WO2021175134A1

WO2021175134A1 - Antibacterial material containing a highly dispersed inorganic antibacterial agent and preparation method thereof

Info

Publication number: WO2021175134A1
Application number: PCT/CN2021/077478
Authority: WO
Inventors: Xingguang ZHANG; Wei Wang; Jin Zhang; Jun Yan
Original assignee: X-Germ Innovative Technology Inc.
Priority date: 2020-03-02
Filing date: 2021-02-23
Publication date: 2021-09-10

Abstract

The present application relates to an antibacterial material containing a highly dispersed inorganic antibacterial agent and preparation method thereof. The preparation method of the antibacterial material, prior to adding an inorganic antibacterial agent, firstly spreads a layer of the binder on the surface of the polymer matrix, so that the inorganic antibacterial agent adheres to the surface of the polymer matrix with the aid of the binder to improve combination of the inorganic antibacterial agent and polymer matrix. The preparation method can achieve a uniform loading of the inorganic antibacterial agent on the polymer matrix while ensuring a high loading of the inorganic antibacterial agent, and can also achieve an antibacterial effect equivalent to silver-loaded antibacterial agent.

Description

ANTIBACTERIAL MATERIAL CONTAINING A HIGHLY DISPERSED INORGANIC ANTIBACTERIAL AGENT AND PREPARATION METHOD THEREOF

TECHNICAL FIELD

The present application belongs to the field of antibacterial materials, especially relates to an antibacterial material containing a highly dispersed inorganic antibacterial agent and preparation method thereof.

BACKGROUND

An antibacterial masterbatch can be obtained by granulating an inorganic antibacterial agent and a polymer matrix, and uniformly dispersing the inorganic antibacterial agent in the polymer matrix. The antibacterial masterbatch can be processed with polymer chips and/or polymer particles into antibacterial products, such as an antibacterial yarn, an antibacterial non-woven fabric and plastic products in various forms.

At present, the antibacterial material and preparation method thereof in the prior art mainly have the following shortcomings:

1. Most antibacterial materials achieve a highly efficient antibacterial property through an inorganic silver-loaded antibacterial agent. However, the inorganic silver-loaded antibacterial agent is expensive, and may lead to a potential security risk in the case of accumulating to a certain amount in bodies. Moreover, the inorganic silver-loaded antibacterial agent is prone to oxidation and color degradation, which dramatically affects practical properties of antibacterial products such as color and transparency.

2. The inorganic antibacterial agent has a poor dispersity in the polymer matrix. The polymer chips and/or polymer particles are much larger in size than the inorganic antibacterial agent, resulting in a poor cohesion between the polymer and the inorganic antibacterial agent during processing especially during high temperature melting. In order to avoid a performance loss and defects of polymer products, the polymer matrix and the inorganic antibacterial agent need to be dried before processing, which is undoubtedly more unfavorable to the interface combination therebetween. In practice, it was found that it was difficult to uniformly load an inorganic antibacterial agent on a polymer matrix even by stirring. Besides, in the preparation process of the antibacterial material, most of the antibacterial powder is filled in a large number of pores formed by the accumulation of large-sized polymer matrix, and gradually transfers from the upper layer of the antibacterial material to the middle layer even to the bottom layer due to gravity, thus the upper layer of the obtained antibacterial material has a significantly lower content of inorganic antibacterial agent than that of the middle and bottom layer. Such uneven distribution of the inorganic antibacterial agent severely affects the antibacterial effect.

3. A dried inorganic antibacterial agent has an extremely low moisture content. Therefore, when the dried antibacterial agent is stirred and mixed with other raw materials, it is easy to generate flying dust, and the dust tends to suspend in the air to form an aerogel, which causes an unnecessary waste of resources, and also leads to an air pollution and a harsh production environment.

SUMMARY

In view of the above-mentioned problems of the prior art, the technical purpose of the present application is to provide an antibacterial material containing a highly dispersed inorganic antibacterial agent and preparation method thereof, aiming to fundamentally address the issue of an unevenly distribution of the inorganic antibacterial agent, due to the fact of poor dispersion and being prone-to-agglomeration of the inorganic antibacterial agent in the melt of polymer matrix.

In a first aspect, the present application provides a preparation method of an antibacterial masterbatch containing a highly dispersed inorganic antibacterial agent. The preparation method of the antibacterial masterbatch comprises the following steps:

performing a primary mixing treatment on the raw material including a polymer matrix and a binder to give a polymer matrix with at least part of the surface spreading the binder;

subjecting an inorganic antibacterial agent and the polymer matrix with at least part of the surface spreading the binder to a second mixing treatment to give a polymer matrix with the inorganic antibacterial agent adhered to the surface thereof; and

granulating the polymer matrix with the inorganic antibacterial agent adhered to the surface thereof into an antibacterial masterbatch.

The preparation method of the antibacterial masterbatch of the present application, prior to adding an inorganic antibacterial agent, firstly spreads a layer of the binder on the surface of the polymer matrix, so that the inorganic antibacterial agent adheres to the surface of the polymer matrix with the aid of the binder to improve combination of the inorganic antibacterial agent and polymer matrix. The preparation method can achieve a uniform loading of the inorganic antibacterial agent on the polymer matrix while ensuring a high loading of the inorganic antibacterial agent, and can also achieve an antibacterial effect equivalent to silver-loaded antibacterial agent. In addition, the preparation method enables the inorganic antibacterial agent to be protected by the binder, which not only prevents the antibacterial agent powder from generating a flying dust when stirring, but also improves a secondary water absorption of the inorganic antibacterial agent.

Preferably, the mass ratio of the polymer matrix and the binder is (60 to 90) : (0.5 to 5) , so that the inorganic antibacterial agent can be efficiently adhered to the surface of the polymer matrix.

Preferably, the mass ratio of the polymer matrix and the inorganic antibacterial agent is (60 to 90) : (1 to 30) .

Preferably, the binder may be selected from a group consisting of polyol, polymeric alcohol, polyester polyol and hydrocarbon mixture, wherein the hydrocarbon mixture has a carbon atom number between 12 and 36. The above-mentioned binder has a long carbon chain, which facilitates the dispersion of the inorganic antibacterial agent under high temperature and prevents agglomeration. The binder may further preferably be at least one of anhydrous glycerin, liquid paraffin and white wax.

Preferably, the inorganic antibacterial agent is selected from a group consisting of CuO, ZnO, TiO ₂, SiO ₂, Al ₂O ₃, WO ₃, ZrO ₂, V ₂O ₃, SnO ₂, FeO and Fe ₃O ₄. The particle size of the inorganic antibacterial agent may be 25 nm to 2 μm.

Preferably, the preparation method of the antibacterial masterbatch comprises the following steps:

performing a primary mixing treatment on the raw material including a polymer matrix and a portion of a binder to give a polymer matrix with at least part of the surface spreading the binder;

subjecting the polymer matrix with at least part of the surface spreading the binder, and a portion of an inorganic antibacterial agent to a second mixing treatment to give a polymer matrix with the inorganic antibacterial agent adhered to the surface thereof;

performing a third mixing treatment on the polymer matrix with the inorganic antibacterial agent adhered to the surface thereof and the rest of the binder to obtain a polymer matrix with the binder re-spread on the surface;

subjecting the rest of the inorganic antibacterial agent and the polymer matrix with the binder re-spread on the surface to a fourth mixing treatment to obtain a polymer matrix on which the inorganic antibacterial agent is re-adhered to the surface; and

granulating the polymer matrix on which the inorganic antibacterial agent is re-adhered to the surface into an antibacterial masterbatch.

Preferably, wherein the binder of the primary mixing treatment is 20%to 80%of the total mass of the binder, and the inorganic antibacterial agent of the second mixing treatment is 25%to 80%of the total mass of the inorganic antibacterial agent.

Preferably, the primary mixing treatment and/or second mixing treatment has a mixing speed of 30 to 3000 revolutions per minute, and a mixing time of 1 to 60 minutes. Keeping the mixing speed and mixing time within the above range can reduce an energy loss while avoiding uneven mixing. The mixing speed can preferably be 60 to 300 revolutions per minute.

Preferably, in addition to the polymer matrix and the binder, the raw material for the primary mixing treatment also includes a dispersant, wherein the mass ratio of the polymer matrix to the dispersant is (60 to 90) : (0 to 5) .

Preferably, the polymer matrix is thermoplastic resin. The thermoplastic resin is more conducive to granulation of the antibacterial masterbatch.

In a second aspect, the present application provides an antibacterial masterbatch containing a highly dispersed inorganic antibacterial agent obtained from any one of the preparation methods mentioned above.

In a third aspect, the present application provides a preparation method of antibacterial yarn without significantly reducing the breaking strength of yarn. The preparation method comprises the following steps:

spinning the polymer matrix with the inorganic antibacterial agent adhered to the surface thereof into an antibacterial yarn.

The preparation method of the antibacterial yarn mentioned above can improve the uniform dispersion of the inorganic antibacterial agent on the surface and inside of the antibacterial yarn, and more importantly, it will not lead to a significant decrease in the breaking strength of the antibacterial yarn, which is beneficial to obtain a stable and lasting antibacterial effect and maintain a high mechanical strength.

Preferably, the inorganic antibacterial agent has a dispersion size of 300 nm or less in the antibacterial yarn. The dispersion size can prevent the inorganic antibacterial agent from presenting on the surface or inside of the yarn in the form of large particles, resulting in a poor antibacterial property, a rough surface, an uneven mechanical property and other defects of the yarn. Preferably, the dispersion size of the inorganic antibacterial agent in the antibacterial yarn is 100 to 300 nm.

Preferably, the preparation method of the antibacterial yarn does not comprise a step of preparing an antibacterial masterbatch using raw material including a polymer matrix, a binder and an inorganic antibacterial agent prior to spinning. The step of preparing an antibacterial masterbatch not only leads to a complicated process and an increased cost, but also leads to limited contact time between the inorganic antibacterial agent and other spinning raw materials in the spinning equipment. Moreover, large-size antibacterial masterbatches and other spinning materials only have macroscopic collisions but little microscopic contact, which makes it difficult to achieve a uniform dispersion of the inorganic antibacterial agent on the surface and inside of the antibacterial yarn.

Preferably, the polymer matrix is polyester polymer and/or polyamide polymer.

In a fourth aspect, the present application provides a preparation method of a polyolefin antibacterial masterbatch. The preparation method comprises the following steps:

mixing a dispersant and a binder to obtain a first mixture in which the binder is evenly spread on the surface of the dispersant;

adding an inorganic antibacterial agent to the first mixture, and continue mixing to obtain a second mixture in which the inorganic antibacterial agent is uniformly adhered to the surface of the dispersant;

subjecting the second mixture to a first granulation treatment;

subjecting polyolefin matrix and particle obtained from the first granulation treatment to a second granulation treatment to obtain a polyolefin antibacterial masterbatch.

The purpose of the first granulation treatment is to melt the dispersant under high temperature during granulation, and promote the rapid spread of the inorganic antibacterial agent adhering to the surface of the dispersant to form an efficient dispersion system. It is preferable to use a dispersant having a carbon chain structure. This is because the main chain of the polyolefin matrix also has a carbon chain structure, and the similar structure of the polyolefin matrix and dispersant makes the polyolefin antibacterial masterbatch able to obtain a good interface compatibility without compatibilizers.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram of the preparation method of an antibacterial masterbatch (the granulation is not shown in FIG. 1) , in which 1 refers to a polymer matrix, 2 refers to an inorganic antibacterial agent, and 3 refers to a binder;

FIG. 2 is a sectional scanning electron microscope image of the antibacterial masterbatch obtained from example 1;

FIG. 3 is a sectional scanning electron microscope image of the antibacterial masterbatch obtained from example 2;

FIG. 4 is a sectional scanning electron microscope image of the antibacterial masterbatch obtained from example 3;

FIG. 5 is a sectional scanning electron microscope image of the antibacterial masterbatch obtained from example 4;

FIG. 6 is a sectional scanning electron microscope image of the antibacterial masterbatch obtained from comparative example 1;

FIG. 7 is a sectional scanning electron microscope image of the antibacterial masterbatch obtained from comparative example 2;

FIG. 8 is a sectional scanning electron microscope image of the antibacterial yarn obtained from example 5;

FIG. 9 is a sectional scanning electron microscope image of the antibacterial yarn obtained from example 6;

FIG. 10 is a sectional scanning electron microscope image of the antibacterial yarn obtained from example 7;

FIG. 11 is a sectional scanning electron microscope image of the polyolefin antibacterial masterbatch obtained from example 8;

FIG. 12 is a sectional scanning electron microscope image of the polyolefin antibacterial masterbatch obtained from example 9;

FIG. 13 is a sectional scanning electron microscope image of the polyolefin antibacterial masterbatch obtained from example 10;

FIG. 14 is an image of Table 1, and Table 1 shows the antibacterial rate of plastic sheets prepared from antibacterial masterbatches of examples 1-4 against Escherichia coli and Staphylococcus aureus;

FIG. 15 is an image of Table 2, and Table 2 shows the breaking strength of antibacterial yarns obtained from examples 5-7 and corresponding comparative yarns;

FIG. 16 is an image of Table 3, and Table 3 shows the antibacterial rate of antibacterial fabrics prepared from antibacterial yarns of examples 5-7 against Escherichia coli and Staphylococcus aureus;

FIG. 17 is an image of Table 4, and Table 4 shows the antibacterial rate of the antibacterial fabric prepared from antibacterial yarn of example 7 against Staphylococcus aureus and Pneumoniae after several times of washing;

FIG. 18 is an image of Table 5, and Table 5 shows the antibacterial rate of plastic sheets prepared from polyolefin antibacterial masterbatches of examples 8-10 against Escherichia coli and Staphylococcus aureus.

DETAILED DESCRIPTION

The present invention will be further described with the following examples below. It should be understood that the following examples are only used for explaining this invention, and do not limit this invention.

In order to obtain an excellent antibacterial effect, antibacterial masterbatch typically uses a nano-scale inorganic antibacterial agent with a large specific surface area. For example, the size of the inorganic antibacterial agent may be 25 nm to 2 μm, preferably 50 to 200 nm. However, the size of polymer chips or polymer particles is usually on the order of millimeters, such as 1 to 4 mm. During compounding of the inorganic antibacterial agent and the polymer matrix, since the physical sizes of the inorganic antimicrobial agent and the polymer matrix differ greatly, the inorganic antibacterial agent easily agglomerates in the melt of the polymer matrix and is difficult to achieve a uniform dispersion. The inventors found in practice that the antibacterial masterbatch prepared by using the inorganic antibacterial agent and the polymer matrix often appears delamination, which is even more pronounced when no binder is used. This is also the most important technical problem that the present application aims to address.

The preparation method of the antibacterial masterbatch of the present application first spreads a layer of binder on the surface of the polymer matrix to facilitate the uniform distribution of the subsequently added inorganic antibacterial agent on the surface of the polymer matrix. The binder with a long chain structure is more helpful for the dispersion of the inorganic antibacterial agent in the molten system generated by heating and melting the polymer during granulation.

The polymer matrix can be a high molecular polymer that can form a fluid melt after the temperature reaches the melting point, preferably a thermoplastic resin. The polymer matrix includes but is not limited to polyolefin, modified polyolefin, polyester, polyamide, polylactic acid, poly (butylene succinate) and other engineering polymers. The polyolefin includes but is not limited to polyethylene, polypropylene, polyvinyl chloride, polyacrylonitrile and polyvinylidene fluoride, etc. The modified polyolefin may be maleic anhydride modified polyolefin, such as maleic anhydride modified polyethylene and/or maleic anhydride modified polypropylene. The polyester includes but is not limited to polyethylene terephthalate, polytrimethylene terephthalate, polybutylene terephthalate and polyethylene naphthalate, etc. The polyamide includes but is not limited to polyamide-6, polyamide-66, polyamide-610 and polyamide-1010, etc. Other engineering polymers include polyacrylonitrile-butadiene-styrene, polystyrene, styrene acrylonitrile, polycarbonate, polymethyl methacrylate, polyether ether ketone and polyphenylene sulfide, etc.

The inorganic antibacterial agent includes but is not limited to one or a mixture of CuO, ZnO, TiO ₂, SiO ₂, Al ₂O ₃, WO ₃, ZrO ₂, V ₂O ₃, SnO ₂, FeO and Fe ₃O ₄. In some examples, the inorganic antibacterial agent is surface-treated with a coupling agent. The type of the coupling agent is not limited, and can be a silane coupling agent, titanate coupling agent or rare earth coupling agent. The absolute dry mass ratio of the coupling agent to the inorganic antibacterial agent is 0.5%to 20%, preferably 0.5%to 3%. It should be understood that the coupling agent can also be replaced by other surfactants or modifiers. The particle size of the inorganic antibacterial agent is preferably 25 to 350 nm, and more preferably 30 to 100 nm.

The binder of the present application has the following characteristics: being liquid with a good fluidity at room temperature; having a high boiling point; having a stable chemical property, especially having no volatilization, decomposition and carbonization at the molten temperature of the polymer matrix; having a good affinity for the polymer matrix and the inorganic antibacterial agent, in particular having a good compatibility with the melt of the polymer matrix.

The binder may be selected from a group consisting of polyol, polymeric alcohol, polyester polyol and hydrocarbon mixture. The above-mentioned binder has the following advantages: 1. preventing the binder with an excessive water content from causing the polymer matrix to decompose during granulation, resulting in a decrease in the quality of the masterbatch; 2. avoiding the use of a binder with a low boiling point, resulting in a decrease in the quality of the masterbatch; 3. avoiding the use of colored binder or discoloration of the binder during granulation, thereby affecting product performance; 4. avoiding the toxic and side effects of the binder to harm product performance or ecological environment. It is more preferable to use hydrocarbon mixture with a carbon atom number between 12 and 36. The polyol and polymeric alcohol can be glycerol (with a water content less than 1%) , polyethylene glycol (with a water content less than 1%, such as PEG-200, PEG-300, PEG-400, PEG-600, PEG-800, PEG-1000, PEG-1500) , and polyvinyl alcohol (with a water content less than 1%) ; the polyester polyol can be propylene glycol methyl ether acetate (CAS number: 108-65-6) . In some examples, the hydrocarbon mixture may be at least one of liquid paraffin (distillation temperature is more than 300 ℃; CAS number is 8042-47-5; for example, the liquid paraffin is purchased from Shanghai Macklin Biochemical Co., Ltd) , anhydrous glycerol (distillation temperature is 150 to 250 ℃; CAS Number is 56-81-5) , and white wax (distilled temperature is 150 to 250 ℃; CAS number is 8012-89-3; for example, the white wax is purchased from Sinopec Group) .

The raw material of the antimicrobial masterbatch may further comprise a dispersant or other additive. The kind of the dispersant is not limited, and can be a common dispersant in the art. In some examples, the dispersant may be selected from at least one of polyethylene wax (preferably, the molecular weight is 1,500 to 5,000, and CAS Number is 9002-88-4) , carboxylate polyethylene wax, oxidized polyethylene wax, polyacid, polycarboxylate acid (preferably polycarboxylate acid with a molecular weight of 3,000 to 15,000) , stearic acid, calcium stearate, zinc stearate, cadmium stearate, and N, N'-ethylene bisstearamide.

The preparation method of the antibacterial masterbatch containing a highly dispersed inorganic antibacterial agent is illustrated exemplarily below referring to FIG. 1.

Each raw material is respectively weighed in accordance with the raw material composition of the antibacterial masterbatch. For example, the raw material composition of the antibacterial masterbatch includes: in parts by mass, 60 to 90 parts of polymer matrix, 1 to 30 parts of inorganic antibacterial agent, 0.5 to 5 parts of binder, and 0 to 5 parts of dispersant. Preferably, the antibacterial masterbatch is based on 100 parts by mass of all the raw material. The raw material other than the binder is dried before use. It is described herein that the parts by mass of the above-mentioned raw material refer to the parts by mass of the raw material after drying.

A polymer matrix and a binder are subjected to a primary (first) mixing treatment, so that the binder is spread on the surface of the polymer matrix. The “spread” described herein refers to “make the binder at least partially infiltrate the surface of the polymer matrix, and preferably form a binder layer on the overall surface of the polymer matrix” . In the case of using a dispersant, the polymer matrix, the binder and the dispersant can be mixed together, thus also spreading a binder layer on the surface of the dispersant. In some examples, 0.5 to 3 parts of the binder is added to 60 to 90 parts of the polymer matrix and 0 to 5 parts of the dispersant, and then mixed evenly in a mixing equipment to obtain a polymer matrix with at least part of the surface spreading the binder (referred to as “particle A” ) .

A portion of an inorganic antibacterial agent and the polymer matrix with at least part of the surface spreading the binder (particle A) are subjected to a second mixing treatment to give a polymer matrix with the inorganic antibacterial agent adhered to the surface thereof (referred to as “particle A+” ) . In some examples, 0.5 to 20 parts of inorganic antibacterial agent is added to the polymer matrix with at least part of the surface spreading the binder and then mixed.

The rest of the binder is added to the polymer matrix with the inorganic antibacterial agent adhered to the surface thereof (particle A+) and subjected to a third mixing treatment to give a polymer matrix with the binder re-spread on the surface (referred to as “particle A+ Plus” ) . The third mixing treatment is essentially equivalent to repeating the primary mixing treatment. The primary mixing treatment can be repeated twice or more.

The rest of the inorganic antibacterial agent is added to the polymer matrix with the binder re-spread on the surface (particle A+ Plus) and subjected to a fourth mixing treatment to obtain a polymer matrix on which the inorganic antibacterial agent is re-adhered to the surface (referred to as “particle A+Plus Max” ) . Similarly, the fourth mixing treatment is essentially equivalent to repeating the second mixing treatment. The second mixing treatment can be repeated twice or more.

The above mixing treatment may use a conventional mixing equipment, such as a low-speed mixer or high-speed mixer. The mixing can be carried out at room temperature. The mixing speed may be 30 to 3000 revolutions per minute, preferably 60 to 300 revolutions per minute. The mixing time may be 1 to 60 minutes.

The polymer matrix on which the inorganic antibacterial agent is re-adhered to the surface is granulated into an antibacterial masterbatch through a granulation equipment. The granulation equipment includes but is not limited to a single-screw extruder, double-screw extruder, and double layer extruder, etc. The polymer matrix on which the inorganic antibacterial agent is re-adhered to the surface is placed in a granulation equipment to produce an antibacterial masterbatch through high temperature melting, screw conveying, extruding, cooling, pelletizing and drying. The heating temperature of the granulation equipment is adjusted adaptively depending on the type of the polymer matrix. For example, the granulation temperature of polyolefin matrix, polyamide-6 matrix, polyethylene terephthalate matrix is respectively 120 to 260 ℃, 180 to 260 ℃, 240 to 280 ℃.

Through the method mentioned above, the antibacterial masterbatch can be loaded with a high content of inorganic antibacterial agent while obtaining an antibacterial masterbatch containing a highly dispersed inorganic antibacterial agent. In some examples, the binder for the primary mixing treatment is 20%to 80%of the total mass of the binder. Controlling the mass ratio of the binder for the first mixing treatment within the above range can prevent part of the binder from failing to effectively bond or the binder from not being fully spread on the surface of the polymer matrix, resulting in uneven dispersion of the inorganic antibacterial agent. In addition, the inorganic antibacterial agent for the second mixing treatment is 25%to 80%of the total mass of the inorganic antibacterial agent. Controlling the mass ratio of the inorganic antibacterial agent for the second mixing treatment within the above range can prevent excessive inorganic antibacterial agent from forming saturated adhesion on the surface of the polymer matrix, resulting in flying dust due to ineffective adhesion of part of the antibacterial agent, and also reduce the dispersion uniformity of the inorganic antibacterial agent in the polymer matrix. Besides, too few inorganic antibacterial agents for the second mixing treatment will inevitably lead to more inorganic antibacterial agent added later, which will also cause flying dust and uneven dispersion.

It is worth noting that the inorganic antibacterial agent or binder can also be added all at once. But when the antibacterial masterbatch is loaded with a high content of inorganic antibacterial agent, for example, taking the mass parts of all the raw material of the antibacterial masterbatch as 100 parts, when the mass parts of the inorganic antibacterial agent are 12 parts or more, the binder and inorganic antibacterial agent are preferably added and mixed for multiple times. It should be understood that the binder and the inorganic antibacterial agent are not limited to the mixing process by adding twice, and can also be processed by adding more than twice.

It should be noted that replacing the inorganic antibacterial agent with other inorganic powder such as calcium carbonate, talcum powder, aluminum hydroxide, magnesium oxide, metal powder, inorganic pigments, carbon powder, graphite powder and fine carbon fiber is also applicable to the present application, and can also obtain a masterbatch product with evenly dispersed inorganic powder.

Preparation method of an antibacterial yarn in the prior art mainly includes melt spinning, fabric finishing and blend spinning. The melt spinning method needs to prepare an antibacterial masterbatch prior to spinning, while the dispersion degree of the antibacterial agent of antibacterial yarn is limited by the dispersion of antibacterial masterbatch in a spinning equipment. The antibacterial agent of the antibacterial yarn obtained by fabric finishing, has a low adsorption strength or a weak chemical bond connection on the surface of the yarn, causing the antibacterial agent easily being detached from the surface of the yarn. The antibacterial agent must be added to the spinning solution for blend spinning, and that greatly affect the physical properties of the spinning solution. In view of this, a preparation method of the antibacterial yarn is provided by the present application, which can realize a uniform dispersion of the inorganic antibacterial agent in the yarn, and also achieve a stable and long-lasting antibacterial effect with a small amount of the inorganic antibacterial agent. Moreover, the breaking strength of the antibacterial yarn is not significantly reduced by the addition of the inorganic antibacterial agent.

The raw material composition of the antibacterial yarn includes: in parts by mass, 97 to 99.76 parts of polymer matrix, 0.2 to 1 part of inorganic antibacterial agent, 0 to 1 part of dispersant, and 0.04 to 1 part of binder. The polymer matrix of the antibacterial yarn is preferably polyester and/or polyamide. The polyester includes but is not limited to at least one of polyethylene terephthalate, polytrimethylene terephthalate, polybutylene terephthalate and polyethylene naphthalate. The polyamide includes but is not limited to at least one of polyamide-6, polyamide-66, polyamide-610 and polyamide-1010. The inorganic antimicrobial agent, dispersant and binder of the antimicrobial yarn are substantially the same as the antibacterial masterbatch, and that will not be further described herein.

The polymer matrix, inorganic antibacterial agent, dispersant, and binder are mixed referring to the preparation method of the antibacterial masterbatch. The mixture is then spun into a highly effective antibacterial yarn without significantly reducing the breaking strength thereof. The spinning is a conventional yarn production process, which belongs to known technology for a person skilled in the art. For example, yarns and fabrics can be prepared in accordance with "Textile Materials Science (Fourth Edition) " published by China Textile Press.

The macro morphological structure (refers to the structure that can be observed by optical microscope) of the antibacterial yarn includes a skin-core structure and/or cross-sectional structure. The cross-section may be circular, oval or spiral. Preferably, the macromorphological structure of the antibacterial yarn is skin-core structure with a circular cross-section. More preferably, the inorganic antibacterial agent is distributed on the surface layer of the skin-core structure of the antibacterial yarn, and the core layer does not contain the inorganic antibacterial agent.

The present application also provides an antibacterial fabric, the yarn material of which includes an antibacterial yarn that do not significantly reduce the breaking strength of the yarn and ordinary yarn. Wherein, the mass ratio of the antibacterial yarn to the yarn raw material is 20 to 100 %. According to National Standard GB/T 20944.2-2007 “Textiles-Evaluation for antibacterial activity-Part 2: Absorption method” , the antibacterial rate of the antibacterial fabric against Escherichia coli and Staphylococcus aureus is greater than 99%.

The present application adopts the following method to characterize the distribution of the inorganic antibacterial agent in antibacterial yarn: measuring the radial surface of the yarn by the ImageJ software (version number 1.8.0) developed by National Institutes of Health (NIH) ; obtaining the scanning electron microscope image of the yarn with an electron microscope (Phenom) , and counting the inorganic antimicrobial agent at a magnification of 5,000 to 10,000, to calculate the diameter of the inorganic antibacterial agent in the yarn. The specific calculation is as follows: determining the gray threshold of each other according to the difference in the gray value of the inorganic antibacterial agent and the polymer matrix in the scanning electron micrograph image; for example, 125 to 255 for the inorganic antibacterial agent and 125 or less for the polymer matrix; and then calculating the ratio of pixels occupied by the inorganic antibacterial agent to pixels of sampling area, or reverse-calculating the diameter of the inorganic antibacterial agent by the pixel number. The pixel calculation method is to select a scanning electron micrograph image, which has a length of L pixel and width of W pixel, and the pixel of the image is the product of L pixel and W pixel. Taking the area of 1 pixel multiplied by 1 pixel as the smallest unit, the pixel of the antimicrobial agent in the scanning electron micrograph image is divided by the pixel of the entire scanning electron micrograph image, and the result is recorded as the distribution ratio of the inorganic antibacterial agent on the radial surface of the yarn (the unit is ppmp, i.e., pixels per million pixels) . The value calculated through the reverse calculation of the pixels number is the average diameter of the inorganic antibacterial agent in the yarn (i.e., the dispersion size) . In some cases, due to measurement noise or other factors, the gray threshold difference between the inorganic antibacterial agent and the polymer matrix is not significant, so it is necessary to enlarge the characteristics of the inorganic antibacterial agent in the scanning electron micrograph image through sparse matrix.

The distribution ratio of the inorganic antibacterial agent on the radial surface of the yarn is preferably 100 to 200 ppmp, or 150 to 3,000 ppmp, or 2,000 to 9,000 ppmp, or 5,000 to 20,000 ppmp. The average diameter of the inorganic antibacterial agent in the yarn (i.e., the dispersion size) is preferably 150 to 300 nm, or 170 to 350 nm, or 220 to 440 nm.

In order to control the dispersion size of the inorganic antibacterial agent in antibacterial yarn, the key is the core steps of the preparation method of the antibacterial yarn, combining with the physical and chemical characteristics and dosage of the selected binder, which enables the antibacterial agent fully contact with the polymer matrix at the micro level, so as to achieve fully dispersion.

The inorganic antibacterial agent, although has a small particle size, but remains solid at a melt temperature of the polyolefin, and the hydrophobic surface of the polyolefin makes the liquidity melt generated by melting have an extremely low surface free energy and surface tension, so it is difficult for the inorganic antibacterial agent to spread and infiltrate on the surface of the polyolefin melt, thus leading to a poor antibacterial effect of the polyolefin antibacterial masterbatch. The application also provides a preparation method of the polyolefin antibacterial masterbatch, which fundamentally solves the problem that the uneven dispersion of the inorganic antibacterial agent in the polyolefin matrix causing an unsatisfactory effect of the polyolefin antibacterial masterbatch.

In some examples, the raw material composition of the polyolefin antibacterial masterbatch includes: in parts by mass, 56 to 92 parts of polyolefin matrix, 5 to 30 parts of inorganic antibacterial agent, 2 to 10 parts of dispersant, and 1 to 4 parts of binder. Preferably, the mass parts of all the raw material are 100 parts. The polyolefin matrix includes but is not limited to one or more of polypropylene, polyethylene, polyvinyl chloride, ethylene copolymer, and propylene copolymer. The ethylene copolymer includes but is not limited to ethylene-vinyl acetate copolymer, ethylene-styrene copolymer or ethylene-maleic anhydride copolymer; the propylene copolymer includes but not limited to propylene-ethylene random copolymer, propylene-ethylene block copolymer or grafted polypropylene. The inorganic antimicrobial agent, dispersant and binder of the polyolefin antibacterial masterbatch are substantially the same as the antimicrobial yarn, and that will not be further described herein. It should be noticed that the stearic acid dispersants such as stearic acid and calcium stearate are not suitable for the preparation of the polyolefin antibacterial masterbatch. Because of the poor thermal stability of the stearic acid dispersants, they tend to decompose and deteriorate at high temperature. Preferably, the dispersant has a melting point of 105 to 165 ℃, and more preferably 120 to 165 ℃. In some examples, the particle size of the inorganic antibacterial agent is 25 nm to 5 μm.

In the preparation of the polyolefin antibacterial masterbatch, the mass ratio of the dispersant, the binder and the inorganic antibacterial agent may be 2-10: 1-4: 5-30. The inorganic antibacterial agent has an excellent dispersing effect in the polyolefin antibacterial masterbatch and the granulation is relatively stable.

In some examples, the mass ratio of the inorganic antibacterial agent of the polyolefin antibacterial masterbatch is 5%to 30%. When the mass ratio of the inorganic antibacterial agent is less than 5%, the antibacterial masterbatch as a concentrated carrier for the antibacterial agent, shows a poor antibacterial effect. When the mass ratio of the inorganic antibacterial agent is more than 30%, both the first granulation treatment and the second granulation treatment have a poor production stability. It was found that during the experiment when the inorganic antibacterial agent is excessive, the sample obtained by cooling the mixed melt from the extrusion port of an extruder with water, has a relatively poor overall strength and tends to break. The reason is that the inorganic antibacterial agent has a small particle size and a relatively large specific surface area, leading to a decrease in the overall strength of the sample when the inorganic antibacterial agent is excessive.

The preparation method of the polyolefin antibacterial masterbatch will be exemplarily described below.

The polyolefin matrix, inorganic antibacterial agent and dispersant are dried in a drying equipment. The dispersant and the binder are mixed evenly to obtain a first mixture (a mixture of the dispersant and binder) . The inorganic antibacterial agent is added to the first mixture and mixed to obtain a second mixture. The second mixture is put into a granulation equipment, and granulated in a particle after high temperature melting, screw conveying, extruding, cooling, pelletizing and drying (a first granulation treatment) . The particle obtained from the first granulation treatment is a mixture of the dispersant, binder and inorganic antibacterial agent. The first granulation temperature is preferably 110 to 190 ℃. In some examples, the first granulation temperature is higher than the melting point of the dispersant by 5 to 30 ℃, so as to ensure that the dispersant is fully melted within the temperature range and at the same time avoid excessive temperature causing an energy waste. The particle obtained from the first granulation treatment is mixed well with the polyolefin matrix, and then subjected to a second granulation treatment. The second granulation temperature is preferably 160 to 260 ℃. A person skilled in the art can adjust the second granulation temperature according to the polyolefin. The mass ratio of the particle obtained from the first granulation treatment and the polyolefin matrix can be 44: 56 to 8: 92.

In actual production, it is necessary to dry the particle after each granulation. The good dispersion effect of the inorganic antibacterial agent of the polyolefin antibacterial masterbatch is mainly due to the following reasons: on one hand, the antibacterial agent is adhered on the surface of the dispersant with the aid of the binder, so during the first granulation treatment and the second granulation treatment, the melted dispersant mainly acts on the antibacterial agent to promote the dispersion effect; on the other hand, the inorganic antibacterial agent can be more fully dispersed through the two granulation treatment.

In conclusion, the preparation method of the present application realizes the efficient dispersion of the inorganic antimicrobial agent in the antimicrobial material through reasonably setting the addition sequence of the binder and the inorganic antibacterial agent, i.e., firstly adding the binder to the polymer matrix to spread the binder on the surface of the polymer matrix (polymer matrix and dispersant) and then adding the inorganic antibacterial agent to adhere the inorganic antibacterial agent on the surface of the polymer matrix (polymer matrix and dispersant) .

Hereinafter, the present invention will be better described with the following representative examples. It should be understood that the following examples are used to explain this invention and do not limit the scope of this invention. Any non-essential improvements and modifications made by a person skilled in the art based on this invention all fall into the protection scope of this invention. The specific parameters below are only exemplary, and a person skilled in the art can choose proper values within an appropriate range according to the description of this article, and are not restricted to the specific values cited below. In the following examples and comparative examples, nano zinc oxide has an average particle size of 25 to 100 nm.

Example 1: polyamide-6 antibacterial masterbatch and its preparation

Polyamide-6 (PA6) resin, nano zinc oxide and polyethylene wax were dried in a drying equipment before use. The raw material composition of the polyamide-6 antibacterial masterbatch includes: in parts by mass, 87.5 parts of polyamide-6 resin, 10 parts of nano zinc oxide, 1 part of polyethylene wax and 1.5 parts of anhydrous glycerin.

87.5 parts of polyamide-6 resin, 1 part of polyethylene wax and 0.5 part of anhydrous glycerol were evenly mixed to give a mixture I (referred to as “particle A” ) . 5 parts of nano zinc oxide was subsequently added to the mixture I and then mixed to obtain a mixture II (referred to as “particle A+” ) . And then 1 part of anhydrous glycerol was added to the mixture II and further mixed evenly to produce a mixture III (referred to as “Particle A+Plus” ) . Finally, 5 parts of nano zinc oxide was added to the mixture III and then mixed evenly to give a mixture IV (referred to as “Particle A+Plus Max” ) . In each of the mixing process mentioned above, the mixing speed was 150 revolutions per minute and the mixing time was 20 minutes. The mixture IV was granulated using a twin-screw extruder. After high-temperature melting, screw conveying, extruding, cooling, pelletizing and drying, polyamide-6 antibacterial masterbatch was obtained. The temperature of each temperature zone of twin-screw extruder respectively were: 220 ℃ in the first section, 230 ℃in the second section, 250 ℃ in the third section, 250 ℃ in the fourth section, and 260 ℃ in the fifth section.

Example 2: polypropylene antibacterial masterbatch and its preparation

Polypropylene (PP) resin, nano titanium dioxide and oxidized polyethylene wax were dried in a drying equipment before use. The raw material composition of the polypropylene antibacterial masterbatch includes: in parts by mass, 80 parts of polypropylene resin, 15 parts of nano titanium dioxide, 1.5 parts of oxidized polyethylene wax and 3.5 parts of liquid paraffin.

80 parts of polypropylene resin, 1.5 parts of oxidized polyethylene wax and 2 parts of liquid paraffin were evenly mixed to give a mixture I (referred to as “particle A” ) . 5 parts of nano titanium dioxide was subsequently added to the mixture I and then mixed to obtain a mixture II (referred to as “particle A+” ) . And then 1.5 parts of liquid paraffin was added to the mixture II and further mixed evenly to produce a mixture III (referred to as “Particle A+Plus” ) . Finally, 10 parts of nano titanium dioxide was added to the mixture III and then mixed evenly to give a mixture IV (referred to as “Particle A+Plus Max” ) . In each of the mixing process mentioned above, the mixing speed was 150 revolutions per minute and the mixing time was 20 minutes. The mixture IV was granulated using a twin-screw extruder. After high-temperature melting, screw conveying, extruding, cooling, pelletizing and drying, polypropylene antibacterial masterbatch was obtained. The temperature of each temperature zone of twin-screw extruder respectively were: 180 ℃ in the first section, 200 ℃ in the second section, 220 ℃ in the third section, 220 ℃ in the fourth section, and 250 ℃ in the fifth section.

Example 3: polyethylene terephthalate antibacterial masterbatch and its preparation

Polyethylene terephthalate (PET) resin and nano zinc oxide were dried in a drying equipment before use. The raw material composition of the polyethylene terephthalate antibacterial masterbatch includes: in parts by mass, 71 parts of polyethylene terephthalate resin, 25 parts of nano zinc oxide and 4 parts of liquid paraffin. Wherein, the nano zinc oxide is surface modified by a silane coupling agent KH570 (CAS number is 2530-85-0) , and the mass ratio of the silane coupling agent to the nano zinc oxide is 3%.

71 parts of polyethylene terephthalate resin and 3 parts of liquid paraffin were evenly mixed to give a mixture I (referred to as “particle A” ) . 15 parts of nano zinc oxide was subsequently added to the mixture I and then mixed to obtain a mixture II (referred to as “particle A+” ) . And then 1 part of liquid paraffin was added to the mixture II and further mixed evenly to produce a mixture III (referred to as “Particle A+Plus” . Finally, 10 parts of nano zinc oxide was added to the mixture III and then mixed evenly to give a mixture IV (referred to as “Particle A+Plus Max” ) . In each of the mixing process mentioned above, the mixing speed was 150 revolutions per minute and the mixing time was 20 minutes. The mixture IV was granulated using a twin-screw extruder. After high-temperature melting, screw conveying, extruding, cooling, pelletizing and drying, polyethylene terephthalate masterbatch was obtained. The temperature of each temperature zone of twin-screw extruder respectively were: 262 ℃ in the first section, 265 ℃ in the second section, 265 ℃ in the third section, 265 ℃ in the fourth section, and 270 ℃ in the fifth section.

Example 4: polyamide-6 antibacterial masterbatch and its preparation

Polyamide-6 (PA6) resin, nano zinc oxide and polyethylene wax were dried in a drying equipment before use. The raw material composition of the polyamide-6 antibacterial masterbatch includes: in parts by mass, 87 parts of polyamide-6 resin, 10 parts of nano zinc oxide, 1 part of polyethylene wax and 2 parts of liquid paraffin.

87 parts of polyamide-6 resin, 1 part of polyethylene wax and 2 parts of liquid paraffin were evenly mixed to give a mixture I (referred to as “particle A” ) . 10 parts of nano zinc oxide was subsequently added to the mixture I and then mixed to obtain a mixture II (referred to as “particle A+” ) . In each of the mixing process mentioned above, the mixing speed was 150 revolutions per minute and the mixing time was 20 minutes. The mixture II was granulated using a twin-screw extruder. After high-temperature melting, screw conveying, extruding, cooling, pelletizing and drying, polyamide-6 masterbatch was obtained. The temperature of each temperature zone of twin-screw extruder respectively were: 220 ℃ in the first section, 230 ℃ in the second section, 250 ℃ in the third section, 250 ℃ in the fourth section, and 260 ℃ in the fifth section.

It can be seen from Fig. 2 to Fig. 5 that the inorganic antibacterial agent is uniformly dispersed in the antibacterial masterbatch.

The antibacterial masterbatches obtained from examples 1-4 were respectively mixed with the corresponding polymers using a high-speed mixer. The mixing speed was 3000 revolutions per minute and the mixing time was 5 minutes. After the mixing was completed, the mixture was melted in a single-screw extruder, and the obtained melt was poured into a mold with a size of 50 mm × 70 mm × 4 mm, and cooled to form a plastic sheet. The mass fraction of the inorganic antibacterial agent of the plastic sheet is 1%. The polymer for preparing the plastic sheet is the same as the polymer matrix for preparing the antibacterial masterbatch in each example. According to GB/T 31402-2015 “Plastics-Measurement of antibacterial activity on plastics surfaces” , the antibacterial rate of plastic sheets against Escherichia coli and Staphylococcus aureus was tested. The test results are shown in Fig. 14 (i.e., Table 1) .

It can be seen from Table 1 that the plastic sheets prepared from the antibacterial masterbatches of examples 1-4 have an antibacterial rate of 90%or more against Escherichia coli and Staphylococcus aureus.

Comparative example 1

Polyamide-6 (PA6) resin, nano zinc oxide and polyethylene wax were dried in a drying equipment before use. The raw material composition of the polyamide-6 antibacterial masterbatch includes: in parts by mass, 87.5 parts of polyamide-6 resin, 10 parts of nano zinc oxide and 1 part of polyethylene wax.

87.5 parts of polyamide-6 resin, 1 part of polyethylene wax and 5 parts of nano zinc oxide were evenly mixed to give a mixture I . And then 5 parts of nano zinc oxide was subsequently added to the mixture I and then mixed to obtain a mixture II . In each of the mixing process mentioned above, the mixing speed was 150 revolutions per minute and the mixing time was 20 minutes. The mixture II was granulated using a twin-screw extruder. After high-temperature melting, screw conveying, extruding, cooling, pelletizing and drying, polyamide-6 masterbatch was obtained. The temperature of each temperature zone of twin-screw extruder respectively were: 220 ℃ in the first section, 230 ℃ in the second section, 250 ℃ in the third section, 250 ℃ in the fourth section, and 260 ℃ in the fifth section.

Comparative example 2

71 parts of polyethylene terephthalate resin and 15 parts of nano zinc oxide were evenly mixed to give a mixture I. 3 parts of liquid paraffin was subsequently added to the mixture I and then mixed to obtain a mixture II. And then 10 part of nano zinc oxide was added to the mixture II and further mixed evenly to produce a mixture III . Finally, 1 part of liquid paraffin was added to the mixture III and then mixed evenly to give a mixture IV . In each of the mixing process mentioned above, the mixing speed was 150 revolutions per minute and the mixing time was 20 minutes. The mixture IV was granulated using a twin-screw extruder. After high-temperature melting, screw conveying, extruding, cooling, pelletizing and drying, polyethylene terephthalate masterbatch was obtained. The temperature of each temperature zone of twin-screw extruder respectively were: 262 ℃ in the first section, 265 ℃ in the second section, 265 ℃ in the third section, 265 ℃ in the fourth section, and 270 ℃ in the fifth section.

During the mixing process of comparative example 1 and comparative example 2, serious dust flying occurred. As shown in Fig. 6 and Fig. 7, the antibacterial agent presents in the form of aggregates and is poorly dispersed in the antibacterial masterbatches obtained from comparative example 1 and comparative example 2.

Example 5: polyester antibacterial yarn and its preparation

Polyethylene terephthalate (PET) resin and nano zinc oxide were dried in a drying equipment before use. The raw material composition of the polyester antibacterial yarn includes: in parts by mass, 99.76 parts of polyethylene terephthalate resin, 0.2 part of nano zinc oxide and 0.04 part of anhydrous glycerol. 99.76 parts of polyethylene terephthalate resin and 0.04 part of anhydrous glycerol were evenly mixed to give a mixture I. 0.2 part of nano zinc oxide was subsequently added to the mixture I and then mixed to obtain a mixture II. In each of the mixing process mentioned above, the mixing speed was 150 revolutions per minute and the mixing time was 20 minutes. The mixture II was prepared into an antibacterial yarn with yarn type POY300D/288F through a conventional yarn production equipment.

Example 6: polyester antibacterial yarn and its preparation

Example 6 is basically the same as example 5, except that the raw material composition of the polyester antibacterial yarn includes: in parts by mass, 99 parts of polyethylene terephthalate resin, 0.6 part of nano zinc oxide and 0.4 part of anhydrous glycerol. 99 parts of polyethylene terephthalate resin and 0.4 part of anhydrous glycerol were evenly mixed to give a mixture I. 0.6 part of nano zinc oxide was subsequently added to the mixture I and then mixed to obtain a mixture II. In each of the mixing process mentioned above, the mixing speed was 150 revolutions per minute and the mixing time was 20 minutes. The mixture II was prepared into an antibacterial yarn with yarn type POY300D/288F through a conventional yarn production equipment.

Example 7: polyamide antibacterial yarn and its preparation

Polyamide-6 (PA6) resin, nano zinc oxide and polyethylene wax were dried in a drying equipment before use. The raw material composition of the polyamide antibacterial yarn includes: in parts by mass, 97 parts of polyamide-6 resin, 1 part of nano zinc oxide, 1 part of polyethylene wax and 1 part of liquid paraffin. Wherein, the nano zinc oxide is surface modified by a silane coupling agent KH570 (CAS number is 2530-85-0) , and the mass ratio of the silane coupling agent to the nano zinc oxide surface is 3%. 97 parts of polyamide-6 resin, 1 part of polyethylene wax and 1 part of liquid paraffin were evenly mixed in a mixing equipment to give a mixture I. 1 part of nano zinc oxide was added to the mixture I and then mixed to obtain a mixture II. In each of the mixing process mentioned above, the mixing speed was 150 revolutions per minute and the mixing time was 20 minutes. The mixture II was prepared into an antibacterial yarn with yarn type FDY140D/136F using a conventional yarn production equipment.

FIG. 8 to FIG. 10 are respectively sectional scanning electron microscope images of the antibacterial yarns obtained from examples 5-7. It can be seen that the inorganic antibacterial agent is evenly distributed on the surface and inside of the yarn, and the dispersion size of the inorganic antibacterial agent is about 200 nm.

According to National Standard GB/T 14337-2008 “testing method for tensile properties of man-made staple fibers” , the breaking strength of the antibacterial yarns obtained from examples 5-7 were tested and compared with comparative yarns of the same type (without an antibacterial agent) . The test results are shown in Fig. 15 (i.e., Table 2) .

It can be seen from Table 2 that the breaking strength of the antibacterial yarns obtained from examples 5-7 do not show a significantly decrease compared with that of the comparative yarns without an antibacterial agent.

The antibacterial yarns obtained from examples 5-7 and the ordinary yarns (i.e., comparative yarns) with corresponding type at a certain mass ratio, were prepared into an antibacterial fabric with a weight of 155 g/m ² by means of the conventional fabric production process. According to National Standard GB/T 20944.2-2007 “Textiles-Evaluation for antibacterial activity-Part 2: Absorption method” , the antibacterial rate of the antibacterial fabric against Escherichia coli and Staphylococcus aureus was tested. The test results are shown in Fig. 16 (i.e., Table 3) .

It can be seen from Table 3 that the antibacterial fabrics prepared using the antibacterial yarns obtained from examples 5-7 have an antibacterial rate greater than 99%, and belongs to highly efficient antibacterial fabrics.

According to Japanese Industrial Standard JIS L1902: 2015 “Textiles-Determination of antibacterial activity and efficacy of textile products” , the antibacterial activity of the antibacterial fabric before and after washing were tested against Staphylococcus aureus and Pneumoniae by the biological bacteria liquid absorption method. Wherein, the antibacterial fabric is prepared from antibacterial FDY140D/136F yarn obtained from example 7 and ordinary FDY140D136F yarn (without an antibacterial agent) . The test results are shown in Fig. 17 (i.e., Table 4) .

It can be seen from Table 4 that, after 30 times of washing, the both antibacterial fabrics have an antibacterial activity higher than the standard value of 2.2 against Staphylococcus aureus and Pneumoniae, indicating that the antibacterial fabrics have excellent antibacterial properties.

Example 8: polypropylene antibacterial masterbatch and its preparation

Polypropylene (PP) resin, nano zinc oxide and oxidized polyethylene wax (with a melting point of about 110 ℃) were dried in a drying equipment before use. The raw material of the polypropylene antibacterial masterbatch includes: in parts by mass, 92 parts of polypropylene resin, 5 parts of nano zinc oxide, 2 parts of oxidized polyethylene wax and 1 part of anhydrous glycerol.

Oxidized polyethylene wax and anhydrous glycerol were evenly mixed to give a mixture I. Nano zinc oxide was subsequently added to the mixture I and then mixed to obtain a mixture II. In each of the mixing process mentioned above, the mixing speed was 150 revolutions per minute and the mixing time was 20 minutes. The mixture II was put into a double-screw extruder, and a first granulation treatment was accomplished after high temperature melting, screw conveying, extruding, cooling, pelleting and drying. The temperature of the first granulation treatment ranged from 110 to 170 ℃. The particle obtained from the first granulation treatment (i.e., a mixture of the dispersant, binder and inorganic antibacterial agent) and polypropylene resin were put into the double-screw extruder, and a second granulation treatment was accomplished after high temperature melting, screw conveying, extruding, cooling, pelleting and drying, to obtain the polypropylene antibacterial masterbatch. The temperature of the second granulation treatment ranged from 160 to 260 ℃.

Example 9: polypropylene antibacterial masterbatch and its preparation

Example 9 is basically the same as example 8, except that the raw material composition of the polypropylene antibacterial masterbatch includes: in parts by mass, 78 parts of polypropylene (PP) resin, 15 parts of nano titanium dioxide (with an average particle size of 2 μm) , 5 parts of oxidized polyethylene wax, and 2 parts of liquid paraffin.

Example 10: low-density polyethylene antibacterial masterbatch and its preparation

Example 10 is basically the same as example 8, except that the raw material composition of the low-density polyethylene antibacterial masterbatch includes: in parts by mass, 56 parts of low-density polyethylene resin, 30 parts of nano zinc oxide, 10 parts of polyethylene wax, and 4 parts of liquid paraffin. Wherein, the nano zinc oxide is surface modified by a silane coupling agent KH570 (CAS number is 2530-85-0) , and the mass ratio of the silane coupling agent to the nano zinc oxide is 3%. During the preparation of the low-density polyethylene antibacterial masterbatch, the temperature of the first granulation treatment ranged from 160 to 190 ℃.

The antibacterial masterbatches prepared from examples 8-10 were respectively prepared into plastic sheets with the same method as in example 1. The mass fraction of the inorganic antibacterial agent of the plastic sheets is 1%. According to National Standard GB/T 31402-2015 “Plastics-Measurement of antibacterial activity on plastics surfaces” , the antibacterial rate of the plastic sheets against Escherichia coli and Staphylococcus aureus was tested. The test results are shown in Fig. 18 (i.e., Table 5) .

It can be seen from Table 5 that, the antibacterial rate of the polyolefin masterbatch can be increased to 99%or more, indicating that the present application also provides an preparation method of antibacterial masterbatch suitable for completely hydrophobic matrix resin, especially polyolefin matrix resin.

Claims

A preparation method of an antibacterial masterbatch containing a highly dispersed inorganic antibacterial agent, wherein the preparation method comprising the following steps:

performing a primary mixing treatment on the raw material including a polymer matrix and a binder to give a polymer matrix with at least part of the surface spreading the binder;

subjecting an inorganic antibacterial agent and the polymer matrix with at least part of the surface spreading the binder to a second mixing treatment to give a polymer matrix with the inorganic antibacterial agent adhered to the surface thereof; and

granulating the polymer matrix with the inorganic antibacterial agent adhered to the surface thereof into an antibacterial masterbatch.
The preparation method of claim 1, wherein the mass ratio of the polymer matrix and the binder is (60 to 90) : (0.5 to 5) .
The preparation method of claim 1, wherein the mass ratio of the polymer matrix and the inorganic antibacterial agent is (60 to 90) : (1 to 30) .
The preparation method of claim 1, wherein the binder is selected from a group consisting of polyol, polymeric alcohol, polyester polyol and hydrocarbon mixture, and the hydrocarbon mixture has a carbon atom number between 12 and 36.
The preparation method of claim 1, wherein the inorganic antibacterial agent is selected from a group consisting of CuO, ZnO, TiO2, SiO2, Al2O3, WO3, ZrO2, V2O3, SnO2, FeO and Fe3O4, and the particle size of the inorganic antibacterial agent is 25 nm to 2 μm.
The preparation method of claim 1, wherein the preparation method comprising the following steps:

performing a primary mixing treatment on the raw material including a polymer matrix and a portion of a binder to give a polymer matrix with at least part of the surface spreading the binder;

subjecting the polymer matrix with at least part of the surface spreading the binder, and a portion of an inorganic antibacterial agent to a second mixing treatment to give a polymer matrix with the inorganic antibacterial agent adhered to the surface thereof;

performing a third mixing treatment on the polymer matrix with the inorganic antibacterial agent adhered to the surface thereof and the rest of the binder to obtain a polymer matrix with the binder re-spread on the surface;

subjecting the rest of the inorganic antibacterial agent and the polymer matrix with the binder re-spread on the surface to a fourth mixing treatment to obtain a polymer matrix on which the inorganic antibacterial agent is re-adhered to the surface; and

granulating the polymer matrix on which the inorganic antibacterial agent is re-adhered to the surface into an antibacterial masterbatch.
The preparation method of claim 6, wherein the binder for the primary mixing treatment is 20%to 80%of the total mass of the binder, and the inorganic antibacterial agent for the second mixing treatment is 25%to 80%of the total mass of the inorganic antibacterial agent.
The preparation method of claim 1, wherein the primary mixing treatment and/or second mixing treatment has a mixing speed of 30 to 3000 revolutions per minute and a mixing time of 1 to 60 minutes.
The preparation method of claim 1, in addition to the polymer matrix and the binder, the raw material for the primary mixing treatment also includes a dispersant, wherein the mass ratio of the polymer matrix to the dispersant is (60 to 90) : (0 to 5) .
An antibacterial masterbatch containing a highly dispersed inorganic antibacterial agent obtained from the preparation method of any one of claims 1 to 9.
A preparation method of an antibacterial yarn without significantly reducing the breaking strength of yarn, wherein the preparation method comprising the following steps:

performing a primary mixing treatment on the raw material including a polymer matrix and a binder to give a polymer matrix with at least part of the surface spreading the binder;

subjecting an inorganic antibacterial agent and the polymer matrix with at least part of the surface spreading the binder to a second mixing treatment to give a polymer matrix with the inorganic antibacterial agent adhered to the surface thereof; and

spinning the polymer matrix with the inorganic antibacterial agent adhered to the surface thereof into an antibacterial yarn.
The preparation method of claim 11, wherein the inorganic antibacterial agent has a dispersion size of 300 nm or less in the antibacterial yarn.
The preparation method of claim 11, wherein the preparation method of the antibacterial yarn does not comprise a step of preparing an antibacterial masterbatch using raw material including a polymer matrix, a binder and an inorganic antibacterial agent prior to spinning.
The preparation method of claim 11, wherein the polymer matrix is polyester polymer and/or polyamide polymer.
A preparation method of a polyolefin antibacterial masterbatch, wherein the preparation method comprising the following steps:

mixing a dispersant and a binder to obtain a first mixture in which the binder is evenly spread on the surface of the dispersant;

adding an inorganic antibacterial agent to the first mixture, and continue mixing to obtain a second mixture in which the inorganic antibacterial agent is uniformly adhered to the surface of the dispersant;

subjecting the second mixture to a first granulation treatment;

subjecting polyolefin matrix and particle obtained from the first granulation treatment to a second granulation treatment to obtain a polyolefin antibacterial master batch.