Polyester heat shrinkable film with easy recycling process

Abstract

A heat-shrinkable film in which the slope of the linear regression curve of the separation rate according to G-force is controlled within a specific range when the film flakes are mixed with PET flakes and subjected to heat treatment followed by centrifugation can exhibit excellent recyclability under various conditions, and the recyclability of the film can be quantitatively controlled across a range of conditions compared to conventional heat-shrinkable films.

Description

Polyester heat-shrinkable film with easy recycling process

[0001] The present invention relates to a polyester heat-shrinkable film that is easy to recycle.

[0002] Among polymers, polyester resins are widely used in various fields due to their superior mechanical strength, heat resistance, transparency, and gas barrier properties. In particular, heat-shrinkable films manufactured using polyester resins exhibit high heat resistance and an appropriate heat shrinkage rate, making them suitable for packaging and / or labeling plastic containers such as PET bottles.

[0003] While plastic containers make our lives more convenient, their indiscriminate disposal and excessive use are causing serious environmental problems. Consequently, various methods are being developed to recycle used plastic containers. The recycling process for these waste plastic containers can be divided into physical recycling, which involves washing and crushing, and chemical recycling, which involves depolymerization.

[0004] However, this recycling process requires preprocessing to separate waste plastic by type, which reduces the efficiency of the recycling process. For example, recycling a PET bottle with a polyester film attached as a label requires separating and removing the polyester film from the PET bottle. Containers containing film are either separated from the film at a recycling facility and recycled alone. If the film is not separated, the container is either landfilled or disposed of together. This not only causes environmental pollution but also significantly reduces resource efficiency.

[0005] Recycling plastic containers, in particular, requires the removal of packaging and / or labels incorporated into the containers for aesthetic purposes. Specifically, plastic containers often incorporate heat-shrinkable polyester films as packaging and / or labels. Due to the difference in crystallinity between polyester films and plastic containers, recycling waste plastic containers requires separating (removing) the polyester films from the containers, which reduces their recyclability.

[0006] Meanwhile, the thermal properties of polyester heat-shrinkable films vary significantly depending on the resin, additives, extrusion, and stretching processing conditions. Specifically, the film must be heat-shrinked to fit a container, and then undergo drying and crystallization before it can be recycled along with the container. Different recycling companies apply different heat treatments (temperature, time, etc.), which further alters the film's thermal properties.

[0007] The Association of Plastic Recyclers (APR)'s clumping test is a method for assessing the recyclability of existing heat-shrinkable films. This test involves mixing PET flakes with 3% film in a hot-air oven at 210°C (changed to 195°C) for 90 minutes to assess fusion. Samples that are not fused or have a weak fusion are then sieved, and the content of the material remaining on the sieve is measured for evaluation.

[0008] However, the aforementioned clumping test lacks clear guidelines regarding sieving speed, height, etc., resulting in varying results (the amount of residue remaining on the sieve) depending on the individual. This difference is particularly significant for samples with weak fusion. Furthermore, as evidenced by the change in APR regulations, the clumping test conditions are laboratory conditions. Because actual recyclers vary in heat treatment temperature and time, it's difficult to directly apply the aforementioned conditions.

[0009] [Prior Art Literature]

[0010] [Patent Document]

[0011] (Patent Document 1) Republic of Korea Patent Publication No. 2009-0062882

[0012] In this way, it is impossible to predict deformation such as melting or sticking of the film during heat treatment during the recycling process based solely on the thermal properties of the polyester film, and the APR clumping test uses an ambiguous method called sieving, which makes it difficult for those skilled in the art to quantify the strength and degree of fusion, and has the disadvantage that evaluation is only possible under specified temperature (195°C) and time (90 minutes) conditions.

[0013] To address this issue, the inventors conducted research and discovered that by mixing film flakes with PET flakes at various heat treatment temperatures and times, and then analyzing the degree of separation of the fused samples through centrifugation after heat treatment, recyclability under these conditions can be quantified. Furthermore, the inventors confirmed that film recyclability is facilitated under these conditions when the difference between the melting temperature measured after the heat treatment and the heat treatment temperature is within a specific range.

[0014] Accordingly, the present invention provides a polyester film that can be recycled together with PET containers without the need for separation, thereby reducing environmental pollution and enhancing resource utilization efficiency. Specifically, the present invention aims to provide a polyester heat-shrinkable film whose recyclability can be controlled within a specific range through quantitative criteria and which facilitates recycling under various conditions.

[0015] In accordance with the above task, the present invention provides a heat-shrinkable film comprising a copolymerized polyester resin comprising a diol component and a dicarboxylic acid component, wherein a mixture of flakes obtained by cutting the film into squares with a side length of 10 mm or less and flakes obtained by crushing a polyethylene terephthalate (PET) container to have a particle diameter of 12.5 mm or less in a weight ratio of 3:97 is obtained, and after heat treatment at 140°C to 210°C for 30 minutes to 90 minutes, no fused material is generated or the slope of a linear regression curve of the following separation rate (%) according to G-force (G) upon centrifugation of the generated fused material is 0.02% / G or more.

[0016] Separation rate (%) = [Total weight of flakes separated from the fused material during centrifugation (g) / Weight of initial fused material (g)] x 100.

[0017] In addition, the present invention provides a film comprising a copolymerized polyester resin including a diol component and a dicarboxylic acid component, wherein a mixture of flakes cut into squares with a side length of 10 mm or less and flakes crushed into a polyethylene terephthalate (PET) container with a particle diameter of 12.5 mm or less is obtained in a weight ratio of 3:97, and the mixture of flakes is heat-treated at 140°C to 210°C for 30 to 90 minutes, and then the temperature is increased from 20°C to 280°C at a rate of 10°C / min through a differential scanning calorimeter (DSC), and at the first scan, the melting temperature (T) is measured at a temperature 10°C lower than the heat treatment temperature or higher. m ) is provided.

[0018] The heat-shrinkable film according to the present invention is mixed with PET flakes, heat-treated, and then centrifuged, and the slope of the linear regression curve of the separation rate according to G-force is controlled within a certain range, so that the recyclability under various conditions can be quantitatively controlled compared to a heat-shrinkable film that has passed a conventional clumping test.

[0019] In addition, the heat-shrinkable film according to the present invention can be recycled very easily under various conditions compared to a heat-shrinkable film that has passed a conventional clumping test, since the difference between the melting temperature measured after mixing with PET flakes and heat treatment and the heat treatment temperature is controlled within a specific range.

[0020] Figures 1 to 7 show graphs and linear regression curves of the separation rate according to G-force when centrifuging a mixture of heat-shrinkable film flakes and PET flakes after heat treatment in Test Example 2.

[0021] The terms used to refer to each component in this specification are used to distinguish it from other components and are not intended to limit the implementation examples. Furthermore, the singular expressions used in this specification include the plural expressions unless the context clearly dictates otherwise.

[0022] In this specification, the terms "first," "second," etc. are used to describe various components, and the components should not be limited by the terms. The terms are used for the purpose of distinguishing one component from another.

[0023] The word "comprising" or "including" in this specification is intended to specify particular features, regions, steps, processes, elements and / or components, and does not exclude the presence or addition of other features, regions, steps, processes, elements and / or components, unless specifically stated to the contrary.

[0024] The molecular weight of the compound described in this specification or the molecular weight of the polymer, for example, the number average molecular weight or the weight average molecular weight, is a relative mass based on carbon-12, as is well known, and does not specify a unit, but may be understood as a molar mass (g / mol) of the same numerical value, if necessary.

[0025] In the numerical ranges that limit the size, physical properties, etc. of the components described in this specification, if a numerical range limited only to the upper limit and a numerical range limited only to the lower limit are separately exemplified, it should be understood that a numerical range in which these upper and lower limits are combined is also included in the exemplary range of the present invention.

[0026]

[0027] Fusion properties of heat-shrinkable films

[0028]

[0029] A heat-shrinkable film according to one embodiment of the present invention is obtained by obtaining a mixture of flakes cut into squares with a side length of 10 mm or less from the film and flakes crushed into a particle size of 12.5 mm or less from a polyethylene terephthalate (PET) container in a weight ratio of 3:97, and heat-treating the mixture at 140°C to 210°C for 30 to 90 minutes, after which no fused material is generated or the slope of a linear regression curve of the following separation rate (%) according to G-force (G) upon centrifugation of the generated fused material is 0.02% / G or more.

[0030] Separation rate (%) = [Total weight of flakes separated from the fused material during centrifugation (g) / Weight of initial fused material (g)] x 100.

[0031] In this way, the fusion characteristics of the heat-shrinkable film according to one embodiment can be evaluated by obtaining a mixture of a polyester heat-shrinkable film cut into square flakes with a side length of 10 mm or less and a polyethylene terephthalate (PET) container crushed to a particle size of 12.5 mm or less in a weight ratio of 3:97, heat-treating the mixture at 140°C to 210°C for 30 to 90 minutes, checking whether a fusion product is generated after the heat treatment, and if a fusion product is generated, checking whether the slope of the linear regression curve of the separation rate (%) according to the corresponding G-force (G) when the fusion product is centrifuged is 0.02% / G or more.

[0032] First, polyester heat-shrinkable film is cut into square flakes (film flakes) with sides of 10 mm or less. Furthermore, flakes (PET flakes) obtained by crushing polyethylene terephthalate (PET) containers to a particle size of 12.5 mm or less are obtained. For example, PET containers can be crushed in a crusher and passed through a sieve with a mesh size of 12.5 mm to obtain flakes. Thereafter, a mixture of these flakes (film flakes and PET flakes) is obtained.

[0033] The above flake mixture is subjected to heat treatment. The heat treatment of the flake mixture can be performed using, for example, a convection oven, a hot air tunnel, etc.

[0034] The heat treatment temperature of the flake mixture may be, for example, 140°C or higher, 150°C or higher, 160°C or higher, or 170°C or higher, and may also be 210°C or lower, 200°C or lower, 190°C or lower, or 180°C or lower. In one embodiment, the heat treatment temperature of the flake mixture is 140°C to 210°C. More specifically, the heat treatment temperature of the flake mixture may be 150°C to 200°C.

[0035] The heat treatment time of the flake mixture may be, for example, 30 minutes or more, 40 minutes or more, 50 minutes or more, or 60 minutes or more, and may also be 90 minutes or less, 80 minutes or less, or 70 minutes or less. In one embodiment, the heat treatment time of the flake mixture is 30 minutes to 90 minutes.

[0036] Check whether there is any fusion material formed after the above heat treatment. After the above heat treatment, the film flakes can maintain their shape without completely melting.

[0037] According to one embodiment, after the heat treatment, the film flakes may not be fused with the PET flakes.

[0038] According to another embodiment, after the heat treatment, the film flakes may form some fusion bonds with the PET flakes. The presence or absence of such fusion bonds between the film flakes and the PET flakes can be determined by visual observation.

[0039] The size of the above-mentioned fusion product may be below a certain level. For example, the size of the fusion product of the film flakes and PET flakes formed after the heat treatment may not exceed twice the size of the PET flakes. As another example, the size of the fusion product of the film flakes and PET flakes formed after the heat treatment may not exceed 1.5 times the size of the PET flakes.

[0040] In this way, after heat treatment of the flake mixture, no fusion products may be generated, or fusion products having a particle size less than twice the particle size of the flakes of the PET container may be generated.

[0041] The fused material formed after the above heat treatment is subjected to centrifugation. For example, the centrifugation can be performed at a G-force range of 100 G to 650 G.

[0042] Specifically, a certain amount (e.g., 3 g) of the above-mentioned fusion material is taken, filled in a conical tube to 25% or less, mounted on a centrifuge, and then allowed to reach a set G-force value and maintained for 1 minute. After centrifugation, the flakes separated from the fusion material are collected and weighed. Whether or not the flakes are separated from the fusion material in this way can be determined by visual observation. Thereafter, the separation rate (%) is calculated according to the equation described above. This procedure is performed at various G-forces to obtain the separation rate (%) during centrifugation at each G-force. For example, data can be collected by performing centrifugation 5 or more times at different G-forces within the range of 100 G to 650 G.

[0043] From the data collected in this way, a regression analysis is performed to model a linear correlation, including the intercept, with G-force (G) as the independent variable x and the separation rate (%) as the dependent variable y. The slope of the linear regression curve is obtained through regression analysis.

[0044] According to one embodiment, the slope of the linear regression curve is 0.02% / G or greater. Within this range, it can be determined that the recycling process of a polyester heat-shrinkable film subjected to heat treatment under the above conditions is excellent with PET.

[0045] For example, the slope of the linear regression curve may be 0.02% / G or more, 0.025% / G or more, 0.03% / G or more, or 0.035% / G or more.

[0046] Meanwhile, the upper limit of the slope of the linear regression curve is not particularly limited, but may be, for example, 1 or less, 0.9 or less, 0.7 or less, 0.5 or less, 0.3 or less, 0.1 or less, or 0.07 or less or 0.05 or less.

[0047] As a specific example, the slope of the linear regression curve may be 0.02% / G to 1% / G or less, 0.02% / G to 0.3% / G or less, 0.02% / G to 0.1% / G or less, or 0.02% / G to 0.05% / G or less.

[0048]

[0049] Thermal properties of heat-shrinkable films

[0050] Polyethylene terephthalate (PET), which is composed only of terephthalic acid (TPA) and ethylene glycol (EG), has a high crystallinity due to a regular molecular arrangement. However, when it is stretched, the additional increase in crystallinity due to stretching orientation suppresses the shrinkage phenomenon due to heat, making it difficult to apply it to heat-shrinkable films that require high shrinkage. Therefore, other co-monomers such as cyclohexanedimethanol (CHDM), neopentyl glycol (NPG), diethylene glycol (DEG), and 1,4-butanediol (1,4-BD) are introduced for heat-shrinkable films. As the content of these co-monomers increases, the crystallinity decreases and the amorphous ratio increases, which can enable high shrinkage. In general, as the content of the co-monomer increases, the melting temperature (T) m ) is lowered and the melting temperature (T m ) also decreases, confirming that the crystallinity decreases. In addition, resins having a certain content of comonomers have a melting temperature (T ) higher than that of comonomers when measured by DSC. m ) can be transformed into an indeterminacy that cannot be confirmed.

[0051] However, polymers cannot be 100% crystalline or 100% amorphous, and the ratio of these can be seen to change depending on the content of the comonomer while they are mixed. In particular, in resins, the melting temperature (T m ) may appear in a small amount of crystalline region depending on the stretching direction when stretching an amorphous resin that does not show a melting point (T). Accordingly, the resin has a melting temperature (T m) does not appear in the stretched film, the melting temperature (T m ) may appear.

[0052] Heat-shrinkable films for high shrinkage are made of resin compositions with a high amorphous region, so the resin has a melting temperature (T m ) does not appear or appears very small, the melting temperature (T) in the stretched film is determined by the stretching orientation. m ) is observed. Therefore, the melting temperature (T) of the resin or stretched film determines how much temperature and time the actual film can remain unmelted. m ) alone cannot be known. This is because, at some temperatures, the crystals may grow larger and Tm and △H may increase, but at other temperatures, even the already formed crystals may melt.

[0053] Therefore, the melting temperature (T) of a typical film m ) alone cannot tell whether a recycling process is possible with heat treatment under specific conditions, and the melting temperature (T) of the film after heat treatment under those conditions m ) is important. After heat treatment of the mixture of film flakes and PET flakes, the melting temperature (T m ) can be checked and judged. The specific method and conditions for manufacturing and heat treatment of the above flake mixture can be applied as exemplified in the explanation of the recyclability of the heat-shrinkable film above.

[0054] To measure the melting temperature of a film, a differential scanning calorimeter (DSC) can be used, specifically a modulated DSC (MDSC), more specifically a temperature-modulated DSC (TMDSC). The melting temperature of the film can be measured, for example, by scanning the differential scanning calorimeter (DSC) while heating from room temperature (e.g., 20°C) to 280°C at a rate of 10°C / min.

[0055] A heat-shrinkable film according to one embodiment is obtained by obtaining a mixture of flakes cut into squares with a side length of 10 mm or less and flakes crushed into a polyethylene terephthalate (PET) container with a particle diameter of 12.5 mm or less in a weight ratio of 3:97, heat-treating the mixture of flakes at 140°C to 210°C for 30 to 90 minutes, and then increasing the temperature from 20°C to 280°C at a rate of 10°C / min through a differential scanning calorimeter (DSC) and, at the first scan, measuring the melting temperature (T) at a temperature 10°C lower than the heat-treatment temperature or higher. m ) can be expressed.

[0056] That is, the value obtained by subtracting the melting temperature (℃) from the heat treatment temperature (℃) of the film may be 10℃ or less. Within the above preferred range, it can be determined that the recycling process of the polyester heat-shrinkable film and PET that undergo heat treatment under the above conditions is excellent.

[0057] Accordingly, a step of obtaining a mixture of a polyester heat-shrinkable film cut into square flakes with one side (10 mm or less) and a polyethylene terephthalate (PET) container crushed into flakes with a particle size of (10 mm or less) in a weight ratio of 3:97, heat-treating the mixture at 140°C to 210°C for 30 to 90 minutes; and using a differential scanning calorimeter (DSC) to increase the temperature of the heat-treated flake mixture at a rate of 10°C / min from 20°C to 280°C, and checking whether the mixture exhibits a melting temperature at a temperature 10°C lower than the heat-treatment temperature or higher (i.e., a temperature higher than the heat-treatment temperature minus 10°C) during the first scan, thereby evaluating the recyclability of the heat-shrinkable film.

[0058] In addition, the melting temperature (T) is at a temperature 5℃ lower than the above heat treatment temperature. m ) can be expressed. That is, the value obtained by subtracting the melting temperature (℃) from the heat treatment temperature (℃) of the film may be 5℃ or less.

[0059] More specifically, the melting temperature (T) is at a temperature higher than the heat treatment temperature. m ) can be expressed. That is, the value obtained by subtracting the melting temperature (℃) from the heat treatment temperature (℃) of the film can be 0℃ or less.

[0060] Melting temperature (T) shown in the first DSC scan after heat treatment of the heat-shrinkable film m ) can be one or more, and if there are two or more, the higher temperature is the melting temperature (T m ) can be considered.

[0061] In addition, the melting temperature (T) was measured during the first DSC scan after the above heat treatment. m ) may have a melting enthalpy (△H) above a certain level. For example, the melting temperature (T) in the first scan m ) may have △H of 0.1 J / g or more. Specifically, the melting temperature (T) at the first scan m ) may be 0.5 J / g or more, 1 J / g or more, 2 J / g or more, 3 J / g or more, 5 J / g or more, 7 J / g or more, or 10 J / g or more. More specifically, the melting temperature (T m ) in which △H may be 0.1 J / g to 100 J / g, 0.1 J / g to 50 J / g, 0.1 J / g to 30 J / g, 0.5 J / g to 100 J / g, 0.5 J / g to 50 J / g, 0.5 J / g to 30 J / g, or 0.5 J / g to 20 J / g. The presence of a melting temperature (Tm) and a melting enthalpy (△H) even after heat treatment within the above preferred ranges means that the film flakes are not completely melted at the heat treatment temperature and time and are not fused with the PET flakes, or are easily separated even if fused, and this can be quantitatively confirmed in this way.

[0062] However, after heat treatment of the above flake mixture and the first DSC scan, the melting temperature (T) was measured in the second scan. m ) may not appear. Since all thermal history during film manufacturing is removed after the first scan, the melting temperature obtained from the second scan can be regarded as the melting temperature of the copolymerized polyester resin that is the raw material for the film.

[0063] Specifically, after the first scan, the temperature was increased from 20°C to 280°C at a rate of 10°C / min using a differential scanning calorimeter (DSC), and the melting temperature (T) was measured during the second scan. m ) may not appear. In this way, if the melting temperature does not appear during the second scan, there is an advantage in that the film has low crystallinity and thus a high shrinkage rate can be obtained.

[0064] The heat-shrinkable film according to the present invention has excellent shrinkage characteristics at the temperature applied to the heat-shrinkage process.

[0065] The heat-shrinkable film may have a shrinkage ratio in the main shrinkage direction of 40% or more under the conditions of 85°C and 15 seconds. For example, the heat-shrinkable film may have a shrinkage ratio in the main shrinkage direction of 42% or more, 44% or more, 46% or more, 48% or more, 50% or more, 52% or more, 55% or more, or 60% or more under the conditions of 85°C and 15 seconds. Specifically, the heat-shrinkable film may have a shrinkage ratio in the main shrinkage direction of 40% to 80%, or 40% to 75%.

[0066] In addition, the heat-shrinkable film may have a shrinkage ratio in the main shrinkage direction of 50% or more under the conditions of 95°C and 15 seconds. For example, the heat-shrinkable film may have a shrinkage ratio in the main shrinkage direction of 51% or more, 52% or more, 54% or more, 56% or more, 60% or more, 63% or more, 65% or more, or 70% or more under the conditions of 95°C and 15 seconds. As a specific example, the heat-shrinkable film may have a shrinkage ratio in the main shrinkage direction of 60% or more under the conditions of 95°C and 15 seconds. Specifically, the heat-shrinkable film may have a shrinkage ratio in the main shrinkage direction of 50% to 80%, or 60% to 80%.

[0067] Accordingly, the heat-shrinkable film of the present invention can be used as a label, cap seal, or packaging material for various containers such as plastic.

[0068]

[0069] Components of heat-shrinkable film

[0070] A heat-shrinkable film according to the present invention comprises a copolymerized polyester resin containing a diol component and a dicarboxylic acid component.

[0071] According to the present invention, the diol component may be a commonly known diol component.

[0072] Specifically, the diol component is bis(2-hydroxyethyl)terephthalate (BHET), isosorbide, neopentyl glycol, ethylene glycol, cyclohexanedimethanol, 1,2-propanediol, 1,3-propanediol, 2-methyl-1,3-propanediol, 2-methylene-1,3-propanediol, 2-ethyl-1,3-propanediol, 2-isopropyl-1,3-propanediol, 2,2-dimethyl-1,3-propanediol, 1,4-butanediol, 2,3-butanediol, 3-methyl-1,5-pentanediol, 3-methyl-2,4-pentanediol, 1,6-hexanediol, 1,2-cyclohexanediol, 1,4-cyclohexanediol, diethylene glycol, It may be at least one selected from the group consisting of 4-(hydroxymethyl)cyclohexylmethyl 4-(hydroxymethyl)cyclohexanecarboxylate, and 4-(4-(hydroxymethyl)cyclohexylmethoxymethyl)cyclohexylmethanol.

[0073] Preferably, when considering the crystallinity, heat shrinkability, economic efficiency, etc. of the polyester heat-shrinkable film, the diol component may include two or more (specifically, three or more, four or more, or five or more) selected from the group consisting of bis(2-hydroxyethyl)terephthalate, isosorbide, ethylene glycol, cyclohexanedimethanol, neopentyl glycol, diethylene glycol, 4-(hydroxymethyl)cyclohexylmethyl 4-(hydroxymethyl)cyclohexanecarboxylate, and 4-(4-(hydroxymethyl)cyclohexylmethoxymethyl)cyclohexylmethanol.

[0074] For example, the diol component may include ethylene glycol and, as a comonomer, at least one (specifically, at least two, at least three, or at least four) selected from the group consisting of bis(2-hydroxyethyl)terephthalate, isosorbide, cyclohexanedimethanol, neopentylglycol, diethylene glycol, 4-(hydroxymethyl)cyclohexylmethyl 4-(hydroxymethyl)cyclohexanecarboxylate, and 4-(4-(hydroxymethyl)cyclohexylmethoxymethyl)cyclohexylmethanol.

[0075] When the above diol component includes ethylene glycol and a comonomer, the amounts of these components used are not particularly limited, but based on the total weight of the diol component, the amount of ethylene glycol used may be 10 to less than 100 wt%, 15 to 90 wt%, 20 to 85 wt%, 30 to 85 wt%, or 50 to 85 wt%, and the amount of the comonomer used may be more than 0 to 90 wt%, more than 0 to 85 wt%, 1 to 90 wt%, 1 to 50 wt%, 2 to 50 wt%, 10 to 85 wt%, 15 to 80 wt%, 15 to 70 wt%, or 15 to 50 wt%.

[0076] In particular, when diethylene glycol is used as the comonomer, the amount of diethylene glycol used may be 0 to 50 wt%, 1 to 50 wt%, 1 to 45 wt%, 1 to 40 wt%, 2 to 50 wt%, 3 to 45 wt%, 4 to 40 wt%, or 5 to 35 wt%, based on the total weight of the diol component.

[0077] Accordingly, the polyester resin according to the present invention may contain a structural unit derived from the diethylene glycol in an amount of 0 to 50 wt%, 1 to 50 wt%, 2 to 50 wt%, 3 to 45 wt%, 4 to 40 wt%, or 5 to 35 wt%, based on the total weight of the polyester resin.

[0078] According to the present invention, the dicarboxylic acid component may be a commonly known dicarboxylic acid component.

[0079] Specifically, the dicarboxylic acid component may include at least one selected from the group consisting of isophthalic acid, terephthalic acid, dimethyl isophthalate, phthalic acid, dimethyl phthalate, phthalic anhydride, 2,6-naphthalenedicarboxylic acid, dimethyl 2,6-naphthalenedicarboxylate, diphenyl dicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, dimethyl 1,4-cyclohexanedicarboxylate, dimethyl 1,3-cyclohexanedicarboxylate, sebacic acid, succinic acid, isodecylsuccinic acid, maleic acid, maleic anhydride, fumaric acid, adipic acid, glutaric acid, and azelaic acid.

[0080] Preferably, when considering the crystallinity and heat shrinkage properties of the polyester stretch film, the dicarboxylic acid component may include at least one selected from the group consisting of isophthalic acid, terephthalic acid, dimethyl phthalate, and dimethyl isophthalate.

[0081] The above diol and dicarboxylic acid may include one or more regenerative monomers.

[0082] As an example, the diol component may include a regenerated monomer obtained by depolymerization of waste polyester. As a specific example, the diol component may include one or more regenerated monomers selected from the group consisting of regenerated diols and regenerated diol derivatives. As a more specific example, the diol component may include one or more regenerated monomers selected from the group consisting of, but not limited to, regenerated bis(2-hydroxyethyl)terephthalate, regenerated ethylene glycol, regenerated 1,4-cyclohexanedimethanol, regenerated neopentyl glycol, regenerated diethylene glycol, and regenerated isosorbide.

[0083] As another example, the dicarboxylic acid component may include a regenerated monomer obtained by depolymerization of waste polyester. As a specific example, the dicarboxylic acid component may include one or more regenerated monomers selected from the group consisting of regenerated dicarboxylic acids and regenerated dicarboxylic acid derivatives. As a more specific example, the dicarboxylic acid component may include one or more regenerated monomers selected from the group consisting of, but not limited to, regenerated isophthalic acid, regenerated terephthalic acid, regenerated dimethyl isophthalate, and regenerated dimethyl phthalate.

[0084] The regenerated monomer obtained by depolymerizing waste polyester must be understood distinctly from virgin monomer or pure monomer compounds. Specifically, the regenerated monomer contains reagents or solvents used in the various chemical steps during depolymerization from waste polyester, or by-products generated by side reactions with these reagents or solvents. Therefore, the regenerated monomer obtained through typical depolymerization methods often contains organic and inorganic impurities in addition to the main monomer compound, resulting in a low purity. For this reason, the regenerated monomer can be viewed as a composition comprising two or more components.

[0085] According to the present invention, the polyester resin may have an intrinsic viscosity (IV) at 35°C of 0.5 to 1.2 dl / g, 0.4 to 1.2 dl / g, and specifically, 0.52 to 1.15 dl / g, 0.55 to 1.13 dl / g, 0.58 to 1.1 dl / g, 0.6 to 0.9 dl / g, 0.62 to 0.88 dl / g, 0.65 to 0.85 dl / g, 0.68 to 0.83 dl / g, or 0.7 to 0.8 dl / g. As the intrinsic viscosity is within the above range, the processability of the polyester resin can be secured.

[0086]

[0087] Method for manufacturing heat-shrinkable film

[0088] A method for manufacturing a heat-shrinkable film according to the present invention may include a step (S-1) of manufacturing a polyester resin by polymerizing a diol component and a dicarboxylic acid component; and a step (S-2) of manufacturing a stretched film from the polyester resin.

[0089] The above step (S-1) is a step for producing a polyester resin (copolymer) by polymerizing a diol component and a dicarboxylic acid component. Descriptions of each of the diol component and the dicarboxylic acid component for the polymerization are the same as those described above, and therefore are omitted.

[0090] The polymerization of the above diol component and the above dicarboxylic acid component can be carried out by a conventionally known method (e.g., liquid phase polymerization, solid phase polymerization, etc.), and a batch reactor or a continuous reactor can be used for the polymerization reaction. Specifically, the polymerization reaction can include an esterification reaction (esterification exchange reaction) in which the diol component and the dicarboxylic acid component are reacted to produce an oligomer, and a polycondensation reaction of the oligomer.

[0091] The temperature at which the esterification reaction takes place is not particularly limited, but considering the properties of the polyester resin and the polyester stretched film, it may be 230°C to 270°C, 235°C to 268°C, 240°C to 265°C, or 240°C to 260°C. In addition, the time at which the esterification reaction takes place is not particularly limited, but may be 1 to 24 hours, 2 to 22 hours, 3 to 20 hours, or 4 to 18 hours. In addition, the pressure at which the esterification reaction takes place is not particularly limited, but may be 0 to 5.0 kgf / cm. 2 , 0.1 to 4.5 kgf / cm 2 , 0.1 to 4.0 kgf / cm 2 , or 0.1 to 3.0 kgf / cm 2It could be.

[0092] The temperature at which the polycondensation reaction takes place is not particularly limited, but considering the properties of the polyester resin and the polyester stretched film, it may be 245°C to 290°C, 250°C to 285°C, 255°C to 280°C, or 255°C to 270°C. In addition, the time at which the polycondensation reaction takes place is not particularly limited, but may be 1 to 24 hours, 2 to 24 hours, 5 to 22 hours, or 7 to 20 hours.

[0093] Meanwhile, an additive including at least one selected from the group consisting of a catalyst, a stabilizer, a coloring agent, a crystallizer, an antioxidant, and a branching agent may be added to the polymerization reaction.

[0094] For example, the copolymerized polyester resin may include at least one selected from the group consisting of antimony (Sb), titanium (Ti), zinc (Zn), germanium (Ge), magnesium (Mg), and manganese (Mn) as a polymerization catalyst. As a specific example, the catalyst may be tetraethyl titanate, acetyltripropyl titanate, tetrapropyl titanate, tetrabutyl titanate, 2-ethylhexyl titanate, octylene glycol titanate, triethanolamine titanate, acetylacetonate titanate, ethylacetoacetic ester titanate, isostearyl titanate, titanium dioxide, germanium dioxide, germanium tetrachloride, germanium ethyleneglycoxide, germanium acetate, or a combination thereof.

[0095] The above stabilizer is not particularly limited, but phosphorus compounds such as phosphoric acid, trimethyl phosphate, and triethyl phosphate can be used.

[0096] The above coloring agent is not particularly limited, but organic compounds such as cobalt compounds, anthraquionone compounds, perinone compounds, azo compounds, and methine compounds (e.g., cobalt acetate, cobalt propionate, blue toner, red toner) can be used.

[0097] The above crystallizer is not particularly limited, but a crystal nucleating agent, an ultraviolet absorber, a polyolefin resin, a polyamide resin, etc. can be used.

[0098] The above antioxidant is not particularly limited, but hindered phenol compounds, phosphite compounds, thioether compounds, etc. can be used.

[0099] The above branching agent is not particularly limited, but trimellitic anhydride, trimellitic propane, trimellitic acid, etc. can be used.

[0100] The above step (S-2) is a step for producing a stretched film from the polyester resin obtained in the above step (S-1). The production of the stretched film can be carried out by a conventionally known method, and for example, a film including the copolymerized polyester resin can be produced by including a step of molding a polyester resin mixture to produce an unstretched sheet; and a step of stretching the unstretched sheet. Specifically, the stretched film can be produced through a process of melting and casting a polyester resin, a uniaxial or biaxial stretching process, or the like.

[0101] The melting and molding process of the polyester resin may be performed through an extruder, and at this time, the melt extrusion temperature may be, for example, 180°C or higher, 200°C or higher, 230°C or higher, 250°C or higher, 255°C or higher, or 260°C or higher, and may also be 310°C or lower, 300°C or lower, 290°C or lower, or 280°C or lower, and specifically, may be 180°C to 310°C, 200°C to 310°C, 230°C to 310°C, or 240°C to 300°C. Preferably, the melt extrusion temperature may be 255°C or higher, and for example, may be 255°C to 310°C, 255°C to 300°C, or 255°C to 290°C. When the melt extrusion temperature is within the above-described preferred range, the molecular weight and crystallinity of the polyester resin are improved, so that the heat-shrinkable film manufactured therefrom is easy to recycle under various conditions and the recyclability is also advantageous in quantitatively controlling it.

[0102] In addition, the molding temperature may be, for example, 15°C to 60°C, or 15°C to 45°C. By performing this process, an unstretched sheet can be obtained, and the obtained unstretched sheet can be passed on to a stretching process. The unstretched sheet can be preheated to a predetermined temperature (for example, 80°C to 120°C) before undergoing the stretching process.

[0103] The above-described uniaxial or biaxial stretching process may include stretching the unstretched sheet obtained through the above-described melting and molding process in the machine direction (MD), the transverse direction (TD), or both. The stretching in the machine direction may be performed at a stretching ratio of 1 to 6 times, 1 to 5.5 times, 1 to 5 times, 1.05 to 6 times, 1.1 to 6 times, 1.1 to 5.5 times, 1.1 to 5 times, 1.1 to 4.5 times, or 1.2 to 5.5 times at a temperature of 55°C to 180°C, 60°C to 130°C, 60°C to 120°C, or 65°C to 90°C. In addition, the stretching temperature in the transverse direction may be 55°C to 180°C, 60°C to 130°C, or 65°C to 90°C, and the stretching ratio may be 1.1 times or more, 1.5 times or more, 2.5 times or more, 3.5 times or more, or 4 times or more, and may also be 6 times or less, 5.5 times or less, or 5 times or less, and specifically, may be 1.5 to 6 times, or 2.5 to 5.5 times.

[0104] In one specific example, the film comprising the copolymerized polyester resin may be uniaxially stretched with a transverse stretch ratio of 1.5 to 6 times or a longitudinal stretch ratio of 1.05 to 6 times. In another specific example, the film comprising the copolymerized polyester resin may be biaxially stretched with a transverse stretch ratio of 1.5 to 6 times and a longitudinal stretch ratio of 1.05 to 6 times.

[0105] The above-mentioned stretched film may additionally undergo a heat-setting step. The temperature at which the above-mentioned stretched film is heat-set is not particularly limited, but may be similar to or higher than the stretching process temperature. Specifically, the heat-setting temperature may be 60°C to 200°C, 65°C to 190°C, 65°C to 180°C, or 65°C to 170°C. When the heat-setting temperature is within the above range, a polyester stretched film with enhanced crystallinity and mechanical strength can be produced.

[0106] The thickness of the heat-shrinkable film manufactured in this way may be, for example, 10 µm or more, 15 µm or more, 25 µm or more, 35 µm or more, or 50 µm or more, and may also be 500 µm or less, 300 µm or less, 200 µm or less, or 100 µm or less. As a specific example, the thickness of the heat-shrinkable film may be 10 µm to 100 µm.

[0107] The film comprising the above copolymerized polyester resin may be composed of one or more layers. For example, the film comprising the above copolymerized polyester resin may be a single-layer film. As another example, the film comprising the above copolymerized polyester resin may be a single-layer film composed of two or more layers. As a specific example, the film comprising the above copolymerized polyester resin may be a multilayer film comprising a substrate layer and a resin layer. In this case, at least one layer of the substrate layer and the resin layer may comprise a copolymerized polyester resin.

[0108] [Example]

[0109] Hereinafter, preferred examples are presented to aid understanding of the present invention. However, the following examples are provided solely to facilitate understanding of the present invention and are not intended to limit the scope of the present invention.

[0110]

[0111] <Manufacture of Copolymerized Polyester Resin>

[0112]

[0113] Manufacturing example: Resin 1

[0114] Into a reactor connected to a column and a condenser capable of being cooled by water, 2950 g of terephthalic acid (TPA), 410 g of ethylene glycol (EG), 970 g of diethylene glycol (DEG), 1180 g of 1,4-cyclohexanedimethanol (CHDM), and 1130 g of bis(2-hydroxyethyl) terephthalate (BHET) obtained by depolymerization of recycled PET were charged, and 20 ppm of a Ti catalyst and 70 ppm of a phosphorus stabilizer based on the weight of the monomer mixture were charged. Next, the temperature of the reactor was raised to 260°C, and an esterification reaction (ES) was performed under a pressure of 2 kgf / cm2 to obtain a transparent reactant.

[0115] Next, the reactants were transferred to a polycondensation reactor, and a polycondensation reaction (PA) was performed at 265°C while maintaining the pressure of the polycondensation reactor lower than atmospheric pressure. When the intrinsic viscosity (IV) of the reactants inside the polycondensation reactor reached 0.65 to 0.75 dl / g, the reactants were discharged outside the polycondensation reactor to form strands, which were then solidified with a cooling liquid and granulated to an average weight of approximately 15 mg, thereby manufacturing polyester resin (copolymer) chips.

[0116]

[0117] Manufacturing example: Resin 2

[0118] 3861 g of terephthalic acid (TPA), 1605 g of ethylene glycol (EG), 435 g of diethylene glycol (DEG), and 705 g of recycled 1,4-cyclohexanedimethanol (CHDM) were charged into a reactor connected to a column and a condenser capable of being cooled by water, and a polyester resin (copolymer) chip was manufactured in the same manner as the above resin 1.

[0119]

[0120] Manufacturing example: Resin 3

[0121] 3952 g of terephthalic acid (TPA), 1755 g of recycled ethylene glycol (EG), 386 g of diethylene glycol (DEG), and 541 g of 1,4-cyclohexanedimethanol (CHDM) were charged into a reactor connected to a column and a condenser capable of being cooled by water, and a polyester resin (copolymer) chip was manufactured in the same manner as the resin 1.

[0122]

[0123] Manufacturing example: Resin 4

[0124] 4131 g of recycled terephthalic acid (TPA), 2224 g of ethylene glycol (EG), 155 g of diethylene glycol (DEG), and 518 g of neopentyl glycol (NPG) were charged into a reactor connected to a column and a condenser capable of being cooled by water, and a polyester resin (copolymer) chip was manufactured in the same manner as the above resin 1.

[0125]

[0126] Manufacturing example: Resin 5

[0127] 4044 g of terephthalic acid (TPA), 1672 g of ethylene glycol (EG), 46 g of diethylene glycol (DEG), and 950 g of neopentyl glycol (NPG) were charged into a reactor connected to a column and a condenser capable of being cooled by water, and a polyester resin (copolymer) chip was manufactured in the same manner as the above resin 1.

[0128]

[0129] Manufacturing example: Resin 6

[0130] 4055 g of terephthalic acid (TPA), 1709 g of ethylene glycol (EG), 152 g of diethylene glycol (DEG), and 794 g of neopentyl glycol (NPG) were charged into a reactor connected to a column and a condenser capable of being cooled by water, and a polyester resin (copolymer) chip was manufactured in the same manner as the resin 1.

[0131]

[0132] <Manufacturing of heat-shrinkable film>

[0133]

[0134] Example 1

[0135] Each of the polyester resin chips (Resins 1 to 6) obtained in the above manufacturing examples was fed into an extruder (Collin's Teach-Line) and melt-extruded at a temperature of 255°C and molded at a temperature of 35°C to produce an unstretched polyester sheet. Subsequently, the unstretched sheet was stretched only in the transverse direction (TD) at a stretch ratio of 4.5 times at 78°C and cooled with air to produce an oriented polyester film having a thickness of 50 μm.

[0136]

[0137] Examples 2 to 9

[0138] Each heat-shrinkable film was manufactured in the same manner as in Example 1, but the type of polyester resin chip and the process conditions were changed as shown in Table 1 below.

[0139]

[0140] Comparative Examples 1 to 6

[0141] Each heat-shrinkable film was manufactured in the same manner as in Example 1, but the type of polyester resin chip and the process conditions were changed as shown in Table 2 below.

[0142]

[0143] Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Example 7 Example 8 Example 9 Polyester resin Resin 1 Resin 1 Resin 1 Resin 2 Resin 2 Resin 3 Resin 4 Resin 4 Resin 5 Other--MB-MB-MB--Melt extrusion temperature (℃) 255 260 260 260 260 260 270 260 260 Molding temperature (℃) 35 37 37 30 23 30 35 35 32 TD stretching temperature (℃) 78 88 80 76 74 74 74 7 27 6 TD stretching ratio (times) 4.5 5.5 54.5 54.5 55

[0144] Comparison Example 1 Comparison Example 2 Comparison Example 3 Comparison Example 4 Comparison Example 5 Comparison Example 6 Polyester Resin Resin 2 Resin 3 Resin 4 Resin 5 Resin 5 Resin 6 Other--MB--- Melt Extrusion Temperature (℃) 250 250 250 250 250 250 Molding Temperature (℃) 30 30 33 32 32 40 TD Stretch Temperature (℃) 80 80 78 78 76 9 6 TD Stretch Ratio (times) 554.55 54.7

[0145] <Example of an exam>

[0146]

[0147] Test Example 1: Fusion Evaluation

[0148] (1) Heat treatment

[0149] The heat-shrinkable films manufactured in the above examples and comparative examples were mixed with PET flakes and heat-treated. First, the heat-shrinkable films were cut into squares with sides of 10 mm or less to prepare film flakes. In addition, polyethylene terephthalate (PET) containers were crushed in a crusher and passed through a mesh sieve with a diameter of 12.5 mm to prepare PET flakes in which the polyethylene terephthalate (PET) was crushed. The film flakes and PET flakes were mixed at a weight ratio of 3:97, and then heat-treated under the conditions shown in Tables 3 and 4 below.

[0150] Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Example 7 Example 8 Example 9 Heat treatment temperature (℃) 150 160 170 170 190 200 210 200 160 Heat treatment time (minutes) 60 30 60 30 90 90 90 90 30

[0151] Classification Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 Comparative Example 6 Heat treatment temperature (℃) 200 210 220 180 210 220 Heat treatment time (minutes) 90 90 90 90 90 90

[0152] (2) Fusion evaluation

[0153] After the heat treatment of (1) above, check whether there is any fusion material, and if fusion material has occurred, mark it as “fusion” in Table 5 or 6 below.

[0154] In addition, when fusion occurred, the size (particle size) of the fusion product was measured and the ratio (fusion product size / PET flake size) to the size of the PET flake was indicated in Table 5 or 6 below (i.e., when it was less than twice that of the PET flake, it was indicated as '≤2', and when it was more than twice that of the PET flake, it was indicated as '>2').

[0155] In addition, if the shape of the film is not maintained and melts after the heat treatment of (1) above, it is marked as “melted” in Table 5 or 6 below.

[0156]

[0157] (3) Centrifugation

[0158] In the above (1), 3 g of the fused film flakes and PET flakes by heat treatment was taken, filled into a conical tube to less than 25%, placed in a centrifuge, and then allowed to reach the set G-force value and maintained for 1 minute. As a result, the flakes separated from the fused material during centrifugation were collected, and the total weight was measured. The separation rate (%) was calculated according to the equation below. This procedure was performed at various G-forces within the range of 100 G to 650 G to obtain the separation rate (%).

[0159] Separation rate (%) = [Total weight of flakes separated from the fused material during centrifugation (g) / Weight of initial fused material (g)] x 100

[0160]

[0161] (4) Regression analysis

[0162] Using the separation rate (%) obtained at each G-force, a regression analysis of the separation rate (%) according to G-force was performed, and as a result, the slope and cutoff value of the linear regression curve were obtained.

[0163] Figures 1 to 7 show graphs with G-force as the x-axis and separation rate (%) as the y-axis, the slope of the linear regression curve, and the y-intercept.

[0164]

[0165] Test Example 2: DSC Analysis

[0166]

[0167] (1) Film T before heat treatment m Measurement (DSC) - 1st scan

[0168] Each of the heat-shrinkable films manufactured in the above examples and comparative examples was analyzed using differential scanning calorimetry (DSC) to determine the melting temperature (T m ) was measured. The DSC analysis conditions are as follows.

[0169] DSC analysis device: Mettler Toledo's DSC 1 model was used.

[0170] Sample preparation: Take about 6 to 10 mg of heat-shrinkable film and fill an aluminum pan.

[0171] Scan conditions: DSC curves were obtained by heating from 20°C to 280°C at a rate of 10°C per minute and annealing at 280°C for 3 minutes.

[0172]

[0173] (2) Film T after heat treatment m Measurement (DSC) - 1st scan

[0174] The heat-shrinkable films manufactured in the above examples and comparative examples were cut in the same manner as in (1) of Test Example 1, mixed with PET flakes at a weight ratio of 3:97, and then heat-treated. Thereafter, the melting temperature of the heat-treated film was measured by performing the first scan on a DSC under the same conditions as Test Example 1. Specifically, the endothermic peak temperature that appears at the end of the temperature increase process in the obtained DSC curve (i.e., the highest endothermic peak temperature) was taken as the melting temperature at the first scan (film after heat treatment). When the melting temperature at the first scan after heat treatment was measured, it is shown in Table 5 or 6 below.

[0175]

[0176] (3) Film T mMeasurement (DSC) - Secondary Scan

[0177] In the above Test Example 1, the heat-shrinkable film scanned for the first time was quenched and then scanned again (second scan) using a DSC under the same conditions as the first scan to measure the melting temperature. If the melting temperature was measured during the second scan, it is shown in Table 5 or 6 below. Since all thermal history during film manufacturing is removed after the first scan, the melting temperature obtained from the second scan can also be regarded as the melting temperature of the polyester resin.

[0178]

[0179] Test Example 3: Shrinkage

[0180] Each of the heat-shrinkable films manufactured in the above examples and comparative examples was cut into 5 cm × 5 cm pieces and stored at room temperature (20°C). After immersing the film in warm water at 95°C for 15 seconds, the change in length in the transverse direction (TD), which is the main shrinkage direction, was measured, and the heat shrinkage rate was calculated according to the following equation.

[0181]

[0182] Heat shrinkage (%) = {(F S1 - F S2 ) / F S1} × 100

[0183] (F S1 : TD length of the film before immersion in hot water, F S2 : TD length of the film after immersion in hot water)

[0184]

[0185] The results of the above test are summarized in the table below.

[0186] Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Example 7 Example 8 Example 9 Polyester resin Resin 1 Resin 1 Resin 1 Resin 2 Resin 2 Resin 3 Resin 4 Resin 4 Resin 5 Other--MB-MB-MB--Film T m (2 nd )---------T before heat treatment m (1 st)(℃)156156157165165192191199-95℃ Shrinkage rate (%)787878787877757577Heat treatment temperature (℃)150160170170190200210200160Heat treatment time (min)603060309090909030T after heat treatment m (1 st )(℃)171173175175192195203201167T after heat treatment m △H (1 st )1.10.82.16.43.87.75.328.81.3Whether the film is melted---------Whether it is fused-Fused--Fused---FusedSize of the fused material (x)-≤2--≤2---≤2Weight of the fused material (g)-3--3---3Separation rate (%) at each G-force100G-0--0---0130G-0.7--0---0150G-1--0.3---0200G-2.7--0.7---1.1250G-7--5.3----300G-9.3--7.3---8.4350G---------500G-15--12.7---13.2650G---------Linear regression curve slope (% / G)-0.04--0.035---0.037

[0187] Classification Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 Comparative Example 6 Polyester Resin Resin 2 Resin 3 Resin 4 Resin 5 Resin 5 Resin 6 Other--MB---Film T m (2 nd )------T before heat treatment m (1 st )(℃)165186202--19895℃ Shrinkage rate (%)787775777775Heat treatment temperature (℃)200210220180210220Heat treatment time (min)909090909090T after heat treatment m (1 st )(℃)------T after heat treatment m △H (1 st)------Whether the film is melted or notMelted ...

[0188] As shown in the above table, the heat-shrinkable films of Examples 1 to 9 did not undergo fusion after mixing with PET flakes and heat treatment, or even if fusion occurred, the slope of the linear regression curve of the separation rate according to G-force was within the desired range. In addition, the melting temperature of the heat-shrinkable films of Examples 1 to 9 measured after mixing with PET flakes and heat treatment was within the desired range.

[0189] In contrast, the heat-shrinkable films of Comparative Examples 1 to 6 showed fusion after being mixed with PET flakes and heat-treated, and the slope of the linear regression curve of the separation rate according to G-force also fell outside the desirable range. In addition, the melting temperature of the heat-shrinkable films of Comparative Examples 1 to 6 was not measured after being mixed with PET flakes and heat-treated.

[0190] Therefore, the present invention has the advantage of being able to distinguish recyclable samples by segmenting and quantifying them among fused samples, even if fusion does not occur after heat treatment. Furthermore, as seen in the test results, the polyester heat-shrinkable film according to the present invention is readily recyclable under various heat treatment conditions.

Claims

1. A film comprising a copolymerized polyester resin containing a diol component and a dicarboxylic acid component, A heat-shrinkable film, wherein a mixture of flakes cut into squares with a side length of 10 mm or less and flakes crushed into a polyethylene terephthalate (PET) container with a particle diameter of 12.5 mm or less is obtained in a weight ratio of 3:97, and after heat treatment at 140°C to 210°C for 30 to 90 minutes, no fused material is generated or the slope of the linear regression curve of the following separation rate (%) according to G-force (G) upon centrifugation of the generated fused material is 0.02% / G or more: Separation rate (%) = [Total weight of flakes separated from the fused material during centrifugation (g) / Weight of initial fused material (g)] x 100.

2. In paragraph 1, No fusion products are generated after heat treatment of the above flake mixture, or A heat-shrinkable film in which a fusion product having a particle size less than twice the flake particle size of the PET container is formed.

3. In paragraph 1, The above centrifugation A heat-shrinkable film, which is performed in a G-force range of 100 G to 650 G.

4. In paragraph 1, After heat-treating the above flake mixture at 140°C to 210°C for 30 to 90 minutes, the temperature was increased from 20°C to 280°C at a rate of 10°C / min using a differential scanning calorimeter (DSC), and the melting temperature (T) was measured at a temperature 10°C lower than the heat-treatment temperature or higher during the first scan. m ), a heat-shrinkable film.

5. A film comprising a copolymerized polyester resin containing a diol component and a dicarboxylic acid component, A mixture of flakes cut into squares with a side length of 10 mm or less from the above film and flakes crushed into a particle size of 12.5 mm or less from a polyethylene terephthalate (PET) container is obtained in a weight ratio of 3:97, and the mixture of flakes is heat-treated at 140°C to 210°C for 30 to 90 minutes, and then the temperature is increased from 20°C to 280°C at a rate of 10°C / min through a differential scanning calorimeter (DSC) and, at the first scan, the melting temperature (T) is measured at a temperature 10°C lower than the heat treatment temperature or higher. m ), a heat-shrinkable film.

6. In paragraph 5, The melting temperature (T) at the first scan above m ) A heat-shrinkable film having a △H of 0.1 J / g or more.

7. In paragraph 5, After the first scan above, The temperature was increased from 20°C to 280°C at a rate of 10°C / min using a differential scanning calorimeter (DSC), and the melting temperature (T) was measured during the second scan. m ) does not appear, heat-shrinkable film.

8. In paragraph 1 or paragraph 5, The above heat-shrinkable film A heat-shrinkable film having a shrinkage rate in the main shrinkage direction of 60% or more under conditions of 95°C and 15 seconds.

9. In paragraph 1 or paragraph 5, The above heat-shrinkable film A heat-shrinkable film having a shrinkage rate in the main shrinkage direction of 40% or more under conditions of 85°C and 15 seconds.

10. In paragraph 1 or paragraph 5, The above Diol ingredient Bis(2-hydroxyethyl)terephthalate (BHET), isosorbide, neopentyl glycol, ethylene glycol, cyclohexanedimethanol, 1,2-propanediol, 1,3-propanediol, 2-methyl-1,3-propanediol, 2-methylene-1,3-propanediol, 2-ethyl-1,3-propanediol, 2-isopropyl-1,3-propanediol, 2,2-dimethyl-1,3-propanediol, 1,4-butanediol, 2,3-butanediol, 3-methyl-1,5-pentanediol, 3-methyl-2,4-pentanediol, 1,6-hexanediol, 1,2-cyclohexanediol, 1,4-cyclohexanediol, diethylene glycol, 4-(hydroxymethyl)cyclohexylmethyl A heat-shrinkable film comprising at least one selected from the group consisting of 4-(hydroxymethyl)cyclohexanecarboxylate, and 4-(4-(hydroxymethyl)cyclohexylmethoxymethyl)cyclohexylmethanol.

11. In paragraph 1 or paragraph 5, The above dicarboxylic acid component A heat-shrinkable film comprising at least one selected from the group consisting of isophthalic acid, terephthalic acid, dimethyl isophthalate, phthalic acid, dimethyl phthalate, phthalic anhydride, 2,6-naphthalenedicarboxylic acid, dimethyl 2,6-naphthalenedicarboxylate, diphenyl dicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, dimethyl 1,4-cyclohexanedicarboxylate, dimethyl 1,3-cyclohexanedicarboxylate, sebacic acid, succinic acid, isodecylsuccinic acid, maleic acid, maleic anhydride, fumaric acid, adipic acid, glutaric acid, and azelaic acid.

12. In paragraph 1 or paragraph 5, A heat-shrinkable film comprising the above diol and dicarboxylic acid and at least one regenerated monomer.

13. In paragraph 1 or paragraph 5, A heat-shrinkable film, wherein the copolymerized polyester resin comprises at least one selected from the group consisting of antimony (Sb), titanium (Ti), zinc (Zn), germanium (Ge), magnesium (Mg), and manganese (Mn) as a polymerization catalyst.

14. In paragraph 1 or paragraph 5, A heat-shrinkable film comprising the above copolymerized polyester resin, which is uniaxially stretched at a transverse stretch ratio of 1.5 to 6 times or a longitudinal stretch ratio of 1.05 to 6 times.

15. In paragraph 1 or paragraph 5, A heat-shrinkable film comprising the above copolymerized polyester resin, which is biaxially stretched at a transverse stretch ratio of 1.5 to 6 times and a longitudinal stretch ratio of 1.05 to 6 times.

16. In paragraph 1 or paragraph 5, A heat-shrinkable film comprising the above copolymerized polyester resin, which is a single-layer film.

17. In paragraph 1 or paragraph 5, A heat-shrinkable film comprising the above copolymerized polyester resin, which is a multilayer film comprising a substrate layer and a resin layer.

18. In paragraph 1 or paragraph 5, A heat-shrinkable film comprising the above copolymerized polyester resin, the film being manufactured including a step of forming a polyester resin mixture to manufacture an unstretched sheet; and a step of stretching the unstretched sheet.

Images