KR100614622B1 - A high shrinkage and drawn polyester film, and a process of preparing for the same - Google Patents

Abstract

The present invention relates to a polyester-based high shrink stretch film mainly used for container labels, 10 to 69% by weight polytrimethylene terephthalate (PTT), 1 to 30% by weight polyethylene terephthalate (PET) and dicarboxylic 30 to 60% by weight of a glycol modified copolyester (PETG) prepared by the polycondensation reaction of an acid component with a glycol component composed of ethylene glycol (EG) and 1,4-cyclohexanedimethanol (CHDM) is blended. Spherical inorganic particles having a short diameter / long diameter ratio of 0.8 to 1.0 are contained in an amount of 0.01 to 0.3% by weight (relative to the total weight of the resin), and have a haze of 4.0 or less and a copper friction coefficient of 0.4 or less. The film of the present invention has a longitudinal hot air shrinkage of 5% or less and a transverse hot air shrinkage of 50 to 70%. The film of the present invention is excellent in heat shrinkage characteristics such as stability over time, slip properties and transparency, suitable for container label applications.

Polyester, Film, Stretched, High Shrinkable, Container Label, Blend, 1,4-Cyclohexanedimethanol, Polytrimethylene Terephthalate, Slip, Heat Shrinkable

Description

Polyester type high shrink stretched film and manufacturing method thereof {A high shrinkage and drawn polyester film, and a process of preparing for the same}             

The present invention relates to a polyester-based high shrink stretched film mainly used as a shrink film for container labels and a method for producing the same.

Polyvinyl chloride (hereinafter referred to as "PVC") shrink film, polyethylene terephthalate (hereinafter referred to as "PET") shrink film, and stretched polystyrene (hereinafter referred to as "OPS") shrink film are widely used as the film for labeling of containers. have.

The container label made of the shrink film is made larger than the container and can be contracted by the heat applied during labeling to improve the unity of the label and the container, and labeling is possible regardless of the shape of the container.

Uniaxial (unidirectional) shrinkage is required for the film for container labels. PVC shrink films are the most widely used shrink film for container labels because of their low cost and easy molding.

However, PVC shrink film is difficult to use in applications that require high shrinkage due to low shrinkage rate, there is a problem that a lot of harmful gases such as dioxin containing chlorine is generated during incineration disposal to pollute the environment. In addition, a lot of additives such as plasticizers are used in the manufacture of PVC, and these additives may also include substances that cause cancer, and thus cannot be used for direct packaging of foods.

In order to solve this problem of PVC shrink film, OPS shrink film is currently being developed and used. The purpose of OPS shrink film is to increase the recycling rate in that the container and the label are the same material when used as the label of the polystyrene container. However, the market did not expand due to poor printability and storage difficulties. In particular, the problem of the natural shrinkage rate of the OPS is a lot of printing failure due to the shrinkage over time during the printing process, the low temperature warehouse such as the refrigerator compartment is essential when storing the film, there is also a problem in transport in summer. In the case of printability, special ink should be used. The more the color, the lower the printability.

Meanwhile, in order to solve various problems of the PVC shrink film or the OPS shrink film, a PET shrink film is developed and used as a container label film. In the case of a PET shrink film, the same material as the container and the label is used to improve recovery and recyclability. It is possible to control the shrinkage rate or shrinkage rate, and can be used not only for general labels but also for covering the entire container. In addition, it has better low temperature shrinkage compared to PVC shrink film, high temperature labeling, and high stiffness, so that it can be used with 10 ~ 25% lower thickness than OPS or PVC shrink film.

The natural shrinkage property of the heat shrinkable film for labeling is a very disadvantageous property, and the polyester-based shrinkage film is advantageous for practical use because its stability over time is superior to other materials.

Existing films may be retort-treated at high temperature, but are not suitable for sterilization due to their low heat resistance. However, polyester-based heat-shrink films have no specific problem in retort treatment or high-temperature sterilization because they have unique heat resistance not found in OPS or PVC. Printing aptitude is possible to apply PVC shrink film ink as it is, and there is no foreign matter compared to PVC and it has good smoothness and vivid multicolor printing is possible.

This polyester-based shrink film is isophthalic acid (IPA) or dimethyl-2,6-naphthalenedicarboxyl as an acid component when polymerizing terephthalic acid (TPA) and ethylene glycol (EG) to produce polyethylene terephthalate. Copolymerization of copolymers prepared in this way, copolymerization of diethylene glycol (DEG) or 1,4-cyclohexanedimethanol (hereinafter referred to as "CHDM") as a glycol component, or blending of copolyesters prepared as such Has been manufactured. However, the conventional polyester-based shrink films have a problem that the post-processing processability is poor due to the lack of slip properties.

The present invention has excellent heat shrinkage characteristics such as stability over time and transparency, polyester-free high shrinkage, which has no problem of environmental pollution, good printability, easy storage, and especially good slip property, thereby improving post processing processability. To provide a stretched film and a method of manufacturing the same.

The polyester-based high shrink stretched film of the present invention for achieving the above object is 10 to 69% by weight of polytrimethylene terephthalate (PTT), 1 to 30% by weight of polyethylene terephthalate (PET) and dicarboxylic acid component and 30 to 60% by weight of glycol modified copolyester (PETG) prepared by polycondensation reaction of glycol component composed of ethylene glycol (EG) and 1,4-cyclohexanedimethanol (CHDM) It is characterized by containing 0.01 to 0.3% by weight of spherical inorganic particles having a ratio of 0.8 to 1.0.

The film of the present invention has a haze of 4.0 or less, a copper friction coefficient of 0.4 or less, a transverse hot air shrinkage rate (100 ° C. × 30 seconds) of 50 to 70%, and a longitudinal hot wind shrinkage rate (100 ° C. × 30 seconds). ) Is 5% or less.

Hereinafter, the present invention will be described in detail.

First, the present invention is 10 to 69% by weight of polytrimethylene terephthalate (PTT), 1 to 30% by weight of polyethylene terephthalate (PET) and dicarboxylic acid component and ethylene glycol (EG) and 1,4-cyclohexane in the extruder 30 to 60% by weight of glycol modified copolyester (PETG) prepared by the polycondensation reaction of glycol component composed of dimethanol (CHDM) is added and blended, and the short diameter / long diameter ratio of the total resin weight is 0.8 to 1.0. 0.01-0.3 weight% of spherical inorganic particles are added, and these are melted and extruded. In this case, the amount of CHDM used during the polymerization of the glycol modified copolyester (Glycol Modified Copolyester) is preferably 10 to 30% by weight based on the total amount of EG.

The polytrimethylene terephthalate (hereinafter referred to as "PTT") has a melting point of 226.6 ° C, a glass transition temperature of 43.4 ° C, a crystallization rate of 166.1 seconds (190 ° C), and a density of 1.33 g / cm 3. The polyethylene terephthalate (hereinafter referred to as "PET") has a melting point of 253.7 ° C, a glass transition temperature of 75.8 ° C, a crystallization rate of 211.6 seconds (210 ° C), and a density of 1.40 g / cm 3. There is no melting point of the glycol modified copolyester (hereinafter referred to as "PETG"), the glass transition temperature is 81 DEG C, and the crystallization rate is amorphous.

When blending, the PET content exceeds the above range, and the shrinkage property of the film is insufficient. When the PETG content exceeds the above range, natural shrinkage occurs over time, resulting in poor appearance of the film.

The present invention is characterized in that in order to improve the slip properties of the stretched high shrink film, spherical inorganic particles having excellent antiblocking effect are added during the preparation of the blending resin. In this case, the spherical inorganic particles to be added have a short diameter / long diameter ratio of 0.8 to 1.0, and the amount of the spherical inorganic particles to be added is appropriately adjusted in consideration of slip and haze levels required for the film within the range of 0.01 to 0.3% by weight based on the weight of the resin. When the short diameter / long diameter ratio of the spherical inorganic particles is out of the above range, the protrusions formed on the surface of the film become nonuniform, and it is difficult to obtain good slipperiness.

The extruded film is quenched continuously below the glass transition temperature (Tg) of the resin, and then transversely stretched at a stretching ratio of 3.5 to 5.0 times at a temperature of 45 to 85 ° C, and (lateral stretching temperature -5 ° C) to ( A polyester-based high shrink stretched film was prepared by heat treatment at a temperature of transverse stretching temperature of + 10 ° C. When the stretching temperature and the heat treatment temperature are higher than the above ranges, the thermal contraction rate of the film is lowered and high shrinkage characteristics are hardly obtained.

The film of the present invention thus produced has a hot air shrinkage of 5% or less in the longitudinal direction, 50 to 70% of the hot air shrinkage in the transverse direction. The coefficient of kinetic friction is 0.4 or less and the haze (turbidity) of the film is 4.0 or less.

Various physical properties of the film in the present invention was evaluated by the following method.

Lateral and longitudinal hot wind shrinkage (%)

Heat-treat the film specimens of 20 cm length x 20 cm width for 30 seconds at 100 ° C and substitute the transverse and longitudinal lengths before and after the heat treatment in the equation below to obtain the hot air shrinkage.

×100Hot Air Shrinkage (%) =

× 100

Dynamic Friction Coefficient

The coefficient of kinetic friction of the film surface is measured by ASTM D 1904 method.

Haze (turbidity)

The turbidity of the film is measured by the ASTM D 1004 method.

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples. However, the present invention is not limited only to the following examples.

Example 1

PTT 30% by weight, PET 30% by weight and PETG 40% by weight were added to the extruder and 0.2% by weight of spherical silica dioxide having a short diameter of 0.9 μm and a long diameter of 1 μm (short diameter / long diameter ratio: 0.9) to the total weight of the resin. Are added and they are melted and mixed and extruded onto the film. Subsequently, the extruded film is quenched at 30 ° C. and transversely stretched at a draw ratio of 4.0 times in a tenter type transverse stretching machine. At this time, the lateral stretching temperature is 75 ° C. Subsequently, the transversely stretched film was heat-treated at 80 ° C. to prepare a polyester-based stretched film having a thickness of 40 μ. The results of evaluating the physical properties of the prepared stretched film are shown in Table 2.

Example 2 to Example 3 and Comparative Example 1 to Comparative Example 4

A polyester-based stretched film was manufactured in the same process as in Example 1 except that the film production conditions were changed as shown in Table 1. The results of evaluating the physical properties of the prepared stretched film are shown in Table 1.

Manufacture conditions division Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Resin composition (% by weight) PTT 30 30 20 20 10 30 20 PET 30 20 20 50 20 30 20 PETG 40 50 60 30 70 40 60 Particle (SiO ₂ ) shape and content Short diameter (㎛) 0.9 1.6 2.85  Indeterminate  Indeterminate  Indeterminate  Indeterminate Long diameter (㎛) 1.0 2.0 3.0 Short diameter / long diameter ratio 0.9 0.8 0.95 Content (% by weight) 0.2 0.1 0.05 0.05 0.05 0.05 0.05 Lateral Stretch Condition Temperature (℃) 75 80 85 90 80 100 110 Elongation ratio 4.0 4.3 4.5 3.0 4.0 3.0 4.0 Heat treatment temperature (℃) 80 80 80 85 85 100 100

Film property evaluation result division Hot air shrinkage rate (%) Haze Coefficient of friction Film appearance Post-processability Longitudinal direction Transverse Example 1 -0.5 57 3.5 0.38 Good Good Example 2 0.8 61 3.0 0.35 Good Good Example 3 2.0 68 3.5 0.32 Good Good Comparative Example 1 6 40 4.2 0.5 Good Bad Comparative Example 2 11 65 3.8 0.55 Bad Bad Comparative Example 3 2.0 32 3.8 0.44 Good Bad Comparative Example 4 1.2 43 3.8 0.48 Good Bad

The present invention is composed of a polyester-based resin is very excellent in heat shrinkage characteristics, transparency, printability, storage properties. In addition, the present invention does not have a problem of environmental pollution during incineration waste, it contains spherical inorganic particles is particularly excellent in slip properties. As a result, the present invention can be greatly improved post-processing fairness.

Claims (5)

Polytrimethylene terephthalate (PTT) 10-69% by weight, polyethylene terephthalate (PET) 1-30% by weight and dicarboxylic acid component with ethylene glycol (EG) and 1,4-cyclohexanedimethanol (CHDM) 30 to 60% by weight of glycol modified copolyester (PETG) prepared by the polycondensation reaction of the glycol component is composed, and 0.01 to 0.3% by weight of spherical inorganic particles having a short diameter / long diameter ratio of 0.8 to 1.0 It contains, Haze is 4.0 or less and the polyester friction coefficient is 0.4 or less, The polyester-type high shrinkage stretched film characterized by the above-mentioned. The polyester-based high shrink stretched film according to claim 1, wherein the film has a transverse hot air shrinkage (100 占 폚 x 30 seconds) of 50 to 70%. The polyester type high shrink stretched film according to claim 1, wherein the longitudinal hot air shrinkage (100 占 폚 x 30 seconds) of the film is 5% or less. The polyester-based high shrink stretch film according to claim 1, wherein 1,4-cyclohexanedimethanol (CHDM) content in the glycol component of glycol modified copolyester (PETG) is 10 to 30% by weight. Polytrimethylene terephthalate (PTT) 10-69% by weight, polyethylene terephthalate (PET) 1-30% by weight and dicarboxylic acid component with ethylene glycol (EG) and 1,4-cyclohexanedimethanol (CHDM) 0.01-0.3% by weight of spherical inorganic particles having a short diameter / long diameter ratio of 0.8-1.0 in a polyester resin in which 30-60% by weight of glycol modified copolyester (PETG) prepared by the polycondensation reaction of the glycol component composed Melted and extruded by adding to the total weight of the resin), followed by quenching to below the glass transition temperature (Tg) of the resin, and then stretching laterally at a draw ratio of 3.5 to 5.0 times at a temperature of 45 to 85 ° C. Process for producing a polyester-based high shrink stretch film, characterized in that the heat treatment at a temperature of -5 ℃) ~ (lateral stretching temperature +10 ℃).