PLA composition and preparation method thereof

Abstract

The invention discloses a PLA composition and a preparation method thereof, and relates to the technical field of PLA modification. The PLA composition is prepared from the following components in parts by weight: 28 to 80 parts of PLA; 19 to 61 parts of a polyvinylpyrrolidone-vinyl acetate copolymer; 0.8 to 12 parts of polyvinyl alcohol; and the weight-average molecular weight of the polyvinylpyrrolidone-vinyl acetate copolymer is 0.5 to 200 thousand. According to the present invention, the polyvinylpyrrolidone-vinyl acetate copolymer is added to the PLA to be compounded with the polyvinyl alcohol, and the molecular weight of the polyvinylpyrrolidone-vinyl acetate copolymer is limited, such that the PLA blood affinity and the blood sample extraction efficiency can be substantially improved, the transparency of the material is maintained, and the blood sample extraction visualization is ensured.

Description

Technical Field

[0001] The present invention relates to the technical field of PLA modification, and in particular to a PLA composition and a preparation method thereof. Background Art

[0002] Polylactic acid (PLA) is a bio-based and renewable biodegradable material, made from starch raw materials from renewable plant resources. It has good biodegradability and can be completely degraded by microorganisms in nature under specific conditions after use, eventually generating carbon dioxide and water without polluting the environment. This is very beneficial to environmental protection and is a recognized environmentally friendly material. As a bio-based and renewable biodegradable material, PLA has two types: semi-crystalline and amorphous. In addition to excellent biocompatibility, good rigidity and strength, amorphous PLA also has good transparency. It has been widely used in the medical industry, especially in the emerging field of automatic blood testing. PLA materials are increasingly used due to their own biocompatibility, degradability and transparency.

[0003] However, as a polymer material, PLA has insufficient hemophilicity, that is, the blood has poor wetting ability on the material. As a result, although the visibility of the blood sample is guaranteed during the blood sampling process, the sampling speed is slow, which seriously affects the sampling efficiency and urgently needs to be improved. Summary of the invention

[0004] The purpose of the present invention is to overcome the shortcomings of the prior art and provide a PLA composition and a preparation method thereof. The present invention can greatly improve the hemophilicity of PLA and the blood sample extraction efficiency by adding polyvinyl pyrrolidone-vinyl acetate copolymer and polyvinyl alcohol to PLA and limiting the molecular weight of the polyvinyl pyrrolidone-vinyl acetate copolymer, while maintaining the transparency of the material and ensuring the visualization of blood sample extraction.

[0005] To achieve the above object, the technical solution adopted by the present invention is:

[0006] In a first aspect, the present invention provides a PLA composition comprising the following components in parts by weight:

[0007] PLA 28-80 parts; polyvinyl pyrrolidone-vinyl acetate copolymer 19-61 parts; polyvinyl alcohol 0.8-12 parts; the weight average molecular weight of the polyvinyl pyrrolidone-vinyl acetate copolymer is 0.5-200,000.

[0008] Since the pyrrolidone segment in the polyvinyl pyrrolidone-vinyl acetate copolymer has good biocompatibility and good hemophilicity, the present invention is beneficial to strengthen the affinity of PLA to blood, reduce the contact angle between blood and materials, and improve the wetting ability of blood to materials by adding polyvinyl alcohol to the polyvinyl pyrrolidone-vinyl acetate copolymer, thereby increasing the hemophilicity of the PLA material, and also making the PLA composition have excellent transparency, ensuring the visualization of blood sample extraction. If the polyvinyl pyrrolidone-vinyl acetate copolymer and polyvinyl alcohol are improperly compounded, the hemophilicity and transparency of the composition will be affected, resulting in a decrease in the efficiency of blood sample sampling.

[0009] If the molecular weight of the polyvinyl pyrrolidone-vinyl acetate copolymer is too high, the material has poor processability and low surface content, which is not conducive to improving the hemophilicity; if the molecular weight of the polyvinyl pyrrolidone-vinyl acetate copolymer is too low, although it is easy to attach to the surface, it is easy to be swollen by water-soluble substances, affecting the transparency of the composition. Therefore, the present invention controls the molecular weight of the polyvinyl pyrrolidone-vinyl acetate copolymer within the above range, which is beneficial to improving the hemophilicity of the PLA composition while ensuring that the material has a high transparency.

[0010] Preferably, the molar ratio of vinyl pyrrolidone to vinyl acetate in the polyvinyl pyrrolidone-vinyl acetate copolymer is (50-85): (15-50).

[0011] More preferably, the molar ratio of vinyl pyrrolidone to vinyl acetate in the polyvinyl pyrrolidone-vinyl acetate copolymer is (55-79): (21-45).

[0012] The present invention controls the molar ratio of vinyl pyrrolidone to vinyl acetate within the above range, which is beneficial to improving the compatibility between the polyvinyl pyrrolidone-vinyl acetate copolymer and PLA, thereby improving the transparency of the composition, thereby improving the blood sampling efficiency.

[0013] More preferably, the molar ratio of vinyl pyrrolidone to vinyl acetate in the polyvinyl pyrrolidone-vinyl acetate copolymer is (65-70): (30-35).

[0014] More preferably, the molar ratio of vinyl pyrrolidone to vinyl acetate in the polyvinyl pyrrolidone-vinyl acetate copolymer is in the range of any one or both of 79:21, 70:30, 65:35, and 55:45.

[0015] Preferably, the weight average molecular weight of the polyvinyl pyrrolidone-vinyl acetate copolymer is 20,000-100,000.

[0016] More preferably, the weight average molecular weight of the polyvinyl pyrrolidone-vinyl acetate copolymer is in the range of any one or both of 20,000, 30,000, 40,000, 50,000, 60,000, 70,000, 80,000, 90,000 and 100,000.

[0017] Preferably, the weight average molecular weight of the polyvinyl alcohol is 0.5-150,000.

[0018] The present invention controls the molecular weight of polyvinyl alcohol within the above range, which is beneficial to further improve the timeliness of the hemophilicity of the material and is also beneficial to the processing of the material.

[0019] Preferably, the refractive index of the polyvinyl alcohol is 1.48-1.50, and more preferably 1.49-1.493.

[0020] The refractive index of the polyvinyl alcohol described in the present invention is obtained by testing with an Abbe refractometer.

[0021] Preferably, the PLA is amorphous DL-PLA.

[0022] In the present invention, polyvinyl pyrrolidone-vinyl acetate and amorphous PLA composed of vinyl pyrrolidone and vinyl acetate in a specific ratio are miscible, the system itself is transparent, and its refractive index is additive, so the refractive index of polyvinyl pyrrolidone-vinyl acetate will not affect the transparency of the composition, and it is only necessary for the refractive index of polyvinyl alcohol to match the system.

[0023] Preferably, the weight average molecular weight of the PLA is 50,000-200,000, more preferably 100,000-170,000.

[0024] Preferably, the PLA composition comprises the following components in parts by weight:

[0025] PLA 30-79 parts; polyvinyl pyrrolidone-vinyl acetate copolymer 20-60 parts; polyvinyl alcohol 1-10 parts.

[0026] Preferably, in the PLA composition, the mass percentage of PLA is not less than 60%.

[0027] Preferably, the PLA composition further comprises 0-1 part of an antioxidant and 0-1 part of a lubricant.

[0028] Preferably, the antioxidant is at least one of hindered phenols, phosphites, metal alkylthiophosphoric acids, carbamic acids, and organic sulfur antioxidants.

[0029] Preferably, the lubricant is at least one of amides, polysiloxanes, stearates, PE wax and PP wax.

[0030] In a second aspect, the present invention further provides a method for preparing a PLA composition, comprising the following steps:

[0031] The components in the PLA composition are mixed uniformly, and then placed in a twin-screw extruder for melt extrusion and granulation to obtain the PLA composition.

[0032] Preferably, during melt extrusion, the temperature of each section of the twin-screw extruder is 120-210°C.

[0033] More preferably, the temperature of the twin-screw extruder is divided into ten zones, the temperature from zone 1 to zone 2 is 120-170°C, the temperature from zone 3 to zone 5 is 190-210°C, and the temperature from zone 6 to zone 10 is 170-190°C.

[0034] In a third aspect, the present invention further provides a use of a PLA composition in preparing a blood collection needle.

[0035] The PLA composition prepared by the present invention has high transparency and good biocompatibility, has good affinity to blood, and is particularly suitable for application in the field of rapid detection in the medical industry, such as in transparent blood collection needles.

[0036] Compared with the prior art, the present invention has the following beneficial effects: the present invention provides a PLA composition, which can greatly improve the hemophilicity of PLA and the blood sample extraction efficiency by adding polyvinyl pyrrolidone-vinyl acetate copolymer and compounding with polyvinyl alcohol and limiting the molecular weight of the polyvinyl pyrrolidone-vinyl acetate copolymer, while maintaining the transparency of the material to ensure the visualization of blood sample extraction. DETAILED DESCRIPTION

[0037] In order to better illustrate the purpose, technical solutions and advantages of the present invention, the present invention will be further described below in conjunction with specific embodiments, but the protection scope and implementation methods of the present invention are not limited thereto.

[0038] Unless otherwise specified, the materials and reagents used in the following examples are commercially available.

[0039] Examples 1-14

[0040] The embodiments of the PLA composition and the preparation method thereof of the present invention, the components of the PLA composition are shown in Table 1.

[0041] The preparation method of the PLA composition comprises the following steps:

[0042] The components are mixed uniformly, and then placed in a twin-screw extruder for melt extrusion at 120-210° C. and granulated to obtain the PLA composition;

[0043] The temperature of the twin-screw extruder is divided into ten zones, the temperature from zone 1 to zone 2 is 120-170°C, the temperature from zone 3 to zone 5 is 190-210°C, and the temperature from zone 6 to zone 10 is 170-190°C.

[0044] Comparative Examples 1-5

[0045] The difference between each comparative example and the embodiment is only in the type and proportion of components, as shown in Table 2.

[0046] Among the components described in each embodiment and comparative example:

[0047] The weight average molecular weight of the PLA1 is 50,000, produced by Zhuhai Wantong, model OL-50000;

[0048] The weight average molecular weight of the PLA2 is 100,000, and the product is from Zhuhai Wantong, with the model number of KB600 UN20;

[0049] The weight average molecular weight of the PLA3 is 170,000, and the product is from Zhuhai Wantong, with the model number being KB600 SF20.

[0050] The PVP-VAC-1 is a polyvinyl pyrrolidone-vinyl acetate copolymer, with a weight average molecular weight of 10,000, and is self-made; the molar ratio of vinyl pyrrolidone to vinyl acetate in the polyvinyl pyrrolidone-vinyl acetate copolymer is 55:45;

[0051] The PVP-VAC-2 is a polyvinyl pyrrolidone-vinyl acetate copolymer, with a weight average molecular weight of 5,000, and is self-made; the molar ratio of vinyl pyrrolidone to vinyl acetate in the polyvinyl pyrrolidone-vinyl acetate copolymer is 55:45;

[0052] The PVP-VAC-3 is a polyvinyl pyrrolidone-vinyl acetate copolymer, with a weight average molecular weight of 100,000, and is self-made; the molar ratio of vinyl pyrrolidone to vinyl acetate in the polyvinyl pyrrolidone-vinyl acetate copolymer is 55:45;

[0053] The PVP-VAC-4 is a polyvinyl pyrrolidone-vinyl acetate copolymer, with a weight average molecular weight of 200,000, and is self-made; the molar ratio of vinyl pyrrolidone to vinyl acetate in the polyvinyl pyrrolidone-vinyl acetate copolymer is 55:45;

[0054] The PVP-VAC-5 is a polyvinyl pyrrolidone-vinyl acetate copolymer, with a weight average molecular weight of 350,000, and is self-made; the molar ratio of vinyl pyrrolidone to vinyl acetate in the polyvinyl pyrrolidone-vinyl acetate copolymer is 55:45;

[0055] The PVP-VAC-6 is a polyvinyl pyrrolidone-vinyl acetate copolymer, the molar ratio of vinyl pyrrolidone:vinyl acetate is 50:50, and it is homemade; the weight average molecular weight of the polyvinyl pyrrolidone-vinyl acetate copolymer is 100,000;

[0056] The PVP-VAC-7 is a polyvinyl pyrrolidone-vinyl acetate copolymer, the molar ratio of vinyl pyrrolidone:vinyl acetate is 55:45, and it is homemade; the weight average molecular weight of the polyvinyl pyrrolidone-vinyl acetate copolymer is 100,000;

[0057] The PVP-VAC-8 is a polyvinyl pyrrolidone-vinyl acetate copolymer, the molar ratio of vinyl pyrrolidone:vinyl acetate is 65:35, and it is homemade; the weight average molecular weight of the polyvinyl pyrrolidone-vinyl acetate copolymer is 100,000;

[0058] The PVP-VAC-9 is a polyvinyl pyrrolidone-vinyl acetate copolymer, the molar ratio of vinyl pyrrolidone to vinyl acetate is 79:21, and it is homemade; the weight average molecular weight of the polyvinyl pyrrolidone-vinyl acetate copolymer is 100,000;

[0059] The PVP-VAC-10 is a polyvinyl pyrrolidone-vinyl acetate copolymer, the molar ratio of vinyl pyrrolidone:vinyl acetate is 85:15, and it is homemade; the weight average molecular weight of the polyvinyl pyrrolidone-vinyl acetate copolymer is 100,000.

[0060] The PVP is polyvinyl pyrrolidone, brand PVP K60;

[0061] The PC is polycarbonate, and its brand number is PC1300-22 NP.

[0062] The polyvinyl alcohol 1 is AQ-4104, with a refractive index of 1.493 and a weight average molecular weight of 50,000;

[0063] The polyvinyl alcohol 2 is of low viscosity type, with a refractive index of 1.491 and a weight average molecular weight of 5,000; the manufacturer is Kramar;

[0064] The polyvinyl alcohol 3 is PVA 088-35, with a refractive index of 1.493 and a weight-average molecular weight of 150,000; the manufacturer is Sichuan Wei.

[0065] The antioxidant is a commercially available hindered phenol antioxidant.

[0066] The lubricant is commercially available vinyl bisstearamide.

[0067] The preparation method of the polyvinyl pyrrolidone-vinyl acetate copolymer is:

[0068] Under an inert gas atmosphere, with anhydrous ethanol as solvent, weigh N-vinyl pyrrolidone monomer and vinyl acetate monomer, first add part of the vinyl pyrrolidone monomer and vinyl acetate monomer into the reactor at a molar ratio of 1:1, heat to 80°C, add azobisisobutyronitrile as an initiator to carry out polymerization reaction, add the remaining part of vinyl pyrrolidone monomer while the reaction is in progress, stop the reaction after 4 hours, purify and dry to obtain a powdery product.

[0069] The molar ratio of polyvinyl pyrrolidone-vinyl acetate is determined as follows:

[0070] First, the weight content of nitrogen is measured by elemental analysis, and then the weight content of nitrogen is divided by the molecular weight of nitrogen (14) to obtain the molar content of vinyl pyrrolidone N1. Then, the molar content of vinyl pyrrolidone N1 is multiplied by the molecular weight of vinyl pyrrolidone (111) to obtain the weight content of vinyl pyrrolidone W1. Subsequently, the weight content of vinyl acetate W2 is calculated, W2=1-W1, and W2 is divided by the molecular weight of vinyl acetate (86) to obtain the molar content of vinyl acetate N2. Then, the molar ratio of the two is calculated, that is, vinyl pyrrolidone:vinyl acetate=N1:N2.

[0071] The method for determining the weight average molecular weight of the polyvinyl pyrrolidone-vinyl acetate is: using GPC to test the molecular weight of the reaction product.

[0072] Unless otherwise specified, the components and raw materials used in the embodiments and comparative examples of the present invention are all commercially available raw materials, and the components and raw materials used in each parallel experiment are all of the same kind.

[0073] Table 1

[0074]

[0075]

[0076] Table 2

[0077] Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 PLA 53 53 53 53 53 PVP-VAC-1 40 PVP-VAC-2 PVP-VAC-3 45 0 PVP-VAC-4 PVP-VAC-5 40 PC 40 Polyvinyl alcohol 0 45 5 5 5 Antioxidants 1 1 1 1 1 Lubricants 1 1 1 1 1

[0078] In order to verify the performance of the PLA composition of the present invention, the products prepared in each embodiment and comparative example were subjected to the following performance tests, and the specific steps are as follows:

[0079] 1. Light transmittance: 2.0 mm square plate, tested with light transmittance-haze tester according to GB2140-1980.

[0080] 2. Hemotropism test: Test the time required to fill a specific volume blood collection tube (10ul) with blood, and evaluate the hemotropism of the material by the time.

[0081] The above experimental results are shown in Table 3.

[0082] Table 3

[0083]

[0084]

[0085] According to the comparison of Comparative Examples 1-3 in Table 3 with Example 2, it can be seen that no polyvinyl alcohol is added in Comparative Example 1, and no PVP-VAC is added in Comparative Example 2, and the hemophilicity and transparency of the PLA composition are affected. In Example 2, the addition of polyvinyl alcohol and PVP-VAC not only helps to improve the affinity of PLA for blood, but also improves the transparency of the PLA composition. In Comparative Example 3, PC is used to replace polyvinyl alcohol, and the transparency of the PLA composition is not as good as that of Example 2, indicating that only by using PVP-VAC and polyvinyl alcohol to compound, the hemophilicity of the PLA composition can be improved while ensuring that the PLA composition has a high transparency.

[0086] Comparative Examples 4-5 are compared with Example 2, respectively, and it can be seen that if the molecular weight of PVP-VAC is too small or too large, the hemophilicity and transparency of the PLA composition will be affected. The present invention controls the molecular weight of PVP-VAC to 0.5-200,000, which is not only beneficial to improving the hemophilicity of the PLA composition, but also ensures that the material has a high transparency.

[0087] According to the comparison between Examples 4-8 and Example 2, it can be found that as the molar ratio of vinyl pyrrolidone to vinyl acetate in the polyvinyl pyrrolidone-vinyl acetate copolymer gradually increases, the transparency of the PLA composition first increases and then decreases, indicating that the molar ratio of vinyl pyrrolidone to vinyl acetate controlled by the present invention is (55-79): (21-45), and the transparency of the PLA composition is optimal.

[0088] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the essence and scope of the technical solution of the present invention.

Claims

1. A PLA composition, characterized in that: The composition comprises the following components in parts by weight: PLA 28-80 parts; polyvinyl pyrrolidone-vinyl acetate copolymer 19-61 parts; polyvinyl alcohol 0.8-12 parts; the weight average molecular weight of the polyvinyl pyrrolidone-vinyl acetate copolymer is 0.5-200,000.

2. The PLA composition according to claim 1, wherein The molar ratio of vinyl pyrrolidone to vinyl acetate in the polyvinyl pyrrolidone-vinyl acetate copolymer is (50-85): (15-50).

3. The PLA composition according to claim 1, characterized in that The weight average molecular weight of the polyvinyl pyrrolidone-vinyl acetate copolymer is 20,000-100,000.

4. The PLA composition according to claim 1, wherein The weight average molecular weight of the polyvinyl alcohol is 0.5-150,000.

5. The PLA composition according to claim 1, wherein The refractive index of the polyvinyl alcohol is 1.48-1.

50.

6. The PLA composition according to claim 1, wherein The weight average molecular weight of the PLA is 50,000-200,000.

7. The PLA composition according to claim 1, characterized in that The PLA composition further comprises 0-1 part of an antioxidant and 0-1 part of a lubricant.

8. The PLA composition according to claim 7, characterized in that At least one of the following (a) to (b): (a) the antioxidant is at least one of hindered phenols, phosphites, metal alkylthiophosphoric acids, carbamic acids, and organic sulfur antioxidants; (b) The lubricant is at least one of amides, polysiloxanes, stearates, PE wax, and PP wax.

9. The method for preparing a PLA composition according to any one of claims 1 to 8, characterized in that: The following steps are involved: The components in the PLA composition are mixed uniformly, and then placed in a twin-screw extruder for melt extrusion and granulation to obtain the PLA composition.

10. Use of the PLA composition according to any one of claims 1 to 8 in preparing a blood collection needle.

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