KR20000040096A - Polyester film for hologram and manufacturing method thereof - Google Patents

Abstract

PURPOSE: A method for manufacturing a polyester film for hologram is provided to obtain multi-layer polyester film of an excellent soft embossing characteristic by improving a hologram characteristic and heat resistance by embossing without fusion of a coating layer with an original plate. CONSTITUTION: A method for manufacturing a polyester film for hologram includes the steps of forming a first high molecular resin having a limit viscosity of 0.5-.07dl/g by ploycondensation of dicarboxyl acid containing more than 80weight% of terephtal acid and alkylenglycol containing more than 80weight% of ethylene glycol, forming a second high molecular resin having a melting temperature of 190-220°C by polycondensation of dicarboxyl acid containing terephtal acid and isophtal acid with a ratio of 90:10-72:25weight% and alkylene glycol containing more than 80weight% of ethylene glycol, forming a longitudinally stretched sheet having a crystallization energy of 15J/g by longitudinally stretching after forming a non stretched stacked sheet by air pressing the first and second high molecular resins, and traversely stretching and performing a thermal processing after coating a water soluble acryl resin solution having a molecular weight of 10,000-300,000 on the second high molecular resin layer of the longitudinally stretched sheet to be a thickness of 500angstrom or less when drying.

Description

The polyester film for a hologram and the method of producing the same

The present invention relates to a polyester film for soft embossing used in the production of a film for holograms and a method for manufacturing the same, and more particularly to laminating resin layers having different surface densities through coextrusion and high temperature multi-stretching and coating processes. The present invention relates to a hologram polyester film having excellent processability and excellent heat resistance, and capable of processing a wide hologram at high speed without fusion to an excellent mechanical property and an embossing roll.

In recent years, as the industrial structure becomes very complicated and the necessity of the material to satisfy the diversified demand increases, there is a growing interest in the polymer material having excellent moldability and light weight as a suitable material that can satisfy this demand. .

In particular, various polymer resins having advantages in different physical properties can be made into a final film having excellent physical properties by mutually compensating for the shortcomings of individual resins through processing methods such as copolymerization and coextrusion. Development is active.

Among them, polyester resins containing polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate, and the like, in particular, polyethylene terephthalate (hereinafter referred to as PET) are physically and chemically stable, have high mechanical strength, heat resistance, durability, Due to its excellent chemical resistance and electrical insulation, it is widely used in various industrial products such as medical, electromagnetic, packaging, and photographic film.

In particular, in the holographic film that is widely used for eye catching, polyester film has been used a lot for stickers or security because of its excellent mechanical properties. The field is gradually expanding.

However, the existing polyester film is embossed to make a film for hologram only at high temperature and high pressure, so there is a problem that is not appropriate for mass production for packaging purposes.

In order to improve such a problem, embossing is possible under relatively low temperature and low pressure conditions, and thus, a wide range of embossing can be performed at high speed. Thus, a material such as polypropylene coextrusion film or PVC film, which can exhibit high productivity, has been developed and used. As the material is poor in heat resistance, there is a problem that the film breaks due to adhesion with the embossed disc at a certain temperature or higher during processing.In order to prevent this, the embossing depth is reduced during high temperature post-processing in order to prevent low temperature molding. Because of this, it was impossible to increase hologram processability and heat resistance at the same time. That is, due to the basic characteristics of the polymer, when hologram embossing is possible at a low temperature, heat resistance is inevitably degraded, and when heat resistance is increased, hologram processability is inferior.

The present invention is to solve the problems of the prior art as described above, the co-extrusion of each resin layer containing a heterogeneous polyester resin as a main component, the surface density is different through a high temperature multi-stage stretching and coating process It is an object of the present invention to provide a holographic polyester film and a method of manufacturing the same that can improve the mechanical properties and hologram processability by laminating a resin layer and at the same time solve a problem of adhesion with a holographic disc through a coating process.

The present invention for achieving the above object is composed of at least one surface of the first polymer resin layer and the first polymer resin layer made of copolyester resin containing at least 80% by weight of the main repeating unit ethylene terephthalate 75 to 90% by weight of the main repeating unit is ethylene terephthalate and 10 to 25% by weight of the second polymer resin layer made of copolyester of ethylene isophthalate and one surface of the second polymer resin layer It provides a polyester film for hologram, characterized in that the water-soluble acrylic resin having a molecular weight of 10,000 to 300,000 consists of a third polymer layer coated with a thickness of 500 kPa or less and is at least uniaxially stretched.

In another aspect, the present invention is a process for producing a first polymer resin having a polyviscosity of 0.5 to 0.7 dl / g by polycondensation of dicarboxylic acid containing at least 80% by weight of terephthalic acid and alkylene glycol containing at least 80% by weight of ethylene glycol; And polycondensing dicarboxylic acid containing terephthalic acid and isophthalic acid at a ratio of 90:10 to 75: 25% by weight and alkylene glycol containing 80% by weight or more of ethylene glycol to produce a second polymer resin, and Coextruding the first polymer resin and the second polymer resin to prepare an unstretched laminated sheet, and longitudinally stretching the same; and drying a water-soluble aqueous acrylic resin solution having a molecular weight of 10,000 to 300,000 on the surface of the second polymer resin layer. Fabrication of a holographic polyester film, characterized in that it comprises a step of coating the thickness of the solid to 500Å or less and then transverse stretching and heat treatment Provide a method.

The polyester of the first polymer resin layer preferably has an intrinsic viscosity of 0.5 to 0.7 dl / g and an ethylene terephthalate content in the main repeating unit of 80% by weight or more. The copolyester of the second polymer resin layer preferably has a melting temperature in the range of 190 to 220 ° C. and 15 to 25% by weight of the main repeating unit is ethylene isophthalate.

The thickness of the second polymer resin layer is 10 to 40%, more preferably 15 to 30% with respect to the total polymer film thickness. The third polymer resin layer should be coated with a thickness of 500 kPa or less, and it is preferable to harden the composition of the resin by attaching a curing agent to the water-soluble acrylic resin.

In the method of manufacturing a multilayer polyester film for holographic embossing, in order to improve the embossing characteristics, the second polymer resin layer is softened by suppressing the crystallization of the second polymer resin as much as possible, and the first polymer resin layer serving as the support layer has a stable crystallization structure. desirable.

In order to achieve the above object, the present invention extends the melt-extruded unstretched sheet through a multi-stage longitudinal stretcher, but stretches at a high temperature so that the crystallization energy of the longitudinal stretched sheet is 15 J / g or more, then coats the acrylic resin and performs transverse stretching. Provided is a method for producing a biaxially oriented polyester film. In addition, the longitudinally oriented sheet, which has undergone less orientation determination, is laterally stretched and then quenched to an atmospheric temperature after heat treatment for 3 seconds or more within the melting temperature range of the second polymer resin and the melting temperature range of the first polymer resin layer in the heat treatment process. The film of which the density of a 1st polymer resin layer is 1.39 or more, the surface density of a 2nd polymer resin layer is 1.36 or less, and the thickness of a 3rd resin layer is 500 kPa or less is produced.

Hereinafter, the manufacturing method of the polymer film of the present invention and the principle of the present invention will be described in detail. First, dicarboxylic acid containing at least 80% by weight of terephthalic acid, alkylene glycol containing at least 80% by weight of ethylene glycol, and a dispersant, an electrostatic agent, a crystallization promoter, an antiblocking agent, and an inorganic lubricant are added as conventional catalysts and additives. Combined to prepare a first polymer resin having an intrinsic viscosity of 0.5 to 0.7 dl / g.

At this time, an aromatic dicarboxylic acid is used as the dicarboxylic acid, and specific examples thereof include dimethyl terephthalic acid, terephthalic acid, dimethylisophthalic acid, diphenyldicarboxylic acid, diphenylcarboxylic acid, diphenyl ether dicarboxylic acid, anstazene dicarboxylic acid, α, β-bis ( 2-chlorophenol c) ethane-4,4-dicarboxylic acid, etc. are mentioned, Among these, dimethyl terephthalic acid and terephthalic acid are preferable. In addition, the alkylene glycol may be used ethylene glycol, trimethylene glycol, pentamethylene glycol, hexamethylene glycol or hexylene glycol.

Subsequently, an acid component containing terephthalic acid and isophthalic acid in a ratio of 90:10 to 75: 25% by weight and an alkylene glycol containing 80% by weight or more of ethylene glycol are mixed and a catalyst and an additive are prepared as in the case of preparing the first polymer resin. Addition and polycondensation to prepare a copolyester of the second polymer resin.

In forming the copolyester with the second polymer resin, the content of the repeating unit of ethylene isophthalate in the main repeating unit is preferably 10 to 25% by weight, if the content of ethylene isophthalate is less than 10% by weight, the second While the crystallization of the polymer resin proceeds rapidly, the embossing property is lowered, whereas if the content exceeds 25% by weight, the melting temperature of the resin is lowered, and it is deteriorated in the feed block during coextrusion with PET, which is used as a substrate, to produce a film. It may cause process trouble such as breaking.

The first polymer resin and the second polymer resin are melted and coextruded to form a layer of the first polymer resin and the second polymer resin prepared as described above, thereby obtaining an unstretched sheet having two layers.

In the coextrusion process, the thickness of the second polymer resin layer is preferably adjusted to be 15 to 30% of the total thickness of the unstretched sheet. Subsequently, the polyester unstretched sheet was preheated again on the primary preheat roll, the cooling roll, and the secondary preheat roll using a conventional three stage longitudinal drawing apparatus, and then subjected to three stage longitudinal stretching on the stretching roll to prepare the longitudinal stretch sheet. do.

By performing three or more steps of high temperature multistage longitudinal stretching, the crystallization energy of the longitudinally stretched sheet is 15 J / g or more, and the longitudinally stretched sheet is coated with a water-soluble acrylic resin.

The crystallization energy of 15 J / g or more means that the energy generated during the crystallization process is above a certain level, and implies that the orientation determination of the coextruded longitudinally stretched sheet is below a certain level. In addition, orientation determination is less advanced, resulting in less breakage and non-uniform stretching in subsequent stretching processes.

The acrylic resin used in the present invention is a monomer used in the emulsion polymerization, methyl acrylate, ethyl acrylate, n-acrylate, ethyl acrylate, iso-butyl methacrylate, 2-hydroxyethyl methacrylate, hydroxy Propyl acrylate, acrylamide, glycidyl methacrylate. In particular, the average molecular weight of the acrylic solid is preferably about 10,000 to 300,000, and more preferably about 20000 to 200000. If the average molecular weight is 10000 or less, the embossing characteristic is too hard, and if the molecular weight is 300000 or more, the frictional force is increased, and the slidability is inferior. The glass transition temperature of the acrylic resin used is 30 to 100 ℃, the concentration of the acrylic resin is contained 2 to 10 parts by weight, it is preferable to apply so that a solid of 0.01 to 0.5g / m ² is present on the film surface, 0.01g If it is / m ² or less, hologram embossing is not performed. The longitudinally stretched sheet is stretched 2.5 to 4 times in the lateral direction, and thermal crystallization occurs through heat treatment at 220 ° C. or higher for 3 seconds or more, and the first water layer has different rates of thermal crystallization between the first resin layer and the second resin layer. Crystallization proceeds rapidly, and the second resin layer has an effect that the orientation crystals are released while the film surface is heated to a temperature above the melting point. In this way, the first polymer resin layer and the second polymer resin layer have different densities, while maintaining excellent mechanical properties, while the second resin layer does not undergo crystallization and has a low density, and a soft material is formed, thereby improving embossing characteristics. . In addition, since the third polymer resin layer is hardened and the material is hardened and coated, the third polymer resin layer solves the problem that the second polymer resin layer sticks to the original plate during embossing, and at the same time, exhibits a property of increasing heat resistance during hologram processing. In this manner, the polyester film for hologram embossing of the present invention is obtained.

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

Example 1

After terephthalic acid and ethylene glycol were mixed in a 1: 2 equivalent ratio, a polycondensation catalyst and a thermal stabilizer were added to the mixture to carry out a polycondensation reaction, and then, at a nitrogen atmosphere, about 2 hours at 120 ° C. and about 3 hours at 170 ° C. Drying made a polyester resin as a first polymer resin having an intrinsic viscosity of 0.62 dl / g.

Terephthalic acid and isophthalic acid were mixed with an acid component composed of a weight ratio of 85:15 and ethylene glycol in a 1: 2 equivalent ratio, and then a polycondensation catalyst and a heat stabilizer were added to the mixture, followed by a polycondensation reaction to give an intrinsic viscosity of 0.66. A solidified copolyester resin (melting temperature: 200 ° C.) of dl / g was prepared. The resin was dried for about 200 minutes at 80 ° C., about 120 minutes at 120 ° C., and about 180 minutes at 182 ° C. under a nitrogen atmosphere to prepare a second polymer resin.

The first polymer resin layer having an intrinsic viscosity of 0.62 dl / g and the second polymer resin layer having a thickness of 0.66 dl / g using a die-die equipped with two extruders and a feed block adjusted to have a thickness ratio of 80:20 The resin is melted and extruded, and then melt-extruded at a sheet forming rate of 60 m / min to be in close contact with a 30 ° C cooling roll to obtain an unoriented laminated sheet.

The unstretched sheet was stretched 3.5 times at a total longitudinal draw ratio in the longitudinal direction using a high temperature multistage stretching apparatus to produce a uniaxially stretched film. On the second polymer resin layer of this coextruded film, a coating liquid obtained by dissolving 5 parts by weight of styrene methacrylate in an aqueous solution composed of 15 parts by weight of isopropyl alcohol and 75 parts by weight of water was applied by a reverse roll method and dried to obtain 0.05 g / m ² . The application rate and application were determined so that the solid active ingredient was present. The longitudinally stretched sheet coated with the coating solution was stretched 3.5 times in the transverse direction and then heat-treated at 220 ° C. for 3 seconds to obtain a biaxially stretched multilayer polyester film having a thickness of 20 μm and a strength of 19.4 kgf / mm ² . At this time, the thickness of the multilayer film was measured using a scanning electron microscope (SEM), the thickness of the first polymer resin layer was 16μm, the thickness of the second polymer resin layer was 4μm, the thickness of the coating layer was 0.02μm (200 (). . Various evaluation methods performed during the preparation of the prepared film were measured by the method defined in the following Experimental Example, in the case of the polymer film prepared in this Example, the density of the second polymer resin layer is 1.351 and the first polymer resin layer The density of was 1.392. After embossing the prepared film to the temperature and depth as shown in Table 1 below, the results of adhesion, embossing depth and heat resistance test results with the embossing disc are shown in Table 1 below.

Experimental Example

Melting Temperature

Melting temperature of the resin was measured using a differential thermal analyzer (DSC-7, Perkin Elmer Co., Ltd.), the temperature was raised to 300 ℃ to melt the sample and then quenched and then measured again while raising the temperature at a rate of 20 ℃ / min .

Adhesion to Embossing Disc

-No adhesion

+: Bonded

+ +: Strongly bonded

+ + +: Film is torn when falling off the original

Heat resistance

The embossed film was placed in a temperature controlled oven for 60 seconds, taken out, and the thickness before and after the heat treatment at the hologram embossing depth was measured and evaluated by AFM.

Film Thickness

The thickness of each layer of the polymer film was measured using a scanning microscope (SEM).

Crystallization Energy

The crystallization energy of the longitudinally stretched sheet was measured at a temperature increase rate of 20 ° C./min through a differential calorimeter (DSC, Perkin Elmer).

Film density

The laminated film was separated and measured using a density gradient tube according to ASTM D 1505.

Example 2

A film was manufactured in the same manner as in Example 1, except that the thickness of the third polymer resin layer was changed to 0.05 μm by changing the coating amount. The adhesion, embossing depth, and heat resistance test results of the film thus prepared with the embossed disc are shown in Table 2 below.

Comparative Example 1

In Example 1, a two-layer film made of a second polymer resin layer was prepared without forming a third polymer resin layer, and its properties were compared. The adhesion, embossing depth and heat resistance test results of the film thus prepared with the embossed disc are shown in Table 3 below.

Comparative Example 2

A film was prepared and evaluated in the same manner as in Example 1, except that the thickness of the third polymer resin layer in Example 1 was 0.10 μm. The adhesion, embossing depth, and heat resistance test results of the film thus prepared with the embossed disc are shown in Table 4 below.

Comparative Example 3

A film was prepared and evaluated in the same manner as in Example 1 except that the first polymer resin layer and the second polymer resin layer were the same as the first polymer resin layer. The adhesion, embossing depth and heat resistance test results of the film thus prepared with the embossed disc are shown in Table 5 below.

Comparative Example 4

A film was prepared and evaluated in the same manner as in Example 1, except that the heat setting temperature was 180 ° C. in Example 1. The adhesion, embossing depth, and heat resistance test results of the film thus prepared with the embossed disc are shown in Table 6 below.

Embossing Temperature (℃) Adhesiveness with Embossed Disc Embossing Depth Heat resistance test (embossing depth after heat treatment) 120 ℃ 140 ℃ 160 ℃ 180 ℃ 100 － 1200 1000 800 400 400 110 － 1200 1100 1000 600 600 120 － 1300 1200 1100 800 800 130 － 1500 1400 1300 1000 900 140 － 2000 2000 2000 2000 2000 150 － 2000 2000 2000 2000 2000 160 － 2000 2000 2000 2000 2000 170 － 2000 2000 2000 2000 2000 180 － 2000 2000 2000 2000 2000 190 － 2000 2000 2000 2000 2000 200 － 2000 2000 2000 2000 2000

Embossing Temperature (℃) Adhesiveness with Embossed Disc Embossing Depth Heat resistance test (embossing depth after heat treatment) 120 ℃ 140 ℃ 160 ℃ 180 ℃ 100 － 1000 800 700 600 500 110 － 1000 900 800 700 600 120 － 1200 1100 900 800 700 130 － 1300 1200 1000 900 800 140 － 1400 1300 1200 1100 1000 150 － 1500 1500 1500 1500 1500 160 － 1500 1500 1500 1500 1500 170 － 1500 1500 1500 1500 1500 180 － 1500 1500 1500 1500 1500 190 － 1500 1500 1500 1500 1500 200 － 1500 1500 1500 1500 1500

Embossing Temperature (℃) Adhesiveness with Embossed Disc Embossing Depth Heat resistance test (embossing depth after heat treatment) 120 ℃ 140 ℃ 160 ℃ 180 ℃ 100 + 1300 1000 800 400 200 110 + 1600 1300 1100 600 300 120 + 2000 1800 1300 800 400 130 + 2000 1800 1300 800 400 140 +++ Not measurable Not measurable Not measurable Not measurable Not measurable 150 +++ Not measurable Not measurable Not measurable Not measurable Not measurable 160 +++ Not measurable Not measurable Not measurable Not measurable Not measurable 170 +++ Not measurable Not measurable Not measurable Not measurable Not measurable 180 +++ Not measurable Not measurable Not measurable Not measurable Not measurable 190 +++ Not measurable Not measurable Not measurable Not measurable Not measurable 200 +++ Not measurable Not measurable Not measurable Not measurable Not measurable

Embossing Temperature (℃) Adhesiveness with Embossed Disc Embossing Depth Heat resistance test (embossing depth after heat treatment) 120 ℃ 140 ℃ 160 ℃ 180 ℃ 100 － 100 0 0 0 0 110 － 100 0 0 0 0 120 － 100 0 0 0 0 130 － 100 0 0 0 0 140 － 100 0 0 0 0 150 － 100 0 0 0 0 160 － 100 0 0 0 0 170 － 100 0 0 0 0 180 － 100 0 0 0 0 190 － 100 0 0 0 0 200 － 100 0 0 0 0

Embossing Temperature (℃) Adhesiveness with Embossed Disc Embossing Depth Heat resistance test (embossing depth after heat treatment) 120 ℃ 140 ℃ 160 ℃ 180 ℃ 100 － 200 0 0 0 0 110 － 200 0 0 0 0 120 － 200 0 0 0 0 130 － 200 0 0 0 0 140 － 200 0 0 0 0 150 － 200 0 0 0 0 160 － 200 0 0 0 0 170 － 200 0 0 0 0 180 － 200 0 0 0 0 190 － 200 0 0 0 0 200 + 200 0 0 0 0

Embossing Temperature (℃) Adhesiveness with Embossed Disc Embossing Depth Heat resistance test (embossing depth after heat treatment) 120 ℃ 140 ℃ 160 ℃ 180 ℃ 100 － 200 0 0 0 0 110 － 200 0 0 0 0 120 － 200 0 0 0 0 130 － 200 0 0 0 0 140 － 200 0 0 0 0 150 － 200 0 0 0 0 160 － 200 0 0 0 0 170 － 200 0 0 0 0 180 － 200 0 0 0 0 190 － 200 0 0 0 0 200 + 200 0 0 0 0

As can be seen from the results of Table 1 to Table 2 in the embodiment of the present invention almost no adhesion with the embossed disc in the entire temperature range did not cause any breakage of the film during embossing, especially in Example 1 In the case of the film embossed at a temperature of 130 ° C. or higher and 150 ° C. or higher, the embossing depth can be maintained even at a high temperature heat treatment, and thus the hologram shape is maintained in a circular shape, thereby exhibiting excellent properties in terms of heat resistance and workability.

On the other hand, in the case of Comparative Example 1, when the embossing temperature is 140 ℃ or more, the adhesion with the original is very large, the film breaks seriously, and it is impossible to measure the embossing depth after the initial embossing depth and the heat resistance test.

In addition, in the case of Comparative Example 2 in which the acrylic resin coating layer was too thick, the coating layer formed a hard layer so that the embossing was poor, and thus the hologram shape could not be maintained at all after the heat resistance test, and in Comparative Example 3, the second polymer resin layer was present. Since no problems were found in terms of adhesion with the embossed disc, the embossing was also very poor, and thus the hologram shape was not maintained at all after the heat resistance test.

In case of Comparative Example 4 in which the heat setting temperature was set to 180 ° C., no problems were found in terms of adhesion to the embossed disc, but the embossing was also very poor, and thus the hologram shape was not maintained after the heat resistance test. This is because the density of the second polymer resin layer is 1.38, so that the second polymer resin layer is crystallized and the overall physical properties are similar to those of the first polymer resin layer.

As can be seen from the above, according to the present invention, in thinning a water-soluble acrylic coating on a laminated film composed of PET and PET copolymers, by limiting the density of the multilayer film and the thickness of the coating layer, embossing without fusion with the original plate, the hologram characteristics It is possible to produce a multilayer polyester film for soft embossing which is excellent and at the same time excellent in heat resistance.

Claims (6)

80 wt% or more of the main repeating unit is composed of at least one side of the first polymer resin layer made of a copolyester polyester resin containing ethylene terephthalate and the first polymer resin layer and 75 to 90 wt% of the main repeating unit Is an ethylene terephthalate and 10 to 25% by weight of the second polymer resin layer made of copolyester of ethylene isophthalate and one surface of the second polymer resin layer, the water-soluble acrylic resin having an average molecular weight of 10,000 to 300,000 The polyester film for hologram which consists of a 3rd polymer layer apply | coated to the thickness of 500 micrometers or less, and is uniaxially stretched at least. The polyester film for hologram according to claim 1, wherein the copolymer polyester resin of the first polymer resin layer has an intrinsic viscosity of 0.5 to 0.7 dl / gr. The holographic polyester film of claim 1 or 2, wherein the copolyester resin of the second polymer resin layer has a melting temperature of 190 to 220 ° C. The polyester film for hologram according to claim 3, wherein the thickness of the second polymer resin layer is 10 to 40% of the total film thickness. Polycondensing dicarboxylic acid containing 80% by weight or more of terephthalic acid and alkylene glycol containing 80% or more by weight of ethylene glycol to prepare a first polymer resin having an ultimate viscosity of 0.5 to 0.7 dl / g, and terephthalic acid and iso Preparing a second polymer resin having a melting temperature of 190 to 220 ° C. by polymerizing a dicarboxylic acid containing phthalic acid at a ratio of 90:10 to 75: 25% by weight and an alkylene glycol containing 80% by weight or more of ethylene glycol. A step of coextruding the first polymer resin and the second polymer resin to produce an unstretched laminated sheet, followed by longitudinal stretching to produce a longitudinal stretch sheet having a crystallization energy of 15 J / g, and the longitudinal stretch sheet After coating a water-soluble acrylic resin aqueous solution having a molecular weight of 10,000 to 300,000 on the surface of the second polymer resin layer to dry the thickness of the solids to 500Å or less, and then transverse stretching and heat treatment Method of producing a hologram polyester film which is characterized in that it comprises the information. The method of claim 5, wherein the temperature during the heat treatment is 220 ° C or more.