JPH0694205B2 - Composite film - Google Patents

Description

TECHNICAL FIELD The present invention relates to a biaxially stretched polyester film having excellent antistatic properties and easy adhesion.

[Prior Art] Conventionally, as a method for imparting antistatic property and easy adhesion property,
The following methods have been known. That is, as a method of imparting antistatic properties, various surfactants such as polyethylene glycol and sodium dodecylbenzenesulfonate are mixed as disclosed in JP-A-52-47071 and JP-A-52-47069. Or a method of applying a thin coating, or a method of kneading or coating a vinyl resin having styrenesulfonic acid or a salt thereof as a constituent, as described in JP-A-49-73443. Further, as a method of imparting easy adhesion, a method of kneading various easy adhesion substances such as polyester copolymer, acrylic resin, and modified polyolefin resin, or as disclosed in JP-A-46-1123, acrylic This is a method of thinly applying an easy-adhesion layer of a resin, a polyester copolymer, a urethane resin, a polyvinyl alcohol resin, a modified polyolefin resin, an ethylene vinyl acetate copolymer, or the like.

[Problems to be Solved by the Invention] However, when various surfactants are used, the disadvantage is that the antistatic property is largely dependent on humidity and a stable effect cannot be obtained. On the other hand, styrenesulfonic acid or a salt thereof is used. When kneading a vinyl resin having a component as an antistatic property, the interface is peeled off by stretching due to insufficient affinity with polyester, resulting in voids and the disadvantage that transparency is significantly deteriorated. On the other hand, in the case of coating, similarly, there is a drawback that the coating strength, especially the resistance to chaffing, is insufficient because the affinity with polyester is not sufficient.

On the other hand, when various easily-adhesive substances were kneaded to such an extent that the adhesiveness was improved, there was a defect that mechanical properties were deteriorated, while when they were applied, there was a defect that the adhesiveness or the chafing resistance was insufficient. .

The present invention solves the above problems, antistatic property, adhesiveness,
An object is to provide a composite film having excellent coating film strength.

[Means for Solving Problems] The composite film of the present invention has a concentration of sulfonic acid or sulfonate in the surface layer of 0.002 to 100% by kneading sulfonic acid or sulfonate into polyester.
On at least one surface of the polyester film, which is 2.0%, the general formula (However, R is hydrogen or methyl group, M is hydrogen, alkali metal, alkaline earth or ammonium, R ₁ , R ₂ , R ₃ and R ₄ are each hydrogen, halogen, alkyl group or alkoxy group) 5% by weight of polymer as main constituent
It is characterized in that it is stretched after applying a layer containing 95% by weight or more.

The polyester in the present invention includes ethylene terephthalate, ethylene α, β-bis (2-chlorophenoxy) ethane-4,4′-dicarboxylate, ethylene α, β-bis (phenoxy) ethane-4,4′-dicarboxylate. And at least one structural unit selected from ethylene and 2,6-naphthalate units as main constituents.

Further, within the range that does not inhibit the present invention, preferably 10 mol%
Other components than the above may be copolymerized as long as they are within the above range.

The film of the present invention contains the above composition as a main component, but may be blended with various polymers within a range that does not impair the object of the present invention, and may also be an antioxidant, a heat stabilizer, a lubricant, an ultraviolet absorber, Inorganic or organic additives such as nucleating agents may be added to the extent that they are usually added.

In the present invention, the addition method of the sulfonic acid or its salt is not particularly limited, but it is preferably added in the form of a polymer, preferably in the form of a polymer having a weight average molecular weight of 1000 or more, more preferably in the form of a polymer having a weight average molecular weight of 10,000 or more. It is suitable. The polymer having sulfonic acid or its salt is not particularly limited, but as a typical one Copolymerized with acrylic acid, acrylic acid ester, methacrylic acid, methacrylic acid ester, or styrene in the form of A polymer consisting of only Polymers obtained by using as a part or all of the dicarboxylic acid of various polyesters can be mentioned.

But among them When the polymer introduced in the form of is used, it is considered that the compatibility with the polyester as the base polymer is insufficient, but the improvement effect is more remarkable, which is preferable.

However, -X is not particularly limited, and is H ⁺ , Na ⁺ , K ⁺ , -NH ₄
^+, -Li ^+, is a cationic ion such as -Ca ^++. Among them, from the viewpoint of thermal stability when mixed with polyester and extruded
NH ₄ ⁺ , Li ⁺ , Ca ⁺⁺ and K ⁺ are preferable, and Li ⁺ , K ⁺ and Ca ⁺⁺ are particularly preferable.

In the present invention, the concentration in the film surface layer is 0.002
It should be ~ 2.0%. Preferably 0.006-0.8%,
More preferably, it is 0.02 to 0.2%. If it is less than 0.002%, the coating strength is poor, while if it exceeds 2%, the characteristics of the base polyester are deteriorated.

The method in which the concentration in the film surface layer is within the range of the present invention is a simple film forming method, does not deteriorate the physical properties of the base polyester film, and the method of kneading from the viewpoint that the coating film toughness is excellent, particularly The method of kneading using the method described below is excellent. That is, the melt viscosity at the melt extrusion temperature of the substrate film is 1/2 or less of the substrate polyester, preferably 1/3 or less, more preferably 1/8.
A compound having a sulfonic acid or a sulfonate as shown below has a so-called compression ratio (ratio of the polymer filling amount in the feed part and the metalling part (cross-sectional area ratio)), which is a parameter indicating the degree of kneading in an extruder. Mixing with a predetermined polyester using an extruder that is 3.8 or more, the time from polymer injection to discharge from the die is 10 minutes or more, preferably 15 minutes or more and 120 minutes or less, and extrusion-molded on a cooling drum and then stretched It is preferable to heat-treat. The film thus obtained has a particularly high concentration of sulfonic acid or sulfonate in the surface layer as compared with the central portion of the film, so that the coating film toughness can be increased without deteriorating the characteristics of the substrate. This is preferable because it is possible.

However, the concentration of sulfonic acid or sulfonate in the present invention means S _2P for C _1S in the outermost layer 100 Å under the following measurement conditions using Shimadzu X-ray photoelectron spectroscopy ESCA750.
The relative intensity ratio of

-Measurement conditions-Excitation X-ray: MgKα _1,2 line (1253.6eV) X-ray output: 8kV, 30mA Temperature: 20 ° C Vacuum degree: 10 ^-5 Pa General formula in the present invention (However, R, M, R ₁ , R ₂ , R ₃ , and R ₄ are as described above.) A polymer having a repeating unit as a main constituent is a polymer sulfone containing a polymer having a different sulfone group introduction ratio. An acid salt or a polymeric sulfonic acid. Although there is no limitation on the introduction rate of the sulfo group, the introduction rate of 40 to 100 mol% is preferable from the viewpoint of the effect of improving conductivity and adhesiveness. More preferably 75 mol%
˜100 mol%, more preferably 90 mol% to 100 mol%. As a matter of course, a copolymer of the compound having the above general formula and styrene, methacrylic acid (ester), acrylic acid (ester), or fumaric acid (ester) is also included in the present invention. 40 mol% or more,
It is preferably 60% or more, more preferably 90% or more and 100% or less from the viewpoint of conductivity.

The weight average molecular weight is not particularly limited, but is preferably 10 to 5,000,000, more preferably 2000 to 1,000,000, and further preferably 10,000 to 500,000.

The coating layer provided on the base material has a general formula A polymer having the following repeating unit as a main constituent and a mixture with another resin are applied.

The resin to be mixed is not particularly limited, but it is preferable to mix it with a water-soluble or water-dispersible resin from the viewpoint that it can be applied in the form of an aqueous paint and the dispersibility. As the water-soluble or water-dispersible resin, a polyester resin, an acrylic resin, a polyamide resin, a urethane resin, a vinyl resin, a butadiene resin, an epoxy resin, a silicone resin, or a mixture thereof is thermoplastic. , And thermosetting properties can be used.

Methylol- or alkylol-based urea-based, melamine-based, acrylamide-based, polyamide-based resins and epoxies as cross-linking agents to improve the adhesion (blocking), water resistance, solvent resistance, and mechanical strength of the coating layer Compound, aziridine compound, blocked polyisocyanate,
A reactive compound such as a vinyl compound may be contained in the coating layer. The coating layer of the present invention, if necessary, an antifoaming agent,
Coatability improver, thickener, organic lubricant, inorganic fine particles,
An antioxidant, an ultraviolet absorber, a foaming agent, a dye, a pigment and the like may be contained.

To improve the coatability and adhesiveness of the coating agent to the film,
The film may be subjected to chemical treatment or electric discharge treatment before coating and stretching, but it is not particularly necessary in the present invention because the affinity with the base film is improved.

Polyurethane as water-soluble or water-dispersible resin,
It is preferable to use polyester or acrylic resin from the viewpoint of adhesiveness and transparency. Specific examples of suitable polyurethanes include those in which the polyurethane has at least one of a carboxylic acid group, a sulfonic acid group, and a sulfuric acid half ester base, and among them, an ammonium salt.

Specific examples of suitable polyurethanes include polyesters obtained by copolymerizing 5-sulfosodium isophthalic acid in an amount of 0.5 to 20 mol%. Among them, at least one of terephthalic acid, isophthalic acid and adipic acid is used as the acid component, and at least one of ethylene glycol or hexane glycol, 1,4-butanediol, diethylene glycol, neopentyl glycol and tetramethylene glycol is used as the alcohol component. When a polyester having a viscosity of 3 to 6 cps when diluted with 5% by weight is used, it is particularly preferable because not only the adhesion and antistatic properties but also the surface of the composite layer is smooth and the film gloss is excellent.

Examples of the acrylic resin include those containing an alkyl acrylate or an alkyl methacrylate as a main component, and 30 to 99.9 mol% of the component, and a vinyl monomer component 70 which is copolymerizable with these and has a functional group. ~ 0.
Water-soluble or water-dispersible resins containing 1 mol% are preferred.

The vinyl monomer copolymerizable with alkyl acrylate or alkyl methacrylate and having a functional group imparts hydrophilicity to the resin to improve the water dispersibility of the resin,
Alternatively, a resin and a polyester film, or those having a functional group that improves the adhesiveness between the resin and another coating layer provided on the undercoat layer are preferable, and the preferable functional group is a carboxyl group or a salt thereof, an acid anhydride group, or a sulfone An acid group, or a salt thereof, an amide group or an alkylol-amide group, an amino group (including a substituted amino group), an alkylol-amino group or a salt thereof, a hydroxyl group, an epoxy group and the like. Particularly preferred are a carboxyl group or a salt thereof, an acid anhydride group, an epoxy group and the like. Two or more kinds of these groups may be contained in the resin.

The reason why the alkyl acrylate or alkyl methacrylate in the acrylic resin is preferably 30 mol% or more is that the coating formability, the strength of the coating film, and the blocking resistance are improved. 99.9 mol% of alkyl acrylate or alkyl methacrylate in acrylic resin
It is preferable that the following is introduced by introducing a compound having a specific functional group as a copolymerization component into the acrylic resin to facilitate water solubilization and water dispersion and to stabilize the state for a long period of time. , Furthermore, the improvement of the adhesiveness between the coating layer and the polyester film layer, the strength of the coating layer due to the reaction in the coating layer, the improvement of the water resistance, the chemical resistance,
Further, it is possible to improve the adhesiveness between the film of the present invention and other materials.

Examples of the alkyl group of alkyl acrylate or alkyl methacrylate include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, t-butyl group, 2-ethylhexyl group, lauryl group, Examples thereof include stearyl group and cyclohexyl group.

As the vinyl-based monomer having a functional group copolymerizable with alkyl acrylate or alkyl methacrylate, the following compounds having a functional group such as a reactive functional group, a self-crosslinking functional group, a hydrophilic group can be used.

Examples of the compound having a carboxyl group or a salt thereof or an acid anhydride group include acrylic acid, methacrylic acid, itaconic acid, maleic acid, phthalic acid, crotonic acid, metal salts of these carboxylic acids with sodium, ammonium salts or Examples thereof include maleic anhydride.

Examples of the compound having a sulfonic acid group or a salt thereof include vinyl sulfonic acid, styrene sulfonic acid, metal salts of these sulfonic acids with sodium, ammonium salts and the like.

The compound having an amide group or an alkylolated amide group, acrylamide, methacrylamide, N-methylmethacrylamide, methylol acrylamide, methylol methacrylamide, ureido vinyl ether, β-ureido isobutyl vinyl ether,
Examples include ureidoethyl acrylate.

Examples of the compound having an amino group or an alkylolated amino group or a salt thereof include diethylaminoethyl vinyl ether, 2-aminoethyl vinyl ether, 3-aminopropyl vinyl ether, 2-aminobutyl vinyl ether, dimethylaminoethyl methacrylate and dimethylaminoethyl. Vinyl ethers, their amino groups being methylolated, alkyl halides,
Examples include quaternary chlorides such as dimethylsulfate and sultone.

Examples of the compound having a hydroxyl group include β-hydroxyethyl acrylate, β-hydroxyethyl methacrylate,
β-hydroxypropyl acrylate, β-hydroxypropyl methacrylate, β-hydroxy vinyl ether, 5-hydroxypentyl vinyl ether, 6-hydroxyhexyl vinyl ether, polyethylene glycol monoacrylate, polyethylene glycol monomethacrylate, polypropylene glycol monoacrylate,
Examples include polypropylene glycol monomethacrylate.

Examples of the compound having an epoxy group include glycidyl acrylate and glycidyl methacrylate.

In addition to the above compounds, the following compounds may be used in combination. That is, acrylonitrile, methacrylonitrile,
Styrenes, butyl vinyl ether, maleic acid mono- or dialkyl esters, fumaric acid mono- or dialkyl esters, itaconic acid mono- or dialkyl esters, methyl vinyl ketone, vinyl chloride, vinylidene chloride, vinyl acetate, vinylipyridine, vinylpyrrolidone, vinyltrimethoxysilane, etc. However, the present invention is not limited to these.

The acrylic resin may contain a surfactant, but the low molecular weight surfactant contained in the acrylic resin is condensed during the film formation process and accumulated at the particle-particle interface, or in the coating layer. There is a case where problems occur in the mechanical strength, water resistance, and adhesiveness with the laminate of the coating layer due to migration to the interface. In such a case, a so-called soap-free polymerized product containing no surfactant can be used.

However a copolymer of 35 / 65-65 / 35 (molar ratio) of methyl methacrylate and methyl acrylate among them the backbone polymer, -COOH, are each from 1 to 5 wt% introducing water dispersible acrylic and -CH ₂ OH It is particularly suitable.

In the coating layer of the present invention, as described above, the general formula 5% by weight of a polymer containing the repeating unit
It is necessary that the content is not less than 95% by weight. If it is less than 5% by weight, the effect of improving the adhesiveness and the antistatic property are insufficient, and if it is more than 95% by weight, the toughness of the coating film becomes poor, which is not preferable.
Particularly, when it is 10% by weight to 30% by weight, a good balance of adhesiveness, coating film toughness and antistatic property is obtained, which is preferable.

The thickness of the coating layer after stretching is not particularly limited, but usually 0.
It is 001 to 5 μm. It is preferably 0.01 to 0.4 μm, and more preferably 0.04 to 0.2 μm from the viewpoint of adhesiveness and antistatic property.

Further, if necessary, inorganic particles may be added to the coating layer, but representative examples thereof include the above-mentioned inorganic particles having an average particle size of 1 μm or less, more preferably 0.5 μm or less, and particularly preferably. The particle size is 0.2 μm or less, and specific examples thereof include kaolin, silica, silica sol, calcium carbonate, titanium oxide, barium salt, alumina, molybdenum sulfide, carbon black and zirconium, but are not limited thereto.

However, among them, the use of a swelling layered silicate is preferable from the viewpoint of slipperiness and coating film toughness. Examples of the layered silicate exhibiting swelling property include montmorillonite, vermiculite, hectorite, teniolite, tetrasilicic mica, etc., or synthetic teniolite, hectorite, tetrasilicic mica from the viewpoint of transparency. Is preferred.

Next, a typical manufacturing method of the present invention will be described, but the present invention is not limited to this.

First, after thoroughly drying polyester pellets containing a compound having a sulfonic acid or a sulfonate and other various additives as necessary, the pellets are fed to a known extruder, preferably a melt extruder having a compression ratio of 3.8 or more. An unstretched sheet is produced by melting and extruding into a sheet form from a slit die at a temperature not lower than the temperature at which the pellets melt and not lower than a temperature at which the polymer decomposes, and cooling and solidifying. The unstretched sheet or a film obtained by stretching the unstretched sheet 3 to 8 times at 80 to 105 ° C is provided with a predetermined coating layer, and then at 80 to 130 ° C. 6 times, 3 to 3 in the horizontal direction
Simultaneously biaxially stretched 6 times, and when a uniaxially stretched film is used, it is stretched 3 to 6 times in the transverse direction. If necessary, 15
Heat treatment is performed at 0 ° C to 250 ° C for 0.1 to 10 seconds while giving 0 to 10% relaxation.

If necessary, it may be stretched 1.1 to 1.7 times in the longitudinal direction again.

[Operation] In the present invention, the general formula on the polyester film in which the concentration of sulfonic acid or sulfonate in the surface layer is within the predetermined range Since a layer containing a polymer having a repeating unit as a main constituent is applied and then stretched, the affinity with the coating film is improved without deteriorating the characteristics of the base film, resulting in excellent coating film toughness. It was possible to obtain an easily adhesive and antistatic film.

[Evaluation Method of Properties and Effects] (1) Adhesion Force The obtained film was hand-rubbed 10 times to examine the adhesion state of the coating layer. Those that did not peel at all were rated as "A", those that peeled less than 5% were rated as "O", and those other than that were rated as "X".

(2) Transparency Using a SEP-H-2 type turbidimeter (manufactured by Nippon Seimitsu Optical Co., Ltd.) J
When the increase in haze value (%) determined based on IS-K-6714-58 is 20% or less compared to the case where no sulfonic acid (salt) compound is added, "○" is given, and when it is more than 20%, "happiness" is given. X ".

(3) Antistatic property Super insulation resistance meter MODEL-VE-40 (manufactured by Kawaguchi Electric Industry Co., Ltd.)
The surface resistivity was measured at 20 ° C. and 60% RH at an applied voltage of 100 V.

(4) Adhesiveness The following four kinds of coating agents a), b), c) and d) are individually coated on the coating layer surface of the biaxially stretched polyester film, dried or crosslinked, and then 10 times by hand. After the rubbing, a commercially available cellophane adhesive tape (manufactured by Nichiban Co., Ltd.) was adhered on and peeled in the 90 ° direction, and the peeled state of the coating layer after peeling was evaluated. Those that did not peel at all were marked with "⊚", those that hardly peeled were marked with "○", and the others were marked with "x". In addition,
The table below shows the evaluation results when the one with the worst adhesiveness was used among the four types of coating agents.

a) Ultraviolet curable ink (UV ink) ... FDO (black ink) manufactured by Toyo Ink Co., Ltd. was applied by a gravure coater to a thickness of about 5 μm, and treated at an irradiation output of 80 W / cm and an irradiation distance of 10 cm for 8 seconds.

b) Polyvinyl alcohol (PVA) having a degree of polymerization of 1500 and a degree of saponification of 90 mol% was dissolved in water and applied so that the coating film thickness after drying was 5 μm. After coating, it was dried at 130 ° C. for 2 minutes.

c) Cellulose acetate butyrate (CAB) having a degree of acetylation of 13% and a degree of butylation of 37% was dissolved in water and applied so that the thickness of the coating film after drying was 10 μm, and dried at 150 ° C. for 2 minutes.

d) Magnetic paint: About 2.5 μm in thickness after drying the following composition
It was applied and dried at 150 ° C. for 2 minutes.

・ Γ-Fe ₂ O ₃ powder 68 parts by weight ・ Carbon black 7 parts by weight ・ Vinyl chloride-vinyl acetate-vinyl alcohol copolymer
26 parts by weight Acrylonitrile-butadiene copolymer 5 parts by weight Polyisocyanate 2 parts by weight Methyl isobutyl ketone 75 parts by weight Toluene 75 parts by weight [Example] The present invention will be described with reference to the following examples and comparative examples. However, the present invention is not limited to these examples.

Examples 1 to 6 and Comparative Examples 1 to 3 In polyethylene terephthalate having an intrinsic viscosity of 0.61, 82 mol% of terephthalic acid and 8 mol% of isophthalic acid as acid components.
And 5-sulfoisophthalic acid sodium salt 10 mol%,
In addition, a resin (S _2P / C _1S in the resin surface layer is shown in the table) prepared by mixing various amounts of a polyester copolymer having a molecular weight of about 30,000 and using ethylene glycol as a diol component at 285 ° C. Was melted using a screw with a compression ratio of 3.8, and was extruded onto a cooling drum having a surface temperature of 50 ° C. At this time, the time from polymer injection to polymer discharge was 18 minutes. The film thus obtained was stretched 4 times in the longitudinal direction at 85 ° C., and the main component was a copolymer of methyl methacrylate and methyl acrylate in a ratio of 50:50.
2.5 carboxyl groups and 2.5 methylol groups as functional groups
Water-dispersible acrylic resin with a number average molecular weight of 500,000 introduced in mol%, and VERSA as sulfonated polystyrene with H ⁺ as X ⁺ ions of SO ₂ O ^- X ⁺ and a weight average molecular weight of about 70,000.
-TL72 (manufactured by Kanebo NSC Co., Ltd.) is applied by changing the solid content ratio (the ratio is shown in the table). The coated layer was dried and stretched 3.5 times in the transverse direction at 110 ° C., and then heat-treated at 215 ° C. while being relaxed by 5%.
The thickness of the film obtained at this time is 14 μm, and the thickness of the coating layer is
It was 0.07 μm.

As can be seen from the table, the adhesiveness, the balance between the adhesiveness and the transparency are excellent only when the content is within the range of the present invention.

Example 7 Sulfonated polystyrene (provided that it is in the form of sodium salt) was added as a compound to be mixed with polyethylene terephthalate. Film formation was evaluated in the same manner as in Example 1. It can be seen that similarly excellent transparency and adhesion are exhibited.

EFFECT OF THE INVENTION In the present invention, the concentration of sulfonic acid or sulfonate in the surface layer of the base polyester film is 0.002 to 2.0.
Since the content was set to wt%, the following excellent effects could be obtained.

(1) Adhesion to the substrate, especially resistance to chaffing was improved.

(2) It became a film showing excellent transparency.

(3) Shows excellent antistatic properties.

(4) Easy adhesion with ink and various binders was improved.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-61-204240 (JP, A) JP-A-59-111889 (JP, A)

Claims (1)

[Claims] 1. A general formula is provided on at least one surface of a polyester film having a surface layer having a concentration of sulfonic acid or sulfonate of 0.002 to 2.0% by kneading sulfonic acid or sulfonate into polyester. (Wherein R is hydrogen or methyl group, M is hydrogen, alkali metal, alkaline earth or ammonium, R ₁ , R ₂ , R ₃ and R ₄ are each hydrogen, halogen, alkyl group or alkoxy group) 5% by weight of polymer as main constituent
A composite film, which comprises applying a layer containing 95% by weight or more and then stretching.