KR20040103639A - Biaxially oriented polyester film - Google Patents

Abstract

PURPOSE: A biaxially oriented polyester film is provided to ensure excellent transparency due to the dispersibility improvement and to exhibit the antibiotic effect. CONSTITUTION: The biaxially oriented polyester film has a haze of 10 or less and a bacteriostatic reduction rate of 80% or more with respect to at least three bacteria. Such biaxially oriented polyester film is manufactured from a resin composition comprising inorganic particles on or in which silver components are present in an amount of 0.5-5 wt%. The inorganic particles have an average particular diameter of 0.005-5 m and are contained in an amount of 0.001-5 parts by weight, based on 100 parts by weight of acid monomer in composition.

Description

Biaxially oriented polyester film excellent in transparency and antibacterial property {Biaxially oriented polyester film}

The present invention relates to a biaxially stretched polyester film, and more particularly, to a biaxially stretched polyester film prepared from a resin composition containing inorganic particles present on the surface of silver so as to satisfy both transparency and antimicrobial properties.

Recently, Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa, Salmonella, T-type phage, phage, influenza virus, HIV, rabies virus, herpes virus, yellow fever virus, Polio virus, Tabaco mosaic virus Since the pollution of living environment by harmful microorganisms, etc., is serious, causing social problems, it is becoming increasingly important to suppress the occurrence of these harmful microorganisms and maintain the stability and cleanliness of living environment.

In response to such demands, a large number of antimicrobial agents, which can be contained in fibers, paints, resin molded bodies, papers, binders, and the like, can exhibit antimicrobial properties. Among them, the inorganic antimicrobial agent is an antimicrobial agent that has attracted attention for being excellent in durability. Most inorganic antimicrobial agents have silver ions supported on inorganic compounds in various ways to exhibit antimicrobial properties.

As an antibacterial agent, silver has the features of being environmentally friendly and non-toxic, which is harmless to the human body, and has a complex function such as antibacterial, antiseptic, antifungal, deodorant and far-infrared radiation. have.

Accordingly, fungicides called silver-based inorganic antimicrobials have been put to practical use in various fields. Examples of silver-based inorganic antimicrobials include those in which silver ions or metals are supported by impregnation, adsorption, or ion exchange. Typical examples include silver ion-containing zirconium phosphate, silver ion-containing zeolites, silver-containing hydroxyapatite and the like.

On the other hand, there are various theories regarding the sterilization mechanism of silver ions. However, silver ions generate active oxygen (O ₂ ⁻ ) or hydroxy radicals (.OH), and they attack bacteria and express bactericidal properties. Alternatively, silver ions are adsorbed on the cell wall, and silver ions pass through the cell wall and bind to the protein SH group in the cytoplasm, thereby inhibiting the enzyme system in vivo.

However, there have been many problems in order to produce a polyester film using silver having excellent properties as an antimicrobial agent.

Specifically, when silver is made into the particles as described above and added during the production of the polyester film, agglomeration occurs due to the strong surface charge of the silver particles, which causes difficulty in operation and lowers the transparency. Such agglomeration can cause a problem that the silver cannot function properly while causing the surface area of the particles to drop. In addition, due to the decrease in the transparency of the resin, the haze of the produced film rises, the use that can be used is inevitably limited.

In addition, silver itself is an expensive metal, if the amount of silver support, the antibacterial effect is increased, but the price may increase as an antibacterial agent. One of the precious metals, the silver component, can not be ignored.

Conventional techniques invented to impart antimicrobial properties to polyester resins include silver compounds and zirconium when antimicrobial agents in which silver ions are substituted and bonded to calcium phosphate particles (application number 1997-075564, 1996-068489,1996-061193). And non-porous ceramics containing the compound (Application Nos. 1994-026183 and 1994-022647), and using silver containing zeolites (Application Nos. 2000-014163).

This conventional technique uses the kneading method in manufacture of a polyester resin composition. The resin composition manufactured by the kneading method has the possibility that coarse particles exist because the dispersibility of the silver-based inorganic antibacterial particles is not properly achieved. In addition, when manufacturing the film using these compositions, even if the antimicrobial properties are secured there is a problem that the transparency of the film is lowered.

Therefore, the inventors of the present invention, while using a silver inorganic antimicrobial agent, while excellent in dispersibility to ensure the transparency of the film and solve the price increase problem, while seeking a way to exhibit the antibacterial, a certain amount of silver chemically bonded to the surface Alternatively, as a result of manufacturing a polyester film containing a certain amount of inorganic particles having good dispersibility in a polyester that is present in an immersed form, dispersibility in the polyester can be ensured to ensure transparency of the film and also a problem of price increase. It has been found that the present invention can be solved to complete the present invention.

Accordingly, it is an object of the present invention to provide a biaxially stretched polyester film having antibacterial properties while ensuring transparency.

The biaxially stretched polyester film of the present invention for achieving the above object is characterized in that the haze is 10 or less and has a bacteriostatic reduction rate of at least 80% for three or more bacteria.

The present invention will be described in more detail as follows.

Of course, the polyester film of this invention contains the resin raw material used by normal polyester film manufacture.

In the polyester of the present invention, dicarboxylic acid, esters thereof, and alkylene glycol are main components, and a 2,6-naphthalate structure can be copolymerized.

The polyester of the present invention is obtained by the condensation reaction of the dicarboxylic acid component and the glycol component, and the dicarboxylic acid component may be terephthalic acid, naphthalene dicarboxylic acid and ester compounds thereof, and isophthalic acid, phthalic acid, adipic acid, Sebacic acid and ester compounds thereof may be copolymerized in small amounts. Ethylene glycol is preferable as the glycol component, but a small amount of propylene glycol, butanediol, 1,4-cyclohexanedimethanol, neopentyl glycol, and the like may be copolymerized.

In the present invention, a polyester thermal stabilizer, UV stabilizer, antioxidant, dye, antistatic agent and the like may be contained in an appropriate amount or copolymerized as necessary.

In the present invention, when the polyester is prepared by adding one or both of manganese, magnesium, and calcium compounds, the adhesiveness between the casting drum and the polymer melt may be improved during film formation by the transparency, heat resistance, and electrostatic cooling of the polymer.

However, in order to impart antimicrobial properties, silver further includes inorganic particles present on the surface, wherein the amount of silver component is preferably 0.5 to 5% by weight of the inorganic particles including silver. If the amount of silver present is less than 0.5% by weight, the desired antimicrobial activity cannot be obtained, and if more than 5% by weight, a problem arises in that the price is increased.

In order to lower the haze of the film, it is preferable to use an inorganic particle having an intrinsic refractive index of about 1.3 to 1.8, which is similar to the refractive index of the biaxially stretched polyester film. Transparency cannot be guaranteed.

Specifically, the inorganic particles are not limited as long as they belong to the range of the refractive index, but it is preferable to use inorganic particles such as silica or alumina. Silica or alumina is excellent in dispersibility in polyester.

On the other hand, the shape of the inorganic particles is not particularly limited, but the spherical shape is preferable for ensuring the dispersion in polyester.

It is preferable that the average particle diameter of an inorganic particle exists in the range of 0.005-5 micrometers. When the average particle diameter of the inorganic particles is smaller than 0.005 μm, aggregation problems occur due to an increase in the surface area of the particles, and when large, the transparency of the film is difficult to secure.

There is no restriction on the method for producing the inorganic particles on the surface of silver, but it is prepared using a method such as immersion through ion-reduction by acid, alkali immersion or electrolysis by adding silver ion aqueous solution in the state of dispersing silica. can do.

When such inorganic particles present on the surface of the silver are added during the production of the polyester film, the content thereof is preferably 0.001 to 5 parts by weight based on 100 parts by weight of the acid monomer of the polyester resin composition. If the content of the inorganic particles present on the surface of the silver is less than 0.001 part by weight with respect to 100 parts by weight of the acid monomer, the content is insignificant to impart desired antimicrobial properties. If the content is more than 5 parts by weight, the amount of particles is large, resulting in lack of transparency and increased cost. There may be a problem.

In order to obtain a composition for producing a film containing inorganic particles present on the surface, a method such as a polymerization method or a kneading method can be used. However, it is preferable to produce by the polymerization method in order to achieve the object of the present invention.

There is no restriction on the method and the order of adding the particles, but it is preferable to disperse and add to the glycol component. The timing of adding the particles is not limited at the end of the reaction, but is preferably added at the end of the transesterification or esterification reaction.

Silver-based inorganic antibacterial particles used in the present invention are anionic surfactants such as sodium dodecylbenzenesulfonate, sodium lauryl sulfate, and formalin condensate salts of naphthalenesulfonic acid, polyoxyphenol ether, and polyethylene within the range of not impairing the effects of the present invention. Nonionic surfactants such as glycol monostearate, water-soluble synthetic polymers such as polyvinyl alcohol, polyvinylpyrrolidone, polyethylene glycol, water-soluble natural polymers such as gelatin and starch, water-soluble semisynthetic polymers such as carboxymethylcellulose, or the like. There are no limitations on the treatment method before adding the particles such as surface treatment with a silane-based or titanium-based coupling agent or through normal particle dispersing, classification, and removal of coarse particles.

The polyester film thus obtained has a transparency and exhibits antimicrobial properties, and can be usefully used for packing medical devices, packing drugs, and using gold and silver.

Hereinafter, the present invention will be described in detail with reference to Examples, but the present invention is not limited by the Examples.

<Particle preparation example>

Preparation Example 1 Preparation of Particle A

10 g of spherical silica (Aerosil-OX50 manufactured by Degussa) and 90 g of distilled water having an average particle diameter of 50 nm were mixed and stirred at 1200 rpm in a homo mixer to prepare a 10% by weight aqueous slurry. Two silver bars (purity 99.99%) were immersed and 30V was applied at both ends for 6 hours. Thereafter, 90 g of ethylene glycol was added and distilled under reduced pressure at 100 ° C. to obtain silica-silver particle ethylene glycol dispersion (A).

Preparation Example 2 Preparation of Particle B

Two silver bars (purity 99.99%) were immersed in 90 g of distilled water, and a voltage of 30 V was applied at both ends for 6 hours. Then, 90 g of ethylene glycol was added and distilled under reduced pressure at 100 ° C. to obtain a silver particle ethylene glycol dispersion (B).

Preparation Example 3 Preparation of Particle C

Titanium oxide-silver particle ethylene glycol dispersion (C) was obtained by the same method as particle A except having used titanium oxide (K-1080 by Kronos, Inc.) whose average particle diameter is 300 nm instead of spherical silica.

Preparation Example 4 Preparation of Particle D

Alumina-silver particle ethylene glycol dispersion (D) was obtained by the same method as particle A, except that alumina (Degus Co., Ltd. Aluminum Oxide-C) having an average particle diameter of 13 nm was used instead of spherical silica.

The average particle diameter of the particles obtained through Preparation Examples 1 to 4 was measured by LS-13320 of Beckmann Coulter, USA, and 50 g of the prepared ethylene glycol dispersion was placed in an electric furnace at 600 ° C. for 12 hours to measure the residual weight. It was measured by the method. The silver content present on the surface of the inorganic particles was measured by using the SPS1200AR, an ICP analyzer manufactured by Seiko, Japan.

The results are shown in Table 1 below.

Average particle size (nm) Inorganic particles Refractive index Solid content (% by weight) Silver content in solids (% by weight) Dispersion A 80 Silica 1.61 10 2 Dispersion B 77 - - One 99 Dispersion C 297 Titanium oxide 2.55 10 2 Dispersion D 74 Alumina 1.70 10 2

<Production of Polyester Film>

Example 1

100 parts by weight of dimethyl terephthalate, 64 parts by weight of ethylene glycol, 0.8 parts by weight of magnesium acetate, and 0.3 parts by weight of antimony oxide were placed in a reaction tube, and a transesterification reaction was carried out while raising the temperature from 140 ° C to 230 ° C. Thereafter, 0.5 parts by weight of trimethyl phosphate was added, and 20 minutes later, 1 part by weight of particle A was added so that the solid content in the reaction system was 0.1 part by weight. Decompression was performed while gradually raising the temperature from 230 ° C to 280 ° C for 1 hour. Then, the polymerization reaction was carried out at 280 ° C. under high vacuum for 2 hours, and then discharged and cut to obtain a polyester composition.

After drying the composition under high vacuum at 160 ° C. for 5 hours, an amorphous sheet was prepared by electrostatically applied cooling method, stretched 3.5 times in the longitudinal direction and the width direction, and heat-treated at 220 ° C. to obtain a polyester film having a thickness of 15 μm. .

Example 2

A film having a thickness of 15 µm was obtained in the same manner as in Example 1, except that Particle D was used instead of Particle A.

Comparative Example 1

A polyester film having a thickness of 15.5 μm was obtained in the same manner as in Example 1, except that the particles were not added.

Comparative Example 2

A polyester film having a thickness of 14.5 μm was obtained in the same manner as in Example 1, except that 10 parts by weight of particle B was used instead of particle A so that the solid content of the reaction system was 0.1 parts by weight.

Comparative Example 3

A polyester film having a thickness of 14.8 μm was obtained in the same manner as in Example 1, except that 1 part by weight of particle C was added instead of particle A so that the solid content was 0.1 part by weight in the reaction system.

The haze and bacteriostatic reduction rate were measured about the polyester film obtained by the said Examples 1-2 and Comparative Examples 1-3, and it was judged that the thing of haze 10 or more or bacteriostatic reduction rate 80% or less was unusable.

Here, the haze was measured by the method of ASTM D-1003 using a 1001DP machine from Denshoku Kogyo Co., Ltd., and antimicrobial activity against three types of bacteria, specifically Staphylococcus aureus ATCC 6538, Escherichia coli ATCC 25922, Escherichia coli ATCC 43895 The bacteriostatic reduction rate was measured by the method of film adhesion method (FC-TN-20) -2001. Here, only three kinds of bacteria were measured, but silver showed antimicrobial activity against general bacteria known to have antibacterial activity.

The measurement results are shown in Table 2 below.

Participants Haze Bacteriostatic reduction rate (%) Judgment ATCC 6538 ATCC 25922 ATCC 43895 Example 1 Silver-silica 5.0 99.9 99.8 99.7 Available Example 2 Silver-alumina 4.4 99.8 99.9 99.9 Available Comparative Example 1 - 1.0 18.5 20.2 19.3 can not be used Comparative Example 2 silver 1.2 19.0 21.2 18.3 can not be used Comparative Example 3 Silver-titanium oxide 25.0 99.8 99.7 98.8 can not be used

From the results in Table 2, according to the present invention, the polyester films (Examples 1 and 2) prepared by including the silica particles on the surface of silver or the alumina particles on the surface of the silver were prepared for all three types of bacteria. It can be seen that the haze is maintained at 5.0 while showing a bacteriostatic reduction rate of more than%. However, when no particles are included (Comparative Example 1), the transparency is excellent but does not show any antimicrobial properties, and when only silver is added (Comparative Example 2), since aggregation is severe in the reaction system and silver exists only at the local part, Silver was not found and this resulted in transparency but not antimicrobial activity.

In the case where the inorganic particles carrying silver were titanium oxide (Comparative Example 3), the antimicrobial properties were excellent, but the refractive index was high, resulting in a drop in transparency.

As described in detail above, in the case of preparing a polyester film using the inorganic particles having good dispersibility in the polyester resin composition according to the present invention and treating the silver to exist on the surface thereof, it is excellent in dispersibility and transparency As a result, it is possible to obtain an antimicrobial effect even with a small amount of silver, thereby reducing the price increase.

Claims (4)

A biaxially stretched polyester film having a haze of 10 or less and having a bacteriostatic reduction rate of at least 80% for three or more kinds of bacteria. The biaxially oriented drawing according to claim 1, wherein the silver component is prepared from a resin composition containing, on the surface or inside, an inorganic particle having an average particle size of 0.005 to 5 µm at 0.001 to 5 parts by weight based on 100 parts by weight of the acid monomer. Polyester film. The biaxially stretched polyester film according to claim 2, wherein the silver component is present at 0.5 to 5% by weight in the inorganic particles containing silver. The biaxially stretched polyester film according to claim 2, wherein the inorganic particles have an intrinsic refractive index of 1.3 to 1.8.