JPH01105786A - Thermal transfer film - Google Patents

Abstract

PURPOSE:To enable printing to be performed a lot of times, by establishing a primer layer composed of an acrylate polymer containing a specific amount of a monomer of a glass transition point of -20 deg.C max. of a polymer composed of a specific uniacrylate on a film base material. CONSTITUTION:A primer layer composed of an acrylate polymer having 50wt.% min. of one kind or more kinds of monomers of a glass transition point of -20 deg.C max. of a polymer composed of uniacrylate expressed by the formula is established on a base material film and further, a thermal fusing ink layer is established thereon to form a thermal transfer film. Ethylacrylate (-24 deg.C), n-prophylacrylate (-48 deg.C), etc. are exemplified as a monomer. Additives of polymers, petroleum resins, etc. which are combined according to necessity in addition to a low melting point resin and a coloring agent are contained in the ink layer.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a thermal transfer film that is used in thermal transfer recording type printers, and particularly allows multiple printings.

(Prior art) Thermal transfer recording method involves placing a thermal transfer film, which has a heat-melting ink layer on a base film, on paper such as plain paper, and applying heat from a thermal head from the back side of the heat-melting ink. (hereinafter abbreviated as ink) is transferred onto paper to record prints.The printers used are lightweight, compact, noiseless, and have excellent operability and maintainability, and have recently become widely used. ing.

However, the thermal transfer films currently available on the market only have an ink layer made of a binder, colorant, resin, etc. directly on a base film, and therefore have the following drawbacks. In other words, in one transfer, the ink layer in the recording area is completely transferred without remaining on the base film, and if it is a so-called one-time product that cannot be used more than once, the printing and recording cost is high and the heat transfer film is This increases the number of replacements and takes time and effort.

On the other hand, there are many techniques already disclosed for thermal transfer films that can be used multiple times, and one such technique is a method in which an adhesive layer is interposed between a base film and an ink layer.

As such an adhesive layer, polyester resin, vinyl chloride
Vinyl acetate copolymer, acrylic resin, vinyl chloride resin (
JP-A No. 55-105579), polyamide resin (
JP-A-56-11 (JP-A-5193), polyvinyl butyral resin, epoxy resin (JP-A-57-36698), saturated linear polyester resin (JP-A-59-969)
No. 92), ethylene-alkyl acrylate copolymer (Japanese Patent Application Laid-open No. 127192/1983), and the like are disclosed.

However, the resins used in these adhesive layers have strong adhesion to the base film, but weak adhesion to the ink layer.
Even when such resins are used as an adhesive layer, they tend to peel off at the interface between the ink layer and the adhesive layer during printing, and there is no material that can be used for printing many times.

(Problems to be Solved by the Invention) The present invention has been made in view of the above situation, and it is possible to strengthen the adhesiveness between the base film and the ink layer so that the ink layer can be attached to the base film during one printing. It is an object of the present invention to provide a thermal transfer film that can be printed multiple times with good quality without causing peeling of all layers.

(Means for Solving the Problems) Therefore, as a result of extensive studies, the present inventors found that the formula %formula%) (1) and the unit represented by the formula (1) were formed on the base film. Glass transition point (hereinafter abbreviated as Tg) of a polymer made of monoacrylic acid ester
A primer layer made of an acrylic acid ester polymer containing 50% by weight (hereinafter referred to as %) or more of one or more monomers having a temperature of -20°C or less is provided, and a heat-melted layer is further provided on the primer layer. The inventors of the present invention discovered the new fact that a thermal transfer film provided with a magnetic layer can be printed many times, leading to the completion of the present invention.Hereinafter, the present invention will be explained in detail.

The monomers contained in the acrylic ester polymer contained in the primer 1 of the present invention and having a Tg of 120°C or less of the polymer consisting of a single acrylic ester represented by the formula (1) include: Ethyl acrylate (-24℃), n-propyl acrylate (-48℃), n-butyl acrylate (-65℃), inbutyl acrylate, t (-40℃)
(°C), n-hexyl acrylate (-75°C), n-octyl acrylate (-95°C), and 2-ethylhexyl acrylate (-85°C).

Such a monomer can be used in combination with 1alt or more to form a polymer, but the amount contained in the polymer is 50%.
If it is less than 50%, the adhesive force with the ink layer will decrease, and as a result, it will not be possible to print multiple times.

Furthermore, along with such a monomer, a monomer represented by the formula % formula % (2) and having a Tg of a polymer consisting of a single monomer represented by formula (2) of 120°C or higher is copolymerized. It can be used as The seven acids represented by formula (2) include acrylic acid (106°C), methacrylic acid (185°C)
, methyl acrylate (8°C), methyl methacrylate (103°C), ethyl methacrylate (62°C), n-
Propyl methacrylate (55°C), inpropyl acrylate (-6°C), n-butyl methacrylate (17
), 5ec-butyl acrylate (-17°C), inbutyl methacrylate (48°C), tert-butyl acrylate (43°C), tert-butyl methacrylate (107°C), n-hexyl methacrylate (-5°C) )
, 2-ethylhexyl methacrylate (-10°C), dodecyl acrylate (2°C), cetyl acrylate (3
5°C), acrylonitrile (96°C), 2-hydroxyether acrylate (-io°C), 2-bitrotidiethyl methacrylate (55°C), hydroxypropyl methacrylate (70°), acrylamide (100°C).
), vinyl acetate (27°C), glycidyl methacrylate (45°C), and the like.

The monomer represented by the formula (2) can be copolymerized with the monomer represented by the formula (1) in combination of one or more types, but the polymer contained in the copolymer is 0 to 40%. %, and if it exceeds 40%, the adhesive strength with both the ink layer and the base film tends to decrease, and as a result, it becomes impossible to print multiple times.

The above acrylic polymer has a viscosity of 10 to 100°000 cps (B
The temperature is preferably within the range of 20°C (as measured by a mold accuracy meter). If the viscosity is less than 10 cps, the cohesive force is weak and the adhesive force between the base film and the ink is low.
If it exceeds ps, the solubility in the solvent is low and the workability is poor.

The proportion of such a polymer in the primer layer must be 50% or more; if it is less than 50%, the adhesion to both the ink layer and the base film decreases, resulting in failure to print multiple times.

In addition to the above-mentioned polymers, other polymers, softeners, etc. can be appropriately selected and used in the primer layer, if necessary, within a range of 50% or less of the primer layer.

Other polymers include ethylene-ethyl acrylate copolymer, ethylene-vinyl acetate copolymer, ethylene-vinyl acetate-unsaturated acid copolymer, saponified ethylene-vinyl acetate copolymer, and (meth)acrylic acid ester. Grafted natural rubber, acrylonitrile-butadiene copolymer, polyamide, polyester, epoxy resin, phenolic resin,
In addition to mepmine resin and urea resin, various petroleum resins (terpene phenol resin, alkyl phenol resin, rosin acid, rosin acid ester type, coumaron-indene type, other aliphatic type, aromatic type, etc.) can be mentioned.

As the softening agent, organic acid esters such as phthalic ester acids and adipic esters, phosphoric esters, epoxy-based plasticizers, and other substances that are liquid or semi-solid at room temperature are used.

The properties of the primer with this composition are as follows: When made into a 15% toluene solution, the viscosity is 10 to 50°000 cps (B
The temperature is preferably within the range of 20°C (as measured by a mold accuracy meter). When the viscosity is less than 10 cps, the cohesive force is weak and the adhesive force between the ink and the base film is low;
If it exceeds ps, the solubility in the solvent may be low, and the coating workability may be poor.

A solution coating method is mainly adopted as a method for forming the primer layer according to the present invention on a base film, but it may also be applied as an emulsion liquid. The solvent or dispersion medium must be removed by drying after coating.

The thickness of the primer layer is preferably 0.03 to 3 μm. 0
．． If the thickness is less than 0.03 μm, the adhesive force with the ink layer and/or the base film will be low, and the effect of the present invention will be lost9, and if the reverse VC is greater than 3 μm, the printing sensitivity will decrease.

The ink layer provided on the primer layer of the present invention is not particularly limited, but the ink layer preferably used will be described.

In addition to a low melting point resin and a colorant, the ink layer of the present invention contains additives such as polymers, petroleum resins, fillers, lubricants, surfactants, and softeners, which are blended as necessary.

As the low melting point resin, paraffin wax, microcrystalline wax, carnauba wax, ceresin wax, oxidized wax, ester wax, polyethylene wax, other natural waxes, synthetic waxes, etc. are used.

Carbon black, organic pigments, inorganic pigments, dyes, etc. are used as the coloring agent.

Further, as additives to be added as necessary, appropriate ones can be selected from those described below.

Examples of polymers include ethylene-acrylic acid copolymer, ethylene-alkyl acrylate copolymer, ethylene-vinyl acetate copolymer, ethylene-vinyl acetate-unsaturated acid copolymer, saponified ethylene-vinyl acetate copolymer, and polyester. Selected from isobutylene, butyl rubber, polybutadiene, polybutene, polyimprene, natural rubber, etc.

In addition to the petroleum resins that can be contained in the primer layer described above, a variety of petroleum resins such as aliphatic resins, terpene resins, and dicyclopentadiene resins are used.

Fillers include magnesium oxide, magnesium carbonate,
Magnesium hydroxide, aluminum oxide, aluminum hydroxide, barium sulfate, vermiculite, perlite, acid clay, activated clay, diatomaceous earth, dolomite, mica,
Amorphous materials such as sericite, bentonite, kaolin, clay, talc, calcium carbonate, graphite, and various metal powders,
It can be selected from shapes such as spherical, scaly, and spindle.

As the lubricant, polyhydric alcohol ester, higher alcohol, higher fatty acid, fluorocarbon, higher fatty acid amide, higher fatty acid ester, fatty acid higher alcohol ester, higher aliphatic amine, etc. are used.

The surfactant is selected from various anionic, cationic, nonionic, and amphoteric surfactants.

Softeners include organic acid esters such as phthalate esters and adipic esters, phosphate esters, epoxies, other plasticizers, oily substances such as mineral oil, vegetable oil, animal oil, and castor oil, liquid rubber, and Vaseline and other liquid or semi-solid substances at room temperature are used.

A method for applying a small amount of ink, such as a low melting point resin, a colorant, and additives blended as necessary, onto a base film on which a primer layer has been previously provided is either a solution method or a hot melt method. can also do this.

When a solvent is used, it is necessary to dry and remove the solvent after coating.

The thickness of the ink layer to be applied is preferably in the range of 5 to 20 μm, and if it is less than 5 μm, the printing density will decrease from the second time onwards, and if it is more than 20 μm, the printing energy of the ink will be too high.
Since 1/kVC is required, the ink layer may not be sufficiently melted during printing, and satisfactory printing may not be possible.

The base film used in the present invention may be any heat-resistant film, and includes plastic films such as stretched polyester, polyamideimide, and polyimide, and papers such as capacitor paper and glassine paper. The thickness can be applied within the range of 1.0 to 20 μm.

Thin ones are easily torn, and those with a thickness of 20 μm or more require large printing energy and are not practical.

(Function) The reason why the thermal transfer film of the present invention enables printing many times is presumed to be as follows.

The ink layer uses heat to melt the ink or dry the solvent during coating, and the solvent diffuses between the primer layer and the primer layer during solution coating, improving the adhesion between the ink and primer layers. At the same time, it is assumed that the polymer constituting the primer layer enters the ink layer closer to the primer layer, and the cohesive force of the ink increases as the primer layer gets closer. Therefore, at the beginning of the number of printings, the ink surface layer with weak cohesive force becomes a thin layer and is easily peeled off and transferred, and as the number of printings increases and the ink layer thickness becomes thinner, the peeling layer approaches the primer layer. Strike AM is presumed.

(Example) Next, the present invention will be explained with reference to an example. Note that all percentages are it%.

Example 1 After dissolving the following composition in toluene and coating it on a stretched polyester film having a thickness of 6 μm, the toluene was removed by drying to obtain a primer layer having a thickness of 5 μm.

Next, an ink having the following composition was dissolved in toluene and applied on the primer layer using a wire bar, and then the toluene was removed by drying to obtain a thermal transfer film having an ink layer with a thickness of 10 μm.

Example 2 The following composition was dissolved in toluene and coated on a stretched polyester film with a thickness of 6 μm, and after drying, the thickness was 0.2
A primer layer of μm was obtained.

Next, an ink having the same composition as in Example 1 was dissolved in toluene and applied on the primer layer using a wire bar, and then the toluene was removed by drying to obtain a thermal transfer film with an ink layer having a thickness of 10 μm. Ta.

Example 5 The following composition was dissolved in toluene and coated on a stretched polyester film with a thickness of 6 μm, and after drying, the thickness was 1.0 μm.
A primer layer of μm was obtained.

Next, an ink having the following composition was dissolved in toluene and applied on the primer layer using a wire coater, and then the toluene was removed by drying to obtain a thermal transfer film having an ink layer with a thickness of 10 μm. .

Example 4 The following composition was dissolved in toluene and coated on a stretched polyester film with a thickness of 6 μm, and after drying, the thickness was 0.5 μm.
A primer layer of μm was obtained.

Next, an ink having the same composition as in Example 3 was dissolved in toluene and applied onto the primer layer using a wire bar, and after drying, an ink layer having a thickness of 10 μm was provided to obtain a thermal transfer film.

Example 5 On a stretched polyester film having a thickness of 6 μm, a primer layer having a thickness of 0.5 μm after drying was obtained by dissolving the following composition in toluene.

Next, an ink having the following composition was dissolved in toluene and coated on the primer layer using a wire bar, and after drying, an ink layer having a thickness of 10 μm was provided to obtain a thermal transfer film.

Comparative Example 1 After dissolving the following composition in toluene on a stretched polyester film having a float of 6 μm, a primer layer having a thickness of 1 μm after drying was obtained.

Next, a thermal transfer film was obtained by providing an ink layer with a thickness of 10 μm on the primer layer using the same ink as in Example 1 and using the same method.

Comparative Example 2 After dissolving the following composition in toluene and coating it on a stretched polyester film with a thickness of 6 μm, the dust level after drying was 1.0.
A primer layer of μm was obtained.

Furthermore, the thermal transfer films obtained in Examples 1 to 5 and Comparative Examples 1 and 2 were printed at 0.3 mj/
Dot energy was applied, and printing was attempted many times on paper with a Bekk smoothness of 200 seconds. The results are shown in Table 1.

Note that in the results shown in Table 1, printing density was expressed as reflection density (OD), and the higher this value, the more appropriate printing was performed. This numerical value is preferably 0.8 or more as a visually readable range.

Table 1 below Kuraguchi As shown in the examples in Table 1, the product of the present invention can be printed multiple times. As is clear from comparison with the comparative examples, this is because one type of monomer having a glass transition temperature of 120 degrees Celsius or lower, or a single acrylic ester represented by formula (1) Q is made possible by a thermal transfer film comprising a primer layer made of an acrylic ester copolymer containing 50% or more of acrylic acid ester, and a heat-melting ink layer on top of the primer layer. .

Note that the present invention is not limited to these embodiments, and various modifications can be made without departing from the technical idea of the present invention.

(Effects of the Invention) As explained above, according to the present invention, it is possible to provide a thermal transfer film that can be printed many times, and therefore has great industrial value.

Representative Patent Attorney Akira Hirose, Pa Procedural amendment (voluntary)

Claims (1)

[Claims] 1. There is a formula ▲a mathematical formula, a chemical formula, a table, etc. on the film base material▼(n = an integer from 2 to 9) (1), and a single compound represented by the formula (1) A primer layer made of an acrylic ester polymer containing 50% by weight or more of one or more monomers whose glass transition point is -20°C or less is provided, and A thermal transfer film characterized by having a heat-melting ink layer provided thereon.