JPH0292589A - Polyester film for thermal transfer material - Google Patents

Abstract

PURPOSE:To eliminate the occurrence of sticking even under a high printing energy to prevent such troubles as the contamination of a thermal head and a running failure by specifying an Si/C atom number ratio attributed to a bifunctional siloxane in a protective layer each in the outer and inner layers of the protective layer. CONSTITUTION:The title film is a laminated film having a protective film on one surface of a biaxially oriented polyester film. An Si/C atom number ratio attributed to a bifunctional siloxane in the protective layer is determined to be 0.15-0.40 in the outer layer of the protective layer and 0.05 or less in the inner layer thereof. When the Si/C atom number ratio in the outer layer of the protective layer is less than 0.15, sticking and running properties cannot be sufficiently improved. When it is more than 0.40, the effect on improving sticking and running properties can be obtained, but the insufficient strength of the outer layer of the protective layer induces the contamination of a thermal head. On the other hand, when the Si/C atom number ratio in the inner layer of the protective layer is more than 0.05, the adhesion of the polyester film substrate with the protective layer is insufficient, and the resulting removal of the protective layer causes the contamination of the thermal head.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a polyester film suitable as a base material for a thermal transfer material used in a thermal printer or the like, ie, a thermal transfer ribbon or a thermal transfer sheet.

[Prior Art] A heat-sensitive transfer material in which a coloring material layer is coated on one side of a biaxially oriented polyester film and a heat-resistant protective layer such as silicone resin or melamine resin is coated on the other side is disclosed in Japanese Patent Application Laid-open No. 55-7467.58-13359.60-2499
It is well known from publications such as Publication No. 5. In addition, polyester film as a base material for such thermal transfer materials was also developed in Japanese Patent Application Laid-open No. 6
0-217194.60-192628.62-193
It is publicly known from 889.62-233227 and the like.

[Problems to be Solved by the Invention] However, as recent thermal transfer technology moves toward high-speed printing, that is, high-thermal energy printing, various problems have arisen. For example, the thermal head and the back of the thermal transfer material stick together, pull (this problem is called sticking), thermal head contamination due to poor adhesion between the protective layer and the substrate, and the guide plate of a thermal printer where heat is accumulated. and problems with running performance due to poor lubricity between the guide roll and the thermal transfer material, etc. When the thermal transfer materials and films according to the above-mentioned conventional techniques are used as thermal transfer materials, any of the above-mentioned disadvantages may occur. It had

The object of the present invention is to provide a polyester for thermal transfer materials that does not have the above-mentioned drawbacks when used as a thermal transfer material, that is, does not cause sticking even under high printing energy, and does not cause problems such as contamination of the thermal head or poor running performance. The goal is to provide film.

[Means for Solving the Problems] The present invention provides a laminated film in which a protective layer is provided on one side of a biaxially oriented polyester film, in which the Si/C atomic ratio attributed to the bifunctional siloxane in the protective layer is The main feature of the film is a polyester film for heat-sensitive transfer materials, which is characterized in that the outer layer has an angle of 0.15 to 0.40 degrees, and the inner protective layer has an angle of 0.05 or less.

Here, the inner layer of the protective layer refers to the surface layer on the biaxially oriented polyester side within the protective layer, and the outer layer of the protective layer refers to the surface layer on the opposite side.

Polyester here is a general term for polymers that have ester bonds as the main bond chain in the main chain, and particularly preferred polyesters include polyethylene terephthalate,
polyethylene 2,6-naphthalate, polyethylene α,
β-bis(2-chlorophenoxy)ethane 4,4'-dicarboxylate, polybutylene terephthalate, etc. Among these, polyethylene terephthalate 1~ is the most preferable, considering quality, economical efficiency, etc. . Therefore, hereinafter, we will proceed with the description using polyethylene terephthalate as a representative polyester.

Polyethylene terephthalate (hereinafter referred to as PET) in the present invention
80 mol% or more, preferably 90 mol% or more, more preferably 95 mol% or more of ethylene terephthalate as a repeating unit, but within this limited amount range, the acid component and/or Alternatively, part of the glycol component may be replaced with a third component as described below.

-Acid component- Isophthalic acid, 2,6-naphthalene dicarboxylic acid, 1,
5-naphthalenedicarboxylic acid, 2,7-naphthalenedicarboxylic acid, 14.4'-diphenyldicarboxylic acid, 4.4
'-Diphenylsulfonedicarboxylic acid, 4,4'-diphenyletherdicarboxylic acid, azelaic acid, cepatic acid, hexahydroterephthalic acid, hexahydroisophthalic acid, ε-oxycaproic acid, trimellitic acid, trimesic acid, pyromellitic acid, α,β-bisphenoxyethane-4,4'-dicarboxylic acid, α,β-bis(2-chlorophenoxy)ethane-4,4'-dicarboxylic acid, 5-sodium sulfoisophthalic acid monoglycol component-propylene glycol, butylene Glycol, hexamethylene glycol, decamethylene glycol, neobenzene gelicol,],]1-cyclohexane dimetatool 1.4-cyclohexane dimetatool, 2.2-bis(4-β-hydroxyethoxyphenyl)propane,
Bis(4-β-hydroxyethoxyphenyl)sulfone, diethylene glycol, triethylene glycol, pentaerythritol, trimethylolpropane, polyethylene glycol, etc.

PET also contains known additives, such as heat stabilizers, oxidation stabilizers, weather stabilizers, ultraviolet absorbers, organic lubricants, pigments, dyes, organic or inorganic fine particles, fillers, and release agents. A molding agent, an antistatic agent, a nucleating agent, etc. may be added.

The intrinsic viscosity of PET as described above (measured in orthochlorophenol at 25°C) is 0.40 to 1.20,
Preferably 0.50 to 0.80, more preferably 0.
Those in the range of 55 to 0.75 dl/9 are suitable for the content of the present invention.

Next, the biaxially oriented polyester film as used in the present invention refers to a polyester sheet or film in an unstretched state.
2 in each of the so-called biaxial directions, the longitudinal direction and the width direction.
It is made by stretching about 5 to 5 times, and shows a biaxial orientation pattern in wide-angle X-ray diffraction.

The thickness of the biaxially oriented polyester film is not particularly limited, but is usually 0.5 μm or more and 40 μm or less, preferably 1
When it is 10 μm or more, it is suitable as a base film of a heat-sensitive transfer material.

Furthermore, the surface average roughness of the biaxially oriented polyester film is not particularly limited, and is usually 0.04 to 0.4 μm, preferably 0.07 μm to 0.2 μm.

In the present invention, in the protective layer provided on one side of the biaxially oriented polyester film, Si/
C atomic ratio is 0.15 to 0.40 in the outer protective layer,
Preferably 0.18 to 0°35, more preferably 0.2
0 to 0.30, and in the inner layer of the protective layer, it needs to be 0.05 or less, preferably 0.03 or less, and more preferably 0.01 or less. Here, bifunctional siloxane is one formula%
It is represented by the formula %, and R is selected from an alkyl group having 1 to 100 carbon atoms, a hydroxyl group, hydrogen, an epoxy group, an amino group, a carboxyl group, a phenyl group, a mercapto group, and an alkyl group containing a halogen; It is preferable that R is a methyl group because the effects of the present invention are more pronounced. If the 3i/C atomic ratio in the outer layer of the protective layer is less than 0.15, the improvement in sticking and runnability is insufficient, and the
If it exceeds 40°, although the effect of improving sticking and runnability is recognized, the strength of the outer protective layer becomes unstable, and 1
Normal head contamination occurs. Furthermore, if the Si/C atomic ratio inside the protective layer exceeds 0.05, the adhesion between the base polyester film and the protective layer will be insufficient, and the thermal head will be contaminated due to the protective layer falling off.

Good characteristics are exhibited only when the Si/C atomic ratio is within the range of the present invention.

The thickness of the protective layer is not particularly limited, but is usually 0.03 μm to 1 μm.
It is desirable that the thickness is .mu.m, preferably 0.05 .mu.m to 0.3 .mu.m.

Examples of the difunctional siloxane-containing substance include various organosiloxane monomers, oligomers, and polymers, but it is preferable to use polymers in view of the toughness of the coating film. Preferred representative examples for achieving the effects of the present invention include organopolysiloxanes containing dimethylpolysiloxane as one component, and organopolysiloxanes containing dimethylpolysiloxane and various other functional groups. A copolymer of is more preferred.

Here, H3 occupies in the organopolysiloxane, where n is an integer of 1 to 5,000. ), and a reactive group other than the organosiloxane H3 group other than dimethylsiloxane, a non-reactive group, and m represents an integer of 1 to 5000. ), the dimethylsiloxane content expressed as n/(n0m> is 0.30 or more and 0.95 or less 1
, preferably from 0.50 to 0.180, is particularly suitable for obtaining the protective layer of the present invention. Such organopolysiloxanes include dimethylpolysiloxane, amino-modified silicone, amino-glycol-modified silicone, epoxy-modified silicone, epoxy-polyether-modified silicone, carboxyl-modified silicone, alcohol-modified silicone, alkyl- and aralkyl-modified silicone, alkyl◆aralkyl Examples include φ polyether-modified silicone, alkyl/higher alcohol-modified silicone-modified silicone, fluorine-modified silicone, methylhydrodiene polysiloxane, methylphenyl polysiloxane, mercapto-modified silicone, chloroalkyl-modified silicone, vinyl group-containing silicone, etc. . Also, two or more of these may be used in combination.

These organopolysiloxanes can be used by dissolving or dispersing them in any solvent, but it is more preferable to use those dissolved or suspended in water in order to avoid environmental pollution and ignition and explosion during the production process.

Organopolysiloxane may be used alone as a protective layer, but since the film-forming properties and adhesion of the coating film are insufficient, it is usually preferable to use it in combination with a thermoplastic or thermosetting resin. The thermoplastic resin and thermosetting resin are not particularly limited, but those that have good adhesion to the base polyester film are preferred, and those that exhibit a crosslinked structure when reacted with organopolysiloxane having a functional group are more preferred.

Specific examples include polyester resins, urethane resins, acrylic resins, epoxy resins, amide resins, etc., and those having reactivity themselves are particularly preferred. Two or more of these may be used as a mixture, and a crosslinking catalyst may be used in combination if necessary. These thermoplastic and thermosetting resins can be dissolved or dispersed in any solvent, but it is preferable to use them dissolved, emulsified, or suspended in water to avoid environmental pollution and ignition and explosion during the manufacturing process. More preferred.

The content of organopolysiloxane in the protective layer is not particularly limited as long as it satisfies the constituent requirements of the present invention, but from the viewpoint of the toughness of the coating film, it is 10 to 50% by weight, preferably 15 to 40% by weight. is desirable.

In order to bring out the effects of the present invention, the coating solution mixed with the organopolysiloxane and resin is applied to a polynisdel film before crystal orientation is completed, and the film is stretched and heat-treated under specific conditions to achieve a film thickness of 1q. It is something. In other words, in the process of applying and stretching a coating solution containing a mixture of organopolysiloxane, thermoplastic, and thermosetting resin, it is preferable to stretch the coating film in a state where no solvent is present in the film. It is effective to use methods such as keeping the preheating temperature sufficiently long, increasing the stretching temperature and increasing the stretching speed within a range that does not cause defects such as film tearing or negging stretching. The liquid S degree is 2 to 20 wt%, preferably 3 to 10 wt%, and the stretching temperature is 98 to 180°C, preferably 110 to
The stretching speed is preferably 150°C, and should be appropriately selected depending on the stretching temperature, for example, about 10,000%/min to 40oooo%/min.

Furthermore, it is important that moisture be present in the atmosphere during the stretching process. Specifically, this is achieved by stretching in pressurized water or in the presence of pressurized steam during the stretching process. The temperature at this time needs to be 10% RH or more, preferably 25% RH or more as a value at the surface layer of the film to be stretched. It is also important to perform heat treatment at 180 to 250°C after stretching. That is, there is no moisture in the coated film, but moisture is present only in the surface layer of the 1i film during stretching, and the structure of the protective layer of the present invention is achieved by subsequently heat-treating at a high temperature.

Next, a typical method of manufacturing a polyester film for thermal transfer materials of the present invention will be described using polyethylene terephthalate (hereinafter abbreviated as PET) as a typical example of polyester, but it is of course not limited to this. do not have.

So-called precipitated particles and inorganic fine particles (
For example, PE containing colloidal silica with a particle size of 1 μm)
T was dried and melt-extruded according to a conventional method, and the extruded sheet 1
The ~-shaped melt is cooled and solidified to produce an unstretched PET film. This film is heated to 80 to 120°C and stretched 2.5 to 5 times in the longitudinal direction to form a uniaxially oriented film. One side of this film is subjected to a corona discharge treatment in a carbon dioxide gas atmosphere, and a mixed coating liquid of a thermoplastic or thermosetting resin and an organopolysiloxane is applied to this treated side. After that, it is sufficiently dried in a preheating step and then stretched 3 to 6 times in the width direction while being humidified with pressurized steam at 98 to 180'C. 18 consecutively
The sample is introduced into a heat treatment zone at 0 to 250°C and subjected to heat treatment for 1 to 10 seconds. During this heat treatment, it is better to loosen ash by 3-12% in the width direction. Also, 1.1-1.7 as necessary.
It may be stretched again in the machine direction.

Coating 15 The coating method is not particularly limited, and may include extrusion lamination,
Melt coating methods may be used, but since it is possible to coat a thin film at high speed, gravure coating, reverse coating, spray coating, kiss coating, die coating, and barcoding are used with coating liquids dispersed in water spray or various solvents. is preferable.

The thus obtained polyester film for thermal transfer material is coated with a coloring material layer and then shredded into appropriate widths for use in word processors, facsimile machines, computer printers, etc.
It is used for printing out characters or images with video printers, barcode printers, typewriters, plain paper copiers, etc.

Method for Measuring Characteristics and Evaluating Effects] Methods for measuring characteristics and evaluating effects in the present invention are as follows.

(1) Si/C atomic ratio assigned to bifunctional siloxane in outer layer and inner layer of protective layer Measured by ESCA method under the following conditions.

Equipment: viJll Manufacturing ESCA750 Excitation X-ray: I
VtgKα1,2 line (hν=1253°6eV) Energy correction: The binding energy (BEE) value of the C1s main peak was adjusted to 2846eV.

Photoelectron escape m: 30° with respect to the sample surface (detection depth 2 surfaces ~ 50 people) The atomic ratio Si/C was determined from the peak area of the photoelectron peak thus determined.

Further, Si assigned to the bifunctional siloxane was identified from the 3i2p peak position.

The Si/C atomic ratio of the outer layer of the protective layer was measured from the surface of the protective layer using the method described above. For the inner layer of the protective layer, a cross section of the protective layer was cut out by a freezing method, and the position of the cross section closest to the base film side was measured. If measurement at this cross section is not possible, measure the 288 intensity in the depth direction of the protective layer using a secondary ion quality analyzer (SIMS) and calculate the 2881-intensity at the deepest part of the protective layer, which corresponds to 1710 of the coating thickness. The value was taken as the value for the inner layer of the protective layer.

The thickness of the protective layer was measured by enlarging a cross section cut out by the freezing method 100,000 times. Measurements were made at 10 locations each in the longitudinal direction and the width direction, and the average value was taken as the average value. The 283 i-intensity determined by the SIMS method is extrapolated from the known values measured by the ESCA method and the SIMS method, and the 28Si- intensity determined by the SIMS method is
The strength was converted into Si/C using the ESCA method. The measurement conditions of the SIMS method are as follows.

Equipment: Secondary ion trade analyzer (SIMS>West German ATO)
MIKA A-DI DA primary ion species: Cs
+ Primary ion acceleration voltage: 12kV Primary ion current: 30nA Raster area: 400μm Open analysis area: Gate 30% Measurement vacuum: 1X10-8 Torr +-1-Q-H: #12 (2) Hot stick on one side A sublimable ink having the following composition was applied to the other side of the biaxially oriented polyester film provided with the protective layer, dried, and then slit to an appropriate width to prepare a heat-sensitive transfer material.

[Sublimable ink layer composition] Disperse dye KST-B-1364 interlayer part (manufactured by Nipponka vA) Ediyl hydroxyethyl cellulose 6 parts by weight Methyl ethyl ketone 45 parts by weight Toluene
This heat-sensitive transfer material was run on the following printer (45 times) and the voltage at the time of hot stick generation was measured by changing the applied voltage.The printer was run under normal operating conditions except that the applied voltage was changed.

Interface type printer Nijisave color video printer G
Z-Pi 1W (3) Contamination of the thermal head A heat-melting ink layer having the following composition is applied to the other side of the biaxially oriented polyester film with a protective layer provided on one side by the hot-melt method, and slit to an appropriate width to print the sensitizer. I made a heat transfer material.

[Hot melt ink layer composition] Carnauba wax 100 parts by weight Microcrystalline wax 30 parts by weight Vinyl acetate/ethylene copolymer 15 parts by weight Carbon black
20 parts by weight This thermal transfer material was put into the following thermal printer, and the thermal head was run under normal conditions of use at 100 times magnification using an optical microscope, and the contamination state was determined according to the following criteria.

Sumaru Printer: Mitsubishi Inner Thermal Color Printer Model G500F-10 ◎: No contaminants attached ○: Almost no contamination (contaminated area less than 10%) Δ: Considerable contamination ( (Contaminated area: 10% or more and less than 30%) ×: Significant contamination.

(Contaminated area of 30% or more) (3) Running performance Running performance with guide rolls and guide plates was determined by measuring the static friction coefficient (μS) and dynamic friction coefficient (μd) between the protective layer surface and a mirror-finished hard chrome plate at 80°C. Both μS and μd are 0.
A value of 25 or less was determined to be "good", and a value exceeding 25 was determined to be "bad". The measurement was performed using a slip tester according to ASTM-D-18948-63.

[Effects of the Invention] The present invention provides a protective layer on one side of a biaxially oriented polyester film, and sets the Si/C atomic ratio attributed to bifunctional siloxane to a specific range in the outer layer and inner layer of the protective layer. This is a 1q polyester film for thermal transfer materials that prevents stickiness, prevents contamination of the thermal head due to falling off of the protective layer, and improves runnability due to improved lubricity with guide plates, guide rolls, etc.

[Example] Next, the present invention will be explained based on examples.

Example 1 0.15% by weight of precipitated particles with a particle size of 0.5 to 1.5 μm (particles precipitated during the Φ combining process) and a particle size of about 1.5 μm
PET pellets (intrinsic viscosity: 0.63 dl/g) containing 0.2% by weight of calcium carbonate particles were sufficiently vacuum-dried, then fed to an extruder and melt-extruded at 280°C.
After filtering through a metal sintered filter with a 0 μm cut, it was extruded into a sheet through a T-shaped nozzle, and the sheet was wound around a cooling drum with a surface temperature of 50° C. to cool and solidify. In order to improve the adhesion between the sheet and the surface of the cooling drum during this time, a wire electrode was placed on the sheet side and a DC voltage of 6000 V was applied. The unstretched PET film thus obtained was
It was heated to 5° C. and stretched 3.5 times in the longitudinal direction to obtain a -axis stretched film. One side of this film was subjected to corona discharge treatment in a carbon dioxide gas atmosphere, and a water-based paint with the following composition was applied to the treated side using a gravure coating method to a coating thickness of 0 after biaxial stretching.
．． It was coated to a thickness of 1 μm.

[Coating composition] Thermoplastic acrylic resin emulsion 67 parts by weight (methyl methacrylate/ethyl acrylate -1~(50150
) Mol%, molecule m300,000 > Epoxy polyether modified silicone (dimethylsiloxane content 0.82, viscosity 2000 centivoice) 30 parts by weight Phosphorus M2 Ammonium hydrogen 3 parts Diluted with water to obtain a solid concentration of 5 parts by weight Furthermore, 1.2 parts by weight of a fluorine-based surfactant was added as a coating property improver based on the total solid content, and the mixture was uniformly stirred and mixed to prepare a water-based paint having a viscosity of 4 cm at 20'C.

After coating, the moisture was thoroughly dried in a preheating process at 110°C, and then the atmosphere was heated and humidified to 140°C with raw steam, stretched 4.5 times in the width direction in a tenter, and then stretched at 210°C. Heat treated for 5 seconds with a protective layer thickness of 0.1
A polyester film for thermal transfer material having a base film thickness of 6 μm was obtained. The Si/C atomic ratio attributed to the bifunctional siloxane in the protective layer of this film was 0.23 in the outer protective layer and 0.01 in the inner protective layer. An ink layer was coated on the protective layer and anti-lunar surface of this film to prepare a heat-sensitive transfer material. This thermal transfer material has a voltage of 16.5V, which exceeds the normal voltage of 14.5V for dye-sublimation printers.
No sticking occurred until then. Further, the contamination state of the thermal head was [O], and the running performance was also at [Good] level.

Comparative Example 1 A polyester film for a thermal transfer material was produced in the same manner as in Example 1 except that the width direction stretching conditions and heat treatment conditions used in Example 1 were changed. In other words, the applied paint stretches in the width direction before it has fully dried during the preheating process.
The heat treatment temperature was 160°C. The Si/C atomic ratio of the protective layer of this film was 0.12 in the outer layer and 0.10 in the inner layer. A thermal transfer material was prepared using this film in the same manner as in Example 1. Sticking occurred in this thermal transfer material at a voltage of 12 V, which is below the voltage normally used in a sublimation printer. In addition, due to the poor adhesion of the adhesive, the thermal head was significantly contaminated at a level of [x1], and the running performance was also "poor".

Comparative Example 2 5% by weight of the paint used in Example 1 was applied to a commercially available biaxially oriented polynisdel film, dried, and the thickness of the protective layer was 0.1 μm.
19 m laminated film. S of the protective layer of this film
The i/C atomic ratio was 0.11 in the outer layer and 0.13 in the inner layer.

A thermal transfer material was prepared using this film in the same manner as in Example 1, but the sticking generation voltage was 11.5 V, the thermal head contamination was [X], and the runability was at the level of [Poor].

Comparative Example 3 A polyester film for a thermal transfer material was produced in the same manner as in Example 1 except that the coating composition was changed as shown below.

[Coating composition] Dimethylpolysiloxane emulsion 100 parts by weight This coating material was diluted with water in the same manner as in Example 1, and a coating film I was formed so that the coating thickness after biaxial stretching was 0.1 μm. The Si/C atomic ratio of the protective layer of the film thus obtained was 0.
50, and also 0.50 in the inner layer. When this film was evaluated as a heat-sensitive transfer material, the potstick resistance and running properties were good, but the thermal head staining was at the [X] level.

Claims (1)

[Claims] In a laminated film in which a protective layer is provided on one side of a biaxially oriented polyester film, the Si/C atomic ratio attributable to the bifunctional siloxane in the protective layer is 0.15 to 0.40 in the outer layer of the protective layer; 0 in the inner layer.
1. A polyester film for thermal transfer material, characterized in that the polyester film is 05 or less.