M, the process of producing the sea-island type composite fiber was performed in the same manner as in Example 2, the process of combining, the process of twisting and twisting, and the process of eluting sea components. I got a thread. When the cross section of the fiber was observed, a non-uniform ultrafine island group having a fiber diameter of 460 nm and a CV value = 0.35 was formed. The obtained yarn had good tensile strength of 4.6 cN / dtex and elongation of 40%, but the knot strength was as weak as 1.0 cN / dtex, so that the handleability was poor as a suture. Furthermore, since the sea components are unevenly dissolved and decomposed, the quality of the sutures varies greatly. The results are shown in Tables 1 and 2.

[Example 3]
A yarn was obtained in the same manner as in Example 2 except that the sea-island type composite fiber was twisted at 700 T / M. Observation of a uniform and uniform fiber cross section after reducing the sea component by 30% revealed that a uniform ultrafine island group having a fiber diameter of 455 nm and a CV value = 0.12 was formed. The tensile strength of the yarn is 4.6 cN / dtex, the elongation is 60%, the knot strength is 2.8 cN / dtex, and the twist number is 730 T / M. It was. The results are shown in Tables 1 and 2.

[Comparative Example 3]
A yarn was obtained in the same manner as in Example 2 except that spinning was performed using a base having sea: island = 90: 10 and 500 islands. Observing the fiber cross-section after 90% reduction of the sea component, it takes time to reduce the sea part, so the island near the surface is excessively reduced, the fiber diameter is 210nm, and the CV value = 1.0 is uneven. A super-thin island group was formed. The fine fiber was twisted at 100 T / M, and then set with steam at 75 ° C. for 30 minutes. The tensile strength of the yarn is 1.2 cN / dtex, the elongation is 85%, the knot strength is 0.8 cN / dtex, and the twist number is 80 T / M. The handling was poor and poor. Furthermore, since the sea components are unevenly dissolved and decomposed, the quality of the sutures varies greatly. The results are shown in Tables 1 and 2.

[Comparative Example 4]
In Comparative Example 4, the number of islands was 25 and the single yarn diameter was 2500 nm. Compared with Comparative Example 3, the island component was more non-uniform and the island diameter was large, so the yarn was poor in flexibility. The results are shown in Tables 1 and 2.

[Example 4]
Polyethylene terephthalate having a melt viscosity of 1050 poise at 285 ° C. is used as the island component, 3% by weight of polyethylene glycol having an average molecular weight of 4000 having a melt viscosity of 1150 poise at 285 ° C. is used as the sea component, and 10 mol of 5-sodium sulfoisophthalic acid. % -Copolymerized modified polyethylene terephthalate was spun at a weight ratio of sea: islands = 30: 70 using a base having 700 islands (same type as in FIG. 1), and taken up at 3500 m / min. The alkali weight loss rate difference was 2000 times. After four drawn yarns drawn at a draw ratio of 3.0 times were combined, the sea component was reduced by 30% at 95 ° C. with a 4% NaOH aqueous solution. Observation of the fiber cross section revealed that ultrafine islands having a fiber diameter of 500 nm and a CV value = 0.15 were formed. The fine fiber was twisted at 400 T / M and then set with steam at 75 ° C. for 30 minutes. The tensile strength of the yarn is 3.2 cN / dtex, the elongation is 30%, the knot strength is 2.4 cN / dtex, and the twist number is 380 T / M. It was. The results are shown in Tables 1 and 2.

[Comparative Example 5]
Polyethylene terephthalate having a melt viscosity of 1050 poise at 285 ° C. is used for the island component, polyethylene glycol having an average molecular weight of 4000 having a melt viscosity of 950 poise at 285 ° C. is used for the sea component, and 10 mol of 5-sodium sulfoisophthalic acid. It was wound up in the same manner as in Example 4 using% -copolymerized modified polyethylene terephthalate. When the cross section of the raw yarn was observed with a TEM, the melt viscosity of the sea component polymer was smaller than that of the island component, so that 90% or more of the island components were joined together and did not exist individually. An enclosing cross section was formed. Therefore, even if the sea component is removed by alkali weight reduction, a fine fiber group cannot be formed, and the yarn has poor flexibility. The results are shown in Tables 1 and 2.

[Example 5]
Polyethylene terephthalate having a melt viscosity at 270 ° C. of 600 poise is used as the island component, and polylactic acid having a D-form purity of 99% and melt viscosity at 270 ° C. of 1750 poise is used as the sea component. Spinning was performed using a die having the number of islands of 500 (same type as that in FIG. 1) at a weight ratio of 80, and taken up at 1000 m / min to obtain an undrawn yarn. The alkali weight loss rate difference was 1000 times. After stretching this 2.2 times, 10 yarns were combined. In order to dissolve and remove only the sea component, this was reduced by 20% at 95 ° C. with a 4% NaOH aqueous solution. When the cross section of the fiber was observed, a uniform ultrafine island group having a fiber diameter of 600 nm and a CV value of 0.1 was formed. The obtained yarn was twisted at 500 T / M and then set with steam at 75 ° C. for 30 minutes. The tensile strength of the yarn is 2.1 cN / dtex, the elongation is 40%, the knot strength is 1.8 cN / dtex, and the twist number is 490 T / M. It was. The results are shown in Tables 1 and 2.

[Example 6]
Nylon 6 having a melt viscosity of 1150 poise at 285 ° C. is used for the island component, 3% by weight of polyethylene glycol having an average molecular weight of 4000 having a melt viscosity of 1300 poise at 285 ° C. and 8 mol of 5-sodium sulfoisophthalic acid are used for the sea component % Copolymerized modified polyethylene terephthalate, spun at a weight ratio of sea: island = 30: 70 using a base with the number of islands of 1000 (same type as in FIG. 1), taken up at 1000 m / min, and undrawn yarn Got. Here, since nylon 6 which is an island component does not substantially dissolve in an alkaline solution, there is a sufficient sea-island dissolution rate difference. When the drawn yarn obtained at a draw ratio of 2.9 times was subjected to a dissolution treatment in formic acid in which only the modified polyethylene terephthalate of the sea was dissolved at room temperature, nylon 6 as an island component was substantially dissolved in formic acid. Therefore, since there was a sufficient difference in sea island dissolution rate, the uniformity of the island components was good, the fiber diameter was 400 nm, and the CV value = 0.09. The obtained yarn was twisted at 600 T / M and then set with steam at 75 ° C. for 30 minutes. The tensile strength of the yarn was 2.9 cN / dtex, the elongation was 45%, the knot strength was 2.0 cN / dtex, and the twist number was 580 T / M. Twenty multifilaments made of the fine fibers obtained were combined to prepare a yarn. Yarns having flexibility unique to fine fibers and good handleability were obtained. The results are shown in Tables 1 and 2.

[Example 7]
The bundle of three yarns obtained in Example 1 (tensile strength 3.7 cN / dtex, elongation 27.2%, knot strength 2.7 cN / dtex) was used as one suture, as follows: Animal evaluation was performed.
Animal; Guinea pig (Hartley, male) 27wk, weight 1100g
Anesthesia; Ketamine + xylazine (intramuscular administration)
The suture was immersed in 70% EtOH for 25 minutes, washed with running ultrapure water, and autoclaved (121 ° C, 20 minutes).

  After general anesthesia of the guinea pig, the back was shaved and the skin was incised to 1 to 2 cm, and two places were sewn with test threads. The flexibility and knot strength of the thread were satisfactory and it was good to handle as a suture. After completion of the stitching, it was returned to the gauge and reared normally. On the 7th day after the operation, the sutured part was observed with the naked eye. As a result, no pulling was observed, and no noticeable inflammation was observed. FIG. 4 shows photographs of macroscopic findings at the skin suture site on the seventh day after the operation.

Example of spinneret. Example of spinneret. 2 is a scanning electron micrograph of the fine fiber bundle obtained in Example 1. FIG. An appearance photograph on the seventh day after the suturing of Example 7. 6 is a micrograph of a tissue stained image at a skin suture site in Example 7. FIG.

Claims (10)

It is made of a biocompatible thermoplastic resin, is made of a fine fiber bundle having an average fiber diameter of 10 to 1000 nm obtained by removing sea components from sea-island type composite fibers , has a tensile strength of 1.5 cN / dtex or more, and a knot strength of 1. A suture having 5 to 6.0 cN / dtex and a twist number of 50 to 1000 T / M.   The suture according to claim 1, wherein the biocompatible thermoplastic resin is selected from polyesters, polyamides, and polyolefins.   The suture according to claim 2, wherein the biocompatible thermoplastic resin is an aromatic polyester. The suture according to any one of claims 1 to 3, wherein a fiber diameter variation coefficient (CV) defined below is 0 to 0.3.
Fiber diameter variation coefficient (CV) = σ / X
(The fiber diameter is the average value of the major axis and minor axis in the fiber cross section, σ is the standard deviation of the fiber diameter distribution, and X is the average fiber diameter.) The suture according to any one of claims 1 to 4, wherein the tensile strength is 7.0 cN / dtex or less.   An easily soluble component in a specific solvent is a sea component, a hardly soluble component is an island component, the island component is a biocompatible thermoplastic resin, and the average diameter (r) of the island component in the cross section of the composite fiber is The method for producing a suture according to any one of claims 1 to 5, wherein an island component is obtained by extracting and removing a sea component from a sea-island type composite fiber having 10 to 1000 nm and having 100 or more islands.   At least one alkali selected from the group consisting of polylactic acid, ultra-high molecular weight polyalkylene oxide condensation polymer, polyethylene glycol compound copolymer polyester, and polyethylene glycol compound and 5-sodium sulfoisophthalic acid copolymer polyethylene terephthalate The method for producing a suture according to claim 6, which is an aqueous solution easily soluble polymer.   The sea component is a copolymerized polyethylene terephthalate containing 5 to 12 mol% of 5-sodium sulfoisophthalic acid in the total dicarboxylic acid component and 3 to 10 wt% of polyethylene glycol having a molecular weight of 4000 to 12000 in the total polymer. A method for producing the suture as described.   After combining the sea-island type composite fiber with the sea component as the easily soluble component in the specific solvent and the island component as the hardly soluble component, the sea component is extracted and removed from the sea-island type composite fiber and twisted at 50 to 1000 T / M. The manufacturing method of the suture in any one of Claims 6-8 including a process.   A process comprising extracting a sea component from a sea-island type composite fiber after twisting a sea-island type composite fiber having an easily soluble component in a specific solvent as a sea component and a hardly soluble component as an island component at 50 to 1000 T / M. Item 9. A method for producing a suture according to any one of Items 6 to 8.

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