A brittle polystyrene composite material, its preparation method and application

Abstract

The present invention relates to an easily breakable polystyrene composite material and its preparation and application. The components include: polystyrene, styrene-butadiene copolymer, and styrene-acrylonitrile copolymer. The sampling rod made of the composite material of the present invention can be broken after only one fold or bending to a certain angle after the sampling is completed. Moreover, the bending breaking force is moderate, showing good breakability, moderate flexibility, effectively improving the sampling efficiency, suitable for large-scale and multi-quantity sampling and detection, and having good application prospects in the COVID-19 nucleic acid testing industry.

Description

Technical Field

[0001] The invention belongs to the field of plastic processing, and particularly relates to an easy-to-break polystyrene composite material and a preparation method and application thereof. Background Art

[0002] Since the global outbreak of the epidemic in early 2020, nucleic acid testing has been one of the important means of diagnosing the virus. The disposable sampling rod used in nucleic acid testing needs to be broken after sampling, and the broken sampling head is placed in the sampling tube for storage before nucleic acid testing is performed later. However, the sampling rod material is generally made of high-impact polystyrene or ABS material. Due to its high strength and good toughness, it is not easy to break. After sampling, the samplers often need to use a lot of force to fold the sampling rod back and forth several times before breaking it, which seriously affects the sampling efficiency and may cause the lysis solution to spill and leak, causing pollution to the testers. On the other hand, the sampling rod cannot be too easy to break or the breaking bending force is too small, because such a sampling rod is too brittle and may cause it to break during use. Summary of the invention

[0003] In view of the defects of the prior art, the technical problem to be solved by the present invention is to provide an easy-to-break polystyrene composite material and its preparation and application.

[0004] The polystyrene composite material of the present invention comprises the following components by weight:

[0005] Polystyrene 100 parts;

[0006] 20-30 parts of styrene-butadiene copolymer;

[0007] 4-10 parts of styrene-acrylonitrile copolymer;

[0008] The content of styrene SM structural component in the styrene-butadiene copolymer is ≤41wt%;

[0009] The weight parts of the styrene-butadiene copolymer are 20 to 30 parts. If the parts are too few, the flexural strength is too high and the flexural breaking force is large; if the parts are too many, the flexural strength is too low, the composite is too soft, and it will become easy to break. In the present invention, a styrene-butadiene copolymer with a low SM content (the content of the SM structural component in the styrene-butadiene copolymer is ≤41 wt%) is selected. It has good compatibility with polystyrene and poor compatibility with styrene-butadiene. The styrene-butadiene copolymer with a low SM content will preferentially distribute in the polystyrene phase, improving the toughness of the polystyrene phase to a certain extent and effectively reducing the flexural strength of the composite. However, due to the high content of the butadiene rubber component in the styrene-butadiene copolymer with a low SM content, if too much is added, the material will become too soft and easy to break; if a styrene-butadiene copolymer with a high SM content is selected, it not only has good compatibility with the styrene-acrylonitrile copolymer but also is compatible with polystyrene and has the function of a compatibilizer, then the composite material thereof cannot achieve the effect of being easy to break.

[0010] Among them, the content of the styrene SM structural component in the styrene-acrylonitrile copolymer is ≤76 wt%.

[0011] The weight parts of the styrene-acrylonitrile copolymer are 4 to 10 parts. If the parts are too few, the flexural deflection is too high and it is not easy to break; if the parts are too many, the flexural deflection is too low and it is too easy to break. Compared with the styrene-acrylonitrile copolymer with a high SM content (SM content greater than 76 wt%), the styrene-acrylonitrile copolymer with a low SM content (SM content ≤76 wt%) has low compatibility with polystyrene. In the present invention, by selecting a styrene-acrylonitrile copolymer with a low SM content (SM structural component content is ≤76 wt%), its compatibility with the polystyrene phase can be effectively reduced, the flexural deflection of the composite can be effectively reduced, and the easy-breaking performance can be improved; while for the styrene-acrylonitrile copolymer with a high SM content (SM content greater than 76 wt%), it has a certain compatibility with polystyrene, and the composite thereof cannot achieve the effect of being easy to break.

[0012] Preferably, in the styrene-butadiene copolymer, the content of the styrene SM structural component is 35 - 40 wt%. When the content of the styrene SM structural component in the styrene-butadiene copolymer is 35 - 40 wt%, it helps to toughen polystyrene and promote the phase separation of polystyrene and the styrene-acrylonitrile copolymer.

[0013] Infrared quantitative analysis method: First, infrared analysis is performed on the mixtures of polystyrene and polybutadiene with known different ratios to establish a standard curve for measuring the content of the styrene / butadiene components. Then, according to the Lambert-Beer formula, referring to the height of the characteristic peak of styrene (1602 cm -1 ) and the height of the characteristic peak of butadiene (910 cm -1) ratio, the proportional method is used to calculate the content of the styrene SM structural component in the styrene-butadiene copolymer.

[0014] Preferably, in the styrene-acrylonitrile copolymer, as determined by infrared quantitative analysis, the content of the styrene SM structural component is 70-75 wt%. When the content of the styrene SM structural component in the styrene-acrylonitrile copolymer is 70-75 wt%, it has partial compatibility with polystyrene and styrene-butadiene copolymer. Too high or too low content will lead to too good or too poor compatibility, resulting in the composite being unable to be bent and broken or being too easily broken.

[0015] Infrared quantitative analysis method: First, establish a standard curve for the determination of acrylonitrile component content in a styrene-acrylonitrile copolymer with a known acrylonitrile monomer content (determined by the Kjeldahl method), and then, according to the Lambert-Beer formula, refer to the ratio of the acrylonitrile characteristic peak height (2237 cm -1 ) to the styrene characteristic peak height (700 cm -1 ) ratio, the proportional method is used to calculate the content of the styrene SM structural component in the styrene-acrylonitrile copolymer.

[0016] The polystyrene has a melt index of 2.5-10 g / 10 min at 200 °C and 5 kg according to the ASTM D1238-2010 standard.

[0017] Preferably, by weight, the components include:

[0018] Polystyrene 100 parts;

[0019] Styrene-butadiene copolymer 22-28 parts;

[0020] Styrene-acrylonitrile copolymer 5-8 parts.

[0021] A preparation method of the polystyrene composite material of the present invention includes:

[0022] Weigh the components according to the ratio, dry mix in a mixer for 3-5 minutes, and then melt extrude and pelletize in a twin-screw extruder to obtain the polystyrene composite material.

[0023] An application of the polystyrene composite material of the present invention in a disposable sampling rod, such as a sampling rod in pneumonia nucleic acid detection.

[0024] The present invention selects a styrene-butadiene copolymer with a low SM content (the content of the SM structural component in the styrene-butadiene copolymer is ≤ 41 wt%), which preferentially distributes in the polystyrene phase, improving the toughness of the polystyrene phase to a certain extent and effectively reducing the flexural strength of the composite. However, if too much is added, the material becomes too soft and is prone to breakage. By selecting a styrene-acrylonitrile copolymer with a low SM content (the content of the SM structural component is ≤ 76 wt%), its compatibility with the polystyrene phase is effectively reduced, which can effectively reduce the flexural deflection of the composite and improve the breakage performance. Through the selection of polystyrene, a styrene-butadiene copolymer with a specific SM content, and a styrene-acrylonitrile copolymer with a specific SM content, which have partial compatibility, and the compounding of the three base materials, a composite material with partial compatibility characteristics is obtained, achieving a balance between flexural strength and flexural deflection. When made into a sampling rod, this material has the characteristics of easy breakage and moderate flexibility, effectively improving the nucleic acid sampling efficiency over a large range.

[0025] Beneficial effects

[0026] The sampling rod made of the polystyrene composite material of the present invention can be broken after only one fold or bending to a certain angle after sampling, and the bending breaking force is moderate, showing good breakage performance, effectively improving the sampling efficiency, suitable for large-scale and multi-quantity sampling and detection, and having good application prospects in the nucleic acid detection industry. Specific embodiments

[0027] The present invention will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and not to limit the scope of the present invention. In addition, it should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms also fall within the scope defined by the appended claims of this application.

[0028] I. Source of raw materials

[0029] Polystyrene - 1PS GP550N, from Formosa Chemicals & Fibre Corporation, Taiwan, China, with a melt index of 2.5 g / 10 min at 200 °C and 5 kg according to ASTM D1238 - 2010 standard;

[0030] Polystyrene - 2PS GP5000, from Formosa Chemicals & Fibre Corporation, Taiwan, China, with a melt index of 10 g / 10 min at 200 °C and 5 kg according to ASTM D1238 - 2010 standard;

[0031] Styrene-butadiene copolymer - 1SBS3537, from Formosa Plastics Corporation, Taiwan, China, and according to infrared quantitative analysis method, the content of its SM structure (styrene structure) component is 35 wt.%;

[0032] Styrene-butadiene copolymer - 2 SBS3542, Formosa Plastics, Taiwan, China. According to infrared quantitative analysis, the content of the SM structure (styrene structure) component is 40 wt.%.

[0033] Styrene-butadiene copolymer - 3: SBS3536, Formosa Plastics, Taiwan, China. According to infrared quantitative analysis, the content of the SM structure (styrene structure) component is 30 wt.%.

[0034] Styrene-butadiene copolymer - 4 SBS3545, Formosa Plastics, Taiwan, China. According to infrared quantitative analysis, the content of the SM structure (styrene structure) component is 45 wt.%.

[0035] Styrene-acrylonitrile copolymer - 1 SAN 350, Kumho, Korea. According to infrared quantitative analysis, the content of the SM structure (styrene structure) component is 70 wt.%.

[0036] Styrene-acrylonitrile copolymer - 2 SAN NF2200, Formosa Chemicals & Fibre, Taiwan, China. According to infrared quantitative analysis, the content of the SM structure (styrene structure) component is 75 wt.%.

[0037] Styrene-acrylonitrile copolymer - 3: SAN NX3400, Formosa Chemicals & Fibre, Taiwan, China. According to infrared quantitative analysis, the content of the SM structure (styrene structure) component is 65 wt.%.

[0038] Styrene-acrylonitrile copolymer - 4 SAN 310TR, Kumho, Korea. According to infrared quantitative analysis, the content of the SM structure (styrene structure) component is 80 wt.%.

[0039] II. Preparation methods of examples and comparative examples

[0040] Weigh the raw materials by weight parts, then put them into a mixer with a rotation speed of about 100 revolutions per minute for dry mixing for 3 - 5 minutes. Then, melt and extrude the mixed raw materials into pellets using a twin-screw extruder with a length-diameter ratio of 40:1, a temperature range of 160°C, 190°C, 190°C, 200°C, 210°C, 210°C, 210°C, 220°C, 220°C, 220°C, 220°C, and a rotation speed of 450 revolutions per minute to obtain the polystyrene composite material.

[0041] III. Test standards and methods

[0042] The flexural strength is measured according to the standard of GB / T9341 - 2008, test conditions: 2 mm / min, normal temperature;

[0043] The flexural deflection is measured according to the standard of GB / T9341 - 2008, test conditions: 2 mm / min, normal temperature;

[0044] Breaking force evaluation: when the flexural strength < 30 MPa, the breaking force is too small; when 30 MPa ≤ flexural strength ≤ 40 MPa, the breaking force is moderate; when 40 MPa < flexural strength, the breaking force is too large.

[0045] Breaking performance evaluation: when the flexural deflection < 10 mm, the flexibility is poor; when 10 mm ≤ flexural deflection ≤ 30 mm, the flexibility is moderate; when 30 mm < flexural deflection < 35 mm, the flexibility is too good; when it does not break after bending, uniformly take 35 mm.

[0046] Table 1 Formulations (parts by weight) and properties of Examples 1 - 10

[0047]

[0048]

[0049] Table 2 Formulations (parts by weight) and properties of Comparative Examples 1 - 6

[0050]

[0051] From the above test results, it can be seen that a special material for disposable sampling rods provided by the present invention has a flexural deflection between 10 mm and 30 mm and a flexural strength between 30 MPa and 40 MPa, with the characteristics of moderate bending breaking force and moderate flexibility for easy breaking. For the disposable sampling rod made of this material, after the sampling is completed, it can be broken only by folding once or bending to a certain angle, effectively improving the sampling efficiency.

[0052] Comparative Example 1 uses a styrene - butadiene copolymer with a high SM content. Compared with the styrene - butadiene copolymer with a low SM content, it can improve the compatibility between polystyrene and styrene - acrylonitrile copolymer, resulting in the composite being not easy to break.

[0053] Comparative Example 2 uses a styrene - acrylonitrile copolymer with a high SM content. Compared with the styrene - acrylonitrile copolymer with a low SM content, it has a certain compatibility with polystyrene, resulting in the composite also being not easy to break.

[0054] In Comparative Example 3, the amount of styrene - butadiene copolymer used is too small, the flexural strength of the composite is too high, and the bending breaking force is too large, especially for short sampling rods, which affects the actual use and reduces the comfort of use.

[0055] In Comparative Example 4, the amount of styrene - butadiene copolymer used is too large, the flexural strength of the composite is too low, the sampling rod is too soft and too easy to break, with poor flexibility and not suitable for actual use.

[0056] In Comparative Example 5, the amount of styrene - acrylonitrile copolymer used is too small, the flexural deflection of the composite is too large, and it is not easy to break.

[0057] In Comparative Example 6, the amount of styrene-acrylonitrile copolymer used was excessive, resulting in serious phase separation of the composite, too low flexural strength and flexural deflection, poor flexibility of the composite, and being too easy to break, which was not suitable for practical use.

Claims

1. A polystyrene composite material, by weight parts, the components include: 100 parts of polystyrene; 20 - 30 parts of styrene-butadiene copolymer; 4 - 10 parts of styrene-acrylonitrile copolymer; wherein the content of styrene SM structural component in the styrene-butadiene copolymer is ≤41 wt%; the content of styrene SM structural component in the styrene-acrylonitrile copolymer is ≤76 wt%.

2. The composite material according to claim 1, characterized in that the melt index of the polystyrene under the conditions of 200 °C and 5 kg is 2.5 - 10 g / 10 min.

3. The composite material according to claim 1, characterized in that the content of styrene SM structural component in the styrene-butadiene copolymer is 35 - 40 wt%.

4. The composite material according to claim 1, characterized in that the content of styrene SM structural component in the styrene-acrylonitrile copolymer is 70 - 75 wt%.

5. The composite material according to claim 1, characterized in that by weight parts, the components include: 100 parts of polystyrene; 22 - 28 parts of styrene-butadiene copolymer; 5 - 8 parts of styrene-acrylonitrile copolymer.

6. A preparation method of the polystyrene composite material according to claim 1, including: Weigh the components according to the ratio, dry mix in a mixer for 3 - 5 minutes, and then melt extrude and pelletize in a twin-screw extruder to obtain the polystyrene composite material.

7. An application of the polystyrene composite material according to claim 1 in a disposable sampling rod.

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