JPS6072790A - Manufacture of thermal transfer recording medium - Google Patents

Abstract

PURPOSE:To raise the adhesiveness of a coloring layer to a film supporter as well as to reduce the cost of manufacture by covering a stretched polymer film with a coloring layer before the completion of the molecular orientation of the film during the filming period. CONSTITUTION:Before the completion of molecular orientation, or before a film is stretched toward one or both directions for orientation, a coloring layer composition is coated on the film. In the case of biaxially oriented polyethylene terephthalate film, for example, the most preferable coating time of the coloring layer is during the preheating time. When coating the coloring layer by a solvent method, the coating is preferably made after the primary stretching and before preheating. When the polymer film is stretched after the coating of coloring layer, the final thickness of the coloring layer after being stretched is controlled preferably to 15mum or less.

Description

[Detailed description of the invention] [Technical field] The present invention relates to a method for manufacturing a thermal transfer recording medium.

More specifically, the present invention relates to a method for manufacturing a thermal transfer recording medium, which can reduce manufacturing costs and provide a thermal transfer recording medium having a coloring material layer that does not easily peel off.

[Prior Art] A thermal transfer recording medium has been conventionally used as a recording medium for transferring and forming an image on a recording sheet such as a sheet of paper by a thermal printer, a thermal facsimile, or the like. This thermal transfer recording medium has at least one coloring material layer on a support, and the coloring material layer is, for example, a layer containing a dye such as a pigment and a heat-melting substance. There is. In addition, films with excellent dimensional stability are used as the support in order to obtain good reproducibility of the dye transfer image obtained from the coloring material layer coated on this surface. When the support is, for example, a polyethylene terephthalate film, a biaxially stretched film is used to obtain its =j゛ stability.

A thermal transfer recording medium is manufactured by applying a coloring material layer to such a support with excellent dimensional stability by a hot melt method or a solvent method.

Coating a coloring material layer on such a manufactured film support is performed in a coating process that is completely different from the film forming process of the film support, resulting in an increase in manufacturing costs. is inviting.

On the other hand, thermal transfer recording media require adhesion between the support and the coloring material layer coated on the support to prevent film peeling during handling. According to the conventional manufacturing method, there was also the problem of delamination.

[Object of the Invention] An object of the present invention is to provide a method for manufacturing a thermal transfer recording medium that can significantly reduce manufacturing costs.

Another object of the present invention is a method for producing a thermal transfer recording medium, which improves the adhesion of a coloring material layer to a film support and prevents film peeling during handling and scumming during transfer recording. The goal is to provide the following.

Other objects of the invention will become apparent from the following description of the specification.

[Summary of the Invention] As a result of intensive research, the present inventors have found that the above object can be achieved by coating a coloring material layer on a stretched polymer film before the molecular orientation of the film is completed during film production. The inventors have discovered that this can be achieved, and have developed the present invention.

[Structure of the invention] The present invention will be described in further detail below.

The polymeric films of the present invention are formed from any hydrophobic synthetic polymeric material and are 1-process stable films after orientation and heat curing. Suitable polymeric materials include polyesters such as polyethylene terephthalate, copolyesters and polycarbonates. A preferred polymeric material is polyethylene terephthalate.

The polymeric film must be dimensionally stable under the conditions of thermal transfer so that the dye transfer image obtained from the dye layer provided on the film support according to the present invention is not distorted. Although some uniaxially oriented polymer films are sufficiently dimensionally stable, polymer films are commonly oriented biaxially to achieve the desired dimensional stability. When a polyethylene terephthalate film is used, dimensional stability is generally achieved by biaxial orientation.

Generally, biaxially oriented polymer films are oriented by first stretching in the longitudinal direction and then in the transverse direction. The biaxially oriented film is then heat set by heating while restricting the film against longitudinal and transverse shrinkage. Additional stretching in the longitudinal direction can also be used to improve the longitudinal tensile strength before or after hot curing. A method to improve longitudinal tensile strength is to first stretch in the transverse direction and then in the longitudinal direction.

Yet another method of biaxial orientation of the film is simultaneous longitudinal and transverse stretching.

All of the above methods of biaxially orienting polymeric films are known, and any of these methods may be used in practicing the present invention. Molecular orientation is carried out by stretching at a temperature below the softening point of the film but above its secondary transition temperature.

A typical method used in the present invention for biaxially orienting a polyethylene terephthalate film cast onto a drum and rapidly cooled to below 80'O is as follows.

That is, the film is stretched longitudinally between two sets of fast and slow nip rolls or capstan rolls giving a stretching ratio of 2.5:1 to 4.0:l at a temperature in the range of 80-100'0, then 80-120' Stretching in the transverse direction at a temperature in the range of 0 and at a higher temperature than that used for longitudinal stretching. The stretching ratio in the lateral direction is 2.5:
1-4.0: Performed on I tenter. The film is then heated at a temperature ranging from 150 to 250'O.
Heat set by heating, preferably while holding the film in a tenter device, with limited shrinkage in both directions for ~5 minutes. Afterwards, heat set the film as needed.
1.5:1 to 8.0 at temperatures ranging from oo to 220'O:
It is also possible to stretch in the longitudinal direction using a stretch ratio of 1.

According to the present invention, the colorant layer composition is applied before the molecular orientation is completed, ie, before the unidirectional or bidirectional stretching operation used to orient the film. Before orientation takes place, for example in the case of biaxially oriented polyethylene terephthalate films (
1) applying a colorant layer composition to the polymeric film after it has been cast on a quench drum and before the first stretching in the longitudinal or transverse direction (usually the former); It is applied after the next stretching and before preheating, [3] it is applied during preheating, [4] or it is applied after the second stretching of the biaxially oriented film. Among these, the most preferable application time is [3]
[2], [1] and [4] are preferred in this order. In addition, when coating a coloring material layer by a solvent method, it is preferable to carry out said [2].

Suitable techniques for applying colorant layers to polymeric films are known in the art, and these techniques can also be used in the present invention. For example, the coloring layer may be formed by hot-melt coating with a composition containing at least a colorant/hainder and a softener, or by solvent coating with a coating solution obtained by dissolving or dispersing the composition in an appropriate solvent. 15. The following layers are included.

As a method for applying the coloring material layer of the present invention, any known technique such as a reverse roll coater method, an extrusion coater method, a gravure coater method, etc. can be employed.

When the polymer film is stretched after coating, the coloring material layer of the present invention is preferably applied so that the final thickness after stretching is 15 mm or less. In addition, in order to prevent the clips that sandwich the polymer film from being contaminated by the colorant of the coloring material layer during the lateral stretching process, etc., 2.0 to 3.5 cm of each end of the polymer film is coated on both sides of the polymer film. It is preferable that no coloring material layer be applied.

As the binder, materials that can be easily melted by heat are preferably used, such as waxes such as carnauba wax, auricule wax, and microcrystalline wax, or resins such as low-molecular-weight sewn polyethylene and vinyl polystearate.

Also, for example, polyvinyl acetate, polystyrene, styrene-
Polymer compounds such as butadiene copolymers, cellulose esters, cellulose ethers, and acrylic resins are also suitably used as binders together with the above heat-meltable substances. As softeners, vegetable oils such as castor oil, linseed oil, and olive oil, animal oils such as whale oil, and mineral oils are preferably used. As the coloring agent, various dyes or pigments that have been widely used in the art can be used without any particular restrictions. For example, it can be dissolved or dispersed in the binder in the coloring material layer when melted, and has a color.
Substances that are solid at room temperature are used as colorants, and various dyes or pigments known in the art can be used.

Specifically, the following can be mentioned. That is, as the yellow pigment, Kayalon Polyester Light Yellow 5G-3
(11honkayaku), Oil Yellow 5-7 (white clay), Eizenspiron GRH Special (Hodogaya), Sumiplast Yellow FG (Jumikata), Eizenspiron Yellow G
RH (Hodogaya), etc. are preferably used. As the red pigment, Diaceriton Fast Red R (Mitsubishi Kasei),
Dianex Brilliant Tread BS-E (Mitsubishi Kasei), Sumiplast Tread FB (Sukkata), Sumiplast Tread HFG (Sukkata), Kayalon Polyester Pink RCL-E (Nippon Kayaku), Eisenspiron Red G
EH Special (Hodogaya), etc. are preferably used. As blue pigments, Diaceritone Fast Brilliant Blue R (Mitsubishi Kasei), Dianic Sprue EB-E
(Mitsubishi Kasei), Kayalon Polyester Flue B-3F
Conch (Nippon Kayaku), Sumiplast Blue 3R (Jumikata)
, Sumiplast Blue 〇 (Jukukata), etc. are preferably used. In addition, as a yellow pigment, Hansa Yellow G (3)
, Taldrazine Lake, etc. are used, red pigments include Brilliant Carmine FB-Pure (111 positive pigment), brilliant carmine 6B (111 positive pigment), Alizarin Lake, etc., and blue pigments include Cerulean Blue, Sumika, etc. Blintcyanine Flu G N
-0 (Shukukata), phthalocyanine blue, etc. are used, and as the black pigment, carbon black, oil black, etc. are used. In addition, metal particles or metal oxides may also be used.

These binders, softeners, and colorants are mixed in proportions of 10 to 85 parts, 0.5 to 5 parts, and 2 to 25 parts, respectively, with respect to 100 parts (parts by weight, same hereinafter) of the total amount of the heat-melting coloring material layer. It is preferable to do so, and in that case, the melt transferability of the formed heat-melting color material layer is extremely good.

In the present invention, a subbing layer may be provided to prevent the polymer film from reacting with the solid colorant in the color material layer during the stretching process of the polymer film.

0 Examples of the undercoat layer include silicone resin, melamine resin, polyvinacetal resin, polyethylene, polyvinyl chloride,
Examples include polyvinylidene chloride, fluororesin, etc., and the subbing layer can be applied in the same manner as the coloring material layer coating technique prior to coating the coloring material layer.

[Effects of the Invention] According to the present invention, the coloring material layer is coated on the film before the molecular orientation of the film is completed during the production of the stretched polymer film, so that the above-mentioned objectives can be achieved. [l]
, [2], [3]] When coating the coloring material layer, the desired thin coloring material layer can be obtained even if the coating is applied in a thick range where the film thickness is relatively easy to control. This effect can also be obtained.

[Example] Examples are given below, but the embodiments of the present invention are not limited thereto.

Example 1 Polyethylene terephthalate is melt-extruded from a slot die onto a rotating drum and formed into an amorphous shape 1! It was quenched to E. The amorphous film is rolled in the longitudinal direction between slow and fast rollers at a temperature of about 80°C.
: Stretched at a stretching ratio of 1. The film was then coated with a heat-melting colorant layer composition having the composition ratio shown below at about 50°C using a reverse roll coater.

[Thermofusible coloring material layer composition]

Carnauba wax 8 parts by weight Wax (H stone microwax +55) 8 parts by weight Olive oil 1 part by weight Carbon black 3 parts by weight Toluene 80 parts The dry film thickness of the coloring material layer was 15 IL.

The film coated with the colorant layer was then passed through a tenter oven where it was stretched in the transverse direction at a stretch ratio of approximately 3:1 while being heated to +00°C. The film was heat set in a tenter oven at a temperature of about 200°C without restricting longitudinal and transverse shrinkage.

In this way, a heat-sensitive transfer recording medium was obtained, in which a coloring material layer 5 μL thick was coated on a 6 pL-thick polyethylene terephthalate film support.

2 Example 2 Polyethylene terephthalate was melt extruded from a slot die onto a rotating drum and quenched to 7 g of amorphous shape. The amorphous film was stretched in the longitudinal direction between slow and fast rollers at a temperature of about 90°C with a draw ratio of about 4:1. Next, this amorphous film is subjected to a preheating process immediately before entering the transverse stretching process, and at this stage, the meltable coloring material layer composition having the following composition is coated at IO°C using a reverse roll coater to a thickness of 16 mm. Coated. The coated film was then stretched in the transverse direction in a tenter at a stretch ratio of about 4=1 and heat set at a temperature of about 200° C. while limiting shrinkage in the longitudinal and transverse directions. After cooling, the film sample was rolled up on a roller.

In this way, a film support with a thickness of 5.5"-
A heat-sensitive transfer recording medium was obtained in which a heat-melting coloring material layer having a thickness of 4 pL was coated on the film.

[Thermofusible coloring material layer composition]

Paraffin (Paraffin Solid 32030, manufactured by Kanto Kagaku Co., Ltd., melting point 62-64°C) 40 parts by weight 3 carnauba wax (melting point 82-88°C) 30 heavy seam wax (Sun wax + 7 IP).

Manufactured by Sanyo Kasei Co., Ltd. (softening point: 105°C) 15 parts by weight Carbon black 15 parts by weight When a thermal transfer recording test was conducted on each sample obtained in Examples 1 and 2 using a thermal heft (driver equipped type), '' A dye image having the same transfer density as when the two colorant layer compositions were applied on the same heat-set polymer film was formed on the recording sheet (plain white paper with Beck smoothness of 500 seconds). Obtained.

Patent applicant: Konishiroku Photo Industry Co., Ltd. Agent patent attorney board 1” rented space (1 other person)

Claims (1)

[Claims] 1. A method for producing a heat-sensitive transfer recording medium, which comprises coating a coloring material layer on a stretched polymer film before the molecular orientation of the film is completed during film production.