JPH09140785A - Biodegradable film for medical treatment and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it possible to simultaneously satisfy plural requirement characteristics which are difficult to be embodied with a single material by laminating plural sheets of biodegradable films varying in the degradation characteristics and/or physical characteristics in a living body, thereby constituting the biodegradable film. SOLUTION: This biodegradable film for medical treatment having a three- layered structure is formed by arranging, for example, a relatively hard layer 2 on the inner side and arranging relatively soft layers 1, 3 on both sides thereof. A film of a copolymer consisting of about 65mol% L-lactide an about 35mol% ε-caprolatone and having about 100μm thickness is used for the layer 2. Films of a copolymer consisting of about 80mol% L-lactide and about 20mol% ε-caprolactone and having about 100μm thickness are used for the layers 1, 3. A laminate film having about 100μm thickness is formed by thermal press. The laminate may be formed to layers exclusive a three layers, for example, to five layers when formed to ι2 layers.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a biodegradable medical film and a method for producing the same. For more information,
TECHNICAL FIELD The present invention relates to a biodegradable medical film having improved properties and a method for producing the same.

[0002]

2. Description of the Related Art Biodegradable medical materials have been used for a long time as sutures because they function after being operated for a certain period of time and then gradually decomposed and absorbed by the living body. Examples of such biodegradable materials include collagen, chitin, oxidized cellulose, polyglycolic acid, polylactide, a copolymer of hydroxybutyric acid and hydroxyvaleric acid, poly-p-
Dioxanone and the like are known.

However, such biodegradable materials are also
It has not been used much for applications other than sutures. In particular, the sheet-like material is only slightly used in some limited applications, and it does not have satisfactory properties. The reason is,
This is because it is difficult to obtain a material that simultaneously satisfies the required physical properties and decomposition properties. That is, a material having physical properties satisfying the requirements has unsatisfactory decomposition properties, and a material having favorable decomposition properties has unsatisfactory physical properties.

[0004]

Generally, when used in a living body in the form of a film, it is preferably flexible. However, the flexible material cannot maintain its shape for a necessary period because of its high decomposition rate and shrinkage of the film. On the contrary, many materials that are slowly decomposed are hard, which is not preferable because they give irritation when they come into contact with a living body.

For example, a copolymer of D, L-lactide and ε-caprolactone is known as a flexible material at a temperature of about body temperature, but this film is decomposed in a relatively short period of time and the film shrinks. It becomes difficult to maintain the shape. On the other hand, a film of polyglycolic acid or polylactide, which decomposes relatively slowly, lacks flexibility and is not preferable. As described above, the lack of a material that simultaneously satisfies two types of required properties has hindered the development of biodegradable materials for various applications.

An object of the present invention is to provide a biodegradable film and a method for producing the same, which solves such problems. That is, the present invention provides a biodegradable film having properties that are difficult to realize with a single material.

[0007]

In the present invention, by laminating two or more kinds of films having different characteristics,
The above objective has been achieved. That is, the medical film of the present invention is characterized by laminating two or more biodegradable films having different in vivo degradability and / or physical properties. The method for producing a biodegradable medical film of the present invention is characterized by laminating films having different in vivo degradability and / or physical properties to produce a film having desirable properties. .

Although it is not clear why a film having excellent characteristics can be obtained by the present invention, by laminating films having different characteristics, the preferable characteristics of each film are maintained as they are, and the unfavorable characteristics are diluted. It is estimated that this is because of the reason.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The biodegradable film used in the present invention is preferably composed of a synthetic polymer because it is easy to process and a film having arbitrary characteristics can be easily obtained. Examples of suitable synthetic polymers include copolymers composed of any component selected from glycolic acid, L-lactide, D, L-lactide and ε-caprolactone, and homopolymers thereof. it can. These polymers can be obtained by a known method.

Among the above polymers, glycolic acid and L-
Homopolymer of lactide, copolymer of glycolic acid and L-lactide or D, L-lactide, copolymer of glycolic acid or L-lactide and ε-caprolactone, and glycolic acid-L-lactide-ε- Since caprolactone copolymer and the like decompose relatively slowly, they are preferable in terms of decomposition characteristics. However, since the obtained film is relatively hard at a temperature around body temperature, it is not preferable to use it alone in a living body.

On the other hand, a copolymer of D, L-lactide and ε-caprolactone has good flexibility at a temperature of about body temperature and is therefore preferably used as a flexible film layer. Particularly preferred is D, L-lactide of 60-9.
It is a copolymer containing 0 mol% and ε-caprolactone in the range of 30 to 10 mol%. A film made of such a copolymer is excellent in flexibility, but when implanted alone in a living body, the strength thereof is rapidly lowered and the film shrinks.

When laminating the above-mentioned films, as shown in FIG. 1, a three-layer structure in which a relatively hard layer 2 is disposed on the inner side and relatively flexible layers 1 and 3 are disposed on both sides thereof is used. preferable. With such a structure, it is possible to obtain a laminated film which is flexible and does not decompose rapidly. In addition to the three-layer structure, as shown in FIG. 2, flexible layers 4 and 8 are provided on both sides, and two hard layers 5 are provided inside the layers.
It is also possible to have a five-layer structure in which 7 and one flexible layer 6 are alternately laminated.

The thickness of each layer to be laminated may be the same or different. In the case of laminating the flexible layer and the hard layer, if the flexible layer is made thick and the hard layer is made thin, a more flexible laminated film having good decomposition characteristics can be obtained. The preferable thickness of the film varies depending on the use, but a laminated film having a thickness of about 30 to 500 μm is preferable.

The laminated film of the present invention can be produced by producing a film of a single component constituting each layer, laminating these films and hot pressing to a desired thickness. It is also possible to manufacture each layer in a single step by simultaneously extruding the layers from a molding machine and laminating the layers.

[0015]

EXAMPLES The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples.

Example 1 L-lactide 65 mol% and ε
Copolymer film consisting of 35 mol% of caprolactone (thickness: about 100 μm), D and L, one from each side
-Lactide 80 mol% and ε-caprolactone 20 mol%
It was sandwiched between the copolymer films (having a thickness of about 100 μm) and was hot pressed to produce a laminated film having a thickness of about 100 μm. When the physical properties of the obtained film were measured at 37 ° C., as shown in Table 1, the film had a low elastic modulus and was flexible.

Next, Table 1 shows the results of immersing this film in a physiological saline solution at 37 ° C. and measuring its physical properties at 37 ° C. every week. As can be seen from the table, the film retained its morphology after 8 weeks and remained flexible.

[0018]

[Table 1]

[Embodiment 2] In the same manner as in Embodiment 1, L-
One film of a copolymer consisting of 65 mol% of lactide and 35 mol% of ε-caprolactone was used, and two mols of D, L-lactide and 80 mol of ε-caprolactone were prepared from each side.
It was sandwiched by a copolymer film composed of mol% and hot-pressed to produce a laminated film having a thickness of about 100 μm. That is, this laminated film was prepared by comparing D, L- with the film 1 made of the L-lactide-ε-caprolactone copolymer.
A film composed of a lactide-ε-caprolactone copolymer is laminated at a ratio of 4.

The resulting film, as shown in Table 2,
It was even more flexible than that obtained in Example 1. Further, similarly, when it was immersed in a physiological saline solution at 37 ° C. and its physical properties were measured once a week, as shown in Table 2,
It remained flexible for more than 6 weeks and was flexible.

[0021]

[Table 2]

[Comparative Example 1] 65 mol% of L-lactide and ε
-From a copolymer of 35 mol% caprolactone, a thickness of about 1
A film of 00 μm was produced. This film is 37
As a result of measuring the physical properties at ° C, as shown in Table 3, it was considerably harder than those obtained in the examples. Table 3 shows the results obtained by immersing the film in a physiological saline solution at 37 ° C. and examining changes in physical properties.

[0023]

[Table 3]

Comparative Example 2 D, L-lactide 80 mol%
A film having a thickness of about 100 μm was prepared from the copolymer of 20 mol% of ε-caprolactone. This film was highly flexible as shown in Table 4, but at 37 ° C.
When it was dipped in the physiological saline solution, the film contracted after 3 weeks, which was a problem for achieving a long-term function in vivo.

[0025]

[Table 4]

As can be seen from the above Examples and Comparative Examples, even if the film is too hard alone or has a high decomposition rate and cannot function in a living body for a long period of time, the flexibility is maintained by laminating both. It is possible to obtain a film that can function for a long period of time.

[0027]

According to the present invention, by laminating biodegradable films having different properties, it is possible to obtain a film in which the advantages of each film are maintained and the disadvantages thereof are eliminated. In particular, by laminating a hard film that is slowly decomposed but a film that is flexible but rapidly decomposed, it is possible to produce a film that is flexible and slowly decomposed, so that it functions for a long time without stimulating the living body. It is suitable as a film for implantation in a living body. An adhesion prevention film is typical as such an application, and exhibits excellent functions in other applications such as organ protection and prosthesis.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing an example of a biodegradable medical film of the present invention.

FIG. 2 is a cross-sectional view showing another embodiment of the biodegradable medical film of the present invention.

[Explanation of symbols]

 1,3,4,6,8 Flexible layer 2,5,7 Hard layer

Claims (10)

[Claims] 1. A medical film comprising a stack of two or more biodegradable films having different in vivo degradability and / or physical properties. 2. The medical film according to claim 1, wherein the physical property is flexibility. 3. The medical film according to claim 2, wherein a layer having a relatively slow decomposition in a living body and being inferior in flexibility and a layer having a relatively rapid decomposition and being flexible are laminated. 4. The medical film according to claim 3, wherein one or more layers having relatively slow decomposition in a living body and poor flexibility are provided inside, and the outermost layer is composed of a flexible layer having relatively rapid decomposition. 5. The medical film according to claim 4, wherein a layer having relatively low decomposition in vivo and poor flexibility is present in the center, and a flexible layer having relatively rapid decomposition is laminated on both sides thereof. . 6. A layer which is relatively slow in vivo degrading and inferior in flexibility is composed of an L-lactide-ε-caprolactone copolymer, and a layer which is relatively fast degrading in flexibility is D, L-lactide-.
The medical film according to any one of claims 3 to 5, which comprises an ε-caprolactone copolymer. 7. The medical film according to claim 1, wherein the medical film is an adhesion prevention film. 8. A method for producing a biodegradable medical film, which comprises laminating films having different in vivo degradability and / or physical properties to produce a film having preferable properties. 9. The method for producing a biodegradable medical film according to claim 8, wherein the physical property is flexibility. 10. The method for producing a biodegradable medical film according to claim 9, wherein a layer having a relatively slow decomposition in a living body and inferior flexibility and a layer having a relatively rapid decomposition and a flexible layer are laminated. Method.