JPH0912754A - Laminated film - Google Patents

Abstract

PURPOSE: To prepare a laminated film useful for magnetic cards, etc., by coating the surface of a polyester film with an aqueous coating solution containing a specific compound and an easily adhesive resin such as a polyester resin, drying the coated film, stretching the dried film and subsequently thermally treating the film to form an easily adhesive coating film. CONSTITUTION: This laminated film is produced by coating the surface of a polyester film with an aqueous coating solution containing a composition comprising 100 pts.wt. of at least one kind of easily adhesive resin selected from the group of a polyester resin, an acrylic resin and an acryl-modified polyester resin and having a secondary transition point of 20-100 deg.C and 2-50 pts.wt. of an oxorane group-having compound of the formula as main components, drying the coated film, stretching the dried film and subsequently thermally treating the film to form an easily adhesive 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, images that have an easy-adhesive coating film that has excellent adhesiveness to inks and paints, solvent resistance, and blocking resistance. The present invention relates to a laminated film useful as a material, a process 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 or 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. In addition, the film laminated with the conventional easily adhesive coating is
For example, at a temperature of 40 to 70 ° C., the coating film tends to be blocked, so that it is difficult to wind the film into a roll.

[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,
At least one kind of easily adhesive resin (A) having a secondary transition point of 20 to 100 ° C. selected from the group consisting of polyester resin, acrylic resin and acrylic modified polyester resin
After coating an aqueous coating liquid containing a composition containing 00 parts by weight and 2 to 50 parts by weight of a compound (B) having an oxirane group represented by the following formula (I) as a main component, drying and stretching, This is achieved by a laminated film provided with an easily adhesive coating formed by heat treatment.

[0006]

Embedded image

The present invention will be described in detail below.

[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.

Examples of the glycol component include 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, polyethylene terephthalate or polyethylene-2,6-naphthalate homopolymer is excellent in mechanical properties such as high Young's modulus and in 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, glycol component or the like in order to improve the adhesion between the polyester film and the easily-adhesive coating film. 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.

Such polyester can be prepared 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 an average particle size of 0.1 as a lubricant in order to improve the slip property of the film.
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 crosslinking 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
When the temperature is set to 70 ° C., the compound (B) having an oxirane group sufficiently reacts with the carboxyl group in the molecule of the polyester resin, the acrylic resin and / or the acrylic modified polyester resin, and the solvent resistance of the easily adhesive coating film. And blocking resistance are improved, which is preferable. The thickness of the polyester film is 1 to 300 μm, especially 3 to 3 after stretching.
It is preferably 260 μm.

[Easy-Adhesive Resin (A)] The easily-adhesive resin (A) in the present invention has at least one secondary transition point selected from the group consisting of polyester resins, acrylic resins and acrylic modified polyester resins having a secondary transition point of 20. ~ 100 ° C,
The resin is 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.

[Polyester Resin] The polyester resin is composed of a polyvalent carboxylic acid component and a polyvalent hydroxy component, and has a secondary transition point having a carboxyl group at the terminal and / or side chain of the polyester molecule and is water-based at 20 to 100 ° C. It is a possible copolyester.

Examples of the polyvalent carboxylic 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.

Further, in order to introduce a carboxyl group into the side chain of the polyester molecule, it is preferable to use a trivalent or higher polyvalent carboxylic acid component or a polyvalent hydroxy component having a carboxyl group as a copolymerization component.

The copolyester having a second-order transition point of 20 to 100 ° C. uses an aromatic dicarboxylic acid as a main component as a polyvalent carboxylic acid component, and a glycol component as a polyvalent hydroxy component having a second-order transition point as described above. It can be obtained by selecting such a range.

The polyester resin can be prepared by a conventional method, and it is preferable that the average molecular weight is 7,000 or more because the easily adhesive coating film has good stretchability.

[Acrylic Resin] An acrylic resin has a carboxyl group at the terminal and / or side chain of the polymer molecule,
It is an acrylic copolymer having a second-order transition point of 20 to 100 ° C. obtained by polymerizing an acrylic acid ester-based monomer as a main raw material.

Examples of the acrylic ester type monomer include, for example, 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. Particularly, acrylic acid or in order to introduce a carboxyl group into a side chain of a polymer molecule, or It is preferable to use methacrylic acid 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 acrylate component, methacrylate component, acrylic acid component, acrylamide component, 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 polymer molecule obtained by polymerizing the above-mentioned polyester resin with the above-mentioned acrylic acid ester-based monomer and / or acrylic acid-based monomer. Alternatively, the secondary transition point having a carboxyl group on the side chain is 20
It is a modified copolymer at -100 ° C. For example, it can be obtained by graft-polymerizing the above-mentioned acrylic acid ester-based monomer and / or acrylic acid-based monomer onto a polyester resin in an aqueous liquid using a radical initiator.
This modified copolymer may have a functional group on the side chain of the molecule. The average molecular weight of the modified copolymer is 8,
It is preferable that it is 000 to 200,000 because the easily adhesive coating film has good abrasion resistance.

The acrylic-modified polyester resin having a secondary transition point of 40 to 100 ° C. has a secondary transition point of 20 to 110.
With respect to the copolyester at ℃, a hard component such as methyl methacrylate or ethyl methacrylate and a soft component such as acrylate ester are added at such a ratio that the secondary transition point of the acrylic modified polyester resin is 40 to 100 ℃. It can be obtained by copolymerization.

Easy-adhesive resin (A) used in the present invention
Can be used alone or as a mixture of two or more resins selected from the above polyester resins, acrylic resins and acrylic modified polyester resins.

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

[Compound (B) Having an Oxirane Group] The compound (B) having an oxirane group in the present invention is
It is a compound having four oxirane groups in the molecule represented by the following formula (I).

[0035]

Embedded image

The oxirane group of the compound (B) having an oxirane group represented by the formula (I) is ring-opened by heating and is bonded to the carboxyl group of the easily adhesive resin (A) to form an easily adhesive coating film. It has excellent solvent resistance.

[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) having an oxirane group, preferably 4 to. It is prepared by applying an aqueous coating solution containing a composition containing 40 parts by weight as a main component, drying, stretching and then heat treatment.
When the compounding amount of the compound (B) having an oxirane group 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 is lowered.

The composition described above has an average particle size of 0.0 as a lubricant in order to improve the slipperiness of the easily adhesive coating film.
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 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 liquid] In the present invention, an easily adhesive coating film is applied using an aqueous coating liquid 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 according to 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 machine 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,
Crosslinking due to the reaction between the oxirane group of the compound having an oxirane group and the carboxyl group in the molecule of the polyester resin, acrylic resin and / or acryl-modified polyester resin is insufficient, and the solvent resistance of the easily adhesive coating film is insufficient. If the temperature exceeds 270 ° C., the base film may be thermally deteriorated and 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.

[0045]

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 Adhesiveness) A resist ink containing a terminal bisacrylic polyurethane oligomer, a photopolymerization initiator, a photosensitizer and a colorant is applied to the coating surface of the film to a thickness of 7 μm and cured by irradiating 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 the polyester film not coated with the coating film and the coated surface (evaluation sample) of the film coated with the coating film with a solvent-moistened cotton swab for 20 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 coated surface and the non-coated surface of a film having a width of 50 mm are put together under the conditions of 54 ° C. and a load of 57 kg / cm ² .
After holding for 9 hours, the peeling strength of the mating surfaces was set to 20
It was measured at 0 mm / min and evaluated as follows. A: Peel strength ≦ 8 g (good blocking resistance) B: 8 g <Peel strength ≦ 14 g (slightly good blocking resistance) C: 14 g <Peel strength (poor blocking resistance)

[Example 1] Polyethylene terephthalate having an intrinsic viscosity of 0.65 was melted and cast on a cooling drum to obtain an unstretched film. This unstretched film was heated to 91 ° C.
The film was heated to 1, and stretched 3.5 times in the machine direction to obtain a uniaxially stretched film. Next, on one side of the uniaxially stretched film, 90 mol% of 2,6-naphthalenedicarboxylic acid as a dicarboxylic acid component, 3 mol% of adipic acid, 3 mol of trimellitic acid and 4 mol% of 5-K sulfoisophthalic acid, and ethylene as a glycol component. 80 mol% glycol, 7 mol% 1,4-butanediol, and 13 mol% diethylene glycol
Copolyester (E-1, Tg:
52 ° C., average molecular weight: 18,770) 39 parts by weight, ethyl methacrylate component 84 mol%, ethyl acrylate component 5 mol%, acrylic acid component 3 mol%, glycidyl methacrylate component 3 mol%, 2-hydroxy acrylate 41 parts by weight of copolymer (A-1, Tg: 48 ° C., average molecular weight: 45,980) of 2 mol% of ethyl component and 3 mol% of N-methoxymethylacrylamide component, oxirane group represented by the formula (I). A 5% by weight aqueous coating solution of a composition consisting of 8 parts by weight of the compound (B-1) having 1 and 12 parts by weight of an ethylene oxide / propylene oxide / block copolymer (average molecular weight: 3,660) was applied by a gravure coater. Then, after drying at 102 ° C, the film was stretched 4.1 times in the transverse direction at 109 ° C and heat-treated at 227 ° C to give a total thickness of 75.
A laminated film having a thickness of 0.1 μm and a coating thickness of 0.11 μm was prepared. The characteristics of this laminated film are shown in Table 1.

[Examples 2 to 8] The same as Example 1 except that the compounding amount of the compound having an oxirane group, the kind and compounding amount of the easily adhesive resin, 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] A laminated film was obtained in the same manner as in Example 1 except that a compound having an oxirane group was not added as a coating film component. The characteristics of this laminated film are shown in Table 1.
Shown in

[0053]

[Table 1]

It should be noted that the type of easily adhesive resin shown in Table 1 is [A-
2] and [M-1] are the following copolymers. [A-2]: 53 mol% methyl methacrylate component, 27 mol% ethyl methacrylate component, 12 mol% methyl acrylate component, 4 mol% acrylic acid component, 2-acrylic acid
Copolymer of 2 mol% of hydroxyethyl component and 2 mol% of N-methoxymethylacrylamide component (Tg: 46
C., average molecular weight: 42,700) [M-1]: 79% by weight of methyl methacrylate, 10% by mole of ethyl acrylate, 3% by mole of methyl acrylate, 43% by weight of the copolymerized polyester of E-1 above. Four
Modified polymer (Tg: 47) obtained by polymerizing 57% by weight of an acrylic monomer of 2% by mole of 2-hydroxyethyl acrylate and 2% by mole of N-methoxymethylaquamide.
(° C, average molecular weight: 67,500) As is clear from Table 1, the laminated films of Examples 1 to 8 have an easily adhesive coating film having excellent adhesiveness, solvent resistance, and blocking resistance. Met.

[0055]

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. .

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. .

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI Technical display location B32B 27/18 B32B 27/18 Z 27/30 27/30 A 27/36 27/36 C08K 5 / 04 KJJ C08K 5/04 KJJ C08L 33/04 LHW C08L 33/04 LHW C09D 5/00 PPF C09D 5/00 PPF PPT PPT 167/00 PKX 167/00 PKX C09J 5/02 JGP C09J 5/02 JKP 33:00 67:00 B29L 9:00

Claims (2)

[Claims] 1. An easily-adhesive resin (A) 100 having a secondary transition point of 20 to 100 ° C. on at least one surface of a polyester film, and at least one kind selected from the group consisting of polyester resins, acrylic resins and acrylic modified polyester resins. After applying a water-based coating liquid containing a composition containing, by weight, and 2 to 50 parts by weight of a compound (B) having an oxirane group represented by the following formula (I) as a main component, drying and stretching, heat treatment A laminated film provided with an easily-adhesive coating film produced by Embedded image 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.