Slow-release anti-fog high-transparency PET film and preparation method thereof

Abstract

The present application relates to a kind of slow-release anti-fog high-transmission PET film and its preparation method, in turn include: 1) PET base film layer;2) first anti-fog layer, raw material includes: matrix resin A, anti-fog masterbatch A, nucleating agent;3) slow-release layer, raw material includes: matrix resin B, anti-fog masterbatch B;4) second anti-fog layer, raw material includes: PET resin, anti-fog masterbatch C, nucleating agent;Wherein, anti-fog masterbatch A, anti-fog masterbatch B and anti-fog masterbatch C are obtained by anti-fogging agent and ternary polyester mixing granulation;Anti-fog masterbatch A, anti-fog masterbatch B and anti-fog masterbatch C weight respectively account for 5-20% of the total weight of its layer, and the anti-fogging agent content in first anti-fog layer, the anti-fogging agent content in slow-release layer are all greater than the anti-fogging agent content in second anti-fog layer;The high-transmission PET film is prepared by four-layer co-extrusion, thickness is below 100 μm, light transmittance is above 85%, and haze is below 5%.

Description

Technical Field

[0001] This invention belongs to the field of polyester film technology, and particularly relates to a slow-release anti-fogging high-transparency PET film and its preparation method. Background Technology

[0002] Anti-fog films typically utilize nanotechnology to create superhydrophilic / hydrophobic interfaces to prevent water droplets from condensing on the surface, thereby improving transparency. This method is significant in agricultural production because agricultural films play a crucial role in heat preservation, moisture retention, and increasing crop yield. However, traditional agricultural film materials, such as polyethylene, polyvinyl chloride, and EVA, often cause water droplets to condense on the inner wall of the film due to the difference in surface tension with water, especially under conditions of significant temperature and humidity differences between the inside and outside of greenhouses. This reduces the film's transparency and thus affects crop growth and development. To address this issue, researchers have begun to study methods for creating superhydrophilic interfaces on plastic agricultural films. Among these methods, the use of inorganic nanomaterials to imbue the surface with superhydrophilic anti-fog properties has attracted considerable attention. This method can be achieved through simple and low-cost methods such as chemical spraying or impregnation, giving the agricultural film surface superhydrophilic properties, preventing water droplets from condensing on the surface, thereby improving the film's transparency and promoting crop growth and development.

[0003] Furthermore, with the continuous development of technology, the demand for anti-fog films is constantly increasing. Anti-fog films are currently widely used in various fields, including agricultural production, automobiles, construction, and electronics. In the automotive industry, anti-fog films are widely used on automotive glass and headlights. By using films with anti-fog properties, visibility problems caused by fog and water droplets can be significantly reduced, improving driving safety. In the construction industry, anti-fog films are mainly used on windows and glass curtain walls. By using films with anti-fog properties, window fogging caused by indoor and outdoor temperature differences can be reduced, improving the building's lighting performance and visual effect. In the electronics industry, anti-fog films are mainly used on electronic devices such as touchscreens and displays. By using films with anti-fog properties, screen fogging caused by finger touch or environmental changes can be reduced, improving the device's display effect and user experience. With the continuous development of technology, the performance requirements for anti-fog films are constantly increasing, necessitating the development of anti-fog films with higher transparency, longer anti-fog lifespan, and better mechanical properties to meet the needs of different fields.

[0004] Invention CN113927982B discloses a biaxially oriented polyethylene anti-fog film and its preparation method. The anti-fog film sequentially comprises a surface layer I, a core layer, and a surface layer II. The core layer is made from the following raw materials by mass percentage: 3-5% anti-fog masterbatch, 1-2% coated nano-titanium dioxide, and the balance being linear low-density polyethylene. The surface layer is made from the following raw materials by mass percentage: 95-97% linear low-density polyethylene and 3-5% anti-sticking agent. This invention only adds anti-fog masterbatch to the core layer, but the surface layer of the film is mainly composed of polyethylene and lacks an anti-fog agent. Due to the difference in surface tension between polyethylene and water, water droplets easily condense on the inner wall of the film when there is a large difference in temperature and humidity between the inside and outside, causing the food inside the film to become damp, thus limiting the application scenarios of this film.

[0005] Invention CN114561067A discloses a PP plastic anti-fog sheet and its preparation process. The sheet includes an anti-fog sheet and an anti-fog coating applied to its surface. This invention uses a coating process to uniformly transfer an anti-fog liquid onto the surface of the PP sheet. The PP sheet coated with the anti-fog liquid is then baked in an oven to evaporate excess alcohol and moisture, causing the anti-fog liquid to solidify on the PP sheet surface, thus achieving the anti-fog effect. However, this invention uses PP as the base layer, which has relatively low mechanical properties. Furthermore, the amphiphilic anti-fog agent in the coating layer of this anti-fog film is carried away by water droplets, leading to a rapid decline in anti-fog performance and a short service life for the anti-fog sheet.

[0006] It is evident that existing methods, such as simply adding anti-fogging agents to a single-layer membrane or coating an anti-fogging liquid onto the outer layer of the membrane, are insufficient to provide long-term, continuous anti-fogging functionality, severely limiting the membrane's lifespan. Furthermore, these methods struggle to balance comprehensive performance characteristics such as light transmittance, anti-fogging properties, and mechanical properties.

[0007] Therefore, how to provide a PET film that has high light transmittance, long-term anti-fog effect, and extended service life while meeting certain mechanical strength requirements has become a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0008] To address the shortcomings of the existing technology, the present invention aims to provide a high-transparency PET film with slow-release and anti-fogging properties and its preparation method. The PET film with high light transmittance, high mechanical properties and anti-fogging slow-release function can be simply manufactured by co-extrusion and biaxial stretching.

[0009] In a first aspect, the present invention provides a slow-release anti-fogging high-transparency PET film, comprising, in sequence:

[0010] 1) PET base film layer;

[0011] 2) First anti-fog layer, the raw materials include: matrix resin A, anti-fog masterbatch A, nucleating agent;

[0012] 3) Slow-release layer, the raw materials of which include: matrix resin B and anti-fogging masterbatch B;

[0013] 4) Second anti-fog layer, the raw materials include: PET resin, anti-fog masterbatch C, nucleating agent;

[0014] Among them, antifog masterbatch A, antifog masterbatch B and antifog masterbatch C are obtained by mixing antifog agent with ternary polyester and granulating.

[0015] The weight of antifog masterbatch A, antifog masterbatch B and antifog masterbatch C accounts for 5-20% of the total weight of their respective layers, and the antifog agent content in the first antifog layer and the antifog agent content in the slow-release layer are both greater than the antifog agent content in the second antifog layer;

[0016] The high-transparency PET film is prepared by four-layer co-extrusion, with a thickness of less than 100 μm, a light transmittance of more than 85%, and a haze of less than 5%.

[0017] This invention uses a PET-based resin matrix to provide sufficient mechanical properties for the film, ensuring its service life. Secondly, by introducing anti-fogging masterbatch into the first, slow-release, and second anti-fogging layers, sufficient anti-fogging function is provided by its anti-fogging agent. Preferably, the anti-fogging agent content decreases sequentially from the first to the slow-release layer, forming an anti-fogging agent precipitation gradient. Furthermore, nucleating agents are used in the first and second anti-fogging layers to regulate the crystallinity and crystal volume of the PET resin, causing the formation of numerous fine spherulites within the PET, thereby increasing the proportion of amorphous material and providing larger channels and space for anti-fogging agent precipitation. A slow-release layer without nucleating agents is inserted between the two anti-fogging layers. The slightly larger PET crystals in the slow-release layer reduce the channels formed by the ternary polyester, prolonging the anti-fogging agent penetration time and achieving controllable layer-by-layer precipitation of the anti-fogging agent.

[0018] This invention constructs a thin film layer structure and composition with slow-release anti-fogging properties, high light transmittance, and good mechanical properties:

[0019] Preferably, the PET base film layer has a thickness of 10-20 μm and contains the following raw material components by weight percentage:

[0020]

[0021] The PET base film layer provides good mechanical support for the film. The antioxidant is one or more of 1098, 1076, 168, and 626 in combination. The lubricating dispersant is one or more of erucamide, EBS, PETS, and calcium stearate in combination. The opening agent is nano-sized BaSO4 or SiO2 used alone or in combination.

[0022] Preferably, the thickness of the first anti-fog layer is 10-20 μm, and it comprises the following raw material components by weight percentage:

[0023]

[0024] The matrix resin A contains more than 90 wt% PET resin, and optionally at least one of LDPE resin, copolymer PP resin, and TPE resin.

[0025] Preferably, the thickness of the sustained-release layer is 5-10 μm, and it comprises the following raw material components by weight percentage:

[0026]

[0027] The matrix resin B contains more than 90 wt% PET resin, and optionally at least one of LDPE resin, copolymer PP resin, and TPE resin.

[0028] Preferably, the thickness of the second anti-fog layer is 30-45 μm, and it comprises the following raw material components by weight percentage:

[0029]

[0030]

[0031] The nucleating agent used in this invention includes TegMeR 809, the antioxidant is selected from at least one of 1098, 1076, 168, and 626, and the lubricating dispersant is at least one of erucamide, EBS, PETS, and calcium stearate.

[0032] Because there is a concentration difference in the anti-fogging masterbatch content between the first and second anti-fogging layers, and a slow-release layer without nucleating agent is inserted in between, the anti-fogging agent in the high-concentration layer takes longer to penetrate to the low-concentration layer, achieving the layer-by-layer precipitation of the anti-fogging agent. When the anti-fogging agent in the second anti-fogging layer is lost, the slow-release layer and the first anti-fogging layer replenish the anti-fogging agent in the second anti-fogging layer through precipitation, achieving the effect of slow release.

[0033] Preferably, antifog masterbatch A, antifog masterbatch B, and antifog masterbatch C are prepared by the following steps:

[0034] (1) A terpolymer polyester was obtained by polymerization of terephthalic acid, ethylene glycol and neopentyl glycol; the neopentyl glycol content accounted for 10-30 mol% of the total glycol content;

[0035] (2) Add the anti-fogging agent to the ternary polyester and extrude and granulate to obtain anti-fogging masterbatch. The content of anti-fogging agent in the anti-fogging masterbatch is 5-25 wt%, more preferably 10-20 wt%.

[0036] Neopentyl glycol (NG) is used for copolymer modification of PET. By adding neopentyl glycol, the melting point and crystallinity of the ternary polyester decrease, while its impact resistance and processability are significantly improved. Furthermore, the anti-fogging agent diffuses well in the ternary polyester and acts as a channel for the anti-fogging agent. The amount of neopentyl glycol used should not be too low, otherwise it will be difficult to reduce crystallinity and disperse the anti-fogging agent; however, excessive amounts may lead to changes in the main properties of PET, reducing interlayer adhesion and the mechanical properties of the finished film.

[0037] The anti-fogging agent used in this invention can be anionic surfactants, nonionic surfactants, cationic surfactants, amphoteric surfactants, etc. Nonionic surfactants are preferred. The anti-fogging agent content in the anti-fogging masterbatch is 5-25 wt%, more preferably 10-20 wt%, thereby adjusting the proportion of the anti-fogging agent in the respective layers. Specifically, based on the decreasing anti-fogging agent content from the first anti-fogging layer to the slow-release layer to the second anti-fogging layer, the proportion of the anti-fogging agent, based on the total mass of each layer, is preferably 0.5 wt% or more, more preferably 1.0 wt% or more. Using an anti-fogging agent within this range provides better anti-fogging performance. Furthermore, the proportion of the anti-fogging agent is preferably 5.0 wt% or less, particularly preferably 4.0 wt% or less. By using an anti-fogging agent within this range, excessive and rapid migration of the anti-fogging agent in each layer can be suppressed, and the reduction in interlayer strength can be prevented.

[0038] Preferably, the PET resin used in the high-transparency PET film comprises virgin PET resin and recycled PET resin in a weight ratio of (50-70):(25-35). The recycled PET resin is the pulverized material after a single extrusion molding process. After sorting, cleaning, and other recycling treatments, it has virtually no impact on product performance and can reduce costs and is more environmentally friendly.

[0039] Preferably, an anti-fog coating layer with a thickness of 5-10 μm is also included on the outside of the second anti-fog layer;

[0040] The anti-fog coating layer comprises, by weight percentage, the following raw material components: 10-18% acrylic grafted modified polyester polyol, 2-4% hexamethylene diisocyanate, 3-5% acetone, 1-4% sodium 3-allyloxy-2-hydroxy-1-propanesulfonate, 2-6% maleic anhydride, 0.3-0.5% defoamer, 1-3% palm wax anti-sticking agent, and 60-70% soft water. The anti-fog coating layer is formed by coating and drying with an anti-fog coating liquid. In addition to the above components, other components may be added to the anti-fog coating liquid as needed, such as UV protectants and antistatic agents.

[0041] Secondly, the present invention provides a method for preparing the aforementioned slow-release anti-fogging high-transparency PET film, comprising the following preparation steps:

[0042] (1) The raw materials of PET base film layer, first anti-fog layer, slow release layer and second anti-fog layer are metered and fed into the corresponding extruders respectively; wherein, the raw materials in each extruder are extruded at a temperature of 200-280℃, pressurized by melt pump, and passed through a filter with a pore size of 10-15 micrometers, and the filter temperature is set in the range of 240-280℃.

[0043] (2) After the raw materials are melted, they enter the four-layer co-extrusion die through the T-shaped frame and extrude four layers of film preform; the die temperature is 200-220℃, and the thickness ratio of each layer in the film is controlled by controlling the melt ratio of the main extrusion and auxiliary extrusion.

[0044] (3) The four-layer film preform is electrostatically adsorbed onto the cold roller to form a cast sheet; the electrostatic voltage is 10±1KV, the thickness of the cast sheet is 450-850μm, the speed of the cold roller is 19-35m / min, and the temperature of the cold roller is 25-32℃.

[0045] (4) The casting is stretched longitudinally with a stretching ratio of 2.6-3.7. Before longitudinal stretching, it is preheated at a temperature of 70-80℃, a cooling temperature of 20-30℃, and a longitudinal stretching and shaping temperature of 30-50℃. Infrared heating is preferred.

[0046] (5) After longitudinal stretching is completed, transverse stretching is performed with a stretching ratio of 3-4 times; preheating is performed before transverse stretching at a preheating temperature of 95-105℃, stretching temperature of 105-115℃, heat setting temperature of 110-120℃, and cooling temperature of 30-60℃ to obtain a film with a thickness of less than 100μm, preferably less than 80μm.

[0047] (6) Single-sided or double-sided corona treatment; optionally, static electricity removal treatment and winding are performed after corona treatment.

[0048] Optionally, prior to step (1), the preparation of an anti-fogging masterbatch is further included, comprising:

[0049] 1) A terpolymer was obtained by polymerization of terephthalic acid, ethylene glycol, and neopentyl glycol; the neopentyl glycol content accounted for 10-30 mol% of the total glycol content; the polymerization reaction was carried out at 175-225℃ using a catalyst with a total monomer content of 0.0005-0.05 wt%; the catalyst was selected from metal catalysts, composite catalysts, etc., for example, antimony, germanium, titanium or combinations thereof could be selected as metal catalysts, and TiO2 / SiO2 could be selected as composite catalysts; the intrinsic viscosity of the obtained terpolymer was 0.65-0.75 dL / g.

[0050] 2) Add the anti-fogging agent to the ternary polyester, and extrude and granulate to obtain anti-fogging masterbatch. The content of anti-fogging agent in the anti-fogging masterbatch is 5-25 wt%, preferably 10-20 wt%.

[0051] Preferably, the raw materials for the PET base film layer, the first anti-fog layer, the slow-release layer, and the second anti-fog layer are respectively put into a high-speed mixing pot for premixing. The high-speed mixing pot rotates at 500-600 r / min for 15-30 min. After being mixed evenly, the mixture is fed into the corresponding extruder by metering.

[0052] Preferably, after step (6), an anti-fog coating liquid is applied to the outer side of the second anti-fog layer, with a unit coating amount of 15-25 g / m². 2 After drying, an anti-fog coating layer is obtained.

[0053] The advantages of this invention are as follows:

[0054] (1) The present invention uses PET as the substrate for the anti-fog layer and the slow-release layer, which has higher overall mechanical strength than the PP resin used in the prior art.

[0055] (2) The present invention uses a nucleating agent to regulate the crystal volume of the PET substrate, so that a large number of small spherulites are formed inside the PET, thereby increasing the proportion of amorphous material. The anti-fogging masterbatch is blended into the substrate, and the ternary polyester introduced into the anti-fogging masterbatch is blended in the PET substrate. The anti-fogging agent is mostly dispersed in the ternary polyester, which is dispersed in the amorphous region, providing a channel for the precipitation of the anti-fogging agent.

[0056] (3) This invention constructs two layers of antifogging agent with different concentrations and inserts a slow-release layer without nucleating agents in between, forming an overall concentration gradient, which is more conducive to the controlled precipitation of the antifogging agent. The slow-release layer does not contain nucleating agents, and the larger PET crystals result in smaller channels formed by the ternary polyester, increasing the time for the antifogging agent from the high-concentration layer to penetrate to the low-concentration layer, achieving layer-by-layer precipitation of the antifogging agent. When the antifogging agent in the low-concentration surface layer is lost, the internal antifogging agent can be replenished. Finally, an antifogging layer is coated on the outermost layer to further enhance the antifogging capability. When the antifogging coating disappears, it consumes the antifogging agent on the PET surface. As the concentration of the surface antifogging agent decreases, the internal antifogging agent gradually precipitates, achieving a slow-release effect and greatly improving the service life of the antifogging film.

[0057] (4) The present invention adopts a multi-layer anti-fog structure based on PET, controls the proportion of anti-fog masterbatch in each layer, and ensures the anti-fog effect. On the basis of this, the crystallinity and grain size of the anti-fog film are reduced by nucleating agent, thereby reducing the overall haze and improving the light transmittance. The light transmittance of the film is above 85%, preferably above 88%, more preferably above 90%, and the haze is below 5%, preferably below 4%. Attached Figure Description

[0058] The above and other objects, features, and advantages of exemplary embodiments of the present disclosure will become readily apparent upon reading the following detailed description with reference to the accompanying drawings. In the drawings, several embodiments of the present disclosure are illustrated by way of example and not limitation, and like or corresponding reference numerals denote like or corresponding parts, wherein:

[0059] Figure 1 This is a schematic diagram of the structure of a slow-release anti-fogging high-transparency PET film according to the present invention;

[0060] Explanation of reference numerals in the attached drawings: 1-PET base film layer, 2-first anti-fog layer, 3-slow-release layer, 4-second anti-fog layer, 5-anti-fog coating layer. Detailed Implementation

[0061] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will now be described in further detail with reference to the accompanying drawings.

[0062] like Figure 1 The slow-release, anti-fogging, high-transparency PET film shown comprises the following layers in sequence:

[0063] 1. PET base film layer 1, with a thickness of 10-20μm, contains the following raw material components by weight percentage: 94-99.6% PET resin, 0.2-2% antioxidant, 0.2-2% lubricant and dispersant, and 0-2% opening agent.

[0064] 2. The first anti-fog layer 2 has a thickness of 10-20 μm and contains the following raw material components by weight percentage: 74-89% matrix resin A, 10-20% anti-fog masterbatch A, 0.6-2% nucleating agent, 0.2-2% antioxidant, and 0.2-2% lubricating dispersant; the matrix resin A contains more than 90 wt% PET resin, and at least one of optional LDPE resin, copolymer PP resin, and TPE resin.

[0065] 3. Slow-release layer 3, the thickness of the slow-release layer is 5-10μm, and by weight percentage, it contains the following raw material components: matrix resin B 76-89.6%, anti-fogging masterbatch B 10-20%, antioxidant 0.2-2%, lubricant and dispersant 0.2-2%; matrix resin B contains more than 90wt% PET resin, and at least one of optional LDPE resin, copolymer PP resin, and TPE resin.

[0066] 4. The second anti-fog layer 4 has a thickness of 30-45μm and contains the following raw material components by weight percentage: 84-91% PET resin, 8-10% anti-fog masterbatch C, 0.6-2% nucleating agent, 0.2-2% antioxidant, and 0.2-2% lubricating dispersant.

[0067] 5. Optional, anti-fog coating layer 5, with a thickness of 5-10 μm; comprising, by weight percentage, the following raw material components: 10-18% acrylic grafted modified polyester polyol, 2-4% hexamethylene diisocyanate, 3-5% acetone, 1-4% sodium 3-allyloxy-2-hydroxy-1-propanesulfonate, 2-6% maleic anhydride, 0.3-0.5% defoamer, 1-3% palm wax anti-sticking agent, and 60-70% soft water.

[0068] The PET resin used in the above film can be entirely made from virgin PET resin. However, considering cost and application, a mixture of virgin and recycled PET resin can also be used, with a weight ratio of (50-70):(25-35).

[0069] Anti-fogging masterbatch A, anti-fogging masterbatch B, and anti-fogging masterbatch C are prepared through the following steps:

[0070] (1) Terephthalic acid, ethylene glycol and neopentyl glycol are polymerized at 175-225℃ to obtain a ternary polyester with an intrinsic viscosity of 0.65-0.75 dL / g; the neopentyl glycol content accounts for 10-30 mol% of the total glycol content.

[0071] (2) Add the anti-fogging agent to the ternary polyester and extrude and granulate to obtain the anti-fogging masterbatch. The content of the anti-fogging agent in the anti-fogging masterbatch is 5-25wt%, more preferably 10-20wt%. Among them, the anti-fogging agent is the relatively environmentally friendly anti-fogging agent N-acylglycine and glyceryl ricinoleate.

[0072] The weight of antifog masterbatch A, antifog masterbatch B, and antifog masterbatch C accounts for 5-20% of the total weight of their respective layers, and the antifog agent content in the first antifog layer and the antifog agent content in the slow-release layer are both greater than the antifog agent content in the second antifog layer; preferably, the antifog agent content in the first antifog layer is greater than the antifog agent content in the slow-release layer, and the antifog agent content in the slow-release layer is greater than the antifog agent content in the second antifog layer.

[0073] The above-mentioned slow-release anti-fogging high-transparency PET film is prepared through the following steps:

[0074] (0) Premixing: The raw materials of PET base film layer, first anti-fog layer, slow release layer and second anti-fog layer are respectively put into a high-speed mixing pot and mixed. The speed of the high-speed mixing pot is 500-600r / min and the time is 15-20min, until the mixture is uniform.

[0075] (1) The raw materials of PET base film layer, first anti-fog layer, slow release layer and second anti-fog layer are metered and fed into the corresponding extruders respectively; wherein, the raw materials in each extruder are extruded at a temperature of 200-280℃, pressurized by melt pump, and passed through a filter with a pore size of 10-15μm, and the filter temperature is set in the range of 240-280℃.

[0076] (2) After passing through the T-shaped frame, the melt enters the four-layer co-extrusion die head. The die head temperature is 200-220℃. The thickness ratio of each layer in the film is controlled by controlling the melt ratio of the main extrusion and auxiliary extrusion.

[0077] (3) After the four-layer film preform is extruded, it is electrostatically adsorbed onto the cold roller to form a cast sheet. The electrostatic wire voltage is 10±1KV, the thickness of the cast sheet is 450-850 micrometers, the cold roller speed is 19-35m / min, and the cold roller temperature is 25-32℃.

[0078] (4) The casting is stretched longitudinally with a stretching ratio of 2.6-3.7; wherein the preheating temperature of the casting is 70-80℃, the cooling temperature is 20-30℃, the longitudinal stretching and shaping temperature is 30-50℃, and the preferred heating method is infrared heating.

[0079] (5) After longitudinal stretching is completed, transverse stretching is carried out with a stretching ratio of 3-4 times; the preheating temperature for transverse stretching is 95-105℃, the stretching temperature is 105-115℃, the heat setting temperature is 110-120℃, and the cooling temperature is 30-60℃.

[0080] (6) Perform static electricity removal treatment on the stretched film and then rewind it.

[0081] (7) Optionally, the wound film is coated with an anti-fogging agent on the coating line. The preheating temperature of the coating line is 35-60℃, the cooling temperature is 20-30℃, and the unit coating amount is 15-30g / m. 2 After drying and setting, static electricity is removed and the film is wound up to obtain a finished PET film with a thickness of less than 100μm.

[0082] Example 1

[0083] The total thickness of the sample in Example 1 is approximately 80 μm, comprising a 15 μm PET base film layer, a 15 μm first anti-fog layer, a 5 μm sustained-release layer, and a 45 μm second anti-fog layer. By weight percentage, each layer comprises the following raw materials:

[0084] 1. PET base film layer, comprising: 99% PET resin (Hengyi Dayou glossy film-grade PET resin); antioxidants are a compound of Rianlong 1076 and 168, with weight ratios of 0.2% and 0.1% respectively; lubricant and dispersant is erucamide, with a weight ratio of 0.3%; opening agent is 632, with a weight ratio of 0.4%.

[0085] 2. The first anti-fog layer comprises: 85% PET (Hengyi Dayou film-grade PET resin); antioxidants are Lianlong 1076 and 168 compounded at a weight ratio of 0.2% and 0.1% respectively; lubricant and dispersant is PETS at a weight ratio of 0.3%; nucleating agent is TegMeR 809 at a weight ratio of 0.6%; and anti-fog masterbatch at a weight ratio of 13.8%.

[0086] 3. Slow-release layer, comprising: 89% PET resin (Hengyi Dayou film grade PET resin); antioxidants are Rianlong 1076 and 168 compounded in weight ratios of 0.2% and 0.1% respectively; lubricant and dispersant is PETS, with a weight ratio of 0.3%; and anti-fogging masterbatch, with a weight ratio of 10.4%.

[0087] 4. The second anti-fog layer comprises: 90% PET resin (Hengyi Dayou film-grade PET resin); antioxidants are Lianlong 1076 and 168 compounded at a weight ratio of 0.2% and 0.1% respectively; lubricant and dispersant is PETS at a weight ratio of 0.3%; nucleating agent is TegMeR 809 at a weight ratio of 0.6%; and anti-fog masterbatch at a weight ratio of 8.8%.

[0088] Anti-fogging masterbatch A, anti-fogging masterbatch B, and anti-fogging masterbatch C have the same composition and are prepared through the following steps:

[0089] (1) A ternary polyester with intrinsic viscosity of 0.70±0.01dL / g was obtained by polymerization of terephthalic acid, ethylene glycol and neopentyl glycol, wherein the neopentyl glycol content accounted for 15 mol% of the total glycol content. The polymerization reaction was carried out under the catalysis of composite catalyst TiO2 / SiO2.

[0090] (2) Add the anti-fogging agent N-acylglycine to the ternary polyester, and extrude and granulate to obtain the anti-fogging masterbatch. The anti-fogging agent content in the anti-fogging masterbatch is 15wt%.

[0091] The film of sample 1 above was prepared by four-layer co-extrusion and biaxial stretching, specifically including the following steps:

[0092] (0) Premixing: The raw materials of PET base film layer, first anti-fog layer, slow release layer and second anti-fog layer are respectively put into a high-speed mixing pot and mixed. The speed of the high-speed mixing pot is 550r / min and the time is 20min. Mix evenly.

[0093] (1) The raw materials of PET base film layer, first anti-fog layer, slow release layer and second anti-fog layer are metered and fed into the corresponding extruders respectively; the above raw materials are extruded in the extruder at a temperature of 200-280℃ (extruder barrel temperature is controlled in sections), pressurized by melt pump, and passed through a filter with a pore size of 15μm, with the filter temperature set in the range of 250±5℃.

[0094] (2) The melt enters the four-layer co-extrusion die after passing through the T-shaped frame. The die temperature is 210±5℃.

[0095] (3) After the four-layer film preform is extruded, it is electrostatically adsorbed onto the cold roller to form a casting. The electrostatic voltage is 10KV, the cold roller speed is 26m / min, and the cold roller temperature is 30℃.

[0096] (4) The casting is stretched longitudinally with a stretching ratio of 3.2. The preheating temperature of the casting is 70℃, 74℃, 76℃, and 77℃, the cooling temperature is 28℃, the longitudinal stretching and shaping temperature is 35℃ and 45℃, the heating method is infrared heating, and the temperature is controlled in multiple stages.

[0097] (5) After longitudinal stretching is completed, transverse stretching is carried out with a stretching ratio of 3.4 times. The transverse stretching preheating temperature is 95℃, 100℃, and 105℃, the stretching temperature is 105℃, 110℃, and 115℃, the heat setting temperature is 110℃, 115℃, and 120℃, and the cooling temperature is 30℃, 45℃, and 60℃. Infrared heating is also used, and multi-stage segmented temperature control is implemented.

[0098] (6) The stretched film is subjected to static electricity removal treatment and wound up to obtain a PET film with a thickness of 80 μm and a four-layer structure.

[0099] Example 2

[0100] The total thickness of the sample in Example 2 is about 80 μm. The difference between Example 2 and Example 1 is that an anti-fog coating layer is provided, and the thickness of some layers is different. The sample in Example 2 includes a 15 μm PET base film layer, a 15 μm first anti-fog layer, a 5 μm slow-release layer, a 40 μm second anti-fog layer, and a 5 μm anti-fog coating layer.

[0101] By weight percentage, each layer comprises the following raw materials:

[0102] 1. PET base film layer, comprising: 99% PET resin (Hengyi Dayou glossy film-grade PET resin); antioxidants are a compound of Rianlong 1076 and 168, with weight ratios of 0.2% and 0.1% respectively; lubricant and dispersant is erucamide, with a weight ratio of 0.3%; opening agent is 632, with a weight ratio of 0.4%.

[0103] 2. The first anti-fog layer comprises: 85% PET (Hengyi Dayou film-grade PET resin); antioxidants are Lianlong 1076 and 168 compounded at a weight ratio of 0.2% and 0.1% respectively; lubricant and dispersant is PETS at a weight ratio of 0.3%; nucleating agent is TegMeR 809 at a weight ratio of 0.6%; and anti-fog masterbatch at a weight ratio of 13.8%.

[0104] 3. Slow-release layer, comprising: 89% PET resin (Hengyi Dayou film grade PET resin); antioxidants are Rianlong 1076 and 168 compounded in weight ratios of 0.2% and 0.1% respectively; lubricant and dispersant is PETS, with a weight ratio of 0.3%; and anti-fogging masterbatch, with a weight ratio of 10.4%.

[0105] 4. The second anti-fog layer comprises: 90% PET resin (Hengyi Dayou film-grade PET resin); antioxidants are Lianlong 1076 and 168 compounded at a weight ratio of 0.2% and 0.1% respectively; lubricant and dispersant is PETS at a weight ratio of 0.3%; nucleating agent is TegMeR 809 at a weight ratio of 0.6%; and anti-fog masterbatch at a weight ratio of 8.8%.

[0106] 5. Coating layer, comprising: 14% acrylic grafted modified polyester polyol, 3% hexamethylene diisocyanate, 4% acetone, 3% sodium 3-allyloxy-2-hydroxy-1-propanesulfonate, 4% maleic anhydride, 0.5% defoamer, 2% palm wax anti-sticking agent, and 69.5% soft water.

[0107] Anti-fogging masterbatch A, anti-fogging masterbatch B, and anti-fogging masterbatch C have the same composition and are prepared through the following steps:

[0108] (1) A ternary polyester with intrinsic viscosity of 0.70±0.01dL / g was obtained by polymerization of terephthalic acid, ethylene glycol and neopentyl glycol, wherein the neopentyl glycol content accounted for 15 mol% of the total glycol content. The polymerization reaction was carried out under the catalysis of composite catalyst TiO2 / SiO2.

[0109] (2) Add the anti-fogging agent N-acylglycine to the ternary polyester, and extrude and granulate to obtain the anti-fogging masterbatch. The anti-fogging agent content in the anti-fogging masterbatch is 15wt%.

[0110] The film of sample 1 above was prepared by four-layer co-extrusion and biaxial stretching, specifically including the following steps:

[0111] (0) Premixing: The raw materials of PET base film layer, first anti-fog layer, slow release layer and second anti-fog layer are respectively put into a high-speed mixing pot and mixed. The speed of the high-speed mixing pot is 550r / min and the time is 20min. Mix evenly.

[0112] (1) The raw materials of PET base film layer, first anti-fog layer, slow release layer and second anti-fog layer are metered and fed into the corresponding extruders respectively; the above raw materials are extruded in the extruder at a temperature of 200-280℃ (extruder barrel temperature is controlled in sections), pressurized by melt pump, and passed through a filter with a pore size of 15μm, with the filter temperature set in the range of 250±5℃.

[0113] (2) The melt enters the four-layer co-extrusion die after passing through the T-shaped frame. The die temperature is 210±5℃.

[0114] (3) After the four-layer film preform is extruded, it is electrostatically adsorbed onto the cold roller to form a casting. The electrostatic voltage is 10KV, the cold roller speed is 26m / min, and the cold roller temperature is 30℃.

[0115] (4) The casting is stretched longitudinally with a stretching ratio of 3.2. The preheating temperature of the casting is 70℃, 74℃, 76℃, and 77℃, the cooling temperature is 28℃, the longitudinal stretching and shaping temperature is 35℃ and 45℃, the heating method is infrared heating, and the temperature is controlled in multiple stages.

[0116] (5) After longitudinal stretching is completed, transverse stretching is carried out with a stretching ratio of 3.4 times. The transverse stretching preheating temperature is 95℃, 100℃, and 105℃, the stretching temperature is 105℃, 110℃, and 115℃, the heat setting temperature is 110℃, 115℃, and 120℃, and the cooling temperature is 30℃, 45℃, and 60℃. Infrared heating is also used, and multi-stage segmented temperature control is implemented.

[0117] (6) The stretched film is subjected to static electricity removal treatment and wound up to obtain a co-extruded biaxially stretched film with a thickness of about 75 μm.

[0118] (7) Apply anti-fogging agent to the wound film on the coating line. The preheating temperature of the coating line is 40℃, 45℃, and 50℃, and the cooling temperature is 25℃. The unit coating amount is 20g / m. 2 After drying and curing, static electricity is removed and the film is wound up to obtain a five-layer PET film with a thickness of approximately 80 μm.

[0119] Example 3

[0120] The total thickness of the sample in Example 3 was approximately 75 μm. The difference between Example 3 and Example 2 was that the thickness of the second anti-fog layer was reduced and the content of anti-fog masterbatch in the first anti-fog layer was different.

[0121] The sample consists of a 15μm PET base film layer, a 15μm first anti-fog layer, a 5μm slow-release layer, a 35μm second anti-fog layer, and a 5μm anti-fog coating layer.

[0122] The first anti-fog layer of the sample in Example 3 comprises: 80% PET (Hengyi Dayou Bright Film Grade PET Resin); antioxidants are Lianlong 1076 and 168 in a compound weight ratio of 0.2% and 0.1% respectively; lubricant and dispersant is PETS in a weight ratio of 0.3%; nucleating agent is TegMeR 809 in a weight ratio of 0.6%; and anti-fog masterbatch in a weight ratio of 18.8%.

[0123] Example 4

[0124] The total thickness of the sample in Example 4 was approximately 70 μm. Compared to Example 3, the difference was that the thickness of the second anti-fog layer was further reduced, and the content of anti-fog masterbatch in the first anti-fog layer was different.

[0125] The sample consists of a 15μm PET base film layer, a 15μm first anti-fog layer, a 5μm slow-release layer, a 30μm second anti-fog layer, and a 5μm anti-fog coating layer.

[0126] The first anti-fog layer of the sample in Example 4 comprises: 80% PET (Hengyi Dayou Bright Film Grade PET Resin); antioxidants are Lianlong 1076 and 168 compounded at a weight ratio of 0.2% and 0.1% respectively; lubricant and dispersant is PETS at a weight ratio of 0.3%; nucleating agent is TegMeR 809 at a weight ratio of 0.6%; and anti-fog masterbatch at a weight ratio of 18.8%.

[0127] Example 5

[0128] The total thickness of the sample in Example 5 is about 75 μm. Compared with Example 4, the difference is that the thickness of the anti-fog coating layer is increased, which includes a 15 μm PET base film layer, a 15 μm first anti-fog layer, a 5 μm slow-release layer, a 30 μm second anti-fog layer, and a 10 μm anti-fog coating layer.

[0129] Example 6

[0130] The total thickness of the sample in Example 6 is about 80 μm. Compared with Example 5, the difference is that the thickness of the sustained-release layer is increased, which includes a 15 μm PET base film layer, a 15 μm first anti-fog layer, a 10 μm sustained-release layer, a 30 μm second anti-fog layer, and a 10 μm anti-fog coating layer.

[0131] Example 7

[0132] The total thickness of the sample in Example 7 is about 75 μm. Compared with Example 4, the difference is that the thickness of the first anti-fog layer is increased, which includes a 15 μm PET base film layer, a 20 μm first anti-fog layer, a 5 μm slow-release layer, a 30 μm second anti-fog layer, and a 5 μm anti-fog coating layer.

[0133] Example 8

[0134] The total thickness of the sample in Example 8 is about 80 μm. Compared with Example 7, the difference is that the thickness of the second anti-fog layer is further increased, which includes a 15 μm PET base film layer, a 20 μm first anti-fog layer, a 5 μm slow-release layer, a 35 μm second anti-fog layer, and a 5 μm anti-fog coating layer.

[0135] Example 9

[0136] The difference between Example 9 and Example 8 is that the PET resin used is a mixture of new and old materials. By weight percentage, each layer specifically comprises the following raw materials:

[0137] 1. PET base film layer, comprising: 69% virgin PET resin (Hengyi Dayou film-grade PET resin), 30% recycled PET resin; antioxidants are a blend of Rianlon 1076 and 168, with weight ratios of 0.2% and 0.1% respectively; lubricant and dispersant is erucamide, with a weight ratio of 0.3%; opening agent is 632, with a weight ratio of 0.4%.

[0138] 2. The first anti-fog layer comprises: 55% virgin PET resin (Hengyi Dayou film-grade PET resin), 30% recycled PET resin; antioxidants are Lianlong 1076 and 168 compounded at a weight ratio of 0.2% and 0.1% respectively; lubricant and dispersant is PETS at a weight ratio of 0.3%; nucleating agent is TegMeR 809 at a weight ratio of 0.6%; and anti-fog masterbatch at a weight ratio of 13.8%.

[0139] 3. Slow-release layer, comprising: 64% virgin PET resin (Hengyi Dayou film grade PET resin), 25% recycled PET resin; antioxidants are Lianlong 1076 and 168 compounded in weight ratios of 0.2% and 0.1% respectively; lubricant and dispersant is PETS, with a weight ratio of 0.3%; and anti-fogging masterbatch, with a weight ratio of 10.4%.

[0140] 4. The second anti-fog layer comprises: 60% virgin PET resin (Hengyi Dayou film-grade PET resin), 30% recycled PET resin; antioxidants are Lianlong 1076 and 168 compounded at a weight ratio of 0.2% and 0.1% respectively; lubricant and dispersant is PETS at a weight ratio of 0.3%; nucleating agent is TegMeR 809 at a weight ratio of 0.6%; and anti-fog masterbatch at a weight ratio of 8.8%.

[0141] 5. Coating layer, comprising: 14% acrylic grafted modified polyester polyol, 3% hexamethylene diisocyanate, 4% acetone, 3% sodium 3-allyloxy-2-hydroxy-1-propanesulfonate, 4% maleic anhydride, 0.5% defoamer, 2% palm wax anti-sticking agent, and 69.5% soft water.

[0142] Example 10

[0143] The total thickness of the sample in Example 10 is about 75 μm. Compared with Example 4, the difference is that the thickness of the PET base film layer is increased, which includes a PET base film layer of 20 μm, a first anti-fog layer of 15 μm, a slow-release layer of 5 μm, a second anti-fog layer of 30 μm, and an anti-fog coating layer of 5 μm.

[0144] The structure and composition of the samples in Examples 1-10 are shown in Table 1.

[0145] Table 1

[0146]

[0147] Tests and Results

[0148] 1. Light transmittance and haze test

[0149] According to GB / T 2410-2008 "Determination of transmittance and haze of transparent plastics", the transmittance and haze of the samples in Examples 1-10 were determined using a WGT-S transmittance / haze meter manufactured by Shanghai Precision Instruments Co., Ltd.

[0150] 2. Slow-release anti-fog effect test

[0151] After immersing the samples in water at room temperature for 0h, 700h, and 1500h, an anti-fog test was conducted according to the national standard GB / T31726-2015.

[0152] 3. Mechanical property testing

[0153] Tensile strength, Young's modulus, elongation at break, and other mechanical properties were tested using an Instron-5565A electronic tensile testing machine, according to GB / T 1040-92 "Test Method for Tensile Properties of Plastics" and GB 13022-91 "Test Method for Tensile Properties of Plastic Films," at a temperature of 253±2℃. The biaxially oriented film sample size was 20mm×150mm, the gauge length was 100mm, and the test rate was 200mm / min. The test results are shown in Table 2.

[0154] Table 2

[0155]

[0156]

[0157] In each embodiment of this invention, five parallel samples were selected for testing, and the average value was taken. Overall, the samples from Examples 1-10 all had light transmittance above 85%, haze below 5%, tensile strength above 160 MPa, and elongation at break above 60%, exhibiting good optical and mechanical properties. Furthermore, the results of the slow-release anti-fogging effect test show that most samples, after being immersed in water for 700 hours, and some even for 1500 hours, still maintained good anti-fogging capabilities. This is related to the multi-layer gradient anti-fogging design of this invention, which provides a high-transmittance PET film with excellent comprehensive performance in slow-release anti-fogging.

[0158] The preferred embodiments of the present invention have been described above, which are intended to make the spirit of the present invention clearer and easier to understand, and are not intended to limit the present invention. All modifications, substitutions and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A slow-release, anti-fogging, high-transparency PET film, characterized in that, In order, they include: 1) PET base film layer; 2) The first anti-fog layer comprises: matrix resin A, anti-fog masterbatch A, and nucleating agent; wherein, matrix resin A contains more than 90 wt% PET resin, and at least one of optional LDPE resin, copolymer PP resin, and TPE resin; 3) The slow-release layer contains the following raw materials: matrix resin B and anti-fogging masterbatch B; wherein the matrix resin B contains more than 90 wt% PET resin, and at least one of LDPE resin, copolymer PP resin, and TPE resin, and the slow-release layer does not contain nucleating agents. 4) Second anti-fog layer, the raw materials of which include: PET resin, anti-fog masterbatch C, and nucleating agent; Among them, antifog masterbatch A, antifog masterbatch B and antifog masterbatch C are obtained by mixing antifog agent with ternary polyester and granulating. The weight of anti-fog masterbatch A, anti-fog masterbatch B and anti-fog masterbatch C accounts for 5-20% of the total weight of their respective layers, and the anti-fog agent content in the first anti-fog layer and the anti-fog agent content in the slow-release layer are both greater than the anti-fog agent content in the second anti-fog layer; The high-transparency PET film is prepared by four-layer co-extrusion, with a thickness of less than 100 μm, a light transmittance of more than 85%, and a haze of less than 5%.

2. The high-transparency PET film as described in claim 1, characterized in that, The PET base film layer has a thickness of 10-20 μm and contains the following raw material components by weight percentage: PET resin 94-99.6%; Antioxidant 0.2-2%; Lubricating dispersant 0.2-2%; Opening agent 0-2%.

3. The high-transparency PET film as described in claim 1, characterized in that, The first anti-fog layer has a thickness of 10-20 μm and contains the following raw material components by weight percentage: Matrix resin A 74-89%; Antifog masterbatch A 10-20%; Nucleating agent 0.6-2%; Antioxidant 0.2-2%; Lubricating dispersant 0.2-2%.

4. The high-transparency PET film as described in claim 1, characterized in that, The sustained-release layer has a thickness of 5-10 μm and contains the following raw material components by weight percentage: Matrix resin B 76-89.6%; Antifog masterbatch B 10-20%; Antioxidant 0.2-2%; Lubricating dispersant 0.2-2%.

5. The high-transparency PET film according to any one of claims 1-4, characterized in that, The second anti-fog layer has a thickness of 30-45 μm and contains the following raw material components by weight percentage: PET resin 84-91%; Antifog masterbatch C 8-10%; Nucleating agent 0.6-2%; Antioxidant 0.2-2%; Lubricating dispersant 0.2-2%.

6. The high-transparency PET film as described in claim 5, characterized in that, Antifog masterbatch A, antifog masterbatch B, and antifog masterbatch C are prepared respectively through the following steps: (1) A terpolymer polyester was obtained by polymerization of terephthalic acid, ethylene glycol and neopentyl glycol; the neopentyl glycol content accounted for 10-30 mol% of the total glycol content; (2) Add the anti-fogging agent to the ternary polyester, and extrude and granulate to obtain anti-fogging masterbatch. The content of anti-fogging agent in the anti-fogging masterbatch is 5-25wt%.

7. The high-transparency PET film as described in claim 5, characterized in that, The PET resin used in the high-transparency PET film comprises virgin PET resin and recycled PET resin in a weight ratio of (50-70):(25-35).

8. The high-transparency PET film as described in claim 5, characterized in that, An anti-fog coating layer with a thickness of 5-10 μm is also included on the outside of the second anti-fog layer; By weight percentage, the antifog coating layer comprises the following raw material components: 10-18% acrylic grafted modified polyester polyol, 2-4% hexamethylene diisocyanate, 3-5% acetone, 1-4% sodium 3-allyloxy-2-hydroxy-1-propanesulfonate, 2-6% maleic anhydride, 0.3-0.5% defoamer, 1-3% palm wax anti-sticking agent, and 60-70% soft water.

9. A method for preparing a high-transparency PET film with slow-release anti-fogging as described in any one of claims 1-8, characterized in that, The preparation steps include the following: (1) The raw materials for the PET base film layer, the first anti-fog layer, the slow-release layer and the second anti-fog layer are metered and fed into the corresponding extruders respectively; (2) After the raw materials are melted, they enter the four-layer co-extrusion die through the T-shaped frame and extrude the four-layer film preform; (3) The four-layer film preform is electrostatically adsorbed onto the cold roller to form a cast sheet; (4) The casting is stretched longitudinally with a stretching ratio of 2.6-3.7; (5) After longitudinal stretching is completed, transverse stretching is performed with a stretching ratio of 3-4 times; (6) Single-sided or double-sided corona treatment; optionally, static electricity removal treatment and winding are performed after corona treatment.

10. The preparation method according to claim 9, characterized in that, After step (6), an anti-fog coating liquid is applied to the outside of the second anti-fog layer, with a unit coating amount of 15-25 g / m². 2 After drying, an anti-fog coating layer is obtained.

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