JPH0911427A - Laminated film - Google Patents

Abstract

PURPOSE: To obtain excellent solvent resistance, blocking resistance and ink bondability by a method wherein an aqueous coating liquid containing a specified easily bondable resin and a composition mainly made of a compound having a specified amount or more of an oxazoline group in a molecule is applied on one side of a polyester film and then the resultant film is dried, stretched and heat-treated so as to provide an easily bondable coating film. CONSTITUTION: On at least one side of a polyester film, an aqueous coating liquid containing a composition mainly made of 100 pts.wt. easily bondable resin consisting of an acrylic resin having the secondary transition point of 20-100 deg.C and/or an acrylic modified polyester resin having the secondary transition point of 20-100 deg.C and a compound having two or more of oxazoline groups in a molecule is applied by means of a method such as a gravure coating method or the like. After the application of the aqueous coating liquid, the resultant film is stretched and, when necessary, further re-stretched longitudinally or laterally and heat-treated at 150-270 deg.C so as to obtain the coated easily bondable coating film.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laminated film, and more particularly to at least one side of a polyester film,
Magnetic cards, magnetic tapes, magnetic disks, graphic materials, electronic materials, membrane films, printer ribbons, processes that have an easily adherent coating film that has excellent adhesion to inks and paints, solvent resistance, and blocking resistance. The present invention relates to a laminated film useful as a material, a packaging material and the like.

[0002]

2. Description of the Related Art Polyester films, especially those made of polyethylene terephthalate or polyethylene naphthalate, are widely used for magnetic recording materials such as magnetic tapes and general industrial materials such as packaging materials, photographic materials and graphic materials. ing.

Since such polyester film has poor adhesion to inks and paints, a method is usually adopted in which an easily adhesive coating film is laminated on the surface and inks and paints are adhered onto this coating film. ing. However, conventional easily-adhesive coating films have poor solvent resistance, and therefore have the drawbacks that the coating films are dissolved or swelled by the solvent used in the ink or paint. Many coatings have been proposed in order to improve such drawbacks. For example, an easily-adhesive coating film applied by using a coating liquid containing a crosslinking agent such as a melamine compound, an epoxy compound and a methylol compound is known. However, since a coating liquid containing such a cross-linking agent is difficult to use as an aqueous coating liquid, there are problems in disaster prevention and environmental protection, and the quality of the coating liquid deteriorates in a short time during storage as a coating liquid. There is a problem such as. Further, a film having a conventional easy-adhesive coating film laminated thereon has a drawback that it is difficult to wind the film into a roll because the coating film easily blocks at a temperature of 40 to 70 ° C., for example.

[0004]

SUMMARY OF THE INVENTION It is an object of the present invention to solve the problems of the prior art, improve solvent resistance and blocking resistance, and provide a laminated film having excellent adhesiveness.

[0005]

The object of the present invention is, according to the invention, to at least one side of a polyester film,
100 parts by weight of an easily adhesive resin (A) composed of an acrylic resin having a second-order transition point of 20 to 100 ° C. and / or an acrylic-modified polyester resin having a second-order transition point of 20 to 100 ° C. and two or more in the molecule. Compound having oxazoline group (B)
It is achieved by a laminated film provided with an easily-adhesive coating film prepared by applying an aqueous coating solution containing a composition having 2 to 50 parts by weight as a main component, drying, stretching, and then heat treatment. . Hereinafter, the present invention will be described in detail.

[Base Film] In the present invention, a polyester film is used as the base film, and the polyester constituting the base film is a linear polyester composed of a dicarboxylic acid component and a glycol component.

Examples of the dicarboxylic acid component include terephthalic acid, isophthalic acid, 2,6-naphthalenedicarboxylic acid, hexahydroterephthalic acid, 4,4'-diphenyldicarboxylic acid, adipic acid, sebacic acid and dodecanedicarboxylic acid. Among them, terephthalic acid and 2,6-naphthalenedicarboxylic acid are particularly preferable.

As the glycol component, for example, ethylene glycol, diethylene glycol, propylene glycol, 1,3-propanediol, 1,4-butanediol, neopentyl glycol, 1,6-hexanediol, cyclohexanedimethanol, polyethylene glycol. And the like, and ethylene glycol is particularly preferable.

Among such polyesters, a homopolymer of polyethylene terephthalate or polyethylene-2,6-naphthalate has excellent mechanical properties such as a high Young's modulus and excellent thermal properties such as good heat resistance and dimensional stability. It is preferable because an excellent film can be obtained.

The above-mentioned polyester may be a polyester obtained by copolymerizing the above-mentioned dicarboxylic acid component or glycol component in order to improve the adhesion between the polyester film and the easily adhesive coating. Further, a polyester obtained by copolymerizing a trifunctional or higher polyvalent compound in a small amount within a range in which the polyester is substantially linear (for example, 5 mol% or less) may be used.

The polyester can be produced by a conventional method. Also, the intrinsic viscosity of polyester is 0.50.
The above is preferable because mechanical properties such as high rigidity of the film are improved.

The above polyester has a mean particle size of 0.1 as a lubricant in order to make the film slippery.
It is preferable to add organic or inorganic fine particles of about 01 to 20 μm at a blending ratio of, for example, 0.005 to 20% by weight. Specific examples of such fine particles include inorganic fine particles such as silica, alumina, calcium carbonate, titanium oxide, barium sulfate, kaolin, and carbon black, silicone resin, melamine resin, polystyrene resin, crosslinked polystyrene resin, acrylic resin, crosslinked acrylic resin, etc. The organic fine particles and the like can be preferably mentioned.

In addition to the above-mentioned fine particles, an antioxidant, an antistatic agent, a colorant, a pigment, a fluorescent whitening agent, a cross-linking agent, an ultraviolet absorber and the like can be added if necessary.

The polyester film used in the present invention is
It can be manufactured by a conventionally known method. For example, the polyester is melted and cast on a cooling drum to obtain an unstretched film, and then the unstretched film is stretched in the machine direction by 2 to 7 times, and then in the transverse direction by 1.1 to 8 times. Can be manufactured. If necessary, the vertical direction and /
Alternatively, it can be stretched again in the transverse direction. Further, it is possible to complete the oriented crystallization by heat treatment after stretching. The stretching temperature is preferably higher than the second-order transition point (Tg) of polyester. Further, the heat treatment temperature is 150 to 2
The temperature of 70 ° C. is set to a compound having an oxazoline group and a functional group (for example, a carboxyl group (-C) in the molecule of the acrylic resin and / or the acrylic modified polyester resin.
OOH), a carboxyl base (-COOM, M: a quaternary amine salt, etc.) sufficiently react, and the solvent resistance and blocking resistance of the easily-adhesive coating film are favorable, which is preferable. still,
The thickness of the polyester film is 2 to 300 μ after stretching.
m, particularly preferably 4 to 260 μm.

[Easy-Adhesive Resin (A)] The easily-adhesive resin (A) in the present invention has a secondary transition point of 20 to 10 composed of an acrylic resin and / or an acrylic modified polyester resin.
It is a resin at 0 ° C, preferably 40 to 90 ° C. If the second-order transition point is less than 20 ° C, the blocking resistance of the easily adhesive coating will be poor, and if it exceeds 100 ° C, the easily adhesive coating will have insufficient abrasion resistance.

[Acrylic Resin] An acrylic resin is an acrylic copolymer having a second-order transition point of 20 to 100 ° C., which is obtained by polymerizing an acrylic acid ester monomer as a main raw material.

Examples of the acrylic ester type monomer include methyl methacrylate, ethyl methacrylate,
Examples thereof include butyl methacrylate, methyl acrylate, ethyl acrylate, butyl acrylate, ethyl crotonic acid, glycidyl methacrylate, 2-hydroxyethyl acrylate, 2-ethylhexyl acrylate, and the like.

This acrylic copolymer comprises at least one of the above acrylic acid ester monomers and acrylamide, methacrylamide, acrylic acid, methacrylic acid, sodium acrylate, potassium methacrylate, ammonium acrylate, N- It may be a copolymer obtained by polymerizing an acrylic acid-based monomer such as methylol acrylamide or N-methoxymethyl acrylamide. In particular, in order to introduce a carboxyl (salt) group into a side chain of a polymer molecule, acrylic It is preferable to use acid, methacrylic acid or ammonium acrylate as a copolymerization component.

In addition to the above, monomers such as vinyl chloride, vinyl acetate, styrene, vinyl ether, butadiene, isoprene, and sodium vinyl sulfonate can be used as a copolymerization component in the acrylic copolymer.

The acrylic copolymer includes an acrylate component, a methacrylate component, an acrylic acid component, an acrylamide component, a 2-hydroxyethyl acrylate component,
It is preferable that a hydrophilic component such as an N-methylol acrylamide component be contained as a copolymerization component because the dispersibility and solubility in the aqueous coating solution will be good. Further, it may be a copolymer having a functional group in the side chain of the molecule.

An acrylic copolymer having a second-order transition point of 20 to 100 ° C. uses a hard component such as methyl methacrylate or ethyl methacrylate as a main component and an acrylic ester such as acrylate ester as a copolymerization component. It can be obtained by copolymerizing the soft component at a ratio such that the second-order transition point is within the above range. Further, the secondary transition point of the acrylic copolymer can be adjusted by using a component having a methylol group, a methoxymethyl group or the like as a copolymerization component and crosslinking these groups.

The average molecular weight of the acrylic copolymer is 4.0
It is preferably from 0 to 1,000,000 because the easily adhesive coating has good abrasion resistance.

[Acrylic-modified polyester resin] The acrylic-modified polyester resin is a terminal and / or side of a polymer molecule obtained by polymerizing the above-mentioned acrylic acid ester monomer and / or acrylic acid monomer with a polyester resin. The secondary transition point having a carboxyl (salt) group in the chain is 20
It is a modified copolymer at -100 ° C. This polyester resin is a water-based copolymerizable polyester composed of a polycarboxylic acid component and a polyhydroxy component.

Examples of the polycarboxylic acid component include terephthalic acid, isophthalic acid, 2,6-naphthalenedicarboxylic acid, hexahydroterephthalic acid, 4.4'-diphenyldicarboxylic acid, adipic acid, sebacic acid and dodecanedicarboxylic acid. , Trimellitic acid, trimesic acid, pyromellitic acid, 5-Na sulfoisophthalic acid and the like. Examples of the polyhydric hydroxy component include ethylene glycol, diethylene glycol, propylene glycol, 1,3-propanediol, 1,4-
Examples include butanediol, neopentyl glycol, 1,6-hexanediol, cyclohexanedimethanol, polyethylene glycol, glycerin, trimethylolpropane, pentaerythritol, and dimethylolpropionic acid.

The polyvalent carboxylic acid component or polyvalent hydroxy component may be a dicarboxylic acid compound having one or more functional groups in the molecule, or a glycol compound.

The acrylic modified polyester resin having a second-order transition point of 20 to 100 ° C. has, for example, a Tg of 15 to 120 ° C. containing a hydrophilic component such as a sulfonate formed from a dicarboxylic acid component and a glycol component, and an average molecular weight of 3, 000-3
It is possible to obtain a modified copolymer by graft-polymerizing the above-mentioned acrylic acid ester-based monomer and / or acrylic acid-based monomer with a radical initiator in 0000 copolymerized polyester in an aqueous liquid. it can. This modified copolymer may have a functional group on the side chain of the molecule. The modified copolymer has an average molecular weight of 8,000 to 2
It is preferable that it is 0,000 because the easily adhesive coating film has good abrasion resistance.

Easy-adhesive resin (A) used in the present invention
The above acrylic resin or acrylic modified polyester resin can be used alone or in combination.

The easy-adhesive resin (A) may be a polyester resin, a polyurethane resin, an epoxy resin other than the above-mentioned easy-adhesive resin (A) in order to adjust the adhesiveness of the easy-adhesive coating film. A small amount (10% by weight or less) of resin, vinyl resin, polyether resin, water-soluble resin or the like may be added.

[Compound (B) Having Two or More Oxazoline Groups in the Molecule] The compound (B) having two or more oxazoline groups in the molecule of the present invention (hereinafter abbreviated as "compound (B)"). Is a low-molecular or high-molecular compound represented by the following general formula (I).

[0030]

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In the above formula (I), -R is a direct or polyvalent organic group (a polyvalent aliphatic hydrocarbon group having 1 to 12 carbon atoms, an alicyclic hydrocarbon group or an aromatic hydrocarbon group). And n is an integer of 1 to 10. Examples of the compound (B) are shown in the following formulas (I-1) to (I-4).

[0032]

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[0033]

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[0034]

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[0035]

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In the above formula (I-4), R ¹ , R ² and R ³ are hydrogen elements or an alkyl group having 1 to 5 carbon atoms, R ⁴ is a direct bond,
1 carbon atom containing a hydrocarbon group having 1 to 20 carbon atoms (aliphatic hydrocarbon group, alicyclic hydrocarbon group or aromatic hydrocarbon group) or a group represented by the following formulas (II-1) to (II-4) To 20 hydrocarbon groups.

[0037]

[Chemical 6]

As an example of the compound (B), 34 mol% of the unit represented by the following formula (I-5) and the following formula (I-6)
A copolymer having a unit of 66 mol% can be mentioned.

[0039]

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[0040]

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[Easy-adhesive coating film] The easily-adhesive coating film in the present invention comprises 100 parts by weight of the easily adhesive resin (A) and 2 to 50 parts by weight of the compound (B), preferably 3 to 40 parts by weight. It is prepared by applying an aqueous coating liquid containing a composition containing as a main component, drying, stretching, and then heat treatment. When the compounding amount of the compound (B) is less than 2 parts by weight, the solvent resistance of the easily adhesive coating film is insufficient, and when it exceeds 50 parts by weight, the adhesiveness decreases.

The above composition has an average particle size of 0.0 as a lubricant in order to improve the slipperiness of the easily adhesive coating.
Inorganic or organic fine particles having a size of about 1 to 20 μm are used, for example,
It can be contained in a blending ratio of 001 to 5% by weight. Specific examples of such fine particles include silica, alumina,
Inorganic fine particles such as titanium oxide, carbon black, kaolin, and calcium carbonate, organic fine particles such as polystyrene resin, crosslinked polystyrene resin, acrylic resin, crosslinked acrylic resin, melamine resin particles, silicone resin, fluororesin, urea resin, and benzoguanamine resin are preferable. Can be mentioned. The organic fine particles may be a thermoplastic resin or a thermosetting resin as long as they are resins capable of maintaining the state of fine particles in the coating film, and are crosslinked with a degree of crosslinking according to the purpose. It may be a resin.

In addition to the above-mentioned fine particles, surfactants, antioxidants, colorants, pigments, optical brighteners, plasticizers, other crosslinking agents,
Organic lubricants (slipping agents), ultraviolet absorbers, antistatic agents and the like can be added as required.

[Aqueous Coating Solution] In the present invention, an easily adhesive coating film is applied using an aqueous coating solution containing the above composition.
The solid content concentration of the aqueous coating liquid is preferably 1 to 30% by weight, and particularly preferably 2 to 20% by weight. When the solid content concentration is within this range, the viscosity of the aqueous coating liquid becomes suitable for coating. The aqueous coating liquid used in the present invention can be used in any form such as an aqueous solution, an aqueous dispersion, and an emulsion. Further, the aqueous coating liquid may contain a small amount of solvent.

[Coating of Coating Film] In the present invention, the easily adhesive coating film is coated by coating the above-mentioned aqueous coating solution on at least one side of the polyester film, drying and stretching, and then heat treating. As the coating method of the aqueous coating liquid, any known coating method can be applied, for example, a gravure coating method, a reverse roll coating method, a die coating method, a kiss coating method, a reverse kiss coating method, an offset gravure coating method, a Meyer bar coating method. The roll brush method, spray coating method, air knife coating method, impregnation method, curtain coating method and the like can be applied alone or in combination. The WET coating amount of the aqueous coating liquid is preferably 1 to 40 g, particularly ^{2 to 20} g per 1 m ² of the running film. It is preferable that the coating amount is in this range because drying becomes easy and coating unevenness hardly occurs.

The film to which the aqueous coating solution is applied in the present invention is
Stretchable polyester film, for example, unstretched film obtained by heat-melting polyester to form a film as it is; uniaxially stretched unstretched film in either longitudinal direction (longitudinal direction) or transverse direction (width direction) Stretched film; biaxially stretched film obtained by sequentially stretching a uniaxially stretched film in the longitudinal direction or the transverse direction in the transverse direction or in the longitudinal direction (which can be further stretched), or simultaneously stretching an unstretched film in both the longitudinal and transverse directions. A biaxially stretched film (which can be stretched further) can be mentioned.

The easily-adhesive coating film can be applied by applying an aqueous coating solution, drying it, stretching it, and if necessary, re-stretching it in the longitudinal or transverse direction and heat-treating it. The heat treatment temperature is preferably 150 to 270 ° C, particularly 180 to 250 ° C. When the heat treatment temperature is less than 150 ° C,
A functional group (for example, a carboxyl group (—COOH)) or a carboxyl group (—COO) in the molecule of the compound (B) and the acrylic resin and / or the acrylic modified polyester resin.
M, M: quaternary amine salt), etc.) may cause insufficient cross-linking, resulting in insufficient solvent resistance of the easily-adhesive coating film. If the temperature exceeds 270 ° C., the base film deteriorates due to heat. , The film characteristics may be deteriorated.

The thickness of the easily adhesive coating film is 0.01 to 1 μm.
m, particularly preferably 0.02 to 0.6 μm.
If the coating film thickness is less than 0.01 μm, the adhesiveness may be insufficient, and if it exceeds 1 μm, the coating film surface may be roughened or easily scraped.

[0049]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to examples. Each characteristic value was measured by the following method. The average molecular weight in the examples means a number average molecular weight.

1. Adhesiveness (ink adhesion) 6 μm of resist ink containing terminal bisacrylic polyurethane oligomer, photopolymerization initiator, photosensitizer and colorant is applied on the coating surface of the film and cured by irradiation with ultraviolet rays. I made an ink film. Then, a cellophane tape was attached to this coated surface, and after adhering with a roller, the cellophane tape was peeled off at a speed of 300 mm / min, and the adhesiveness was evaluated from the peeling condition as follows. A: Peeling occurred between the cellophane tape and the ink film. (Good adhesion) B: The ink film was peeled off in a state of partial cohesive failure. (Slightly good adhesiveness) C: Peeled between the film and the ink film. (Poor adhesion)

2. Solvent resistance Rubbing the surface (blank sample) of a polyester film not coated with a coating film and the coated surface (evaluation sample) of a film coated with a coating film with a cotton swab moistened with a solvent for 10 seconds, After wiping, the coated surface was dyed and the degree of coloring was compared and observed, and the solvent resistance of the evaluation sample was evaluated as follows. A mixed solvent of methyl ethyl ketone, toluene and cyclohexanone was used as the solvent. A: The coloring degree was almost the same as that of the blank sample. (Good solvent resistance) B: Colored slightly lighter than the blank sample.
(Slightly good solvent resistance) C: The coating layer dissolves and is not colored. (Poor solvent resistance)

3. Blocking resistance The coating surface and the non-coating surface of a film having a width of 50 mm are put together under the conditions of 56 ° C. and a load of 54 kg / cm ² .
After holding for 11 hours, peel strength of the mating surface
It was measured at 00 mm / min and evaluated as follows. A: Peel strength ≤ 7 g (good blocking resistance) B: 7 g <Peel strength ≤ 12 g (some blocking resistance) C: 12 g <Peel strength (poor blocking resistance)

[Example 1] Polyethylene terephthalate having an intrinsic viscosity of 0.63 was melted and cast on a cooling drum to obtain an unstretched film. The unstretched film was heated to 91 ° C.
The film was heated to 1, and stretched 3.6 times in the machine direction to obtain a uniaxially stretched film. Next, on one side of this uniaxially stretched film, a methyl methacrylate component of 34 mol% and an ethyl methacrylate component of 3
7 mol%, 14 mol% ethyl acrylate component, 3 mol% acrylic acid component, 7 mol% glycidyl methacrylate component, 2 mol% 2-hydroxyethyl acrylate component and 3 mol% N-methoxymethyl acrylamide component 52 parts by weight of combined polymer (acrylic resin, A-1, Tg: 51 ° C., average molecular weight: 36,400), 82 mol% of terephthalic acid as a dicarboxylic acid component, 9 mol% of isophthalic acid, 3 mol% of adipic acid, 5-K Sulfoisophthalic acid 5 mol%
And a copolymerized polyester obtained by using 1 mol% of trimellitic acid, 81 mol% of ethylene glycol as a glycol component, 7 mol% of 1,4-butanediol and 12 mol% of neopentyl glycol (average molecular weight: 18,2
30) 49 mol% of methyl methacrylate 24 mol%, ethyl methacrylate 56 mol%, ethyl acrylate 14 mol%, acrylic acid 1 mol%, 2-hydroxyethyl acrylate 3 mol% and N-methoxymethyl acrylamide 2 mol % Graft-polymerized (51% by weight) copolymer (acrylic modified polyester resin, E-1, Tg: 53
28 ° C., average molecular weight: 36,400), 9 parts by weight of the compound (B-1) of the formula (1-1), and ethylene oxide / propylene oxide / block copolymer (average molecular weight: 7,440) 11 A 5% by weight aqueous coating solution of a composition of 1 part by weight was applied with a gravure coater. Then, after drying at 102 ° C., the film was stretched 3.9 times in the transverse direction at 109 ° C. and further heat-treated at 235 ° C. to form a laminated film having a total thickness of 76 μm and a coating film thickness of 0.12 μm. The characteristics of this laminated film are shown in Table 1.

[Examples 2 to 8] The same as Example 1 except that the types and blending amounts of the acrylic resin, the acrylic modified polyester resin and the compound (B), and the thickness of the coating film were changed as shown in Table 1. To obtain a laminated film. The properties of these laminated films are shown in Table 1.

Comparative Example 1 A polyester film was obtained in the same manner as in Example 1 except that no coating film was applied. Table 1 shows the characteristics of this film.

[Comparative Example 2] Compound (B) as a coating film component
A laminated film was obtained in the same manner as in Example 1 except that was not added. The characteristics of this laminated film are shown in Table 1.

[0057]

[Table 1]

In the types of acrylic resin and compound (B) in Table 1, (A2), (B2) and (B3) are the following copolymers or compounds. [A2]: 56 mol% methyl methacrylate component, 27 mol% ethyl methacrylate component, 4 mol% acrylic acid component, 9 mol% glycidyl methacrylate component, 2 mol% 2-hydroxyethyl acrylate component and N-methoxymethyl Copolymer of 2 mol% of aquamid component (Tg: 52
° C, average molecular weight: 22,700) [B2]: compound represented by the above formula (I-2) [B3]: unit represented by the above formula (I-5) 34 mol% and the above formula (I-6). Copolymer of 66 mol% unit (average molecular weight: 2,760) As is clear from Table 1, the laminated films of Examples 1 to 8 have excellent adhesiveness, solvent resistance and blocking resistance. It had an adhesive coating.

[0059]

INDUSTRIAL APPLICABILITY In the present invention, since a cross-linking agent having a specific structure is used in the easily adhesive coating film component, it is possible to provide a laminated film excellent in ink adhesion, solvent resistance and blocking resistance. . In particular, the coating liquid used for applying the easily adhesive coating in the present invention can be used as an aqueous coating liquid, and has good stability when stored as an aqueous coating liquid, so that it is safe and economical. Can be used.

The laminated film of the present invention is useful for a membrane film, an electronic material, a graphic material, a magnetic card, a magnetic tape, a magnetic disk and the like. A membrane film structure can be made by printing a resist ink containing a photopolymerization initiator, a photosensitizer, and a colorant on bisacrylic polyurethane oligomer, bisacrylic vinyl polymer, etc., and irradiating and curing the resist ink. .

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Claims (2)

[Claims] 1. An acrylic resin having a secondary transition point of 20 to 100 ° C. and / or at least one surface of a polyester film.
Alternatively, 100 parts by weight of an easily adhesive resin (A) made of an acrylic-modified polyester resin having a second-order transition point of 20 to 100 ° C. and 2 to 50 parts by weight of a compound (B) having two or more oxazoline groups in the molecule. A laminated film provided with an easily-adhesive coating film prepared by applying an aqueous coating solution containing a composition containing as a main component, drying, stretching, and then heat treatment. 2. The laminated film according to claim 1, wherein the easily-adhesive coating film is formed by applying an aqueous coating solution, drying and stretching, and then heat treating at 150 to 270 ° C.