A high-efficiency antibacterial and mildew-proof polypropylene masterbatch and its preparation method

Abstract

The present application provides a high-efficiency antibacterial and mildew-proof polypropylene masterbatch and a preparation method thereof. The masterbatch comprises a PP resin, an antibacterial and mildew-proof agent, and other additives. The antibacterial and mildew-proof agent is a C / ZnO composite prepared by an electrospinning method. The C / ZnO composite prepared by the electrospinning method retains the fiber form of the spinning product after carbonization. These fibrous substances can be inserted into the polypropylene molecular chain, thereby strengthening the bonding strength with the polymer and improving the dispersion of the material. The particle size range can still be maintained in the nanometer range during the dispersion process. A small amount of the masterbatch can make the PP resin have excellent antibacterial and mildew-proof effects. The masterbatch has the advantages of low improvement cost and easy promotion and implementation.

Description

Technical Field

[0001] The invention belongs to the field of plastic masterbatches, and particularly relates to a high-efficiency antibacterial and mildew-proof polypropylene masterbatch and a preparation method thereof. Background Art

[0002] Polypropylene, due to its excellent performance and compliance with relevant food safety regulations, is ubiquitous in our daily lives. However, during use, polypropylene products are susceptible to bacterial attack and contamination, which can lead to mold and contamination of the product contents, which is detrimental to user health. This is especially true in southern China, where the rainy season provides favorable conditions for bacterial and mold growth. Existing solutions typically involve adding antibacterial and mildew-proofing agents to resins. Zinc oxide, a popular choice due to its abundant availability and low price, is currently a major concern. However, two issues hinder its application in mold and mildew prevention: 1. Common commercially available zinc oxide has a wide particle size distribution, ranging from a few nanometers to hundreds of microns. Larger zinc oxide particles are ineffective when added to resins and fail to achieve the desired antibacterial and mildew-proofing effects. 2. Nano-zinc oxide is poorly dispersed in resins, failing to achieve the desired antibacterial and mildew-proofing effects. Due to its small particle size and large specific surface area, nano-zinc oxide easily agglomerates during processing, reducing its effective usage and failing to achieve its desired effect. Improvements are urgently needed. Summary of the Invention

[0003] The first purpose of the present invention is to solve the technical problems that existing polypropylene products are easily contaminated by bacteria, have poor antibacterial and mildew-proof effects, and have poor dispersion effects of the existing antibacterial agent nano zinc oxide in resin, and to propose a highly effective antibacterial and mildew-proof polypropylene masterbatch;

[0004] Another object of the present invention is to provide a method for preparing a highly effective antibacterial and mildew-proof polypropylene masterbatch.

[0005] In order to achieve the first purpose, this application adopts the following scheme:

[0006] A highly effective antibacterial and mildew-proof polypropylene masterbatch, composed of the following components in parts by weight:

[0007]

[0008] The antibacterial and mildew-proof agent is a C / ZnO complex prepared by an electrostatic spinning method.

[0009] In the actual implementation process, the C / ZnO composite prepared by electrospinning has a uniform fiber diameter distribution and a nanometer-level diameter compared with ordinary zinc oxide particles. It is easy to disperse in PP resin and has a large specific surface area. Under light, it can automatically decompose negatively charged electrons in water and air, leaving positively charged vacancies. These vacancies can stimulate oxygen in the air to become active oxygen, which oxidizes bacteria to kill bacteria and prevent bacterial reproduction. Compared with nano zinc oxide powder, the C / ZnO composite has a fibrous structure. During the mixing and dispersion process, it can be connected to the molecular chain of PP resin, making it more strongly bound to the polymer, thereby improving its dispersion.

[0010] Preferably, the preparation method of the antibacterial and mildew-proof agent comprises the following steps:

[0011] Step 101. Add the polymer carrier and the zinc salt in a weight ratio of 1:1-1.5 into a solvent, stir magnetically at 500-1000 rpm at room temperature for 5-10 minutes, and then ultrasonically disperse for 5-10 minutes to obtain a spinning solution.

[0012] Step 102: transferring the spinning solution obtained in step 101 into a syringe for electrospinning to obtain antibacterial and mildew-proof masterbatch;

[0013] Step 103: Spinning the antibacterial and mildew-proof masterbatch obtained in step 102 in a special gas environment at 500-1200° C. for 3 hours to obtain an antibacterial and mildew-proof agent;

[0014] Preferably, in step 101, the polymer carrier is one or a mixture of more than one of polyacrylonitrile, polyvinyl pyrrolidone, and polyvinylidene fluoride.

[0015] More preferably, in step 101, the polymer carrier is polyacrylonitrile.

[0016] In the actual implementation process, polyacrylonitrile is selected, which has the following advantages:

[0017] First, polyacrylonitrile has high thermal stability and can be spun at relatively high temperatures, which makes it suitable for electrospinning processes that require higher spinning temperatures.

[0018] Secondly, it has good solubility, which allows polyacrylonitrile to be easily prepared into a solution with moderate solubility in a variety of solvents for electrospinning, with little solvent restriction;

[0019] Third, because polyacrylonitrile has high chain strength and molecular weight, its fibers can form relatively high tensile strength during the electrospinning process, which makes the fibers prepared from polyacrylonitrile have good mechanical properties and strength, is conducive to spinning uniformly, and easily forms a "Taylor pile".

[0020] Preferably, in step 101, the zinc salt is one or a mixture of more than one of zinc acetate, zinc nitrate and zinc sulfate.

[0021] More preferably, in step 101, the zinc salt is zinc acetate.

[0022] In the actual implementation process, the selection of zinc acetate can meet the antibacterial and mildew-proof requirements of the product, and has the following advantages:

[0023] First, zinc acetate has good electrical conductivity and can effectively conduct electricity. In electrospinning, electrical conductivity is the key to generating an electrostatic field, which can help fiber formation. When combined with polyacrylonitrile, it can produce nano-scale, high-strength fibers.

[0024] Secondly, zinc acetate has good solubility and can form a stable solution in an appropriate solvent. This allows zinc acetate to be easily mixed with other solvents and polymers to prepare a suitable electrospinning solution. When combined with polyacrylonitrile, it can stably produce fibers with high tensile strength.

[0025] Third, the concentration range of zinc acetate used in electrospinning is relatively wide and can be adjusted as needed. A lower concentration can make the charge density on the fiber surface moderate, which is conducive to the formation of filaments, while a higher concentration can increase the speed and stability of filament formation.

[0026] Fourthly, zinc acetate can reduce the surface tension of the fiber during the electrospinning process, so that the fiber maintains good morphological stability during the flight process, which helps the uniform stretching and formation of the fiber, reduces the breakage and deformation of the fiber, and is conducive to the stable formation of fibers with a diameter of nanometer level;

[0027] Fifth, zinc acetate makes the spinning process have good controllability and consistency. It can be controlled by adjusting parameters such as concentration and spinning distance to obtain the desired fiber properties and characteristics. Under stable process conditions, the use of zinc acetate can obtain more consistent fiber quality and performance. In the subsequent masterbatch preparation process, zinc acetate is evenly dispersed and has a large contact area with the outside world, which can effectively improve the antibacterial and anti-mildew effect of PP masterbatch.

[0028] Preferably, in step 101, the solvent is one or a mixture of more than one of DMF, DMAc, and THF.

[0029] More preferably, in step 101, the solvent is DMF.

[0030] In the actual implementation process, the use of DMF as a solvent has the following advantages:

[0031] First, DMF has high solubility and can dissolve a variety of polymers, such as polyacrylonitrile, so that DMF can be used to prepare high-concentration spinning solutions, which is conducive to continuous spinning of fibers, facilitates large-scale production, and meets the demand for PP masterbatch;

[0032] Secondly, DMF has good volatility and can evaporate quickly after electrospinning, leaving behind the spun fibers. This helps the fibers to solidify and form quickly, preventing them from twisting or deforming during the spinning process, and is beneficial to improving the stability and production efficiency of fiber spinning.

[0033] Third, the low surface tension of DMF facilitates fiber formation and stretching, allowing the fibers to maintain good morphological stability during the spinning process. This can promote uniform stretching and formation of the fibers and reduce fiber breakage and deformation.

[0034] Preferably, in step 102, the diameter of the syringe needle is 0.1-0.5 mm, the electrospinning voltage is 30-40 KV, and the distance between the syringe needle tip and the receiving spinning copper plate is 20-30 cm.

[0035] Preferably, the protective gas in step 103 is a mixture of N2 and O2 in a volume ratio of 8-10:1.

[0036] Preferably, the filler is one or a mixture of more than one of calcium carbonate, talc, cellulose, and fumed silica.

[0037] To achieve the second purpose of this application, this application adopts the following scheme:

[0038] A method for preparing a high-efficiency antibacterial and mildew-proof polypropylene masterbatch comprises the following steps:

[0039] Step 201. Place the PP resin, antibacterial and mildew-proof agent, filler, and other additives into a high-speed disperser in the order in which they are placed, and stir at room temperature and 250-800 rpm for 10-20 minutes to obtain a premix.

[0040] Step 202. The premix obtained in step 201 is fed into a twin-screw extruder, and after passing through the twin-screw feeding section, conveying section, mixing section, negative pressure section and extrusion section, it is cooled and pelletized to obtain a high-efficiency antibacterial and mildew-proof polypropylene masterbatch.

[0041] Compared with the prior art, the present invention has the following advantages:

[0042] 1. The present application provides a high-efficiency antibacterial and mildew-proof polypropylene masterbatch, which is composed of PP resin, antibacterial and mildew-proof agents and other additives, wherein the antibacterial and mildew-proof agent is a C / ZnO composite prepared by an electrospinning method. The C / ZnO composite prepared by the electrospinning method retains the fiber form of the spinning after carbonization. These fibrous substances can be inserted into the polypropylene molecular chain, making it more strongly bonded to the polymer and having better dispersion of the material. The nanometer-scale particle size range can still be maintained during the dispersion process, which increases the probability of reaction with bacteria, thereby greatly improving the mildew and antibacterial efficiency. A small amount of use can make the PP resin have excellent antibacterial and mildew-proof effects, which has the advantages of low improvement cost and easy promotion and implementation.

[0043] 2. The present application provides a method for preparing a highly effective antibacterial and mildew-proof polypropylene masterbatch, which is simple, quick, easy to promote, and has wide applicability. The preparation can be advanced or delayed according to different construction requirements to meet different construction needs. DETAILED DESCRIPTION

[0044] The present invention will be further described below with reference to specific examples 1-2 and comparative examples 1-3:

[0045] Example 1.

[0046] (1) Preparation of antibacterial and mildew-proof agent according to the weight parts shown in Table 1:

[0047] Step 101. Polyacrylonitrile and zinc acetate are added to an organic solvent, DMF, in a weight ratio of 1:1. The mixture is magnetically stirred at 500 rpm for 8 minutes at room temperature. After stirring, the mixture is ultrasonically dispersed for 6 minutes to obtain a spinning solution.

[0048] Step 102. Transfer the spinning solution obtained in step 101 into a syringe with a needle diameter of 0.2 mm, and perform electrospinning at an operating voltage of 35 kV and a distance of 20 cm between the syringe needle tip and the receiving spinning copper plate to obtain an antibacterial and mildew-proof masterbatch.

[0049] Step 103. The antibacterial and mildew-proof spinning obtained in step 102 is carbonized for 3 hours at 700°C in a protective gas environment to obtain an antibacterial and mildew-proof agent; wherein the protective gas is a mixture of N2 and O2 in a volume ratio of 8:1.

[0050] (2) Preparation of high-efficiency antibacterial and mildew-proof polypropylene masterbatch according to the weight parts shown in Table 1:

[0051] Step 201. PP resin, antibacterial and mildew-proof agent, filler, and other additives are sequentially placed into a high-speed disperser and stirred at room temperature and 260 rpm for 12 minutes to obtain a premix;

[0052] Step 202. The premix obtained in step 201 is put into a twin-screw extruder, and after passing through the twin-screw feeding section, conveying section, mixing section, negative pressure section and extrusion section, it is cooled and pelletized to obtain high-efficiency antibacterial and mildew-proof polypropylene masterbatch, wherein the temperature of the feeding section is 190°C, the temperature of the conveying section is 195°C, the temperature of the mixing section is 200°C, the temperature of the negative pressure section is 210°C, the temperature of the extrusion section is 205°C, and the temperature of the twin-screw extruder head is 200°C.

[0053] Example 2.

[0054] (1) Preparation of antibacterial and mildew-proof agent according to the weight parts shown in Table 1:

[0055] Step 101. Polyacrylonitrile and zinc acetate are added to an organic solvent, DMF, in a weight ratio of 1:1.2. The mixture is magnetically stirred at 700 rpm for 5 minutes at room temperature. After stirring, the mixture is ultrasonically dispersed for 6 minutes to obtain a spinning solution.

[0056] Step 102. The spinning solution obtained in step 101 is transferred into a syringe with a diameter of 0.5 mm, and electrospinning is performed under the conditions of an electrospinning voltage of 35 kV and a distance of 25 cm between the syringe needle tip and the receiving spinning copper plate to obtain an antibacterial and mildew-proof masterbatch;

[0057] Step 103. Carbonize the antibacterial and mildew-proof spinning obtained in step 102 at 750° C. for 3 hours in a protective gas environment to obtain an antibacterial and mildew-proof agent; wherein the protective gas is a mixture of N2 and O2 in a volume ratio of 9:1.

[0058] (2) Preparation of high-efficiency antibacterial and mildew-proof polypropylene masterbatch according to the weight parts shown in Table 1:

[0059] Step 201. PP resin, antibacterial and mildew-proof agent, filler, and other additives are sequentially placed into a high-speed disperser and stirred at room temperature and 500 rpm for 15 minutes to obtain a premix;

[0060] Step 202. The premix obtained in step 201 is put into a twin-screw extruder, and after passing through the twin-screw feeding section, conveying section, mixing section, negative pressure section and extrusion section, it is cooled and pelletized to obtain high-efficiency antibacterial and mildew-proof polypropylene masterbatch. In step 202, the temperature of the feeding section is 192°C, the temperature of the conveying section is 198°C, the temperature of the mixing section is 212°C, the temperature of the negative pressure section is 213°C, the temperature of the extrusion section is 206°C, and the temperature of the twin-screw extruder head is 202°C.

[0061] Comparative Example 1.

[0062] The antibacterial and mildew-proof agent in Example 2 was replaced with an equal amount of commercially available zinc oxide powder with a particle size of 0.2 μm, while the other components remained unchanged, to prepare a masterbatch.

[0063] Comparative Example 2.

[0064] The antibacterial and mildew-proofing agent in Example 1 was replaced with an equal amount of filler, while the other components remained unchanged, to prepare a masterbatch.

[0065] Comparative Example 3.

[0066] The antibacterial and mildew-proofing agent in Example 2 was replaced with an equal amount of filler, while the other components remained unchanged, to prepare a masterbatch.

[0067] Table 1 Components of a high-efficiency antibacterial and mildew-proof polypropylene masterbatch according to weight parts in Examples 1-2 and Comparative Examples 1-3:

[0068]

[0069] The PP masterbatches prepared in Examples 1-2 and Comparative Examples 1-3 were subjected to the following tests. The PP resin selected in Example 1 was CNOOC Shell homopolymer PP HP500N (MFR=14 g / 10 min). A PP masterbatch with an antibacterial and mildew-proofing agent content of 5% was prepared according to the weight parts in Example 1 in Table 1. The masterbatch prepared in Example 1 and homopolymer PP HP500N (i.e., the pure PP masterbatch in Example 1) were proportioned according to Table 2 below. The masterbatch with an antibacterial and mildew-proofing agent content of 0% prepared in Comparative Example 2 was proportioned according to Table 2 below. Test plates No. 1, No. 2, No. 3, No. 4, No. 5, and No. 6 with a size of 5*5*0.1 cm were prepared using an injection molding machine.

[0070] The PP resin selected in Example 2 is Maoming Petrochemical copolymer PP HT9025NX (MFR=25g / 10min), and the PP masterbatch with an antibacterial and mildew-proofing agent content of 15% is prepared according to the weight parts in Example 2 in Table 1. The masterbatch prepared in Example 2 and the copolymer PP HT9025NX (i.e., the pure PP masterbatch in Example 2) are proportioned according to Table 3 below. The masterbatch with a zinc oxide powder content of 15% prepared in Comparative Example 1 is proportioned according to Table 3 below, and the masterbatch with an antibacterial and mildew-proofing agent content of 0% prepared in Comparative Example 3 is proportioned according to Table 3 below. Test plates No. 7, No. 8, No. 9, No. 10, No. 11, No. 12, and No. 13 with a size of 5*5*0.1cm are prepared using an injection molding machine.

[0071] The prepared No. 1-13 were tested according to the standards ISO 846, GB / T 31402, GB / T1843, GB / T1040 and GB / T 31402-2015. The test results are summarized in Tables 2, 3 and 4.

[0072] Table 21-6 Test plate ratio and test results

[0073]

[0074] Table 37-13 Test plate ratio and test results

[0075]

[0076]

[0077] Table 4 Antibacterial test results of test plates No. 5, No. 6, No. 11, No. 12 and No. 13

[0078]

[0079] As shown in the test results in Table 4, test plates No. 5 and No. 11 are test plates with an antibacterial and mildew-proofing agent content of 1%, and test plate No. 13 is a test plate with a commercially available nano-zinc oxide content of 1%. After adding the antibacterial and mildew-proofing agent, the antibacterial and mildew-proofing properties of the PP masterbatch are significantly enhanced, reaching a maximum of >99.9%. For test plate No. 13, since the nano-zinc oxide has a low degree of dispersion in PP and a poor mixing effect, the subsequent preparation of the antibacterial and mildew-proof PP masterbatch has a small contact area with the outside world, resulting in poor antibacterial and mildew-proofing effects. A higher addition amount is required, but a higher addition amount is costly and will cause more production problems during the extruder mixing process.

[0080] The present invention combines polyacrylonitrile, zinc acetate and DMF, and uses an electrospinning method to prepare a C / ZnO composite under specific spinning conditions. After carbonization, the product still maintains the fiber form of spinning. These fibrous substances can be inserted into the polypropylene molecular chain, making it more strongly bonded to the polymer, and the material has better dispersibility. The particle size range can still be maintained in the nanometer level during the dispersion process. A small amount of use can make the PP resin have excellent antibacterial and mildew-proof effects, and has the advantages of low improvement cost and easy promotion and implementation. The above is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A highly effective antibacterial and mildew-proof polypropylene masterbatch, characterized in that: By weight, it is composed of the following components: PP resin 55-95 parts 5-40 parts of antibacterial and antifungal agents Filler 0.1-20 parts 0.1-5 parts of additives; The antibacterial and mildew-proof agent is a C / ZnO composite prepared by electrospinning; The preparation method of the antibacterial and mildew-proof agent comprises the following steps: Step 101. Add the polymer carrier and the zinc salt in a weight ratio of 1:1-1.5 into a solvent, stir magnetically at 500-1000 rpm at room temperature for 5-10 minutes, and then ultrasonically disperse for 5-10 minutes to obtain a spinning solution. Step 102: transferring the spinning solution obtained in step 101 into a syringe for electrospinning to obtain antibacterial and mildew-proof masterbatch; Step 103. The antibacterial and mildew-proof masterbatch obtained in step 102 is spun in a protective gas environment at 600-1200° C. and carbonized for 3 hours to obtain an antibacterial and mildew-proof agent; In step 102, the diameter of the syringe needle is 0.1-0.5 mm, the electrospinning voltage is 30-40 kV, and the distance between the syringe needle tip and the receiving spinning copper plate is 20-30 cm; The polymer carrier is polyacrylonitrile, the zinc salt is zinc acetate, the solvent is DMF, the protective gas is a mixture of N2 and O2 in a volume ratio of 8-10:1, the filler is 1250 mesh calcium carbonate, and the additives are antioxidants and lubricants.

2. The method for preparing a high-efficiency antibacterial and mildew-proof polypropylene masterbatch according to claim 1, characterized in that: The following steps are involved: Step 201. Place the PP resin, antibacterial and mildew-proof agent, filler, and additive into a high-speed disperser in sequence and stir at room temperature at 250-800 rpm for 10-20 minutes to obtain a premix; Step 202. The premix obtained in step 201 is fed into a twin-screw extruder, and after passing through the twin-screw feeding section, conveying section, mixing section, negative pressure section and extrusion section, it is cooled and pelletized to obtain a high-efficiency antibacterial and mildew-proof polypropylene masterbatch.

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