JPH09267457A - Non-stretched film for laminating metal sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain non-stretched film for laminating a metal sheet, excellent in impact resistance at low temperature, and especially good in adhesiveness to the metal sheet and deep drawability by laminating a second layer consisting of polycarbonate having specific structure, and a third layer consisting of polyester are laminated on a first layer consisting of polyester. SOLUTION: A non-stretched film for laminating a metal sheet is obtained by laminating a second layer having polycarbonate as main component consisting of a repeating unit expressed by the formula I (R<1> and R<2> are each an H atom, a 1-5C allkyl group or 5-6C cycloalkyl group, provided that R<1> and R<2> may form the 5-6C cycloakyl group together with a C atom be bonded therewith; R<3> and R<4> are each a 1-5C alkyl group, a phenyl group or a halogen atom; and (m) and (n) are each 0, 1, and 2), and a third layer consisting of polyester having ethylene terephthalale as a main repeating unit on a first layer consisting of polyester having ethylene terephthalate as main repeating unit.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a non-stretched film for laminating metal plates, and more specifically, it exhibits excellent moldability when it is laminated with a metal plate and subjected to a can-making process such as a drawing process. Of excellent film formability (flavorability) and impact resistance at low temperatures, as well as good film forming properties (extrusion moldability),
In particular, the present invention relates to a non-stretched film for laminating a metal plate, which is excellent in adhesiveness to a metal plate and deep drawability and is suitable for use in beverage cans, food cans and the like.

[0002]

2. Description of the Related Art Metal cans have been generally coated to prevent corrosion of the inner and outer surfaces. Recently, organic solvents have been used for the purpose of simplifying the process, improving hygiene, and preventing pollution. The method of laminating a thermoplastic resin film on a metal plate such as tin, tin-free steel, aluminum, etc., and then drawing cans has been widely used. Is coming.
As such a thermoplastic resin film, a polyester film is usually used, and many proposals have been made so far.

For example, JP-A-56-10451 and JP-A-1-192546 disclose that a biaxially oriented polyethylene terephthalate film is laminated on a metal plate via an adhesive layer of a low-melting polyester to form a can-forming material. It is disclosed for use. However, although the biaxially oriented polyethylene terephthalate film is excellent in heat resistance and aroma retaining property (flavor property), its processability is insufficient and the film is whitened (small Occurrence of cracks) and fracture may occur.

[0004] Also, JP-A-1-192545 and JP-A-2-57339 disclose that a non-crystalline or extremely low-crystalline aromatic polyester film is laminated on a metal plate and used as a can-making material. It has been disclosed. However, an amorphous or extremely low-copolymerized aromatic polyester film has good moldability, but is inferior in fragrance retention (flavor), and can be used for printing after can-making, retort sterilization, and the like. It may be easily embrittled by post-treatment and further long-term storage, and the film may be easily broken by impact from the outside of the can.

The present inventors have conceived of using a copolymerized polyester film to solve such a problem, and have made various proposals so far.

As a result, the use of a specific copolymerized polyester film has solved the problems of molding processability, heat resistance, retort resistance, and fragrance retention (flavor), but the impact resistance at low temperatures has been reduced. However, the impact resistance, especially at a low temperature of 5 ° C. or less, has not been sufficient, and there is room for improvement. Poor impact resistance at low temperatures means that if the product is handled in a cooled state, such as a metal can for juice or soft drinks, the film may crack when dropped and impacted. Is a big problem.

On the other hand, in order to solve such a problem of the polyester film, that is, the problem of poor impact resistance at low temperatures, it has been proposed to use a film in which polyester and polycarbonate are blended ( JP-A-6-255022. When such a blend film is used, the impact resistance at low temperatures is certainly improved, but a new problem arises in that the fragrance retention (flavor) and the adhesion to a metal plate are poor. Further, when an extruded film is stretched to increase impact resistance, it breaks and cannot be satisfactorily stretched, which makes it difficult to use as a biaxially stretched film.

[0008]

SUMMARY OF THE INVENTION The object of the present invention is to solve the problems of the prior art, particularly the problems of the film composed of the blend composition of polyester and polycarbonate, and to improve the impact resistance at low temperature. Excellent stretchability, good taste retention (flavorability), good film-forming property (extrusion moldability), especially improved adhesion to metal plates and deep drawability To provide a film.

[0009]

As a result of intensive studies to solve the above problems, the present inventors formed a first layer made of a specific polyester and a polycarbonate or a composition made of a polycarbonate and a polyester. A second layer is laminated, and a third layer made of a specific polyester is further laminated on the second layer to form a three-layer film, which is further laminated on a metal plate without stretching and is deep-drawn. It was found that the above problems can be solved by processing, and the present invention has been completed.

That is, in the present invention, the first layer (A) comprising a polyester having ethylene terephthalate as a main repeating unit and a polycarbonate substantially consisting of the repeating unit represented by the following general formula (1) or 55% by weight A polyester obtained by laminating the above polycarbonate and a second layer (B) formed of a composition comprising 45% by weight or less of polyester, and further comprising ethylene terephthalate as a main repeating unit on the second layer (B). It is a non-stretched film for laminating a metal plate, which is formed by laminating a third layer (C) consisting of.

[0011]

Embedded image

(Here, R ¹ and R ² are each a hydrogen atom, an alkyl group having 1 to 5 carbon atoms or a ring member having 5 to 5 carbon atoms.
And R ¹ and R ² may form a cycloalkyl group having 5 to 6 ring members together with the carbon atom to which they are attached, and R ³ and R ⁴ each have 1 to 5 carbon atoms. Represents an alkyl group, a phenyl group or a halogen atom, and m and n are each 0, 1 or 2. )

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, the polyester (A) having ethylene terephthalate as a main repeating unit constituting the first layer (A) is a polyester having at least 85 mol% of ethylene terephthalate repeating units. It is a polyester in which 90 mol% or more, more preferably 95 mol% or more, is composed of repeating units of ethylene terephthalate.

In the polyester (A), as the component which can be copolymerized as the third component, for example, as the acid component, an aromatic dicarboxylic acid such as isophthalic acid, phthalic acid, 2,6-naphthalenedicarboxylic acid, or adipine is used. Examples thereof include acids, azelaic acid, sebacic acid, aliphatic dicarboxylic acids such as decanedicarboxylic acid, and alicyclic dicarboxylic acids such as 1,4-cyclohexanedicarboxylic acid. Examples of alcohol components include diethylene glycol, 1,4-butanediol, Examples thereof include aliphatic diols such as 1,6-hexanediol and alicyclic diols such as 1,4-cyclohexanedimethanol. These can be used alone or in combination of two or more.

This polyester (A) has a melting point of 200.
It is preferably higher than ℃, more preferably 21
0 ° C. or higher. If polyester with a low melting point is used,
It is not preferable because it results in a film having poor heat resistance and impact resistance.

The above polyester has an intrinsic viscosity of preferably 0.5 to 0.9, particularly preferably 0.6 to 0.8, measured at 35 ° C. in orthochlorophenol.

This polyester can be produced by a conventionally known melt polymerization method, and it is preferable to use a germanium (Ge) compound catalyst as a catalyst for the polymerization reaction at this time, and a solid phase is used as a polymerization method in the final polymerization step. It is preferable to use a polymerization method from the viewpoint of reduction of oligomers.

In the present invention, the second layer may be composed of polycarbonate alone, or may be composed of a composition containing 55% by weight or more of the polycarbonate and 45% by weight or less of the polyester. It is preferable to mix 45% by weight or less of polyester with polycarbonate because the moldability during can molding is improved.

In the present invention, the polycarbonate used in the second layer (B) consists essentially of the repeating unit represented by the above formula (1). In the above formula (1), R ¹ and R ² are each a hydrogen atom, an alkyl group having 1 to 5 carbon atoms or a cycloalkyl group having 5 to 6 ring member carbon atoms,
Alternatively, R ¹ and R ² may combine with the carbon atom to which they are bound to form a cycloalkyl group having 5 to 6 ring carbon atoms.

The alkyl group having 1 to 5 carbon atoms may be linear or branched and is, for example, ethyl, n-propyl, iso-propyl, n-butyl, i.
Examples thereof include so-butyl and pentyl.

Examples of the cycloalkyl group having 5 to 6 ring carbon atoms include cyclopentyl and cyclohexyl.

R ³ and R ⁴ are each an alkyl group having 1 to 5 carbon atoms, a phenyl group or a halogen atom. Examples of the alkyl group having 1 to 5 carbon atoms are the same as those described above. As a halogen atom,
For example, fluorine, chlorine, bromine and the like can be mentioned.

M and n are 0, 1 or 2, respectively.

As the repeating unit represented by the above formula (1), for example, a bisphenol A type carbonate unit in which R ¹ and R ² are methyl and m and n are 0 can be exemplified as preferable ones.

The polycarbonate may be composed of the same repeating unit represented by the above formula (1), or may be composed of two or more different repeating units represented by the above formula (1).

This polycarbonate is usually prepared by reacting a corresponding dihydric phenol with a carbonate precursor such as phosgene in a solvent such as methylene chloride in the presence of a known acid acceptor or molecular weight modifier (interfacial polymerization method). ) Or a corresponding dihydric phenol and a carbonate precursor such as diphenyl carbonate by a transesterification reaction (melt polymerization method).

The polycarbonate can also be produced, for example, by the following method. That is, (a) a method in which a dihydric phenol is excessively reacted with a carbonate precursor during the production by the interfacial polymerization method,
(B) A method of end-capping when producing by the interfacial polymerization method,
(C) A method of adjusting the ratio of the dihydric phenol and the carbonate precursor during the production by the melt polymerization method, and (d) a method of adding a polyhydroxy compound in the latter stage of the polymerization reaction during the production by the melt polymerization method. , (E) Terminal OH amount 20 mol / 1
A method of increasing the amount of terminal OH by reacting the polycarbonate and the dihydric phenols by melt-mixing a polycarbonate of less than 0 ⁶ g and an appropriate amount of the dihydric phenols and adding a catalyst in some cases is adopted. .

The above polycarbonate has a viscosity average molecular weight of 10,000 to 40,000, more preferably 10,000 to
It is preferably 35,000.

Further, in the second layer (B) of the unstretched film of the present invention, the polyester (B) used together with the polycarbonate is a polyester having ethylene terephthalate as the main repeating unit used in the first layer (A). The same polyester (B-1) as described above can be used, and further, polyester (B-2) containing butylene terephthalate as a main repeating unit can be used together with the polyester.

The polyester (B-2) containing the butylene terephthalate as the main repeating unit is at least 85.
Mol% is a polyester composed of repeating units of 1,4-butylene terephthalate, preferably 90 mol%
As described above, more preferably 95 mol% or more is a polyester composed of repeating units of 1,4-butylene terephthalate.

In these polyesters, as a component which can be copolymerized as the third component, for example, as an acid component, aromatic dicarboxylic acid such as isophthalic acid, phthalic acid, 2,6-naphthalenedicarboxylic acid, adipic acid,
Aliphatic dicarboxylic acids such as azelaic acid, sebacic acid and decanedicarboxylic acid, and alicyclic dicarboxylic acids such as 1,4-cyclohexanedicarboxylic acid can be mentioned, and the alcohol component includes ethylene glycol (polyester B-2
A), diethylene glycol, 1,4-butanediol (for polyester B-1), an aliphatic diol such as 1,6-hexanediol, and an alicyclic diol such as 1,4-cyclohexanedimethanol. it can. These can be used alone or in combination of two or more.

These polyesters have a melting point of 200 ° C.
And more preferably a melting point of 210
℃ or above. It is not preferable to use a polyester having a low melting point because the resulting film has poor heat resistance and impact resistance.

Further, these polyesters have an intrinsic viscosity of 0.5 to 5 measured at 35 ° C. in orthochlorophenol.
It is preferably 1.6, and particularly preferably 0.6 to 1.5.

In the case of the above polyester (B-1), a Ge compound catalyst is used as a polymerization catalyst and a solid phase polymerization method is used in the final polymerization step, as in the case of the polyester (A) containing ethylene terephthalate as a main repeating unit. It is preferably produced by using. Examples of the Ge compound include (a) amorphous germanium oxide, (b) fine crystalline germanium oxide, (iii) a solution of germanium oxide dissolved in glycol in the presence of an alkali metal or an alkaline earth metal or a compound thereof, (D) A solution obtained by dissolving germanium oxide in water is preferred. In addition, when a polyester polymerized with an antimony (Sb) compound catalyst is used as the polyester (B-1), the decarboxylation reaction is promoted, carbon dioxide gas is generated, and bubbles are generated, so that the Sb compound catalyst can be used as much as possible. Good to avoid. Also, the use of a polyester polymerized with a titanium (Ti) compound catalyst is not preferable because it accelerates the transesterification reaction of the polycarbonate and further carbon dioxide gas is generated to cause foaming.

As the polyester (B) used in the second layer (B) of the unstretched film of the present invention, a polyester (B- containing ethylene terephthalate as a main repeating unit) is used.
1) and a polyester (B-2) containing butylene terephthalate as a main repeating unit are preferably mixed and used. In this case, the polyester (B-2) containing a butylene terephthalate as a main repeating unit has a terminal carboxyl group. The concentration is preferably 20 equivalents / 10 ⁶ g or less. It is more preferably 17 equivalents / 10 ⁶ g or less, and particularly preferably 15 to 5 equivalents / 10 ⁶ g.

The polyester (B-2) containing butylene terephthalate as the main repeating unit improves the dispersibility of the polycarbonate in the polyester phase, reduces the "melt runout" during extrusion molding, and improves the film-forming property. However, if the terminal carboxyl group concentration of the polyester is higher than 20 equivalents / 10 ⁶ g, the effect of improving the dispersibility with the polycarbonate and improving the film-forming property is unfavorable.

The second layer (B) of the non-stretched film of the present invention comprises 55% by weight or more of the above-mentioned polycarbonate and 4% or more.
It is preferably formed of a composition comprising 5% by weight or less of polyester (B). If the proportion of polyester exceeds 45% by weight, it becomes difficult to improve the impact resistance at low temperatures. The proportion of this polyester is preferably 30% by weight or less.

Further, the above polyester (B) used in the second layer (B) is a polyester (B-1) 10 to 90 containing ethylene terephthalate as the main repeating unit.
It is preferably composed of 10% by weight to 10% to 90% by weight of polyester (B-2) containing the above-mentioned butylene terephthalate as a main repeating unit. When the proportion of the polyester (B-2) containing butylene terephthalate as a main repeating unit exceeds 90% by weight of the polyester (B) component of the second layer (B), the film tends to be colored, and further, the polycarbonate and It is not preferable because carbon dioxide gas is generated by decarboxylation by reaction and bubbles are generated and the film forming property tends to be deteriorated. On the other hand, if it is less than 10% by weight, the effect of improving the dispersibility of the polycarbonate in the polyester phase is not large, and the effect of reducing the "melt shake" during extrusion molding is small, which is not preferable. The blending ratio (B-1 / B-2) of the polyester (B-1) having ethylene terephthalate as the main repeating unit and the polyester (B-2) having butylene terephthalate as the main repeating unit is (20 to 85% by weight). ) / (15
To 80% by weight), more preferably (40 to 8%)
0% by weight) / (20-60% by weight).

In the non-stretched film of the present invention, when the second layer (B) is composed of a composition of polycarbonate and polyester, the composition is 20 to 100 p.
It is desirable to contain the phosphorus compound at pm, preferably 40 to 100 ppm, and more preferably 40 to 50 ppm. This phosphorus compound suppresses the reaction between the polycarbonate and the polyester, and prevents the generation of carbon dioxide gas due to the coloring and decarboxylation of the film, but when the content is too large, butylene terephthalate is the main repeating unit. The effect of improving the dispersibility of the polycarbonate by the polyester (B-2) is impaired and the film-forming property is reduced.

The phosphorus compound used here may be an inorganic phosphorus compound or an organic phosphorus compound, such as phosphorous acid, phosphoric acid, pyrophosphoric acid, metaphosphoric acid and salts thereof.
Examples thereof include di- or tri-alkyl phosphines, di- or tri-aryl phosphines, mono- or di-alkyl phosphinic acids, mono- or di-aryl phosphinic acids, phosphites, phosphates, and polyphosphoric acid. Among them, phosphorous acid and phosphorous acid ester are preferred. Examples of the ester include lower alkyl (for example, methyl and ethyl) esters, phenyl ester, and glycol (for example, ethylene glycol) esters.

These phosphorus compounds may be contained during the production of polyester and / or polycarbonate, or may be added to and mixed with the composition during melt extrusion.

In the present invention, the polyester (C) having ethylene terephthalate as the main repeating unit used in the third layer (C) is a polyester having at least 80 mol% of ethylene terephthalate repeating units.

In this polyester, as a component which can be copolymerized as the third component, for example, as an acid component, aromatic dicarboxylic acids such as isophthalic acid, phthalic acid, 2,6-naphthalenedicarboxylic acid, adipic acid and azelaine. Examples of the acid component include aliphatic dicarboxylic acids such as sebacic acid and decanedicarboxylic acid, and alicyclic dicarboxylic acids such as 1,4-cyclohexanedicarboxylic acid. Examples of the alcohol component include diethylene glycol, 1,4-butanediol and 1,6 -An aliphatic diol such as hexanediol,
Examples thereof include alicyclic diols such as 1,4-cyclohexanedimethanol. These can be used alone or
More than one species can be used in combination.

Since this polyester (C) is superior in adhesiveness to the metal plate to the polymer of the second layer (B),
The three-layer film of the present invention has improved adhesiveness to a metal plate as compared with the two-layer film including the first layer (A) and the second layer (B).

Among these polyesters, polyethylene terephthalate or copolyethylene terephthalate obtained by copolymerizing 20 mol% or less of isophthalic acid is preferably used in order to improve the adhesiveness to the metal plate. In particular, copolyethylene terephthalate obtained by copolymerizing 3 to 20 mol% of isophthalic acid is preferable.

The melting point of these polyesters (C) is
The melting point of the polyester of the layer (A) and the melting point of the polymer of the second layer (B) are preferably the same or lower, and particularly preferably low. When this melting point is higher than that of the polyester of the first layer (A) and the polymer of the second layer (B), the effect of improving the adhesiveness to the metal plate becomes small.

This polyester (C) has an intrinsic viscosity of 0.5 to 5 measured at 35 ° C. in orthochlorophenol.
It is preferably 0.9, and particularly preferably 0.6 to 0.8.

This polyester can be produced in the same manner as the above-mentioned polyester having ethylene terephthalate as a main repeating unit, but it is preferable to use a Ge compound catalyst or a Ti compound catalyst in this case. Examples of the Ge compound include (a) amorphous germanium oxide, (b) fine crystalline germanium oxide, (iii) a solution of germanium oxide dissolved in glycol in the presence of an alkali metal or an alkaline earth metal or a compound thereof, (D) A solution obtained by dissolving germanium oxide in water is preferred.
Preferred examples of the Ti compound include titanium tetrabutoxide and titanium acetate.

In the unstretched film of the present invention, the polyester forming the first layer (A), the polycarbonate forming the second layer (B) or the composition of the polycarbonate and the polyester and / or the third layer (C) are formed. In the polyester to be used, if necessary, an antioxidant, a heat stabilizer,
Additives such as an ultraviolet absorber, a plasticizer, inorganic particles, organic particles, and an antistatic agent can be dispersed and blended.

Further, the unstretched film of the present invention improves handleability (winding property) in the film manufacturing process,
Fine particles having an average particle diameter of 2.5 μm or less are preferably contained in the polyester forming the first layer (A) and / or the polyester forming the third layer (C). It may also be contained in the polycarbonate or the composition of the polycarbonate and the polyester forming the second layer (B). The content of the fine particles is preferably 0.01 to 1% by weight with respect to 100% by weight of the polyester forming the first layer (A) and / or the third layer (C). When fine particles are contained in the second layer (B), the content of the polycarbonate is 100% by weight based on 100% by weight of the polycarbonate or the polycarbonate / polyester composition.
It is preferable that the content is 01 to 1% by weight.

The lubricant may be inorganic or organic, but is preferably inorganic. Examples of the inorganic lubricant include silica, alumina, titanium dioxide, calcium carbonate, barium sulfate and the like, and examples of the organic lubricant include cross-linked polystyrene particles,
Examples include crosslinked silicone resin particles. In any case, the average particle diameter is desirably 2.5 μm or less. When the average particle diameter of the lubricant exceeds 2.5 μm, coarse lubricant particles (for example, particles having a diameter of 10 μm or more) of a portion deformed by molding work have a starting point. And a pinhole may be formed or, in some cases, broken.

In particular, a preferable lubricant in terms of pinhole resistance is a monodisperse lubricant having an average particle size of 2.5 μm or less and a particle size ratio (major axis / minor axis) of 1.0 to 1.2. It is a lubricant. Examples of such a lubricant include spherical silica, spherical tin dioxide, spherical zirconium, and spherical crosslinked silicone resin particles.

The unstretched film of the present invention comprises a first layer (A) made of polyester and a second layer (B) made of polycarbonate or polycarbonate and polyester, which is laminated on the second layer (B). Further, it has a structure in which a third layer (C) made of polyester is laminated. With such a structure, the third layer (C) is laminated on the metal plate so as to be in contact with the metal plate, and the first layer (A)
If the can is made so that it contacts the contents of the metal can, protect the second layer (B), which has poor aroma retention (flavor), with the first layer (A), which has a good aroma retention (flavor). As a result, the aroma retaining property (flavor property) of the entire film is improved, the scent component of the contents of the metal can is not adsorbed on the film, and the flavor of the contents is not damaged by the odor of the film. Further, since the third layer (C), which has better adhesiveness to the metal plate than the second layer (B), contacts the metal plate, the adhesiveness of the film to the metal plate is improved.

The non-stretched film having such a three-layer structure can be obtained, for example, by separately melting the components constituting the respective layers, performing coextrusion, and laminating and fusing before solidification, and the components constituting the respective layers. Can be separately manufactured by melting and extruding to form a film, and laminating and fusing the three.

The unstretched film of the present invention has a total film thickness of 5 to 100 μm, particularly 10 to 75 μm,
The thickness ratio (A / B) of the first layer (A) and the second layer (B) is 1
It is preferably / 99 to 50/50. Thickness ratio (A
/ B) is more preferably 5/95 to 40/60, and particularly preferably 10/90 to 30/70. The thickness of the third layer (C) is preferably 0.5 to 10 μm, more preferably 1 to 5 μm. If the thickness is less than 0.5 μm, the adhesion to the metal plate is insufficient and the impact resistance tends to be lowered, while if it exceeds 10 μm, the thickness of the second layer becomes relatively thin and the impact resistance is lowered. easy.

Further, since the film of the present invention is a film which has not been stretched and which has not been stretched, the second layer (B) is a polycarbonate which is likely to cause film breakage during stretching.
Can be formed.

Further, since it is unstretched, it has good adhesiveness with a metal plate, for example, it enables adhesive strength at a low temperature of about 150 ° C., and further, deep drawability with large deformation is improved. To do.

As the metal plate to which the non-stretched film of the present invention is attached, particularly the metal plate for can making, tin, tin-free steel, aluminum and the like plates are suitable. For bonding the film to the metal plate, for example, the following (a),
The method (a) can be used.

(A) The metal plate is heated to a temperature higher than the softening temperature of the film, the film is bonded, and then cooled and adhered.

(A) An adhesive layer is primer-coated on a film in advance, and this surface is bonded to a metal plate. As the adhesive layer, a known resin adhesive, for example, an epoxy adhesive, an epoxy-ester adhesive, an alkyd adhesive, or the like can be used. When the unstretched film of the present invention is attached to a metal plate, the third layer (C) formed of polyester having good adhesiveness is located on the side in contact with the metal plate and is in contact with the contents of the metal can. The lamination is performed so that the first layer (A) made of polyester is located on the side. For example, when the film of the present invention is attached to the inside of a metal can, the third layer (C) is attached to the can.

Furthermore, in the non-stretched film of the present invention, if necessary, between the first layer (A) and the second layer (B),
Alternatively, another additional layer may be laminated between the second layer (B) and the third layer (C).

[0062]

EXAMPLES The present invention will be described in more detail with reference to the following Examples, which should not be construed as limiting the present invention. In the examples, “part” means “part by weight”. The measurement of the characteristic values of polyester and polycarbonate and the evaluation of the film were performed as follows.

(1) Intrinsic viscosity of polyester [η] Measured in orthochlorophenol at 35 ° C.

(2) Melting point (Tm) and glass transition temperature (Tg) of polyester Measured by DSC.

(3) Concentration of terminal carboxyl group of polyester In a mixed solvent of phenol: tetrachloroethane = 2: 3, using tetrabromophenol blue as an indicator, N
Titrate with a solution of aOH in benzyl alcohol.

(4) Viscosity average molecular weight (Mv) of polycarbonate It is calculated from the intrinsic viscosity ([η]) measured in a methylene chloride solution using the following Schnell formula.

[0067]

[Equation 1]

(5) Extrusion Moldability of Film The discharge state of the molten polymer is observed and evaluated according to the following criteria. ◎: Extremely stable extrusion molding possible without melt runout ○: Stable extrusion molding possible with almost no melt runout △: Extrusion molding possible with occasional melt runout ×: Melt runout Frequently occurs, making it impossible to perform substantially stable extrusion.

(6) Peel strength The same two films were electrolytically treated with chromic acid so that the layer whose peel strength was to be evaluated was on the outside (the side in contact with the metal plate) between two 210 μm thick steel plates. Overlaid on 285
At a pressure of 20 kg / cm ² with a hot press
By holding for 0 second, it was laminated with a steel plate. A test piece is prepared by cutting the laminated plate into a size having a width of 10 mm and a length of 50 mm. This test piece has one end 2
A release agent is attached to 0 mm in advance so that the laminate plate can be easily peeled off, and two steel plates are peeled in opposite directions at a portion of 20 mm on the side of the test piece to which the release agent is attached. Both ends of the peeled portion are fixed with a tensile tester, and the peel strength is measured at a pulling speed of 20 mm / min. (According to JIS K 6854).

(7) Low temperature impact resistance One film and one film were prepared in the same manner as described in (6).
A laminated plate is manufactured from steel sheets. After the production, the laminate was kept in water at 50 ° C. for 5 days, and then the laminated plate was kept at 5 ° C.
The impact deformation test is performed according to the method described in JIS K5400.

That is, a shooting die having a curvature radius of 5 mm is set on the upper surface of the laminated plate on which the film is not laminated, and a weight having a mass of 200 g is gravity dropped from the position of 20 cm in height onto the shooting die. At this time, a rubber plate having a thickness of 5 mm is provided below the laminate plate.

After this impact deformation test, one electrode was applied to the metal surface of the laminated plate on which the film was not laminated, and 1 was placed on the film surface of the other laminated plate at the position (convex portion) where the weight was dropped. % Cotton solution is applied, the other electrode is applied to the cotton, a voltage of 6 V is applied, and the current value at that time is measured. The smaller the current value (mA), the better the low-temperature impact resistance.

(8) Fragrance retaining property (flavoring property) The laminated plate is cut into a disk shape having a diameter of 150 m / m, deep drawing is performed in four steps using a drawing die and a punch, and a side seamless container having a diameter of 55 mm. To create.

A metal can having a film laminated on its inner surface was filled with a 20 ppm aqueous solution of d-limonene, left for 5 days, peeled off, cut into a size of 15 cm × 15 cm, and heat treated at 80 ° C. for 30 minutes. The amount of adsorbed d-limonene per 1 g of the film is quantified using gas chromatography. The smaller this value is, the better the fragrance retaining property (flavor property) is, and the evaluation is performed according to the following criteria. ◯: Adsorption amount equal to or smaller than polyethylene terephthalate laminate plate Δ: Adsorption amount slightly larger than polyethylene terephthalate laminate plate ×: Adsorption amount larger than polyethylene terephthalate laminate plate

(9) Deep drawing workability The laminate plate was cut into a disk shape having a diameter of 150 m / m, and deep drawing work was carried out in four steps using a drawing die and a punch to obtain a 50 m / m diameter and a 120 m / m depth. Create a sideless seamless container. This deep-drawn state is observed and evaluated according to the following criteria. ◯: The film is processed without any abnormality on both the inner and outer surfaces, and no whitening or breakage is observed on the film on the inside and outside of the can. Δ: Whitening or breakage is found on the top of the can on the film on the inside or outside of the can. X: Part of the film is broken on the inside and outside of the can

(10) Deep drawing workability 1% NaCl water was placed in a container prepared by deep drawing workability, an electrode was inserted, and a current value was measured when a voltage of 6 V was applied with the container as an anode. (This test is hereinafter abbreviated as ERV test), and evaluated according to the following criteria. ◯: Both the inner and outer surfaces were processed without any abnormality, and the current value was less than 0.1 mA in the ERV test. X: The inner and outer surfaces were not abnormal, but the current value was 0.
It is 1mA or more, and cracks are observed in the film when the current-carrying part is magnified and observed.

[Example 1] (Production of polyester (for first layer (A))) Copolyethylene terephthalate copolymerized with 12 mol% of isophthalic acid (intrinsic viscosity 0.64, using germanium dioxide catalyst,
Titanium dioxide having a particle size ratio of 1.1 and an average particle size of 0.3 μm was contained in an amount of 0.3% by weight) by a melt polymerization-solid phase polymerization method. This polyester had a melting point of 229 ° C. and a glass transition temperature of 73 ° C.

(Production of Polycarbonate (for Second Layer (B))) 216 parts of diphenyl carbonate, 228 parts of bisphenol A and di-Na salt of bisphenol A 0.05
Part was charged into a reaction vessel equipped with a stirrer and a vacuum distillation system having a nitrogen gas inlet, and the operation of introducing nitrogen gas after vacuum degassing at room temperature was repeated 3 times to replace the reaction system with nitrogen. Then, after heating and reacting at 190 ° C. for 30 minutes under normal pressure, the pressure is gradually reduced at the same temperature and 50 mmH after 60 minutes.
g. Further, the reaction temperature was raised from 190 ° C. to 290 ° C. over about 60 minutes, and at the same time, the degree of vacuum was changed from 50 mmHg to 1 mmHg or less. As the reaction proceeded, phenol generated by the reaction was distilled off. 40 under the same conditions
A minute reaction was carried out to obtain a polycarbonate having a viscosity average molecular weight (Mv) of 26000 and a terminal hydroxyl group temperature of 73 equivalents / 10 ⁶ g.

(Production of Polyester (for Third Layer (C))) Copolyethylene terephthalate copolymerized with 15 mol% of isophthalic acid (intrinsic viscosity 0.60, germanium dioxide catalyst used) by melt polymerization-solid phase polymerization method Obtained. This polyester has a melting point of 220 ° C. and a glass transition temperature of 7
3 ° C.

(Production of Laminated Film) The First Layer (A)
For the second layer, polycarbonate for the second layer (B) and polyester for the third layer (C) were simultaneously coextruded using a three-layer die and laminated in this order to obtain a three-layer unstretched film. In this case, the first layer (A) and the third layer
After drying, the polyester of layer (C) was melt extruded at a polymer temperature of about 280 ° C., and the polycarbonate of the second layer (B) was melt extruded at a polymer temperature of about 287 ° C. and cooled by a casting roller. The thickness of the obtained non-stretched film was such that the first layer (A) was 3 μm, the second layer (B) was 20 μm, and the third layer (C) was 3 μm.

The evaluation results are shown in Table 1, which shows that extrusion molding is possible, low-temperature impact resistance and aroma retention (flavor property) are excellent, especially adhesion to a metal plate, deep drawing The sex was markedly improved.

COMPARATIVE EXAMPLE 1 In Example 1, the first layer (A) was not laminated and only the second layer (B) and the third layer (C) were used (thickness of the second layer (B) is 23 μm, 3 μm of the third layer (C)). The evaluation results are as shown in Table 1,
The aroma retaining property (flavor property) deteriorated.

[Comparative Example 2] In Example 1, the third layer (C) was not laminated and only the first layer (A) and the second layer (B) were formed (thickness of the first layer (A) 3 μm, second layer (B)
Is 23 μm). The evaluation results are as shown in Table 1, and the adhesiveness with the metal plate decreased.

Comparative Example 3 The unstretched film obtained in Example 1 was longitudinally stretched 3.0 times at 130 ° C. and then laterally stretched 3.0 times at 135 ° C., but many breakages occurred and the film was substantially stretched. The stable stretching could not be performed.

[0085]

[Table 1]

Example 2 (Production of polyester (for first layer (A))) Polyethylene terephthalate (intrinsic viscosity 0.75, germanium dioxide catalyst used, particle size ratio 1.1, average particle size 0.3 μm) Titanium dioxide (0.2% by weight) was obtained by melt polymerization-solid phase polymerization method. This polyethylene terephthalate had a melting point of 255 ° C. and a glass transition temperature of 78 ° C.

(Production of Polycarbonate (for Second Layer (B))) 216 parts of diphenyl carbonate, 228 parts of bisphenol A and bisphenol A diNa salt 0.05
Part was charged into a reaction vessel equipped with a stirrer and a vacuum distillation system having a nitrogen gas inlet, and the operation of introducing nitrogen gas after vacuum degassing at room temperature was repeated 3 times to replace the reaction system with nitrogen. Then, after heating and reacting at 190 ° C. for 30 minutes under normal pressure, the pressure is gradually reduced at the same temperature and 50 mmH after 60 minutes.
g. Further, the reaction temperature was raised from 190 ° C. to 290 ° C. over about 60 minutes, and at the same time, the degree of vacuum was changed from 50 mmHg to 1 mmHg or less. As the reaction proceeded, phenol generated by the reaction was distilled off. 40 under the same conditions
A minute reaction was performed to obtain a polycarbonate having a viscosity average molecular weight (Mv) of 28,000 and a terminal hydroxyl group temperature of 48 equivalents / 10 ⁶ g.

(Production of Polycarbonate / Polyester Composition (for Second Layer (B))) Polycarbonate 70
% By weight and 30% by weight of a polyester mixture consisting of 60% by weight of polyethylene terephthalate and 40% by weight of polybutylene terephthalate are mixed, and 45 ppm (phosphorus concentration conversion) of phosphoric acid is added as a phosphorus compound to form the second layer (B). A polycarbonate / polyester composition was obtained. The melting point of this composition was 253 ° C.

Both the polyethylene terephthalate and the polybutylene terephthalate are melt-polymerized.
It was obtained by the solid-state polymerization method, and the former has an intrinsic viscosity of 0.
64, using a germanium dioxide catalyst, melting point 255 ℃,
It has a glass transition temperature of 78 ° C. and a terminal carboxyl group concentration of 15 equivalents / 10 ⁶ g. The latter has an intrinsic viscosity of 1.1, a germanium dioxide catalyst is used, a melting point of 223 ° C., a glass transition temperature of 3
The temperature was 2 ° C. and the terminal carboxyl group concentration was 10 equivalents / 10 ⁶ g.

(Production of Polyester (for Third Layer (C))) Copolyethylene terephthalate copolymerized with 7 mol% of isophthalic acid (intrinsic viscosity 0.62, germanium dioxide catalyst used) by melt polymerization-solid phase polymerization method. Obtained. This polyester has a melting point of 239 ° C. and a glass transition temperature of 76.
° C.

(Production of Laminated Film) Polyethylene terephthalate (for first layer (A)), polycarbonate / polyester composition (for second layer (B)) and copolymerized polyethylene terephthalate (for third layer (C)). Are each dried by a conventional method and supplied to each of the three extruders for forming a three-layer coextrusion laminated film, and polyethylene terephthalate has a polymer temperature of about 28
At 0 ° C., the polycarbonate / polyester composition had a polymer temperature of about 285 ° C., and the copolymerized polyethylene terephthalate had a polymer temperature of about 280 ° C., and melt extrusion was performed through a slit for coextrusion. The co-extruded film was cooled with a casting roller and taken off to produce an unstretched film laminated in the above order.

The thickness of the obtained non-stretched film was such that the first layer (A) was 5 μm, the second layer (B) was 20 μm, and the third layer (C) was 1 μm.

The evaluation results are shown in Table 2. Extrusion molding is possible, and low temperature impact resistance and aroma retention (flavor property) are excellent. In particular, adhesion to a metal plate and deep drawing The sex was markedly improved.

[Comparative Example 4] In Example 2, the first layer (A) was not laminated and only the second layer (B) and the third layer (C) were used (thickness of the second layer (B) is 25 μm, the second layer (B) is 1 μm).

The evaluation results are shown in Table 2, and the aroma retention (flavor) was deteriorated.

[Comparative Example 5] In Example 2, the third layer (C) was not laminated and only the first layer (A) and the second layer (B) were formed (thickness of the first layer (A) 5 μm, second layer (B)
Is 21 μm).

The evaluation results are shown in Table 2, and the adhesiveness with the metal plate was lowered.

Comparative Example 6 The unstretched film obtained in Example 2 was longitudinally stretched 3.0 times at 150 ° C., then laterally stretched 3.0 times at 150 ° C. and heat set at 180 ° C. A biaxially stretched film was obtained. However, the thickness of the obtained biaxially stretched film was 5 μm for the first layer (A) and 20 μm for the second layer (B).
The third layer (C) was adjusted to have a thickness of 1 μm.

The evaluation results are shown in Table 2, and the adhesiveness with the metal plate and the deep drawability were both poor.

[0100]

[Table 2]

[Examples 3 to 5] In Example 2, the polycarbonate used in Example 1 was used as the polycarbonate, and "Adeka Stab 2112" (trade name) manufactured by Asahi Denka Kogyo Co., Ltd. was used as the phosphorus compound. A non-stretched laminated film was produced under the same conditions as in Example 2 except that the amount shown in 3 (in terms of phosphoric acid) was added.

The evaluation results are as shown in Table 3, and particularly when the addition amount of the phosphorus compound was 20 to 100 ppm, particularly good extrusion moldability was obtained.

[0103]

[Table 3]

[Embodiments 6 to 9] In the second embodiment, the third embodiment
Table 4 shows the isophthalic acid copolymerization amount of the polyester for the layer (C).
Changed as shown in. The melting point of each polyester is shown in Table 4.
It was as shown in.

[0105]

[Table 4]

The evaluation results are shown in Table 5, and particularly good results were obtained in terms of adhesiveness (peeling strength) when the copolymerization amount of isophthalic acid was 3 to 20 mol%.

[0107]

[Table 5]

[Embodiments 10 to 13] In Embodiment 2,
The total thickness of the second layer (B) and the third layer (C) was 21 μm, and the thickness of the isophthalic acid-copolymerized polyethylene terephthalate layer of the third layer (C) was changed as shown in Table 6.

The evaluation results are shown in Table 6, and when the thickness of the third layer (C) is 0.5 to 10 μm (Examples 10 to 10).
13), particularly good results are obtained in terms of adhesiveness (peel strength), and in particular, in the case of 1 to 5 μm (Examples 11 and 1).
In 2), even better results were obtained.

[0110]

[Table 6]

[Example 14] In Example 1, a non-stretched film was produced under the same conditions as in Example 1 except that the third layer (C) was made of the same polymer as the first layer (A). .

The evaluation results are shown in Table 7, and good evaluation was obtained even if the first layer (A) and the third layer (C) had the same melting point.

[0113]

[Table 7]

[0114]

EFFECTS OF THE INVENTION According to the present invention, the impact resistance at a low temperature is excellent, and the fragrance retaining property (flavor property) and the film forming property (extrusion moldability) are excellent. It is possible to provide an unstretched film for laminating metal plates, which has improved adhesiveness and deep drawability.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yukihiko Minamihira 3-37-19 Oyama, Sagamihara City, Kanagawa Teijin Limited Sagamihara Research Center

Claims (7)

[Claims] 1. A first layer (A) composed of a polyester containing ethylene terephthalate as a main repeating unit, and a second layer containing a polycarbonate essentially consisting of a repeating unit represented by the following general formula (1) ( B) and a third layer (C) made of polyester having ethylene terephthalate as a main repeating unit on the second layer (B). Stretched film. Embedded image (Wherein R ¹ and R ² each represent a hydrogen atom, an alkyl group having 1 to 5 carbon atoms or a cycloalkyl group having 5 to 6 carbon atoms in a ring, and R ¹ and R ² represent a carbon atom to which they are bonded. May form a cycloalkyl group having 5 to 6 ring members together with R ³ and R ⁴ each represent an alkyl group having 1 to 5 carbon atoms, a phenyl group or a halogen atom, and m and n each represent 0, 1 or 2) 2. The second layer (B) comprises a composition of 55% by weight or more of polycarbonate and 45% by weight or less of polyester, and the polyester mainly contains ethylene terephthalate as a main repeating unit and / or butylene terephthalate. The unstretched film for laminating a metal plate according to claim 1, which is polyester as a repeating unit. 3. The non-stretched film for laminating metal plates according to claim 2, wherein the polycarbonate or the composition forming the second layer (B) contains 20 to 100 ppm of a phosphorus compound. 4. The total thickness of the film is 5 to 100 μm, and the thickness ratio (A / B) of the first layer (A) and the second layer (B).
Is 1/99 to 50/50, The unstretched film for metal plate lamination according to claim 1. 5. The thickness of the third layer (C) is 0.5 to 10 μm.
The unstretched film for laminating a metal plate according to claim 1 or 4. 6. The polyester constituting the third layer (C) contains polyethylene terephthalate or isophthalic acid in an amount of 3 to 2
The non-stretched film for metal plate lamination according to claim 1 or 5, which is a copolyethylene terephthalate copolymerized with 0 mol%. 7. The polyester constituting the third layer (C) has a melting point which is the same as or lower than the melting point of the composition of the first layer (A) and the composition of the second layer (B).
An unstretched film for laminating a metal plate according to 5 or 6.