Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B27/00—Layered products comprising a layer of synthetic resin
  • B32B27/28—Layered products comprising a layer of synthetic resin comprising synthetic resins not wholly covered by any one of the sub-groups B32B27/30 - B32B27/42

Definitions

• the present invention relates to a gas barrier laminate film used in the packaging fields of food, medicine, industrial products, etc., or a gas barrier laminate film used inside electronic components, and a manufacturing method thereof. More specifically, the present invention relates to a gas barrier laminate film that is a laminate film having a base film, an inorganic thin film layer, and a coating layer, and that can exhibit good water vapor barrier properties and transparency, and a manufacturing method thereof.
• Packaging materials used for food, medicine, etc. are required to have the ability to block gases such as oxygen and water vapor in order to protect the contents, i.e., gas barrier properties.
• gas barrier materials used for electronic devices and display applications such as quantum dots and organic electroluminescence, are required to have higher gas barrier properties than packaging materials for food, medicine, etc.
• a higher degree of transparency may also be required for display applications.
• gas barrier laminate films are known that have a gas barrier layer with gas barrier function on the surface of a plastic base film.
• gas barrier layers are those in which an inorganic thin film made of metal or metal oxide is formed using a vacuum deposition method, or a coating layer made of an organic resin or inorganic compound is formed using a wet coating method.
• Patent Document 1 discloses a gas barrier laminate film having a vapor deposition layer made of an inorganic compound on the surface of a plastic substrate film, and a gas barrier coating layer formed by applying a coating agent made of a composition containing a water-soluble polymer and an aqueous solution containing silicon alkoxide and its hydrolysate, and then heating and drying.
• a coating agent made of a composition containing a water-soluble polymer and an aqueous solution containing silicon alkoxide and its hydrolysate
• Patent Document 2 discloses a gas barrier laminate film having a silicon oxide film formed by plasma CVD on the surface of a plastic substrate film, the gas barrier laminate being obtained by polycondensing a composition containing silicon alkoxide, a silane coupling agent, and a water-soluble polymer by a sol-gel method.
• plasma CVD is suitable for achieving high gas barrier properties, there are problems such as the long time required for film formation and the high manufacturing costs.
• Patent Document 3 a gas barrier laminate film with excellent gas barrier properties is provided by enhancing the heat treatment conditions for coating layer formation to promote the sol-gel reaction and form a dense coating layer. While enhancing the heat treatment conditions can increase the density of the coating layer, there are concerns that this may lead to a decrease in transparency and an increase in wrinkles for the base film. In addition, there remains the issue that prolonged heat treatment significantly reduces productivity.
• Patent Document 3 The inventors' investigations have revealed that the gas barrier laminate described in Patent Document 3 has room for improvement in water vapor barrier properties while maintaining excellent transparency.
• the present invention was made against the background of such conventional technology, and provides a gas barrier laminate having excellent transparency and water vapor barrier properties in a gas barrier laminate film having a coating layer made of a water-soluble polymer and silicon alkoxide, and a method for producing the same.
• the inventors discovered that by controlling the progress of the reaction of the inorganic components in the coating layer, it is possible to improve the water vapor barrier performance and produce a highly transparent film, thus completing the present invention.
• the present invention comprises the following: (1) A gas barrier laminate film having an inorganic thin film layer and a coating layer made of a silicon alkoxide and a water-soluble polymer on at least one surface of a polyester base film, characterized in that in an infrared absorption spectrum of the coating layer of the gas barrier laminate film measured by a total reflection measurement method, the ratio (P2/P1) of a peak intensity (P1) having an absorption maximum in the region of 1070 ⁇ 30 cm -1 to a peak intensity (P2) at 1220 cm -1 is within a range of 0.25 or less.
• the water-soluble polymer contains a polyvinyl alcohol-based resin.
• a method for producing the gas barrier laminate film according to any one of (1) to (5) comprising the steps of: A step of forming an inorganic thin film layer on at least one surface of a polyester substrate film; The method includes a step of forming a coating layer by applying a coating liquid containing silicon alkoxide, a hydrolysate of silicon alkoxide, and a water-soluble polymer onto the inorganic thin film layer, A method for producing a gas barrier laminate film, comprising storing the silicon alkoxide and the silicon alkoxide hydrolysate at 0 to 20° C. for 1 to 15 days before mixing the silicon alkoxide and the silicon alkoxide hydrolysate with the water-soluble polymer.
• the present invention it is possible to improve the water vapor barrier properties of a laminate film having a coating layer made of a water-soluble polymer and a silicon alkoxide, and to provide a gas barrier laminate film with excellent water vapor barrier properties.
• the gas barrier laminate film of the present invention comprises a polyester base layer and a coating layer, and in an infrared absorption spectrum measured by a total reflection measurement method, the ratio (P2/P1) of a peak intensity (P1) having an absorption maximum in the region of 1070 ⁇ 30 cm -1 to a peak intensity (P2) at 1220 cm -1 is within a range of 0.25 or less.
• the inventors discovered that the ratio of infrared absorption spectra (P2/P1) in the coating layer correlates with water vapor barrier properties, and further discovered a method for improving this measure.
• the infrared absorption spectrum ratio (P2/P1) is preferably 0.25 or less, more preferably 0.245 or less, and even more preferably 0.24 or less.
• P2 is thought to be an index representing 4-membered ring silica that leads to defects in amorphous silica
• P1 is thought to be an index representing 6-membered ring silica, which is the main structure of amorphous silica.
• the smaller the P2/P1 ratio the denser the silica network with fewer defects, and the fewer holes through which water molecules can pass, which is thought to improve water vapor barrier properties. Furthermore, improved transparency can be expected as the molecules are aligned.
• the P2/P1 ratio of the gas barrier laminate film according to this embodiment can be controlled, for example, by appropriately adjusting the conditions for forming the coating layer.
• the P2/P1 ratio can be controlled by the processing conditions of the silicon alkoxide.
• P2/P1 can be reduced by leaving silicon alkoxides and their hydrolysates at low temperatures for long periods of time.
• the gas barrier laminate film of the present invention has an inorganic thin film layer and a coating layer provided on at least one side of a polyester base film.
• the polyester base film will be described, followed by an explanation of the inorganic thin film layer, the coating layer and other layers.
• the polyester substrate film used in the present invention may be, for example, a film obtained by melt-extruding a polyester and, if necessary, stretching the polyester in the longitudinal direction and/or the transverse direction, cooling, and heat setting.
• a film obtained by melt-extruding a polyester and, if necessary, stretching the polyester in the longitudinal direction and/or the transverse direction, cooling, and heat setting.
• the polyester polyethylene terephthalate, polybutylene terephthalate, polyethylene-2,6-naphthalate, etc. are preferred in terms of heat resistance, dimensional stability, and transparency, and polyethylene terephthalate and copolymers obtained by copolymerizing polyethylene terephthalate with other components are particularly preferred.
• this polyester base film may contain known additives, such as ultraviolet absorbers, antistatic agents, plasticizers, lubricants, and colorants.
• the film may be subjected to corona discharge treatment, glow discharge treatment, and other surface treatments, as long as the purpose of the present invention is not impaired. It may also be subjected to known anchor coat treatment, printing, and decoration.
• the polyester substrate film can be of any thickness depending on the desired purpose and application, such as mechanical strength and transparency, and the thickness is preferably in the range of 1 ⁇ m or more and 300 ⁇ m or less, and more preferably in the range of 10 ⁇ m or more and 60 ⁇ m or less.
• the transparency of the base film there are no particular limitations on the transparency of the base film, but if it is to be used as a packaging material that requires transparency, it is desirable for it to have a light transmittance of 50% or more.
• Inorganic thin film layer Inorganic compounds used in the inorganic thin film layer include metals such as aluminum, silicon, titanium, zinc, zirconium, magnesium, tin, copper, and iron, as well as oxides and nitrides of these metals, and mixtures thereof may also be used. From the viewpoint of gas barrier properties, inorganic oxides such as silicon oxide and aluminum oxide are preferred. In particular, complex oxides of silicon oxide and aluminum oxide are preferred from the viewpoint of achieving both flexibility and denseness of the thin film layer.
• the mixing ratio of silicon oxide and aluminum oxide is preferably in the range of 20 to 70 mass% Al in terms of the mass ratio of the metal content. If the Al concentration is less than 20 mass%, the water vapor barrier property may be reduced. On the other hand, if it exceeds 70 mass%, the inorganic thin film layer tends to become hard, and the film may be destroyed during secondary processing such as printing or lamination, resulting in a decrease in gas barrier property.
• silicon oxide here refers to various silicon oxides such as SiO and SiO2, or mixtures thereof
• aluminum oxide refers to various aluminum oxides such as AlO and Al2O3 , or mixtures thereof.
• the method for forming the inorganic thin film layer is not particularly limited, and any known deposition method may be used as appropriate, such as physical deposition methods such as vacuum deposition, sputtering, and ion blading, and chemical deposition methods such as plasma vapor phase growth, and the inorganic thin film layer may be a single layer or a laminate of two or more layers.
• the inorganic thin film layer usually has a thickness of 1 to 100 nm, preferably 5 to 50 nm. If the inorganic thin film layer is less than 1 nm thick, it may be difficult to obtain satisfactory gas barrier properties. On the other hand, if the inorganic thin film layer is made too thick, exceeding 100 nm, the corresponding improvement in gas barrier properties will not be obtained, and it may be disadvantageous in terms of flex resistance and manufacturing costs.
• the gas barrier laminate film of the present invention may have an adhesive layer between the substrate layer and the inorganic thin film layer.
• the resin composition used for the adhesive layer may be a resin such as a urethane-based, polyester-based, acrylic-based, titanium-based, isocyanate-based, imine-based, or polybutadiene-based resin to which a curing agent such as an epoxy-based, isocyanate-based, or melamine-based curing agent has been added. It is preferable that the resin composition used for these adhesive layers contains a silane coupling agent having at least one type of organic functional group. Examples of the organic functional group include an alkoxy group, an amino group, an epoxy group, and an isocyanate group. The addition of the silane coupling agent further improves adhesion.
• the resin compositions used in the adhesion layer it is preferable to use a mixture of a resin containing an oxazoline group with an acrylic resin and a urethane resin.
• the oxazoline group has a high affinity with inorganic thin films and can react with oxygen-deficient parts and metal hydroxide parts of inorganic oxides generated during the formation of the inorganic thin film layer, and shows strong adhesion to the inorganic thin film layer.
• unreacted oxazoline groups present in the adhesion layer can react with carboxylic acid terminals generated by hydrolysis of the polyester base film layer to form crosslinks.
• the method for forming the adhesion layer is not particularly limited, and known methods such as a coating method can be used.
• a coating method can be used.
• offline coating method and in-line coating method are preferred.
• the in-line coating method is more preferred because it allows the adhesion layer to be applied simultaneously in the process of manufacturing the base film layer, leading to reduced man-hours and reduced costs.
• Solvents that can be used when using the coating method include, for example, aromatic solvents such as benzene and toluene; alcohol solvents such as methanol, ethanol, and isopropanol; ketone solvents such as acetone and methyl ethyl ketone; ester solvents such as ethyl acetate and butyl acetate; and polyhydric alcohol derivatives such as ethylene glycol monomethyl ether.
• aromatic solvents such as benzene and toluene
• alcohol solvents such as methanol, ethanol, and isopropanol
• ketone solvents such as acetone and methyl ethyl ketone
• ester solvents such as ethyl acetate and butyl acetate
• polyhydric alcohol derivatives such as ethylene glycol monomethyl ether.
• the thickness of the adhesion layer is usually 0.005 to 5 ⁇ m, preferably 0.01 to 1 ⁇ m. If it is less than 0.005 ⁇ m, it may be difficult to obtain a uniform coating film and adhesion. On the other hand, even if it is made too thick exceeding 5 ⁇ m, the corresponding improvement in adhesion cannot be obtained, and it may be disadvantageous in terms of production costs.
• the coating amount of the adhesion layer (after drying) is preferably about 0.01 to 1 g/ m2 .
• the coating layer used in the present invention is made of a mixture containing silicon alkoxide and its hydrolysate and a water-soluble polymer, and is formed by accelerating a crosslinking reaction by application of heat.
• the silicon alkoxide may be an alkoxysilane, such as tetraethoxysilane, tetramethoxysilane, tetrapropoxysilane, methyltriethoxysilane, methyltrimethoxysilane, etc.
• Tetraethoxysilane is particularly preferred because it is relatively stable in aqueous solvents.
• the hydrolysate of silicon alkoxide may be one in which at least one of the alkoxy groups of silicon alkoxide has become a hydroxyl group.
• the hydrolysate of silicon alkoxide can be prepared by known methods. For example, it can be prepared by adding an aqueous solution of an acid such as hydrochloric acid to silicon alkoxide and carrying out a hydrolysis reaction. Silicon alkoxide and its hydrolysate will have hydroxyl groups through the hydrolysis reaction, and a dense and strong polymer coating can be formed by dehydrating and condensing these hydroxyl groups together.
• the P2/P1 ratio can be reduced by allowing the obtained silicon alkoxide hydrolysate to stand at low temperature for a long period of time. Although a dehydration condensation reaction also occurs simultaneously in silicon alkoxide and its hydrolysate, it is believed that the reaction can be made gentle by keeping the solution environment at a low temperature, and a dense silica network can be selectively generated. This creates a favorable condition for improving water vapor barrier properties.
• the standing temperature is preferably 0 to 20°C, more preferably 0 to 10°C, and particularly preferably 0 to 5°C.
• the standing time is preferably 1 to 15 days, and more preferably 3 to 12 days.
• the transparency of the gas barrier laminate film can be improved by leaving the hydrolyzate of silicon alkoxide at low temperature for a long period of time. It is believed that the silica network becomes dense, resulting in a uniform coating layer and suppressing light scattering.
• the haze which is an index of transparency, is preferably 3.0 or less, and more preferably 2.5 or less.
• the water-soluble polymer may be any polymer that has a hydroxyl group in the molecule, such as polyvinyl alcohol resin, starch, cellulose, etc.
• polyvinyl alcohol resin is preferred. Since polyvinyl alcohol resin contains many hydroxyl groups in the molecule, it can form hydrogen bonds with the hydroxyl groups of silicon alkoxide, resulting in a coating layer with superior barrier properties.
• polyvinyl alcohol resins are generally obtained by saponifying polyvinyl acetate, and include so-called partially saponified polyvinyl alcohol, in which several tens of percent of acetate groups remain, and fully saponified polyvinyl alcohol, in which only a few percent of acetate groups remain.
• the mixing ratio of silicon alkoxide and its hydrolysate to the water-soluble polymer is preferably in the range of 0.25 to 4.00 by mass (silicon alkoxide and its hydrolysate/water-soluble polymer), and more preferably 0.67 to 2.50. If it is less than 0.25, the silicon network of the coating layer may be insufficient, resulting in reduced water resistance, and if it exceeds 4.00, the coating layer may become hard and brittle, resulting in reduced gas barrier properties.
• the thickness of the coating layer is usually 0.01 to 50 ⁇ m, preferably 0.1 to 5 ⁇ m. If it is less than 0.01 ⁇ m, it may be difficult to obtain a uniform coating film and gas barrier properties, while if it is too thick, exceeding 50 ⁇ m, cracks are likely to occur, and as a result, gas barrier properties may be impaired.
• the coating amount (after drying) of the coating layer is preferably about 0.01 to 1 g/ m2 .
• the method for applying the coating layer is not particularly limited, and any known method can be used. For example, dip coating, roll coating, gravure coating, reverse coating, air knife coating, wire bar coating, etc. can be used.
• the drying method after coating is not particularly limited, and any known method can be used.
• hot air drying hot roll drying, microwave irradiation, high frequency irradiation, infrared irradiation, UV irradiation, etc. can be used.
• the conditions for the drying process after application of the coating layer are not particularly limited, and may be any time that does not affect productivity at a temperature below the melting point of the film substrate.
• the drying time is preferably 30 seconds or less, and more preferably 10 seconds or less.
• the drying temperature is preferably 180°C or higher, and more preferably 200°C or higher. Processing at a high temperature for a short period of time is preferable, as it provides excellent water vapor barrier properties while maintaining productivity.
• the gas barrier laminate film when used as a packaging material, it is preferable to form a heat-sealable resin layer called a sealant.
• the heat-sealable resin layer is usually provided on the coating layer, but it may also be provided on the outside of the base film (the side opposite to the side on which the coating layer is formed).
• the heat-sealable resin layer is usually formed by extrusion lamination or dry lamination.
• the thermoplastic polymer that forms the heat-sealable resin layer may be any that can fully exhibit sealant adhesion, such as polyethylene resins such as HDPE, LDPE, and LLDPE, and polypropylene resins. Ethylene-vinyl acetate copolymers, ethylene- ⁇ -olefin random copolymers, ionomer resins, etc. can also be used.
• the gas barrier laminate film may have at least one or more layers of a printed layer, other plastic substrate, and/or paper substrate laminated between or on the outside of the covering layer or substrate film and the heat-sealable resin layer.
• the printing ink for forming the printing layer water-based and solvent-based resin-containing printing inks can be preferably used.
• resins used in the printing ink include acrylic resins, urethane resins, polyester resins, vinyl chloride resins, vinyl acetate copolymer resins, and mixtures thereof.
• the printing ink may contain known additives such as antistatic agents, light blocking agents, ultraviolet absorbers, plasticizers, lubricants, fillers, colorants, stabilizers, lubricants, defoamers, crosslinking agents, anti-blocking agents, and antioxidants.
• the printing method for providing the printing layer is not particularly limited, and known printing methods such as offset printing, gravure printing, and screen printing can be used. To dry the solvent after printing, known drying methods such as hot air drying, hot roll drying, and infrared drying can be used.
• plastic substrates or paper substrates from the viewpoint of obtaining sufficient stiffness and strength of the laminate, paper, polyester resin, polyamide resin, biodegradable resin, etc. are preferably used. Also, in order to obtain a film with excellent mechanical strength, oriented films such as biaxially oriented polyester film and biaxially oriented nylon film are preferred.
• a gas barrier laminate film with an inorganic thin film layer is used as a packaging material
• nylon 6, nylon 66, metaxylene adipamide, etc. are usually used as the type of nylon.
• the thickness of the nylon film is usually 10 to 30 ⁇ m, preferably 15 to 25 ⁇ m. If the nylon film is thinner than 10 ⁇ m, it may be insufficient in strength, while if it exceeds 30 ⁇ m, it may be too stiff and unsuitable for processing.
• a biaxially stretched film with a stretch ratio in each of the length and width directions is usually 2 times or more, preferably about 2.5 to 4 times.
• the gas barrier laminate film of the present invention also includes embodiments having the above-mentioned layers other than the coating layer and inorganic thin film layer.
• the method for producing the gas barrier laminate film of the present invention comprises the steps of: A step of forming an inorganic thin film layer on at least one surface of a polyester substrate film; The method includes a step of forming a coating layer by applying a coating liquid containing silicon alkoxide, a hydrolysate of silicon alkoxide, and a water-soluble polymer onto the inorganic thin film layer, The silicon alkoxide and the silicon alkoxide hydrolysate are stored at 0 to 20° C. for 1 to 15 days before being mixed with the water-soluble polymer.
• the inorganic compound used in the inorganic thin film layer, the method for forming the inorganic thin film layer, and the film thickness of the inorganic thin film layer are as described above.
• a step of forming an adhesive layer on the polyester substrate film may be included.
• the resin composition used for the adhesion layer, the method for forming the adhesion layer, and the film thickness of the adhesion layer are as described above.
• the silicon alkoxide, the hydrolysate of the silicon alkoxide, the temperature and time of standing, the water-soluble polymer, the mixing ratio of the silicon alkoxide and its hydrolysate to the water-soluble polymer, the film thickness of the coating layer, the method of applying the coating layer, and the drying method after application of the coating layer are as described above.
• the manufacturing method of the gas barrier laminate film of the present invention can include a step of forming various layers that are provided in known gas barrier laminate films, as necessary. Such layers are as described above.
• the peak intensity P1 was calculated from the peak height perpendicularly connecting the baseline of zero absorbance and the peak top of the peak occurring near 1070 cm ⁇ 1
• the peak intensity P2 was calculated from the peak height perpendicularly connecting the baseline of zero absorbance and the peak position at 1220 cm ⁇ 1 .
• Equipment "ALPHA E” manufactured by Bruker Optics Co., Ltd.
• Optical crystal Ge Incident angle: 45° Resolution: 8 cm -1 Number of times accumulated: 64
• Example 1 Preparation of Coating Liquid 1 for Adhesion Layer The materials were mixed in the following blending ratio to prepare a coating liquid (resin composition for adhesion layer). Water 54.40% Isopropanol 25.00% Oxazoline group-containing resin (A) 15.00% Acrylic resin (B) 3.60% Urethane resin (C) 2.00%
• the film was introduced into a tenter while drying, preheated at 100°C, stretched 4.0 times in the transverse direction at 120°C, and heat-treated at 225°C while performing 6% relaxation in the transverse direction to obtain a laminated film in which an adhesive layer of 0.020 g/ m2 was formed on a biaxially stretched polyester film with a thickness of 12 ⁇ m.
• a composite inorganic oxide layer of silicon dioxide and aluminum oxide was formed as an inorganic thin film layer on the adhesive layer surface of the laminated film obtained in (2) above by electron beam deposition.
• Particulate SiO 2 (purity 99.9%) and Al 2 O 3 (purity 99.9%) of about 3 mm to 5 mm were used as deposition sources.
• the film thickness of the inorganic thin film layer (SiO 2 /A1 2 O 3 composite oxide layer) was 13 nm.
• Coating Solution 2 Used for Coating Layer
• the following coating solution sub-materials (A) and (B) were mixed in a mass ratio of 4/6 to prepare Coating Solution 2.
• Coating Layer Coating Liquid 2 was applied onto the inorganic thin film layer of the vapor-deposited film obtained in (3) by wire bar coating, and dried at 220° C. for 10 seconds to obtain a coating layer.
• the coating amount after drying was 0.30 g/m 2 (Dry).
• a gas barrier laminate film was produced that had an adhesive layer, an inorganic thin film layer, and a coating layer on a substrate film.
• the resulting gas barrier laminate film was evaluated for water vapor permeability, haze, and IR intensity as described above. The results are shown in Table 1.
• Examples 2 to 3 Comparative Examples 1 to 5> A gas barrier laminate film was produced in the same manner as in Example 1, except that the storage environment of the coating liquid auxiliary material (A) used in Coating Liquid 2 was changed as shown in Table 1. The water vapor permeability, haze, and IR intensity of the obtained gas barrier laminate film were evaluated as described above. The results are shown in Table 1.
• the gas barrier laminate films obtained in Examples 1 to 3 had excellent water vapor permeability and transparency. In contrast, the gas barrier laminate films obtained in Comparative Examples 1 to 5 had poor water vapor permeability and transparency.
• the present invention provides a gas barrier laminate film having excellent water vapor barrier properties and transparency, and a method for producing the same.
• a gas barrier laminate film has the advantages of being easy to produce, being economical and stable in production, and easily obtaining uniform properties. Therefore, such a gas barrier laminate film can be widely used not only for food packaging, but also for packaging various foods, medicines, industrial products, etc., and also for industrial applications such as solar cells, electronic paper, organic EL elements, and semiconductor elements.

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• 2023
  • 2023-09-28 WO PCT/JP2023/035438 patent/WO2024075635A1/ja not_active Ceased
  • 2023-09-28 JP JP2024555767A patent/JPWO2024075635A1/ja active Pending
  • 2023-10-02 TW TW112137632A patent/TW202421423A/zh unknown

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