KR100654573B1 - Polyester film of superior antibiosis and heat seal - Google Patents

Abstract

The present invention is a polyester base film; And a coating layer coated with a coating composition containing 10 to 10,000 ppm of inorganic antimicrobial particles having an average particle diameter of 0.1 to 100 nm on at least one surface of the polyester base film. It relates to a manufacturing method.

The polyester film of the present invention is formed by applying an inorganic antimicrobial particle having a preferred average particle diameter and content to impart antimicrobial properties, and containing a suitable synthetic resin to impart a heat-sealing function on at least one surface of the base film. By providing a coating layer, it can be utilized for food packaging materials requiring freshness, such as vegetables, meat, general foods that require excellent antimicrobial and heat sealability.

Polyester film, antibacterial, inorganic antibacterial particle

Description

Polyester film with excellent antibacterial and heat sealability {POLYESTER FILM OF SUPERIOR ANTIBIOSIS AND HEAT SEAL}

The present invention relates to a polyester film having excellent antimicrobial activity and heat sealing property and a method for producing the same. More specifically, the present invention contains inorganic antimicrobial particles having a preferred average particle diameter and content to impart antimicrobial properties and to contain an appropriate synthetic resin. The present invention relates to a polyester film obtained by applying a heat-sealing function-coated coating composition on at least one surface of a polyester-based film and suitable for use in food packaging materials.

The polyester film is a film formed by stretching and extruding a polyester resin obtained by polycondensing one or more dicarboxylic acids and one or more diol components. Due to its excellent physical properties, it replaces other general-purpose polymer films. It is widely used for the purpose. Examples of applications include magnetic recording materials, photographic and electrical insulation, cable wrapping, capacitors, evaporation, tracing, agriculture, packaging, adhesive tape, OHP, and printer ribbons. , Has been used for magnetic cards, FPC, FRP releasing, and recently applied to high-end industrial applications, the use of the polyester film or the improvement of the properties according to the ongoing research.

Recently, as the interest in the health and hygiene environment has increased due to the improvement of living standards, the importance of hygiene is also recognized in plastic products, and consumers are demanding various plastic products having antibacterial function. In particular, since the polyester film is widely used for food packaging materials or medical films, the development of the antimicrobial polyester film has become more important.

Thus, Japanese Patent Laid-Open Nos. 2-147059 and 2-101003 attempt to impart antimicrobial properties to films using inorganic fine particles, but the present invention has been pointed out to limit antimicrobial properties by simple inorganic treatment. . In Japanese Patent Laid-Open No. 6-049274, a method of neutralizing an grafted layer of a polymer substrate formed by irradiation with an alkaline solution and adsorbing metal silver ions through an ion exchange reaction on the polymer substrate is proposed. There is a problem, and the resin mixing method of the antimicrobial composition disclosed in Japanese Unexamined Patent Publication Nos. Hei 6-87711, Hei 5-25012, Korean Patent Publication Nos. 2000-0055768 and 1998-022261 has been described. Problems are indicated in the exertion of antimicrobial activity against oxidized microorganisms. On the other hand, Japanese Patent Laid-Open No. 10-086290 discloses a film in which a surface layer having a base film and an antimicrobial laminate is laminated, but this method also needs to go through a lamination process, so the process efficiency is low.

In addition, when a polyester film is used for a packaging material, a method of laminating a polyethylene-based thermoplastic polymer film in a later step is commonly used for the heat sealing property of the packaging material due to its low heat adhesive strength. It causes another problem that lowers the antimicrobial function of the film.

Accordingly, the present inventors have endeavored to improve the physical properties for adapting the polyester film to the packaging material use, as a result, while maintaining the basic properties of the conventional polyester film, antibacterial and heat sealability required for application to the packaging material use The present invention was completed by preparing a coating composition that can be satisfied, and preparing a polyester film in which the coating composition was uniformly applied to at least one side of the polyester base film and checking the physical properties of the film.

An object of the present invention is to provide a polyester film excellent in antibacterial and heat sealability.

Another object of the present invention is to provide a method for producing the polyester film.

The present invention, in order to achieve the above object, a polyester base film; And a carrier supporting 200 to 2,900 ppm of inorganic antimicrobial particles having an average particle diameter of 0.1 to 100 nm on at least one surface of the polyester substrate film. The ethylene terephthalate unit, the ethylene isophthalate unit, and the ethylene glycol unit are selected from the group consisting of: It provides a polyester film excellent in antimicrobial and heat sealability consisting of; a coating layer formed by applying a coating composition prepared by injecting at least one copolymerized polyester resin solution dissolved in a solvent;

The inorganic antimicrobial particles are any one selected from the group consisting of silver, copper, titanium, zinc, titanium oxide and zinc oxide, wherein the inorganic antimicrobial particles are silica, zeolite, zirconium phosphate, montmorillonite, hydroxyapatite, and phosphate salts. And tripolyphosphate, magnesium aluminum silicate, calcium silicate and soluble glass.

In addition to the inorganic antimicrobial particles, the coating composition is prepared by dissolving at least one synthetic resin selected from the group consisting of ethylene terephthalate units, ethylene isophthalate units, and ethylene glycol units in a solvent. More specifically, the synthetic resin is a copolymer consisting of 30 to 95 mol% of ethylene terephthalate and 70 to 5 mol% of ethylene isophthalate.

The polyester film of this invention is a polyester film suitable for food packaging materials.

In addition, the present invention is a copolymerized polyester resin prepared by dissolving 1) a polyester-based film, 2) at least one selected from the group consisting of ethylene terephthalate units, ethylene isophthalate units and ethylene glycol units. To the solution was added a carrier carrying 200 to 2,900 ppm of inorganic antimicrobial particles having an average particle diameter of 0.1 to 100 nm to prepare a coating composition, and 3) applying the coating composition to at least one surface of the polyester base film to 0.1 It provides a method for producing the polyester film to form a coating layer having a thickness of ~ 10㎛.

Copolyester-based resin is composed of ethylene terephthalate 30 to 95 mol% and ethylene isophthalate 70 to 5 mol%, the solvent is methyl ethyl ketone, toluene, isopropyl alcohol, methanol, ethanol and ethyl acetate group Any one or any one or more selected from the mixture is used.

The inorganic antimicrobial particles are any one selected from the group consisting of silver, copper, titanium, zinc, titanium oxide and zinc oxide, wherein the inorganic antimicrobial particles are silica, zeolite, zirconium phosphate, montmorillonite, hydroxyapatite, and phosphate salts. And tripolyphosphate, magnesium aluminum silicate, calcium silicate and soluble glass.

In addition, the coating composition may be applied to at least one surface of the base film in the step of longitudinal stretching and before transverse stretching during the manufacturing process of the polyester base film, or at least one side of the base film after longitudinal stretching and transverse stretching It can be applied to.

Hereinafter, the present invention will be described in detail.

The present invention is a polyester base film; And
A carrier carrying 200 to 2,900 ppm of inorganic antimicrobial particles having an average particle diameter of 0.1 to 100 nm on at least one surface of the polyester base film; 1 selected from the group consisting of ethylene terephthalate units, ethylene isophthalate units, and ethylene glycol units It provides a polyester film excellent in antimicrobial and heat-sealing composition consisting of; coating layer formed by applying a coating composition prepared by stirring and then added to the copolymer polyester resin solution dissolved in a solvent.

The inorganic antimicrobial particles are any one selected from the group consisting of silver, copper, titanium, zinc, titanium oxide and zinc oxide, wherein the inorganic antimicrobial particles are silica, zeolite, zirconium phosphate, montmorillonite, hydroxyapatite, and phosphate salts. And tripolyphosphate, magnesium aluminum silicate, calcium silicate and soluble glass.

The average particle diameter and content of the inorganic antimicrobial particles in the coating composition of the present invention are closely related to the antimicrobial activity, process activity, and transparency of the final polyester film obtained. For example, the antimicrobial properties are continuously released at a constant rate of the antimicrobial component on the film surface to stop the microbial intake of the microorganisms or to directly destroy the cell membrane to express the antimicrobial effect, or to apply the antimicrobial agent on the film surface to physically prevent the growth of the microorganisms. Blocks and expresses antibacterial effect At this time, there is a difference in the antimicrobial efficacy according to the application concentration of the antimicrobial agent, the antimicrobial efficacy is expressed only when the concentration of the antimicrobial agent is added to the amount of 50-100 times the minimum growth inhibitory concentration value of the selected antimicrobial agent. Therefore, in order to secure the antimicrobial, transparency, activity and economics of the polyester film may vary depending on the thickness and use of the film, preferably the coating composition of the present invention is inorganic having an average particle diameter of 0.1 ~ 100nm 10 to 10,000 ppm of antimicrobial particles are contained, and more preferably 100 to 1,000 ppm of inorganic antimicrobial particles having an average particle diameter of 1 to 50 nm. More preferable content is 200-2900 ppm. In the above, when the average particle diameter of the inorganic antimicrobial particles is 0.1 nm or less and the content is 10 ppm or less, the expression of the antibacterial effect cannot be expected. Moreover, when the average particle diameter of an inorganic antimicrobial particle is 100 nm or more and content is 10,000 ppm or more, raise of processing cost will be caused. Incorporation of the inorganic antimicrobial particles may be performed at the time of the polymerization process of the synthetic resin or after the polymerization process.

The coating composition of the present invention is applied to at least one side of the polyester base film to form a coating layer, providing antimicrobial expression and heat sealability as an outer layer of the desired polyester film. Thus, the coating composition of the present invention is prepared by dissolving synthetic resin in a solvent, in addition to the inorganic antimicrobial particles, the antimicrobial activity is given from the inorganic antimicrobial particles, heat sealing is given from the selection of the preferred synthetic resin. Thus, preferred synthetic resins are co-polyester-based resins in consideration of compatibility with the base film layer and heat sealing properties of the polyester film. According to a conventional method, the copolyester resins are terephthalic acid, dimethyl terephthalic acid, isophthalic acid, naphthalene dicarboxylic acid, aliphatic dicarboxylic acid, isophthalic acid, sulfoisophthalic acid, 1,2-cyclohexane dicarboxylic acid and At least one dicarboxylic acid component selected from the group consisting of 1,3-cyclohexane dicarboxylic acid and ethylene glycol, 1,2-propylene glycol, bisphenol-A, 1,3-propanediol, 1,4-butanediol One or more diol components selected from the group consisting of neopentyl glycol, 1,6-hexanediol, 2-methylpropanediol and 1,4-cyclohexane dimethanol are prepared by condensation polymerization. In the above, the molecular weight of the synthetic resin used in the coating composition of the present invention is 1,000 to 500,000 g / mol, more preferably 10,000 to 100,000 g / mol, and during the synthetic resin polymerization, common additives such as polymer stabilizers and fillers It may contain, and as a stabilizer is used a phosphoric acid compound of phosphoric acid or phosphoric ester.

The copolyester-based resin that can be preferably used in the present invention is composed of two or more selected from the group consisting of ethylene terephthalate units, ethylene isophthalate units and ethylene glycol units.

In particular, the heat seal function is determined by the ratio of ethylene isophthalate corresponding to the ratio of ethylene terephthalate in the copolyester-based resin, preferably 30 to 95 mol% of ethylene terephthalate and ethylene iso It is to use a polyester resin copolymerized in the ratio of 70-5 mol% of phthalates. More preferably, it is a polyester resin copolymerized in the ratio of 50-90 mol% of ethylene terephthalate and 50-10 mol% of ethylene isophthalate, Most preferably, 60-85 mol% of ethylene terephthalate and 40- ethylene isophthalate It is a polyester resin copolymerized in the ratio of 15 mol%.

The coating composition of the present invention may be added to the usual additives such as heat stabilizers, antioxidants, light stabilizers, nucleating agents, flame retardants, pigments, dyes, curing agents in a range that does not impair the properties of the composition and the base film, if necessary Can be.

The polyester base film of the present invention is not particularly limited in polyester produced by a conventional method, but aromatic dicarboxylic acids such as terephthalic acid and naphthalene dicarboxylic acid, or esters thereof, and ethylene glycol, diethylene glycol, 1, What was produced by polycondensing glycols, such as 4-butanediol and neopentyl glycol, is used. More specifically, it is preferable to use one or more selected from the group consisting of polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate and copolymers thereof, and more preferably use polyethylene terephthalate.

The intrinsic viscosity (IV) of the polyethylene terephthalate used in the present invention (when measured at room temperature in a phenol / 1,1,2,2-tetrachloroethane mixed solvent) is 0.1 to 3.0 dl / g, preferably 0.6 -1.5 dl / g, More preferably, it is 0.7-1.3 dl / g. The molecular weight of the polyethylene terephthalate is 10,000 to 100,000 g / mol, more preferably 30,000 to 50,000 g / mol. Although melting | fusing point of polyethylene terephthalate is 200-265 degreeC normally, Preferably it is 220-260 degreeC, glass transition temperature is 55-125 degreeC, More preferably, it is 60-90 degreeC.

In addition, the present invention provides a method for producing the polyester film. More specifically, the manufacturing method

1) prepare a polyester base film,

2) Inorganic antimicrobial particles having an average particle diameter of 0.1 to 100 nm in a copolyester-based resin solution prepared by dissolving at least one member selected from the group consisting of ethylene terephthalate unit, ethylene isophthalate unit and ethylene glycol unit in a solvent. A coating composition was prepared by adding a carrier supporting 200 to 2,900 ppm,

3) forming a coating layer having a thickness of 0.1 ~ 10㎛ by applying the coating composition on at least one surface of the polyester base film.

In preparing the coating composition, the copolymerized polyester resin is a copolymer composed of 30 to 95 mol% of ethylene terephthalate and 70 to 5 mol% of ethylene isophthalate, and more preferably 70 to 90 mol% of ethylene terephthalate. And 30 to 10 mol% of ethylene isophthalate. At this time, the solvent is used by mixing any one or any one selected from the group consisting of methyl ethyl ketone, toluene, isopropyl alcohol, methanol, ethanol and ethyl acetate.

In addition, the inorganic antimicrobial particle is any one selected from the group consisting of silver, copper, titanium, zinc, titanium oxide and zinc oxide, the inorganic antimicrobial particles are silica, zeolite, zirconium phosphate, montmorillonite, hydroxy apatite, It is supported on any one carrier selected from the group consisting of phosphate salt, tripoly phosphate, magnesium aluminum silicate, calcium silicate and soluble glass.

In addition, the coating point of the coating composition is applied to at least one surface of the base film (in-line method) in the manufacturing process of the polyester base film, after longitudinal stretching, before transverse stretching, or longitudinal stretching and transverse stretching Then, it apply | coats to at least one surface of a base film.

Curing of the coating composition is performed by hot air during the transverse stretching process of the film when the coating composition is applied after the longitudinal stretching, and after the longitudinal stretching and the transverse stretching, the coating composition is applied after the application It is hardened by hot air dryer. In order to cure the coating composition, a process speed of 10 to 400 MPM and a curing temperature of 30 to 250 ° C is possible. More preferably, 50 to 200 MPM and a curing temperature of 50 to 240 ° C are suitable.

At this time, the coating method of the coating composition is a coating method using a roll, such as gravure roll, reverse gravure roll, coating method using a mayer bar, coating using an air knife General methods such as law can be used, and the coating layer thickness of the coating composition is 40 to 4000 µm before drying and 0.1 to 10 µm after drying. Prior to application, it is preferable to perform corona discharge treatment to increase the introduction of polar groups and surface tension on the surface of the film to favor the coating property of the composition and to improve the adhesion between the composition and the polyester resin.

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

This embodiment is intended to illustrate the present invention in more detail, and the scope of the present invention is not limited to these examples.

<Examples 1 to 6>

Polyethylene terephthalate pellets having an ultimate viscosity of 0.625dl / g containing 60 ppm of porous amorphous spherical silica particles having an average particle diameter of 3.7 µm were sufficiently dried at 160 ° C. for 7 hours using a vacuum dryer, and then melted and extruded. The die was brought into close contact with a cooling drum by electrostatic application to form an amorphous non-stretched sheet, which was then heated at 100 ° C. and stretched 3.5 times in the film advancing direction to prepare a uniaxially stretched film. Thereafter, the film was stretched 3.5 times in the vertical direction with respect to the advancing direction of the film in a tenter section at 120 ° C. and heat-treated at 240 ° C. for 4 seconds to obtain a substrate film having a thickness of 25 μm.

Separately, inorganic antimicrobial particles having an average particle diameter of 20 nm supported on silica as a carrier were added to a copolyester resin solution dissolved in a methyl ethyl ketone solvent, followed by stirring to prepare a coating composition. Thereafter, the coating composition was coated on one surface of the prepared base film to a thickness of 1 μm to form a coating layer. At this time, as shown in Table 1, except for the copolymer polyester composition ratio and the content of the inorganic antimicrobial particles used in the preparation of the coating composition, it was carried out in the same manner as above polyester excellent in antibacterial and heat sealability Films 1 to 6 were produced.

<Comparative Examples 1 and 2>

Without using the inorganic antimicrobial particles, the polyester film was prepared in the same manner as in Example except for the ratio of the copolyester composition used as shown in Table 1 when preparing the coating composition.

Experimental Example 1

1. Antimicrobial measurement

The polyester films prepared in Examples 1 to 6 and Comparative Examples 1 to 2 were cut to 100 × 100 mm and sampled to measure antimicrobial activity in the following manner. E. coli and Staphylococcus were added dropwise to the surface of the test piece, adhered to the prepared film, stored at 35 ° C. for 6 hours, and the number of test cells on the test piece was measured.

2. Heat Seal Measurement

The polyester films prepared in Examples 1 to 6 and Comparative Examples 1 and 2 were sample width 38 mm, peeling rate 10 mm / s, seal pressure 0.5 using a J & B instrument heat seal meter. Heat sealability was measured by setting at a temperature of N / mm ² , seal time 1 second and 140 ° C.

3. Haze measurement

The polyester films prepared in Examples 1 to 6 and Comparative Examples 1 and 2 were cut to a size of 100 × 100 mm and sampled. A sample of the sampled polyester film was placed vertically in a haze measuring device (AUTOMATIC DIGITAL HAZEMETER, manufactured by Nippon Densoku Co., Ltd.), and light was transmitted through a wavelength of 400 to 700 nm in a direction perpendicular to the sample placed vertically to measure the value displayed. And the haze (%) value was computed from following formula (1).

The physical property measurement results for the polyester films prepared in Examples 1 to 6 and Comparative Examples 1 and 2 are shown in Table 1 below.

Condition of Coating Composition and Measurement of Physical Properties of Prepared Polyester Film division Copolyester Composition Ratio Antimicrobial particles Evaluation results Ethyleneisophthalate (mol%) Ethylene terephthalate (mol%) Content (ppm) Heat sealability (N / mm) Number of viable bacteria (infection rate) Haze (%) Example 1 100 0 500 9 <100 (99.9%) 0.95 Example 2 40 60 500 6 <100 (99.9%) 0.95 Example 3 20 80 500 3 <100 (99.9%) 0.95 Comparative Example 1 0 100 0 0.1 1,500,000 (0.4%) 0.93 Example 4 20 80 200 6 <800 (99.8%) 0.93 Example 5 20 80 500 6 <100 (99.9%) 0.95 Example 6 20 80 1000 6 <50 (99.9%) 1.39 Comparative Example 2 20 80 0 6 1,400,000 (0.4%) 0.93

As shown in Table 1, in the case of the polyester film of Examples 1 to 3 coated with a coating composition prepared by using the same amount of inorganic antimicrobial particles and changing the copolymerized polyester composition ratio, the copolymerized polyester composition ratio As the ratio of ethylene isophthalate was increased, heat sealability was improved. In Comparative Example 1 in which the ratio of ethylene isophthalate was 0%, heat sealability was not observed. However, when the ratio of ethylene isophthalate is 40% or more, there is a problem that the surface is sticking during the unwinding process.

Of the polyester film of Examples 4 to 6 prepared by fixing the ethylene isophthalate and 20 mol% of ethylene isophthalate and 80 mol% of ethylene terephthalate and applying the coating composition prepared by changing the content of inorganic antimicrobial particles in the copolyester composition ratio. In this case, as the inorganic antimicrobial particle content was increased, the antimicrobial effect, that is, the number of viable bacteria decreased, and in Comparative Example 2 having an inorganic antimicrobial particle content of 0%, there was no antimicrobial effect. However, as the inorganic antimicrobial particle content increased, the haze was relatively increased.

As we saw above,

First, the present invention provides a polyester film suitable for food packaging materials requiring freshness, such as vegetables, meat, general foods that require excellent antibacterial and heat sealability,

Second, the present invention provides a method for producing a polyester film for food packaging material that can omit the step of laminating a polyethylene-based polymer film in the heat sealing process of the polyester film in order to use the polyester film for a conventional packaging material. Provided.

Although the present invention has been described in detail only with respect to the embodiments described, it will be apparent to those skilled in the art that various modifications and variations are possible within the technical spirit of the present invention, and such modifications and variations belong to the appended claims. .

Claims (10)

Polyester base film; And At least one surface of the polyester base film, the coating layer containing 200 to 2,900 ppm of inorganic antimicrobial particles; wherein the coating layer is one selected from the group consisting of ethylene terephthalate unit, ethylene isophthalate unit and ethylene glycol unit The coating composition prepared by adding a carrier carrying 200 to 2,900 ppm of inorganic antimicrobial particles having an average particle diameter of 0.1 to 100 nm to the copolyester-based resin solution dissolved in a solvent was prepared by stirring the polyester coating film. Polyester film excellent in antimicrobial and heat-sealing properties formed by applying to at least one side of the. The polyester film according to claim 1, wherein the inorganic antimicrobial particles are any one selected from the group consisting of silver, copper, titanium, zinc, titanium oxide and zinc oxide. The method of claim 2, wherein the carrier is any one selected from the group consisting of silica, zeolite, zirconium phosphate, montmorillonite, hydroxy apatite, phosphate salt, tripolyphosphate, magnesium aluminum silicate, calcium silicate and soluble glass. The said polyester film made into. delete The polyester film according to claim 1, wherein the copolyester-based resin is a copolymer composed of 30 to 95 mol% of ethylene terephthalate and 70 to 5 mol% of ethylene isophthalate. It has the structure of Claim 1, The polyester film for food packaging materials characterized by the above-mentioned. 1) prepare a polyester base film, 2) Inorganic antimicrobial particles having an average particle diameter of 0.1 to 100 nm in a copolyester-based resin solution prepared by dissolving at least one member selected from the group consisting of ethylene terephthalate unit, ethylene isophthalate unit and ethylene glycol unit in a solvent. After adding a carrier supporting 200 ~ 2,900 ppm and stirred to prepare a coating composition, 3) The polyester film of claim 1, wherein the coating composition is applied to at least one surface of the polyester base film and dried to form a coating layer having a thickness of 0.1 to 10 µm containing 200 to 2,900 ppm of inorganic antibacterial particles. Manufacturing method. 8. The method according to claim 7, wherein the copolymerized polyester resin is a copolymer composed of 30 to 95 mol% of ethylene terephthalate and 70 to 5 mol% of ethylene isophthalate. 8. The method of claim 7, wherein the carrier is any one selected from the group consisting of silica, zeolite, zirconium phosphate, montmorillonite, hydroxy apatite, phosphate salt, tripolyphosphate, magnesium aluminum silicate, calcium silicate and soluble glass. The manufacturing method of the said polyester film made into. The method of claim 7, wherein the coating composition is applied to at least one surface of the base film in the step of longitudinal stretching, before transverse stretching during the manufacturing process of the polyester base film, or after longitudinal stretching and transverse stretching, Method for producing the polyester film, characterized in that applied to at least one side of the film.