Medical needles

Abstract

A medical needle (10) comprises a needle body (12), a hub (14) and a protector (16). The hub is made of a first resin composition. The protector has a needle covering part (50) that covers a part of the needle body. The needle covering part is made of a second resin composition. The first and second resin compositions each contain polyvinyl chloride and a trimellitic acid ester. In the first resin composition, the ratio of the trimellitic acid ester is 10-20 phr. In the second resin composition, the ratio of the trimellitic acid ester is 40-50 phr.

Description

[[TECHNICAL FIELD]]

[0001] The present invention relates to a medical needle comprising a needle body, a hub, and a protector. [[BACKGROUND ART]]

[0002] A blood collection needle is a type of medical needle. A blood collection needle is, for example, incorporated into a blood collection kit that collects blood from a blood donor (hereinafter also referred to as "donor"). In this case, the blood collection needle is connected to a bag via a tube. The blood collection needle comprises a hollow needle body, a hub, and a protector. A proximal end portion of the needle body in the longitudinal direction is inserted into the hub. A distal end of the needle body in the longitudinal direction is exposed from the hub. The distal end is inserted into a blood vessel of the donor.

[0003] The tube is connected to the hub. The proximal end portion of the needle body is connected to the tube via the hub. Accordingly, blood collected from the distal end of the needle body passes through the hollow interior of the needle body and flows into the tube. Blood passing through the tube flows into the bag.

[0004] As described in Japanese Examined Patent Publication No. 1-17381, in a blood collection needle before use, the protector is joined to the hub. Accordingly, the distal end exposed from the hub is covered by the protector. In other words, the distal end is protected by the protector. When collecting blood with the blood collection needle, a user performing blood collection twists the protector relative to the hub. As a result, the protector separates from the hub. The user pulls the separated protector away from the hub. This exposes the distal end of the needle body from the protector.

[0005] The material of each of the hub and the protector is a resin composition. In the resin composition, a plasticizer is added to the base resin. The plasticizer maintains the flexibility of the base resin. The base resin is, for example, polyvinyl chloride (PVC). In Japanese Examined Patent Publication No. 1-17381, phthalic acid esters, trimellitic acid esters, and the like are mentioned as suitable plasticizers when PVC is the base resin. [Overview of the Initiative]

[0006] Among phthalate esters, di-2-ethylhexyl phthalate (hereinafter referred to as "DEHP") has been widely used conventionally. In contrast, trimellitic acid esters have recently been increasingly adopted as plasticizers. However, according to the present inventors' diligent research, the properties exhibited by hubs and protectors made using trimellitic acid esters differ from those exhibited by hubs and protectors made using DEHP. In other words, simply substituting the plasticizer from DEHP to trimellitic acid ester does not easily yield the desired properties. For example, this presents the inconvenience of not being able to easily separate the protector from the hub. There is also a concern that the needle body may become misaligned relative to the hub.

[0007] The present invention aims to solve the problems described above.

[0008] According to one embodiment of the present invention, a medical needle is provided comprising a needle body, a hub supporting the proximal end of the needle body in the longitudinal direction, and a protector protecting the needle body, wherein the protector has a needle covering portion that covers the portion of the needle body exposed from the hub, the needle covering portion is detachably joined to the hub, the hub is made of a first resin composition, and the needle covering portion is made of a second resin composition, the first resin composition contains polyvinyl chloride and trimellitic acid ester, with a trimellitic acid ester ratio of 10 to 20 phr, and the second resin composition contains polyvinyl chloride and trimellitic acid ester, with a trimellitic acid ester ratio of 40 to 50 phr.

[0009] According to the present invention, a protector is obtained that has appropriate hardness, making it easy to transmit rotational torque. Therefore, the protector can be easily separated from the hub. In addition, the hub exhibits excellent retention force with respect to the needle body. As a result, concerns about the needle body shifting relative to the hub are eliminated. [Brief explanation of the drawing]

[0010] [Figure 1] Figure 1 is a perspective view of a blood collection needle, a type of medical needle. [Figure 2] Figure 2 is a longitudinal cross-sectional view of the main part of the blood collection needle. [Figure 3] Figure 3 is a graph showing the average rotational torque when the protector is separated from the hub. [Figure 4] Figure 4 is a graph showing the average tensile strength when the needle body is pulled out of the hub. [Figure 5] Figure 5 is a graph showing the average force required to attach and detach the protector from the hub. [Figure 6] Figure 6 shows the SAXS scattering curves obtained by performing small-angle X-ray scattering (SAXS) measurements on sample A and sample B. [Figure 7] Figure 7 is a chart showing the results of curve fitting for the SAXS scattering curve of sample A. [Figure 8] Figure 8 is a schematic diagram of an ideal crystal. [Figure 9] Figure 9 is a schematic diagram of an amorphous material. [Figure 10] Figures 10A and 10B are schematic diagrams of the tissue of sample A. [Figure 11] Figure 11 is a chart showing the results of curve fitting for the SAXS scattering curve of sample B. [Figure 12] Figures 12A and 12B are schematic diagrams of the tissue of sample B. [Figure 13] Figure 13 shows the WAXS scattering curves obtained by performing wide-angle X-ray scattering (WAXS) measurements on samples A and B. [Figure 14] Figure 14 is a peak separation analysis chart for the WAXS scattering curve of sample A. [Figure 15] Figure 15 is a peak separation analysis chart for the WAXS scattering curve of sample B. [Modes for carrying out the invention]

[0011] In the following, a blood collection needle is given as an example of a medical needle according to the present invention. However, the present invention is not particularly limited to a blood collection needle.

[0012] Figure 1 is a perspective view of the blood collection needle 10. Figure 2 is a longitudinal cross-sectional view of the main part of the blood collection needle 10. The blood collection needle 10 comprises a needle body 12, a needle hub 14 (hub), and a protector 16.

[0013] As shown in Figures 1 and 2, the needle body 12 is a small-diameter, elongated cylindrical body. The needle body 12 has a proximal end 20, which is one end in the longitudinal direction, and a tip 22, which is the other end in the longitudinal direction. An internal bore 24 is formed in the needle body 12. The internal bore 24 is a blood flow path and is a hollow interior that extends from the proximal end 20 to the tip 22. The formation of the internal bore 24 makes the needle body 12 a hollow body.

[0014] The base end 20 of the needle body 12 is inserted into the needle hub 14. Specifically, the needle hub 14 has a through hole 26 that extends along the axial direction of the needle hub 14. The through hole 26 extends from the tip surface of the distal end 28 of the needle hub 14 facing the needle body 12 to the protruding end surface of the projection 30. The through hole 26 includes an introduction hole 32, a retaining hole 34, and a communication hole 36. The introduction hole 32 opens at the tip surface of the distal end 28 of the needle hub 14. The retaining hole 34 is interposed between the introduction hole 32 and the communication hole 36.

[0015] The introduction hole 32 tapers in diameter from the proximal end 38 to the distal end 28 of the needle hub 14. The base end 20 of the needle body 12 is inserted through the introduction hole 32 and then pushed into the retaining hole 34. The base end 20 of the needle body 12 is joined to the inner wall of the retaining hole 34 via adhesive.

[0016] An insertion hole 40 is formed at the proximal end 38 of the needle hub 14. A cylindrical protruding portion 30 is provided on the bottom surface of the insertion hole 40. The protruding portion 30 protrudes toward the proximal end 38 of the needle hub 14. However, the entire protruding portion 30 is accommodated in the insertion hole 40. That is, the protruding portion 30 is not exposed from the insertion hole 40.

[0017] The distal end of a tube 42 is inserted into the insertion hole 40. The distal end of the tube 42 is fitted onto the protruding portion 30. An inner hole 44 of the tube 42 communicates with an inner hole 24 of the needle body 12 via a communication hole 36.

[0018] As shown in FIG. 1 and FIG. 2, the protector 16 is a hollow member. The protector 16 has an inner layer 50 and an outer layer 52. That is, the protector 16 has a double structure consisting of the inner layer 50 and the outer layer 52. The inner layer 50 is a needle covering portion that covers the needle body 12 in a shielding manner. In the needle body 12, the portion covered by the inner layer 50 is the portion exposed from the distal end 28 of the needle hub 14. In the needle body 12, the portion exposed from the distal end 28 of the needle hub 14 includes the tip 22. The outer layer 52 covers the inner layer 50. That is, the inner layer 50 is accommodated inside the outer layer 52. As such, the outer layer 52 is an outer covering portion.

[0019] Before the tube 42 is connected to the protruding portion 30 of the blood collection needle 10, a sealing film is affixed to the opening of the insertion hole 40. In this state, the blood collection needle 10 is sterilized by high-pressure steam. During this sterilization process, at least one of the inner layer 50 or the outer layer 52 of the protector 16 is bonded to the distal end 28 of the needle hub 14. Thereby, the space between the protector 16 and the needle hub 14 is sealed while the interior of the inner layer 50 (the accommodation space for the needle body 12) is maintained aseptic.

[0020] When using the blood collection needle 10, the user grasps the protector 16 with one hand and the needle hub 14 with the other hand. Next, the user twists either the protector 16 or the needle hub 14. As a result, the protector 16 and the needle hub 14 separate from each other, exposing the needle body 12. If necessary, the protector 16 is attached to the needle hub 14 so as to cover the needle body 12. In this case, the protector 16 is detachable from the needle hub 14.

[0021] In the above configuration, the needle hub 14 is made of the first resin composition. The inner layer 50 of the protector 16 is made of the second resin composition. The first and second resin compositions will now be described.

[0022] The first resin composition contains a base resin and a plasticizer. In this embodiment, the base resin is polyvinyl chloride (PVC). The plasticizer is a trimellitic acid ester. Specific examples of trimellitic acid esters include tributyl trimellitic acid or tris(2-ethylhexyl) trimellitic acid. Hereinafter, tris(2-ethylhexyl) trimellitic acid will also be referred to as "TOTM". The chemical structure of TOTM is shown below.

[0023] [ka]

[0024] In the first resin composition, the proportion of trimellitic acid ester is 10 to 20 phr. That is, when the weight of the base resin PVC is 100, the weight of trimellitic acid ester is 10 to 20. If the proportion of trimellitic acid ester is less than 10 phr, the hardness of the needle hub 14 will be high. Therefore, it will not be easy to separate the protector 16 from the needle hub 14. Also, it will not be easy to attach the protector 16 to the needle hub 14 after separating it from the needle hub 14. If the proportion of trimellitic acid ester exceeds 20 phr, the hardness of the needle hub 14 will be low. Therefore, there is a concern that the needle body 12 may be misaligned relative to the needle hub 14.

[0025] In other words, by setting the proportion of trimellitic acid ester to within the range of 10 to 20 phr, it is easy to separate the protector 16 from the needle hub 14 and to attach the protector 16 to the needle hub 14. Furthermore, the needle body 12 is firmly held by the needle hub 14. A more preferable proportion of trimellitic acid ester in the first resin composition is 13 to 18 phr.

[0026] The second resin composition contains a base resin and a plasticizer. In this embodiment, the base resin is PVC. The plasticizer is a trimellitic acid ester. Specific examples of trimellitic acid esters include tributyl trimellitic acid or TOTM.

[0027] In the second resin composition, the proportion of trimellitic acid ester is 40 to 50 phr. That is, when the weight of the base resin PVC is 100, the weight of trimellitic acid ester is 40 to 50. If the proportion of trimellitic acid ester is less than 40 phr, the hardness of the protector 16 will be high. Therefore, a large torque will be required when separating the protector 16 from the needle hub 14. If the proportion of trimellitic acid ester exceeds 50 phr, the hardness of the protector 16 will be low. Therefore, when the protector 16 is gripped, it will be slightly compressed. Also, when twisted relative to the needle hub 14, the joint will stretch. For these reasons, it is not easy to separate the protector 16 from the needle hub 14.

[0028] In other words, by setting the proportion of trimellitic acid ester to within the range of 40 to 50 phr, it is easy to separate the protector 16 from the needle hub 14. It is also easy to attach the separated protector 16 to the needle hub 14. A more preferable proportion of trimellitic acid ester in the second resin composition is 45 to 47 phr.

[0029] In this embodiment, the materials for the inner layer 50 and the outer layer 52 are the same second resin composition. That is, the proportion of trimellitic acid ester in the inner layer 50 and the outer layer 52 is the same. In this case, the fabrication of the protector 16 is easy. Alternatively, the proportion of trimellitic acid ester in the second resin composition of the inner layer 50 and the proportion of trimellitic acid ester in the second resin composition of the outer layer 52 may be different.

[0030] The material of the inner layer 50 and the material of the outer layer 52 may be different. In this case as well, the inner layer 50 is formed using the above-mentioned second resin composition as the material. Suitable specific examples of the material of the outer layer 52 include polyethylene or polycarbonate.

[0031] The blood collection needle 10 according to this embodiment is basically configured as described above. Next, the effects of the blood collection needle 10 will be explained.

[0032] The blood collection needle 10 is sterilized with high-pressure steam before use. During this sterilization process, at least one of the inner layer 50 or outer layer 52 of the protector 16 is joined to the distal end 28 of the needle hub 14.

[0033] When using the blood collection needle 10, the user connects the distal end of the tube 42 to the protrusion 30 of the needle hub 14. At this point, the proximal end of the tube 42 is connected to a bag (not shown). The user then grasps the protector 16 and the needle hub 14. Next, the user twists the protector 16 relative to the needle hub 14. As a result, the joint between the protector 16 and the needle hub 14 breaks. In other words, the protector 16 separates from the needle hub 14.

[0034] Here, the material of the needle hub 14 is the first resin composition described above. The material of the protector 16 is the second resin composition described above. When the needle hub 14 made of the first resin composition and the protector 16 made of the second resin composition are joined together, the protector 16 and the needle hub 14 can be easily separated with a small rotational torque.

[0035] As the protector 16 separates from the needle hub 14, the tip 22 of the needle body 12 is exposed from the protector 16. The user inserts the tip 22 of the needle body 12 into the patient's blood vessel. Blood is then collected from the blood vessel through the needle body 12. The blood flows into the bag through the inner hole 24 of the needle body 12, the communication hole 36 of the needle hub 14, and the inner hole 44 of the tube 42. After a predetermined amount of blood has been collected in the bag, the user withdraws the tip 22 of the needle body 12 from the blood vessel.

[0036] The material of the needle hub 14 is the first resin composition. The needle hub 14 made of the first resin composition exhibits excellent retention force with respect to the needle body 12. Therefore, when the blood collection needle 10 is withdrawn from the blood vessel, the needle body 12 moves integrally with the needle hub 14.

[0037] In the case of a used blood collection needle 10, a protector 16 is placed over the needle body 12. This prevents the needle body 12 from piercing any object. The material of the needle hub 14 is a first resin composition. The material of the protector 16 is a second resin composition. When attaching the protector 16, made of the second resin composition, to the needle hub 14, made of the first resin composition, attachment is easy. Furthermore, it is also easy to remove the protector 16 from the needle hub 14 afterward.

[0038] Furthermore, the present invention is not limited to the disclosure described above, and can take various configurations without departing from the spirit of the invention.

[0039] For example, the medical needle is not particularly limited to the blood collection needle 10. Other specific examples of medical needles include injection needles or puncture needles. [Examples]

[0040] [Example 1] A needle hub 14 was fabricated from a first resin composition in which 15 phr of TOTM was added to PVC. The proximal end 20 of the needle body 12 was supported by the needle hub 14. Meanwhile, several types of protectors 16 were individually fabricated from second resin compositions in which 45 phr, 46 phr, or 47 phr of TOTM were added to PVC, respectively. Subsequently, the protectors 16 were attached to the needle hub 14 and sterilized in an autoclaved steam sterilizer. This resulted in obtaining several types of blood collection needles 10.

[0041] Next, the protector 16 was held by the clamp of the torque measuring device. The examiner also held the needle hub 14 with one hand and the torque measuring device with the other hand. Then, rotational torque was applied to the protector 16, and the rotational torque was measured when the protector 16 separated from the needle hub 14. The rotational torque was measured for 50 blood collection needles 10, and the average value was calculated.

[0042] For comparison, a blood collection needle based on prior art was fabricated. This will be referred to as the comparative example below. The material of the needle hub in the comparative example is a resin composition in which DEHP is added to PVC. The material of the protector in the comparative example is a resin composition in which DEHP is added to PVC. In the same manner as above, the average rotational torque when the protector separated from the needle hub was calculated for 50 comparative examples.

[0043] The above results are shown in a graph in Figure 3. The vertical axis in Figure 3 represents rotational torque. The unit of rotational torque is cN·m. From Figure 3, it can be seen that the average rotational torque of the blood collection needle 10 according to this embodiment is smaller than the average rotational torque in the comparative example.

[0044] Although not specifically shown in the figures, when the needle hub 14 was made from a first resin composition to which 16 phr, 17 phr, or 18 phr of TOTM was added to PVC, results substantially similar to those in Figure 3 were obtained. In other words, with the blood collection needle 10 according to this embodiment, it is easier to separate the protector 16 from the needle hub 14 than with blood collection needles according to the prior art.

[0045] [Example 2] Multiple types of needle hubs 14 were individually prepared from a first resin composition in which 15 phr, 16 phr, 17 phr, or 18 phr of TOTM were added to PVC, respectively. The base end 20 of the needle body 12 was supported by the needle hub 14. Next, the needle hub 14 was gripped with a fixed clamp, and the needle body 12 was gripped with a movable clamp. In this state, the movable clamp was moved away from the fixed clamp, thereby applying tensile strength to the needle body 12. The tensile strength at which the needle body 12 detached from the needle hub 14 was measured. The tensile strength was measured for 100 test pieces, and the average value was calculated. Similarly, for a comparative example without a protector, the tensile strength was measured for 100 test pieces, and the average value was calculated.

[0046] The results are shown in Figure 4. Note that the unit of the vertical axis in Figure 4 is N. From Figure 4, it can be seen that the average tensile strength of the blood collection needle 10 according to this embodiment is approximately the same as the average tensile strength of the comparative example. In other words, in this embodiment as well, the needle hub 14 exhibits sufficient holding force against the needle body 12. Therefore, the needle body 12 is less likely to shift position relative to the needle hub 14.

[0047] [Example 3] Multiple types of needle hubs 14 were individually fabricated from a first resin composition in which 15 phr, 16 phr, 17 phr, or 18 phr of TOTM was added to PVC, respectively. The proximal end 20 of the needle body 12 was supported by the needle hub 14. Meanwhile, a protector 16 was fabricated from a second resin composition in which 45 phr of TOTM was added to PVC. Subsequently, the protector 16 was attached to the needle hub 14 and sterilized in an autoclave. This resulted in obtaining multiple types of blood collection needles 10.

[0048] After separating the protector 16 from the needle hub 14, the needle hub 14 was gripped with a fixed clamp, and the protector 16 was gripped with a movable clamp. Next, the movable clamp was moved toward the fixed clamp, and the protector 16 was attached to the needle hub 14. Then, the movable clamp was moved away from the fixed clamp, and the protector 16 attached to the needle hub 14 was pulled out from the needle hub 14. The force required for attachment and removal was measured. The attachment and removal force was measured for 100 blood collection needles 10, and the average value was calculated. Similarly, the average value of the attachment and removal force for 100 comparative examples was calculated.

[0049] The results are shown in Figure 5. The unit on the vertical axis in Figure 5 is Newtons (N). From Figure 5, it can be seen that the average detachment force of the blood collection needle 10 according to this embodiment is approximately the same as the average detachment force in the comparative example. Although not specifically shown, when the protector 16 was made from a second resin composition in which 46 phr or 47 phr of TOTM was added to PVC, results approximately the same as those in Figure 5 were obtained.

[0050] In other words, in this embodiment, it is easy to attach the protector 16 to the needle hub 14 and to detach the protector 16 attached to the needle hub 14 from the needle hub 14.

[0051] [Example 4] A resin composition prepared by adding 45 phr of TOTM to PVC was molded into a cylindrical shape to obtain a molded product. An annular sample piece was cut from this molded product. This will be called Sample A. Separately, a test piece identical in shape to Sample A was obtained from a resin composition prepared by adding 45 phr of DEHP to PVC. This will be called Sample B.

[0052] Small-angle X-ray scattering (SAXS) measurements were performed on samples A and B using a Bruker AXS NANOSTAR in a vacuum atmosphere. CuKα X-rays were used, with an output of 45kV / 120mA. The camera length was 104.4cm, and the exposure time was 180 minutes. Figure 6 shows the SAXS scattering curves with wavelength on the horizontal axis and intensity on the vertical axis. Furthermore, curve fitting was performed on the SAXS scattering curve of sample A. The results are shown in Figure 7.

[0053] Here, Figure 8 schematically shows an ideal crystal. In an ideal crystal, atoms are arranged regularly. Figure 9 schematically shows an amorphous material. In an amorphous material, the arrangement of atoms is irregular. From Figures 6 and 7, it can be inferred that in the structure of sample A, as shown in Figure 10A, although crystalline and amorphous regions are mixed, the disorder in the amorphous region is small, and the crystalline and amorphous regions are clearly separated. In other words, as shown in Figure 10B, the boundary between the crystalline and amorphous regions is clear in sample A.

[0054] Similarly, curve fitting was performed on the SAXS scattering curve of sample B. The results are shown in Figure 11. From Figures 6 and 11, it can be inferred that in the microstructure of sample B, as shown in Figure 12A, the disorder in the amorphous region is greater than in sample A, and the crystalline and amorphous regions are not clearly separated. That is, as shown in Figure 12B, in sample B, a transition region is formed between the crystalline and amorphous regions where crystals and amorphous materials are mixed. Therefore, the boundary between the crystalline and amorphous regions is unclear.

[0055] In the microstructure shown in Figure 10B, stress concentrates at the interface between the crystalline and amorphous regions. In contrast, in the microstructure shown in Figure 12B, stress concentration at the interface between the crystalline and amorphous regions is relatively difficult. This is thought to be the reason why it is easy to separate the protector 16 from the needle hub 14 in the embodiment described above.

[0056] [Example 5] Wide-angle X-ray scattering (WAXS) measurements were performed on sample A and sample B, respectively, under the same conditions as described above, except that the camera length was set to 4.55 cm and the exposure time to 60 minutes. The WAXS scattering curves, with wavelength on the horizontal axis and intensity on the vertical axis, are shown in Figure 13.

[0057] Peak separation analysis was performed on the WAXS scattering curve of sample A. The results are shown in Figure 14. The dashed line in Figure 14 represents the peak originating from the crystalline portion. The dashed line in Figure 14 represents the peak originating from the amorphous portion. The degree of crystallinity is calculated based on the sum of the areas of the peaks originating from the crystalline portion and the area of ​​the peaks originating from the amorphous portion, according to the following formula.

[0058]

number

[0059] The degree of crystallinity of sample A, calculated from the above formula, was 57%.

[0060] Peak separation analysis was also performed on the WAXS scattering curve of sample B. The results are shown in Figure 15. Similar to Figure 14, the dashed line indicates peaks originating from the crystalline portion, and the fine dashed line indicates peaks originating from the amorphous portion. The degree of crystallinity of sample B, calculated from the above formula, was 59%.

[0061] The degree of crystallinity of sample A is lower than that of sample B. However, as described above, a clear interface exists between the crystalline and amorphous portions in sample A. Based on this, it is presumed that in the blood collection needle 10 according to this embodiment, the protector 16 can be separated from the needle hub 14 with a small rotational torque.

Claims

1. A medical needle comprising a needle body, a hub that supports the proximal end of the needle body in the longitudinal direction, and a protector that protects the needle body, The protector has a needle covering portion that covers the portion of the needle body exposed from the hub, The needle covering portion is detachably joined to the hub, The hub is made of a first resin composition, and the needle covering portion is made of a second resin composition. The first resin composition contains polyvinyl chloride and trimellitic acid ester, and the proportion of trimellitic acid ester is 10 to 20 phr. The second resin composition contains polyvinyl chloride and trimellitic acid ester, and the proportion of trimellitic acid ester is 40 to 50 phr, for use as a medical needle.

2. A medical needle according to claim 1, wherein the proportion of trimellitic acid ester in the first resin composition is 13 to 18 phr, and the proportion of trimellitic acid ester in the second resin composition is 45 to 47 phr.

3. A medical needle according to claim 1 or 2, wherein the trimellitic acid ester is trimellitic acid tris(2-ethylhexyl).

4. A medical needle according to claim 1, wherein the protector has an outer covering portion that covers the needle covering portion.

5. A medical needle according to claim 4, wherein the material of the outer covering portion is the same second resin composition as the needle covering portion.

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