JP2007111964A - Polyester film for transfer material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polyester film which makes a transfer layer be transferred smoothly to an object to be transferred and is suitable for a transfer material. <P>SOLUTION: The polyester film for the transfer material has a mold release layer on one side. The usual peeling force of the mold release layer is 2,000 mN/cm or below. A fluorine-containing resin is preferably one of components constituting the mold release layer, and the central surface average roughness (SRa) of the surface of the mold release layer is preferably 0.020 μm or below. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a polyester film that can be suitably used for a transfer material.

  Generally, a transfer material is formed by sequentially laminating transfer layers such as a design layer and an adhesive layer on one surface of a plastic base film. Depending on the purpose, a hard coat layer and a metal vapor deposition layer are also laminated as a transfer layer.

  As a transfer method of these transfer materials, a transfer device is used to transfer to a transfer object with a heating roll, so-called hot stamping method, or an adhesive layer is in contact with a mold resin of an injection molding machine or a blow molding machine. There is generally known a so-called molding simultaneous transfer method or the like in which a molding resin is injected or blown after setting a transfer material, transferred at the same time as molding, and taken out from a mold after cooling.

  In the transfer material, it is necessary that the transfer layer be smoothly peeled off from the base film. If the peelability between the transfer layer and the substrate film is poor, the appearance of the surface of the transfer object deteriorates and the transfer layer remains on the substrate film side. Therefore, a film having releasability with respect to the transfer layer is used as the base film.

  In order to impart releasability to a base film, a film provided with a release layer composed of a thermosetting resin layer is known (Patent Document 1). However, in order to give sufficient release properties to the transfer layer, it is necessary to subject the thermosetting layer to a heat treatment at a considerably high temperature or for a long time, resulting in deformation of the base film or an increase in cost. There is a problem.

  In addition, a film in which a wax component is coated on a polyester film has also been proposed (Patent Document 2). However, such a wax component is extremely inferior in heat resistance, and there is a problem that it is softened by heat applied in the transfer layer laminating process and the transfer process, and the releasability becomes unstable or the transfer layer surface is contaminated with wax.

JP-A 61-297172 JP-A-6-286090

  This invention is made | formed in view of the said situation, Comprising: The solution subject is providing the polyester film for transfer materials by which a transfer layer is smoothly transcribe | transferred to a to-be-transferred material.

  As a result of intensive studies on the above problems, the present inventors have found that a film having a specific configuration is useful, and have completed the present invention.

  That is, the gist of the present invention resides in a polyester film for a transfer material, which is a polyester film having a release layer on one side, and the normal release force of the release layer is 2000 mN / cm or less.

Hereinafter, the present invention will be described in detail.
The polyester used for the polyester film for transfer material of the present invention is terephthalic acid, isophthalic acid, 2,6-naphthalenedicarboxylic acid, adipic acid, sebacic acid, 4,4′-diphenyldicarboxylic acid, 1,4-cyclohexyldicarboxylic acid. And melt polycondensation of dicarboxylic acid or its ester with ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, 1,4-butanediol, neopentyl glycol, 1,4-cyclohexanedimethanol Polyester produced. Polyesters composed of these acid components and glycol components can be produced by arbitrarily using a commonly used method. For example, a transesterification reaction between a lower alkyl ester of an aromatic dicarboxylic acid and a glycol, or a direct esterification of an aromatic dicarboxylic acid and a glycol, to form a substantially bisglycol of an aromatic dicarboxylic acid A method is employed in which an ester or a low polymer thereof is formed and then polycondensed by heating under reduced pressure. Depending on the purpose, an aliphatic dicarboxylic acid may be copolymerized.

  Typical examples of the polyester of the present invention include polyethylene terephthalate, polyethylene-2,6-naphthalate, poly-1,4-cyclohexanedimethylene terephthalate, and the like. It may be a polymerized polyester and may contain other components and additives as necessary.

  The polyester film in the present invention preferably has a flat surface after the release layer is provided. When a flatter film is used, the gloss of the product surface after transfer is improved. Therefore, in these polyesters, the surface on which the release layer is provided does not substantially contain particles, or even if particles are contained, the center plane average roughness (SRa) of the release layer surface is 0.020 μm or less, Preferably, it can be contained for the purpose of ensuring the runnability of the film and preventing scratches within the range of 0.015 μm or less.

  In the present invention, in order to make better use of the flat surface, it is preferable that the maximum protrusion height (Rmax) on the surface of the release layer be 0.50 μm or less.

  As particles to be used, inorganic particles such as calcium carbonate, kaolin, silica, aluminum oxide, titanium oxide, alumina and barium sulfate, organic particles such as acrylic resin and guanamine resin, and precipitated particles obtained by atomizing catalyst residue are included. be able to. The particle size and amount of these particles can be appropriately determined according to the purpose.

  In order to flatten the surface of the release layer, there is also a method of providing a release layer thickly so as to cover the protrusions derived from the particles inside the film. It is preferable to provide a release layer. By doing in this way, a mold release layer can be made thin, a process can be simplified or a cost increase can be prevented.

  Further, various stabilizers, lubricants, antistatic agents and the like can be appropriately added to the release layer.

  As a film forming method of the film of the present invention, a generally known film forming method can be adopted, and there is no particular limitation. For example, first, a sheet obtained by melt extrusion is stretched 2 to 6 times at 70 to 145 ° C. by a roll stretching method to obtain a uniaxially stretched polyester film, and then perpendicular to the previous stretching direction in the tenter. A film is obtained by extending | stretching 2 to 6 times at 80-160 degreeC to the direction, and also heat-processing at 150-250 degreeC for 1 to 600 seconds. Further, at this time, a method of relaxing 0.1 to 20% in the longitudinal direction and / or the transverse direction in the maximum temperature zone of the heat treatment and / or the cooling zone at the heat treatment outlet is preferable.

  The polyester film in the present invention has a single layer or multilayer structure. In the case of a multilayer structure, the surface layer and the inner layer, or both surface layers can be made of different polyesters depending on the purpose.

  The polyester film of the present invention preferably has a thickness of 12 to 188 μm.

  In the present invention, the polyester film has a release layer on one side, and the release layer is characterized by a normal peeling force of 2000 mN / cm or less, preferably 1500 mN / cm or less, more preferably 1000 mN / cm or less.

  In the present invention, a fluorine-containing resin is preferably used as one of the components constituting such a release layer. Examples of the fluorine-containing resin include a polymer containing a fluoroolefin or a perfluoroalkyl group. In particular, a polymer obtained by reacting a perfluoroalkyl group-containing ethylenically unsaturated monomer with another ethylenically unsaturated monomer can be suitably used from the standpoint of affinity with a polyester film. Although it does not specifically limit as a perfluoroalkyl group containing ethylenically unsaturated monomer, For example, the compound shown by following General formula (1) is mentioned.

In the general formula (1), R ¹ is H or CH ₃ , R ² is an alkylene group having 1 to 10 carbon atoms, CON (R ³ ) —R ⁴ —, SO ₂ N (R ³ ) — R ⁴ — and Rf is a perfluoroalkyl group having 4 to 20 carbon atoms. R ³ is an alkyl group having 1 to ⁴ carbon atoms, and R ⁴ is an alkylene group having 1 to 10 carbon atoms.

  Further, the release layer may contain a crosslinking reactive compound as necessary. Crosslinking reactive compounds are intended to improve the cohesiveness, surface hardness, scratch resistance, solvent resistance, and water resistance of the coating layer, mainly through crosslinking reactions with functional groups contained in fluorine-containing resins and self-crosslinking. This is preferable. As the crosslinking reactive compound that can be used, amino resins such as melamine, benzoguanamine, and urea, oxazoline, and epoxy are preferably used. Also included are polymer-type cross-linking reactive compounds in which other polymer skeletons have reactive groups.

  If necessary, one or more water-soluble or water-dispersible binder resins can be used in combination. Examples of the binder resin include polyester, polyurethane, acrylic resin, vinyl resin, epoxy resin, amide resin, and the like. In these, each skeleton structure may have a composite structure substantially by copolymerization or the like. Examples of the binder resin having a composite structure include acrylic resin graft polyester, acrylic resin graft polyurethane, vinyl resin graft polyester, and vinyl resin graft polyurethane.

  The release layer in the present invention includes a surfactant, an antifoaming agent, a coating property improving agent, a thickener, an antistatic agent, an organic lubricant, organic particles, inorganic particles, an antioxidant, an ultraviolet absorber, and foaming. Additives such as agents, dyes, and pigments may be contained. These additives may be used alone or in combination of two or more as necessary.

  The ratio of the fluorine-containing resin in the release layer constituting component is usually 15% by weight or more, preferably 20% by weight or more. If the ratio is too lower than these ranges, sufficient release performance may not be obtained. Although the upper limit may be used as a single resin (100% by weight), it is preferably 95% by weight or less, more preferably 90% by weight or less. If the ratio is too high, the film forming property, the coating film strength, etc. may be inferior.

  The release layer according to the present invention is preferably provided by coating, and the coating can be performed by in-line coating performed during film formation, offline coating in which coating is performed after film formation, or other methods. In particular, in the present invention, it is preferably provided by in-line coating.

  In-line coating is a method of coating within the process of manufacturing a polyester film. Specifically, it is a method of coating at any stage from melt extrusion of polyester to biaxial stretching and then heat setting and winding. is there. Normally, it is coated on a substantially amorphous unstretched sheet obtained by melting and quenching, followed by a uniaxially stretched film stretched in the longitudinal direction (longitudinal direction), or a biaxially stretched film before heat setting. To do. Among these, a method in which a uniaxially stretched film is coated, dried in a tenter and stretched in the transverse direction, and further heat-treated with the base film is excellent. According to such a method, since film formation and coating layer coating can be performed simultaneously, there is a merit in manufacturing cost, thin film coating is easy to perform stretching after coating, and heat treatment applied after coating is other than Since the high temperature is not achieved by this method, the film forming property of the coating layer is improved, and the coating layer and the polyester film are firmly adhered. In particular, when used as a release film for a transfer material, it is not preferable that the release layer break or peel in the layer or between the layers. Excellent mode. In particular, when the coating layer contains a cross-linking reactive compound, there is an advantage that the reaction residue hardly remains due to the high-temperature heat treatment of in-line coating. When used as a release film for a transfer material, the presence of a reactive residue in the release layer is undesirable because it may react with the components of the transfer layer in a later step and deteriorate the peelability.

  As a method for applying the coating solution to the polyester film, for example, a coating technique as shown in “Coating system” published by Yuji Harasaki, Tsuji Shoten, published in 1979 can be used. Specifically, air doctor coater, blade coater, rod coater, knife coater, squeeze coater, impregnation coater, reverse roll coater, transfer roll coater, gravure coater, kiss roll coater, cast coater, spray coater, curtain coater, calendar coater And techniques such as an extrusion coater and a bar coater.

  The coating liquid used in the present invention is preferably an aqueous solution or an aqueous dispersion in terms of handling and working environment, but contains water as the main medium and contains an organic solvent as long as it does not exceed the gist of the present invention. You may do it.

The coating amount of the release layer is usually 0.003~1.5g / ^{m 2,} preferably not 0.005 to 0.5 / ^{m 2,} more preferably at 0.01 to 0.3 g / ^{m 2.} If the coating amount of the release layer is less than 0.003 g / m ^2, sufficient performance may not be obtained. A release layer exceeding 1.5 g / m ² may deteriorate the appearance and increase the cost. Invitation is not preferable.

  In the present invention, other coating layers and treatments may be provided on the opposite surface of the release layer.

ADVANTAGE OF THE INVENTION According to this invention, the polyester film which can be used conveniently as a base material of a transfer material can be provided, The industrial utility value is high.

  The present invention will be described in more detail with reference to the following examples. However, the present invention is not limited to the following examples unless it exceeds the gist. In addition, the evaluation method and the processing method of a sample in an Example and a comparative example are as follows.

(1) Normal peel force [mN / cm]
Adhesive tape “No. 502” (manufactured by Nitto Denko Co., Ltd.) is applied to the surface of the release layer, left at room temperature for 1 hour, and then peeled 180 ° at a tensile speed of 300 mm / min with a tensile tester. The value obtained by dividing the average peeling load in the region where the peeling was stable by the width of the adhesive tape was defined as the peeling force.

(2) Measuring method of center plane average roughness (SRa) Non-contact type three-dimensional roughness meter using Al phase deposition on the surface of a 3 cm square film sample and using direct phase detection interferometry, so-called two-beam interferometry ( Under the conditions of a measurement wavelength: 554 nm and objective lens magnification: 20 times under the conditions of Micromap 512), 50 points of the center surface average roughness SRa of the film surface in the measurement region of 232 μm × 177 μm from the projection height distribution curve The average surface roughness (SRa) of the film was determined by averaging the 50 SRa values.

(3) Measuring method of maximum protrusion height (Rmax) Non-contact type three-dimensional roughness meter (micro) using direct phase detection interferometry, so-called two-beam interferometry, by depositing Al on the surface of a 3 cm square film sample. 512) manufactured by Map Inc., and measured the PV value of the film surface in a measurement region of 232 μm × 177 μm over 50 points under the conditions of measurement wavelength: 554 nm and objective lens magnification: 20 times. The values were averaged to obtain the maximum protrusion height (Rmax) of the film.

(4) Transferability evaluation On the surface of the polyester film (the surface where the release layer is provided in the following examples and comparative examples), the release layer composition as shown below is dried and the thickness is 2.5 μm. Then, the adhesive layer composition as shown below is applied and dried so as to have a thickness of 1.5 μm after drying, and a transfer layer having a total thickness of 4 μm is provided. Each layer was dried at 90 ° C. for 30 seconds after coating. The transfer foil test piece thus prepared was used as a molding simultaneous transfer foil for ABS resin, and the surface of the obtained molded body was evaluated by visual observation. The resin was melted and injected at 250 ° C., and the mold was 50 ° C.
(Peeling layer composition): A solution of acrylic resin / vinyl chloride resin in a weight ratio of 80/10. However, toluene / MEK has a weight ratio of 1/1.
(Adhesive layer composition): Vinyl chloride resin solution. However, toluene / MEK has a weight ratio of 1/1.

The polyester raw materials used in Examples and Comparative Examples are as follows.
(Polyester 1): Polyethylene terephthalate chip having an intrinsic viscosity of 0.66 substantially containing no particles

(Polyester 2): Polyethylene terephthalate chip having an intrinsic viscosity of 0.66 containing 0.3 part by weight of amorphous silica having an average particle size of 2.5 μm

Moreover, the following was used as a coating composition of a release layer.
(F-1): CF ₃ (CF ₂ ) _n CH ₂ CH ₂ OCOCH═CH ₂ (n = 5 to 11, n average = 9) 80 which is a perfluoroalkyl group-containing acrylate in a glass reaction vessel 0.0 g, acetoacetoxyethyl methacrylate 20.0 g, dodecyl mercaptan 0.8 g, deoxygenated pure water 354.7 g, acetone 40.0 g, C ₁₆ H ₃₃ N (CH ₃ ) ₃ Cl 1.0 g and C ₈ H ₁₇ C put _{6 H 4 O (CH 2 CH} 2 O) nH (n = 8) 3.0g, added azobisisobutylamidine dihydrochloride 0.5 g, 10 hours copolymerization stirring 60 ° C. under a nitrogen atmosphere Fluorine-containing resin emulsion obtained by reaction.

(B-1): Acrylic acid / styrene copolymer having a glass transition temperature = 16 ° C., and a weight average molecular weight of about 150,000.
(C-1): Crosslinkable resin of alkylol melamine / urea copolymer.
(W-1): An oxidized polyethylene wax having a softening point of 110 ° C.

Example 1:
Polyester 1 and polyester 2 are blended at a weight ratio of 97/3, sufficiently dried, heated and melted to 280 to 300 ° C., extruded into a sheet form from a T-shaped base, and surface temperature using an electrostatic adhesion method. It cooled and solidified, making it closely_contact | adhere to a 40-50 degreeC mirror surface cooling drum, and the unstretched polyethylene terephthalate film was created. This film was stretched 3.7 times in the longitudinal direction while passing through a heating roll group at 85 ° C. to obtain a uniaxially oriented film. An aqueous coating solution in which a resin was dispersed with the composition shown below was applied to this uniaxially oriented film with a Mayer bar. The film was guided to a tenter stretching machine, stretched 4.0 times in the width direction at 100 ° C., and further subjected to heat treatment at 230 ° C., and an amount of 0.03 g / m ² on a base film having a film thickness of 38 μm. A laminated biaxially oriented polyethylene terephthalate film provided with a release layer was obtained. The normal release force of the release layer of this film was 650 mN / cm, SRa on the surface of the release layer was 0.013 μm, and Rmax was 0.42 μm. When this film was used as a base material and the transferability was evaluated, the molded article had good surface gloss and good quality.
Composition of coating solution: 80 parts of resin (F-1) and 20 parts of resin (C-1), where “parts” represents the weight ratio of resin solids.

Example 2:
In the same manner as in Example 1, except that the composition of the coating solution was changed to the following, a laminate 2 in which a release layer having an amount of 0.03 g / m ² was provided on a base film having a film thickness of 38 μm. An axial stretch oriented polyethylene terephthalate film was obtained. The normal release force of the release layer of this film was 1240 mN / cm, the SRa of the release layer surface was 0.013 μm, and Rmax was 0.42 μm. When transferability was evaluated using this film as a base material, the surface gloss of the molded product was slightly inferior to that of Example 1, but was good. The slight deterioration in gloss is presumed to be because the smoothness of peeling of the transfer layer is slightly lower than in Example 1.
-Coating liquid composition: 40 parts of resin (F-1), 40 parts of resin (B-1), 20 parts of resin (C-1), where "parts" means the weight in terms of resin solids Represents the ratio.

Example 3:
In the same manner as in Example 1, except that the weight ratio of polyester 1 and polyester 2 was changed to 73/27, a mold release amount of 0.03 g / m ² was formed on a base film having a film thickness of 38 μm. A laminated biaxially oriented polyethylene terephthalate film provided with a layer was obtained. The normal release force of the release layer of this film was 690 mN / cm, SRa on the surface of the release layer was 0.035 μm, and Rmax was 0.68 μm. When the transferability was evaluated using this film as a base material, the surface of the molded body had a slightly dull appearance due to the transfer of the film surface irregularities, but the transfer was smooth and could be used without any problems.

Comparative Example 1:
In the process of Example 1, a biaxially oriented polyethylene terephthalate film having a film thickness of 38 μm was obtained in the same manner except that the application was not performed. The normal peel force on the film surface was 3580 mN / cm, the SRa on the release layer surface was 0.013 μm, and Rmax was 0.42 μm. When this film was used as a base material for transferability evaluation, the portions where the transfer layer remained without being transferred to the molded body occurred frequently and were defective.

Example 4:
In the same manner as in Comparative Example 1, a biaxially oriented polyethylene terephthalate film having a film thickness of 38 μm was obtained. Next, a coating solution having the same composition as in Example 1 was applied to the film surface with a Mayer bar and dried at 150 ° C. for 1 minute to provide a release layer in an amount of 0.05 g / m ² . The normal peel force on the film surface was 830 mN / cm, the SRa on the release layer surface was 0.013 μm, and Rmax was 0.42 μm. When transferability was evaluated using this film as a base material, transfer was performed smoothly, and the surface gloss of the molded article was good. However, since the release layer was broken and transferred to the transfer layer side, very thin traces of several mm square were scattered in part, giving an impression that the appearance was slightly inferior.

Comparative Example 2:
In the same manner as in Example 1, except that the composition of the coating solution was changed to the following, a laminate 2 in which a release layer having an amount of 0.03 g / m ² was provided on a base film having a film thickness of 38 μm. An axial stretch oriented polyethylene terephthalate film was obtained. The normal release force of the release layer of this film was 2520 mN / cm, the SRa on the surface of the release layer was 0.013 μm, and Rmax was 0.42 μm. When this film was used as a base material for transferability evaluation, the portions where the transfer layer remained without being transferred to the molded body occurred frequently and were defective.
Composition of coating solution: 10 parts of resin (F-1) and 90 parts of resin (C-1), where “parts” represents the weight ratio of resin solids.

Example 5:
In the same manner as in Example 1, except that the composition of the coating solution was changed to the following, a laminate 2 in which a release layer having an amount of 0.03 g / m ² was provided on a base film having a film thickness of 38 μm. An axial stretch oriented polyethylene terephthalate film was obtained. The normal release force of the release layer of this film was 1080 mN / cm, SRa on the surface of the release layer was 0.013 μm, and Rmax was 0.42 μm. When transferability was evaluated using this film as a base material, transfer was performed smoothly, but a slight dullness was observed on the surface of the molded body. This is probably because the release layer was softened by the process of providing the transfer layer or heat at the time of molding, and the release force became unstable or moved to the surface of the transfer layer.
-Coating liquid composition: 100 parts of resin (W-1), where "parts" represents the weight ratio of resin solids.

  The film of the present invention can be suitably used for, for example, a transfer material.

Claims (3)

A polyester film for a transfer material, which is a polyester film having a release layer on one side, and the normal release force of the release layer is 2000 mN / cm or less. The polyester film for transfer materials according to claim 1, wherein the fluorine-containing resin is one of the components constituting the release layer. The polyester film for a transfer material according to claim 1 or 2, wherein the center surface average roughness (SRa) of the release layer surface is 0.020 µm or less.