STRUCTURE REINFORCING MATERIAL

Abstract

The present invention aims to provide a tissue reinforcement material having water absorbency and high stretchability. Provided is a tissue reinforcement material including a non-woven fabric containing polyglycolide, wherein the tissue reinforcement material has an average fiber diameter of 0.5 .Math.m or more and 7.0 .Math.m or less, an areal density of 1.0 g/m.sup.2 or more and 50 g/m.sup.2 or less, and a flexural rigidity (B value) measured with a pure bending tester of 0.001 gf.square-solid.cm.sup.2/cm or more and 0.01 gf.square-solid.cm.sup.2/cm or less.

Claims

1. A tissue reinforcement material comprising a non-woven fabric containing polyglycolide, wherein the tissue reinforcement material has an average fiber diameter of 0.5 .Math.m or more and 7.0 .Math.m or less, an areal density of 1.0 g/m.sup.2 or more and 50 g/m.sup.2 or less, and a flexural rigidity (B value) measured with a pure bending tester of 0.001 gf.Math.cm.sup.2/cm or more and 0.01 gf.Math.cm.sup.2/cm or less.

2. The tissue reinforcement material according to claim 1, having a rigidity of 0.1 N/mm or more and 3.0 N/mm or less.

3. The tissue reinforcement material according to claim 1, having a thickness of 30 .Math.m or more and 300 .Math.m or less.

4. A method of producing the tissue reinforcement material according to claim 1, comprising: producing a non-woven fabric containing polyglycolide by a melt blowing method; and needle punching the non-woven fabric, wherein in the producing the non-woven fabric, a distance between a nozzle and a conveyor is 15 cm or more and 80 cm or less and a nozzle temperature is not lower than a melting point of the polyglycolide + 20° C. and not higher than the melting point of the polyglycolide + 50° C.

5. The method of producing the tissue reinforcement material according to claim 4, wherein in the producing the non-woven fabric, the distance between the nozzle and the conveyor is 20 cm or more and 60 cm or less.

6. The method of producing the tissue reinforcement material according to claim 4, wherein in the producing the non-woven fabric, the nozzle temperature is not lower than the melting point of the polyglycolide + 30° C. and not higher than the melting point of the polyglycolide + 40° C.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0045] FIG. 1 shows photographs of evaluation samples after tissue expansion and contraction in an evaluation of conformability to the movements of a biological tissue.

[0046] FIG. 2 shows photographs of tissue reinforcement materials obtained in examples magnified 100-fold using an electron microscope.

DESCRIPTION OF EMBODIMENTS

[0047] The following will describe embodiments of the present invention in detail, but the present invention should not be limited to these embodiments.

Example 1

[0048] Thread containing polyglycolide (weight average molecular weight: 120000, melting point: 223° C., glass transition point: 41° C.) was discharged by a melt blowing method to prepare a non-woven fabric having a thickness of 120 .Math.m. Specific conditions for the melt blowing were as follows: a distance between the nozzle and the conveyor of 30 cm, a polymer discharge amount of 0.1 kg/h, an air velocity near the discharge outlet of 3000 m/min, a conveyor travel speed of 1.0 m/min, and a nozzle temperature of 260° C. Subsequently, the obtained non-woven fabric was needle punched to prepare a tissue reinforcement material.

Comparative Example 1

[0049] A tissue reinforcement material was produced as in Example 1 except that needle punching was not performed.

Comparative Example 2

[0050] A tissue reinforcement material was produced as in Example 1 except that the distance between the nozzle and the conveyor was 10 cm, and that needle punching was not performed.

Reference Example 1

[0051] A commercially available bioabsorbable non-woven fabric (NEOVEIL NV-L-015G, produced by Gunze Ltd.) containing polyglycolide was used as it was.

[0052] NEOVEIL NV-L-015G is a 220-.Math.m-thick bioabsorbable non-woven fabric produced by needle punching.

Physical Properties

[0053] The tissue reinforcement materials obtained in the example, the comparative examples, and the reference example were subjected to the following measurements. Table 1 shows the results.

Measurement of Average Fiber Diameter

[0054] A measurement sample (1.0 cm .sub.X 1.0 cm) was cut out from the center of the obtained tissue reinforcement material. An image of the obtained measurement sample magnified 3000-fold was captured using a scanning electron microscope (SEM). From the obtained image, 10 fiber potions were randomly selected, and the fiber diameter was measured. The results were averaged to determine the average fiber diameter.

Measurement of Areal Density

[0055] Three sheets (5.0 cm .sub.X 5.0 cm) were cut out from the center of the obtained tissue reinforcement material to prepare measurement samples. The areal density of each of the obtained measurement samples was measured using an analytical balance (AUX220, produced by SHIMADZU Corporation), and the average of the measurement results was used as the areal density of the tissue reinforcement material.

Measurement of Flexural Rigidity (B Value)

[0056] A measurement sample (10 cm .sub.X 10 cm) was cut out from the center of the obtained tissue reinforcement material. The flexural rigidity (B value) of the obtained measurement sample was measured using a pure bending tester (KES-FB2-A produced by Kato Tech Co., Ltd.).

Measurement of Rigidity

[0057] Three sheets (2.0 cm .sub.X 5.0 cm) were cut out from the obtained tissue reinforcement material such that the MD of the tissue reinforcement material corresponded to the short sides to prepare measurement samples. Each of the obtained measurement samples was subjected to a tensile test using a compact table-top tester (AG-Xplus, produced by SHIMADZU Corporation) at 23° C., a chuck distance of 20 mm, and a tensile speed of 10 mm/sec to measure the rigidity when the sample was stretched from 0.5 mm (2.5%) to 1 mm (5%). The average of the measurement results was used as the rigidity of the tissue reinforcement material.

Evaluation

[0058] The tissue reinforcement materials obtained in the example, the comparative examples, and the reference example were evaluated for the following items. The results of the evaluation of stretchability and the evaluation of absorbency were shown in Table 1. The results of the evaluation of conformability to the movements of a biological tissue were shown in FIG. 1.

Evaluation of Stretchability

[0059] Five sheets (2.0 cm .sub.X 5.0 cm) were cut out from the tissue reinforcement material such that the MD of the tissue reinforcement material corresponded to the short sides to prepare measurement samples. Each of the obtained measurement samples was tested using a compact table-top tester (AG-Xplus, produced by SHIMADZU Corporation) to measure the elongation at the maximum tenacity from the tensile strength and the percentage of elongation in conformity with JIS L-1912. The results were averaged to evaluate stretchability.

Evaluation of Water Absorbency

[0060] In conformity with the water retention test specified in JIS L-1913, three sheets (100 mm .sub.X 100 mm) were cut out from the center of the material to prepare measurement samples, and the mass of each measurement sample before the test was measured using an analytical balance (AUX220, produced by SHIMADZU Corporation). Subsequently, each measurement sample was immersed in water in a container for 15 minutes and taken out of the water to let the water drip off for one minute. The mass after the test was then measured. Based on the results, the water retention was calculated using the following equation, and the results of the three samples were averaged to evaluate water absorbency.

[00001]$\begin{array}{l}\text{Water}\text{retention}\text{W}\text{(\%)=((W1-W0)/W0)×100}\\ \text{(W0:}\text{mass}\text{before}\text{the}\text{test,}\text{W1:}\text{mass}\text{after}\text{the}\text{test)}\end{array}$

Evaluation of Conformability to the Movements of Biological Tissue

[0061] An evaluation sample (50 mm .sub.X 30 mm) was cut out from the center of the obtained tissue reinforcement material. Subsequently, the sample was gently placed on the liver of a sacrificed pig and pressed lightly several times from above with a moisturized gauze to wet the sample and attach the sample closely. The operation of expanding and contracting the liver about 20% was performed three times, and conformability to the movements was evaluated based on whether the sample separated from the liver. FIG. 1 shows photographs of the evaluation samples after expansion and contraction. FIG. 1 demonstrates that the evaluation sample of Example 1 did not separate from the liver, whereas the evaluation samples of Comparative Examples 1 and 2 partially lifted and separated from the liver. The sample of Reference Example 1 did not separate from the liver, but the sample of Example 1 was more firmly adhered.

[0062] FIG. 2 shows photographs of the tissue reinforcement material obtained in the examples magnified 100-hold with an electron microscope (Miniscope TM-1000, produced by Hitachi High-Technologies Corporation). The image on the left shows the top surface of the tissue reinforcement material, and the image on the right shows a cross section. As clearly seen from FIG. 2, the material of Example 1 has a smaller average fiber diameter, a smaller areal density, and more gaps between fibers than the material of Reference 1 which is a conventional bioabsorbable non-woven fabric. The material of Example 1 thus has high water absorbency. It also has stretchability because the number of contact points between fibers is small. Furthermore, owing to needle punching of the non-woven fabric produced by melt blowing, the material of Example 1 also has increased flexibility, and thus has further improved adhesion to fine irregularities as well as further increased stretchability and water absorbency. In addition, owing to the small average fiber diameter, the material is preferable for a scaffold for cell proliferation and provides high tissue regenerating properties.

[0063] In contrast, the materials of Comparative Example 1 and Comparative Example 2, not subjected to needle punching, have lower adhesion to fine irregularities, lower stretchability, and lower water absorbency than the material of Example 1 even though they have a small average fiber diameter and a small areal density as the material of Example 1.

[0064] The material of Reference Example 1 has stretchability because, being produced by needle punching, it has non-fixed contact points between fibers and also because the number of contact points is small. However, the material of Reference Example 1 has a large average fiber diameter. Bioabsorbable non-woven fabrics having a small average fiber diameter have higher adhesion to fine irregularities and higher tissue regenerating properties.

TABLE-US-00001 Example 1 Comparative Example 1 Comparative Example 2 Reference Example 1 Physical properties Average f ber diameter (.Math.m) 2.7 2.8 2.4 14.2 Areal density (g/m.sup.2) 9.7 10.1 11.7 27.9 Flexural rigidity (B value) (gf.sup..cm.sup.2/cm) 0.0049 0.0153 0.0187 0.0177 Rigidity (N/mm) 1.3 3.53 3.37 0.1 Evaluation Stretchability (%) 68 35 23 220 Water absorbency (water retention) (%) 2559 1151 591 664

INDUSTRIAL APPLICABILITY

[0065] The present invention can provide a tissue reinforcement material having water absorbency and high stretchability.