Washable coating polyester shrink film and preparation system thereof

Abstract

The utility model provides a washable coating polyester shrink film. The washable coating polyester shrink film consists of a PETG (polyethylene terephthalate glycol) base film and a washable coating positioned on at least one side surface of the PETG base film, the thickness of the PETG base film is 20 to 50 [mu] m; and the thickness of the washable coating is 5-10 [mu] m. The utility model also provides a preparation system for the washable coating polyester shrink film, which comprises a first receiving roller for providing a PETG base film, and a coating mechanism for forming the washable coating on at least one side surface of the PETG base film is arranged at the downstream of the first receiving roller. A drying device for drying the washable coating is arranged at the downstream of the coating mechanism, and a second receiving roller is arranged at the downstream of the drying device; the preparation system further comprises a washable coating preparation device for providing washable coating for the coating mechanism. The polyester shrink film with the washable coating has excellent washability, the coating is firm, and the polyester shrink film has better durability.

Description

Technical Field

[0001] The present application relates to a washable coated polyester shrink film and a preparation system thereof. Background Art

[0002] As an outer packaging material for products, in addition to being able to form a tight fit with the packaged items during shrinkage, shrink films usually also need to be able to protect the products to be more durable during transportation and storage and not be easily affected by moisture and abrasion. Therefore, sometimes shrink films need to have certain water resistance. Especially in food packaging, shrink films need to withstand various conditions, including contact with moisture, and providing water resistance can ensure the following advantages:

[0003] 1. Protect the quality and safety of the packaged items: The packaging of food and other items usually needs to come into contact with moisture during transportation and storage. If the shrink film is not water-resistant, moisture may penetrate into the interior of the packaged items, causing food spoilage or damage to other items, thereby affecting the quality and safety of the products.

[0004] 2. Prevent packaging failure: If the shrink film is not water-resistant, it may become loose or lose its original shrinkage performance after coming into contact with moisture, resulting in packaging failure and being unable to effectively protect the internal items. This is especially important because one of the basic functions of packaging is to maintain the freshness and integrity of the product.

[0005] 3. Meet industry standards and regulatory requirements: Many countries and regions have strict requirements for food packaging materials, including water resistance. As a commonly used packaging material, shrink films need to comply with these standards and regulations to ensure the safety and compliance of the products.

[0006] Therefore, in order to ensure that the shrink film can effectively protect the packaged items, prevent moisture intrusion and maintain its original function, it needs to have good water resistance characteristics.

[0007] Although the commonly used existing PETG shrink films perform well in general humid environments (such as high humidity, short-term contact with moisture), under the conditions of water flow flushing or washing, the PETG molecules may soften or dissolve when impacted by water flow or washed with water, which may cause it to rupture and lose its protective function. Therefore, for specific product packaging requirements, in addition to being water-resistant, the shrink film also needs to have additional washability.

[0008] In addition, there is almost no preparatory system for washable shrink films available for reference in the prior art. Summary of the Invention

[0009] The technical problem to be solved by the present application is to provide a washable coated polyester shrink film and a preparation system thereof to reduce or avoid the problems mentioned above.

[0010] To solve the above technical problems, the present application proposes a washable coated polyester shrink film, which is composed of a PETG base film and a washable coating located on at least one surface of the PETG base film; the thickness of the PETG base film is 20 - 50 μm; the thickness of the washable coating is 5 - 10 μm.

[0011] The present utility model also proposes a preparation system for the above washable coated polyester shrink film, including a first winding roller for providing the PETG base film, a coating mechanism for forming a washable coating on at least one surface of the PETG base film is arranged downstream of the first winding roller, a drying device for drying the washable coating is arranged downstream of the coating mechanism, and a second winding roller is arranged downstream of the drying device; the preparation system further includes a washable coating preparation device for providing the washable coating to the coating mechanism.

[0012] Preferably, the washable coating preparation device includes a first mixing tank for mixing sodium dodecylbenzenesulfonate, 2 - hydroxy - 4 - (3 - triethoxysilylpropoxy) benzophenone, and ethanol, the outlet of the first mixing tank is connected to a second mixing tank added with polyurethane emulsion, polypropylene emulsion, and epoxy resin, and the outlet of the second mixing tank is connected to the coating mechanism.

[0013] Preferably, the preparation system further includes a functional masterbatch preparation device for preparing the functional masterbatch of the PETG shrink film; the outlet of the functional masterbatch preparation device is connected to the inlet of a twin - screw extruder, the outlet of the twin - screw extruder is connected to the inlet of a casting unit, the outlet of the casting unit is connected to the inlet of a stretching mechanism, the outlet of the stretching mechanism is connected to the inlet of a cooling mechanism, and the outlet of the cooling mechanism is connected to the first winding roller.

[0014] Preferably, the functional masterbatch preparation device includes at least one esterification tank and a polycondensation tank. The esterification tank has a first inlet for terephthalic acid, a second inlet for ethylene glycol, and a third inlet for connecting the outlet of an esterification auxiliary material tank; the polycondensation tank has a fourth inlet for connecting the outlet of the esterification tank, a fifth inlet for connecting the outlet of a polycondensation auxiliary material tank, and a sixth inlet for potassium tripolyphosphate; the outlet of the polycondensation tank is connected to at least one extruder, the outlet of the extruder is connected to a pelletizer, the outlet of the pelletizer is connected to a dryer, and the outlet of the dryer is connected to the inlet of the twin - screw extruder.

[0015] The washable coated polyester shrink film of the present application has excellent washability, the coating is firm, and has better durability. In addition, the present application proposes a preparation system for the washable coated polyester shrink film, which has a simple and practical structure and fills the gap in the prior art of lacking an available preparation system. Description of the Drawings

[0016] The following drawings are only intended to illustrate and explain the present application schematically and do not limit the scope of the present application.

[0017] Figure 1 It shows a schematic cross-sectional structure diagram of a washable coated polyester shrink film according to the present application.

[0018] Figure 2 It shows a schematic cross-sectional structure diagram of another washable coated polyester shrink film according to the present application.

[0019] Figure 3 It shows a schematic structure diagram of a preparation system of a washable coated polyester shrink film according to a specific embodiment of the present application.

[0020] Figure 4 It shows a schematic structure diagram of a preparation device for a washable coating according to a specific embodiment of the present application.

[0021] Figure 5 It shows a schematic structure diagram of a preparation system of a washable coated polyester shrink film according to another specific embodiment of the present application.

[0022] Figure 6 It shows a schematic structure diagram of a preparation device for a functional masterbatch according to a specific embodiment of the present application. Detailed Embodiments

[0023] For a clearer understanding of the technical features, objectives, and effects of the present application, the specific embodiments of the present application are now described with reference to the accompanying drawings. Among them, the same components are denoted by the same reference numerals.

[0024] As Figure 1-2 shown, the present utility model provides a washable coated polyester shrink film, which is composed of a PETG base film 1 and a washable coating 2 located on at least one surface of the PETG base film 1. Generally speaking, the washable coating 2 can be coated on one surface of the PETG base film 1 facing the outside of the package. In special application environments, such as when packaging frozen water-containing products, the effect will be better. For example, Figure 2 shown, in a specific embodiment of the washable coated polyester shrink film shown, washable coatings 2 are provided on both sides of the PETG base film 1.

[0025] Among them, the washable coating is formed by coating a washable coating on the outside of the substrate and drying it at a low temperature.

[0026] The washable coating is prepared from the following raw materials in parts by weight: 20-25 parts by weight of polyurethane emulsion, 15-20 parts by weight of polypropylene emulsion, 4-8 parts by weight of epoxy resin, 1-3 parts by weight of sodium dodecylbenzenesulfonate, 5-10 parts by weight of 2-hydroxy-4-(3-triethoxysilylpropoxy) benzophenone, and 10-15 parts by weight of ethanol.

[0027] Among them, the polyurethane emulsion can be selected from BASF Luhydran 938ap or BASF JONCRYL FLX series polyurethane emulsions; the polypropylene emulsion can be selected from BASF Acronal series acrylic emulsions, such as BASF Acronal2640, etc.

[0028] The washable coating of the present application can be prepared through the following steps: uniformly mixing 1-3 parts by weight of sodium dodecylbenzenesulfonate, 5-10 parts by weight of 2-hydroxy-4-(3-triethoxysilylpropoxy) benzophenone, and 10-15 parts by weight of ethanol, heating to 50 °C, and standing for hydrolysis for 1-2 hours; uniformly mixing the hydrolyzed product with 20-25 parts by weight of polyurethane emulsion, 15-20 parts by weight of polypropylene emulsion, and 4-8 parts by weight of epoxy resin to obtain the washable coating of the present application.

[0029] Among them, the PETG base film can be made of an existing PETG shrink film and can be obtained by purchasing in the market. Or, it can also be prepared from the PETG shrink film functional masterbatch prepared by the present application, which will be described in detail later.

[0030] The washable coated polyester shrink film of the present application can be prepared by the following method: for example, coating the prepared washable coating on at least one side surface of the PETG base film and drying for 5-10 minutes under the condition of a temperature of 40-50 °C to obtain the washable coating. Preferably, the thickness of the prepared washable coating is 5-10 μm.

[0031] Corresponding to the above preparation method, as Figure 3 shown, the present application also provides a preparation system for the washable coated polyester shrink film. The preparation system includes a first winding roller 560 for providing the PETG base film 1. A coating mechanism 401 for forming a washable coating 2 on at least one side surface of the PETG base film 1 is arranged downstream of the first winding roller 560. A drying device 402 for drying the washable coating is arranged downstream of the coating mechanism 401. A second winding roller 403 is arranged downstream of the drying device 402.

[0032] Furthermore, corresponding to the preparation of the aforementioned washable coating, the preparation system of the present application can also include a washable coating preparation device 400 for providing the washable coating to the coating mechanism 401.

[0033] Among them, Figure 4 Figure 1 shows a schematic structural diagram of a washable coating preparation device according to a specific embodiment of the present application. As shown in the figure, the washable coating preparation device 400 may include a first mixing tank 410 for mixing sodium dodecylbenzenesulfonate, 2-hydroxy-4-(3-triethoxysilylpropoxy) benzophenone, and ethanol. The outlet of the first mixing tank 410 is connected to a second mixing tank 420 added with polyurethane emulsion, polypropylene emulsion, and epoxy resin. The outlet of the second mixing tank 420 is connected to the coating mechanism 401.

[0034] In the washable coating of the present application, silanol is obtained by hydrolyzing 2-hydroxy-4-(3-triethoxysilylpropoxy) benzophenone in an alkaline environment composed of sodium dodecylbenzenesulfonate and ethanol, and then polymerized into a polysiloxane chain, and then dispersed into a polymer film-forming emulsion. The hydrolysis equation is:

[0035] Si(OC 2 H 5 ) 3 -CH 2 -CH 2 -CH 2 -O-C 6 H 5 +3H 2 O→Si(OH) 3 -CH 2 -CH 2 -CH 2 -O-C 6 H 5 +3C 2 H 5 OH

[0036] The dispersed polysiloxane chains are firmly combined with the PETG base film and the polymer film-forming components, which can prevent the washable coating on the surface from cracking or falling off when the shrink film shrinks. In addition, a small amount of unhydrolyzed 2-hydroxy-4-(3-triethoxysilylpropoxy) benzophenone can still play the function of preventing ultraviolet rays, and can also prevent shrinkage and migration to the surface of the film during washing due to the combination with the hydrolyzed components, which can improve the durability of the shrink film.

[0037] Further, as described above, the present application may also be self-provided with a PETG base film prepared from a PETG shrink film functional masterbatch. Among them, the PETG shrink film functional masterbatch is prepared from the following raw materials in parts by weight: 100-120 parts by weight of terephthalic acid, 30-50 parts by weight of 1,4-cyclohexanedimethanol, 80-100 parts by weight of ethylene glycol, 0.1-0.2 parts by weight of triaryl phosphate, 0.01-0.03 parts by weight of isocyanate, 0.01-0.02 parts by weight of tripotassium phosphate, 0.1-0.2 parts by weight of magnesium aluminum silicate, 0.2-0.4 parts by weight of disodium ethylenediaminetetraacetate, and 0.3-0.5 parts by weight of other additives.

[0038] Among them, other additives include but are not limited to one or a combination of anti-blocking agents, antioxidants, stabilizers, leveling agents, flame retardants, etc.

[0039] Further, the PETG shrink film functional masterbatch of the present application can be prepared by the following steps.

[0040] For example, 100-120 parts by weight of terephthalic acid and 80-100 parts by weight of ethylene glycol can be added to an esterification tank respectively, and uniformly mixed at room temperature for a pre-reaction of 30-60 minutes. Then, 30-50 parts by weight of 1,4-cyclohexanedimethanol, 0.1-0.2 parts by weight of triaryl phosphate, and 0.01-0.03 parts by weight of isocyanate, which are uniformly mixed, are added to the esterification tank. The reaction conditions of the esterification tank are set to 230-250°C and 0.2-0.3 Mpa for an esterification reaction. After the water output reaches the theoretical value, the system pressure is released to atmospheric pressure.

[0041] Then, the esterification product is filtered and transferred from the outlet of the esterification tank to a polycondensation tank. At the same time, 0.01-0.02 parts by weight of tripotassium phosphate are added to the polycondensation tank, and the temperature is maintained at 230-250°C and stirred at atmospheric pressure for 10 minutes. Then, vacuum is pumped, the temperature in the polycondensation tank is raised to 285°C, the pressure is reduced to below 100 Pa, and the reaction is carried out for more than 3 hours until the intrinsic viscosity reaches 0.80 dl / g or more. The temperature is then lowered to 230°C and the pressure is restored to atmospheric pressure.

[0042] 0.1-0.2 parts by weight of magnesium aluminum silicate, 0.2-0.4 parts by weight of disodium ethylenediaminetetraacetate, and 0.3-0.5 parts by weight of other additives, which are uniformly mixed, are added to the polycondensation tank.

[0043] The temperature in the polycondensation tank is maintained at 230°C and stirred for 30 minutes. Finally, the polymer melt is filtered, extruded, pelletized, and dried from the outlet of the polycondensation tank to obtain the PETG shrink film functional masterbatch.

[0044] Further, the washable coated polyester shrink film of the present application can also be prepared by the following steps.

[0045] For example, the prepared PETG shrink film functional masterbatch is melt-extruded through an extruder, cast into a sheet by a die head, transversely stretched by far-infrared rays, cooled and shaped, wound up, and slit to produce a PETG base film. The thickness of the PETG base film is 20-50 μm. Then, the prepared washable coating is applied to one surface of the substrate and dried at a temperature of 40-50 °C for 5-10 minutes to obtain a washable coating. Preferably, the thickness of the prepared washable coating is 5-10 μm.

[0046] Corresponding to the above preparation method, the present application proposes a preparation system for a washable coating polyester shrink film of another specific embodiment, as Figure 5 shown. Similar to the Figure 3 specific embodiment shown, the preparation system of this embodiment further includes a functional masterbatch preparation device 1000 for preparing a PETG shrink film functional masterbatch on the basis of the embodiment shown in Figure 3 ; the outlet of the functional masterbatch preparation device 1000 is connected to the inlet of a twin-screw extruder 510, the outlet of the twin-screw extruder 510 is connected to the inlet of a sheet casting unit 520, the outlet of the sheet casting unit 520 is connected to the inlet of a stretching mechanism 540, the outlet of the stretching mechanism 540 is connected to the inlet of a cooling mechanism 550, and the outlet of the cooling mechanism 550 is connected to the first winding roller 560.

[0047] Among them, Figure 6 shows a schematic structural diagram of a functional masterbatch preparation device of a specific embodiment of the present application. As shown in the figure, the functional masterbatch preparation device 1000 of the present application may include at least one esterification tank 100 and one polycondensation tank 200. Those skilled in the art should understand that the functional masterbatch preparation device 1000 of the present application is not limited to only one esterification tank and one polycondensation tank. For example, for different production scales, two or more esterification tanks 100 and two or more polycondensation tanks 200 can be connected in series in sequence, where the previous esterification tank 100 and polycondensation tank 200 are used for pre-reaction, and the last esterification tank 100 and polycondensation tank 200 are used for final reaction.

[0048] Among them, the esterification tank 100 has a first inlet 101 for terephthalic acid, a second inlet 102 for ethylene glycol, and a third inlet 103 for connecting the outlet of an esterification auxiliary material tank 300.

[0049] Among them, the esterification auxiliary material tank 300 is provided with three inlets corresponding to the input of 1,4-cyclohexanedimethanol, triaryl phosphate, and isocyanate respectively. Initially, terephthalic acid and ethylene glycol can be added first for pre-reaction, and then the three auxiliary materials mixed in the esterification auxiliary material tank 300 are added to the esterification tank 100.

[0050] The polycondensation tank 200 has a fourth inlet 204 for connecting to the outlet of the esterification tank 100, a fifth inlet 205 for connecting to the outlet of the polycondensation auxiliary material tank 301, and a sixth inlet 206 for potassium tripolyphosphate.

[0051] Among them, the polycondensation auxiliary material tank 301 is provided with three inlets corresponding to the input of magnesium aluminum silicate, disodium ethylenediaminetetraacetate, and other auxiliaries respectively. Initially, potassium tripolyphosphate can be added first for pre-reaction, and then the three mixed auxiliaries in the polycondensation auxiliary material tank 301 are added to the polycondensation tank 200.

[0052] Furthermore, the outlet of the polycondensation tank 200 is connected to at least one extruder 600, the outlet of the extruder 600 is connected to a pelletizer 700, and the outlet of the pelletizer 800 is connected to a dryer 800. The outlet of the dryer 800 is connected to the inlet of the twin-screw extruder 510.

[0053] Example 1

[0054] 1 part by weight of sodium dodecylbenzenesulfonate, 5 parts by weight of 2-hydroxy-4-(3-triethoxysilylpropoxy)benzophenone, and 10 parts by weight of ethanol are uniformly mixed, heated to 50 °C, and left to hydrolyze for 1 hour; the hydrolyzed product is uniformly mixed with 20 parts by weight of polyurethane emulsion (BASF Luhydran 938ap), 15 parts by weight of polypropylene emulsion (BASF Acronal2640), and 4 parts by weight of epoxy resin to prepare the washable coating of this example.

[0055] The prepared washable coating is applied to one side surface of a 20-μm PETG base film and dried at a temperature of 40 °C for 5 minutes to prepare a polyester shrink film with a 5-μm-thick washable coating.

[0056] The polyester shrink film is heated and shrunk at 120 °C and left outdoors naturally for 30 days, and rinsed for 30 minutes every day. The polyester shrink film has no coating peeling off, and the shrink film is intact as a whole without damage.

[0057] Example 2

[0058] 2 parts by weight of sodium dodecylbenzenesulfonate, 8 parts by weight of 2-hydroxy-4-(3-triethoxysilylpropoxy)benzophenone, and 12 parts by weight of ethanol are uniformly mixed, heated to 50 °C, and left to hydrolyze for 1.5 hours; the hydrolyzed product is uniformly mixed with 23 parts by weight of polyurethane emulsion (BASF Luhydran 938ap), 18 parts by weight of polypropylene emulsion (BASF Acronal2640), and 6 parts by weight of epoxy resin to prepare the washable coating of this example.

[0059] The prepared washable coating was applied to one side surface of a 30-μm PETG base film and dried at a temperature of 45 °C for 8 minutes to obtain a polyester shrink film with a washable coating having a thickness of 8 μm.

[0060] The polyester shrink film was heat-shrunk at 120 °C, placed outdoors naturally for 30 days, and rinsed for 30 minutes every day. There was no coating peeling off, and the shrink film was intact as a whole without damage.

[0061] Example 3

[0062] 3 parts by weight of sodium dodecylbenzenesulfonate, 10 parts by weight of 2-hydroxy-4-(3-triethoxysilylpropoxy) benzophenone, and 15 parts by weight of ethanol were uniformly mixed and heated to 50 °C, then left standing for hydrolysis for 2 hours; the hydrolyzed product was uniformly mixed with 25 parts by weight of polyurethane emulsion (BASF Luhydran 938ap), 20 parts by weight of polypropylene emulsion (BASF Acronal 2640), and 8 parts by weight of epoxy resin to obtain the washable coating of this example.

[0063] The prepared washable coating was applied to one side surface of a 50-μm PETG base film and dried at a temperature of 50 °C for 10 minutes to obtain a polyester shrink film with a washable coating having a thickness of 10 μm.

[0064] The polyester shrink film was heat-shrunk at 120 °C, placed outdoors naturally for 30 days, and rinsed for 30 minutes every day. There was no coating peeling off, and the shrink film was intact as a whole without damage.

[0065] Comparative Examples 4 - 6

[0066] Referring to the same processes of Examples 1 - 3 respectively, washable coatings were formulated with the raw material parts by weight in the following list, and polyester shrink films with washable coatings were obtained. Whether the wash coatings peeled off or the shrink films cracked was tested under the same conditions.

[0067] In the table, each letter component represents:

[0068] A: Sodium dodecylbenzenesulfonate; B: 2-hydroxy-4-(3-triethoxysilylpropoxy) benzophenone; C: Ethanol; D: Polyurethane emulsion; E: Polypropylene emulsion; F: Epoxy resin

[0069] Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 Comparative Example 6 A 0 2 3 1 2 3 B 5 0 10 5 8 10 C 10 12 0 10 12 15 D 20 23 25 0 23 25 E 15 18 20 15 0 20 F 4 6 8 4 6 0 Base film thickness 20μm 30μm 50μm 20μm 30μm 50μm Coating thickness 5μm 8μm 10μm 5μm 8μm 10μm Water washing effect Detachment Detachment Detachment Fracture Fracture Fracture

[0070] The performance of the washable coating polyester shrink film prepared from the PETG shrink film functional masterbatch prepared by this application is as follows.

[0071] Example 4

[0072] Add 100 parts by weight of terephthalic acid, 80 parts by weight of ethylene glycol, 30 parts by weight of 1,4-cyclohexanedimethanol, 0.1 part by weight of triaryl phosphate, and 0.01 part by weight of isocyanate into an esterification tank, and carry out an esterification reaction.

[0073] Transfer the esterification product to a polycondensation tank, and add 0.01 part by weight of potassium tripolyphosphate, 0.1 part by weight of magnesium aluminum silicate, 0.2 part by weight of disodium ethylenediaminetetraacetate, and 0.3 part by weight of nano-calcium carbonate anti-blocking agent into the polycondensation tank, and carry out a polycondensation reaction.

[0074] In this example, the intrinsic viscosity of the polycondensation reaction product can reach a maximum of 0.80 dl / g.

[0075] Finally, extrude, pelletize, and dry the polymer melt to obtain a PETG shrink film functional masterbatch.

[0076] Melt-extrude the prepared PETG shrink film functional masterbatch, cast film with a die head, stretch transversely by far-infrared, cool and shape, wind up, and slit to make a PETG base film.

[0077] The maximum shrinkage temperature of the prepared PETG base film is 81 °C, the transverse thermal shrinkage rate in 2 - 3 seconds is 71%, the light transmittance is 95%, and the shrinkage force is 6.1 N / m 2 , and the thickness is 50 μm.

[0078] Coat the one-side surface of the prepared PETG base film with the washable coating of Example 1, and dry at 40 °C for 5 minutes to prepare a polyester shrink film with a washable coating having a thickness of 5 μm.

[0079] Heat-shrink the polyester shrink film at 80 °C, place it outdoors naturally for 30 days, and rinse it for 30 minutes every day. The polyester shrink film has no coating peeling off, and the shrink film is integral and intact without damage.

[0080] Example 5

[0081] Add 110 parts by weight of terephthalic acid, 90 parts by weight of ethylene glycol, 40 parts by weight of 1,4-cyclohexanedimethanol, 0.15 part by weight of triaryl phosphate, and 0.02 part by weight of isocyanate into an esterification tank, and carry out an esterification reaction.

[0082] Transfer the esterification product to a polycondensation tank, and add 0.015 part by weight of potassium tripolyphosphate, 0.15 part by weight of magnesium aluminum silicate, 0.3 part by weight of disodium ethylenediaminetetraacetate, and 0.4 part by weight of polytetrahydrofuran leveling agent into the polycondensation tank, and carry out a polycondensation reaction.

[0083] In this example, the intrinsic viscosity of the polycondensation reaction product can reach a maximum of 0.81 dl / g.

[0084] Finally, the aggregated melt is extruded, pelletized, and dried to obtain the PETG shrink film functional masterbatch.

[0085] The prepared PETG shrink film functional masterbatch is melt-extruded, die-cast into sheets, transversely far-infrared stretched, cooled and shaped, wound, and slit to produce a PETG base film.

[0086] The produced PETG base film has a maximum shrinkage temperature of 80 °C, a transverse thermal shrinkage rate of 73% in 2 - 3 seconds, a light transmittance of 94%, and a shrinkage force of 5.8 N / m 2 , and a thickness of 50 μm.

[0087] The washable coating of Example 2 is coated on one side surface of the prepared PETG base film and dried at 45 °C for 8 minutes to obtain a polyester shrink film with a washable coating having a thickness of 8 μm.

[0088] The polyester shrink film is heat-shrunk at 80 °C and naturally placed outdoors for 30 days, and rinsed for 30 minutes every day. The coating of the polyester shrink film does not peel off, and the whole shrink film remains intact without damage.

[0089] Example 6

[0090] 120 parts by weight of terephthalic acid, 100 parts by weight of ethylene glycol, 50 parts by weight of 1,4-cyclohexanedimethanol, 0.2 parts by weight of triaryl phosphate, and 0.03 parts by weight of isocyanate are added to an esterification tank for esterification reaction.

[0091] The esterification product is transferred to a polycondensation tank, and 0.02 parts by weight of potassium tripolyphosphate, 0.2 parts by weight of magnesium aluminum silicate, 0.4 parts by weight of disodium ethylenediaminetetraacetate, 0.3 parts by weight of nano-titanium dioxide stabilizer, and 0.2 parts by weight of decabromodiphenyl ether flame retardant are added to the polycondensation tank for polycondensation reaction.

[0092] In this example, the intrinsic viscosity of the polycondensation reaction product can reach a maximum of 0.82 dl / g.

[0093] Finally, the aggregated melt is extruded, pelletized, and dried to obtain the PETG shrink film functional masterbatch.

[0094] The prepared PETG shrink film functional masterbatch is melt-extruded, die-cast into sheets, transversely far-infrared stretched, cooled and shaped, wound, and slit to produce a PETG base film.

[0095] The produced PETG base film has a maximum shrinkage temperature of 80 °C, a transverse thermal shrinkage rate of 72% in 2 - 3 seconds, a light transmittance of 93%, and a shrinkage force of 6.2 N / m 2 , and a thickness of 50 μm.

[0096] Coat the one-side surface of the prepared PETG base film with the washable coating of Example 3, and dry it for 10 minutes under the condition of a temperature of 50°C to obtain a polyester shrink film with a washable coating having a thickness of 10 μm.

[0097] Heat-shrink the polyester shrink film at 80°C, place it outdoors naturally for 30 days, and rinse it for 30 minutes every day. There is no coating peeling off the polyester shrink film, and the whole shrink film is intact without damage.

[0098] Comparative Example 7

[0099] Add 100 parts by weight of terephthalic acid, 80 parts by weight of ethylene glycol, and 30 parts by weight of 1,4-cyclohexanedimethanol to the esterification tank for esterification reaction.

[0100] Transfer the esterification product to the polycondensation tank, add 0.3 parts by weight of nano calcium carbonate anti-blocking agent to the polycondensation tank, carry out polycondensation reaction, and finally extrude, pelletize, and dry the polymerization melt to obtain the PETG shrink film functional masterbatch.

[0101] In this comparative example, the intrinsic viscosity of the polycondensation reaction product can reach a maximum of 0.69 dl / g.

[0102] Melt-extrude, die-cast sheet, transversely far-infrared stretch, cool and shape, wind up, and slit the prepared PETG shrink film functional masterbatch to make a shrink film.

[0103] The maximum shrinkage temperature of the prepared film is 120°C, the transverse thermal shrinkage rate in 2 - 3 seconds is 67%, the light transmittance is 85%, and the shrinkage force is 6.9 N / m 2 , and the thickness is 50 μm.

[0104] Comparative Example 8

[0105] Add 110 parts by weight of terephthalic acid, 90 parts by weight of ethylene glycol, 40 parts by weight of 1,4-cyclohexanedimethanol, 0.15 parts by weight of triaryl phosphate, and 0.02 parts by weight of isocyanate to the esterification tank for esterification reaction.

[0106] Transfer the esterification product to the polycondensation tank, add 0.4 parts by weight of polytetrahydrofuran leveling agent to the polycondensation tank, carry out polycondensation reaction, and finally extrude, pelletize, and dry the polymerization melt to obtain the PETG shrink film functional masterbatch.

[0107] In this comparative example, the intrinsic viscosity of the polycondensation reaction product can reach a maximum of 0.71 dl / g.

[0108] Melt-extrude, die-cast sheet, transversely far-infrared stretch, cool and shape, wind up, and slit the prepared PETG shrink film functional masterbatch to make a shrink film.

[0109] The maximum shrinkage temperature of the prepared film is 115°C, the transverse thermal shrinkage rate in 2 - 3 seconds is 73%, the light transmittance is 88%, and the shrinkage force is 6.7 N / m 2 , and the thickness is 50 μm.

[0110] Comparative Example 9

[0111] Add 120 parts by weight of terephthalic acid, 100 parts by weight of ethylene glycol, 50 parts by weight of 1,4 - cyclohexanedimethanol, 0.2 parts by weight of triaryl phosphate, and 0.03 parts by weight of isocyanate into the esterification tank for esterification reaction.

[0112] Transfer the esterification product to the polycondensation tank, add 0.3 parts by weight of nano - titanium dioxide stabilizer into the polycondensation tank for polycondensation reaction, and finally extrude, pelletize, and dry the polymerization melt to obtain the PETG shrink - film functional masterbatch.

[0113] In this comparative example, the intrinsic viscosity of the polycondensation reaction product can reach a maximum of 0.80 dl / g.

[0114] Melt - extrude the prepared PETG shrink - film functional masterbatch, cast film through a die head, perform transverse far - infrared stretching, cooling and shaping, winding, and slitting to make a shrink - film.

[0115] The maximum shrinkage temperature of the prepared film is 120°C, the transverse thermal shrinkage rate in 2 - 3 seconds is 68%, the light transmittance is 89%, and the shrinkage force is 6.8 N / m 2 , and the thickness is 50 μm.

[0116] It can be seen from the comparison of Examples 4 - 6 and Comparative Examples 7 - 9 that based on the functional masterbatch prepared in this application, the shrink - film prepared has relatively excellent shrinkage performance, with a lower shrinkage temperature, stable shrinkage force, and excellent transverse thermal shrinkage rate. Using this shrink - film for the PETG base film of the present utility model can also obtain a washable - coating polyester shrink - film with a lower shrinkage temperature and greater shrinkage force. Tests show that using the shrink - films of Examples 4 - 6 as the PETG base film can all pass the wash test of this application without coating peeling or film rupture.

[0117] Those skilled in the art should understand that although this application is described in the form of multiple embodiments, not every embodiment contains only one independent technical solution. Such narration in the specification is only for clarity. Those skilled in the art should understand the specification as a whole and consider the technical solutions involved in each embodiment as ways that can be combined with each other to form different embodiments to understand the protection scope of this application.

[0118] The above are only illustrative specific embodiments of the present application and are not intended to limit the scope of the present application. Any equivalent changes, modifications and combinations made by those skilled in the art without departing from the concept and principle of the present application shall fall within the scope of protection of the present application.

Claims

1. A washable coated polyester shrink film, characterized in that: The washable coating polyester shrink film is composed of a PETG base film and a washable coating located on at least one side of the PETG base film; the thickness of the PETG base film is 20-50 μm; the thickness of the washable coating is 5-10 μm.

2. A system for preparing the washable coated polyester shrink film according to claim 1, characterized in that: The preparation system includes a first receiving roller for providing a PETG base film, a coating mechanism for forming a water-washable coating on at least one side of the PETG base film is arranged downstream of the first receiving roller, a drying device for drying the water-washable coating is arranged downstream of the coating mechanism, and a second receiving roller is arranged downstream of the drying device; the preparation system further includes a water-washable coating preparation device for providing the water-washable coating to the coating mechanism.

3. The preparation system according to claim 2, characterized in that: The water-washable coating preparation device comprises a first mixing tank for mixing sodium dodecylbenzene sulfonate, 2-hydroxy-4-(3-triethoxysilanepropoxy)benzophenone and ethanol, the outlet of the first mixing tank is connected to a second mixing tank to which polyurethane emulsion, polypropylene emulsion and epoxy resin are added, and the outlet of the second mixing tank is connected to the coating mechanism.

4. The preparation system according to claim 2, characterized in that: The preparation system further includes a functional masterbatch preparation device for preparing a functional masterbatch of PETG shrink film; the outlet of the functional masterbatch preparation device is connected to the inlet of a twin-screw extruder, the outlet of the twin-screw extruder is connected to the inlet of a casting unit, the outlet of the casting unit is connected to the inlet of a stretching mechanism, the outlet of the stretching mechanism is connected to the inlet of a cooling mechanism, and the outlet of the cooling mechanism is connected to the first receiving roller.

5. The preparation system according to claim 4, characterized in that: The functional masterbatch preparation device includes at least one esterification tank and a condensation tank, the esterification tank has a first inlet for terephthalic acid, a second inlet for ethylene glycol, and a third inlet for connecting to the outlet of the esterification auxiliary material tank; the condensation tank has a fourth inlet for connecting to the outlet of the esterification tank, a fifth inlet for connecting to the outlet of the condensation auxiliary material tank, and a sixth inlet for potassium tripolyphosphate; the outlet of the condensation tank is connected to at least one extruder, the outlet of the extruder is connected to a pelletizer, the outlet of the pelletizer is connected to a dryer, and the outlet of the dryer is connected to the inlet of the twin-screw extruder.

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