JP4274200B2 - Deposition polyester film - Google Patents

Description

The present invention relates to a vapor-deposited polyester film, and more particularly, to a vapor-deposited polyester film using a specific substrate polyester film as a substrate in a vapor-deposited film formed by forming a metal or metal oxide thin film .

  Vapor-deposited polyester film can be selected from metal and / or metal oxide to be vapor-deposited, gas barrier properties, moisture impermeability, visible / ultraviolet light shielding properties, heat ray reflectivity, conductivity, transparent conductivity, magnetic recording Since characteristics such as property can be changed in various ways, they are used for various purposes. For example, it is used for packaging materials, decorative materials, window glass shielding materials, gold / silver thread materials, capacitor materials, display materials, wiring board materials, magnetic recording materials, and the like. This vapor-deposited polyester film has a problem that the vapor-deposited film is partially peeled during the film processing step or in contact with moisture, and the characteristics as the vapor-deposited film, for example, the gas barrier property is lowered.

  Conventionally, in order to prevent the gas barrier property from being lowered, the anchor coating agent (coating agent) such as various polyurethanes, various polyesters, or a mixture of polyurethane and polyester is used between the base film of the vapor-deposited polyester film and the vapor-deposited layer. A method of providing a coating layer (undercoat layer) is known (see, for example, Patent Document 1). Furthermore, in order to improve water-resistant adhesion and solvent resistance, an anchor coating agent containing a special polyurethane, polyester and epoxy compound has been proposed (see, for example, Patent Document 2).

JP-A-2-50837 JP-A-4-176858

  However, any of the above-mentioned vapor-deposited polyester films has insufficient water resistance (hot water resistance) and solvent resistance at high temperatures. Therefore, when used for food packaging, printing is performed after boiling treatment or with solvent-based ink. Later gas barrier properties are not always sufficient. In particular, a vapor-deposited polyester film that reuses polyester film waste has a drawback that the gas barrier property is remarkably lowered. Further, as the use of the vapor-deposited polyester film is expanded, there is a demand for a vapor-deposited polyester film having stronger adhesiveness and highly reliable gas barrier properties.

  Further, the coating layer with the anchor coating agent may be provided after the film is formed, but an in-line coating method provided in the film forming process is also possible. For example, when the film is a biaxially stretched film, the anchor coating agent is applied to the uniaxially stretched film, stretched in the transverse direction in a dry or undried state, and then subjected to heat treatment. Since drying can be performed simultaneously, a great merit can be expected in terms of manufacturing cost. However, an appropriate base polyester film for vapor deposition provided with a coating layer by this in-line coating method is not known, and a vapor deposition film obtained from the base polyester film is a vapor deposition obtained by an ordinary method. There is a problem that the solvent resistance and hot water resistance are insufficient as compared with the film, and the gas barrier properties after printing or after hot water treatment such as boiling and retort are remarkably lowered.

  In view of the above situation, the present inventors have conducted extensive studies to solve the above problems, and as a result, based on the surface roughness of the coating layer coated in-line as the polyester film of the base material. According to the vapor deposition film used as the material film, it has been found that a good vapor deposition film excellent in adhesion, solvent resistance, gas barrier properties after the boil treatment, and the like can be provided, and the present invention has been achieved.

That is, the present invention is a vapor-deposited polyester film formed by forming a metal and / or metal oxide thin film on the surface of a base polyester film, wherein the base polyester film is water-soluble on at least one side of the polyester film. The surface roughness Rms of the coating layer formed by applying an anchor coating agent containing a water-soluble or water-dispersible acrylic resin and an aqueous polyurethane resin and then stretching in at least one direction is 0.7 to 6 nm. and, the surface roughness Rms excluding the low frequency components of the surface irregularities are der Ru base polyester film below 0.5 nm, moreover, the oxygen permeability of the deposited polyester film ^{1 (cc / m 2 / day} ) It is related with the vapor deposition polyester film characterized by the following .

Vapor deposition polyester film of the present invention, in terms of excellent gas barrier properties of water vapor and oxygen, and excellent in such as gas barrier property after solvent resistance and hot water treatment, and can be manufactured at low cost. Such a vapor-deposited polyester film can be used by being laminated with other plastic films, paper, etc., or can be used with a cured film layer on a thin film, which requires blocking of various gases such as water vapor and oxygen. It can be applied to packaging applications, etc. in order to prevent the deterioration of products, packaging of foods, industrial products and pharmaceuticals.

  Hereinafter, the present invention will be described in detail. The polyester in the present invention is represented by polyethylene terephthalate in which 80 mol% or more of the structural unit is ethylene terephthalate, polyethylene naphthalate in which 80 mol% or more of the structural unit is ethylene naphthalate, etc. Not. Examples of copolymer components other than the above components include diol components such as diethylene glycol, propylene glycol, neopentyl glycol, and cyclohexane dimethanol, isophthalic acid, adipic acid, azelaic acid, sebacic acid, and dicarboxylic esters thereof. An acid component or the like can be used. Moreover, the polyester in this invention may use the reproduction | regeneration polyester processed into the chip form of the scrap film generated in the manufacturing process of a polyester film product from a viewpoint of resource saving.

  The polyester in the present invention may contain additive particles that form projections on the film surface, precipitated particles, and other catalyst residues in a range that is commonly used by those skilled in the art depending on the application. Further, as additives other than the above-described protrusion forming agent, an antistatic agent, a stabilizer, a lubricant, a crosslinking agent, an antiblocking agent, an antioxidant, a colorant, a light blocking agent, an ultraviolet absorber, etc. May be contained.

  A film using such a polyester raw material can be produced by a conventionally known general method. For example, an unstretched film that is substantially amorphous and not oriented can be produced by melting a raw material resin with an extruder, extruding it with an annular die or a T die, and rapidly cooling it. The unstretched film is subjected to a film flow (vertical axis) direction or a film by a conventionally known general method such as uniaxial stretching, tenter sequential biaxial stretching, tenter simultaneous biaxial stretching, and tubular simultaneous biaxial stretching. The film stretched in at least one direction can be finally produced by stretching in the flow direction and the direction perpendicular to the flow direction (horizontal axis).

  The thickness of the polyester film is usually selected from the range of 5 to 500 μm, preferably 10 to 200 μm, depending on the application, such as mechanical strength, flexibility and transparency as the base material of the deposited film. Further, the width and length of the film are not particularly limited and can be appropriately selected according to the intended use. In addition, the polyester film can be subjected to surface treatment by a conventionally known method such as corona discharge treatment, flame treatment, plasma treatment, glow discharge treatment, chemical treatment, etc. before forming the coating layer.

  In the present invention, the anchor coating agent is applied to at least one surface of the polyester film in an unstretched or uniaxially stretched stage in the film manufacturing process. For example, in the case of a biaxially stretched film having a coating layer, an anchor coat agent is preferably applied to a film uniaxially stretched in the machine direction (film flow direction), and stretched in the transverse direction in a dry or undried state, If necessary, heat treatment is performed.

  As a specific coating method, known methods such as an air doctor coater, a rod coater, a reverse roll coater, a gravure coater, and a kiss coater can be employed. According to the anchor coating treatment, the adhesion between the thin film and the film can be generally improved, but as a result, good gas barrier properties, adhesion, solvent resistance, and hot water resistance are easily exhibited. The thickness of the anchor coating agent is selected in the range of usually 0.005 to 5 μm, preferably 0.01 to 1 μm, in accordance with the surface unevenness of the polyester film to be used. Usually, when the thickness is less than 0.005 μm, uneven coating occurs. On the other hand, when the thickness exceeds 5 μm, uneven thickness of the coating layer tends to occur and the slipperiness of the film tends to decrease.

The anchor coating agent, but using the anchor coating agent containing water-soluble or water-dispersible acrylic resin and an aqueous polyurethane resin, Po Riesuteru type resin, Oh Kisazorin group containing resins, ethylene vinyl alcohol resins, vinyl-modified Resins, epoxy resins, modified styrene resins, modified silicone resins, alkyl titanates, and the like can be used alone or in combination of two or more .

  The acrylic resin is a resin mainly composed of alkyl acrylate and / or alkyl methacrylate. Specifically, the content ratio of the alkyl acrylate and / or alkyl methacrylate component is usually 40 to 95 mol%. A water-soluble or water-dispersible resin of an emulsifier-free type in which the content of the vinyl monomer component that can be polymerized and has a functional group is usually 5 to 60 mol% is desirable. Examples of the functional group in the vinyl monomer include a carboxyl group, an acid anhydride group, a sulfonic acid group or a salt thereof, an amide group or an alkylolated amide group, an amino group (including a substituted amino group), Examples thereof include an alkylolated amino group or a salt thereof, a hydroxyl group, and an epoxy group, and a carboxyl group, an acid anhydride group, an epoxy group, and the like are particularly preferable.

  The polyester resin is preferably a water-soluble or water-dispersible resin that does not contain a low molecular weight hydrophilic dispersant or the like. Such a polyester resin preferably contains a carboxyl group or a salt thereof (hereinafter simply abbreviated as a carboxyl group) in order to increase the affinity with an aqueous medium. The polyurethane resin is preferably a water-soluble or water-dispersible resin produced by reacting a polyhydroxy compound and a polyisocyanate compound according to a conventional method, and preferably contains a carboxyl group.

  The oxazoline group-containing resin is preferably water-soluble or water obtained by polymerizing an addition-polymerizable oxazoline described in JP-B-6-39548 and at least one other monomer as required. Dispersible polymer. Examples of this addition polymerizable oxazoline include 2-vinyl-2-oxazoline, 2-vinyl-4-methyl-2-oxazoline, 2-vinyl-5-methyl-2-oxazoline, 2-isopropenyl-2-oxazoline. 2-isopropenyl-4-methyl-2-oxazoline, 2-isopropenyl-5-ethyl-2-oxazoline and the like, and two or more of these may be used in combination. In addition, there is no limitation as long as it is a monomer copolymerizable with addition polymerizable oxazoline. For example, methacrylic acid esters such as methyl methacrylate, butyl methacrylate, and 2-ethylhexyl methacrylate, methacrylic acid, itaconic acid, maleic acid, etc. Unsaturated carboxylic acids, unsaturated nitriles such as methacrylonitrile, unsaturated amides such as methacrylamide and N-methylol methacrylamide, vinyl esters such as vinyl acetate and vinyl propionate, methyl vinyl ether, ethyl vinyl ether, etc. Vinyl ethers, α-olefins such as ethylene and propylene, halogen-containing α and β-unsaturated monomers such as vinyl chloride, vinylidene chloride and vinyl fluoride, α and β-unsaturated such as styrene and α-methylstyrene Aromatic monomers and the like, and these are 2 It may be used in combination or more.

  Furthermore, when using the above resin compound, when epoxy compounds, such as glycidyl acrylate and glycidyl methacrylate, are used together, it can bridge | crosslink to side chains, such as a carboxyl group, in a resin compound, and can improve adhesiveness with a vapor deposition film. The above anchor coating agent is usually diluted with water or an organic solvent and applied to the surface of the polyester film as a solution or dispersion. In addition, in the coating solution at this time, a conventionally known crosslinking agent such as a silane coupling agent, inorganic fine particles, antifoaming agent, foaming agent, coating property improving agent, thickener, antistatic agent, lubricant, Polymer particles, antioxidants, ultraviolet absorbers, dyes, pigments and the like can also be added.

  In the present invention, as described above, the anchor coating agent is applied to at least one surface of the polyester film to form a coating layer, and then the surface roughness Rms (A) of the coating layer after being stretched in at least one direction is The roughness Rms (B) excluding the low frequency component of the surface irregularities is 0.7 to 6 nm, preferably 0.5 nm or less, preferably (A) is 0.8 to 5 nm, and (B) is It is 0.4 nm or less.

  In the case of the in-line coating method, since the stretching is performed after the anchor coating is applied, it is easy to take a surface form in which the coating layer is divided. Therefore, when the surface roughness (A) is less than 0.7 nm, the surface unevenness is too fine (for example, the horizontal interval between the unevenness is about 0.1 μm, the unevenness height is about 3 nm), and the adhesion of the thin film particles. This is not preferable because the density of particle deposition becomes weak. Further, when the surface roughness (A) exceeds 6 nm, a problem due to uneven coating tends to occur, which is not preferable.

  The roughness (B) means a large waviness in the measurement area, that is, a roughness of minute unevenness present on the large waviness excluding a low frequency component of the surface unevenness. This roughness (B) has an optimum range of Rms 0.5 nm or less from the relationship with the size of the deposited particles. Because the vapor deposition particles are deposited more densely and without gaps, and the gas barrier property of the vapor deposition film is improved, the minute irregularities present on the large undulations (low frequency components of the irregularities) It is presumed that it affects the way of the deposition of. Therefore, it is considered that when the roughness (B) exceeds Rms 0.5 nm, the thin film particles are not densely deposited due to the unevenness, and the adhesion between the thin film and the base film is weakened.

  In order to obtain the base film for the vapor deposition film of the present invention having such surface roughness characteristics, the production conditions such as the application conditions of the anchor coating agent in the production method and the stretching conditions after application are greatly affected. Also, the type and composition of the anchor coating agent can have a great influence. The surface roughness of the coating layer surface here is a roughness Rms (root mean square) obtained by roughness analysis of an AFM topography image measured by a commercially available atomic force microscope (hereinafter referred to as “AFM”). Square root roughness). In the measurement of the AFM topography image, a measurement mode corresponding to the resonance mode is employed. For example, the measurement may be performed in a tapping mode when an apparatus manufactured by Digital Instruments is used, and in a dynamic force mode when an apparatus manufactured by Seiko Instruments Inc. is used. Further, the above topographic image refers to an image representing the uneven shape of the surface of an object.

  The surface roughness (A) was obtained by using, for example, an SPI 3700 manufactured by Seiko Instruments Inc., measuring with a measurement area of 1 × 1 μm square, performing an automatic tilt correction process with software attached to the AFM apparatus, and then obtained as described above. Similarly, the topographic image is subjected to a three-dimensional roughness analysis with attached software to obtain an Rms value. However, the measurement is performed by avoiding a portion where the filler contained in the film appears on the surface shape so that the error does not increase.

  The surface roughness (B) is measured by the surface roughness (A) and subjected to the fast topographic image on the same topographic image as that subjected to the automatic tilt correction process, and blocks 25 / μm or less in both the x and y directions. The low frequency component of the surface unevenness is removed as the frequency. Furthermore, the inverse Fourier transform is performed to reproduce the topography image after removing the low frequency components. Since the reproduced image has a distortion in the peripheral portion, a three-dimensional roughness analysis is performed by selecting a central 800 nm square excluding the peripheral portion, and an Rms value is obtained.

  The polyester film subjected to the anchor coating treatment as described above is used as a base film for a vapor deposition film. In the present invention, examples of the metal and / or metal oxide to be deposited include metals such as aluminum, silicon, magnesium, palladium, zinc, tin, nickel, silver, copper, gold, indium, stainless steel, chromium, and titanium, Aluminum oxide, zinc oxide, antimony oxide, indium oxide, calcium oxide, cadmium oxide, silver oxide, gold oxide, chromium oxide, silicon oxide, cobalt oxide, zirconium oxide, tin oxide, titanium oxide, iron oxide, copper oxide, oxide Metal oxides such as nickel, platinum oxide, palladium oxide, bismuth oxide, magnesium oxide, manganese oxide, molybdenum oxide, vanadium oxide, and barium oxide can be mentioned, but silicon oxide and aluminum oxide have a high oxygen gas barrier property, water vapor Combines barrier properties and transparency, and is industrially inexpensive A particularly preferred because there. Such silicon oxide and aluminum oxide may be used alone or as a mixture. The deposition method of these metals and / or metal oxides is generally vacuum deposition, but may be a method such as ion plating, sputtering, or CVD. The vapor deposition film is formed on the surface of the coating layer. The thickness of the deposited film is appropriately selected depending on the final use of the deposited film. In addition, a resin protective layer may be provided on the vapor deposition surface in order to provide adhesion after vapor deposition, in particular, water-resistant adhesion and scratch resistance.

  Hereinafter, the contents and effects of the present invention will be described in more detail with reference to examples. However, the present invention is not limited to the following examples unless it exceeds the gist. In addition, the method of the measurement and evaluation of the base polyester film and vapor deposition polyester film in a following example is as follows.

<Roughness Rms (A) of coating layer surface of base polyester film>
Using a scanning probe microscope SPI3700 manufactured by Seiko Instruments as an atomic force microscope (AFM), the surface of the base polyester film of the thin film gas barrier film in Examples and Comparative Examples is measured in a dynamic force mode with a measurement area of 1 × 1 μm square. The AFM topography image measured under the conditions of scanning speed 1 Hz, xy direction 512 × 256 division, cantilever SI-DF-20 (Si, f = 126 kHz, C = 16 N / m) was subjected to an automatic tilt correction process, and then 3 Dimensional roughness analysis was performed to determine Rms (nm). At this time, the cantilever used for the measurement was one that was not worn or soiled. Moreover, the location to measure was made into the location which does not have the protrusion and hollow by a lubricant, a filler, etc. in a film.

<Roughness Rms (B) excluding low-frequency components on the surface irregularities of the coating layer of the base polyester film>
The topography image measured by the above <surface roughness of the substrate film> and subjected to the automatic tilt correction process is subjected to a fast Fourier transform, and the low frequency component of the surface irregularities with a cutoff frequency of 25 / μm or less in both the x and y directions. And the inverse Fourier transform was performed to reproduce the topography image after removing the low frequency components. The reproduced image was subjected to a three-dimensional roughness analysis by selecting an approximately 800 nm square at the central portion excluding the peripheral portion to obtain Rms (nm).

<Thin film thickness>
The cross section of the vapor deposition film obtained by the Example and the comparative example was observed with the transmission electron microscope (Hitachi Ltd. H-600 type | mold), and the thickness of the thin film was measured.

<Oxygen transmission rate of vapor-deposited film (cc / m ² / day)>
Based on ASTM D-3985, an oxygen transmission rate measurement device (OX-TRAN100, manufactured by Modern Control Co., Ltd.) was used, measured under conditions of 25 ° C. and relative humidity of 95%, and judged according to the following criteria. 1 or less; ○ (good), 2 or more; × (bad)

<Solvent resistance test of deposited film>
A NewLP super white gravure ink made by Toyo Ink was printed on the thin film surface to a thickness of 2 μm, dried at 80 ° C. for 1 minute, and after 1 day at 23 ° C. and 50% relative humidity, the oxygen transmission rate was measured.

<Heat resistant water test of deposited film>
It was boiled at 90 ° C. for 30 minutes, lightly wiped off, and after one day at 23 ° C. and 50% relative humidity, the oxygen transmission rate was measured.

Example 1:
Polyethylene terephthalate with an intrinsic viscosity of 0.62 dl / g is extruded from the die of an extruder at a temperature of 280 to 300 ° C., cast into a cooling drum while using an electrostatic adhesion method, and an amorphous polyester sheet having a thickness of about 150 μm is formed. Obtained. After the above sheet was stretched 3.5 times in the longitudinal direction at 95 ° C., an aqueous medium coating solution containing 20, 70, and 10 parts by weight of the following A, C, and E was applied to one side of the film, The film was stretched 3.5 times in the transverse direction at 110 ° C. and heat-treated at 230 ° C. to obtain a biaxially stretched polyester film having a coating layer thickness of 0.1 μm and a base polyester film thickness of 12 μm.

  On the coated surface of this film, a roll-up vacuum deposition apparatus is used, and SiO (manufactured by Sumitomo Sitix Co., Ltd.) is evaporated as a deposition material by a high-frequency heating method, and the film thickness is 25 nm under the condition of a pressure of 8 × 10 −5 Torr. A silicon oxide vapor deposition film was formed to obtain a vapor deposition film on which a silicon oxide thin film was formed. The physical property results of this deposited film are shown in Table-1.

Example 2:
A biaxially stretched polyester film was obtained in the same manner as in Example 1 except that the coating liquid was changed to an aqueous medium coating liquid containing 35, 30, 25, and 10 parts by weight of the following A, B, C, and D, respectively. A vapor deposition film was obtained. The physical property results of this deposited film are shown in Table-1.

Example 3:
A biaxially stretched polyester film was obtained in the same manner as in Example 1 except that the coating liquid was changed to an aqueous medium coating liquid containing 40, 40, 10 and 10 parts by weight of the following A, C, D and E, respectively. A vapor deposition film was obtained. The physical property results of this deposited film are shown in Table-1.

Comparative Example 1:
A biaxially stretched polyester film was obtained in the same manner as in Example 1 except that the coating liquid was changed to an aqueous medium coating liquid containing 70, 20, and 10 parts by weight of C, D, and E, respectively. Obtained. The physical property results of this deposited film are shown in Table-1.

Comparative Example 2:
A biaxially stretched polyester film was obtained in the same manner as in Example 1 except that the coating liquid was changed to an aqueous medium coating liquid containing 70 and 30 parts by weight of C and E, respectively, to obtain a vapor-deposited film. The physical property results of this deposited film are shown in Table-1.

Resin A: Aqueous acrylic resin A mixture of 40 parts by weight of ethyl acrylate, 30 parts by weight of methyl methacrylate, 20 parts by weight of methacrylic acid, and 10 parts by weight of glycidyl methacrylate was solution polymerized in ethyl alcohol, and water was added after polymerization. Heat to remove ethyl alcohol. The pH was adjusted to 7.5 with aqueous ammonia to obtain a coating solution of an aqueous acrylic resin (non-emulsifier type).

Resin B: EPOCROS WS-500 manufactured by Nippon Shokubai Co., Ltd. was used as a water-soluble polymer solution containing oxazoline groups (water: 1-methoxy-2-isopropanol = 1: 2).

Resin C: Aqueous polyurethane-based resin aqueous paint First, a polyester polyol comprising 664 parts by weight of terephthalic acid, 631 parts by weight of isophthalic acid, 472 parts by weight of 1,4-butanediol, and 447 parts by weight of neopentyl glycol was obtained. Next, 321 parts by weight of adipic acid and 268 parts by weight of dimethylolpropionic acid were added to the obtained polyester polyol to obtain a pendant carboxyl group-containing polyester polyol A. Further, 160 parts by weight of hexamethylene diisocyanate was added to 1880 parts by weight of the above polyester polyol A to obtain an aqueous polyurethane resin aqueous coating material.

Resin D: Polyester WR-961 manufactured by Nippon Synthetic Chemical Industry was used as a water-dispersed polyester having a carboxyl group.

Compound E: Epoxy compound triethylene glycol diglycidyl ether was used.

Claims (1)

A vapor-deposited polyester film formed by forming a thin film made of a metal and / or metal oxide on the surface of a coating layer of a base polyester film, wherein the base polyester film is water-soluble or water-dispersible on at least one side of the polyester film . The surface roughness Rms of the coating layer formed by applying an anchor coating agent containing an acrylic resin and an aqueous polyurethane resin and then stretching in at least one direction is 0.7 to 6 nm, and surface irregularities wherein the low-frequency component obtained by removing surface roughness Rms is der Ru base polyester film below 0.5 nm, moreover, the oxygen permeability of the deposited polyester film is ^{1 (cc / m 2 / day} ) or less Vapor-deposited polyester film (however, the above Rms and oxygen permeability mean values measured by the following method) .

<Roughness Rms of surface of coated layer of base polyester film>
As the atomic force microscope (AFM), a scanning probe microscope SPI3700 manufactured by Seiko Instruments Inc. is used, and the surface of the base polyester film is measured in a dynamic force mode with a measurement area of 1 × 1 μm square, a scanning speed of 1 Hz, and an x-y direction of 512 × 256 divisions. For AFM topography images measured under the conditions of cantilever SI-DF-20 (Si, f = 126 kHz, C = 16 N / m), automatic tilt correction processing is performed, then three-dimensional roughness analysis is performed, and Rms (nm) is calculated. Asked. At this time, the cantilever used for the measurement was one that was not worn or soiled. Moreover, the location to measure was made into the location which does not have the protrusion and hollow by a lubricant, a filler, etc. in a film.
<Roughness Rms excluding low-frequency components of the coating layer surface irregularities of the base polyester film>
The topography image measured by the above <surface roughness of the substrate film> and subjected to the automatic tilt correction process is subjected to a fast Fourier transform, and the low frequency component of the surface irregularities with a cutoff frequency of 25 / μm or less in both the x and y directions. And the inverse Fourier transform was performed to reproduce the topography image after removing the low frequency components. The reproduced image was subjected to a three-dimensional roughness analysis by selecting a central portion of about 800 nm square excluding the peripheral portion, and Rms (nm) was obtained.

<Oxygen transmission rate of vapor deposition film (cc / m ² / day)>
Based on ASTM D-3985, an oxygen transmission rate measuring device (Modern Control, OX-TRAN100) was used, and measurement was performed under conditions of 25 ° C. and relative humidity of 95%.