KR100717942B1 - Polyester films having excellent contractive finishing - Google Patents

Abstract

In the present invention, when manufacturing various plastic containers or shaped articles, etc., the shrinkage finish property at which there are no defects such as deformation of the container after the heat shrinkage, folding of the end portions, shrinkage plaques, generation of wrinkles after shrinkage, or warping. This excellent heat-shrinkable polyester film has an ethylene terephthalate repeating unit of 30 to 94 mol%, a 2-methyl propylene terephthalate repeating unit of 3 to 40 mol%, and a propylene terephthalate repeating unit of 3 to 30 mol A polyester film composed of%, wherein the heat shrinkage in at least one of the longitudinal direction and the width direction of the film exceeds 30% in a hot air at 100 ° C., and the heat shrinkage in the direction orthogonal to the direction is less than 10%. A heat shrinkable polyester film having excellent shrinkage finish, wherein the heat shrinkable polyester film of the present invention is used for coating a container When used as such, not at all of the folded end portion, and a half shrinkage occurs, the generation of wrinkles after shrinkage, and distortion of, and provides a new heat-shrinkable polyester films that can talk to improve productivity in the polymerization reaction.

Description

    Polyester film having excellent contractive finishing

 The present invention is to produce a variety of containers, plastic bottles or rod-shaped molded articles, such as the deformation of the container after heat shrinkage, the folding of the ends, shrinkage half, shrinkage that does not occur at all, such as the generation of wrinkles, distortion, etc. The present invention relates to a heat-shrinkable polyester film having excellent finish, and to a heat-shrinkable polyester film having properties suitable for coating, binding, or exterior use, and particularly, caps and bodies thereof. , Heat shrinkable polyester film with excellent shrinkage finish that covers part or entire surface of shoulder and is suitable for marking, protection, and binding, and improves product value, and reformed for use in integrated packaging. It is about.

      Conventionally, heat shrinkable films, such as polyvinyl chloride, polystyrene, polyethylene, and polypropylene, have been used for such a purpose, and these are covered with tubes in the form of tubes, or packaged and thermally contracted. However, these films are poor in heat resistance and are easily melted or ruptured when subjected to Boyle or Retort treatment, and not only have defects that cannot maintain the film state, but also polyvinyl chloride film generates dioxins upon incineration. There is a problem, the polystyrene film has a problem that the natural shrinkage is so large that its dimensions change after storage and printing.

In addition, as a conventional heat-shrinkable polyester film, a polyester obtained from a polyester composition containing terephthalic acid and ethylene glycol as main components and neopentyl glycol (2,2-dimethyl-1,3-propanediol) as a copolymerization component Although films are known, it is particularly difficult to add neopentyl glycol in a solid state at room temperature when preparing a copolyester composition containing neopentyl glycol. In other words, in order to produce a commercially available copolymerized polyester resin, a solid input line must be separately installed. However, in case of using 2-methyl-1,3-propanediol, which is almost similar to the properties of neopentyl glycol and much more productive, a separate facility is used. It is possible to produce copolyester resin immediately without investment. In other words, since it is a liquid at room temperature, existing production equipment can be utilized as it is.

     In addition, when using a copolyester polyester resin containing 2-methyl-1.3-propanediol, an improved heat-shrink polyester film having almost no defects such as folding of ends, generation of shrinkage bands, generation of wrinkles after shrinkage, and distortion may be produced. You can get it.

It is therefore an object of the present invention to provide a heat-shrinkable polyester film that eliminates the above drawbacks.

The heat shrinkable polyester film having excellent shrinkage finishing property of the present invention, when used for container coating or labeling, reduces the shrinkage speed, which is the most important characteristic, and causes end folding, shrinkage spots, wrinkles after shrinkage, warpage, etc. It is of utmost importance that there are no shortcomings. In order to solve this problem, the present invention has 30 to 94 mol% of ethylene terephthalate repeating units, 3 to 40 mol% of 2-methyl propylene terephthalate repeating units, and 3 to 30 mol% of propylene terephthalate repeating units. Shrinkage finish property of having a characteristic that the heat shrinkage in at least one of the longitudinal direction and the width direction of the film exceeds 30% in the hot air at 100 ° C., and the heat shrinkage in the direction orthogonal to the direction is less than 10%. It is to produce this excellent heat-shrinkable co-polyester film.

 In order to achieve the above object, the present invention provides 30 to 94 mole% of ethylene terephthalate repeating units, 3 to 40 mole% of 2-methyl propylene terephthalate repeating units, and 3 to 30 mole of propylene terephthalate repeating units. Shrinkage in which the heat shrinkage in at least one of the longitudinal and widthwise directions of the film exceeds 30% and the heat shrinkage in the direction orthogonal to the direction is less than 10% in a hot air at 100 ° C. It relates to a polyester film having excellent finish.

       In more detail, the copolymerization polyester resin is polymerized by using terephthalic acid or dimethyl terephthalate as the dicarboxylic acid component and ethylene glycol and 2-methyl-1,3-propanediol as the diol component, followed by copolymerization. The polyester, polytrimethylene terephthalate resins and polyethylene terephthalate resins are blended and melt-extruded at an appropriate mixing ratio, and then manufactured into a sheet, which is stretched in at least one of longitudinal or transverse directions to repeat the above units. To prepare a heat-shrinkable polyester film having a.

      However, a copolymerization method may be used in addition to the blending method as described above. For example, terephthalic acid or dimethyl terephthalate is used as the dicarboxylic acid component, and ethylene glycol, 2-methyl-1,3-propanediol, 1,3-propanediol is copolymerized as the diol component, and then a chip is used. A state is made, and it is melt-extruded to form a sheet, which is then stretched in at least one of longitudinal or transverse directions to obtain a heat shrinkable polyester film having a repeating unit as described above.

 It is preferable that the polyester film excellent in shrinkage finishing property of the present invention contains 3 to 40 mol% of 2-methylpropylene terephthalate repeating units having the structure of the following formula (1) relative to the total components. When the 2-methylpropylene terephthalate repeating unit is less than 3 mol%, the heat shrinkage rate of the film during the heat treatment is low, so that when the bottle is coated, a flaw is likely to occur in the shoulder portion of the bottle due to shrinkage and sterilization treatment.

In addition, when the 2-methylpropylene terephthalate repeating unit exceeds 40 mol%, the thermal contraction rate is too fast, causing problems such as folding of the ends, generation of shrinkage plaques, generation of wrinkles after shrinkage, and distortion.

[Formula 1]

n is a positive integer.

 In the present invention, the heat-shrinkable polyester film preferably contains 3 to 30 mol% of propylene terephthalate repeating units having the structure of the following general formula (2).

When the propylene terephthalate repeating unit is less than 3 mol%, the heat shrinkage rate of the film is lowered, so when the bottle label is used, the shoulder portion of the bottle is likely to loosen, and the propylene terephthalate repeating unit is 30 If the molar percentage is exceeded, the heat shrinkage speed is too high, and thus there are problems such as folding of the ends, occurrence of shrinkage spots, wrinkles after shrinkage, and distortion.

[Formula 2]

n is a positive integer.

In the present invention, the heat-shrinkable polyester film preferably contains 30 to 94 mol% of ethylene terephthalate repeating units having the structure of the following general formula (3).

If the ethylene terephthalate repeating unit is less than 30 mol%, the shrinkage finish is poor because the heat shrinkage rate is too fast, and if the ethylene terephthalate repeating unit exceeds 94 mol%, it is difficult to give sufficient heat shrinkage.

[Formula 3]

n is a positive integer.

 In the present invention, the heat shrinkage rate is greater than 30% in the hot air at 100 ° C in at least one of the longitudinal direction or the transverse direction of the heat-shrinkable polyester film, and the heat shrinkage in the direction orthogonal to the direction is 100 ° C. Should be less than 10%.

 In the present invention, a terephthalic acid or dimethyl terephthalate is a main component of the dicarboxylic acid component, and an ethylene glycol, 2-methyl-1,3-propanediol, and 1,3-propanediol are the main components of the diol component. Other components can be added within the range which does not affect the characteristic of a polyester film. For example, the dicarboxylic acid component isophthalic acid, 2,6-naphthalenedicarboxylic acid, sebacic acid, adipic acid, diphenyldicarboxylic acid, 5-tert-butyl butylisophthalic acid, 2,2, 6,6-tetramethyldiphenyl-4,4-dicarboxylic acid, 1,1,3-trimethyl-3-phenylindan-4,5-dicarboxylic acid, 5-sodium sulfoisophthalic acid, trimellitic acid, Compounds such as oxalic acid, malonic acid, succinic acid, glutaric acid, fimer acid, azelaic acid, pyromellitic acid, 1,4-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, or esters thereof The diol component may include diethylene glycol, triethylene glycol, hexanediol, pentanediol, diol of 2,2- (4-oxyphenol) propane derivative, xylene glycol, butanediol, 1,4- Cyclohexanedi methanol, 1,3-cyclohexanedimethanol, 2,2-bis (4-hydroxyphenyl) propane, bis (4-hydroxyphenyl) sulfone, polytetra Ethylene glycol, may contain components such as polyethylene glycol.

According to the present invention, lubricants such as titanium dioxide, silica, kaolin, calcium carbonate, alumina, zirconia, zeolite and organic particles may be added as necessary, and heat stabilizers, antioxidants, sunscreens, antibacterial agents, antistatic agents, flame retardants and the like may be added. It may also include. Moreover, intrinsic viscosity preferable as a film base material is 0.5-1.3 dl / g.

  Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples.

The present invention is also not limited in scope by the following examples. In addition, the method for evaluating the properties of the films prepared in the following Examples and Comparative Examples is as follows.

(1) Heat Shrinkage:

The shrinkage film was cut and sampled in the longitudinal or transverse direction with a width of 15 mm in the direction to be measured, and the indication lines were recorded at intervals of 200 mm in the longitudinal direction, and then the sample was heated in a hot air at 100 ° C. for 1 minute to measure the shrinkage rate. This was repeated 20 times to obtain an average value, which was defined as thermal shrinkage.

(2) wrinkles:

1,3-dioxolane was applied on one side of the shrink film to a width of about 2 mm, and the film was then rounded and joined to the other end to form a cylindrical tube having a diameter of 14.9 cm. After it is inserted into the water, it is shrunk for 10 seconds in hot water at 80 ° C and then taken out. If the film having 0 to 5 wrinkles of 5 mm or more is represented by ○, the film having 6 to 10 is represented by △, and the film having 11 or more wrinkles is represented by X.

(3) Shrinkage disc (shrinkage defect):

1,3-dioxolane was applied on one side of the shrink film to a width of about 2 mm, and the film was then rounded and joined to the other end to form a cylindrical tube having a diameter of 14.9 cm. After it is inserted into the water, it is shrunk for 10 seconds in hot water at 80 ° C and then taken out. At this time, when there is no shrinkage plaque at all, it is indicated by ○, and when it is not a practical problem, it is indicated by △. When the shrinkage plaque is severe and undesirable as a label, it is indicated by X.

(4) End Sliding phenomenon:                     

1,3-dioxolane is applied on one side of the shrink film to a width of about 2 mm, and then the film is rounded and joined to the other end to form a cylindrical tube of 14.9 cm in diameter. After inserting into a 4cm wide PET bottle and shrinking it for 10 seconds in hot water at 80 ℃, the degree of bending of the upper or lower part of the tube is bowed, as shown in Figure 1 below. The degree of end burnup is evaluated by h. At this time, if the end sowing phenomenon occurs at the top and bottom at the same time, the larger value is applied.

 (5) Loose:

1,3-dioxolane was applied on one side of the shrink film to a width of about 2 mm, and the film was then rounded and joined to the other end to form a cylindrical tube having a diameter of 14.9 cm. After it is inserted into the water, it is shrunk for 10 seconds in hot water at 80 ° C and then taken out. At this time, when there is no looseness at all, it is indicated by ○, and when it is not a practical problem, it is indicated by △, and when it is not preferable because of the looseness, it is indicated by X.

Synthesis Example 1

After 2000 kg of dimethyl terephthalate and 1280 kg of ethylene glycol are added to the reaction tube, 0.08 wt% of manganese acetate is added to the dimethyl terephthalate. After slowly increasing the temperature to 240 ° C, the distilled methanol was removed, and after completion of the transesterification reaction, trimethyl phosphate was added 0.03 wt% to dimethyl terephthalate as a heat stabilizer, and 5 minutes later, antimony trioxide was added 0.03 wt% to dimethyl terephthalate. Then stirring was continued for another 5 minutes. The oligomeric mixture was transferred to another reactor equipped with a vacuum equipment, and then reacted while raising the temperature from 250 ° C to 280 ° C to synthesize polyethylene terephthalate resin (PET) having an intrinsic viscosity of 0.6.

 Synthesis Example 2

 After 2000 kg of dimethyl terephthalate and 1600 kg of propylene glycol were added to the reaction tube, tetrabutyl titanate was added to 0.05wt% of dimethyl terephthalate,

The methanol is distilled out while gradually raising the temperature to 240 ° C., and after completion of the transesterification reaction, trimethyl phosphate is added 0.045 wt% to dimethyl terephthalate as a heat stabilizer, and after 5 minutes, 0.03 wt of antimony trioxide to dimethyl terephthalate. % Was added and stirring was continued for another 5 minutes. The mixture in the oligomer state is transferred to another reactor equipped with a vacuum equipment, and then reacted while raising the temperature from 250 ° C to 280 ° C to synthesize polytrimethylene terephthalate resin (PTT) having an intrinsic viscosity of 0.8.

 Synthesis Example 3

1000 kg of dimethyl terephthalate, 450 kg of ethylene glycol and 280 kg of 2-methyl-1,3-propanediol were added to the reaction tube, and 0.08 wt% of manganese acetate was added to the dimethyl terephthalate. The methanol is distilled out while gradually raising the temperature to 240 ° C, and after completion of the transesterification reaction, trimethyl phosphate is added 0.03 wt% to dimethyl terephthalate as a heat stabilizer, and after 5 minutes, 0.03 wt% of antimony trioxide is added to dimethyl terephthalate. And it stirred for 5 minutes. The oligomeric mixture was transferred to another reactor equipped with a vacuum facility, and then copolymerized polyester resin (MPD COPET) was made while heating up from 250 ° C to 280 ° C. The intrinsic viscosity of this copolyester was 0.7, the composition was made into 100 mol% of dimethyl terephthalate, 60 mol% of ethylene glycol, and 40 mol% of 2-methyl- 1, 3- propanediol.

 Example 1

30 wt% of polyethylene terephthalate resin (PET), 10 wt% of polytrimethylene terephthalate resin (PTT), and 60 wt% of copolyester polyester resin (MPD COPET) are uniformly melt-extruded at 260 to 300 ° C to apply electrostatic force through a T die. By the method, an unoriented sheet having a thickness of 150 to 200 µm was prepared. The sheet thus prepared was stretched 3 to 4 times in the transverse direction to prepare a heat shrinkable polyester film having a thickness of 50 um.

EXAMPLES 2-4

 Polyethylene terephthalate resin (PET), polytrimethylene terephthalate

The mixing ratio of the resin (PTT) and the copolyester resin (MDP COPET) was the same as in Example 1 except that Table 1 was used.

 Comparative Example 1

The mixing ratio of polyethylene terephthalate resin (PET), polytrimethylene terephthalate resin (PTT), and copolyester resin (MDP COPET) was the same as in Example 1 except that the mixing ratio was as shown in Table 1.

 Comparative Example 2

 1000 kg of dimethyl terephthalate, 400 kg of ethylene glycol, and 350 kg of 2-methyl-1,3-propanediol were added to the reaction tube, and 0.08 wt% of manganese acetate was added to the dimethyl terephthalate. The methanol is distilled out while gradually raising the temperature to 240 ° C. After the transesterification reaction, trimethyl phosphate is added 0.03 wt% to dimethyl terephthalate as a heat stabilizer. % Was added and stirring continued for 5 minutes. The oligomeric mixture was transferred to another reactor equipped with a vacuum equipment, and then a copolymerized polyester resin was produced while raising the temperature from 250 ° C to 280 ° C. The intrinsic viscosity of this copolyester was 0.7, the composition was set to 100 mol% of dimethyl terephthalate, 50 mol% of ethylene glycol, and 50 mol% of 2-methyl- 1, 3- propanediol. This copolyester resin was melt-extruded at 260-300 degreeC, and the unstretched sheet whose thickness is 150-200 micrometers was produced.

The sheet was preheated at 90 to 110 ° C. and stretched 3 to 4 times in the transverse direction at 80 to 100 ° C. to prepare a 50 um heat-shrinkable polyester film.

 Comparative Examples 3 to 6

The mixing ratio of polyethylene terephthalate resin (PET), polytrimethylene terephthalate resin (PTT), and copolyester resin (MDP COPET) was the same as in Example 1 except for mixing.

TABLE 1

level PET (wt%) PTT (wt%) MPD COPET (wt%) Example 1 30 10 60 Example 2 50 10 40 Example 3 50 20 30 Example 4 30 20 50 Example 5 5 0 95 Comparative Example 1 83 10 7 Comparative Example 2 0 0 100 Comparative Example 3 93 2 5 Comparative Example 4 55 35 10 Comparative Example 5 0 60 40 Comparative Example 6 90 5 5

The result of measuring the Example and the comparative example by the characteristic evaluation method is shown in Table 2 below.

TABLE 2

level Heat Shrinkage (%) Vertical / Horizontal wrinkle Contraction End rise (mm) Looseness Example 1 3/70 ○ ○ 0 ○ Example 2 1/60 ○ ○ 0 ○ Example 3 3/68 ○ ○ 0 ○ Example 4 4/75 ○ ○ 0 ○ Example 5 3/73 ○ ○ 0 ○ Comparative Example 1 1/25 - - - × Comparative Example 2 6/88 × × 7 ○ Comparative Example 3 1/23 - - - × Comparative Example 4 4/86 × × 8 ○ Comparative Example 5 6/95 × × 12 ○ Comparative Example 6 1/15 - - - ×

The present invention has no problems such as folding of the ends, whitening, shrinkage, wrinkles after shrinkage, warpage, etc. when the heat-shrinkable polyester film is used for container coating or labeling. In order to improve the speed, the shrinkage finish property comprised of 30-94 mol% of ethylene terephthalate repeating units, 3-40 mol% of 2-methylpropylene terephthalate repeating units, and 3-30 mol% of propylene terephthalate repeating units This excellent heat shrinkable polyester film is obtained.

Claims (1)

 Terephthalic acid or dimethyl terephthalate is used as the dicarboxylic acid component and ethylene glycol is used as the diol component to polymerize the copolymerized polyester resin, and the copolymerized polyester resin, the polytrimethylene terephthalate resin and the polyethylene terephthalate resin are blended. This is melted and extruded, or copolymerized using terephthalic acid or dimethyl terephthalate as dicarboxylic acid component and ethylene glycol, 1,3 propanediol and 2-methyl-1,3-propanediol as diol component. In melt extrusion of an ester resin to produce a polyester film,        3-40 mol% of 2-methylpropylene terephthalate repeating units which have a structure of following formula (1), 3-30 mol% of the propylene terephthalate repeating units which have a structure of following formula (2), and the following 30-94 mol% of ethylene terephthalate repeating units which have a structure of Formula (3) are contained, and the thermal contraction rate in at least one direction of a longitudinal direction or a transverse direction exceeds 30% in the hot air of 100 degreeC, and the direction The polyester film excellent in shrinkage finish property, characterized in that the heat shrinkage in the direction orthogonal to and less than 10%.

Equation (1) Where n is a positive integer.

Equation (2)     Where n is a positive integer.

..... Equation (3)   Where n is a positive integer.