Low-temperature high-shrinkage PETG shrinkage film and preparation method thereof

Abstract

The invention discloses a low-temperature high-shrinkage PETG shrink film, which adopts a three-layer co-extrusion structure, and comprises a surface layer, a core layer and a bottom layer, the core layer is prepared from a PETG shrink film functional master batch accounting for 90-95 wt% of the total mass and PETG for a common film, and the PETG shrink film functional master batch is prepared from the following raw materials in parts by weight: 100-120 parts of terephthalic acid, 100-120 parts of 1, 2, 4-trimethyl-1, 3-pentanediol monoisobutyrate, 100-120 parts of 1, 2, 4-trimethyl-1, 3-pentanediol monoisobutyrate, 100-120 parts of 1, 2, 4-trimethyl-1, 3-pentanediol The invention relates to a high-temperature-resistant polyurethane adhesive which is prepared from the following components in parts by weight: 30 to 50 parts of 1, 4-cyclohexanedimethanol, 80 to 100 parts of ethylene glycol, 0.1 to 0.2 part of triaryl phosphate, 0.01 to 0.03 part of isocyanate, 0.01 to 0.02 part of potassium tripolyphosphate, 0.1 to 0.2 part of magnesium aluminum silicate, 0.2 to 0.4 part of disodium ethylene diamine tetraacetate and 0.3 to 0.5 part of other auxiliaries. The invention also discloses a preparation method of the shrink film. The transverse thermal shrinkage rate of the PETG shrink film with a three-layer structure prepared by taking the functional master batch as a core layer is greater than 70% at 80 DEG C, and when the PETG shrink film is used as a label of an outer package of a product, the PETG shrink film has relatively good shrink packaging performance on special-shaped bottles, common PP bottles and the like, and the packaging bottles are not easy to damage and deform.

Description

Technical Field

[0001] This application relates to the technical field of packaging materials, and particularly relates to a low-temperature high-shrinkage PETG shrink film and a preparation method thereof. Background Art

[0002] Heat shrinkable films are often used as outer labels on the surfaces of outer packages such as food and beverages. Existing heat shrinkable films have problems such as too high shrinkage temperature and insufficient shrinkage rate, and have poor shrink packaging performance for containers such as special-shaped bottles and PP bottles, and are prone to breakage and deformation, affecting the appearance and use.

[0003] CN 115491000 B discloses a low-temperature high-toughness polyester shrink film for heat shrinkable labels, a preparation method thereof and an application. The raw material composition for preparing the low-temperature high-toughness polyester shrink film includes a polyester composition and an additive. The polyester composition is calculated as 100% by mass, and includes 60% - 70% of ethylene glycol-modified polyethylene terephthalate, 20% - 30% of thermoplastic polyester resin, and 5% - 10% of dicarboxylic acid-modified polyethylene terephthalate; the thermoplastic polyester resin includes polybutylene terephthalate and / or TPEE polyester elastomer; the mass of the additive is 500 ppm - 1500 ppm of the total mass of the polyester composition. The melting temperature of the low-temperature high-toughness polyester shrink film of this prior art is 180 - 190°C, the glass transition temperature is 55 - 60°C, and the heat shrinkage temperature is 60 - 85°C.

[0004] The polyethylene terephthalate in the shrink film of the above prior art contains both 60% - 70% of the raw materials modified with diol and 5% - 10% of the raw materials modified with dicarboxylic acid, and at the same time, 20% - 30% of thermoplastic polyester resin is added, resulting in a mixed composition of the shrink film prepared from these raw materials, and the content of the polyethylene terephthalate component is too low, which is not conducive to recycling this shrink film as a raw material mainly composed of polyethylene terephthalate.

[0005] The previously applied CN 117162618 A by the applicant discloses a recycled heat-shrinkable film and its preparation method. The recycled heat-shrinkable film is composed of an A-layer surface layer, a B-layer core layer, and a C-layer bottom layer formed by extrusion molding. The A layer and the C layer are respectively arranged on both sides of the B layer and are both made of polyester for ordinary films. The B layer is made of recycled materials with 5wt% - 95wt% of the total core layer mass and polyester for ordinary films. The recycled materials are prepared by mixing 60 - 80wt% of polyester recycled particles and 20 - 40wt% of functional masterbatch. The polyester recycled particles are prepared from recycled PET bottles or heat-shrinkable film labels, and the functional masterbatch is composed of a polyester carrier, diethyl phenylphosphonate, sodium dodecylbenzenesulfonate, tridecyl stearate, and magnesium carbonate. This prior art can directly prepare a heat-shrinkable film by melt-modifying the polyester recycled particles by adding a functional masterbatch. Among them, the components of the recycled PET bottles or heat-shrinkable film labels need to meet at least certain purity requirements. If they contain 20% - 30% of thermoplastic polyester resin, plus a large amount of diol and dibasic acid modification components, the content of polyethylene terephthalate in the polyester recycled particles will be too low, which will seriously affect the recycling of shrink labels.

[0006] In addition, CN 113696572 B discloses a composite PETG heat-shrinkable film and its preparation system. The composite PETG heat-shrinkable film is composed of an A-layer surface layer, a B-layer core layer, and a C-layer bottom layer formed by extrusion molding. Among them, both the A layer and the C layer of the surface layer include PETG and 5.5wt% - 9.5wt% of PETG functional masterbatch slices of the total mass. The PETG functional masterbatch slices include 80 - 95 parts by weight of PETG slices, 2 - 5 parts by weight of nano boron nitride, 1 - 2 parts by weight of aluminate, 6 - 10 parts by weight of polydimethylsiloxane, and 2 - 3 parts by weight of potassium chloride. The B layer includes PS and 14.5wt% - 21.5wt% of PS functional masterbatch slices of the total mass.

[0007] The PETG chips used in the PETG functional material of the prior art can be partially or entirely from purchased or pre-prepared raw materials. Of course, as mentioned above, they can also come from recycled PETG labels, etc. The composition of this PETG used as raw material is single and relatively fixed. Therefore, the performance of the PETG functional material prepared therefrom will be restricted by the fixed PETG chips of the raw material. Generally speaking, PETG is generally considered to be a copolymer product obtained by replacing part of ethylene glycol with 1,4-cyclohexanedimethanol (CHDM) during the synthesis of polyethylene terephthalate (PET). The different addition amounts of CHDM determine the crystallinity of the prepared PETG. And PET has a very high crystallinity. Only after the crystallinity is reduced by CHDM modification can relatively good shrinkage performance be obtained. Therefore, when the shrinkage of the shrink film is determined by the amorphous region of the material, there are also significant differences in the shrinkage of PETG obtained by copolymerizing different raw materials. Thus, it is relatively difficult to significantly adjust the shrinkage performance of the functional material prepared from the PETG chips with a specific raw material composition in the above prior art by adding other substance components subsequently.

[0008] For example, the prior art adds nano boron nitride, aluminate, polydimethylsiloxane, and potassium chloride to the PETG chips. Its main adjustment target is to reduce the die head temperature during coextrusion, but relatively speaking, the shrinkage rate is reduced. Although the reduction amplitude is not large, it can still be seen that there are certain limitations in the adjustment amplitude of the shrinkage performance of this functional masterbatch. Summary of the Invention

[0009] The technical problem to be solved by this application is to provide a low-temperature high-shrinkage PETG shrink film and its preparation method to reduce or avoid the problems mentioned above.

[0010] To solve the above technical problem, this application proposes a low-temperature high-shrinkage PETG shrink film, which is a shrink film with a three-layer coextrusion structure, including an A-layer surface layer, a B-layer core layer, and a C-layer bottom layer. The A layer and the C layer are respectively arranged on both sides of the B layer and are both made of ordinary film-use PETG. The B layer is made of a PETG shrink film functional masterbatch accounting for 90wt% - 95wt% of the total mass of the core layer and ordinary film-use PETG. 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 potassium tripolyphosphate, 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.

[0011] Preferably, the other additives are one or a combination of an anti-blocking agent, an antioxidant, a stabilizer, a leveling agent, and a flame retardant.

[0012] Preferably, the thickness of the A layer and the C layer is 1-5 μm, the thickness of the B layer is 38-50 μm, and the total thickness is 40-60 μm.

[0013] Preferably, the thicknesses of the A layer, the B layer, and the C layer are 2-3 μm, 41-44 μm, and 2-3 μm respectively, and the total thickness is 45-50 μm.

[0014] Preferably, the width of the low-temperature high-shrinkage PETG shrink film is 1000-8700 mm.

[0015] Preferably, the width of the low-temperature high-shrinkage PETG shrink film is 1500-5000 mm.

[0016] The present invention also provides a method for preparing the above shrink film, which includes the following steps: mixing the prepared PETG shrink film functional masterbatch chips with ordinary film-grade PETG polyester chips in a uniform manner according to an addition amount of 90 wt% to 95 wt% of the total mass of the core layer, and using it as the core layer raw material; using ordinary film-grade PETG chips as the surface layer and bottom layer raw materials respectively, and through melt co-extrusion, die casting, transverse far-infrared stretching, cooling and shaping, winding, and slitting, a PETG shrink film with an ABC three-layer structure is made.

[0017] Preferably, it further includes the preparation steps of the PETG shrink film functional masterbatch: Add 100-120 parts by weight of terephthalic acid and 80-100 parts by weight of ethylene glycol into the esterification tank, mix evenly at room temperature, and pre-react for 30-60 minutes; then, add 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 that are evenly mixed into the esterification tank; Set the reaction conditions of the esterification tank to 230-250°C and 0.2-0.3 Mpa, carry out the esterification reaction, and after the water output reaches the theoretical value, release the system pressure to atmospheric pressure; Then, filter and transfer the esterification product from the outlet of the esterification tank to the polycondensation tank, and at the same time add 0.01-0.02 parts by weight of potassium tripolyphosphate to the polycondensation tank, keep the temperature at 230-250°C, and stir at atmospheric pressure for 10 minutes; Then evacuate, raise the temperature in the polycondensation tank to 285°C, lower the pressure to below 100 Pa, react for more than 3 hours, the intrinsic viscosity reaches above 0.80 dl / g, lower the temperature to 230°C, and return to atmospheric pressure; Add 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 that are evenly mixed into the polycondensation tank; Keep the temperature in the polycondensation tank at 230°C, stir for 30 minutes, and finally filter, extrude, pelletize, and dry the polymer melt from the outlet of the polycondensation tank to obtain the PETG shrink film functional masterbatch.

[0018] The three-layer structured PETG shrink film prepared with the functional masterbatch of the present invention has a transverse thermal shrinkage rate greater than 70% at 80°C, has a relatively high shrinkage force, and has good shrink packaging performance for special-shaped bottles, ordinary PP bottles, etc. when used as a label for product outer packaging, and it is not easy to cause the packaging bottles to break and deform. Moreover, since both the surface layer and the bottom layer of the film are ordinary PETG, the component content is high, which is conducive to recycling, and the cost of the masterbatch can also be neutralized with ordinary PETG, and the parameter range of the product can be adjusted to facilitate the improvement of the application range of the film of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The following drawings are only intended to illustrate and explain the present application schematically and do not limit the scope of the present application.

[0020] Figure 1 It shows a schematic cross-sectional structure diagram of a low-temperature high-shrink PETG shrink film according to a specific embodiment of the present application. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0021] In order to have 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.

[0022] AsFigure 1 As shown, it shows a schematic cross-sectional structure diagram of a low-temperature high-shrinkage PETG shrink film according to a specific embodiment of the present application. Refer to Figure 1 , the low-temperature high-shrinkage PETG shrink film of the present application is a three-layer co-extrusion structure, including an A-layer surface layer, a B-layer core layer, and a C-layer bottom layer. The A layer and the C layer are respectively arranged on both sides of the B layer and are both made of general film-use PETG, and the B layer is made of PETG shrink film functional masterbatch accounting for 90wt% - 95wt% of the total mass of the core layer and general film-use PETG.

[0023] Among them, the thickness of the A layer and the C layer is 1 - 5μm, the thickness of the B layer is 38 - 50μm, and the total thickness of the three-layer co-extrusion structure of the low-temperature high-shrinkage PETG shrink film is 40 - 60μm. Further preferably, the thicknesses of the A layer, the B layer, and the C layer are 2 - 3μm, 41 - 44μm, and 2 - 3μm respectively, and the total thickness of the low-temperature high-shrinkage PETG shrink film is 45 - 50μm. The width of the low-temperature high-shrinkage PETG shrink film is 1000 - 8700mm, preferably 1500 - 5000mm.

[0024] Among them, the PETG shrink film functional masterbatch in the B layer 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 potassium tripolyphosphate, 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.

[0025] 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.

[0026] The functional masterbatch of the present application can be prepared through the following steps.

[0027] For example, 100 - 120 parts by weight of terephthalic acid and 80 - 100 parts by weight of ethylene glycol can be respectively added to an esterification tank, uniformly mixed at room temperature, and pre-reacted for 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. Set the reaction conditions of the esterification tank to 230 - 250°C, 0.2 - 0.3 Mpa, carry out the esterification reaction, and after the water output reaches the theoretical value, release the system pressure to atmospheric pressure.

[0028] Then, transfer the esterification product from the outlet of the esterification tank to the polycondensation tank by filtration, and at the same time add 0.01 - 0.02 parts by weight of potassium tripolyphosphate to the polycondensation tank. Keep the temperature at 230 - 250 °C and stir at normal pressure for 10 minutes. Then evacuate, raise the temperature in the polycondensation tank to 285 °C, lower the pressure to below 100 Pa, react for more than 3 hours until the intrinsic viscosity reaches 0.80 dl / g or more, and then lower the temperature to 230 °C and return to normal pressure.

[0029] Add 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 to the polycondensation tank after they are uniformly mixed.

[0030] Keep the temperature in the polycondensation tank at 230 °C and stir for 30 minutes. Finally, filter, extrude, pelletize, and dry the polymer melt from the outlet of the polycondensation tank to obtain the PETG shrink film functional masterbatch.

[0031] The low-temperature high-shrink PETG shrink film of this application can be prepared through the following steps.

[0032] For example, slice the prepared PETG shrink film functional masterbatch and mix it uniformly with ordinary film-grade PETG polyester chips at an addition amount of 90 wt% - 95 wt% of the total core layer mass as the core layer raw material; use ordinary film-grade PETG chips as the surface layer and bottom layer raw materials respectively, and through melt co-extrusion, die casting, transverse far-infrared stretching, cooling and shaping, winding, and slitting, make a PETG shrink film with an ABC three-layer structure.

[0033] Example 1

[0034] 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 to the esterification tank for esterification reaction.

[0035] Transfer the esterification product to the 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 to the polycondensation tank for polycondensation reaction.

[0036] In this example, the maximum intrinsic viscosity of the polycondensation reaction product can reach 0.80 dl / g.

[0037] Finally, extrude, pelletize, and dry the polymer melt to obtain the PETG shrink film functional masterbatch.

[0038] The prepared PETG shrink film functional masterbatch is melt-extruded, die-cast into sheets, transversely far-infrared stretched, cooled and shaped, wound up, and slit to produce a single-layer shrink film. The maximum shrinkage temperature of the produced 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.

[0039] Example 2

[0040] The PETG shrink film functional masterbatch slices prepared in Example 1 are uniformly mixed with ordinary film-grade PETG polyester slices at an addition amount of 90 wt% of the total core layer mass, and used as the core layer raw material. Ordinary film-grade PETG slices are used as the surface layer and bottom layer raw materials respectively, and a three-layer ABC structure PETG shrink film is produced through melt co-extrusion, die-casting into sheets, transversely far-infrared stretching, cooling and shaping, winding up, and slitting.

[0041] The thickness of layer A of the produced PETG shrink film is 2 μm, the thickness of layer B is 41 μm, the thickness of layer C is 2 μm, the total thickness is 45 μm, and the width is 3000 mm.

[0042] The maximum shrinkage temperature of the produced PETG shrink film is 83 °C, the transverse thermal shrinkage rate in 2 - 3 seconds is 70%, the light transmittance is 96%, and the shrinkage force is 6.0 N / m 2 .

[0043] Example 3

[0044] 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 are added to the esterification tank for esterification reaction.

[0045] The esterification product is transferred to the polycondensation tank, and 0.015 parts by weight of potassium tripolyphosphate, 0.15 parts by weight of magnesium aluminum silicate, 0.3 parts by weight of disodium ethylenediaminetetraacetate, and 0.4 parts by weight of polytetrahydrofuran leveling agent are added to the polycondensation tank for polycondensation reaction.

[0046] In this example, the intrinsic viscosity of the polycondensation reaction product can reach a maximum of 0.81 dl / g.

[0047] Finally, the polymer melt is extruded, pelletized, and dried to obtain the PETG shrink film functional masterbatch.

[0048] The prepared PETG shrink film functional masterbatch is melt-extruded, die-cast into sheets, transversely far-infrared stretched, cooled and shaped, wound up, and slit to produce a single-layer shrink film. The maximum shrinkage temperature of the produced film is 80 °C, the transverse thermal shrinkage rate in 2 - 3 seconds is 73%, the light transmittance is 94%, and the shrinkage force is 5.8 N / m 2 , and the thickness is 50 μm.

[0049] Example 4

[0050] The PETG shrink film functional masterbatch chips prepared in Example 3 were uniformly mixed with PETG polyester chips for ordinary films at an addition amount of 93 wt% of the total core layer mass, and used as the core layer raw material; the PETG chips for ordinary films were used as the surface layer and bottom layer raw materials respectively, and through melt co-extrusion, die casting, transverse far-infrared stretching, cooling and shaping, winding, and slitting, a PETG shrink film with an ABC three-layer structure was made.

[0051] The thickness of layer A of the prepared PETG shrink film is 3 μm, the thickness of layer B is 44 μm, the thickness of layer C is 3 μm, the total thickness is 50 μm, and the width is 5000 mm.

[0052] The maximum shrinkage temperature of the prepared PETG shrink film is 82 °C, the transverse thermal shrinkage rate in 2 - 3 seconds is 72%, the light transmittance is 95%, and the shrinkage force is 5.9 N / m 2 。

[0053] Example 5

[0054] 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 were added to the esterification tank for esterification reaction.

[0055] The esterification product was transferred to the 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 were added to the polycondensation tank for polycondensation reaction.

[0056] In this example, the intrinsic viscosity of the polycondensation reaction product can reach a maximum of 0.82 dl / g.

[0057] Finally, the polymerization melt was extruded, pelletized, and dried to obtain the PETG shrink film functional masterbatch.

[0058] The prepared PETG shrink film functional masterbatch was melt extruded, die cast, transversely far-infrared stretched, cooled and shaped, wound, and slit to make a single-layer shrink film; the maximum shrinkage temperature of the prepared film is 80 °C, the transverse thermal shrinkage rate in 2 - 3 seconds is 72%, the light transmittance is 93%, and the shrinkage force is 6.2 N / m 2 , and the thickness is 50 μm.

[0059] Example 6

[0060] The PETG shrink film functional masterbatch slices prepared in Example 5 were evenly mixed with the PETG polyester slices for ordinary film in an addition amount of 95wt% of the total mass of the core layer, and used as the core layer raw material; the PETG slices for ordinary film were used as the surface layer and bottom layer raw materials, respectively, and a PETG shrink film with an ABC three-layer structure was made through melt coextrusion, die casting, transverse far-infrared stretching, cooling and shaping, winding, and slitting.

[0061] The thickness of the A layer of the prepared PETG shrink film is 5 μm, the thickness of the B layer is 50 μm, the thickness of the C layer is 5 μm, the total thickness is 60 μm, and the width is 3000 mm.

[0062] The maximum shrinkage temperature of the prepared PETG shrink film is 80°C, the lateral heat shrinkage rate in 2 to 3 seconds is 71%, the light transmittance is 94%, and the shrinkage force is 6.1N / m 2 .

[0063] Based on the limitation of the existing PETG shrink film by the PETG slices with fixed raw materials, the present invention proposes a new preparation process and a combination of specific raw materials based on the raw materials, and improves the shrinkage performance of the prepared PETG by adding different raw material ratios in the esterification and polycondensation stages. The following is a comparison of the performance of the prepared shrink films by different preparation processes and raw material ratios.

[0064] Comparative Example 1

[0065] 100 parts by weight of terephthalic acid, 80 parts by weight of ethylene glycol, and 30 parts by weight of 1,4-cyclohexanedimethanol were added into an esterification tank to carry out an esterification reaction.

[0066] The esterification product is transferred to a polycondensation tank, and 0.3 parts by weight of a nano calcium carbonate anti-adhesive agent is added to the polycondensation tank to carry out a polycondensation reaction. Finally, the polymer melt is extruded, pelletized, and dried to obtain a PETG shrink film functional masterbatch.

[0067] In this comparative example, the maximum intrinsic viscosity of the polycondensation reaction product can reach 0.69 dl / g.

[0068] The prepared PETG shrink film functional masterbatch is melt-extruded, die-cast, transversely far-infrared stretched, cooled and shaped, rolled up, and slit to form a single-layer shrink film; the maximum shrinkage temperature of the film is 120°C, the transverse heat shrinkage rate is 67% in 2 to 3 seconds, the light transmittance is 85%, and the shrinkage force is 6.9N / m 2 , thickness is 50μm.

[0069] The prepared PETG shrink film functional masterbatch slices are uniformly mixed with ordinary film PETG polyester slices at an addition amount of 90 wt% of the total core layer mass, and used as the core layer raw material; the ordinary film PETG slices are used as the surface layer and bottom layer raw materials respectively, and through melt coextrusion, die casting, transverse far-infrared stretching, cooling and shaping, winding, and slitting, a PETG shrink film with an ABC three-layer structure is made.

[0070] The thickness of layer A of the prepared PETG shrink film is 2 μm, the thickness of layer B is 41 μm, the thickness of layer C is 2 μm, the total thickness is 45 μm, and the width is 3000 mm.

[0071] The maximum shrinkage temperature of the prepared PETG shrink film is 125 °C, the transverse thermal shrinkage rate in 2 - 3 seconds is 65%, the light transmittance is 86%, and the shrinkage force is 7.1 N / m 2 。

[0072] Comparative Example 2

[0073] In the esterification tank, 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 are added for esterification reaction.

[0074] The esterification product is transferred to the polycondensation tank, and 0.4 parts by weight of polytetrahydrofuran leveling agent is added to the polycondensation tank for polycondensation reaction. Finally, the polymerization melt is extruded, pelletized, and dried to obtain the PETG shrink film functional masterbatch.

[0075] In this comparative example, the intrinsic viscosity of the polycondensation reaction product can reach a maximum of 0.71 dl / g.

[0076] The prepared PETG shrink film functional masterbatch is melt - extruded, die - cast, transversely far - infrared stretched, cooled and shaped, wound, and slit to make a single - layer shrink film; 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 ,thickness is 50 μm.

[0077] The prepared PETG shrink film functional masterbatch slices are uniformly mixed with ordinary film PETG polyester slices at an addition amount of 93 wt% of the total core layer mass, and used as the core layer raw material; the ordinary film PETG slices are used as the surface layer and bottom layer raw materials respectively, and through melt coextrusion, die casting, transverse far - infrared stretching, cooling and shaping, winding, and slitting, a PETG shrink film with an ABC three - layer structure is made.

[0078] The thickness of layer A of the prepared PETG shrink film is 3 μm, the thickness of layer B is 44 μm, the thickness of layer C is 3 μm, the total thickness is 50 μm, and the width is 5000 mm.

[0079] The maximum shrinkage temperature of the prepared PETG shrink film is 117 °C, the transverse thermal shrinkage rate in 2 - 3 seconds is 70%, the light transmittance is 86%, and the shrinkage force is 6.5 N / m 2 。

[0080] Comparative Example 3

[0081] In the esterification tank, 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 were added for esterification reaction.

[0082] The esterification product was transferred to a polycondensation tank, and 0.3 parts by weight of nano - titanium dioxide stabilizer was added to the polycondensation tank for polycondensation reaction. Finally, the polymer melt was extruded, pelletized, and dried to obtain the PETG shrink film functional masterbatch.

[0083] In this comparative example, the intrinsic viscosity of the polycondensation reaction product can reach a maximum of 0.80 dl / g.

[0084] The prepared PETG shrink film functional masterbatch was melt - extruded, die - cast into sheets, transversely far - infrared stretched, cooled and shaped, wound, and slit to make a single - layer shrink film; 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 ,with a thickness of 50 μm.

[0085] The prepared PETG shrink film functional masterbatch chips were uniformly mixed with ordinary film - used PETG polyester chips according to an addition amount of 95 wt% of the total core layer mass, and used as the core layer raw material; ordinary film - used PETG chips were used as the surface layer and bottom layer raw materials respectively, and a three - layer ABC - structured PETG shrink film was made through melt co - extrusion, die - casting into sheets, transversely far - infrared stretching, cooling and shaping, winding, and slitting.

[0086] The thickness of layer A of the prepared PETG shrink film is 5 μm, the thickness of layer B is 50 μm, the thickness of layer C is 5 μm, the total thickness is 60 μm, and the width is 3000 mm.

[0087] The maximum shrinkage temperature of the prepared PETG shrink film is 124 °C, the transverse thermal shrinkage rate in 2 - 3 seconds is 66%, the light transmittance is 88%, and the shrinkage force is 6.6 N / m 2 。

[0088] Comparative Example 4

[0089] In the esterification tank, 100 parts by weight of terephthalic acid, 80 parts by weight of ethylene glycol, 30 parts by weight of 1,4 - cyclohexanedimethanol, and 0.1 parts by weight of triaryl phosphate were added for esterification reaction.

[0090] 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, and 0.3 part by weight of nano-calcium carbonate anti-caking agent to the polycondensation tank, and carry out polycondensation reaction. Finally, extrude, pelletize, and dry the polymerization melt to obtain the PETG shrink film functional masterbatch.

[0091] In this comparative example, the intrinsic viscosity of the polycondensation reaction product can reach a maximum of 0.75 dl / g.

[0092] 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 single-layer shrink film; the maximum shrinkage temperature of the film made is 120 °C, the transverse thermal shrinkage rate in 2 - 3 seconds is 75%, the light transmittance is 92%, and the shrinkage force is 6.5 N / m 2 , and the thickness is 50 μm.

[0093] Mix the slices of the prepared PETG shrink film functional masterbatch uniformly with ordinary film-grade PETG polyester chips according to the addition amount of 90 wt% of the total core layer mass, and use it as the core layer raw material; use ordinary film-grade PETG chips as the surface layer and bottom layer raw materials respectively, and make a three-layer structure ABC PETG shrink film through melt co-extrusion, die head film casting, transverse far-infrared stretching, cooling and shaping, winding up, and slitting.

[0094] The thickness of layer A of the made PETG shrink film is 2 μm, the thickness of layer B is 41 μm, the thickness of layer C is 2 μm, the total thickness is 45 μm, and the width is 3000 mm.

[0095] The maximum shrinkage temperature of the made PETG shrink film is 123 °C, the transverse thermal shrinkage rate in 2 - 3 seconds is 73%, the light transmittance is 93%, and the shrinkage force is 6.7 N / m 2 .

[0096] Comparative Example 5

[0097] Add 110 parts by weight of terephthalic acid, 90 parts by weight of ethylene glycol, 40 parts by weight of 1,4-cyclohexanedimethanol, and 0.02 part by weight of isocyanate to an esterification tank, and carry out an esterification reaction.

[0098] 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 to the polycondensation tank, and carry out polycondensation reaction. Finally, extrude, pelletize, and dry the polymerization melt to obtain the PETG shrink film functional masterbatch.

[0099] In this comparative example, the intrinsic viscosity of the polycondensation reaction product can reach a maximum of 0.73 dl / g.

[0100] The prepared PETG shrink film functional masterbatch is melt-extruded, die-cast into sheets, transversely far-infrared stretched, cooled and shaped, wound up, and slit to produce a single-layer shrink film; the maximum shrinkage temperature of the produced film is 108 °C, the transverse thermal shrinkage rate in 2 - 3 seconds is 76%, the light transmittance is 90%, and the shrinkage force is 6.5 N / m 2 , and the thickness is 50 μm.

[0101] The prepared PETG shrink film functional masterbatch chips are uniformly mixed with PETG polyester chips for ordinary films at an addition amount of 93 wt% of the total core layer mass, and used as the core layer raw material; the PETG chips for ordinary films are used as the surface layer and bottom layer raw materials respectively, and a three-layer structure PETG shrink film of ABC is produced through melt coextrusion, die-cast into sheets, transversely far-infrared stretched, cooled and shaped, wound up, and slit.

[0102] For the produced PETG shrink film, the thickness of layer A is 3 μm, the thickness of layer B is 44 μm, the thickness of layer C is 3 μm, the total thickness is 50 μm, and the width is 5000 mm.

[0103] The maximum shrinkage temperature of the produced PETG shrink film is 110 °C, the transverse thermal shrinkage rate in 2 - 3 seconds is 77%, the light transmittance is 91%, and the shrinkage force is 6.6 N / m 2 .

[0104] Comparative Example 6

[0105] 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.

[0106] The esterification product is transferred to a polycondensation tank, and 0.02 parts by weight of potassium tripolyphosphate, 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. Finally, the polymer melt is extruded, pelletized, and dried 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 0.80 dl / g.

[0108] The prepared PETG shrink film functional masterbatch is melt-extruded, die-cast into sheets, transversely far-infrared stretched, cooled and shaped, wound up, and slit to produce a single-layer shrink film; the maximum shrinkage temperature of the produced film is 109 °C, the transverse thermal shrinkage rate in 2 - 3 seconds is 75%, the light transmittance is 84%, and the shrinkage force is 7.9 N / m 2 , and the thickness is 50 μm.

[0109] The prepared PETG shrink film functional masterbatch slices were uniformly mixed with ordinary film-grade PETG polyester slices at an addition amount of 95 wt% of the total core layer mass, and used as the core layer raw material; the ordinary film-grade PETG slices were used as the surface layer and bottom layer raw materials respectively, and through melt co-extrusion, die casting, transverse far-infrared stretching, cooling and shaping, winding, and slitting, a PETG shrink film with an ABC three-layer structure was made.

[0110] The thickness of layer A of the prepared PETG shrink film is 5 μm, the thickness of layer B is 50 μm, the thickness of layer C is 5 μm, the total thickness is 60 μm, and the width is 3000 mm.

[0111] The maximum shrinkage temperature of the prepared PETG shrink film is 108 °C, the transverse heat shrinkage rate in 2 - 3 seconds is 77%, the light transmittance is 86%, and the shrinkage force is 7.6 N / m. 2 。

[0112] It can be seen from the comparison between the above-mentioned examples and comparative examples that the single-layer shrink film prepared with the functional masterbatch obtained by the method of the present invention has relatively excellent shrinkage performance, with a lower shrinkage temperature and excellent transverse heat shrinkage rate. The transverse heat shrinkage rate of the three-layer structure PETG shrink film prepared with the functional masterbatch of the present invention as the core layer is greater than 70% at 80 °C, and at the same time has a higher shrinkage force. When used as a label for product outer packaging, it has good shrink packaging performance for special-shaped bottles, ordinary PP bottles, etc., and is not easy to cause the packaging bottles to be damaged or deformed. Moreover, since both the surface layer and the bottom layer of the film are ordinary PETG, with a high component content, it is conducive to recycling, and the cost of the masterbatch can also be neutralized with ordinary PETG to adjust the parameter range of the product, so as to be conducive to expanding the application range of the film of the present invention.

[0113] Those skilled in the art should understand that although this application is described in the form of multiple embodiments, not every embodiment only contains an 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 regard 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.

[0114] The above are only the schematic specific embodiments of this application, and are not intended to limit the scope of this application. Any equivalent changes, modifications, and combinations made by those skilled in the art without departing from the concept and principles of this application shall fall within the protection scope of this application.

Claims

1. A low-temperature high-shrinkage PETG shrink film, which is a shrink film with a three-layer co-extruded structure, comprising a surface layer A, a core layer B and a bottom layer C, wherein the A layer and the C layer are respectively arranged on both sides of the B layer and are both made of PETG for ordinary film, and the B layer is made of PETG shrink film functional masterbatch of 90wt% to 95wt% of the total mass of the core layer and PETG for ordinary film, wherein: 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 potassium tripolyphosphate, 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.

2. The shrink film according to claim 1, characterized in that The other auxiliary agent is one or a combination of an anti-adhesive agent, an antioxidant, a stabilizer, a leveling agent, and a flame retardant.

3. The shrink film according to claim 1, characterized in that The thickness of the A layer and the C layer is 1-5 μm, the thickness of the B layer is 38-50 μm, and the total thickness is 40-60 μm.

4. The shrink film according to claim 1, characterized in that The thicknesses of the A layer, the B layer and the C layer are 2-3 μm, 41-44 μm and 2-3 μm respectively, and the total thickness is 45-50 μm.

5. The shrink film according to claim 1, characterized in that: The width of the low-temperature high-shrinkage PETG shrink film is 1000-8700 mm.

6. The shrink film according to claim 1, characterized in that The width of the low-temperature high-shrinkage PETG shrink film is 1500-5000mm.

7. The method for preparing a shrink film according to any one of claims 1 to 6, comprising the following steps: uniformly mixing the prepared PETG shrink film functional masterbatch slices with PETG polyester slices for common film in an amount of 90wt% to 95wt% of the total mass of the core layer, and using the slices as the core layer raw material; using the PETG slices for common film as the surface layer and bottom layer raw materials, respectively, and preparing a PETG shrink film with an ABC three-layer structure through melt coextrusion, die casting, lateral far-infrared stretching, cooling and shaping, winding, and slitting.

8. The method for preparing a shrink film as claimed in claim 7, further comprising the step of preparing a PETG shrink film functional masterbatch: Add 100-120 parts by weight of terephthalic acid and 80-100 parts by weight of ethylene glycol into an esterification tank, mix them evenly at room temperature, and pre-react for 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, and the esterification reaction is carried out. After the water output reaches the theoretical value, the system pressure is released to normal pressure; Then, the esterification product is filtered and transferred from the outlet of the esterification tank to the polycondensation tank, and 0.01-0.02 parts by weight of potassium tripolyphosphate is added to the polycondensation tank, the temperature is maintained at 230-250° C., and the mixture is stirred at normal pressure for 10 minutes; then, vacuum is drawn, the temperature in the polycondensation tank is raised to 285° C., the pressure is reduced to below 100 Pa, the reaction is carried out for more than 3 hours, the intrinsic viscosity reaches more than 0.80 dl / g, the temperature is reduced to 230° C., and the mixture is returned to normal pressure; Add 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, into the polycondensation tank; The temperature in the polycondensation tank was maintained at 230° C. and stirred for 30 minutes. Finally, the polymer melt was filtered, extruded, pelletized, and dried from the outlet of the polycondensation tank to obtain a PETG shrink film functional masterbatch.

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