Polyester transparent low-shrinkage shrink film and preparation method thereof

Abstract

The invention discloses a polyester transparent low-shrinkage shrink film which is prepared from PETG shrink film functional master batch slices, PET slices for common films, polyvinyl butyral and butylated hydroxytoluene, the total weight of the PETG shrink film functional master batch slices, the PET slices for common films, the polyvinyl butyral and the butylated hydroxytoluene is 100 wt%, and the total weight of the PETG shrink film functional master batch slices, the PET slices for common films, the polyvinyl butyral and the butylated hydroxytoluene is 100 wt%. The addition amount of the PETG shrink film functional master batch slice is 75-85 wt%, the addition amount of the polyvinyl butyral is 5-8 wt%, the addition amount of the butylated hydroxytoluene is 3-5 wt%, and the balance is the PET slice for the common film. By providing the high-performance functional master batch and adding the polyvinyl butyral and the butylated hydroxytoluene on the basis of the functional master batch, the low-shrinkage shrink film can be prepared, and relatively, the process is simpler, the adaptability is wider, and the cost is lower.

Description

Technical Field

[0001] This application relates to the field of packaging technology, and particularly to a polyester transparent low-shrinkage shrink film and a preparation method thereof. Background Art

[0002] Shrink film is a commonly used packaging material, widely used in the packaging of various foods, beverages, daily chemical products, etc. Its main feature is that it can shrink under conditions such as heating or freezing, forming a tightly fitting packaging effect with the packaged item. Different types of shrink films have their unique application scenarios in different product packagings. When using shrink film, it is necessary to select according to requirements such as the nature of the packaged item, the shape of the packaging, and the packaging effect to be achieved, so as to achieve the best use effect on the premise of ensuring freshness preservation, aesthetics, and convenience.

[0003] For example, when the item to be packaged has specific requirements for the shrinkage rate of the shrink film, or when it is necessary to store the shrink film at room temperature, a shrink film with a low shrinkage rate needs to be selected. Shrink films with a low shrinkage rate are usually suitable for the following situations:

[0004] Room temperature storage: Since shrink films with a low shrinkage rate have the characteristic of a low natural shrinkage rate at room temperature, they can be stored in an environment with a room temperature below 25°C without worrying about being difficult to unfold or the label being deformed.

[0005] Specific packaging requirements: For certain specific packaging requirements, such as the need to keep the packaging flat or avoid packaging deformation caused by excessive shrinkage, a shrink film with a low shrinkage rate is a more suitable choice. For example, POF low-temperature shrink film has a low shrinkage temperature and a low shrinkage rate, and is suitable for achieving an ideal shrinkage rate at a temperature of 80 - 100°C.

[0006] Environmental protection considerations: In some cases, choosing a shrink film with a low shrinkage rate is also for environmental protection considerations. For example, the recyclable, recyclable, energy-saving, and environmentally friendly PETG shrink film, even if recyclable raw materials are added during the production process, has the same performance as conventional PETG shrink film, and is widely applicable to the sleeve labels of various bottle types, especially special-shaped bottles, which is beneficial to environmental friendliness.

[0007] Printing and design freedom: For product packagings that require high-quality printing and design freedom, shrink films with a low shrinkage rate can provide better support. High transparency and excellent printing performance can strengthen the brand recognition of the bottle body label. Printing from the inside will not cause the label to fade or break due to friction, and a 360-degree overall label design integrating multiple colors and high-quality printing can be made.

[0008] In summary, shrink films with a low shrinkage rate have important application values in aspects such as room temperature storage, specific packaging requirements, environmental protection considerations, and printing and design freedom.

[0009] The commonly used existing POF shrink film is a multi-layer co-extruded polyolefin thermal film. In the ordinary type, LLDPE is used in the middle layer, and polypropylene (PP) is used in the inner and outer layers. It is made by co-extruding three or more layers and then through a special double-bubble synchronous biaxial stretching process. The POF shrink film has the advantages of high gloss, good toughness, high tear strength, etc. However, it also has defects such as too high production cost, sensitivity to high-temperature environment, uneven shrinkage rate, easy tearing and foaming. In addition, the film layers with different components also have the disadvantages of complex raw materials and difficulty in recycling.

[0010] The commonly used existing PETG shrink film has the advantages of high ultimate shrinkage rate, low natural shrinkage rate, flat shrinkage curve, high transparency and gloss, excellent printing color, and good environmental compatibility. However, its too high shrinkage rate makes it not suitable as a low-shrinkage material for packaging specific products.

[0011] For example, CN 113696572 B discloses a composite PETG heat shrink film and its preparation system. The composite PETG heat shrink 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 PETG functional masterbatch chips with a total weight of 5.5wt% - 9.5wt%. The PETG functional masterbatch chips include 80 - 95 parts by weight of PETG chips, 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 PS functional masterbatch chips with a total weight of 14.5wt% - 21.5wt%.

[0012] The PETG chips used in the PETG functional masterbatch of this prior art can be partially or wholly from purchased or pre-prepared raw materials. Of course, they can also come from PETG label recycling materials, etc. The components of the PETG used as raw materials are single and relatively fixed. Therefore, the performance of the PETG functional masterbatch prepared from it will be limited by the fixed PETG chips of the raw materials. For example, the shrinkage rate is maintained within a specific range. For example, in this prior art, nano boron nitride, aluminate, polydimethylsiloxane, and potassium chloride are added to the PETG chips. Its main adjustment target is to reduce the die head temperature during co-extrusion, but it can only slightly reduce the shrinkage rate and it is difficult to prepare a low-shrinkage shrink film. Summary of the Invention

[0013] The technical problem to be solved by this application is to provide a polyester transparent low-shrinkage shrink film and its preparation method to reduce or avoid the problems mentioned above.

[0014] To solve the above technical problems, the present application provides a polyester transparent low-shrinkage shrink film, which is made of PETG shrink film functional masterbatch chips, PET chips for ordinary films, polyvinyl butyral, and butylated hydroxytoluene. Among them, the total weight of the PETG shrink film functional masterbatch chips, PET chips for ordinary films, polyvinyl butyral, and butylated hydroxytoluene is 100 wt%, the addition amount of the PETG shrink film functional masterbatch chips is 75 wt% - 85 wt%, the addition amount of polyvinyl butyral is 5 wt% - 8 wt%, the addition amount of butylated hydroxytoluene is 3 wt% - 5 wt%, and the rest is PET chips for ordinary films; 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.

[0015] 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.

[0016] The present invention also provides a method for preparing the above shrink film, which includes the following steps: uniformly mixing the prepared PETG shrink film functional masterbatch with PET chips for ordinary films, polyvinyl butyral, and butylated hydroxytoluene to form a mixture, melting and extruding the mixture, casting the film through a die, performing transverse far-infrared stretching, cooling and shaping, winding, and slitting to produce the shrink film; among them, the total weight of the PETG shrink film functional masterbatch chips, PET chips for ordinary films, polyvinyl butyral, and butylated hydroxytoluene is 100 wt%, the addition amount of the PETG shrink film functional masterbatch chips is 75 wt% - 85 wt%, the addition amount of polyvinyl butyral is 5 wt% - 8 wt%, the addition amount of butylated hydroxytoluene is 3 wt% - 5 wt%, and the rest is PET chips for ordinary films.

[0017] Preferably, it further includes the preparation steps of 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, uniformly mix 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 uniformly mixed well into the esterification tank; set the reaction conditions of the esterification tank as 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, reduce the pressure to below 100 Pa, react for more than 3 hours, and the intrinsic viscosity reaches above 0.80 dl / g, then reduce the temperature to 230°C and restore 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 uniformly mixed well 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 polymerization melt from the outlet of the polycondensation tank to obtain the PETG shrink film functional masterbatch.

[0018] The present invention provides a high-performance functional masterbatch. On the basis of this functional masterbatch, by adding polyvinyl butyral and butylated hydroxytoluene, a low-shrinkage shrink film can be prepared. Relatively speaking, the process is simpler, the adaptability is wider, and the cost is lower. Detailed implementation manners

[0019] In order to have a clearer understanding of the technical features, purposes, and effects of the present application, the specific implementation manners of the present application will be described in detail below.

[0020] The present invention provides a polyester transparent low-shrinkage shrink film, which is made of PETG shrink film functional masterbatch chips, PET chips for ordinary films, polyvinyl butyral, and butylated hydroxytoluene.

[0021] 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.

[0022] Among them, other additives include but are not limited to one or a combination of anti-adhesives, antioxidants, stabilizers, leveling agents, flame retardants, etc.

[0023] In the shrink film of the present invention, a functional masterbatch with relatively high shrinkage performance is adopted. When it needs to be applied to some scenarios with relatively low parameter requirements, the shrinkage parameters can be reduced by subsequently adding polyvinyl butyral and butylated hydroxytoluene. Therefore, in the case of having a functional masterbatch with a wider applicability, it is relatively easy to obtain the polyester transparent low-shrinkage shrink film of the present invention.

[0024] The PETG shrink film functional masterbatch of the present application can be prepared through the following steps.

[0025] For example, 100-120 parts by weight of terephthalic acid and 80-100 parts by weight of ethylene glycol can be respectively added into an esterification tank, uniformly mixed at normal 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 are added to the esterification tank. The reaction conditions of the esterification tank are set at 230-250 °C and 0.2-0.3 Mpa for esterification reaction. After the water output reaches the theoretical value, the system pressure is released to atmospheric pressure.

[0026] 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 potassium tripolyphosphate is added to the polycondensation tank. 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 above 0.80 dl / g. The temperature is then lowered to 230 °C and returned to atmospheric pressure.

[0027] 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.

[0028] 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.

[0029] The polyester transparent low-shrinkage shrink film of the present application can be prepared through the following steps.

[0030] For example, the prepared PETG shrink film functional masterbatch is uniformly mixed with PET chips for ordinary films, polyvinyl butyral, and butylated hydroxytoluene to form a mixture. The mixture is melt-extruded, die-cast into sheets, transversely far-infrared stretched, cooled and shaped, wound up, and slit to produce the shrink film.

[0031] Example 1

[0032] 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 for esterification reaction.

[0033] 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-caking agent into the polycondensation tank for polycondensation reaction.

[0034] In this example, the intrinsic viscosity of the polycondensation reaction product can reach a maximum of 0.80 dl / g.

[0035] Finally, extrude, pelletize, and dry the polymerization melt to obtain the PETG shrink film functional masterbatch.

[0036] Melt-extrude, die-cast into sheets, transversely far-infrared stretch, cool and shape, wind up, and slit the prepared PETG shrink film functional masterbatch to produce a shrink film.

[0037] 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.

[0038] Example 2

[0039] Uniformly mix the PETG shrink film functional masterbatch prepared in Example 1 with PET chips for ordinary films, polyvinyl butyral, and butylated hydroxytoluene to form a mixture. Melt-extrude, die-cast into sheets, transversely far-infrared stretch, cool and shape, wind up, and slit the mixture to produce the shrink film.

[0040] Among them, the total weight of the PETG shrink film functional masterbatch chips, PET chips for ordinary films, polyvinyl butyral, and butylated hydroxytoluene is 100 wt%, the addition amount of the PETG shrink film functional masterbatch chips is 75 wt%, the addition amount of polyvinyl butyral is 5 wt%, the addition amount of butylated hydroxytoluene is 3 wt%, and the rest is PET chips for ordinary films.

[0041] The maximum shrinkage temperature of the produced shrink film is 101°C, the transverse heat shrinkage rate in 2 - 3 seconds is 33%, the light transmittance is 96%, and the shrinkage force is 5.8 N / m 2 。

[0042] Example 3

[0043] 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 into the esterification tank for esterification reaction.

[0044] Transfer the esterification product to the polycondensation tank, and add 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 into the polycondensation tank for polycondensation reaction.

[0045] In this example, the intrinsic viscosity of the polycondensation reaction product can reach a maximum of 0.81 dl / g.

[0046] Finally, extrude, pelletize, and dry the polymer melt to obtain the PETG shrink film functional masterbatch.

[0047] Melt - extrude the prepared PETG shrink film functional masterbatch, cast film through the die head, perform transverse far - infrared stretching, cooling and shaping, winding, and slitting to make the shrink film.

[0048] The maximum shrinkage temperature of the produced film is 80°C, the transverse heat shrinkage rate in 2 - 3 seconds is 73%, the light transmittance is 94%, the shrinkage force is 5.8 N / m 2 , and the thickness is 50 μm.

[0049] Example 4

[0050] Uniformly mix the PETG shrink film functional masterbatch prepared in Example 3 with PET chips for ordinary films, polyvinyl butyral, and butylated hydroxytoluene to form a mixture, and then melt - extrude, cast film through the die head, perform transverse far - infrared stretching, cooling and shaping, winding, and slitting the mixture to make the shrink film.

[0051] Among them, the total weight of the PETG shrink film functional masterbatch chips, PET chips for ordinary films, polyvinyl butyral, and butylated hydroxytoluene is 100 wt%, the addition amount of the PETG shrink film functional masterbatch chips is 80 wt%, the addition amount of polyvinyl butyral is 7 wt%, the addition amount of butylated hydroxytoluene is 4 wt%, and the rest is PET chips for ordinary films.

[0052] The maximum shrinkage temperature of the produced shrink film is 98°C, the transverse heat shrinkage rate in 2 - 3 seconds is 35%, the light transmittance is 95%, and the shrinkage force is 5.6 N / m 2 。

[0053] Example 5

[0054] 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, and carry out the esterification reaction.

[0055] Transfer the esterification product to the polycondensation tank, and in the polycondensation tank, add 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, and carry out the 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, extrude, pelletize, and dry the polymer melt to obtain the PETG shrink film functional masterbatch.

[0058] Melt - extrude the prepared PETG shrink film functional masterbatch, cast film through a die, perform transverse far - infrared stretching, cooling and shaping, winding, and slitting to make a shrink film.

[0059] 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.

[0060] Example 6

[0061] Uniformly mix the PETG shrink film functional masterbatch prepared in Example 5 with ordinary film - used PET chips, polyvinyl butyral, and butylated hydroxytoluene to form a mixture, and melt - extrude, cast film through a die, perform transverse far - infrared stretching, cooling and shaping, winding, and slitting the mixture to make the shrink film.

[0062] Among them, the total weight of the PETG shrink film functional masterbatch chips, ordinary film - used PET chips, polyvinyl butyral, and butylated hydroxytoluene is 100 wt%, the addition amount of the PETG shrink film functional masterbatch chips is 85 wt%, the addition amount of polyvinyl butyral is 8 wt%, the addition amount of butylated hydroxytoluene is 5 wt%, and the rest is ordinary film - used PET chips.

[0063] The maximum shrinkage temperature of the prepared shrink film is 97 °C, the transverse thermal shrinkage rate in 2 - 3 seconds is 37%, the light transmittance is 94%, and the shrinkage force is 5.5 N / m 2 .

[0064] The functional masterbatch of the present invention proposes a new preparation process and a combination of specific raw materials starting from the raw materials. By adding different raw material ratios separately in the esterification and polycondensation stages, the shrinkage performance of the prepared shrink film can be improved. Based on the prepared functional masterbatch, a low-shrinkage transparent shrink film can be obtained by adding polyvinyl butyral and butylated hydroxytoluene. The following is a comparative example, in which the performance of the prepared shrink film is compared with different preparation processes and raw material ratios.

[0065] Comparative Example 1

[0066] In an esterification tank, 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 for esterification reaction.

[0067] The esterification product was transferred to a polycondensation tank, and 0.3 parts by weight of nano calcium carbonate anti-bonding agent was added to the polycondensation tank for polycondensation reaction. Finally, the polymerized melt was extruded, pelletized, and dried to obtain a PETG shrink film functional masterbatch.

[0068] In this comparative example, the intrinsic viscosity of the polycondensation reaction product can reach a maximum of 0.69 dl / g.

[0069] The prepared PETG shrink film functional masterbatch was melt-extruded, die-cast into sheets, transversely far-infrared stretched, cooled and shaped, wound up, and slit to make a shrink film.

[0070] 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.

[0071] The prepared PETG shrink film functional masterbatch was uniformly mixed with ordinary film PET chips, polyvinyl butyral, and butylated hydroxytoluene to form a mixture, and the mixture was melt-extruded, die-cast into sheets, transversely far-infrared stretched, cooled and shaped, wound up, and slit to make the shrink film.

[0072] Among them, the total weight of the PETG shrink film functional masterbatch chips, ordinary film PET chips, polyvinyl butyral, and butylated hydroxytoluene is 100 wt%, the addition amount of the PETG shrink film functional masterbatch chips is 75 wt%, the addition amount of polyvinyl butyral is 5 wt%, the addition amount of butylated hydroxytoluene is 3 wt%, and the rest is ordinary film PET chips.

[0073] The maximum shrinkage temperature of the prepared shrink film is 122 °C, the transverse thermal shrinkage rate in 2 - 3 seconds is 54%, the light transmittance is 96%, and the shrinkage force is 5.1 N / m 2 .

[0074] Comparative Example 2

[0075] 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 into the esterification tank, and carry out the esterification reaction.

[0076] Transfer the esterification product to the polycondensation tank, add 0.4 parts by weight of polytetrahydrofuran leveling agent into the polycondensation tank, carry out the polycondensation reaction, and finally extrude, pelletize, and dry the polymer melt to obtain the PETG shrink film functional masterbatch.

[0077] In this comparative example, the intrinsic viscosity of the polycondensation reaction product can reach a maximum of 0.71 dl / g.

[0078] Melt-extrude the prepared PETG shrink film functional masterbatch, cast film with a die head, stretch it transversely by far-infrared, cool and shape it, wind it up, and slit it to make a shrink film.

[0079] 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.

[0080] Uniformly mix the prepared PETG shrink film functional masterbatch with PET chips for ordinary films, polyvinyl butyral, and butylated hydroxytoluene to form a mixture, melt-extrude the mixture, cast film with a die head, stretch it transversely by far-infrared, cool and shape it, wind it up, and slit it to make the shrink film.

[0081] Among them, the total weight of the PETG shrink film functional masterbatch chips, PET chips for ordinary films, polyvinyl butyral, and butylated hydroxytoluene is 100 wt%, the addition amount of the PETG shrink film functional masterbatch chips is 80 wt%, the addition amount of polyvinyl butyral is 7 wt%, the addition amount of butylated hydroxytoluene is 4 wt%, and the rest is PET chips for ordinary films.

[0082] The maximum shrinkage temperature of the prepared PETG shrink film is 127 °C, the transverse thermal shrinkage rate in 2 - 3 seconds is 51%, the light transmittance is 95%, and the shrinkage force is 5.5 N / m 2 .

[0083] Comparative Example 3

[0084] 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, and carry out the esterification reaction.

[0085] Transfer the esterification product to a polycondensation tank, add 0.3 parts by weight of nano-titanium dioxide stabilizer to the polycondensation tank, carry out polycondensation reaction, and finally extrude, pelletize and dry the polymer melt to obtain the PETG shrink film functional masterbatch.

[0086] In this comparative example, the intrinsic viscosity of the polycondensation reaction product can reach a maximum of 0.80 dl / g.

[0087] 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 shrink film.

[0088] 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.

[0089] Uniformly mix the prepared PETG shrink film functional masterbatch with PET chips for ordinary films, polyvinyl butyral, and butylated hydroxytoluene to form a mixture, melt-extrude the mixture, cast film with a die head, stretch transversely by far-infrared, cool and shape, wind up, and slit to make the shrink film.

[0090] Among them, the total weight of the PETG shrink film functional masterbatch chips, PET chips for ordinary films, polyvinyl butyral, and butylated hydroxytoluene is 100 wt%, the addition amount of the PETG shrink film functional masterbatch chips is 85 wt%, the addition amount of polyvinyl butyral is 8 wt%, the addition amount of butylated hydroxytoluene is 5 wt%, and the rest is PET chips for ordinary films.

[0091] The maximum shrinkage temperature of the prepared shrink film is 124 °C, the transverse thermal shrinkage rate in 2 - 3 seconds is 55%, the light transmittance is 96%, and the shrinkage force is 5.3 N / m 2 .

[0092] Comparative Example 4

[0093] Add 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 part by weight of triaryl phosphate to an esterification tank for esterification reaction.

[0094] Transfer the esterification product to a polycondensation tank, 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 for polycondensation reaction, and finally extrude, pelletize and dry the polymer melt to obtain the PETG shrink film functional masterbatch.

[0095] In this comparative example, the intrinsic viscosity of the polycondensation reaction product can reach a maximum of 0.75 dl / g.

[0096] 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 shrink film.

[0097] The maximum shrinkage temperature of the produced film 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.

[0098] The prepared PETG shrink film functional masterbatch is uniformly mixed with PET chips for ordinary films, polyvinyl butyral, and butylated hydroxytoluene to form a mixture, and the mixture is melt-extruded, die-cast into sheets, transversely far-infrared stretched, cooled and shaped, wound up, and slit to produce the shrink film.

[0099] Among them, the total weight of the PETG shrink film functional masterbatch chips, PET chips for ordinary films, polyvinyl butyral, and butylated hydroxytoluene is 100 wt%, the addition amount of the PETG shrink film functional masterbatch chips is 75 wt%, the addition amount of polyvinyl butyral is 5 wt%, the addition amount of butylated hydroxytoluene is 3 wt%, and the rest is PET chips for ordinary films.

[0100] The maximum shrinkage temperature of the produced shrink film is 123 °C, the transverse thermal shrinkage rate in 2 - 3 seconds is 56%, the light transmittance is 94%, and the shrinkage force is 5.5 N / m 2 .

[0101] Comparative Example 5

[0102] 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 parts by weight of isocyanate are added to an esterification tank for esterification reaction.

[0103] The esterification product is transferred to a 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 a polytetrahydrofuran leveling agent 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.

[0104] In this comparative example, the intrinsic viscosity of the polycondensation reaction product can reach a maximum of 0.73 dl / g.

[0105] 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 shrink film.

[0106] 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.

[0107] The prepared PETG shrink film functional masterbatch is uniformly mixed with PET chips for ordinary films, polyvinyl butyral, and butylated hydroxytoluene to form a mixture. The mixture is melt-extruded, cast into a film through a die, transversely stretched by far-infrared rays, cooled and shaped, wound up, and slit to produce the shrink film.

[0108] Among them, the total weight of the PETG shrink film functional masterbatch chips, PET chips for ordinary films, polyvinyl butyral, and butylated hydroxytoluene is 100 wt%, the addition amount of the PETG shrink film functional masterbatch chips is 80 wt%, the addition amount of polyvinyl butyral is 7 wt%, the addition amount of butylated hydroxytoluene is 4 wt%, and the rest is PET chips for ordinary films.

[0109] The maximum shrinkage temperature of the prepared PETG shrink film is 120 °C, the transverse heat shrinkage rate in 2 - 3 seconds is 57%, the light transmittance is 92%, and the shrinkage force is 5.3 N / m 2 。

[0110] Comparative Example 6

[0111] 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.

[0112] 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.

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

[0114] The prepared PETG shrink film functional masterbatch is melt - extruded, cast into a film through a die, transversely stretched by far - infrared rays, cooled and shaped, wound up, and slit to produce a shrink film.

[0115] The maximum shrinkage temperature of the produced film is 109 °C, the transverse heat shrinkage rate in 2 - 3 seconds is 75%, the light transmittance is 84%, the shrinkage force is 7.9 N / m 2 , and the thickness is 50 μm.

[0116] The prepared PETG shrink film functional masterbatch is uniformly mixed with PET chips for ordinary films, polyvinyl butyral, and butylated hydroxytoluene to form a mixture. The mixture is melt - extruded, cast into a film through a die, transversely stretched by far - infrared rays, cooled and shaped, wound up, and slit to produce the shrink film.

[0117] Among them, the total weight of the PETG shrink film functional masterbatch chips, PET chips for ordinary films, polyvinyl butyral, and butylated hydroxytoluene is 100 wt%, the addition amount of the PETG shrink film functional masterbatch chips is 85 wt%, the addition amount of polyvinyl butyral is 8 wt%, the addition amount of butylated hydroxytoluene is 5 wt%, and the rest is PET chips for ordinary films.

[0118] The maximum shrinkage temperature of the prepared shrink film is 118 °C, the transverse heat shrinkage rate in 2 - 3 seconds is 59%, the light transmittance is 93%, and the shrinkage force is 5.6 N / m 2 。

[0119] 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. Based on the functional masterbatch of the present invention, by adding polyvinyl butyral and butylated hydroxytoluene, a low - shrinkage shrink film can be prepared, which is relatively simpler in process, has a wider adaptability, and lower cost.

[0120] 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 a description 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.

[0121] The above - mentioned are only the illustrative specific embodiments of this application, and are not used 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 scope of protection of this application.

Claims

1. A polyester transparent low-shrinkage shrink film, made from PETG shrink film functional masterbatch slices, PET slices for ordinary films, polyvinyl butyral and butylated hydroxytoluene, wherein: The total weight of the PETG shrink film functional masterbatch slices, the PET slices for ordinary films, polyvinyl butyral and butylated hydroxytoluene is 100wt%, the addition amount of the PETG shrink film functional masterbatch slices is 75wt% to 85wt%, the addition amount of polyvinyl butyral is 5wt% to 8wt%, the addition amount of butylated hydroxytoluene is 3wt% to 5wt%, and the rest is PET slices for ordinary films; wherein the PETG shrink film functional masterbatch is composed of the following weights: The invention is prepared from the following raw materials in appropriate weight parts: 100-120 weight parts of terephthalic acid, 30-50 weight parts of 1,4-cyclohexanedimethanol, 80-100 weight parts of ethylene glycol, 0.1-0.2 weight parts of triaryl phosphate, 0.01-0.03 weight parts of isocyanate, 0.01-0.02 weight parts of potassium tripolyphosphate, 0.1-0.2 weight parts of magnesium aluminum silicate, 0.2-0.4 weight parts of disodium ethylenediaminetetraacetate and 0.3-0.5 weight parts 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 method for preparing a shrink film according to any one of claims 1 to 2, comprising the following steps: uniformly mixing the prepared PETG shrink film functional masterbatch with PET slices for ordinary films, polyvinyl butyral and butylated hydroxytoluene to form a mixture, and melt-extruding the mixture, die casting, transverse far-infrared stretching, cooling and shaping, winding, and slitting to prepare the shrink film; wherein, The total weight of the PETG shrink film functional masterbatch slices, the PET slices for common films, polyvinyl butyral and butylated hydroxytoluene is 100wt%, the added amount of the PETG shrink film functional masterbatch slices is 75wt%-85wt%, the added amount of polyvinyl butyral is 5wt%-8wt%, the added amount of butylated hydroxytoluene is 3wt%-5wt%, and the rest are PET slices for common films.

4. The method for preparing a shrink film as claimed in claim 3, 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.