COMPOSITE THREAD AND MANUFACTURE PROCESS THEREOF

Abstract

A composite thread including a core thread and at least one wrapping film is provided. The wrapping film wraps the core thread uniformly. The composite thread is mainly formed by the biodegradable material, and has improved biocompatibility which is suitable to be used in the surgery. A manufacture process thereof is also provided.

Description

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the priority benefit of Taiwan application serial no. 103116544, filed on May 9, 2014. The entirety of the above-mentioned patent application is hereby incorporated by reference herein and made a part of this specification.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to a thread and a manufacturing process thereof, and particularly relates to a biodegradable composite thread and a manufacturing process thereof.

2. Description of Related Art

Generally speaking, threads are commonly used in surgeries to sew organs such as blood vessels, viscera, and skin, etc. Since the materials and characteristics of threads influence how the threads are treated after surgeries, the development on the materials of threads becomes an important issue. Based on the structures of the materials, the threads may be divided into single-strand threads and multi-strand threads. Based on the sources of the materials, the threads may be divided into natural threads and synthetic threads. In addition, based on the absorbability of the threads, the threads may be divided into absorbable threads and unabsorbable threads.

The unabsorbable threads are not degradable, so the threads need to be removed after being used. On the contrary, the absorbable threads are degradable. When used to sew a cut, the absorbable threads may be absorbed by the human body after a period of time, and is thus not necessary to be removed. Accordingly, the absorbable threads are nowadays commonly used in surgeries that require sewing. The absorbable threads have a preferable biocompatibility and appropriate tensile strength, which improve the safety as well as convenience in the surgery. Besides, it is preferred that the threads has a preferable surface sliding characteristics, so that after the threads pass through the organs or are knotted, the friction force generated when fixing the tissues is reduced as much as possible.

SUMMARY OF THE INVENTION

The invention provides a composite thread and a manufacturing method thereof. The composite thread has biodegradability and is suitable to be implanted into an organism and capable of generating a specific effect.

A composite thread of the invention includes a core thread and at least one wrapping film. In addition, the wrapping film wraps a surface of the core thread.

A manufacturing method of a composite thread of the invention includes manufacturing steps as follows: providing a core thread formed of a plurality of line segments connected in series; continuously immersing the core thread into a first wrapping film solution and removing the core thread from the first wrapping film solution, wherein each of the line segments of the core thread is removed from the first wrapping film solution after the next line segment is immersed into the first wrapping film solution; obtaining the core thread wrapped by a first wrapping film by performing a first drying step; continuously immersing the core thread wrapped by the first wrapping film into a second wrapping film solution and removing the core thread wrapped by the first wrapping film from the second wrapping film solution, wherein each of the line segments of the core thread is removed from the second wrapping film solution after the next line segment is immersed into the second wrapping film solution; and obtaining a composite thread wrapped by a second wrapping film by performing a second drying step.

A composite thread of the invention is manufactured by manufacturing steps as follows: providing a core thread formed of a plurality of line segments connected in series; continuously immersing the core thread into a first wrapping film solution and removing the core thread from the first wrapping film solution, wherein each of the line segments of the core thread is removed from the first wrapping film solution after the next line segment is immersed into the first wrapping film solution; obtaining the core thread wrapped by a first wrapping film by performing a first drying step; continuously immersing the core thread wrapped by the first wrapping film into a second wrapping film solution and removing the core thread wrapped by the first wrapping film from the second wrapping film solution, wherein each of the line segments of the core thread is removed from the second wrapping film solution after the next line segment is immersed into the second wrapping film solution; and obtaining a composite thread wrapped by a second wrapping film by performing a second drying step.

Based on the above, the composite thread of the invention is formed of a biodegradable material, and may thus be absorbed by an organism. Therefore, the composite thread has a preferable biocompatibility and is suitable to be partially or completely implanted into an organism. When the composite thread is used in a surgery, the composite thread may have the function of sewing and repairing organs such as skin, blood vessels and viscera, etc. In addition, the component in the wrapping film on the composite thread may be spread to the surrounding tissues to achieve an additional assisting function.

To make the above features and advantages of the invention more comprehensible, embodiments accompanied with drawings are described in detail as follows.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification. The drawings illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention.

FIG. 1 is a block diagram illustrating a manufacturing process of a composite thread according to an embodiment of the invention.

FIG. 2 is a flow chart illustrating a manufacturing process of a composite thread according to an embodiment of the invention.

FIG. 3 is a cross-sectional schematic view of a composite thread according to an embodiment of the invention.

FIG. 4 is a schematic view illustrating a coating machine according to an embodiment of the invention.

FIG. 5A is a view of a polydioxanone (PDO) thread under an electron microscope.

FIG. 5B is a view of a composite thread wrapped with a first wrapping film under an electron microscope.

FIG. 5C is a view of a composite thread wrapped with a second wrapping film under an electron microscope.

FIG. 5D is a view illustrating degradation of a composite thread after 28 days of in vitro test.

FIG. 6 illustrates a relation between weight loss rates and a degradation time of the composite threads in Examples 1-4.

FIG. 7 illustrates a relation between pH values and a degradation time in the in vitro degradation test of the composite threads in Examples 1-4.

FIG. 8 illustrates a test outcome of a cell survival rate of each test sample.

FIG. 9 illustrates a test outcome of a cell survival rate of each test sample.

DESCRIPTION OF THE EMBODIMENTS

Reference will now be made in detail to the present preferred embodiments of the invention, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers are used in the drawings and the description to refer to the same or like parts.

FIG. 1 is a block diagram illustrating a manufacturing process of a composite thread according to an embodiment of the invention. FIG. 2 is a flow chart illustrating the manufacturing process of the composite thread according to the embodiment. Referring to FIGS. 1 and 2, Step S10 is firstly performed. A core thread 102 formed of a plurality of line segments connected in series is provided. In other words, the core thread 102 is a continuous thread formed by connecting the plurality of line segments.

The core thread 102 may be formed of a biodegradable polymer selected from a group consisting of polyester, polysaccharide, polyamino acid, the copolymers thereof, the blends thereof, and the mixtures thereof, for example. More specifically, the core thread 102 is selected from a group consisting of poly-glutamic acid, polylysine, polyorthoester, polycaprolactone, polylactide, polyglycolic acid, poly(sebacic acid) polyanhydride, polydioxanone, chitin, fucoidan, the copolymers thereof, the blends thereof, and the mixtures thereof, for example. A biodegradable polymer may be gradually degraded by being absorbed by an organism. Therefore, the biodegradable polymer may be present in the organism for a specific period of time.

Then, Step S20 is performed. The core thread 102 is continuously immersed into a first wrapping film solution 204a and removed from the first wrapping film solution 204a. In addition, each of the line segments of the core thread 102 is removed from the first wrapping film solution 204a after the next line segment is immersed into the first wrapping film solution 204a.

The first wrapping film solution 204a is a solution having a bioactive component, for example. The bioactive component is selected from a group consisting of anti-inflammatory agents, analgesic agents, anesthetic agents, antihistamines, steroids, skin-lightening medicaments, diabetes medicaments, cell growth factors, natural moisture-retaining factors, nucleic acids, peptides, proteins, vitamins, antilipidemic medicaments, anti-cholesterol medicaments, growth hormones, hormones, antioxidizing medicaments, cell growth inhibitors, and differentiation inhibitors, for example.

Specifically, the core thread 102 may be wound on a feeding thread shaft 202A, for example. The core thread 102 may be sequentially disposed on a plurality of rotation shafts and transported by using the rotation shafts. For example, a first rotation shaft 202a may be disposed in the first wrapping film solution 204a, and a second rotation shaft 202b may be disposed outside the first wrapping film solution 204a. By rotating the first rotation shaft 202a, the core thread 102 may be continuously rolled into the first wrapping film solution 204a. In this way, the first wrapping film solution 204a is coated on a surface of the core thread 102. The second rotation shaft 202b may then continuously pull the core thread 102 out of the first wrapping film solution 204a. The first rotation shaft 202a and the second rotation shaft 202b may have the same rotating speed. A thickness of the first wrapping film solution 204a on the core thread 102 may be determined by adjusting the rotating speed. In addition, when transporting the core thread 102, the core thread 102 may have a tensile force due to pulling of the first rotation shaft 202a and the second rotation shaft 202b. In this way, the first wrapping film solution 204a may adhere to the core thread 102 more uniformly, and the usage of the first wrapping film solution 204a may be reduced.

Then, Step S30 is performed. The core thread 102 coated with a first wrapping film 104 is obtained by performing a first drying step. Specifically, by using the second rotation shaft 202b, the core thread 102 coated with the first wrapping film solution 204a is transported to a heating tube H1 for a heating step, so as to remove a solvent in the first wrapping film solution 204a and obtain the first wrapping film 104 that is approximately cured. The first wrapping film 104 wraps a surface of the core thread 102. A temperature in the heating step is approximately between 55° C. to 65° C.

Then, Step S40 is performed. The core thread 102 wrapped by the first wrapping film 104 is continuously immersed into a second wrapping film solution 204b and removed from the second wrapping film solution 204b. In addition, each of the line segments of the core thread 102 is removed from the second wrapping film solution 204b after the next line segment is immersed into the second wrapping film solution 204b.

The second wrapping film solution 204a is a solution having a slowly biodegradable component, for example. The slowly biodegradable component is selected from a group consisting of poly-glutamic acid, polylysine, polyorthoester, polycaprolactone, polylactide, polyglycolic acid, polysebacic polyanhydride, polydioxanone, chitin, fucoidan, the copolymers thereof, the blends thereof, and the mixtures thereof, for example.

For example, a third rotation shaft 202c may be disposed in the second wrapping film solution 204b, and a fourth rotation shaft 202d may be disposed outside the second wrapping film solution 204b. By rotating the third rotation shaft 202c, the core thread 102 may be continuously immersed into the second wrapping film solution 204b. In this way, the second wrapping film solution 204b is coated on the surface of the core thread 102. The fourth rotation shaft 202d may then continuously pull the core thread 102 out of the second wrapping film solution 204b. The third rotation shaft 202c and the fourth rotation shaft 202d may have the same rotating speed. A thickness of the second wrapping film solution 204b on the core thread 102 may be determined by adjusting the rotating speed. In addition, an additional rotation shaft may be disposed between the rotation shafts, so as to determine a transporting direction and allow the manufacturing process to proceed smoothly. The invention is not limited thereto. When transporting the core thread 102, the core thread 102 may have a tensile force due to pulling of the third rotation shaft 202c and the fourth rotation shaft 202d. In this way, the second wrapping film solution 204b may adhere to the core thread 102 more uniformly, and the usage of the second wrapping film solution 204b may be reduced.

Then, Step S50 is performed. The core thread 102 coated with a second wrapping film 106 is obtained by performing a second drying step. Specifically, by using the fourth rotation shaft 202d, the core thread 102 coated with the second wrapping film solution 204b is transported to a heating tube H2 for a heating step, so as to remove a solvent in the second wrapping film solution 204b and obtain the second wrapping film 106 that is approximately cured. The second wrapping film 106 covers a surface of the first wrapping film 104. A temperature in the heating step is approximately between 45° C. to 55° C. After the manufacturing process above, the composite thread 100 is approximately completed. For an illustrative purpose, the composite thread 100 of this embodiment is described as having a plurality of layers (e.g. two layers) of wrapping films, for example. However, the invention is not limited thereto. In other embodiments, the composite thread 100 may include only one layer of wrapping film, such as the first wrapping film 104 having a bioactive component.

FIG. 3 is a cross-sectional schematic view of a composite thread according to an embodiment of the invention. Referring to FIGS. 2 and 3, the composite thread 100 includes the core thread 102, the first wrapping film 104, and the second wrapping film 106. The first wrapping film 104 wraps the surface of the core thread 102. The second wrapping film 106 wraps the surface of the first wrapping film 104, and the first wrapping film 104 is located between the core thread 102 and the second wrapping film 106.

Specifically, the composite thread 100 is biodegradable. Therefore, the composite thread 100 is suitable to be used as a surgical thread in a surgery. In addition, it is not necessary to remove the stitches when using the composite thread 100. Besides, the diameter of the composite thread 100 of the invention may be designed in a range between 0.05-0.7 mm. The size of the composite thread 100 is small and suitable to be implanted into an organism to facilitate the organism to activate a self-repairing process. For example, when the composite thread 100 is implanted into a lower layer of dermis at a plurality of points in a plurality of direction through stitches, a three-dimensional mesh structure may be formed to provide more support the skin. In addition, the wound of stitches and the composite thread 100 together trigger minor acute reaction and prompt the repairing mechanism of the skin, which release a plurality of growth factors and stimulates the generation of collagen to facilitate the metabolism of the skin and improve the skin quality.

More specifically, the first wrapping film 104 of the composite thread 100 contains a bioactive component that may be released to the organism to achieve an additional assisting effect such as skin-lightening and anti-oxidizing, etc. The second wrapping film 106 contains a slowly biodegradable component having the effect of slowing down spreading, such as slowing down the speed that the bioactive component is spread in the organism, so as to elongate the overall release time of the bioactive component and achieve the function of controlling the release accordingly. In this embodiment, the core thread 102 and the second wrapping film 106 are biodegradable, for example. In addition, the degradation time of the core thread 102 may be longer than the degradation time of the second wrapping film 106. In this way, the second wrapping film 106 may be completely degraded before degradation of the core thread 102 is completed, so as to release the bioactive component in the first wrapping film 104 as much as possible. It should be noted that the composite thread 100 of the invention is described as having two layers of wrapping films for an illustrative purpose. However, the invention is not limited thereto. In other embodiments, a similar coating process or other processes may be performed to manufacture two or more layers of wrapping films, such that the composite thread 100 may have a more variety of composite effects.

FIG. 4 is a schematic view illustrating a coating machine according to an embodiment of the invention. Referring to FIG. 4, a coating machine 200 includes the feeding thread shaft 202A, a receiving thread shaft 202B, a plurality of rotation shafts 202, a plurality of heating tubes H, and a plurality of lifting tables 206. The core thread 102 is wound on the feeding thread shaft 202A, and the core thread 102 may be disposed on the plurality of rotation shafts 202. A transporting path of the core thread 102 may be designed by disposing the rotation shafts. A coating solution 204 may be disposed on the lifting tables 206. The lifting tables 206 may adjust the height of the coating solution 204. In this way, the transporting path of the core thread 102 may pass through the coating solution 204. In addition, the transporting path of the core thread 102 passes through the heating tube H, so as to obtain a coating layer by removing a solvent in the coating solution 204. After coating at least two coating layers, the composite thread that is manufactured may be wound on the receiving thread shaft 202B. Here, the method described herein is to form a wrapping film on the core thread 102 by coating. However, the invention is not limited thereto.

Examples 1 and 2 are described below to illustrate the invention. However, the invention is not limited thereto.

The core thread is a biodegradable material, which may be absorbed after being embedded into an organism for a period of time. The core thread itself and the product after the core thread is degraded are compatible with cells, and unlikely to induce negative reactions such as an irritative reaction, a foreign body reaction, or an oncogenic reaction, etc.

In Example 1, the core thread was formed of polydioxanone (PDO), for example. When a PDO thread is embedded into the skin, the thread is capable of promoting microcirculation in local tissues, activating reparative processes of cells, and stimulating collagen production.

In Example 1, the bioactive component is vitamin C having a skin lightening effect, for example. A preparation method of the first wrapping film solution is provided below. First of all, 10 g of Polyvinylpyrrolidone (PVP) and 50 g of vitamin C were mixed and placed into a beaker having a capacity of 250 ml. Then, 100 ml of deionized water was added. Then, the solution was heated at 37° C. on a heating board and stirred until all solid bodies were completely dissolved. The vitamin C solution as the first wrapping film solution was thus prepared. The concentration of the vitamin C solution is between 25 wt % and 35 wt %.

The slowly biodegradable component was poly(lactide-co-glycolide) acid (PLGA) copolymer, for example. In addition, a ratio between lactide (LA) and glycolide (GA) was 75:25. A preparation method of the second first wrapping film solution is provided below. First of all, 11 g of the PLGA copolymer having an inherent value (I.V.) at 0.4 was placed into a beaker having a capacity of 250 ml. Then, 100 ml of dichloromethane was added. The solution was then stirred until all solid bodies were completely dissolved. The PLGA copolymer solution, as the second wrapping film solution, is thus prepared. The concentration of the PLGA copolymer solution is about 10 wt %.

The first heating tube of the coating machine was heated to 60° C. in advance. The second heating tube was heated to 50° C. in advance. The first coating film solution was placed below the first heating tube, and the second coating film solution was placed below the second heating tube. Afterwards, the speed of the receiving thread shaft was set at 0.3 rpm, and the receiving thread shaft started to rotate. At this time, the PDO thread passed through the first wrapping film solution and then the solvent was baked dry by the first heating tube to form the first wrapping film. Then, the PDO thread passed through the second wrapping film solution, and then the solvent was baked dry by the second heating tube to form the second wrapping film. Finally, the receiving thread shaft collected the composite thread that was manufactured. The time duration that the PDO thread is absorbed by the human body is approximately 180 to 240 days. The time duration that the PLGA copolymer wrapping film is absorbed by the human body is about 28 days.

The manufacturing process described in Example 2 is similar to that described in Example 1, but the bioactive component in Example 2 is different from that in Example 1. In Example 2, the bioactive component was vitamin E having an anti-oxidizing effect, for example. A preparation method of the first wrapping film solution is provided below. First of all, 10 g of Polyvinylpyrrolidone (PVP) and 50 g of vitamin E were mixed and placed into a beaker having a capacity of 250 ml. Then, 100 ml of methylene chloride was added. Then, the solution was stirred until all solid bodies were completely dissolved. The vitamin E solution as the first wrapping film solution was thus prepared. The concentration of the vitamin E solution is between 25 wt % and 35 wt %.

The composite thread of Example 3 is similar to that of Example 1. The bioactive components in Examples 1 and 3 were Vitamin C. However, Example 3 differs from Example 1 in that the inherent value of the PLGA copolymer in Example 3 was 0.8. The composite thread of Example 4 is similar to that of Example 2. The bioactive components in Examples 2 and 4 were Vitamin E. However, Example 4 differs from Example 2 in that the inherent value of the PLGA copolymer in Example 4 was 0.8.

FIG. 5A is a view of a polydioxanone (PDO) thread under an electron microscope. FIG. 5B is a view of a composite thread wrapped with a first wrapping film under an electron microscope. FIG. 5C is a view of a composite thread wrapped with a second wrapping film under an electron microscope. FIG. 5D is a view illustrating degradation of a composite thread after 28 days of the in vitro test. Referring to FIG. 5A, before coating of the active component (i.e. without the first wrapping film), there were a plurality of strip-like cracks on a lateral surface of the thread. Referring to FIG. 5B, after the first wrapping film was formed, the lateral surface of the composite thread became more complete. Referring to FIG. 5C, after the second wrapping film was formed, a plurality of pores were formed on the lateral surface of the composite thread. The pores were formed when the solvent (e.g. dichloromethane) in the PLGA copolymer wrapping film solution having a viscosity to a certain degree (e.g. I.V. at 0.4) was evaporated when the solution was heated. Referring to FIG. 5D, it is shown that after 28 days of the in vitro test, the second wrapping film was degraded, and the biodegradability of the second wrapping film is thus shown. Since the second wrapping film is slowly degraded within a period of time, the component of the first wrapping film may be slowly released to the body of an organism, so as to control the bioactive component to be slowly released.

A degradation test on the composite threads of Examples 1-4 are described below. The test procedure is described as follows. First of all, the composite threads that were weighted were placed in test tubes. Then, 5 ml of normal saline (phosphate buffer saline, PBS) having a pH value at 7.4 was added to the test tubes where the samples are placed. Then, the test tubes were placed in a thermostatic tank having a temperature set at 37° C. After a fixed period of time, the samples were taken out to be dried and weighted. Then, pH values of the liquids in the test tubes were measured.

FIG. 6 illustrates a relation between weight loss rates and a degradation time of the composite threads in Examples 1-4. As shown in FIG. 6, the longer the degradation duration time was, the lower the weight of each of the composite threads became, indicating that the first wrapping film and the second wrapping film on the composite threads were gradually peeled off through time.

FIG. 7 illustrates a relation between pH values and a degradation time in the in vitro degradation test of the composite threads in Examples 1-4. Referring to FIG. 7, as the second wrapping film was gradually dissolved, the PLGA copolymer was gradually released to the liquids in the test tubes. Therefore, the pH values gradually dropped.

The in vitro test of cell survival rate on a plurality of composite threads is described below. The test described herein was conducted in accordance with the standard of ISO 10993-5. The test samples included a PDO composite thread coated with a wrapping film having 8 wt % of vitamin C, a PDO composite thread coated with a wrapping film having 15 wt % of vitamin C, a PDO composite thread coated with a wrapping film having 4 wt % of vitamin E, and a PDO composite thread coated with a wrapping film having 8 wt % of vitamin E. In addition, a blank control group (incubated with 5 ml of the minimum essential medium (MEM) culture medium containing bovine serum), a negative control group (a PE film, extracted at 37° C. for 24 hours at the ratio of 6 cm²/mL), and a positive control group (incubated with 0.2% of phenol) were also included.

The used MEM extracts were prepared in accordance with the standard of ISO 10993-12. The test samples were mixed with the MEM extracts at the ratio of 6 cm²/mL. Then the MEM extracts were used to extract the test samples at 37° C. for 24 hours, so as to obtain an extract of each of the test samples. Then, the extract of each of the test samples was co-cultured with a mouse fibroblast strain L929 (NCTC clone 929) for 72 hours under a condition of 5% of CO₂ at 37° C. Then, a MTT assay, a quantitative analysis, was performed to test the cell survival rate. FIG. 8 illustrates a test outcome of the cell survival rate of each test sample. As shown in FIG. 8, the composite thread of the invention had a higher cell survival rate, indicating that the composite thread of the invention has a higher biocompatibility.

In addition, the same test was performed on different test samples to test the in vitro cell survival rate. Here, the test samples included a PDO thread coated with 31 wt % of the vitamin C wrapping film and PLGA copolymer wrapping film and a PDO thread coated with 31 wt % of the vitamin E wrapping film and PLGA copolymer wrapping film. FIG. 9 illustrates a test outcome of the cell survival rate of each test sample. From the experiments, for the test samples using the composite thread of the invention, at least 80 percent of cell viability was observed.

In view of the foregoing, the composite thread of the invention is formed of a biodegradable material, and may thus be absorbed by an organism. Therefore, the composite thread of the invention has a preferable biocompatibility and is suitable to be partially or completely implanted into an organism. When the composite thread is used in a surgery, the composite thread may have the function of sewing and repairing organs such as skin, blood vessels, and viscera, etc. In addition, the component in the wrapping film on the composite thread may be spread to the surrounding tissues to achieve an additional assisting function.

It will be apparent to those skilled in the art that various modifications and variations can be made to the structure of the present invention without departing from the scope or spirit of the invention. In view of the foregoing, it is intended that the invention covers modifications and variations of this invention provided they fall within the scope of the following claims and their equivalents.

Claims

1. A composite thread, comprising:

a core thread; and

at least one wrapping film, wrapping a surface of the core thread.

2. The composite thread as claimed in claim 1, wherein the composite thread is formed of a biodegradable polymer.

3. The composite thread as claimed in claim 2, wherein the biodegradable polymer is selected from a group consisting of polyester, polysaccharide, polyaminoacid, the copolymers thereof, the blends thereof, and the mixtures thereof.

4. The composite thread as claimed in claim 2, wherein the biodegradable polymer is selected from a group consisting of poly-glutamic acid, polylysine, polyorthoester, polycaprolactone, polylactide, polyglycolic acid, polysebacic polyanhydride, polydioxanone, chitin, fucoidan, the copolymers thereof, the blends thereof, and the mixtures thereof.

5. The composite thread as claimed in claim 1, wherein at least one of the at least one wrapping film has a bioactive component.

6. The composite thread as claimed in claim 5, wherein the bioactive component is selected from a group consisting of anti-inflammatory agents, analgesic agents, anesthetic agents, antihistamines, steroids, skin-lightening medicaments, diabetes medicaments, cell growth factors, natural moisture-retaining factors, nucleic acids, peptides, proteins, vitamins, antilipidemic medicaments, anti-cholesterol medicaments, growth hormones, hormones, antioxidizing medicaments, cell growth inhibitors, and differentiation inhibitors.

7. The composite thread as claimed in claim 5, wherein the at least one wrapping film is a plurality of layers of wrapping films, and one of the wrapping film has a slowly biodegradable component.

8. The composite thread as claimed in claim 7, wherein the slowly biodegradable component is selected from a group consisting of poly-glutamic acid, polylysine, polyorthoester, polycaprolactone, polylactide, polyglycolic acid, polysebacic polyanhydride, polydioxanone, chitin, fucoidan, the copolymers thereof, the blends thereof, and the mixtures thereof.

9. A manufacturing process of a composite thread, comprising:

providing a core thread formed of a plurality of line segments connected in series;

continuously immersing the core thread into a first wrapping film solution and removing the core thread from the first wrapping film solution, wherein each of the line segments of the core thread is removed from the first wrapping film solution after the next line segment is immersed into the first wrapping film solution;

obtaining the core thread wrapped by a first wrapping film by performing a first drying step;

continuously immersing the core thread wrapped by the first wrapping film into a second wrapping film solution and removing the core thread wrapped by the first wrapping film from the second wrapping film solution, wherein each of the line segments of the core thread is removed from the second wrapping film solution after the next line segment is immersed into the second wrapping film solution; and

obtaining a composite thread wrapped by a second wrapping film by performing a second drying step.

10. The manufacturing process of the composite thread as claimed in claim 9, wherein the method of continuously immersing the core thread into the first wrapping film solution and removing the core thread from the first wrapping film solution comprises:

disposing a first rotation shaft in the first wrapping film solution, and continuously rolling the core thread into the first wrapping film solution by using the first rotation shaft; and

disposing a second rotation shaft outside the first wrapping film solution, and continuously removing the core thread from the first wrapping film solution by using the second rotation shaft.

11. The manufacturing process of the composite thread as claimed in claim 9, wherein the method of continuously immersing the core thread wrapped by the first wrapping film into the second wrapping film solution and removing the core thread wrapped by the first wrapping film from the second wrapping film solution comprises:

disposing a third rotation shaft in the second wrapping film solution, and continuously rolling the core thread wrapped by the first wrapping film into the second wrapping film solution by using the third rotation shaft; and

disposing a fourth rotation shaft outside the second wrapping film solution, and continuously removing the core thread from the second wrapping film solution by using the fourth rotation shaft.

12. The manufacturing process of the composite thread as claimed in claim 9, wherein the first drying step or the second drying step comprises a heating step.

13. A composite thread, manufactured by manufacturing steps as follows:

providing a core thread formed of a plurality of line segments connected in series;

continuously immersing the core thread into a first wrapping film solution and removing the core thread from the first wrapping film solution, wherein each of the line segments of the core thread is removed from the first wrapping film solution after the next line segment is immersed into the first wrapping film solution;

obtaining the core thread wrapped by a first wrapping film by performing a first drying step;

continuously immersing the core thread wrapped by the first wrapping film into a second wrapping film solution and removing the core thread wrapped by the first wrapping film from the second wrapping film solution, wherein each of the line segments of the core thread is removed from the second wrapping film solution after the next line segment is immersed into the second wrapping film solution; and

obtaining a composite thread wrapped by a second wrapping film by performing a second drying step.