JP2009167432A - Polyester film for transfer material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polyester film for a transfer material having an antistatic capacity and a blocking preventing capacity to the surface opposite to the transfer layer of the transfer material and capable of not only enhancing the capacity of the transfer material but also reducing trouble accompanying static electricity at the time of production of the transfer material or at the time of a transfer process. <P>SOLUTION: The polyester film for the transfer material has an antistatic layer containing a fluorinated resin on its one side and the surface resistivity of the antistatic layer is 1×10<SP>13</SP>Ω or below and the tack strength with an adhesive tape is set 2.4 N/cm or below. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a polyester film for transfer material.

Generally, a transfer material is configured by sequentially laminating a transfer layer such as a release layer, a design layer, and an adhesive layer on one surface of a base polyester film. Depending on the purpose, a hard coat layer and a metal vapor deposition layer are also laminated as a transfer layer. Furthermore, a functional agent such as an antistatic agent or an antibacterial agent is added to these release layer and transfer layer to give the function.
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 process of manufacturing these transfer materials, if the polyester film of the base material is charged with static electricity, there will be a problem that the pattern will bend during the printing process or the quality may be poor due to the adhesion of dust. Also, in the transfer process, the transfer material is unwound, and if the transfer material is charged with static electricity at this time, the surrounding dust adheres to the transfer material, and a portion where transfer cannot be performed as desired occurs or is molded. In simultaneous transfer, troubles such as giving abnormalities to molded products occur.
On the other hand, recently, an adhesive that adheres strongly at low temperature and low pressure is used as the outermost adhesive layer of the transfer layer of the transfer material for the purpose of improving the transfer speed and improving the adhesion to the transfer object. Many. For this reason, there is a strong tendency for the transfer layer to stick to the opposite surface of the transfer layer of the transfer material, and improvements are required.

JP 2000-355046 A JP 2000-336185 A

  The present invention is intended to solve the above-mentioned conventional problems, and has both antistatic performance and antiblocking performance on the opposite side of the transfer layer of the transfer material, thereby improving the performance of the transfer material and creating the transfer material. It is an object of the present invention to provide a polyester film for transfer material that can alleviate troubles caused by static electricity during the transfer process.

  As a result of intensive studies in view of the above circumstances, the present inventors have found that the above problems can be easily solved by a film having a specific configuration, and have completed the present invention.

That is, the gist of the present invention is a polyester film having an antistatic coating layer containing a fluororesin on one side, and the surface resistivity of the antistatic layer is 1 × 10 ¹³ Ω or less, It exists in the polyester film for transcription | transfer materials characterized by adhesive strength being 2.4 N / cm or less.

  According to the present invention, it is possible to produce a transfer material that can reduce troubles caused by static electricity and blocking problems at the time of creating the transfer material and during the transfer process, and the industrial utility value is great.

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.
These polyesters include 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 catalysts for the purpose of improving film runnability. Precipitated particles in which the residual is made into particles can be contained. The particle size and amount of these particles can be appropriately determined according to the purpose.

In addition, various stabilizers, lubricants, antistatic agents, and the like can be added as appropriate.
As the film forming method of the present invention, a generally known film forming method can be adopted, and there is no particular limitation. For example, first, it is stretched 2 to 6 times at 60 to 120 ° C. by a roll stretching method to obtain a uniaxially stretched polyester film, and then at 80 to 130 ° C. in the direction perpendicular to the previous stretching direction in the tenter. A film can be obtained by stretching the film to -6 times and further performing a heat treatment at 150 to 250 ° C for 1 to 600 seconds.

  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 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.

  The film of the present invention has an antistatic layer having both an antistatic ability and an antiblocking ability. When a low molecular weight anionic antistatic agent widely used as an antistatic agent is used, the polyester film is wound into a roll. In this state, the antistatic agent is transferred to the surface of the transfer layer to be coated with the release layer, adversely affects the release layer coating, or when the transfer layer is rolled up after processing, the antistatic agent is applied to the adhesive layer. Or the adhesive does not perform as desired. In order to prevent such transfer of the antistatic agent, a high molecular weight anionic compound is preferably used. In the case of a cationic antistatic agent, it is desirable to use a high molecular weight cationic compound.

The surface resistivity of the antistatic layer is 1 × 10 ¹³ Ω or less, preferably 1 × 10 ¹² Ω or less. If the surface resistivity exceeds 1 × 10 ¹³ Ω, the antistatic performance is inferior, and problems in the process cannot be improved.

  As described above, the antistatic layer of the present invention is characterized by little or no transfer of the antistatic agent, but at the same time, it should not block the adhesive of the transfer layer. As a guideline that does not cause blocking, the peeling force of the adhesive tape (cello tape (registered trademark)) needs to be 2.4 N / cm or less, preferably 2.0 N / cm or less, more preferably 1. 7 N / cm or less. When this value exceeds 2.4 N / cm, the blocking property improving effect is not obtained.

  Examples of the antistatic agent satisfying such characteristics include a compound having a quaternary ammonium base. This refers to a compound having a component containing a quaternary ammonium base in the main chain or side chain in the molecule. Examples of such constituents include, for example, a pyrrolidinium ring, an alkylamine quaternized product, a copolymer of these with acrylic acid or methacrylic acid, an N-alkylaminoacrylamide quaternized product, a vinylbenzyltrimethylammonium salt, 2-hydroxy 3-methacryloxypropyltrimethylammonium salt etc. can be mentioned. Further, these may be combined or copolymerized with other resins. In addition, examples of anions that serve as counter ions for these quaternary ammonium salts include ions such as halogen, alkyl sulfate, alkyl sulfonate, and nitric acid.

  In the present invention, the compound having a quaternary ammonium base is preferably a polymer compound. When the molecular weight is too low, the antistatic agent is transferred from the antistatic layer to the adhesive layer, and a desired adhesive effect is not obtained, or it adheres to a heating roll or a mold at the time of transfer. In order not to cause such a problem, it is desirable that the number average molecular weight of the compound having a quaternary ammonium base is usually 1000 or more, further 2000 or more, and particularly 5000 or more. On the other hand, when such a compound has a molecular weight that is too high, it may cause problems such as the viscosity of the coating solution becoming too high. In order not to cause such a problem, the number average molecular weight is preferably 500,000 or less.

  In order to reduce the peel strength of the adhesive tape from the adhesive to 2.4 N / cm or less, not only is the selection of the antistatic agent important, but in order to reduce the peel strength, a fluorine resin is actively incorporated. It is effective to do. As the fluororesin, it is preferable to blend a resin having little transfer, preferably no transfer, like the antistatic agent.

  The polymer containing fluorine in the molecule is preferably used as a coating solution as an aqueous dispersion. As a method for preparing an aqueous dispersion, for example, after neutralizing a part of carboxyl groups with a basic compound, There are a method of dispersing in a medium, a method of emulsion polymerization in an aqueous medium using an anionic, cationic, amphoteric and nonionic surfactant as an emulsifier.

  In the present invention, a fluorine-based resin is blended in addition to the antistatic agent as the antistatic layer. Further, in the antistatic layer, one of water-soluble or water-dispersible binder resins other than those described above or Two or more types may be used in combination to improve coatability. Examples of the binder resin include polyester, polyurethane, acrylic resin, vinyl resin, epoxy resin, amide resin, and polyvinyl alcohol. 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.

  Further, in the present invention, the antistatic layer may contain a crosslinking reactive compound. The cross-linking reactive compound cross-links with the functional group of the component compound constituting the antistatic layer, thereby preventing transferability and preventing transfer to a heating roll or mold during transfer. Further, the addition of the crosslinking agent improves the adhesion (blocking property), water resistance, solvent resistance, mechanical strength and the like of the coating layer. Examples of the crosslinking agent used in the present invention include a melamine crosslinking agent and an epoxy crosslinking agent. Examples of the melamine-based crosslinking agent include methoxymethylated melamine and butoxymethylated melamine which are alkylol or alkoxyalkylolated melamine compounds, and those obtained by co-condensing urea or the like with a part of melamine can also be used. The epoxy-based crosslinking agent may be a compound having an epoxy group that is water-soluble or has a water-solubilization rate of 50% or more.

  The antistatic layer of the present invention may contain at least one additive such as an antifoaming agent, a coating property improver, a thickener, an organic lubricant, organic particles, and inorganic particles, if necessary. Good.

The film of the present invention preferably has a surface oligomer amount of 0.01 to 2.1 mg / m ² after heat-treating the surface with the antistatic layer at 180 ° C. for 10 minutes. The surface oligomer is determined by the following method. That is, the polyester film was heat-treated in an oven in a nitrogen gas atmosphere at 180 ° C. for 10 minutes, and then only the notable surface was immersed in dimethylformamide (DMF) for 3 minutes, and the amount of oligomer dissolved in DMF was quantified by liquid chromatography. It is a method of doing.

  As for the transfer method using a transfer material, the hot stamping method and the simultaneous molding transfer method have been explained earlier. In both methods, the heating roll and mold are stained by the polyester oligomer on the polyester film surface, and the number of transfers is reduced. As it accumulates, it accumulates on the heating roll and mold. These oligomers eventually leave a mark on the transfer surface transferred to the transfer target, deteriorate the gloss of the transfer surface, and, in extreme cases, distort the transfer target. In the case of the simultaneous molding transfer method, this tendency is strong because the flowing resin and the transfer material are in contact with each other. For this reason, the transfer surface, the heating roll, and the mold of the transfer target are monitored, and the heating roll and the mold are appropriately cleaned, but this is a factor that reduces the processing efficiency.

  In view of such a current situation, the present inventors set the amount of the film surface oligomer after heat-treating the surface having the antistatic layer of the present invention at 180 ° C. for 10 minutes within the above range, whereby a heating roll or a mold is used. It was found that the dirt was remarkably reduced, and the frequency of cleaning could be remarkably reduced.

  As a method for suppressing the amount of the surface oligomer, the present inventors have found that, for example, the above-described compound having a quaternary ammonium base may be used as an antistatic agent, but the surface oligomer of the present invention is suppressed. The compound for this purpose is not limited to this antistatic agent, and a silane coupling agent, an acrylic resin, polyvinyl alcohol, or the like may be blended.

  As a method for inhibiting the surface oligomer, a polyester raw material having a low oligomer content can be used. Such a raw material is obtained by solid-state polymerization in which a polyester chip obtained by a usual melt polycondensation reaction is kept at 180 ° C. to 240 ° C. for about 1 hour to 20 hours under reduced pressure or under the flow of an inert gas. Can do. A single-layer polyester film may be formed by mixing only this raw material or this raw material and a normal raw material, or a multilayer structure of two or more layers, and this raw material is used only for the surface layer opposite to the transfer layer. May be. In the case of a multilayer structure, normal polyethylene terephthalate may be used for the inner layer, and for simultaneous molding transfer, for the purpose of improving moldability, copolymerized polyester or polybutylene containing isophthalic acid and terephthalic acid as a copolymerization component. Terephthalate may be used.

  The antistatic layer has a dry thickness of usually 0.003 to 1.5 μm, preferably 0.005 to 0.5 μm. When the thickness of the antistatic layer is less than 0.003 μm, sufficient performance may not be obtained, and when it exceeds 1.5 μm, blocking between the films tends to occur.

  As a method of providing an antistatic layer on a polyester film, a biaxially stretched film may be coated by a conventional technique, or may be coated by a conventional technique in the process of producing a polyester film. For example, in the sequential biaxial stretching method, there is a method in which a film after longitudinal uniaxial stretching is coated with an antistatic agent and then stretched laterally, followed by thermal heat treatment, or a method of coating and drying after biaxially stretched film. . Although the method is not limited, the method of coating a uniaxially stretched film, then laterally stretching, and heat-treating is preferable because it has a feature that the coat layer can be uniformly thinned.

  As a method of coating the polyester film with an antistatic agent, 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 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. Further, “parts” in Examples and Comparative Examples represents “parts by weight”.

(1) Measuring method of surface resistivity Using a high resistance measuring instrument (HP4339B) and measuring electrode (HP16008B) manufactured by Hewlett-Packard Japan, apply the sample after sufficient humidity control in a measurement atmosphere of 23 ° C and 50% RH The surface resistivity of the coating layer after 1 minute at a voltage of 100 V was measured.

(2) Method of measuring peel strength with adhesive tape Adhesive tape (Nichiban cello tape (registered trademark)) was applied to the surface of the solvent-resistant layer of the substrate film, and measured at 23 ° C. and 50% RH in a measurement atmosphere. After partial humidity control, the peeling load when peeling the adhesive tape at an angle of 180 degrees at a speed of 300 mm / min was measured with an Intesco tensile tester.

(3) Measuring method of intrinsic viscosity [η] (dl / g) of polymer 1 g of polymer is dissolved in 100 ml of a mixed solvent of phenol / tetrachloroethane = 50/50 (weight ratio), and 30 ° C. using an Ubbelohde viscometer. Measured with

(4) Method for measuring oligomer in polyester raw material After dissolving a predetermined amount of polyester raw material in o-chlorophenol, reprecipitation with tetrahydrofuran and filtering to remove linear polyethylene terephthalate, the filtrate obtained was It supplied to the liquid chromatograph (Shimadzu LC-7A), the oligomer amount contained in polyester was calculated | required, and this value was divided by the polyester amount used for the measurement, and it was set as the oligomer amount contained in polyester. The amount of oligomer determined by liquid chromatography was determined from the peak area ratio between the standard sample peak area and the measured sample peak area (absolute calibration curve method). The standard sample was prepared by accurately weighing a preliminarily prepared cyclic trimer of polyethylene terephthalate and dissolving it in DMF (dimethylformamide) accurately measured. The conditions for the liquid chromatograph were as follows.
Mobile phase A: Acetonitrile mobile phase B: 2% acetic acid aqueous solution column: MCI GEL ODS 1HU manufactured by Mitsubishi Chemical Corporation
Column temperature: 40 ° C
Flow rate: 1 ml / min Detection wavelength: 254 nm

(5) Polyester film heat treatment and oligomer measurement method Overlay the polyester film on the A4 size Kent paper so that the oligomer measurement surface is on the outside, clip the four corners, and stop the Kent paper and the polyester film. In this state, the sample was put in an oven at 180 ° C. under a nitrogen atmosphere, left to stand for 10 minutes, and then taken out. Next, create a box by folding the four sides so that the bottom of the polyester film oligomer measurement surface faces inward (12.5 cm x 20 cm), and put about 10 ml of dimethylformamide (DMF) in this box. After soaking for 3 minutes, the amount of oligomer dissolved in DMF was determined and determined. In quantification, the amount of oligomer in the solution finally made to 10 ml was determined from the peak area ratio of the standard sample peak area and the measured sample peak area using a liquid chromatograph (Shimadzu LC-7A) (absolute calibration curve method). ). The standard sample was prepared by accurately weighing a preliminarily prepared cyclic trimer of polyethylene terephthalate and dissolving it in DMF (dimethylformamide) accurately measured. The unit is shown in mg / m ² . The liquid chromatograph measurement conditions were as follows.
Mobile phase A: Acetonitrile mobile phase B: 2% acetic acid aqueous solution column: MCI GEL ODS 1HU manufactured by Mitsubishi Chemical Corporation
Column temperature: 40 ° C
Flow rate: 1 ml / min Detection wavelength: 254 nm
The polyester raw materials used in the examples and comparative examples were produced by the following method.

  Polyester chip having an intrinsic viscosity of 0.58 (hereinafter referred to as chip A) and polyester chip having an intrinsic viscosity of 0.66 containing 0.06 part of amorphous silica having an average particle size of 2.5 μm by an ordinary melt polymerization method (Hereinafter referred to as Chip B) was manufactured. Chip A was heated in a nitrogen stream at 220 ° C. for 10 hours to produce a polyester chip having a low oligomer content (hereinafter referred to as chip C). The amount of oligomer contained in chip B was 0.83% by weight, and the amount of oligomer contained in chip C was 0.24% by weight. These chips were used after being sufficiently dried and having a water content of 50 ppm or less.

  The aqueous coating solution raw materials used in the examples and comparative examples are as follows.

Antistatic agent (A1): polydiallyldimethylammonium chloride (average molecular weight: about 30000)
Aqueous resin (B1): partially saponified polyvinyl alcohol (degree of saponification: about 88 mol%)
Aqueous resin (B2): Fluorine-based resin water dispersion release agent (Mcclave made by GSI Creos)
Crosslinking agent (C): Methoxymethylol melamine (Dainippon Ink Co., Ltd., Becamine J101)

The raw material composition of the aqueous coating liquid used in Examples and Comparative Examples was as follows.
Coating solution (1): An aqueous solution having a concentration of 3.0% was prepared so that the antistatic agent (A1) was 40 parts, the aqueous resin (B2) was 30 parts, and the crosslinking agent (C) was 30 parts.
Coating solution (2): An aqueous solution having a concentration of 3.0% was prepared so that the antistatic agent (A1) was 40 parts, the aqueous resin (B1) was 40 parts, and the crosslinking agent (C) was 20 parts.

Comparative Example 1
Chip B was melted at 295 ° C., melted and extruded onto a cooled drum to obtain an amorphous sheet, and then stretched 3.5 times vertically at 85 ° C. to 100 ° C. to obtain a longitudinally uniaxially stretched film. This film was stretched 4.0 times horizontally in an atmosphere of 85 ° C. to 110 ° C. and then heat treated at 235 ° C. to obtain a biaxially stretched polyester film having a thickness of 38 μm. The surface resistivity of the obtained film was 5 × 10 ¹⁴ Ω, and the film was easily charged. Moreover, the surface oligomer amount was 3.0 mg / m < ² >. When this was used as a transfer foil, the yield was not good due to the entrainment of dust accompanying charging, and the mold was noticeably soiled by the oligomer.

Example 1
The longitudinally uniaxially stretched film of Comparative Example 1 is coated with the above coating solution (1) with a gravure coater to a thickness of 5 μm, stretched 4.0 times horizontally in an atmosphere of 90 ° C. to 120 ° C., and then to 235 ° C. To obtain a biaxially stretched polyester film having a thickness of 38 μm. The surface resistivity of the coated surface of this film was 2 × 10 ⁹ Ω, and it was a film that could prevent charging. Moreover, the peeling force with the adhesive tape was 2.3 N / cm, and the surface oligomer amount was 0.6 mg / m ² . When this film was used as a transfer foil, there was no blocking, no trouble with charging, and the processing yield was improved.

Comparative Example 2
A polyester film was obtained in the same manner as in Example 1 except that the coating solution was the above-described coating solution (2). The surface resistivity of this film was 1 × 10 ⁹ Ω, and it was a film that could prevent charging. Moreover, the peeling force with an adhesive tape was 2.8 N / cm. When this film was used as a transfer foil, there was no trouble associated with charging, but the processing yield decreased due to a trouble caused by blocking.

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

Claims (1)

It is a polyester film having an antistatic coating layer containing a fluorine resin on one side, the surface resistivity of the antistatic layer is 1 × 10 ¹³ Ω or less, and the adhesive strength with the adhesive tape is 2.4 N / cm A polyester film for transfer material, characterized by: