JP3375005B2 - Laminated polyester film - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laminated polyester film, and more particularly to a laminated polyester film excellent in transparency, easy adhesion and antistatic property.

[0002]

2. Description of the Related Art Biaxially oriented polyester films are magnetic recording materials, packaging materials, electrical insulating materials, various photographic applications, and graphic quartz because of their excellent mechanical properties, electrical properties, dimensional stability, transparency and heat resistance. It is used as a base film in many fields such as applications. However, on the other hand, 2
The axially oriented polyester film has drawbacks such as poor adhesiveness because the surface is highly crystallographically oriented and that it is easily charged with static electricity due to friction. Many proposals have been made in the past to improve this. For example, to impart adhesiveness, physical methods such as corona discharge treatment in various gas atmospheres, plasma treatment, and ultraviolet irradiation treatment, chemical treatment with alkali, trichloroacetic acid, amine, phenol, or the like, or a combination thereof is used. Although treatment methods and the like have been attempted, they all have drawbacks such as not being able to obtain sufficient adhesiveness and the treatment effect being weakened over time.

On the other hand, an easy-adhesion treatment by providing a primer layer on the surface of a polyester film has been actively performed in recent years, and in particular, a method (in-line coating method) of performing the primer treatment at a stretch in the polyester film manufacturing process. It is considered to be influential in terms of process simplification, manufacturing cost, environmental protection, etc. As a primer layer used for this purpose, an organic sulfonate group-containing polyester resin (Japanese Patent Laid-Open No. 58-1727) for the purpose of easy adhesion, a mixture of an organic sulfonate group-containing polyester resin and an anionic urethane resin (special Kaisho 58-78761
Issue bulletin). Further, a method of adding an antistatic agent for the purpose of imparting antistatic property (Japanese Patent Laid-Open No. 60-14152).
5) and a method of applying a styrene sulfonic acid copolymer (JP-A-61-204240).

[0004]

However, the above-mentioned conventional technique has the following problems. That is, when the sulfonate group-containing polyester is used as the easy-adhesion layer, there is no antistatic effect even if the desired adhesiveness is obtained, and dust during the process adheres during the process of forming the coating layer on the easy-adhesion layer. However, there is a drawback that an accurate coating layer cannot be obtained. Further, in the method of adding the antistatic agent, since the antistatic agent itself is composed of a kind of a surfactant, an antistatic effect can be obtained, but it is easy to bleed out on the surface to impart adhesiveness. The point is insufficient. Although styrene sulfonic acid copolymer has an excellent antistatic effect, hydrophilic groups are easily localized on the surface, which attracts water in the air and significantly reduces the adhesiveness under high humidity, or damps fountain solution. There is a drawback that sufficient adhesiveness cannot be obtained by the offset printing used. Further, it has a drawback that it itself has a poor stretch following property, and when applied to the in-line coating method, the transparency is lowered due to cracks in the coating film.

The present invention eliminates these drawbacks, and the transparency is not deteriorated even by the in-line coating method, and the adhesiveness,
A laminated polyester film having an excellent antistatic effect is provided.

[0006]

According to the present invention, a laminated film having an antistatic polymer having a crosslinkable functional group, an acrylic copolymer, and a melamine-based crosslinking agent as main components is provided on at least one surface of a polyester film. , The crosslinkable functionality
Antistatic polymer having alkylene oxide in the side chain
Is a polymer having a phosphoric acid group interposed therebetween, and the laminated film has a surface resistivity of 5 × 10 ¹² Ω / □ or less at 25 ° C. and a relative humidity of 65%, and has a contact angle with water. 5
The main point of the laminated polyester film is 0 ° or more.

The polyester of the polyester film referred to in the present invention is a general term for polymers having an ester bond as the main chain of the main chain, and preferred polyesters are polyethylene terephthalate and polyethylene-2,6-.
Among them are naphthalate and polybutylene terephthalate, and among these, polyethylene terephthalate (hereinafter polyethylene terephthalate is abbreviated as PET) is particularly preferable in view of quality and economy. Further, in an image receiving sheet for information recording, such as electrophotography, heat-sensitive recording, various printing applications in which heat acts on a substrate, polyethylene-2,6-naphthalate (hereinafter referred to as polyethylene-2) is excellent in heat resistance and rigidity. , 6-naphthalate is abbreviated as PEN) in terms of flatness after recording. PE
T is 80 mol% or more, preferably 90 mol% or more, which has ethylene terephthalate as a repeating unit, but a part of other dicarboxylic acid component and diol component may be copolymerized. In the PET, known additives such as a heat stabilizer, an oxidation stabilizer, a weather stabilizer, an ultraviolet absorber, an organic slippery agent, a pigment, a dye, an organic or inorganic agent are added within a range that does not impair the effects of the present invention. Fine particles, an antistatic agent, a nucleating agent, etc. may be added.

The intrinsic viscosity of the above-mentioned polyester (25 ° C.
(Measured in ortho-chlorophenol) of 0.40-1.
20 dl / g, preferably 0.50 to 0.80 dl / g
Those within the range are suitable for the content of the present invention.

The polyester film using the above-mentioned polyester is biaxially oriented in the state where the laminated film is provided, and the biaxially oriented polyester film means that the unstretched polyester sheet or film is elongated. About 2.5 to 5.0 times in each direction and width direction, and then heat treated at 150 to 250 ° C.,
It means that the crystal orientation has been completed and that it exhibits a biaxial orientation pattern in wide-angle X-ray diffraction.

The thickness of the polyester film is not particularly limited and is appropriately selected according to the application. In the present invention, the laminated film provided on at least one surface of the polyester film is 5 × 10 ¹² Ω / □ or less, preferably 1 × 10 ¹² Ω / □ or less, and more preferably 5 × 10 ¹¹ Ω / □ at 25 ° C. and 65% relative humidity. It has the following antistatic properties and has a contact angle with water of 50 degrees or more, preferably 60 degrees or more, and more preferably 70 degrees or more. Surface resistivity is 5 × 10 ¹² Ω /
If it exceeds □, the antistatic effect is small, and dust is likely to adhere to it during printing and other processes, resulting in a high possibility of printing defects. Further, when the contact angle with water is less than 50 degrees, the adhesion to various coatings such as a magnetic recording layer, an ultraviolet curable ink, and an oxidative polymerization type ink on the laminated film becomes insufficient. By providing a layer having a surface resistivity of a specific value or less and a contact angle of water of a specific value or more as in the present invention, it is possible to obtain a laminated polyester film having both antistatic properties and adhesive properties. is there.

It is usually difficult to obtain such a laminated film with an antistatic polymer such as a conventional surfactant which is likely to be deposited on the surface or does not have a reactive functional group. In the present invention, the antistatic polymer is crosslinked.
Of an antistatic polymer having a functional group with a side chain
Use the one that has a phosphate group via the xylene oxide
It is preferable that a monomer having a reactive functional group is copolymerized and has a molecular weight of 5,000 to 5,000.
About 500,000 is good . In particular, those containing alkylene oxide and a phosphoric acid group in the monomer constituting the resin are preferable, and a method of adding a cation after copolymerization with the other monomer described below or a method of adding a phosphoric acid group of a monomer having an alkylene oxide and a phosphoric acid group in advance. It can be obtained by making phosphating by the neutralization method into one component of the monomer. Among them, it is preferable that the alkylene oxide and the phosphate group are present in one monomer, and it is more preferable that the phosphate group is present after the polymerization by interposing the alkylene oxide in the side chain of the polymer. The alkylene oxide is represented by-(R-O) n- (R: alkyl group and derivatives thereof, n: integer of 1 to 9). Particularly preferred examples are those containing ethylene oxide, propylene oxide, and both ethylene oxide and propylene oxide. Examples of such monomers include acid phosphooxyethyl acrylate and acid phosphooxyethyl methacrylate.
, 3-chloro-2-acid phosphooxypropyl acrylate, 3-chloro-2-acid phosphooxypropyl methacrylate, acid phosphooxypropyl acrylate, acid phosphooxypropyl methacrylate, Acid phosphooxy (polyoxyethylene glycol) monoacrylate, acid phosphooxy (polyoxyethylene glycol) monomethacrylate
And acid phosphooxy (polyoxypropylene glycol) monoacrylate, acid phosphooxy (polyoxypropylene glycol) monomethacrylate and the like can be mentioned as typical examples. As the other monomer component constituting the antistatic polymer, known ones can be used. For example, alkyl acrylate, alkyl methacrylate (methyl group as the alkyl group,
(Ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, t-butyl group, 2-ethylhexyl group, lauryl group, stearyl group, cyclohexyl group, etc.) as a basic skeleton, and further a crosslinkable functional group Copolymerization with the following monomers for imparting purposes is important to meet the requirements of the invention. Examples of such a functional group include a carboxyl group, a methylol group, an acid anhydride group, a sulfonic acid group, an amide group or a methylolated amide group, an amino group (including a substituted amino group), or an alkyl group. Examples of the modified amino group, hydroxyl group, epoxy group and the like. Examples of the monomer having the above functional group include acrylic acid, methacrylic acid, itaconic acid, maleic acid, fumaric acid, crotonic acid, vinylsulfonic acid, styrenesulfonic acid, acrylamide, methacrylamide, N-methylmethacrylamide, and methylolation. Acrylamide, methylated methacrylamide, diethylaminoethyl vinyl ether, 2-aminoethyl vinyl ether, 3-
Aminopropyl vinyl ether, 2-aminobutyl vinyl ether, dimethylaminoethyl methacrylate, and those obtained by methylating the above amino groups, β-hydroxyethyl acrylate, β-hydroxyethyl methacrylate. Rate, β-hydroxypropyl acrylate, β-
Hydroxypropyl methacrylate, β-hydroxyvinyl ether, 5-hydroxypentyl vinyl ether, 6-hydroxyhexyl vinyl ether, polyethylene glycol monoacrylate, polyethylene glycol monomethacrylate, glycidyl Examples thereof include acrylate and glycidyl methacrylate, but are not limited thereto. Further, in addition to the above, the following compounds, for example, acrylonitrile, methacrylonitrile, styrenes, butyl vinyl ether, mono- or dialkyl esters of maleic acid and itaconic acid, methyl vinyl ketone, vinyl chloride, vinylidene chloride, vinyl acetate, vinyl pyridine. , Vinylpyrrolidone, and alkoxysilane having a vinyl group may be used as the copolymerization component. Among these, copolymerization of monomers having a carboxyl group and a methylol group is particularly preferable, and acrylic acid, methacrylic acid, N-methyl acrylamide and the like are preferably used.

The copolymerization ratio of the monomer having a crosslinkable functional group is not particularly limited, but is 1 to 30% by weight, preferably 3 to 20.
From the viewpoint of adhesiveness, it is preferable that the content is wt%.

The above alkylene oxide and phosphate group-containing monomer may be copolymerized with any other monomer at any ratio, but the above monomer is preferably 20% by weight or more, preferably 3%.
It is preferably 0% by weight or more, and more preferably 40% by weight or more in terms of antistatic property and transparency.

The phosphate group is arbitrarily selected as long as it is formed by the addition of a monovalent cation, but among them, lithium, sodium, potassium, rubidium and ammonium are preferable from the viewpoint of antistatic property, and further potassium or rubidium is preferable. Is particularly preferable in terms of antistatic property.

In the present invention , the antistatic function and contact with water are used.
In order to make the antenna feel specific, the antistatic polymer and
Main ingredient is a mixture of kuriru resin and melamine cross-linking agent
The basic structure is a laminated film made of coating material
Of. The acrylic resin used is preferably one having a crosslinkable functional group, like the above antistatic polymer, and one example of a particularly suitable acrylic resin is a carboxyl group, a hydroxyl group or a methylol group-containing acrylic monomer as a crosslinkable functional group. It is a copolymer and the glass transition point of the polymer is 0 to
It is preferably 45 ° C. and has a molecular weight of 10,000 or more.

The mixing ratio of the antistatic polymer and the acrylic resin is not particularly limited, but the preferred range is 10 to 70% by weight of the antistatic polymer in the laminated film,
Preferably 20 to 60%, more preferably 30 to 50%
Is.

Further, in the present invention, a melamine-based crosslinking agent is used in order to bring out the effect more remarkably . Particularly Arukiro - Ru effective der in that Le melamine resin to increase the contact angle with water. The amount of the melamine-based crosslinking agent added is preferably 1 to 40% by weight, preferably 3 to 20% by weight in the laminated film.

Since the antistatic polymer of the present invention and the other resin to be mixed are preferably dissolved or dispersed in water when applied to the in-line coat method, they are prepared by a method such as emulsion polymerization or suspension polymerization. Those which are dissolved or dispersed in water are preferable.

The thickness of the laminated film is not particularly limited, but in the present invention, it is 0.01 to 2.0 μm, preferably 0.04 to.
The thickness is preferably 1.0 μm, more preferably 0.06 to 0.5 μm.

In the present invention, the laminated film is produced by a method in which the crystal orientation of the polyester film as the base material is applied before the crystal orientation is completed, and then the film is stretched in at least one direction and then the crystal orientation of the PET film is completed. The preferred method is that the effects of the present invention can be more remarkably exhibited. That is, one or both sides of a base PET film which has not been stretched or has been stretched in the longitudinal direction is subjected to corona discharge treatment, and an aqueous resin preparation liquid is applied.
After that, while continuously gripping with clips, approximately 80 to 13
After being introduced into a hot air zone of 0 ° C and dried, or while being dried, stretched in the width direction, further introduced into a hot air zone of approximately 160 to 250 ° C, and heat treated for approximately 1 to 30 seconds to complete crystal orientation. It is a method to let. Further, after stretching in the width direction and before the heat treatment, stretching may be performed 1.1 to 1.8 times in the longitudinal direction.

In the laminated film of the present invention, known additives such as heat stabilizers, etc., within the range that does not impair the effects of the present invention,
Oxidation resistance stabilizers, weather resistance stabilizers, ultraviolet absorbers, organic lubricants, organic and inorganic fine particles may be added. Known thermoplasticity when adding organic or inorganic fine particles for the purpose of imparting slipperiness or blocking resistance to the laminated film,
Cross-linked organic particles and inorganic active and inactive particles can be used. Colloidal silica having an average particle diameter of 0.05 to 1 μm is particularly preferable.

As the coating method, a known coating method, for example, a reverse coating method, a gravure coating method, a rod coating method, a die coating method or the like can be used.

Next, an example of the method for producing the laminated polyester film of the present invention will be described, but the method is not limited to this.

Pellets of PET, which are substantially free of particles, are thoroughly vacuum dried and then fed to the extruder at about 280
Sheet is melt extruded at ℃, cooled and solidified to obtain unstretched P
Create an ET sheet. This sheet is stretched 2.5 to 5 times in the longitudinal direction with a roll heated to 80 to 120 ° C. to obtain a uniaxially oriented PET film. Corona discharge treatment is applied to one side of this film, and an aqueous dispersion of resin diluted to a predetermined concentration is applied. After coating, the end portion of the film is gripped by a clip and introduced into a hot air zone heated to 80 to 130 ° C. and stretched 2.5 to 5.0 times in the width direction. Continued 160 ℃ ~ 2
It is introduced into a heat treatment zone at 40 ° C. and heat treatment is performed for 1 to 10 seconds to complete the crystal orientation. In this heat treatment step, a relaxation treatment of 3 to 12% may be performed in the width direction or the longitudinal direction, if necessary.

The thus obtained laminated polyester film is excellent in transparency, easy adhesion and antistatic property, and can be suitably used for magnetic recording materials, photographic films, printing base films and the like.

[0026]

[Characteristic Measuring Method and Effect Evaluation Method] The characteristic measuring method and effect evaluating method in the present invention are as follows.

(1) Thickness of coating layer It was determined from a photograph of a cross section of the coating layer of the laminated film, which was observed using a transmission electron microscope HU-12 manufactured by Hitachi Ltd.
The thickness was an average value in the measurement visual field, and was an average value of 30 pieces.

(2) Surface specific resistance Digital ultra-high resistance in an atmosphere of 25 ° C. and 65% relative humidity /
It was measured using a micro ammeter R8340 (manufactured by Advantest Corporation).

(3) A contact angle meter CA-D type (manufactured by Kyowa Interface Science Co., Ltd.) was used for the laminated surface of the laminated polyester film stored for 24 hours in an atmosphere having a contact angle with water of 25 ° C. and a relative humidity of 50%. The contact angle was measured using distilled water stored under the same conditions. The measurement used the average value of 10 pieces. (4) Transparency Haze meter-SEP-according to JIS-K-6714
Measured at H-2.

(5) Adhesiveness-1 (Adhesion between base film and laminated film) 100 1mm ² crosscuts were put in the laminated film, and cellophane tape manufactured by Nichiban Co., Ltd. was stuck on it with a finger. After being strongly pressed, it was rapidly peeled off in the direction of 180 degrees, and the number of remaining pieces was judged according to the following criteria, and ◯ or more was evaluated as good.

⊚: 100/100 (remaining number / measured number) ◯: 80/100 or more Δ: less than 80/100 50/100 or more × less than 50/100 (6) Adhesiveness-2 (magnetic paint adhesiveness) -To CAD4301 (Dainichi Seika Kogyo Co., Ltd.)
(Made by Sumitomo Bayer Co., Ltd.) to 100 parts by weight, to prepare a paint having a solid content concentration of 20% by weight, which is applied using a bar coater at 100 ° C. 5
Dry for minutes. The adhesion was determined by the same method as in (5) above.

(7) Adhesiveness-3 (Adhesion of UV-curable ink) As a UV-curable ink, FLASH DRY (FDO
L ink (manufactured by Toyo Ink Mfg. Co., Ltd.)
The coating method was applied to the laminated film to a thickness of about 1.5 μm. After that, the ultraviolet rays with an irradiation intensity of 80 W / cm ² are applied at an irradiation distance of 9 cm for 8
It was irradiated and cured for 2 seconds. The adhesion was evaluated by the same method as in (5) above.

(8) Adhesiveness-4 (Adhesiveness of UV curable ink mixed with dampening water) Dampening water (water + isopropyl alcohol (10 wt%) against 100 parts by weight of the ultraviolet curable ink of (7) above. ) + Phosphoric acid adjusted to pH 5.5) 30 parts by weight,
After thoroughly kneading, printing was carried out in the same manner as in the above (7) to evaluate.

(9) Flatness of film The ultraviolet-curable ink laminate coated and cured in the above (7) is placed so that the flatness of the laminate is placed on the glass plate with the ink side facing up, and the flatness of the curl is set. The degree was visually measured and judged according to the following criteria.

[0035] ◎: Very flat with no curl ◯: Slight curl at the edge but good △: The curl extends to around the center ×: The curl is remarkable

[0036]

EXAMPLES Next, the present invention will be explained based on examples, but the present invention is not necessarily limited to these.

Example 1 PET essentially free of particles (intrinsic viscosity 0.65 dl
/ G) Pellets were sufficiently dried in vacuum and then fed to a heated extruder at 280 ° C. and extruded in a sheet form from a T-shaped die. The sheet was wound around a mirror-finished drum having a surface temperature of 50 ° C. and cooled and solidified to prepare an unstretched PET film. This PET film was stretched 3.5 times in the longitudinal direction while passing through a group of heating rolls at 95 ° C. to obtain a uniaxially oriented film. A corona discharge treatment was applied to one surface of this film, and the following aqueous dispersion was applied so that the laminated thickness would be 0.1 μm after completion of crystal orientation. After application, continuously heat the tape at 110 ° C while gripping the edges with clips.
Substrate, dried, preheated, stretched 4.0 times in the width direction, and further heat-treated at a heating zone of 200 ° C. for 3 seconds.
A laminated biaxially oriented PET film having an ET film thickness of 50 μm and a laminated thickness of 0.1 μm was obtained.

"Aqueous dispersion composition" (a) Emulsion polymerization of acid phosphooxyethyl methacrylate / butyl acrylate / acrylic acid neutralized in advance with potassium hydroxide in a ratio of 70/25/5 (% by weight). An aqueous dispersion of an antistatic polymer having a molecular weight of about 150,000 (b) acrylic emulsion (methyl methacrylate /
Butyl acrylate / acrylic acid (55/35/10)
(% By weight of copolymer) (c) Hexamethylolated melamine (a) / (b) / (c) in a solid content weight ratio of 35/55 /
It was mixed with 10 and further diluted with water to obtain a 3 wt% liquid. The results are shown in Table 1. This laminated polyester film was excellent in transparency, antistatic property and adhesiveness.

Examples 2 to 5 and Comparative Examples 1 to 3 A laminated polyester film was prepared in the same manner except that the compounding ratio of (a) / (b) / (c) in Example 1 was changed as shown in Table 1. It was created. The results are shown in Table 1.

Comparative Example 4 A laminated polyester film was prepared in the same manner as in Example 1 except that the Na salt of polystyrenesulfonic acid (molecular weight of about 50,000) was used in place of the water dispersion component (a) of Example 1. . The results are shown in Table 2.

[0041]

Example 6 A laminated polyester film was prepared in the same manner as in Example 1 except that PET was changed to PEN. The results are shown in Table 2.

Comparative Example 5 A laminated polyester film was prepared in the same manner as in Example 1 except that the aqueous dispersion component (a) was changed to Na dodecylbenzene sulfonate. The results are shown in Table 2.

Comparative Example 6 The procedure of Example 1 was repeated except that the aqueous dispersion (a) of Example 1 was replaced with an aqueous dispersion of an acrylic polymer prepared without neutralizing acid phosphooxyethyl methacrylate. A laminated polyester film was prepared. The results are shown in Table 2.

[0045]

[Table 1]

[Table 2]

[0046]

EFFECT OF THE INVENTION The laminated polyester film formed according to the present invention has both antistatic property and easy adhesion property and is excellent in transparency.

─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-6-313010 (JP, A) JP-A-3-243684 (JP, A) JP-A-57-645 (JP, A) JP-A-64- 65180 (JP, A) JP 5-216165 (JP, A) JP 2-291551 (JP, A) JP 5-279502 (JP, A) JP 64-1533 (JP, A) JP-A-3-255139 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) B32B 1/00-35/00 C08J 7/04

Claims (3)

(57) [Claims] On at least one surface according to claim 1 polyester film, laminated film antistatic polymer and an acrylic copolymer and a melamine crosslinking agent as a main component is provided having a crosslinkable functional group, a crosslinkable functional group Antistatic poly having
Have a phosphate group with an alkylene oxide in the side chain.
And a surface resistivity at 25 ° C. and a relative humidity of 65% of 5 × 10 ¹² Ω / □ or less and a contact angle with water of 50 ° or more. Characteristic laminated polyester film. 2. The laminated polyester film according to claim 1, wherein the polyester film is a polyethylene terephthalate film or a polyethylene-2,6-naphthalate film. 3. Having a crosslinkable functional group in a laminated film
Content of antistatic polymer is 10% by weight or more and 70% by weight or less
The laminated polyester film according to claim 1 or 2, wherein the laminated polyester film is below .