An antibacterial high-transparency and low-haze BOPET film

Abstract

The present invention provides an antibacterial high-transmittance low-fog BOPET film, which relates to the technical field of polyester films, and comprises an A layer, a B layer and a C layer arranged in sequence; the A layer is an antibacterial functional layer; the B layer is a core layer; the C layer is a low-fog layer; wherein the A layer comprises the following components by weight: 85-90 parts of silica sol-modified antibacterial slices; and 10-15 parts of a first opening agent. The antibacterial high-transmittance low-fog BOPET film provided by the present invention, by selecting silica sol-modified antibacterial slices, does not affect the optical properties of the film material while playing the role of blocking and killing bacteria and viruses, thereby being able to take into account both the antibacterial and optical properties of the film material.

Description

Technical Field

[0001] The invention relates to the technical field of polyester films, in particular to an antibacterial high-transmittance and low-fog BOPET film. Background Art

[0002] Polyethylene terephthalate (PET) has become one of the most important polyester materials due to its good processing properties and mechanical strength. Its biaxially stretched film has been widely used in packaging, electronic insulation, photovoltaics, medical and other fields.

[0003] Medical isolation masks are usually used to prevent medical staff from coming into contact with pollutants during consultations, diagnosis and examinations; medical isolation masks will not only be used by medical staff, but more people, especially families with elderly people and children, will have a large demand for purchasing them. The main material of medical isolation masks is PET, with a thickness of 200-300μm. It is not only required to have good optical and mechanical properties, be able to curl, and ensure a clear field of vision, but also have high requirements for antibacterial effects.

[0004] Traditional polyester films usually improve their antibacterial properties by adding antibacterial agents, but the addition of antibacterial agents will cause the clarity of the film to deteriorate, making it difficult to balance the antibacterial and optical properties of the film, and cannot meet the current use requirements of medical isolation masks. Summary of the invention

[0005] The technical problem to be solved by the present invention is: in order to solve the problem that it is difficult for polyester films in the prior art to have both antibacterial properties and optical properties, the present invention provides an antibacterial high-transmittance and low-fog BOPET film. The BOPET film introduces silica sol-modified antibacterial slices to improve the antibacterial properties without affecting the light transmittance of the film material, thereby solving the problem that it is difficult for polyester films in the prior art to have both antibacterial properties and optical properties.

[0006] The technical solution adopted by the present invention to solve its technical problem is:

[0007] An antibacterial high-transmittance low-fog BOPET film, comprising an A layer, a B layer and a C layer arranged in sequence; the A layer is an antibacterial functional layer; the B layer is a core layer; the C layer is a low-fog layer;

[0008] The A layer comprises the following components in parts by weight:

[0009] 85-90 pieces of silica sol modified antibacterial slices;

[0010] The first opening agent is 10-15 parts.

[0011] Optionally, the silica sol modified antibacterial slice is prepared according to the following method:

[0012] After mixing and stirring anhydrous ethanol and silica sol, an antibacterial agent and a titanate coupling agent are added, and then stirred. It is dried under vacuum in an oven at 70 - 80 °C. After a large amount of powder precipitates, the temperature is raised to 150 °C for drying to obtain silica sol-modified antibacterial powder; the silica sol-modified antibacterial powder is uniformly mixed with a stabilizer, and is melted, extruded, and granulated with bright polyester chips in a blender to obtain the silica sol-modified antibacterial chips.

[0013] Optionally, the antibacterial agent is a quaternary ammonium salt antibacterial agent.

[0014] Optionally, the quaternary ammonium salt antibacterial agent is selected from at least one of tetradecyl trimethyl ammonium bromide, cetyl trimethyl ammonium bromide, octadecyl trimethyl ammonium bromide, and octadecyl dimethyl benzyl ammonium bromide.

[0015] Optionally, the stabilizer is a phosphite stabilizer.

[0016] Optionally, the mass ratio of the anhydrous ethanol to the silica sol is 4:1; the mass ratio of the antibacterial agent to the silica sol is 1:1; the mass ratio of the titanate coupling agent to the silica sol is 1:100; the mass ratio of the silica sol-modified antibacterial powder to the stabilizer and the bright polyester chips is 1:0.5:98.5.

[0017] Optionally, the C layer includes a C layer substrate and an antireflection coating coated on the surface of the C layer substrate;

[0018] The C layer substrate, by weight, comprises the following components:

[0019] Bright polyester chips 90 - 95 parts;

[0020] Second opening agent 5 - 10 parts;

[0021] The antireflection coating, by weight, comprises the following components:

[0022]

[0023] Optionally, the inorganic antireflection component is selected from at least one of nanoscale silica sol, nanoscale magnesium fluoride, nanoscale calcium fluoride, and nanoscale zinc sulfide.

[0024] Optionally, the acrylic monomer includes 2 - hydroxyethyl acrylate and at least one of acrylic acid, methacrylic acid, methyl methacrylate, ethyl acrylate, and butyl acrylate.

[0025] Optionally, the emulsifier is sodium dodecyl sulfonate; the leveling agent is a silicone leveling agent; the initiator is potassium persulfate or ammonium persulfate.

[0026] The beneficial effects of the present invention are:

[0027] The antibacterial high-transparency and low-haze BOPET film provided by the present invention selects silica sol-modified antibacterial chips, which can play a role in blocking and killing bacteria and viruses while not affecting the optical properties of the film material, so that the antibacterial properties and optical properties of the film material can be taken into account. Specific Embodiments

[0028] The present invention will now be further described in detail. The embodiments described below are exemplary and are intended to explain the present invention and should not be construed as limiting the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts fall within the scope of protection of the present invention.

[0029] In the description of the present invention, it should be understood that the terms "first" and "second" are only used for simplified description and cannot be construed as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, the features defined as "first" and "second" may explicitly or implicitly include one or more of these features. In the description of the present invention, "a plurality" means two or more unless otherwise specifically defined.

[0030] To solve the problem that it is difficult for polyester films in the prior art to balance antibacterial properties and optical properties, the present invention provides an antibacterial high-transparency and low-haze BOPET film, which includes an A layer, a B layer, and a C layer arranged in sequence; wherein the A layer is an antibacterial functional layer; the B layer is a core layer; the C layer is a low-haze layer; both the B layer and the C layer can select existing core layers and low-haze layers suitable for medical isolation masks; the A layer in the present invention, by weight, includes the following components:

[0031] 85-90 parts of silica sol-modified antibacterial chips;

[0032] 10-15 parts of a first anti-blocking agent.

[0033] The antibacterial high-transparency and low-haze BOPET film provided by the present invention selects silica sol-modified antibacterial chips, which can play a role in blocking and killing bacteria and viruses while not affecting the optical properties of the film material, so that the antibacterial properties and optical properties of the film material can be taken into account.

[0034] In addition, since medical isolation masks are not limited to use by medical staff at present and the demand of the general public is increasing, in addition to having good antibacterial properties, the requirements for the service life of isolation masks are also getting higher and higher; traditional film materials directly adding antibacterial agents are prone to yellowing during use, which affects the clarity and aesthetics of the field of vision and has a short service life; while the present invention can improve antibacterial properties by adding silica sol-modified antibacterial chips and can also avoid yellowing caused by directly adding antibacterial agents, thereby helping to extend its service life.

[0035] In order to take into account the antibacterial properties, optical properties and mechanical properties of the antibacterial high-transmittance and low-fog BOPET film, the present invention preferably has a thickness range of 200-300 μm, and further preferably comprises 5-7.5 parts of layer A, 85-90 parts of layer B, and 5-7.5 parts of layer C in terms of weight.

[0036] The preferred silica sol modified antibacterial slice of the present invention is prepared according to the following method:

[0037] After mixing anhydrous ethanol and silica sol, an antibacterial agent and a titanate coupling agent are added, stirred, and vacuum dried in an oven at 70-80°C. After a large amount of powder is precipitated, the temperature is raised to 150°C for drying to obtain silica sol-modified antibacterial powder; the silica sol-modified antibacterial powder is evenly mixed with a stabilizer, and melted, extruded, and granulated with a Dayouguang slice in a blender to obtain a silica sol-modified antibacterial slice.

[0038] The preferred antibacterial agent of the present invention is a quaternary ammonium salt antibacterial agent, and further preferably the quaternary ammonium salt antibacterial agent is selected from at least one of tetradecyl trimethyl ammonium bromide, hexadecyl trimethyl ammonium bromide, octadecyl trimethyl ammonium bromide, and octadecyl dimethyl benzyl ammonium bromide; the preferred stabilizer is a phosphite stabilizer, such as one or more of bisphenol A phosphite, pentaerythritol diphosphite, or tetraisodecyl bisphenol A diphosphite; specifically, the preferred stabilizer of the present invention is bisphenol A phosphite.

[0039] In order to take into account both antibacterial properties and optical properties, the present invention preferably has a mass ratio of anhydrous ethanol to silica sol of 4:1; a mass ratio of antibacterial agent to silica sol of 1:1; a mass ratio of titanate coupling agent to silica sol of 1:100; a mass ratio of silica sol-modified antibacterial powder to stabilizer and optical slice of 1:0.5:98.5; the characteristic viscosity range of the silica sol-modified antibacterial slice of the present invention is 0.6-0.7dL / g.

[0040] In order to take into account the antibacterial property, optical property and mechanical property of the membrane material, the present invention preferably comprises 100% glossy slices in the B layer.

[0041] In order to further improve the optical properties of the film material, the present invention preferably comprises a C layer substrate and an anti-reflection coating applied on the surface of the C layer substrate; wherein the C layer substrate comprises the following components in parts by weight:

[0042] 90-95 large and shiny slices;

[0043] 5-10 parts of the second opening agent;

[0044] The antireflective coating comprises the following components in parts by weight:

[0045]

[0046]

[0047] It should be noted that the first anti-blocking agent and the second anti-blocking agent in the present invention are only named for the convenience of distinction, and do not represent the difference in composition between the two; preferably, both the first anti-blocking agent and the second anti-blocking agent in the present invention are selected from at least one of silicon-based anti-blocking agents, barium-based anti-blocking agents, and calcium-based anti-blocking agents; the first anti-blocking agent and the second anti-blocking agent may be the same or different.

[0048] The anti-reflection coating can be coated by an on-line coating process. The construction position is between longitudinal stretching and transverse stretching. The coating thickness is between 0.5 - 2 μm, and it is only coated on the surface of layer C.

[0049] By coating this anti-reflection coating, while improving the optical performance, it also helps to improve the antibacterial performance.

[0050] Preferably, the inorganic anti-reflection component in the present invention is selected from at least one of nano-sized silica sol, nano-sized magnesium fluoride, nano-sized calcium fluoride, and nano-sized zinc sulfide, and further preferably, the inorganic particle size of the inorganic anti-reflection component is between 20 - 200 nm.

[0051] Preferably, the acrylic monomers in the present invention include hydroxyethyl acrylate, and at least one of acrylic acid, methacrylic acid, methyl methacrylate, ethyl acrylate, and butyl acrylate; that is, the acrylic monomers in the present invention, in addition to hydroxyethyl acrylate, also include at least one of acrylic acid, methacrylic acid, methyl methacrylate, ethyl acrylate, and butyl acrylate; and further preferably, hydroxyethyl acrylate accounts for 10% of the total mass of the acrylic monomers to enhance the adhesion between the anti-reflection coating and BOPET.

[0052] Specifically, preferably, the emulsifier in the present invention is sodium dodecyl sulfate; the leveling agent is a silicone-based leveling agent; the initiator is potassium persulfate or ammonium persulfate.

[0053] The anti-reflection coating liquid used for the anti-reflection coating is prepared according to the following method: Add deionized water and emulsifier into the reaction kettle, stir at 30 - 40 °C for 20 - 30 min, then add acrylic monomers, and raise the temperature to 50 - 60 °C, continue to stir for 30 min until the emulsion is evenly dispersed; then add the initiator, and raise the temperature to 70 - 80 °C, react for 4 - 6 h under continuous stirring until the emulsion shows a light blue color; then cool down to 30 - 40 °C, add the inorganic anti-reflection component and the leveling agent, and continue to stir for 30 - 50 minutes to obtain the anti-reflection coating liquid required for the high light transmittance coating.

[0054] The antibacterial, highly transparent and low haze BOPET film provided by the present invention adopts an ABC three-layer structure, is extruded from a die head by a melt co-extrusion process, and undergoes processes such as sheet casting, longitudinal stretching, coating, transverse stretching, winding, and slitting to obtain the product; the thickness of the product film is 200 - 300 μm, the light transmittance is above 90%, the haze is less than 2%, and it has antibacterial effects. The temperature of the extrusion machine in the above-mentioned melt co-extrusion section is controlled between 265 - 280 °C, and the temperature of the die head is controlled between 280 - 290 °C. In the above-mentioned longitudinal stretching section, the stretching temperature is controlled at 70 - 80 °C, and the stretching ratio is between 2.8 - 3.4; in the transverse stretching section, the stretching temperature is controlled between 110 - 130 °C, the stretching ratio is between 3.0 - 4.0, and the temperature of the setting section is controlled between 220 - 240 °C.

[0055] The BOPET film provided by the present invention can be used for medical isolation masks, adding highly efficient antibacterial components to play a role in blocking and killing bacteria and viruses, and solving the influence of traditional antibacterial agent addition on the clarity of materials and the resulting slight yellowing through the modification of the antibacterial agent. At the same time, the light transmittance of the film material is further improved, and the haze is reduced, enabling the wearer to obtain a clearer vision.

[0056] To make the above objects, features, and advantages of the present invention more obvious and understandable, the following detailed description of the specific embodiments of the present invention is provided.

[0057] In the case of no special instructions, the leveling agent in each embodiment and comparative example of the present invention is BYK - 310 of BYK Chemie.

[0058] Example 1

[0059] Preparation of the anti-reflection coating:

[0060] The formula of the anti-reflection coating solution (calculated based on a total of 100 parts by weight) is: 36 parts of methacrylic acid, 4 parts of 2-hydroxyethyl acrylate, 5 parts of nano-silica sol, 0.9 part of sodium dodecyl sulfate, 0.3 part of potassium persulfate, 0.3 part of silicone leveling agent, and the rest is made up with deionized water.

[0061] Add deionized water and sodium dodecyl sulfate into the reaction kettle, stir at 40 °C for 30 min, then add methacrylic acid and 2-hydroxyethyl acrylate, and raise the temperature to 50 °C, continue stirring for 30 min until the emulsion is evenly dispersed. Subsequently, add potassium persulfate, and raise the temperature to 80 °C, and react for 5 h under continuous stirring until the emulsion shows a light blue color. Then cool down to 30 °C, add nano-silica sol and leveling agent, and continue stirring for 40 minutes to obtain the anti-reflection coating solution.

[0062] Preparation of the antibacterial masterbatch:

[0063] Add absolute ethanol and silica sol into the reactor in proportion, with the mass ratio of the two being about 4:1. After stirring for 10 min, add cetyltrimethylammonium bromide equal in amount to the silica sol, and add 1% (by mass of the silica sol) titanate coupling agent. Continue stirring for 30 min, and then dry under vacuum in an oven at 70 - 80 °C. After a large amount of powder precipitates, raise the temperature to 150 °C and dry for 10 h for standby, thus obtaining the quaternary ammonium salt antibacterial powder modified with silica sol.

[0064] Mix 1% (by mass) of the modified antibacterial powder and 0.5% (by mass) of the stabilizer evenly, and then melt, extrude, and pelletize them with 98.5% (by mass) of bright polyester chips in a blender to obtain antibacterial chips with an intrinsic viscosity of 0.6 - 0.7 dL / g.

[0065] BOPET film processing:

[0066] After the raw materials are sucked into the silo and dried, they enter the main and auxiliary extruders. Among them, the No. 1 auxiliary extruder is for layer A, the No. 2 auxiliary extruder is for layer C, and the main extruder is for layer B. The metering pumps of the No. 1 auxiliary extruder (layer A), the main extruder (layer B), and the No. 2 auxiliary extruder (layer C) extrude at a mass ratio of 5:90:5 respectively. Among them, layer A is the antibacterial functional layer, which is composed of antibacterial chips and a silicon-based anti-blocking agent, with the proportion of the two being 85% and 15% respectively; layer B is the core layer, which is composed of 100% bright polyester chips; layer C is the low haze layer, which is composed of bright polyester chips and a silicon-based anti-blocking agent, with the proportion of the two being 95% and 5% respectively. The temperature of the extrusion section is controlled at 265 - 280 °C, and the die head temperature is at 280 - 290 °C. The melt is extruded through a three-layer co-extrusion die head, then cast into a sheet by a cold roll and enters the longitudinal stretching area. The stretching temperature is set at 75 °C, and the stretching ratio is set at 3.0.

[0067] The on-line coating equipment is located in front of the entrance of the transverse stretching section, and a single-sided antireflection coating liquid is coated on the surface of layer C, with the coating thickness being 2 μm.

[0068] After the antireflection coating is coated, the BOPET film enters the transverse stretching area and passes through four areas of preheating, stretching, shaping, and cooling in sequence, thus obtaining a high-transparency, low-haze antibacterial BOPET film. Among them, the temperature of the stretching section is set at 110 - 130 °C, the temperature of the shaping section is set at 220 - 240 °C, and the stretching ratio is set at 4.0.

[0069] After passing through processes such as flattening, antistatic treatment, and winding, an antibacterial high-transparency, low-haze BOPET film with a thickness of 200 μm is obtained.

[0070] Example 2

[0071] Preparation of the antireflection coating:

[0072] The formula of the anti-reflection coating solution (based on 100 parts in total) is as follows: 36 parts of methacrylic acid, 4 parts of hydroxyethyl acrylate, 5 parts of nano-scale magnesium fluoride, 0.9 parts of sodium dodecyl sulfonate, 0.3 parts of potassium persulfate, 0.3 parts of silicone leveling agent, and the rest is made up with deionized water.

[0073] Add deionized water and sodium dodecyl sulfonate into the reaction kettle, stir at 40 °C for 30 min, then add methacrylic acid and hydroxyethyl acrylate, and raise the temperature to 50 °C, continue to stir for 30 min until the emulsion is evenly dispersed. Subsequently, add potassium persulfate, and raise the temperature to 80 °C, react under continuous stirring for 5 h until the emulsion shows a light blue color. Then cool down to 30 °C, add nano-scale magnesium fluoride and leveling agent, and continue to stir for 40 minutes to obtain the anti-reflection coating.

[0074] Preparation of antibacterial slices:

[0075] Add absolute ethanol and silica sol into the reaction kettle in proportion, and the mass ratio of the two is about 4:1. After stirring for 10 min, add cetyltrimethylammonium bromide equal to the amount of silica sol, and add 1% of titanate coupling agent based on the mass of silica sol. Continue to stir for 30 min, and vacuum dry in an oven at 70 - 80 °C. After a large amount of powder precipitates, raise the temperature to 150 °C and dry for 10 h for standby, then the quaternary ammonium salt antibacterial powder modified by silica sol is obtained.

[0076] Mix 1% of the modified antibacterial powder and 0.5% of the stabilizer evenly, and melt, extrude, and granulate with 98.5% of the bright polyester chips in a co-mixer to obtain antibacterial slices with an intrinsic viscosity of 0.6 - 0.7 dL / g.

[0077] BOPET film processing:

[0078] After the raw materials are inhaled into the silo and dried, they enter the main and auxiliary extruders. The No. 1 auxiliary extruder is layer A, the No. 2 auxiliary extruder is layer C, and the main extruder is layer B. The metering pumps of the No. 1 auxiliary extruder (layer A), the main extruder (layer B), and the No. 2 auxiliary extruder (layer C) are extruded according to a mass ratio of 5:90:5 respectively. Among them, layer A is the antibacterial functional layer, which consists of antibacterial slices and silica-based opening agent, and their proportions are 85% and 15% respectively; layer B is the core layer, which consists of 100% bright polyester chips; layer C is the low haze layer, which consists of bright polyester chips and silica-based opening agent, and their proportions are 95% and 5% respectively. The temperature of the extrusion section is controlled at 265 - 280 °C, and the die head temperature is at 280 - 290 °C. The melt is extruded by a three-layer co-extrusion die head, then cast into a sheet by a cold roll and enters the longitudinal stretching area. The stretching temperature is set at 75 °C, and the stretching ratio is set at 3.0.

[0079] The on-line coating equipment is located in front of the transverse stretching entrance, coated on one side, coated on the surface of layer C, and the coating thickness is 2 microns.

[0080] After the antireflection coating is applied, the BOPET film enters the transverse stretching area and passes through four areas: preheating, stretching, shaping, and cooling, and then the high-transparency, low-haze, antibacterial BOPET film is obtained. Among them, the temperature of the stretching section is set at 110 - 130 °C, the temperature of the shaping section is set at 220 - 240 °C, and the stretching ratio is set at 4.0.

[0081] After processes such as flattening, static elimination, and winding, an antibacterial, high-transparency, low-haze BOPET film with a thickness of 200 μm is obtained.

[0082] Example 3

[0083] Preparation of the antireflection coating:

[0084] The formula of the antireflection coating solution (based on a total of 100 parts by weight) is as follows: 36 parts of methacrylic acid, 4 parts of hydroxyethyl acrylate, 2 parts of nanoscale silica sol, 0.5 part of sodium dodecyl sulfate, 0.1 part of potassium persulfate, 0.2 part of silicone leveling agent, and the rest is made up with deionized water.

[0085] Add deionized water and sodium dodecyl sulfate into the reaction kettle, stir at 40 °C for 30 min, then add methacrylic acid and hydroxyethyl acrylate, and raise the temperature to 50 °C, continue to stir for 30 min until the emulsion is evenly dispersed. Subsequently, add potassium persulfate, and raise the temperature to 80 °C, react for 5 h under continuous stirring until the emulsion shows a light blue color. Then cool down to 30 °C, add nanoscale silica sol and leveling agent, and continue to stir for 40 minutes to obtain the antireflection coating solution.

[0086] Preparation of the antibacterial chips:

[0087] Add absolute ethanol and silica sol into the reaction kettle in proportion, with a mass ratio of about 4:1, stir for 10 min, then add cetyltrimethylammonium bromide equal to the amount of silica sol, and add 1% of titanate coupling agent based on the mass of silica sol, continue to stir for 30 min, and dry under vacuum in an oven at 70 - 80 °C. After a large amount of powder precipitates, raise the temperature to 150 °C and dry for 10 h for standby, and then the quaternary ammonium salt antibacterial powder modified by silica sol is obtained.

[0088] Mix 1% by mass of the modified antibacterial powder and 0.5% by mass of the stabilizer evenly, and melt, extrude, and granulate them with 98.5% by mass of the bright polyester chips in a co-mixer to obtain antibacterial chips with an intrinsic viscosity of 0.6 - 0.7 dL / g.

[0089] Processing of the BOPET film:

[0090] After the raw materials are inhaled into the silo, they are dried and then enter the main and auxiliary extruders. Among them, the No. 1 auxiliary extruder is layer A, the No. 2 auxiliary extruder is layer C, and the main extruder is layer B. The metering pumps of the No. 1 auxiliary extruder (layer A), the main extruder (layer B), and the No. 2 auxiliary extruder (layer C) extrude according to the mass ratio of 7.5:85:7.5 respectively. Among them, layer A is the antibacterial functional layer, which is composed of antibacterial chips and silicon-based opening agents, and the proportion of the two is 90% and 10% respectively; layer B is the core layer, which is composed of 100% bright polyester chips; layer C is the low haze layer, which is composed of bright polyester chips and silicon-based opening agents, and the proportion of the two is 90% and 10% respectively. The temperature of the extrusion section is controlled at 265-280 °C, and the die head temperature is at 280-290 °C. The melt is extruded by a three-layer co-extrusion die head, then cast into a sheet by a cold roll and enters the longitudinal stretching area. The stretching temperature is set at 75 °C, and the stretching ratio is set at 3.0.

[0091] The on-line coating equipment is located in front of the transverse stretching inlet, and a single-sided anti-reflection coating liquid is coated on the surface of layer C, and the coating thickness is 2 microns.

[0092] After the anti-reflection coating is applied, the BOPET film enters the transverse stretching area and passes through four areas: preheating, stretching, shaping and cooling, and then a high-transparency, low-haze and antibacterial BOPET film is obtained. Among them, the temperature of the stretching section is set at 110-130 °C, the temperature of the shaping section is set at 220-240 °C, and the stretching ratio is set at 4.0.

[0093] After passing through processes such as flattening, static elimination and winding, an antibacterial, high-transparency and low-haze BOPET film with a thickness of 200 μm is obtained.

[0094] Example 4

[0095] Preparation of the anti-reflection coating:

[0096] The formula of the anti-reflection coating liquid (calculated based on a total of 100 parts by weight) is: 36 parts of methacrylic acid, 4 parts of hydroxyethyl acrylate, 6 parts of nano-silica sol, 0.7 parts of sodium dodecyl sulfonate, 0.4 parts of potassium persulfate, 0.5 parts of silicone leveling agent, and the rest is made up with deionized water.

[0097] Add deionized water and sodium dodecyl sulfonate into the reaction kettle, stir at 40 °C for 30 min, then add methacrylic acid and hydroxyethyl acrylate, and raise the temperature to 50 °C, and continue to stir for 30 min until the emulsion is evenly dispersed. Subsequently, add potassium persulfate and raise the temperature to 80 °C, and react for 5 h under continuous stirring until the emulsion shows a light blue color. Then cool down to 30 °C, add nano-silica sol and leveling agent, and continue to stir for 40 minutes to obtain the anti-reflection coating liquid.

[0098] Preparation of antibacterial chips:

[0099] Add absolute ethanol and silica sol into the reactor in proportion, and the mass ratio of the two is about 4:1. After stirring for 10 min, add an equal amount of octadecyltrimethylammonium bromide to the silica sol, and add 1% of titanate coupling agent based on the mass of the silica sol. Continue to stir for 30 min, and then vacuum dry in an oven at 70 - 80 °C. After a large amount of powder precipitates, raise the temperature to 150 °C and dry for 10 h for standby, thus obtaining the quaternary ammonium salt antibacterial powder modified by silica sol.

[0100] Mix 1% of the modified antibacterial powder by mass fraction and 0.5% of the stabilizer by mass fraction evenly, and melt, extrude, and granulate with 98.5% of bright polyester chips in a blender to obtain antibacterial chips with an intrinsic viscosity of 0.6 - 0.7 dL / g.

[0101] BOPET film processing:

[0102] After the raw materials are inhaled into the silo and dried, they enter the main and auxiliary extruders. The No. 1 auxiliary extruder is layer A, the No. 2 auxiliary extruder is layer C, and the main extruder is layer B. The metering pumps of the No. 1 auxiliary extruder (layer A), the main extruder (layer B), and the No. 2 auxiliary extruder (layer C) are extruded according to the mass ratio of 6:88:6 respectively. Among them, layer A is the antibacterial functional layer, which consists of antibacterial chips and a silicon-based anti-blocking agent, and their proportions are 85% and 15% respectively; layer B is the core layer, which consists of 100% bright polyester chips; layer C is the low haze layer, which consists of bright polyester chips and a silicon-based anti-blocking agent, and their proportions are 95% and 5% respectively. The temperature of the extrusion section is controlled at 265 - 280 °C, and the die head temperature is at 280 - 290 °C. After the melt is extruded by a three-layer coextrusion die head, it is cast into a film by a cold roll and then enters the longitudinal stretching area. The stretching temperature is set at 75 °C, and the stretching ratio is set at 3.0.

[0103] The on-line coating equipment is located in front of the entrance of the transverse stretching. The antireflective coating liquid is coated on one side and applied to the surface of layer C, and the coating thickness is 2 μm.

[0104] After the antireflective coating is applied, the BOPET film enters the transverse stretching area and passes through four areas of preheating, stretching, shaping, and cooling in sequence, thus obtaining a high-transparency, low-haze antibacterial BOPET film. Among them, the temperature of the stretching section is set at 110 - 130 °C, the temperature of the shaping section is set at 220 - 240 °C, and the stretching ratio is set at 4.0.

[0105] After processes such as flattening, antistatic treatment, and winding, an antibacterial high-transparency, low-haze BOPET film with a thickness of 200 μm is obtained.

[0106] Comparative Example 1

[0107] The processing method of the BOPET film is similar to that of Example 1. The formulations and proportions used in layers A / B / C are the same as those in Example 1. The difference is that no antireflective coating is applied on the surface of layer C.

[0108] Comparative Example 2

[0109] The processing method of the BOPET film is similar to that of Example 1, and an antireflection coating is applied on the surface of the C layer. The difference is that the A layer does not contain antibacterial chip components, but is the same as the C layer in formulation, being bright polyester chips and an opening agent, with proportions of 95% and 5% respectively.

[0110] Comparative Example 3

[0111] The processing method of the BOPET film is similar to that of Example 1, and the formulations and proportions used in the A / B / C layers are the same as those in Example 1. The difference is that the antibacterial component used in the A layer is not modified but directly added, and the addition ratio is the same as that in Example 1, that is, 1% by mass of tetradecyltrimethylammonium bromide is directly added.

[0112] Comparative Example 4

[0113] The processing method of the BOPET film is similar to that of Example 1, and the formulations and proportions used in the A / B / C layers are the same as those in Example 1. The difference is that no antibacterial chip components are added to the A layer, and the proportion is made up by bright polyester chips; no antireflection coating is applied on the surface of the C layer.

[0114] Comparative Example 5

[0115] The processing method of the BOPET film is similar to that of Example 1, and the formulations and proportions used in the A / B / C layers are the same as those in Example 1. The difference is that the antibacterial chips are prepared as follows:

[0116] In a reaction kettle, anhydrous ethanol and tetradecyltrimethylammonium bromide are added in proportion, and the mass ratio of the two is about 4:1. After stirring for 10 min, 1% of titanate coupling agent based on the mass of tetradecyltrimethylammonium bromide is added, and stirring is continued for 30 min. Then, it is vacuum dried in an oven at 70 - 80 °C. After a large amount of powder precipitates, the temperature is raised to 150 °C and dried for 10 h for standby, thus obtaining quaternary ammonium salt antibacterial powder.

[0117] 1% of the antibacterial powder and 0.5% of the stabilizer are mixed evenly, and are melted, extruded, and pelletized with 98.5% by mass of bright polyester chips in a blender to obtain antibacterial chips with an intrinsic viscosity of 0.6 - 0.7 dL / g.

[0118] Comparative Example 6

[0119] The processing method of the BOPET film is similar to that of Example 1, and the formulations and proportions used in the A / B / C layers are the same as those in Example 1. The difference is that the antibacterial chips are prepared as follows:

[0120] Add absolute ethanol and silica sol into the reaction kettle in proportion, and the mass ratio of the two is about 4:1. After stirring for 10 min, add tetradecyl trimethyl ammonium bromide with a mass ratio of 1:2 to the silica sol, and add 1% (by mass of the silica sol) titanate coupling agent. Continue stirring for 30 min, and then dry under vacuum in an oven at 70 - 80 °C. After a large amount of powder precipitates, raise the temperature to 150 °C and dry for 10 h for standby, thus obtaining the silica sol-modified quaternary ammonium salt antibacterial powder.

[0121] Mix 1% (by mass) of the modified antibacterial powder and 0.5% (by mass) of the stabilizer evenly, and melt, extrude, and granulate them with 98.5% (by mass) of bright polyester chips in a blender to obtain antibacterial chips with an intrinsic viscosity of 0.6 - 0.7 dL / g.

[0122] Comparative Example 7

[0123] The processing method of the BOPET film is similar to that of Example 1, and the formulations and proportions used in the A / B / C layers are the same as those in Example 1. The difference lies in the preparation method of the antibacterial chips as follows:

[0124] Add absolute ethanol and silica sol into the reaction kettle in proportion, and the mass ratio of the two is about 4:1. After stirring for 10 min, add tetradecyl trimethyl ammonium bromide with a mass ratio of 2:1 to the silica sol, and add 1% (by mass of the silica sol) titanate coupling agent. Continue stirring for 30 min, and then dry under vacuum in an oven at 70 - 80 °C. After a large amount of powder precipitates, raise the temperature to 150 °C and dry for 10 h for standby, thus obtaining the silica sol-modified quaternary ammonium salt antibacterial powder.

[0125] Mix 1% (by mass) of the modified antibacterial powder and 0.5% (by mass) of the stabilizer evenly, and melt, extrude, and granulate them with 98.5% (by mass) of bright polyester chips in a blender to obtain antibacterial chips with an intrinsic viscosity of 0.6 - 0.7 dL / g.

[0126] Comparative Example 8

[0127] The processing method of the BOPET film is similar to that of Example 1, and the formulations and proportions used in the A / B / C layers are the same as those in Example 1. The difference lies in that the formulation of the anti-reflection coating solution is (calculated based on a total of 100 parts by weight): 40 parts of methacrylic acid, 5 parts of nano-scale silica sol, 0.9 part of sodium dodecyl sulfonate, 0.3 part of potassium persulfate, 0.3 part of silicone leveling agent, and the balance is made up with deionized water.

[0128] Test the performance of the BOPET films prepared in the above examples and comparative examples. The test methods are as follows:

[0129] Haze: Test according to ASTM D1003 standard;

[0130] Light transmittance: Tested according to ASTM D1003 standard;

[0131] Inhibitory rate against Staphylococcus aureus: Tested according to GB / T31402-2015 standard;

[0132] Color difference: Tested according to ASTM E313-2010 standard.

[0133] The test results are shown in Table 1:

[0134] Table 1

[0135]

[0136] From the above data, it can be seen that the BOPET films provided by each embodiment of the present invention all have high light transmittance, low haze, excellent antibacterial effect and excellent yellowing resistance.

[0137] The optical performance of the BOPET film provided by Comparative Example 1 deteriorates significantly, and at the same time, the yellowing performance deteriorates slightly;

[0138] The antibacterial performance of the BOPET film provided by Comparative Example 2 deteriorates significantly;

[0139] Although the antibacterial component added in Comparative Example 3 is the same as that in Example 1, due to lack of modification, the BOPET film provided not only has significantly deteriorated antibacterial performance, but also its optical performance has declined, and it is prone to yellowing;

[0140] The BOPET film provided by Comparative Example 5 was treated with anhydrous ethanol etc., but not modified with silica sol. Its optical performance has significantly declined, but it is slightly better than Comparative Example 3 in which the antibacterial component was directly added without any treatment;

[0141] The antibacterial performance of the BOPET film provided by Comparative Example 6 has improved compared with Example 1, but its optical performance and yellowing resistance have both deteriorated slightly;

[0142] The BOPET film provided by Comparative Example 7 has better optical performance and yellowing resistance than Example 1, but its antibacterial performance has deteriorated significantly;

[0143] The BOPET film provided by Comparative Example 8 did not add 2-hydroxyethyl acrylate, which affected the adhesion of the coating, and thus led to deterioration of the optical performance.

[0144] Taking the ideal embodiments of the present invention as the inspiration, through the above description, relevant staff can completely make various changes and modifications without departing from the technical idea of this invention. The technical scope of this invention is not limited to the content in the specification, and its technical scope must be determined according to the scope of the claims.

Claims

1. An antibacterial high-transparency and low-haze BOPET film, characterized in that, It includes layer A, layer B and layer C arranged in sequence; layer A is an antibacterial functional layer; layer B is a core layer; layer C is a low haze layer; Among them, layer A, by weight, includes the following components: Silica sol modified antibacterial chips 85 - 90 parts; First anti-blocking agent 10 - 15 parts; The silica sol modified antibacterial chips are prepared by the following method: After mixing and stirring anhydrous ethanol and silica sol, add an antibacterial agent and a titanate coupling agent, stir, vacuum dry in an oven at 70 - 80 °C, and after a large amount of powder precipitates, raise the temperature to 150 °C for drying to obtain silica sol modified antibacterial powder; mix the silica sol modified antibacterial powder evenly with a stabilizer, and melt, extrude and pelletize with bright polyester chips in a blender to obtain the silica sol modified antibacterial chips; The antibacterial agent is a quaternary ammonium salt antibacterial agent; The mass ratio of the antibacterial agent to the silica sol is 1:1; The mass ratio of the silica sol modified antibacterial powder to the stabilizer and the bright polyester chips is 1:0.5:98.5; Layer C includes a layer C matrix and an antireflection coating coated on the surface of the layer C matrix; The layer C matrix, by weight, includes the following components: Bright polyester chips 90 - 95 parts; Second anti-blocking agent 5 - 10 parts; The antireflection coating, by weight, includes the following components: Acrylic monomer 40 parts; Inorganic antireflection component 2 - 6 parts; Emulsifier 0.5 - 0.9 part; Leveling agent 0.2 - 0.5 part; Initiator 0.1 - 0.4 part; Deionized water 52 - 57 parts; The acrylic monomer includes hydroxyethyl acrylate and at least one of acrylic acid, methacrylic acid, methyl methacrylate, ethyl acrylate, butyl acrylate; The component of layer B is 100% bright polyester chips.

2. The antibacterial high-transparency and low-haze BOPET film according to claim 1, characterized in that, The quaternary ammonium salt antibacterial agent is selected from at least one of tetradecyl trimethyl ammonium bromide, cetyl trimethyl ammonium bromide, octadecyl trimethyl ammonium bromide, octadecyl dimethyl benzyl ammonium bromide.

3. The antibacterial high-transparency and low-haze BOPET film according to claim 1, wherein, The stabilizer is a phosphite stabilizer.

4. The antibacterial high-transparency and low-haze BOPET film according to claim 1, wherein The mass ratio of the anhydrous ethanol to the silica sol is 4:1; the mass ratio of the titanate coupling agent to the silica sol is 1:

100.

5. The antibacterial high-transparency and low-haze BOPET film according to claim 1, characterized in that, The inorganic antireflection component is selected from at least one of nano-silica sol, nano-magnesium fluoride, nano-calcium fluoride, nano-zinc sulfide.

6. The antibacterial high-transparency and low-haze BOPET film according to claim 1, wherein, The emulsifier is sodium dodecyl sulfate; the leveling agent is an organosilicon leveling agent; the initiator is potassium persulfate or ammonium persulfate.

Images