JPH0250838A - Coated polyester film and vapor deposited film using the same - Google Patents

Abstract

PURPOSE:To enhance the adhesiveness to an inorg. vapor deposition layer of a metal or the like especially in the presence of water by forming the coating layer formed to at least the single surface of a base film from a composition based on specific thermoplastic polyurethane. CONSTITUTION:In a coated polyester film wherein a coating layer is formed to at least the single surface of a base film composed of a polyester resin, the coating layer is formed from a composition substantially based on water- insoluble water-dispersible thermoplastic polyurethane which is obtained from polyester polyol, dissocyanate and, if necessary, a low-molecular compound having two or more active hydrogen atoms. Said polyester polyol is obtained from dicarboxylic acids containing 50mol.% or more of aliphatic dicarboxylic acid and glycols and has glass transition temp. of 40 deg.C or less. The above mentioned composition is formed into an aqueous dispersion to be applied to a base film. The amount of the composition present on the unit area m<2> of the coated film is 0.01-5g, pref., 0.02-1g.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a polyester film that has excellent adhesion to a thin layer to be formed on its surface even in the presence of water, and a method for vapor deposition using the same. Regarding polyester film.

(Prior art) Polyester film on which metal or metal oxide is vapor-deposited,
In particular, metal-deposited polyethylene terephthalate film has gas barrier properties, moisture impermeability, visible and ultraviolet light shielding properties,
It is used for a variety of purposes due to its excellent heat ray reflection properties. For example, it is used in packaging materials for food and industrial parts, decorative materials, window glass shielding materials, materials for gold and silver thread, and materials for various protective coatings. However, the adhesion between the base layer and the vapor deposited layer of the vapor deposited film, especially in the presence of water, is not necessarily sufficient. For example, when food is packaged with a heat seal film in which a heat seal layer made of a polyolefin resin is laminated on the surface of a metal-deposited polyester base film.

When boiling treatment is performed for the purpose of sterilization, there is a drawback that the vapor-deposited layer easily peels off.

As a method for improving the adhesive strength between a polyester base film and a metal vapor deposited layer, 1, for example, as described in Japanese Patent Publication No. 55232 and Japanese Patent Application Laid-open No. 56-16549, other copolymer compositions are mixed in addition to polyester. A method for preparing a base film is disclosed. Furthermore, JP-A-57-8
No. 7357 discloses a method of physically changing the surface condition of a base film.

Japanese Patent Publication No. 59-51424 discloses a method in which a solution of a specific resin composition is applied to the surface of a base film to form a layer of the resin composition. However, even if these methods are adopted, the adhesion between the base film or laminate film and the metal vapor-deposited layer is still not sufficient, especially in the presence of water (especially hot water). is insufficient. Furthermore, using the method described above,
In the method of applying a resin composition solution described in Japanese Patent No. 424, since an organic solvent is used, there are concerns about flammability and toxicity.

Involves work hazards. It is also unfavorable from the viewpoint of pollution generation and energy saving.

Methods for increasing the adhesion between a base film and a coating layer formed on its surface in the presence of water include 7, for example, Japanese Patent Publication No. 55-45835 and Japanese Patent Publication No. 55-128.
No. 70 discloses a method for improving the adhesion between a base film and a printed layer. According to this method, polyester having a specific composition is blended into the base film.

However, this method is relatively effective when the layer laminated on the base film is a printed layer, but when the layer laminated on the base film is a metal vapor-deposited layer, the presence of water under,
In particular, the adhesion in the presence of hot water is still not sufficient.

As an undercoat to improve the adhesion between a polyester base material and a layer laminated thereon, for example, JP-A-48-3748
No. 0 discloses specific polyester resins and polyether resin compositions. These resin compositions have good adhesion to the polyester base material, but often have insufficient adhesion to the metal vapor deposited layer to be laminated. Furthermore, since an organic solvent is used when applying the resin composition to a substrate, it is flammable and toxic and poses operational hazards, as in the case of Japanese Patent Publication No. 59-51424.

As a method of forming an undercoat layer on a base film without using an organic solvent, Japanese Patent Publication No. 54-16557 discloses a method of applying an aqueous solution containing a composition whose ingredients have been changed to water-soluble ones. has been done.

However, since the compositions used are essentially water-soluble, there is a drawback, for example, that the resulting vapor-deposited films have poor water resistance. Also in the manufacturing process, aqueous solvents have the disadvantage of poor wetting with hydrophobic base films (and difficulty in obtaining a uniform coating film).

In this way, adhesion with inorganic vapor deposited layers such as metals.

Currently, there are no polyester films or vapor-deposited films using the same that have good adhesion, particularly in the presence of water, and for which the resulting product can be subjected to boiling treatment.

(Problem to be solved by the invention) The present invention solves the above-mentioned conventional problems.

The purpose of this is to improve interlayer adhesion with the metal vapor deposited layer.
The object of the present invention is to provide a polyester film that has excellent adhesiveness, especially in the presence of water, and a vapor-deposited film using the same.

(Means and effects for solving the problems) The coated polyester film of the present invention is a coated polyester film in which a coating layer is formed on at least one side of a base film made of a polyester resin; The polyurethane is made of a polyester polyol, a diisocyanate, and optionally a low-molecular compound having two or more active hydrogen atoms. The polyester polyol is obtained from dicarboxylic acids containing an aliphatic dicarboxylic acid in a proportion of 50 mol % or more, and glycols, and has a glass transition temperature of 40° C. or less.

The vapor-deposited polyester film of the present invention is formed by providing a thin inorganic layer on the surface of the coating layer of the coated polyester film.

As the base film used in the coated polyester film of the present invention, a film of thermoplastic polyester resin, for example, a film of polyethylene terephthalate, polybutylene terephthalate, polyethylene nuclate, etc. is suitable.

In particular, a copolyester film in which 80% or more of its components correspond to polyethylene terephthalate (that is, 80% or more of the total components are terephthalic acid components and ethylene glycol components) or a polyester blend containing polyethylene terephthalate in a proportion of 80% or more A film is preferably used. The polyester components other than the polyethylene terephthalate component in such a copolymerized polyester film or polyester blend film may be any polyester component.

As the dicarboxylic acid component constituting such a polyester, aromatic, aliphatic, and alicyclic dicarboxylic acids can all be used. As aromatic dicarboxylic acids,
Isophthalic acid, orthophthalic acid, 2,6-naphthalene dicarboxylic acid, etc., aliphatic dicarboxylic acids include succinic acid, adipic acid, sebacic acid, oxalic acid, etc., and alicyclic dicarboxylic acids include ■, 3- Examples include cyclopenkune dicarboxylic acid and 1,4-cyclohexane dicarboxylic acid. As the aromatic dicarboxylic acid, some oxyacids such as p-hydroxybenzoic acid are preferably used. The glycol component constituting the above polyester may be an aliphatic glycol having 2 to 8 carbon atoms or a glycol having 6 to 8 carbon atoms.
12 alicyclic glycols are preferred. Such glycols include ethylene glycol 1,2-propanediol 13-propanediol 1,4-butanediol neopentyl glycol 1,6-hexanediol 12-cyclohexane dimetatool 1,3-cyclohexane dimetatool 1,4- Examples include cyclohexane dimetatool, P-xylene glycol, diethylene glycol, and triethylene glycol. In addition, it is also possible to use polyether glycol as the aliphatic glycol.

These include polyethylene glycol, polypropylene glycol, and polytetramethylene glycol.

These acid components and dicarboxylic acid components are polymerized (or copolymerized) by two conventional methods to prepare a polyester. This polyester is mixed as appropriate, and a film (base film) is usually obtained by melting and extrusion, or by dissolving it in a solvent and casting. The base film used is as required.

- axially or biaxially stretched;

The polyurethane which is the main component in the composition used for the coating layer formed on the surface of the base film is a substantially water-insoluble and water-dispersible thermoplastic polyurethane. Here, "substantially water-insoluble" means that even if the polyurethane to be tested is immersed in hot water at 80°C and stirred, the polymer does not dissipate in the hot water. More specifically, when the polyurethane to be tested is made into chips and placed in a large excess of hot water (80°C) and stirred for 24 hours, the weight of the polymer decreases by 5% by weight or less. It means that. As such polyurethane.

A polyurethane obtained from a polyester polyol and a diisocyanate; or a polyurethane obtained by using the polyurethane as a prepolymer and reacting it with a low-molecular compound having two or more active hydrogens such as a diol or diamine is used.

The above polyester polyol is obtained by reaction of dicarboxylic acid and glycol. Among these, dicarboxylic acids include aromatic and aliphatic acids.

Although any alicyclic dicarboxylic acid may be used, it is necessary that the aliphatic dicarboxylic acid is contained in an amount of 50 mol% or more, preferably 70 mol% or more. Succinic acid is an aliphatic dicarboxylic acid.

Adipic acid, sebacic acid, oxalic acid, etc. are used.

Among dicarboxylic acids other than aliphatic acids, examples of aromatic dicarboxylic acids include terephthalic acid, isophthalic acid, orthophthalic acid, and 216-naphthalenedicarboxylic acid. Some oxyacids such as p-hydroxybenzoic acid may also be used. Examples of the alicyclic dicarboxylic acids include (1), 3-cyclopenkune dicarboxylic acid, 1,2-cyclohexane dicarboxylic acid, 1,3 cyclohexane dicarboxylic acid, and (1), 4-cyclohexane dicarboxylic acid. If the aliphatic dicarboxylic acid is too small, the adhesion of the coating film formed from the resulting polyurethane-containing composition will be poor in the presence of water (particularly in the presence of hot water). Furthermore, in the case where a coating film is formed on an unstretched base film, stretching of the obtained coating film results in poor followability of the coating film to the base film.

As the glycol component forming the polyester polyol, both aliphatic glycols and alicyclic glycols having 2 or more carbon atoms can be used. Alkylene glycols having 4 or more carbon atoms (eg, butanediol, hexanediol).

It is preferable to use alicyclic glycols (for example, cyclohexane dimetatool) or bisphenol compounds together.

1 using the above dicarboxylic acid component and polyhydric alcohol component.
Polyester polyols are usually prepared by a melt polycondensation method. For example, a direct esterification method in which each of the above components is directly reacted, water is distilled off and esterified, and triple condensation is performed; or the dialkyl ester of the dicarboxylic acid component and the glycol component are reacted to distill off the alcohol and esterify. It is prepared by a transesterification method that involves exchange and polycondensation. In addition to the melt polymerization method, a solution polycondensation method, an interfacial polycondensation method, etc. may also be employed.

The water-insoluble and water-dispersible polyester polyol thus obtained has a glass transition temperature (Tg) of 4.
It is necessary that the temperature is below 0°C, preferably below 20°C. If the glass transition temperature exceeds 40°C, the resulting composition containing polyurethane will have poor film-forming properties when applied to the base film, resulting in insufficient adhesion between the resulting coating layer and the base film. As a result, the adhesion between the obtained coating film and the vapor deposited layer laminated thereon is also poor.

The diisocyanates reacted with the polyester polyol obtained in this way include aromatic, aliphatic,
and alicyclic diisocyanate-1. For example, aromatic diisocyanates such as toluene diisocyanate are suitable. A coating film formed by a composition containing a polyurethane obtained using such an aromatic diisocyanate has high strength, and also has excellent adhesion in the presence of water with the vapor-deposited layer of the resulting coating film.

A polyurethane is obtained by reacting the above-mentioned polyester polyol with the above-mentioned diisocyanate by a conventional method. Furthermore, it is also possible to extend the chain by reacting a low-molecular compound (chain extender) having two or more active hydrogens, such as a diol or diamine. The above diol is 1,
6-hexanediol and the like can be used, and as the diamine, hexamethylene diamine and the like can be used.

In addition to the polyurethane described above, a resin component having crosslinking properties may be added to the composition forming the coating layer. Examples of such resins include melamine-based, epoxy-based, aziridine-based, and urethane-based resins. By including these, the strength of the resulting coating layer is increased. However, the stability of the aqueous dispersion of the composition containing these decreases; when the resulting coating film is continuously vapor-deposited while being cooled, sufficient adhesion with the vapor-deposited layer cannot be obtained; When metal vapor deposition is applied to a coating film, if it is treated with hot water, it loses its metallic luster and becomes transparent; and it has the disadvantage that it is difficult to melt or dissolve the obtained coating film or vapor deposited film and reuse it. be. Therefore.

The above-mentioned crosslinking component is added as appropriate depending on the purpose.

The composition may further contain other additives. Examples of these include inorganic inert particles such as silica, calcium carbonate, kaolinite, alumina, talc, and barium sulfate; organic inert particles such as benzoguanamine resins and polystyrene resins (each with a particle size of 0.01 to 10 μm).
m), and by adding these, slipping properties and anti-blocking properties can be improved. Further, pigments; organic and inorganic antistatic agents; preservatives; antifoaming agents; ultraviolet absorbers and the like may be used as necessary. The type and amount of the additives are not particularly limited as long as they do not significantly impede the interlayer adhesion between the resulting coated film and the vapor-deposited layer in the presence of water.

The composition to be coated onto the base film is made into an aqueous dispersion by various methods. For example, a method in which fine particles of the polyurethane and an emulsifier are added to water and dispersed under strong stirring; when synthesizing the polyurethane, a polyurethane (prepolymer) having an isocyanate group at the end;
A method in which a chain extender and an emulsifier are reacted with strong stirring in water to achieve simultaneous dispersion and polymerization using mechanical shearing force; hydroxyl groups, amino groups,
A method of imparting self-emulsifying properties and dispersing by introducing an ionic group such as a carboxyl group is used. Considering the water resistance of the resulting coating film, a method that does not use an emulsifier is desirable. Various additives are added to the obtained polyurethane dispersion as necessary, or these additives are appropriately added in the above-mentioned dispersion step to prepare a uniform aqueous dispersion.

The aqueous dispersion is applied onto the base film by a known method. For example, the above dispersion is applied onto an unstretched base film obtained by melting and extrusion, or a base film obtained by uniaxially or biaxially stretching the unstretched film, and if necessary, further stretching and post-stretching are performed. Heat treatment is performed. A biaxially oriented film obtained by coating a dispersion liquid on an unstretched or -axially stretched base film, further -axially or biaxially stretching, and heat treatment, improves the adhesion of the coating layer,
This is preferable from the point of view of economy. Particularly from the viewpoint of workability, it is preferable to apply a dispersion liquid onto a -axially stretched base film and then stretch the dispersion in a direction orthogonal to the second direction to obtain a biaxially stretched film. Any known method such as a roll coating method (gravure method, reverse method, etc.), a knife coating method, a rod coating method, a nozzle coating method, an air knife coating method, etc. can be adopted for coating the above-mentioned aqueous dispersion. The amount of coating is determined depending on the purpose, but usually the amount of the composition present on the unit area (m2) of the coated film finally obtained by two-wheel stretching etc.
0.01-5g, preferably 0.02-Ig. If the coating amount is less than 0.01 g/m2, the desired effect cannot be obtained, and if it exceeds 5 g/m2, blocking of the resulting coated film is likely to occur. When the obtained coated film is subjected to metal vapor deposition, there is also a drawback that the gloss of the vapor-deposited surface is lost when it is treated with hot water. When applying the aqueous composition dispersion, the surface of the base film may be subjected to corona treatment or physical or chemical surface treatment, if necessary.

An inorganic substance is deposited on the surface of the coated polyester film of the present invention thus obtained. Examples of the inorganic substance to be thinly deposited include metals, metal oxides, and inorganic oxides other than metals. The above metals include gold, silver, aluminum, zinc, tin, and copper.

Nickel, iron, cobalt chromium, manganese, palladium, titanium, indium, etc. are used.

In particular, aluminum is widely used. A silicon oxide compound or the like is used as the inorganic oxide. These may be used alone or in combination of two or more.

These inorganic substances are deposited on the surface of the coating film by a conventional method. A vacuum evaporation method or the like is preferably used. The vapor-deposited polyester film thus obtained is used for various purposes.

In particular, sheets or films made of various resin materials can be laminated on a vapor-deposited layer obtained by vapor-depositing metals or metal oxides on the coating layer, and this can be suitably used for food packaging materials, etc. Such a laminate does not peel off even when immersed in hot water. As the resin material constituting the sheet or film to be laminated, polyethylene, polypropylene, various ionomers, ethylene-vinyl acetate copolymer, polyvinylidene chloride copolymer, polyester, polyamide, etc. are used.

As described above, the coated polyester film of the present invention has excellent interlayer adhesion between the base material and the coating layer, and between the coating layer and the layer formed on the surface thereof, particularly the vapor deposited layer. Therefore, the vapor-deposited polyester film of the present invention obtained using this film has extremely excellent adhesion of the vapor-deposited layer, particularly in the presence of water. Therefore, such a vapor-deposited polyester film is particularly suitable for use as a food packaging film that is subjected to hot water sterilization treatment.

(Margin below) (Example) The present invention will be described below with reference to examples.

(8) Preparation of polyurethane and aqueous dispersion Adipic acid as the dicarboxylic acid component; and 60 mol% of 1,4-butanediol (of the glycol component) as the glycol component, and propylene oxide (1 mol) of bisphenol A. Using 40 mol% of adduct, Tg is -5
℃ polyester (polyester polyol) was obtained.

This polyester was treated with toluene diisocyanate to obtain a urethane polymer. This was used as a prepolymer, and 1,6 hexanediol was applied to extend the chain and aminocarboxylate was reacted at the terminal end to obtain a water-insoluble and water-dispersible polyurethane. This was dispersed in hot water with stirring to obtain a 25% aqueous dispersion.

The aqueous polyurethane dispersion was added to a mixture of equal amounts of ion-exchanged water and isopropyl alcohol to obtain a dispersion having a solid content of 5%.

(B) Preparation of vapor deposited film: Polyethylene terephthalate was melt extruded at 280 to 300°C and cooled with a cooling roll at 15°C to obtain an unstretched film with a thickness of about 150 μm. This unstretched film was stretched 3.5 times in the longitudinal direction between a pair of rolls having different peripheral speeds at 85°C.

Next, the aqueous dispersion containing the polyurethane obtained in section (Δ) was applied using a roll coater.

The film was dried with hot air at 70°C, then stretched 3.5 times in the transverse direction at 98°C using a tenter, and further heat-set at 200 to 210°C to obtain a biaxially stretched coated polyester film with a thickness of 12 μm. The final coating amount of the coating agent (coating composition) was approximately 0.04 g/m2. Table 1 shows the composition, properties, etc. of the resin component forming the coating layer of the obtained coating film. Aluminum was deposited on the surface of the coating layer of this coating film to a thickness of 600 mm.

(C) Performance evaluation of vapor-deposited film = After laminating an unstretched polypropylene (PP) sheet with a thickness of 60 μm on the surface of the vapor-deposited layer of the vapor-deposited film obtained in section (B) by a normal dry lamination method, aging treatment was performed. Ta. The obtained laminate was cut into strips with a width of 15 mm and immersed in boiling water at 95° C. or higher for 30 minutes (boiling treatment). An experiment in which another sample was immersed in high-pressure water at 120° C. for 30 minutes (retort treatment) was also conducted.

Partially peeling off the PP film and the base film at the end of the untreated, boiled and retorted laminate;
The peeled ends were each fixed to a Tensilon chuck manufactured by Toyo Baldwin, and pulled in the length direction at a speed of 200 mm/min to perform T-peeling. A separate peeling experiment was conducted under similar conditions with water droplets applied to the peeled interface. Table 2 shows the interlayer adhesive strength (g/15mm) of each.

The procedure was the same as in Example 1 except that isophorone diisocyanate was used instead of toluene diisocyanate.

Implemented coal y 50 mol% of adipic acid as a dicarboxylic acid component.

The procedure was the same as in Example 1 except that 20 mol% of sebacic acid and 30 mol% of terephthalic acid were used to obtain a polyester polyol with a Tg of 5°C.

Using 50 mol% of terephthalic acid and 50 mol% of isophthalic acid as the general dicarboxylic acid component, and 70 mol% of ethylene glycol and 30 mol% of diethylene glycol as the glycol component, Tg was 55°C according to Example 1. A polyester (polyester polyol) was obtained. This was treated with hexamethylene diisocyanate to obtain a urethane polymer, and the following procedure was carried out in accordance with Example 1.

Reference I A polyether type polyurethane was prepared by using poly(oxytetramethylene) glycol instead of polyester polyol and reacting it with toluene diisocyanate. This was treated with hexamethylene diamine as a chain extender to produce the following.

It was carried out according to Example 1.

The procedure was the same as in Example 2 except that sorbitol polyglycidyl ether was added as an epoxy curing agent to the obtained polyurethane at a solid content of 20% by weight, and a quaternary ammonium salt was added as a catalyst.

This is the same as Example 1 except that the aqueous dispersion containing polyurethane was not applied.

(The following is a blank space) It can be seen from Tables 1 and 2 that the vapor-deposited polyester film of the present invention exhibits excellent adhesion between the base film and the vapor-deposited layer even in the presence of hot water.

On the other hand, the film of Comparative Example 4 in which the coating layer made of the composition containing polyurethane of a predetermined composition was not formed did not have such an effect. When an aliphatic dicarboxylic acid is not used as the dicarboxylic acid component of the polyester polyol forming the polyurethane in the composition forming the coating layer, and the Tg of the polyester polyol is high,
A sufficient adhesion effect between the base material and the deposited layer, especially in the presence of hot water, cannot be obtained. The coating layer is also not uniform, so a uniform deposited layer cannot be obtained. (Comparative Example 1). When the polyurethane is prepared using a polyether polyol rather than a polyester polyol (Comparative Example 2), a sufficient adhesive effect is also not obtained. Furthermore, even if the composition of the polyurethane resin is within the claimed range, if a crosslinking agent is used in combination to make the resin composition thermosetting, a sufficient adhesion effect between the base layer and the deposited layer can be obtained, but the coating The layers are not uniform and therefore a uniform deposited layer is not obtained. Retort treatment also has the disadvantage that it loses its metallic luster and becomes transparent.

(Effects of the Invention) According to the present invention, as described above, a coated polyester film having excellent adhesion to a layer formed on the surface thereof, particularly an inorganic vapor-deposited layer, and a vapor-deposited film using the same can be obtained. The adhesive strength between the vapor deposited layer and the base film is sufficient even in the presence of water, especially hot water. Such vapor-deposited films are used for food packaging films, decorative materials, various protective films, etc., and are particularly suitable for food packaging films that are subjected to heat treatment with hot water.

that's all

Claims (1)

[Scope of Claims] 1. A coated polyester film having a coating layer formed on at least one side of a base film made of a polyester resin, wherein the coating layer is substantially water-insoluble and water-dispersible. It is formed from a composition mainly composed of a plastic polyurethane, the polyurethane is obtained from a polyester polyol, a diisocyanate, and optionally a low-molecular compound having two or more active hydrogens, and the polyester polyol contains 50 moles. A coated polyester film obtained from dicarboxylic acids containing an aliphatic dicarboxylic acid in a proportion of % or more; and glycols, and having a glass transition temperature of 40° C. or less. 2. The coated polyester film according to claim 1, which is oriented in at least one axis. 3. An inorganic vapor-deposited layer is provided on the surface of the coating layer of the coated polyester film according to claim 1.
Vapor-deposited polyester film. 4. The vapor-deposited polyester film according to claim 3, wherein the coated polyester film is oriented in at least one axis.