JP2000229394A - Easily adhesive polyester film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve adhesiveness to a ultraviolet curable resin, blocking resistance, and lubricity by forming an acryl-modified polyurethane having a specified acrylic resin component/polyurethane resin component weight ratio at least on one side of a polyester film in a specified application thickness. SOLUTION: At least on one side of a polyester film. an acryl-modified polyurethane having an acrylic resin component/polyurethane resin component weight ratio of 3/7-7/3 is formed to have an application thickness after drying of 0.1-2 μm. In the production of the acryl-modified polyurethane, for example, an acrylic compound is dispersed in an aqueous polyurethane, and they are reacted to obtain an aqueous dispersion. The production method of the adhesive polyester film includes, for example, a method in which the aqueous dispersion of the acryl-modified polyurethane is applied on the base polyester film, or a method in which the application is done in a process for producing a biaxially oriented polyester film.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an easily-adhesive polyester film, and more particularly, to a film having excellent adhesion to an ultraviolet-curable resin, and having excellent properties in blocking resistance and slipperiness. The present invention relates to an easily adhesive polyester film.

[0002]

2. Description of the Related Art Polyethylene terephthalate (PET)
Biaxially stretched polyester films represented by films have excellent properties such as transparency, dimensional stability, mechanical properties, electrical properties, and chemical resistance.
It is used in a wide range of fields such as electrical insulating materials, information recording materials, and various process papers. Polyester has the above excellent properties, but the film surface is highly crystallographically oriented, so it has poor adhesion to various paints, etc., and it is necessary to apply easy adhesion treatment to the film surface There are many.

[0003] Methods for imparting easy adhesion to a polyester film include, for example, corona treatment, plasma treatment, and flame treatment. However, these methods have a drawback that their performance deteriorates with time. Thus, as a method of improving such a defect, there is a method of chemically treating the film surface. However, there are problems such as toxicity of chemicals and environmental pollution due to vaporization of vapor. In addition, there is a method of imparting easy adhesion by applying an organic solvent-based coating agent, but problems such as safety and environmental pollution due to evaporation of the solvent, and defects on the coating surface due to adhesion of dust occur. There is a problem that it is easy to do. Therefore, a water-based coating agent composed of a polyurethane or copolyester resin is used, which is advantageous in terms of economy and safety, with little adhesion of dust in a clean environment, no risk of explosion and no environmental pollution. A method has been proposed.

On the other hand, in recent years, labels and graphic bases printed with a UV curable ink based on a polyester film have been widely used due to advantages such as simplicity of printing and quick drying. It is necessary to impart easy adhesion to the polyester film from the point of view,
Until now, there has been no easily adhesive polyester film having sufficient performance. Films coated with an acrylic resin or a polyurethane resin have been used as an easily adhesive polyester film for UV-curable inks, but acrylic resins have poor adhesion to ink, especially to shearing forces. Further, polyurethane has insufficient heat resistance and has a problem of blocking. Therefore, a method of improving heat resistance by crosslinking an aqueous polyurethane with an epoxy resin has been proposed. However, since the urethane resin is flexible, the slip property of the film is poor, and wrinkles occur when the film is wound. There is. In addition, an acrylic resin-based coating agent having good slipperiness has been proposed, but has a problem that its adhesive strength is lower than that of polyurethane.

[0005]

SUMMARY OF THE INVENTION In view of the above-mentioned circumstances, the present invention provides an easily adhesive polyester film having excellent adhesiveness to ultraviolet curable resin, excellent blocking resistance and excellent slipperiness. It is something to offer.

[0006]

Means for Solving the Problems The present inventors have conducted intensive studies to solve the above-mentioned problems, and as a result, have found that at least one side of a polyester film is coated with an aqueous coating agent of an acrylic-modified polyurethane having a specific composition. It has been found that by applying in a large amount, an easily-adhesive polyester film having excellent adhesion to an ultraviolet-curable resin, excellent blocking resistance and excellent slipperiness can be obtained, and has reached the present invention.

That is, the gist of the present invention is to provide an acrylic-modified polyurethane having a weight ratio of acrylic resin component / polyurethane resin component of 3/7 to 7/3 on at least one side of a polyester film, and a coating thickness after drying of 0. .1
ポ リ エ ス テ ル 2 μm in an easily adhesive polyester film.

[0008]

Next, the present invention will be described in detail. As the raw material polyester for the polyester film used in the present invention, PET obtained by polycondensation of terephthalic acid and ethylene glycol is preferable, but other dicarboxylic acids such as isophthalic acid, naphthalenedicarboxylic acid, adipic acid and sebacic acid are preferred. Ingredients, 1,4-
Other glycol components such as butanediol, neopentyl glycol, polytetramethylene glycol, and bisphenol A may be copolymerized, and two or more of these components may be used in combination. In addition, polybutylene terephthalate (PBT), polyethylene naphthalate (PEN), polycyclohexylene dimethylene terephthalate (PC
It can be used by blending with other polyesters such as T).

The acrylic-modified polyurethane used in the present invention needs to have an acrylic resin component / polyurethane resin component ratio of 3/7 to 7/3 by weight. If the amount of the acrylic resin component is less than the above ratio, the lubricity of the film surface is lost, and if the amount is more than the above ratio, the easy adhesion decreases.

The method for producing the acrylic-modified polyurethane in the present invention is obtained, for example, by dispersing an acrylic compound in an aqueous polyurethane and then reacting the same. Aqueous polyurethanes include, for example, anionic functional groups such as carboxylate and sulfonate and cationic functional groups such as quaternary ammonium salts in order to increase the affinity of polyurethane resin for water. What introduce | transduced the group is used. Among these functional groups, anionic functional groups are preferred in view of dispersibility in water and ease of reaction control during synthesis, and among them, carboxylate and sulfonate are particularly preferred.

As a method for introducing a carboxylic acid group into the polyurethane, for example, a compound containing a carboxylic acid group as a raw material polyhydroxy compound at the time of synthesizing the polyurethane, or a method of introducing a hydroxyl group-containing carboxylic acid group into an unreacted isocyanate group in the polyurethane. An acid or an amino group-containing carboxylic acid is reacted, and then the reaction product is neutralized by adding it to an aqueous alkali solution while stirring at a high speed.

As a method for introducing a sulfonate group into polyurethane, for example, a polyhydroxy compound,
Obtained by forming a polyurethane prepolymer from a polyisocyanate and a chain extender, and adding and reacting a compound containing an amino group, a hydroxyl group, a sulfonate group and the like which can react with a terminal isocyanate group. Can be. At that time, the synthesis reaction is preferably performed in an organic solvent, and then the solvent is preferably removed after adding water.

The polyhydroxy compound used as a raw material for polyurethane includes, for example, polyethylene glycol, polypropylene glycol, polyethylene propylene glycol, polytetramethylene glycol,
Hexamethylene glycol, tetramethylene glycol, 1,5-pentanediol, diethylene glycol, triethylene glycol, polycaprolactone, polyhexamethylene adipate, polyhexamethylene sebacate, polytetramethylene adipate, polytetramethylene sebacate, trimethylolpropane, Trimethylolethane, pentaerythritol, glycerin and the like can be mentioned.

Examples of the polyisocyanate compound used as a raw material for polyurethane include hexamethylene diisocyanate, diphenylmethane diisocyanate, tolylene diisocyanate, isophorone diisocyanate, an adduct of tolylene diisocyanate and trimethylolpropane, and hexamethylene diisocyanate and trimethylol. Ethane adducts and the like can be mentioned.

The acrylic component constituting the acrylic-modified polyurethane in the present invention includes, for example, an alkyl acrylate (where the alkyl group is methyl, ethyl,
n-propyl, n-butyl, isobutyl, t-butyl,
2-ethylhexyl, cyclohexyl, etc.), alkyl methacrylate, 2-hydroxyethyl acrylate,
Hydroxyl-containing compounds such as 2-hydroxyethyl methacrylate, 2-hydroxypropyl acrylate, 2-hydroxypropyl methacrylate, acrylamide, methacrylamide, N-methylmethacrylamide,
Amide group-containing compounds such as N-methylacrylamide, N-methylolacrylamide, N-methylolmethacrylamide, N, N-dimethylolacrylamide, N-methoxymethylacrylamide, N-methoxymethylmethacrylamide, and N-phenylacrylamide; N
And amino group-containing compounds such as -diethylaminoethyl acrylate and N, N-diethylaminoethyl methacrylate; epoxy group-containing compounds such as glycidyl acrylate and glycidyl methacrylate; and salts thereof (sodium salt, potassium salt, ammonium salt). In addition, the above acrylic component can be used alone, but two or more compounds can be used.

As a method for producing the acrylic-modified polyurethane in the present invention, for example, a small amount of a dispersant and a polymerization initiator are added to an aqueous dispersion of an aqueous polyurethane, the temperature is maintained at a constant temperature, and the above-mentioned acrylic compound is stirred. The mixture is gradually added, and then, if necessary, the temperature is raised, and the mixture is reacted for a certain period of time to obtain an aqueous dispersion.

The coating thickness of the acrylic-modified polyurethane after drying is preferably 0.1 to 2 μm, more preferably 0.1 to 2 μm.
5 to 1.5 μm. When the coating thickness is less than 0.1 μm, the adhesiveness to the ultraviolet curable resin is insufficient, and even when the coating thickness is larger than 2 μm, no further improvement in performance is observed, and the cost increases, which is not preferable. .

As a method for producing a polyester film in the present invention, for example, a raw material polymer is melt-extruded, quenched and solidified to form an unstretched film, and then biaxially stretched in the machine and transverse directions, followed by heat fixing and relaxation treatment. It can be obtained by applying.

The method for producing the easily adhesive polyester film of the present invention includes, for example, a method of applying an aqueous dispersion of an acryl-modified aqueous polyurethane to a base polyester film so as to have a predetermined thickness, or a method of preparing biaxially stretched polyester. Applied during the film manufacturing process,
It can also be manufactured by a so-called in-line coating method. As a method of applying the aqueous dispersion, a known coating method can be applied. For example, a gravure roll method, a spray method, a roll coater method, or the like can be used. The law is suitable. Further, it is desirable that the base polyester film is previously subjected to a physical treatment such as a corona treatment or a chemical treatment in order to improve the adhesiveness with the easily adhesive layer.

[0020]

Next, the present invention will be described in detail with reference to examples. The evaluation method used in the examples is as follows.

(1) Adhesion between the easy-adhesion layer and the polyester film A cellophane tape (L-Pack LP-24, manufactured by Nichiban Co., Ltd.) is pressed and attached to the easy-adhesion layer of the polyester film, and then pulled vigorously in the 180 ° direction. After peeling (peeling off the cellophane tape), the adhesion was evaluated as follows from the degree of holding the adhesive force of the cellophane tape. ：: The adhesive strength of the cellophane tape is maintained. Δ: The adhesive strength of the cellophane tape was partially impaired. ×: The adhesive strength of the cellophane tape is completely impaired.

(2) Blocking Resistance The easily adhesive polyester film was cut into a square of 10 cm × 10 cm, and 15 sheets of the film were piled up and pressed at 40 ° C. for 24 hours under a load of 10 kg. evaluated. ：: There is no blocking and there is no catch when peeling. Δ: There is a little catch when peeling. ×: Strongly caught when peeled, damage is seen on the surface of the easily adhesive layer.

(3) Cloudiness (%) of Film Film was measured using a haze meter (TC-H.DPK, manufactured by Tokyo Denshoku Co., Ltd.).

(4) Adhesiveness of UV-curable ink The UV-curable ink is applied to the easy-adhesion layer of the polyester film using a RI tester (manufactured by Meisho Seisakusho) so that the thickness after drying becomes about 3 μm, and irradiation is performed. Device (80W / cm,
One-light type; UV irradiation device HB-80101BY manufactured by Ushio Inc.)
UV irradiation at a speed of 10 m / min at
Dry at room temperature for 24 hours or more. As the ultraviolet curable ink, flash dry FDS-2 [Red] (manufactured by Toyo Ink Mfg. Co., Ltd.) was mixed with a FD reducer (manufactured by Toyo Ink Mfg. Co., Ltd.) as a diluent. (4-1) Cross cut cellophane tape peeling test On the ink-coated surface of a film with dimensions of 10 mm x 10 mm,
Cut 100mm squares at 1mm intervals, make 100 squares, peel off the regular cellophane tape, check the number of squares remaining without peeling the ink, and evaluate it according to the following evaluation criteria. went. (Evaluation criteria) 1. Less than 10 remaining squares 2. The number of remaining squares is 10 or more and less than 50. 3. 50 or more and less than 90 remaining squares 4. The number of remaining squares is 90 or more and less than 95. (4-2) Scratch resistance (scratch resistance) Scratches the ink-coated surface several times with a fingernail, examines the surface condition of the ink-coated surface at that time, and evaluates according to the following evaluation criteria did. (Evaluation criteria) ：: The scratched portion does not peel off at all. Δ: Part of the scratched part peeled off. ×: The scratched portion is completely peeled off.

(5) Dynamic friction coefficient (μk) Measured by an autograph manufactured by Shimadzu Corporation in accordance with ASTM D-1894. In general, the lower the value, the better the slipperiness of the film and the easier the handling.

(6) Comprehensive Evaluation The above evaluations were combined, and a four-step evaluation was performed according to the following evaluation criteria. ◎: good ○: no problem level ×: there is a problem XX: there is a problem

Examples 1-4, Comparative Examples 1-2 Polyurethanes containing carboxylate (Neoletz R-9409, manufactured by Zeneca) as aqueous polyurethanes, and copolymers having the copolymer composition shown in Table 1 as acrylic components were used. An aqueous solution of an acrylic-modified polyurethane having a solid content of 40 wt%, obtained by synthesis using
An ET film (Emblet, manufactured by Unitika) was coated with a wire bar coater and heat-treated at 140 ° C. for 15 seconds to obtain a film having a coating thickness of 1 μm and having an easily adhesive layer. Table 1 shows the performance of the obtained easily adhesive polyester film.

Comparative Example 3 An easily adhesive polyester film was obtained in the same manner as in Example 1 except that the coating thickness of the easily adhesive layer was changed to 0.05 μm. Table 1 shows the performance of the obtained film.

Comparative Example 4 An easily adhesive polyester film was obtained in the same manner as in Example 1 except that an aqueous polyurethane was used instead of the acrylic-modified polyurethane. Table 1 shows the performance of the obtained film.
It was shown to.

Comparative Example 5 An easily adhesive polyester film was obtained in the same manner as in Example 1 except that an acrylic resin having the composition shown in Table 1 was used instead of the acrylic-modified polyurethane. Table 1 shows the performance of the obtained film.

As is clear from Table 1, by using the acrylic resin component / polyurethane resin component in the acrylic-modified polyurethane having a weight ratio and a coating thickness within the range of the present invention, the adhesiveness to the ultraviolet curable ink, An easily-adhesive polyester film that satisfies both blocking resistance and slipperiness can be obtained.

[0032]

[Table 1]

[0033]

The easily adhesive polyester film of the present invention has excellent adhesiveness to an ultraviolet-curable resin and is excellent in blocking resistance, slipperiness, and transparency. It can be suitably used for photographic subbing materials, graphic applications, and the like.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C08L 75/04 C08L 75/04 // B29C 55/12 B29C 55/12 B29K 33:04 67:00 75: 00 B29L 7:00 9:00 (72) Inventor Nobuhiro Tanaka 31-3 Uji Hinojiri, Uji-shi, Kyoto Unitika Inside Uji Plastic Factory (72) Inventor Ryo Sugisaki 31-Uji-Hinojiri, Uji-shi, Kyoto 3 Unitika Co., Ltd. Uji Plastic Factory F-term (reference) 4F006 AA35 AB24 AB37 BA01 CA01 4F100 AK25B AK25C AK41 AK41A AK51B AK51C AL06B AL06C BA02 BA03 BA06 BA07 BA10B BA10C BA25 EH46 EH462 EJ38 AJ11 GBA JB EJ42 YJAJB GB10 AG01 AG03 QC05 QG01 QW50 4J002 BG04X BG05X BG07X CD19X CK02W GH00

Claims (1)

[Claims] 1. An acrylic modified polyurethane having an acrylic resin component / polyurethane resin component weight ratio of 3/7 to 7/3 on at least one side of a polyester film, and a coating thickness after drying of 0.1 to 2 μm. Adhesive polyester film provided as described above.