JPS62208933A - Polyester film for heat sensitive transfer material - Google Patents

Abstract

PURPOSE:To prevent a sticking phenomenon, by making the titled film contain specific higher alphatic monocarboxylic acid and/or its metallic salt. CONSTITUTION:At least a kind of a higher alphatic monocarboxylic acid or its metallic salt whose number of carbon atoms is more than 18 is made to contain within a 0.005-2wt% polyester film. The polyester is mainly polyethylene terephthalate and polyethylene-2,6-naphthalate. As an embodiment of the monocarboxylic acid or its metallic salt, capric acid, lauric acid, linolic acid, an acid mixture containing those acid and synthetic monocarboxylic acid which possesses the number of atoms of more than 18 can be mentioned. As the metal species, alkali and/or alkali earth metal is mentioned. The polyester film obtained in this manner is extremely superior in slidable properties and generation of a sticking phenomenon is prevented.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a polyester film for thermal transfer materials.

More specifically, the present invention relates to a polyester film for a thermal transfer material that prevents fusion (stick phenomenon) between the thermal transfer material and a thermal head during printing and that runs smoothly.

[Conventional technology]

In recent years, as office automation has progressed, various recording methods have been developed, and among these, thermal recording methods are attracting attention because they generate less noise during printing and are easy to operate.

Normally, a thermal recording method is used in which a thermal head is brought into direct contact with thermal recording paper containing a special coloring compound. In this method, the operability of the thermal recording device,
It has excellent maintainability, but the recording paper tends to discolor due to heat or heat, so it is great for long-term storage of records! ! That's a problem. Recently, the thermal transfer recording method has been attracting attention and has begun to be widely used as a method that takes advantage of the advantages of the thermal recording method and eliminates the above-mentioned disadvantages. Thermal transfer recording method is used in various mallet printers because it can print on plain paper, has excellent long-term storage stability, and has excellent print quality. Examples of printers include computer printers, word processor printers, video printers, label printers, still video camera printers,
Examples include facsimiles.

Furthermore, computers have made remarkable progress in recent years, making it easier to display color graphics, and printers have entered the age of color.

In this method, a heat-sensitive transfer material is used which is composed of a base material and a heat transfer layer coated on the surface of the base material. When printing, the recording paper (generally plain paper can be used) is brought into contact with the thermal transfer layer of the thermal transfer material, pressure is applied, the thermal head is brought into contact with the opposite side of the base material, and a pulsed signal current is applied to the head. υ, heat the thermal head. In this way, a heat-melting ink layer is transferred only from the thermal transfer layer of the heated portion, and a sublimation ink is sublimated.
Transfer and record on recording paper. Normally, a heat-melting ink layer is easily transferred to recording paper at an ink temperature range of 60℃ to 1-〇〇℃, and a sublimable ink layer is sublimated and transferred at an ink temperature range of 70℃ to -〇〇℃. do. Generally, the method using the former is called the heat-fusion type thermal transfer method.

The method using the latter is called a sublimation type heat-sensitive transfer method.

In the case of the heat-melting type thermal transfer method, for solid black printing, a thermal transfer material containing carbon black is used in the ink layer.
Yellow for colorization.

A method was adopted in which the three primary colors were thermally transferred onto the same recording paper three times, once for each color, and the three primary colors were superimposed.

On the other hand, the great feature of the sublimation type thermal transfer method is that it can easily produce one gradation, that is, the amount of sublimated ink can be easily controlled by the amount of heat of the thermal head. If you want to make a color darker, you can increase the applied voltage or lengthen the current pulse application time, and if you want to make one color lighter, you can increase the voltage by lowering the applied voltage or shortening the current pulse application time. Taking advantage of the fact that this gradation can be easily produced, this method is used for color printing, especially for color printing of precise figures and photographs.
Similar to the heat-melting type, this method involves preparing heat-sensitive transfer materials for each of the three primary colors of yellow, magenta, and cyan, and performing heat-sensitive transfer once for each color, for a total of three transfers. In the case of the sublimation type heat-sensitive transfer method, as mentioned above, in order to make one color darker, it is necessary to increase the amount of heat of the head, and the heat-sensitive transfer material is subjected to a higher temperature than the heat-melting type. When using sublimation ink in the thermal transfer method, a special image-receiving layer is sometimes provided on the recording paper to ensure color stability and maintainability, but in general, the thermal transfer method uses plain paper. Since it can be easily recorded, the disadvantages of the thermal recording method can be eliminated.

Conventionally, capacitor paper has been used as the base material for this thermal transfer material, but its strength is low.

It has been proposed to use a thin film of plastic as a base material because it is easily torn, it is difficult to print at high speed (high-speed printing is sharp), and reducing thickness unevenness is a national problem.

[Problem that the invention seeks to solve]

By the way, when a plastic film is used as a base material, the stick phenomenon described below occurs, and its use 1c causes a serious problem.

In other words, during recording, when the surface temperature of the thermal head exceeds the melting point of the base plastic film, the stick phenomenon occurs in which the film that comes into contact with the thermal head fuses to the thermal head, which prevents the feeding of the thermal transfer material. occurs. The stick phenomenon causes the recording to lose its sharpness, makes a lot of noise when the fused film is forcibly peeled off, and if it is severe enough, it can cause the machine to stop running and cause operational problems. The stick phenomenon is
In particular, it is often found in sublimation type heat-sensitive transfer materials where the temperature of the thermal head is high.

As a technique for preventing such a sticking phenomenon, attempts have been made to form a coating film by applying a coating solution containing a certain specific compound to the surface opposite to the surface on which the thermal transfer layer is to be provided.

However, these proposals have the problem of requiring a coating means to form a coating film, which increases the cost of preparing the thermal transfer material.

On the other hand, in Japanese Unexamined Patent Publication No. 1.0-10 Da3ri No. 3.

It has been proposed to incorporate an ester wax into polyester. However, the sticking phenomenon?
However, the reduction in the Masatsu coefficient was not sufficient to prevent this problem, and a modification A was required.

[Means for solving problems]

In order to meet the above-mentioned needs, the present invention has been made as a result of intensive studies and it has been discovered that the problems can be solved by containing a certain specific higher aliphatic monocarboxylic acid and/or its metal salt. It's a friend that I've reached.

That is, the gist of the present invention is as follows.

(At least one type of higher aliphatic monocarboxylic acid having 13 carbon atoms or more or its gold base, o, o o s N
A polyester film for a heat-sensitive transfer material containing 1 amount of 3 in a polyester film.

The present invention will be explained in more detail below.

The polyester used in the present invention is mainly polyethylene terephthalate and polyethylene-6-naphthalate. Other polyesters include polypretin terephthalate, polybutylene dibenzoate, homopolyesters such as polyesters of bisphenol A and terephthalic acid or isophthalic acid, and polyethylene terephthalate. Recall, phthanediol, xylylene glycol, bisphenol A diethylene glycol, polyethylene glycol, polytetramethylene glycol, polypropylene glycol, adipic acid, sebacic acid, phthalic acid, isophthalic acid, u, &-naphthalene dicarboxylic acid, p-oxyethoxybenzoic acid A copolymer of acid, glycolic acid, etc. may also be used. In addition, polypropylene terephthalate, polybenzene bibenzoate), J, j-
Polyester of bis-(p-oxyphenyl)pentane and terephthalic acid% Co, -polyester of bis(,7-methyloxyphenyl)propane and terephthalic acid, U, Corpis(p-oxyphenyl)pentane and isophthalic acid, Examples include polyesters of terephthalic acid, copolyesters of ethylene terephthalate and ethylene isophthalate, and copolyesters containing sepagate, adipate, etc., but needless to say, they are not necessarily limited to these.

Specific examples of higher aliphatic monocarboxylic acids having 18 or more carbon atoms or metal salts thereof in the present invention include capric acid, lauric acid, stearic acid, nonadecane, arachidic acid, behenic acid, melisin I! 1121 Carnaubic acid,
Lignoceric acid, cerotic acid, montanic acid, hentriaconic acid, hetroserine, olein rII1. Erucic acid, linoleic acid and acid mixtures containing these and carbon number/
Examples include synthetic monocarboxylic acids of j or more.

Metal salts include alkali and/or alkaline earth metals such as lithium, sodium, potassium, barium,
Examples include magnesium, calcium, strontium, etc., and preferred metal species are alkali metals with excellent thermal stability.

%, preferably sodium salt.

In addition, when the number of carbon atoms of the aliphatic monocarboxylic acid or its metal salt is IT droplets, bleed-out to the film surface is severe and adhesion to the wax layer is significantly inferior. In order to prevent bleed-out and improve adhesion to the wax layer, a synthetic monocarboxylic acid having 3 or more carbon atoms or a conductor thereof is preferred.

The content of the higher aliphatic monocarboxylic acid or its metal salt is 0.00 j to 100 parts by weight of polyester.
It must be by weight, preferably FiO, 0/~/S, more preferably o, oz~O,S weight %.

If the above content is less than 3 by weight, the flatness and slipperiness of the film will hardly be obtained, υ, and if it exceeds the weight by weight S, bleed-out to the film surface may occur. This is undesirable because the adhesiveness with the wax layer becomes extremely poor.

On the other hand, the melting point of the higher aliphatic monocarboxylic acid or its metal group is preferably 70°C or more and 160°C or less. More preferably, the melting point is 900 or more and 2oo'c or less.
If it exceeds 0.degree. C., the polyester will not melt and will not be dispersed evenly during extrusion production, while if it is less than 0.degree. C., it will cause thermal deterioration during film production, which is not preferable.

In addition to the higher aliphatic monocarboxylic acid and its gold JF4 salt, it is of course preferable to coexist with known particles capable of forming protrusions in the present invention. In the present invention, methods for forming protrusions include a method in which a phosphorus compound is applied to a metal compound dissolved in the reaction system during polyester production to precipitate fine particles, a so-called precipitated particle method, and a method in which inorganic fine particles are added. Either method can be adopted.

Examples of the inert fine particles include kaolin, Merck, magnesium carbonate, calcium carbonate, barium carbonate,
Calcium sulfate, barium sulfate, lithium phosphate, calcium phosphate, magnesium phosphate, aluminum oxide, silicon oxide, titanium oxide, lithium fluoride and Oa.

! Metal compounds selected from terephthalates such as 3a, Zn, and Mn may include carbon black and the like. However, it is not limited to these. The shape of this inert compound may be spherical, blocky, or flattened, and there are no particular limitations on its hardness, specific gravity, or the like.

Incidentally, in producing the polyester film of the present invention, there is no problem in containing commonly used stabilizers, colorants, antistatic agents, pigments, etc.

In addition, the polyester film in the present invention is a uniaxially oriented film and a biaxially oriented film, and has easy sliding properties.

Film b is preferred in terms of excellent thickness uniformity, and biaxially oriented film is particularly preferred.

Next, the method for manufacturing the polyester film of the present invention will be explained. First, a polyester polymer I material containing a higher aliphatic monocarphonic acid or a metal salt thereof and a predetermined amount of additive particles and/or precipitated particles such as carbonic carkaolin and silica is dried. Here, as a method for incorporating higher aliphatic monocarboxylic acid or its metal salt into polyester, 2! It may be added during the polymerization reaction or after the polymerization reaction is completed.

As for the method of adding it after the polymerization reaction, it may be mixed with the polyester and extruded, or it may be added during extrusion of the polyester. In addition, the additive amount may be directly added within the above-mentioned content range, or it may be added in advance in a large amount so as to have a higher concentration than the above-mentioned content, and then diluted with polyester. Alternatively, the content may be within the above content range.

The dried polymer obtained as shown in the figure above is melt-extruded by a known method and, for example, cooled and solidified on a casting drum by an electric contact method or the like to obtain an unstretched film or a non-oriented film.

In addition, the unstretched film may be biaxially oriented by a known method using rolls, a tenter, or the like, or by a known biaxial stretching method such as further longitudinal stretching after the biaxial stretching. obtain.

〔Effect of the invention〕

The thus obtained polyester film had extremely excellent slipperiness, which had never been achieved before, and when used as a thermal transfer recording medium, the occurrence of the sticking phenomenon was prevented, and the film was extremely good. Furthermore, when a high melting point wax was used in the transfer layer of the thermal transfer type, it had excellent adhesion to the wax compared to conventional films.

〔Example〕

EXAMPLES The present invention will be specifically explained below with reference to Examples, but the present invention is not limited to these Examples as long as the gist of the invention is not exceeded.

Note that the characteristics of the film in the present invention were evaluated by the method shown below.

(1) Film-film dynamic friction coefficient CF/F-μa
) This method was modified based on the method of ASTM D-/It Cool 3 so that it could be measured using a tape-shaped sample, and the measurement was carried out in an atmosphere at a temperature of 3° C. and a humidity of 30%. The measurement conditions were: tensile speed -〇 tm/min, chart speed 1/min, loading technique g103.911, and the sample size was width/jm, length/! The one from rOwm was used.

(2) Evaluation of thermal transfer recording medium A heat-fusible coloring material layer having the following composition was coated on a support using a hot-melt coating method using a heated roll to obtain a thermal transfer recording medium sample with a heating element density of 1 ff dot /, The results were loaded into a prototype printer equipped with a thin-film line thermal head and recorded on plain paper.

The applied energy at this time was /, OmJ/aot. In terms of printing quality, good printing quality was marked as ○, poor printing quality was marked as ×, and the mark in between was marked as Δ.

(Composition) @Amount ratio) Ester wax 3S Carnauba wax 3Q Polytetrahydrofuran IQ carbon black L-cosilicon oil 3 Also, after pasting a cellophane adhesive tape commercially available from Nichiban Co., Ltd. on the transfer surface of the above thermal transfer recording medium and peeling it off to0. Evaluation was made based on the remaining adhesion area of the transfer layer.

The criteria for evaluation are as follows.

If the index is 3 or more, it is sufficient for practical adhesive strength.

Example 1~Example! Comparative Example 1 A polyester polymer composition having the composition shown in Table 1 was dried and extruded into a sheet using an extruder at -10°C, and an amorphous sheet was formed using an electrostatic cooling method. The amorphous sheet is first 2.9 times t and tm in the longitudinal direction, and then 7S in the same direction.
After stretching 63 times at 100°C, the film was stretched in the width directions e and o at 100°C and heat-set at SO 0 C to obtain a biaxially stretched polyester film with a thickness of 6 μm. Table 1 shows the physical properties of these films and their properties as thermal transfer recording media.

Table 1 shows that the film of the present invention has excellent slip properties and is suitable for use as a polyester film for heat-sensitive transfer materials.

Here, compounds (1), (2) and (3) are as follows.

Compound (1) Compound (2) HH HE　　　H

Claims (2)

[Claims] (1) At least one selected from higher aliphatic monocarboxylic acids having 18 or more carbon atoms and metal salts thereof, at a concentration of 0.00
A polyester film for thermal transfer material containing 5 to 2% by weight of polyester film. (2) A polyester film for a thermal transfer material according to claim 1, wherein the higher aliphatic monocarboxylic acid having 18 or more carbon atoms or its metal salt has a melting point of 100°C or more and 260°C or less. .