KR20170009003A

KR20170009003A - Heat-shrinkable laminated film and heat-shrinkable label using same

Info

Publication number: KR20170009003A
Application number: KR1020150100281A
Authority: KR
Inventors: 김철규; 김용득; 전민희; 김성도
Original assignee: 에스케이씨 주식회사
Priority date: 2015-07-15
Filing date: 2015-07-15
Publication date: 2017-01-25
Also published as: KR101733186B1

Abstract

The present invention relates to a heat-shrinkable multilayer film having excellent heat shrinkage and solvent adhesion, and a packaging material or label including the same, wherein the heat shrinkable multilayer film according to the present invention is excellent in shrinkage characteristics, solvent adhesion, peel strength Can be used as labels for beverages, medical containers, dry batteries or the like and for packaging films for various articles and the like.

Description

HEAT SHRINKABLE LAMINATED FILM AND HEAT-SHRINKABLE LABEL USING SAME Technical Field [1] The present invention relates to a heat-

The present invention relates to a heat-shrinkable laminated film having excellent heat shrinkage and solvent adhesion, and packaging materials or labels containing the same.

The heat-shrinkable film is generally used for packaging of plastic containers, glass bottles, batteries or electrolytic capacitors, and packaging containers, as well as for stationary or multiple containers for integrated packaging or close packing.

Polyester has been attracting attention as a material of heat shrinkable film which can replace polyvinyl chloride as an environmentally friendly material which is easy to recycle as a label as the use amount of PET (PET) container increases sharply. The heat-shrinkable polyester film has properties such as high heat resistance, weather resistance, easy burning, excellent printability, and is widely used for packaging and labeling in beverage containers such as PET bottles and other types of containers. Conventionally, in order to label a cylindrical container such as a beverage container or the like, a polyester film is cut into a predetermined size, and then both ends are rounded with an adhesive solvent, and then the container is covered with a container to shrink the container . Therefore, for efficient labeling, shrinkage properties and solvent adhesion required for heat-shrinkable films should be realized.

In the conventional heat shrinkable polyester film, a material made of a two-component system such as neopentyl glycol (NPG), diethylene glycol (DEG) and the like is added in order to realize the physical properties required in the heat shrinkable film. However, in this case, due to the chemical resistance of the material, crystallization of the polymer constituting the film is induced by induction of crystallization in the stretching process during the film production process, and the adhesiveness is lowered by the organic solvent when the heat is fixed have.

On the other hand, U.S. Patent No. 7935401 discloses a composition comprising a skin layer comprising a glycol-modified polyester such as polyethylene terephthalate glycol (hereinafter referred to as PETG) and a base layer comprising an alpha-olefin / cyclic-olefin copolymer Discloses a heat-shrinkable laminated polyester film.

However, since the above-mentioned film uses a base layer having a glass transition temperature lower than 50 deg. C, it has a high natural shrinkage ratio in a natural state and at room temperature, and may cause shrinkage during film flow.

U.S. Patent No. 7935401

Accordingly, an object of the present invention is to provide a heat-shrinkable multilayer polyester film having excellent heat shrinkage and solvent adhesion.

Another object of the present invention is to provide a heat-shrinkable label using the film.

In order to achieve the above object,

A three-layer coextruded structure of a first outermost layer / a middle layer / a second outermost layer,

Wherein the first outermost layer and the second outermost layer each comprise a dicarboxylic acid repeating unit containing terephthalic acid (TPA) and a polyester resin comprising a diol repeating unit containing 1,4-cyclohexanedimethanol (CHDM) Lt; / RTI >

Wherein the center layer comprises a polyester resin comprising a dicarboxylic acid repeat unit comprising TPA and a diol repeat unit comprising neopentyl glycol (NPG), diethylene glycol (DEG) and ethylene glycol (EG) , And a heat-shrinkable laminated film.

In order to achieve the other object, the present invention provides a packaging material or label comprising the heat-shrinkable laminated film.

The heat-shrinkable laminated film of the present invention can exhibit both excellent shrinkage characteristics and seaming characteristics required for a heat-shrinkable film, and thus can be used as a label for wrapping, medical containers, dry batteries or the like, . &Lt; / RTI >

In the present invention, in the case where each film, film, panel or layer is described as being formed "on" or "under" of each film, film, panel, The terms " on "and" under "all include being formed either" directly "or" indirectly "through" another element ". In addition, the upper and lower standards for each component are described with reference to the drawings. The size of each component in the drawings may be exaggerated for the sake of explanation and does not mean the size actually applied.

Conventional heat-shrinkable polyester resins including NPG, DEG and the like are deteriorated in adhesiveness due to organic solvents during heat fixation due to their crystallinity. In the present invention, in order to solve such a problem of lowering the adhesiveness, a polyester resin containing CHDM is formed on both sides of a conventional polyester resin including NPG and DEG by a co-extrusion process to form a three-layer laminated film A heat shrinkable laminated film having excellent heat shrinkage and solvent adhesive strength was produced.

Accordingly, the present invention provides a three-layer coextruded structure of a first outermost layer / a middle layer / a second outermost layer, wherein each of the first outermost layer and the second outermost layer is a dicarboxylic acid repeating layer containing terephthalic acid (TPA) Unit and a diol repeating unit comprising CHDM, wherein the center layer comprises a dicarboxylic acid repeating unit comprising TPA and a diol repeating unit comprising NPG, DEG and EG A heat-shrinkable laminated film comprising a polyester resin is provided.

Wherein each of the first outermost layer and the second outermost layer comprises from 0.5 to 100 mol%, from 0.5 to 70 mol%, from 0.5 to 50 mol%, from 0.5 to 30 mol%, or from 0.5 to 100 mol%, based on the total diol repeating units, 15 mole%; A polyester resin comprising a polyester resin obtained by polymerizing 80 to 100 mol%, 85 to 100 mol%, 90 to 100 mol%, or 95 to 100 mol% of TPA repeating units based on the total dicarboxylic acid repeating units Layer.

Each of the first outermost layer and the second outermost layer may further include ethylene glycol (EG) as a diol repeating unit. Wherein each of said first outermost layer and second outermost layer comprises 0 to 99.5 mol%, 30 to 99.5 mol%, 50 to 99.5 mol%, 70 to 99.5 mol%, or 85 To 99.5 mol%.

The first outermost layer and the second outermost layer may each contain, in addition to EG, 1,3-propanediol, 1,2-octanediol, 1,3-octanediol, 2,3-butanediol, Butanediol, 1,5-pentanediol, 2,2-dimethyl-1,3-propanediol (i.e. neopentyl glycol), 2-butyl- Diethylene-1,5-pentanediol, 3-methyl-1,5-pentanediol, 1,1-dimethyl- 4-cyclohexane dimethanol, and combinations thereof. However, the present invention is not limited thereto.

The first outermost layer and the second outermost layer may each contain, in addition to TPA, an aromatic dicarboxylic acid such as isophthalic acid (IPA), dimethyl terephthalic acid, dimethyl isophthalic acid and naphthalene-2,6-dicarboxylic acid, adipic acid alicyclic dicarboxylic acids such as acetic acid, azelaic acid, oxalic acid, succinic acid and glutaric acid, and combinations thereof, and a dicarboxylic acid repeating unit But the present invention is not limited thereto.

Each of the first outermost layer and the second outermost layer may be, for example, polyethylene terephthalate (PET), polyethylene terephthalate glycol (PETG), or polycyclohexylene dimethylene terephthalate glycol (PCTG) But is not limited thereto.

The PETG may be a polyester resin obtained by polymerizing TPA as a repeating unit of dicarboxylic acid and CHDM and ethylene glycol as a diol repeating unit.

The first outermost layer and the second outermost layer may be the same or different.

Since the first outermost layer and the second outermost layer are made of a polyester layer containing CHDM, it is possible to compensate for the weakening of the adhesiveness due to the organic solvent caused by the crystallization occurring in the printing process and the like.

The center layer is a polyester layer comprising a polyester resin obtained by polymerizing TPA as a dicarboxylic acid repeating unit and NPG, DEG and EG as a diol repeating unit.

More specifically, the center layer comprises 80 to 100 mol%, 85 to 100 mol%, 90 to 100 mol%, or 95 to 100 mol% of TPA repeating units based on the total dicarboxylic acid repeating units; 1 to 30 mol%, 1 to 25 mol%, 1 to 20 mol%, or 1 to 17 mol%, DEG repeating unit, 0.5 to 10 mol%, 0.5 to 6 mol%, based on the total diol repeating units, From 0.5 to 5 mol%, from 0.5 to 4 mol%, or from 0.5 to 3 mol%, and from 60 to 90 mol%, from 70 to 90 mol%, from 70 to 80 mol%, or from 75 to 80 mol% Is a polyester layer containing a polyester resin.

In addition to TPA, the center layer may be formed of an aromatic dicarboxylic acid such as IPA, dimethyl terephthalic acid, dimethyl isophthalic acid, and naphthalene-2,6-dicarboxylic acid, aliphatic acid such as adipic acid, azelaic acid, oxalic acid, succinic acid, Dicarboxylic acid, and dicarboxylic acid repeating units selected from the group consisting of combinations thereof, but the present invention is not limited thereto.

In addition to NPG, DEG and EG, the center layer may further comprise at least one selected from the group consisting of 1,3-propanediol, 1,2-octanediol, 1,3-octanediol, 2,3-butanediol, Pentanediol, 2-butyl-2-ethyl-1,3-propanediol, 2,2-diethyl-1,5-pentanediol, 2,4- -Methyl-1,5-pentanediol, 1,1-dimethyl-1,5-pentanediol, and combinations thereof. If the component is a component ordinarily used in the art Can be used without limitation.

More specifically, the center layer may contain, in addition to NPG, DEG and EG as diol repeat units, from about 5 mol% to about 9.9 mol% of CHDM repeat units.

The heat-shrinkable laminated film according to the present invention has a structure in which a first outermost layer, a middle layer and a second outermost layer are sequentially laminated, and they can be extruded simultaneously and then drawn by coextrusion.

In the heat-shrinkable laminated film according to the present invention, the first outermost layer, the middle layer and the second outermost layer may have a thickness ratio of 1: 0.5 to 100: 1. At this time, the first outermost layer, the middle layer and the second outermost layer may have a thickness ratio of 1: 0.5 to 100: 1. More specifically, the first outermost layer, the middle layer and the second outermost layer may have a thickness ratio of 1: 0.5 to 50: 1. More specifically, the first outermost layer, the middle layer and the second outermost layer may have a thickness ratio of 1: 1 to 20: 1.

The heat-shrinkable laminated film according to the present invention preferably has a thickness of 5 to 500 mu m and 25 to 300 mu m, for example, 50 to 100 mu m. When the film has a thickness in the above range, it has excellent stretch uniformity. It has excellent heat shrinkage uniformity, ink adhesion, moisture and gas barrier property, crack resistance, and rupture resistance when used for labeling or packaging, Exhibits excellent thermal stability when used as labels for containers that are prone to occur.

The heat-shrinkable laminated film of the present invention can be produced by adding a polymerization catalyst, a dispersing agent, an antiblocking agent, an electrostatic agent, an antistatic agent, an antioxidant, a heat stabilizer and a ultraviolet screening agent widely known in the art within the range not impairing the effects of the present invention For example, 0.001 to 10.0% by weight based on the total weight of the heat-shrinkable laminated film.

The heat-shrinkable laminated film according to the present invention can be produced by the following process.

(a) providing a polyester resin constituting a first outermost layer, a middle layer and a second outermost layer, respectively; (b) co-extruding the resins to produce an unoriented sheet; And (c) stretching the unstretched sheet.

More specifically, first, each polyester resin can be produced by esterification reaction of the corresponding diol component and the corresponding dicarboxylic acid component and solid phase polymerization process according to a conventional method.

These polyester resins are co-extruded (melt extruded) and cooled to produce an unstretched sheet having a laminated structure.

Thereafter, the unstretched sheet is stretched in either one or both of the longitudinal direction (machine direction) and the width direction (tenter direction), and is heat-set so that the polyester laminated film can be produced.

The melt extrusion is preferably performed at a temperature ranging from Tm + 30 占 폚 to Tm + 60 占 폚. If the temperature of the extruder is lower than Tm + 30 占 폚 in the melt extrusion process, the melt will not be smoothly melted and the viscosity of the extrudate will increase to lower the productivity. Conversely, if the temperature exceeds Tm + 60 占 폚, the molecular weight of the resin decreases due to depolymerization due to thermal decomposition, A problem may arise. Further, it is preferable that the cooling is performed at a temperature of 30 DEG C or less, for example, 15 to 30 DEG C.

The unstretched sheet is uniaxially or biaxially stretched, and may be stretched in one direction, and stretched in another direction or stretched slightly.

The unstretched sheet may be stretched 2.5 to 6 times in the first direction, for example, in the width direction, and 1.5 times or less in the second direction perpendicular to the first direction, for example, in the longitudinal direction. For example, the unstretched sheet may be stretched three to five times in the first direction, e.g., in the width direction, and 1.3 times or less in the second direction perpendicular to the first direction, for example, in the longitudinal direction . Alternatively, the unstretched sheet may be stretched 3.5 to 4.5 times in the first direction, for example, in the width direction, and 1.2 times or less in the second direction perpendicular to the first direction, for example, in the longitudinal direction.

The stretching temperature is preferably in the range of Tg + 5 deg. C to Tg + 80 deg. C, and the lower the Tg, the better the stretchability, but the breakage may occur. In particular, in order to improve the brittleness, a stretching temperature range of Tg + 10 deg. C to Tg + 50 deg. C is preferable.

After initiating the heat setting, the film is relaxed in the longitudinal and / or width direction, and the stretched sheet can be heat set at a temperature of 70 to 260 캜, for example, 90 to 150 캜.

In one embodiment, the heat-shrinkable laminated film according to the present invention has a heat shrinkability of 20% or more, 20% or more, 90% or 30% or less when heat-treated in at least one axial direction, 80%, 40% to 70%, or 50% to 60%.

In another embodiment, the heat-shrinkable laminated film according to the present invention has a peel strength of 100 to 2,000 gf, 200 to 1,800 gf, 300 to 1,600 gf, and 400 to 1,500 gf .

The heat-shrinkable laminated film according to the present invention is suitable for use as a heat shrinkable label or a packaging material. The heat-shrinkable label or packaging material can preferably be used for the packaging of plastic containers, glass bottles, dry cells or electrolytic capacitors, and for the overall application of packaging containers, as well as for stationary or multiple containers Do.

Accordingly, the present invention provides a packaging material or label comprising the heat-shrinkable laminated film.

The features, structures, effects and the like described in the present invention are included in at least one embodiment of the present invention and are not necessarily limited to only one embodiment. Furthermore, the features, structures, effects and the like illustrated in the embodiments can be combined and modified by other persons having ordinary skill in the art to which the present invention belongs. Therefore, it should be understood that the present invention is not limited to these combinations and modifications.

[Example]

Hereinafter, the present invention will be described in more detail with reference to the following examples. However, the following examples are for illustrative purposes only and are not intended to limit the scope of the present invention.

Production Example 1: Production of outermost polyester resin

After the esterification reaction tube was heated to 200 ° C, ethylene glycol 70 mol%, CHDM 30 mol% and TPA 100 mol% were added, and 0.017 part by weight of manganese acetate was added as a catalyst based on 100 parts by weight of these raw materials and stirred. Then, the mixture was subjected to pressure esterification at a gauge pressure of 0.34 MPa and at 240 ° C, and then the esterification reaction tube was returned to normal pressure. Then, 0.014 part by weight of phosphoric acid was added. Thereafter, the temperature was raised to 260 DEG C over 15 minutes, and 0.012 part by weight of trimethyl phosphate was added as a stabilizer. Subsequently, after 15 minutes, dispersion treatment was carried out with a high-pressure disperser. After 15 minutes, the obtained esterification reaction product was transferred to a polycondensation reaction tube, and polycondensation reaction was carried out at 280 DEG C under reduced pressure.

After completion of the polycondensation reaction, the mixture was filtered through a nylon filter having a cut-off size of 95% at a size of 5 탆, extruded from the nozzle into a strand shape, and cooled and solidified using cooling water previously subjected to filtration treatment (pore size: And cut into pellets to obtain a desired polyester, that is, a glycol-modified polyethylene terephthalate (hereinafter referred to as PETG) resin chip.

Manufacturing example 2: Center floor Production of polyester resin- (1)

Except that 17% by mole of NPG, 5% by mole of DEG and 78% by mole of EG were used as diol components and 100% by mole of TPA was used as the dicarboxylic acid component, the desired polyester resin Chip.

Manufacturing example 3: Center floor Production of polyester resin- (2)

Except that 17% by mole of NPG, 5% by mole of DEG, 9.8% by mole of CHDM, 68.2% by mole of EG and 100% by mole of TPA as a dicarboxylic acid component were used as the diol components, To obtain a desired polyester resin chip.

Example One

The resin chips prepared in Production Example 1 were formed as the outermost layers on both sides and the polyester resin produced in Production Example 2 was formed as a center layer. The resin chips were melt-extruded through an extruder at about 260 to 285 ° C, Extruded, and then cooled in a casting roll at about 20 DEG C to prepare an unoriented sheet. The unstretched sheet thus obtained was uniaxially or biaxially stretched to prepare a three-layer polyester film (first outermost layer: middle layer: second outermost layer thickness ratio = 1: 10: 1) having a thickness of 45 탆.

In order to reduce the thermal crystallization of the high shrinkable film, the coextruded polyester film was prepared by heating at 70 ° C.

Example 2

A three-layer polyester film was produced in the same manner as in Example 1 except that the heat fixing temperature in Example 1 was adjusted to 90 占 폚 instead of 70 占 폚.

Example 3

A three-layer polyester film was produced in the same manner as in Example 1, except that the polyester resin prepared in Preparation Example 3 was used as the center layer.

Comparative Example One

SP600 (available from SKC) produced by decreasing thermal crystallization with a copolymer of NPG and DEG as a polyester resin was melt-extruded through an extruder at about 280 DEG C and cooled in a casting roll at about 20 DEG C to obtain an unstretched sheet . Followed by the same procedure as in Example 1 to prepare a single-layer polyester film having a thickness of 45 탆.

Comparative Example 2

SP640 (available from SKC) produced by thermally crystallizing a copolymer of NPG and DEG as a polyester resin was melt-extruded through an extruder at about 280 DEG C and cooled on a casting roll at about 20 DEG C to form an unstretched sheet . Followed by the same procedure as in Example 1 to prepare a single-layer polyester film having a thickness of 45 탆.

Comparative Example 3

The PETG resin chips prepared in Production Example 1 were melt-extruded through an extruder at about 280 DEG C and cooled in a casting roll at about 20 DEG C to prepare an unoriented sheet. Followed by the same procedure as in Example 1 to prepare a single-layer polyester film having a thickness of 45 탆.

Experimental Example

Heat shrinkage measurement

The heat-shrinkable films prepared in Examples 1 to 3 and Comparative Examples 1 to 3 were heat-treated in a water bath at 90 ° C for 10 seconds and then heat-treated in the longitudinal direction (MD, machine direction) and the transverse direction (TD, ) Was measured. The results are shown in Table 1 below.

Heat shrinkage (%) = (initial length x length after heat treatment) / initial length x 100

Peel strength measurement

10 μL of tetrahydrofuran (THF) was dropped onto the surfaces of the heat-shrinkable films prepared in Examples 1 and 2 and Comparative Examples 1 to 3, covered with another heat-shrinkable film, and then subjected to uniform pressure with a roller Followed by adhesive bonding. The glued film was aged for 30 minutes and then peeled off from the seaming position with a width of 30 mm and a length of 90 mm. After each end of each film was clipped, one end was pulled at a rate of 300 mm / min using a peel tester (available from CK Corporation) to determine the maximum force (gf) at which the heat shrinkable film was separated Respectively. The peel force was measured three times for each film and the average value was calculated. The results are shown in Table 1 below.

division Peel force (gf)
(30 minutes aging after THF seaming) Heat Shrinkage (%)
(90 DEG C / 10 seconds)
(TD) One 2 3 Average Example 1 Laminated film _ High shrinkage type 1149.2 1255.7 1350.2 1251.7 75 Example 2 Laminated film _ low shrinkage type 439.4 439.7 672.9 517.3 58 Example 3 Laminated film _ High shrinkage type 1150 1201 1255 1202 70 Comparative Example 1 Single layer film _SP600 396.7 317.8 444.8 386.4 74 Comparative Example 2 Single layer film _SP640 3.2 4.5 4.2 4.0 57 Comparative Example 3 Single film _PETG alone 2305.3 2408.1 2084 2265.8 78

As shown in Table 1, it can be seen that the laminated film according to the present invention is superior in adhesiveness by tetrahydrofuran (THF) solvent to that of NPG and DEG 2 component films. Thermal crystallization of the outer layer does not proceed and excellent adhesion is exhibited.

Claims

A three-layer coextruded structure of a first outermost layer / a middle layer / a second outermost layer,
Wherein the first outermost layer and the second outermost layer each comprise a dicarboxylic acid repeating unit containing terephthalic acid (TPA) and a polyester resin comprising a diol repeating unit containing 1,4-cyclohexanedimethanol (CHDM) Lt; / RTI >
Wherein the center layer comprises a polyester resin comprising a dicarboxylic acid repeat unit comprising TPA and a diol repeat unit comprising neopentyl glycol (NPG), diethylene glycol (DEG) and ethylene glycol (EG) , Heat-shrinkable laminated film.

The method according to claim 1,
Wherein each of the first outermost layer and the second outermost layer comprises 0.5 to 100 mol% of CHDM repeating units based on the total diol repeating units.

The method according to claim 1,
Wherein the first outermost layer and the second outermost layer each comprise 80 to 100 mol% of TPA repeating units based on the total dicarboxylic acid repeating units.

The method according to claim 1,
Wherein the center layer comprises 1 to 30 mol% of NPG repeating units, 0.5 to 10 mol% of DEG repeating units, and 60 to 90 mol% of EG repeating units based on the total diol repeating units.

5. The method of claim 4,
Cyclohexanedimethanol (CHDM) repeating unit in an amount of 5 to 9.9 mol% based on the total diol repeating units.

The method according to claim 1,
Wherein the heat shrinkable laminated film has a heat shrinkage of 20% to 90% when the heat shrinkable laminated film is heat-treated at a temperature of 90 캜 for 10 seconds.

The method according to claim 1,
Wherein the heat-shrinkable laminated film has a peeling force of 100 to 2,000 gf measured after seaming with an organic solvent and aging for 30 minutes.

The method according to claim 1,
Wherein the first outermost layer, the middle layer and the second outermost layer have a thickness ratio of 1: 0.5 to 100: 1.

A packaging material or label comprising the heat-shrinkable laminated film according to any one of claims 1 to 8.