JPH1035125A - Thermosensitive transfer recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thermosensitive transfer recording medium on which an image can be printed in the high definition mode even under severe printing environments without damaging the outstanding heat resistance and mechanical characteristic of aromatic polyamide. SOLUTION: A base film comprising aromatic polyamide and/or aromatic polyimide as main ingredients has the following two groups of protrusions, at least, on one of the faces, preferably on both faces of the base film: (1) 10<2> -10<8> pcs/mm<2> of fine protrusion with a height of 30nm or more from the plane of the film and a maximum diameter of 5nm or more, (2) 5×10<8> pcs/mm<2> or more of superfine protrusion with a height of not more than 30nm and a maximum diameter of 3nm or more. In addition, a thermosensitive transfer layer is provided on the base film to obtain this thermosensitive transfer recording medium.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to severe use conditions,
In particular, the present invention relates to a heat-sensitive transfer recording medium that has excellent durability of a printing layer even under high temperature and high stress conditions, and has excellent running properties and printing characteristics in which wrinkles and deformation do not occur.

[0002]

2. Description of the Related Art Aromatic polyamides and aromatic polyimides are useful as industrial materials because of their high heat resistance and electrical insulation. In particular, aromatic polyamides composed of para-oriented aromatic nuclei, such as polyparaphenylene terephthalamide (PPTA), provide molded articles having excellent strength and elastic modulus in addition to the above-mentioned properties due to their rigidity, and thus their utility value. Is expensive.

On the other hand, a thermal transfer recording medium basically comprises a thermal transfer layer and a base film. Conventionally, a polyester film is often used as a base film, and a heat-sensitive transfer layer is made of a mixture of a dye or a pigment and a wax, or a mixture of a sublimable dye and a binder resin, depending on the transfer method. However, due to the demand for higher temperature of the thermal head or thinner base film, the conventional film is insufficient in heat resistance and the like, resulting in problems such as sticking due to improvement of recording speed and print quality. To solve such a problem, for example, Japanese Patent Application Laid-Open No. 61-8628
No. 8 discloses that using an aromatic polyamide film as a base film does not cause a sticking problem without using a back coat layer.

However, aromatic polyamides are excellent in heat resistance and do not cause sticking, but they are required to be used at higher temperatures. Today, the film is softened, causing abrasion and wrinkles in a head, resulting in deterioration of image quality. The problem has been pointed out. Such a problem can be solved by providing a back coat layer, but the number of steps increases, which is not economically preferable. Also, JP-A-63-98484 and JP-A-63-98484
JP-A-237989 discloses that the surface is roughened by incorporating particles into a base material, and the running performance is improved by setting the dynamic friction coefficient or the surface roughness to a specific range. .

Further, from the viewpoint of cost and consideration of the global environment, there has been a trend toward multi-use of the thermal transfer recording medium, and the thermal transfer layer has received several thermal histories. There is a demand for improved adhesion between the substrate and the base film. In particular, a method called the n-fold method is to increase the speed of the image receiving sheet to n times (n> 1) the speed of the transfer sheet and to achieve high density
In addition, printing is performed many times, but at this time, a large stress is applied between the image receiving sheet and the transfer sheet, which causes generation of wrinkles and insufficient adhesion between the transfer layer and the substrate. However, there was a problem that the transfer layer was peeled off.

In recent years, there has been a strong demand for higher-definition thermal transfer recording media, and when gradation expression is expressed by a thermal threshold value, the characteristics of the substrate or the adhesion between the substrate and the thermal transfer layer interface are further increased. In order to maintain heat resistance, heat resistance is required.

However, in the conventional method as described above, the absolute number of the projections is largely insufficient, and it is necessary to add a large amount of particles in order to obtain sufficient adhesion, resulting in poor film forming property and economic efficiency. Be impaired. In addition, since the projection by the means is relatively large, the surface is exposed and the printing accuracy is rather lowered. In addition, in the case of hard particles such as inorganic particles, the head is shaved and the durability of the printer itself deteriorates.

[0008]

DISCLOSURE OF THE INVENTION The present invention solves the above problems, and does not impair the excellent heat resistance and mechanical properties of the aromatic polyamide.
It is an object of the present invention to provide a heat-sensitive transfer recording medium having excellent running properties and printing characteristics in which a transfer layer is not detached even in a high stress state, and wrinkles and deformations do not occur.

[0009]

That is, the present invention relates to a heat-sensitive transfer recording medium having a heat-sensitive transfer layer on one surface of a base film containing aromatic polyamide and / or aromatic polyimide as a main component. At least one surface of the material film has the following two protrusion groups, [1]: 10 fine protrusions having a height of 30 nm or more and a maximum diameter of 5 nm or more from the flat surface of the film.
² to 10 ⁸ protrusions / mm ² , [2]: characterized in that ultra-fine protrusions having a height from the flat surface of the film of less than 30 nm and a maximum diameter of 5 nm or more have 5 × 10 ⁸ protrusions / mm ² or more. The present invention also relates to a thermal transfer recording medium having a thermal transfer layer on one surface of a base film containing aromatic polyamide and / or aromatic polyimide as a main component, At least one surface of the base film has the following two protrusion groups, [1]: a height of 30 from the flat surface of the film.
10 ² to 1 fine projections with a maximum diameter of 5 nm or more
0 ⁸ / mm ^{2, [2]:} height from the film flat surface is 30
5 × 1 ultra-fine projections with a maximum diameter of 3 nm or more, less than 3 nm
0 ⁸ / mm ² or more, a thermal transfer recording medium characterized by having a.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The aromatic polyamide of the present invention is
50 mol% or more, preferably 70 mol% of the repeating unit represented by the following general formula (I) and / or general formula (II)
It is composed of the above.

General formula (I)

Embedded image General formula (II)

Embedded image Here, Ar ₁ , Ar ₂ , and Ar ₃ each include, for example,

Embedded image Etc. can be mentioned, X, Y _{are, -O -, - CH 2 -} , - CO
_{-, - SO 2 -, -} S -, - C (CH 3) 2 -, - C
It is selected from (CF ₃ ) _2- and the like, but is not limited thereto.

Further, hydrogen atoms on these aromatic rings may be halogen groups, nitro groups, C1-C3 alkyl groups, C1-C3
May be substituted with a substituent such as an alkoxy group, a trimethylsilyl group, an aryl group, an oxyaryl group, and a thioaryl group, and hydrogen on the amide group may be substituted with another substituent.

In terms of characteristics, it is preferable that the above aromatic ring bonded at the para position accounts for 50% or more, preferably 70% or more, more preferably 75% or more of the total aromatic ring. If the amount is less than 50 mol%, when formed into a molded product, sufficient functions as a film such as strength, elongation, rigidity and heat resistance cannot be achieved. When such a condition is satisfied, the film can be made thinner, the heat transfer efficiency can be improved, and good printing characteristics can be achieved. Examples of such para-oriented aromatic nuclei include the following.

[0014]

Embedded image Further, the substituent for replacing hydrogen on the aromatic nucleus is preferably used because its solubility and hygroscopicity are improved by its introduction. Particularly in a highly substituted system, it becomes soluble in an organic solvent, and the film-forming properties and surface properties are greatly improved. In order to obtain such an effect, an aromatic polyamide in which a part of hydrogen atoms of the aromatic ring is substituted by a halogen group (particularly chlorine) is preferably 50% or more of the entire aromatic ring, but depending on the use mode, an aromatic polyamide is preferably used. In some cases, a harmful substance is generated due to the decomposition behavior of the thermal head and the thermal head is corroded. In such a case, the same effect can be obtained by the following system, for example.

Group A comprising structural units having different aromatic nuclei represented by the general formula (III),

Embedded image A group B comprising structural units having different aromatic nuclei represented by the general formula (IV), and the general formula (IV)

Embedded image And a group C composed of structural units having different aromatic nuclei represented by the general formula (V), and the general formula (V)

Embedded image (Where Ar ₄ , Ar ₅ , and Ar ₆ are para-oriented aromatic nuclei, and the compounds in each group are halogen groups represented by Ra, Rb, and Rc (provided that the aromatic rings substituted with the substituents are all Less than 15% of aromatic ring), nitro group, cyano group, carbon number 1-4
May be substituted with a functional group selected from an alkyl group having 1 to 3 carbon atoms, an alkoxy group having 1 to 3 carbon atoms, a trialkylsilyl group, an oxyaryl group, and a thioaryl group. here,
k, l, and m are numbers from 0 to 4, respectively. Group A,
Group B is substantially equimolar. ), At least two structural units having different basic aromatic nuclei (defined as the remaining portion excluding a functional group and a substituent) are selected from the same group. ). Further, it contains a structural unit of group D represented by the general formula (VI) as needed.

General formula (VI)

Embedded image (Where Ar ₇ and Ar ₈ are para-oriented aromatic nuclei,
Q ₁ and Q ₂ may be the same or different from each other.
Or -NH- group. Z is a bridge atomic group. Also, Rd,
Re is a cyano group, an alkyl group having 1 to 4 carbon atoms, and 1 carbon atom.
A functional group selected from an alkoxy group, a trialkylsilyl group, an oxyaryl group, and a thioaryl group,
n and p are the numbers of 0-4, respectively. However, at this time,
When Q ₁ and Q ₂ are both —CO—, the groups A and (B, D)
When Q ₁ and Q ₂ are both —NH—, (Group A, Group D) and Group B,
When different from each other, the groups A and B are substantially equimolar. ).

Ar _{4 to} Ar ₈ are aromatic nuclei defined in the same manner as Ar _{1 to} Ar _3, and those having para orientation for at least 50%, preferably 70% of the total aromatic ring for the same reason as described above.
More preferably, it is more preferably 75% or more.

Z is a bridge atomic group, and -O
_{-, - CH 2 -, -} CO -, - SO 2 -, - S -, - C
(CH ₃ ) _2- , -C (CF ₃ ) _2- , -O-Ar-O
-(Where Ar is an aryl group) selected from divalent flexible atomic groups such as, but not limited to.

The aromatic polyimide of the present invention is one in which a repeating unit represented by the following general formula (VII) and / or (VIII) comprises at least 50 mol%, preferably at least 70 mol%. .

Formula (VII)

Embedded image General formula (VIII)

Embedded image Here, Ar ₉ and Ar ₁₁ include at least one aromatic ring, and two carbonyl groups forming an imide ring are bonded to adjacent carbon atoms on the aromatic ring. This Ar ₉ is derived from an aromatic tetracarboxylic acid or its anhydride.
The following are typical examples.

[0021]

Embedded image Here, Z ′ is —O—, —CH ₂ —, —CO—, —SO ₂
-, - S -, - C (CH 3) 2 - is chosen from such, but is not limited thereto.

Ar ₁₁ is derived from carboxylic anhydride or its halide. Ar ₁₀ and Ar ₁₂ are, for example,

Embedded image And the like, X ', Y' is _{-O -, - CH 2 -,} -
_{CO -, - SO 2 -,} - S -, - C (CH 3) 2 - is chosen from such, but is not limited thereto. Further, some of the hydrogen atoms on these aromatic rings may be substituted with a substituent such as a halogen group (especially chlorine), a nitro group, an alkyl group having 1 to 4 carbon atoms (especially a methyl group), or an alkoxy group having 1 to 3 carbon atoms. And those in which the hydrogen in the amide bond constituting the polymer is substituted by another substituent.

The intrinsic viscosity of the polymer (measured at 30 ° C. as a 100 ml solution of 0.5 g of polymer in sulfuric acid) is
It is preferably 0.5 or more.

As the polymer constituting the base film, an aromatic polyamide is preferable because it is easy to obtain a high Young's modulus and the surface can be formed relatively easily as described later.

At least one surface of the base film used in the present invention has the following two protrusion groups: [1]: fine protrusions having a height of 30 nm or more and a maximum diameter of 5 nm or more from the flat surface of the film are 10 ^2. -10 ⁸ pieces / mm ² , [2]: height 3
Ultrafine projections having a diameter of less than 0 nm and a maximum diameter of 3 to 5 nm or more have 5 × 10 ⁸ protrusions / mm ² or more.

First, the projection group [1] is mainly effective in improving running properties and printing characteristics. In other words, the presence of the protrusion group of [1] improves the contact between the thermal transfer recording medium and the thermal head or the recording paper, and causes sticking, oles, wrinkles, head dents, etc. of the thermal transfer recording medium itself. In addition, bleeding and color shift due to friction with the recording paper can be prevented. In addition, the gap between the head and the head is made appropriate to achieve good heat transfer, and good printing accuracy can be obtained. The projection has a height of 30n from the flat surface of the film.
m or more, preferably 30 nm or more and 1500 nm or less. A projection having a height of less than 30 nm cannot sufficiently obtain the above-described effects. In addition, height 150
A film having a thickness of 0 nm or more is effective for improving running properties, but does not greatly contribute to printing characteristics. The maximum diameter of the projection is 5 nm or more. Preferably 10 nm or more and 2000 nm or less, more preferably 20 nm or more and 150 nm or less.
0 nm or less. Since the projections of less than 5 nm are steep, the effects of the present invention cannot be sufficiently obtained. Also, there is not much noticeable effect even if it is larger than necessary,
The smaller the distance between the projections, the better.
Next, regarding the density, the density of the projections is 10 ² / mm ² or more, preferably 10 ³ / mm ² or more.
0 ⁸ / mm ² or less, preferably 10 ⁷ / mm ² or less. When the amount is less than this range, the effect of improving running properties and printing characteristics is small, and when the amount is large, the surface is rough and the printing characteristics are inferior.

Next, the projection group [2] mainly contributes to the improvement of adhesion and printing characteristics. In other words, the presence of a large number of such ultra-fine projections allows the projections of the above [1] to be formed on the substrate surface by substantially enlarging the surface area without affecting the function in the semi-micro dimension or by the anchor effect thereof. This significantly improves the adhesion to the structure of the heat-sensitive transfer layer and the like. Further, contact with the head is maintained at a very large number of points, a favorable heat transfer environment is achieved, and improvement in printing characteristics can be expected. The height of the projection is less than 30 nm, preferably 10 nm or less, more preferably 0.01 nm or less.
nm or more and 10 nm or less, particularly preferably 0.05 nm or more and 5 nm or less. The maximum diameter of the protrusion is 3 nm or more, particularly preferably 5 nm or more. Although there is no particular upper limit, it is preferably 100 nm or less, more preferably 50 nm.
m or less. If the projection is less than 3 nm, the durability of the projection is inferior and the effect cannot be sufficiently obtained. The density is at least 5 × 10 ⁸ / mm ² , preferably at least 10 ⁹ / mm ^2, more preferably at least 10 ¹⁰ / mm ² . Here, it is extremely preferable that a large number of appropriately low projections exist. If the projections are higher than the above range, unfavorable characteristics relating to the projection density of the projections [1] are caused. If the projection density is less than the above range, it is difficult to obtain sufficient adhesion. There is no particular upper limit, but if it is too large, no remarkable effect is observed. The projections [2] are preferably provided on the thermal transfer layer side or on both front and back surfaces.

The aromatic polyamide and / or aromatic polyamide film used in the present invention may be blended with particles, lubricants, antioxidants and other additives to such an extent that the physical properties of the base film are not impaired. .

Here, in the base film used in the present invention, the projections [1] are formed by the added particles.
It is preferable that the projections of the above [2] are formed substantially without depending on particles. The term “substantially” as used herein means 90% or more, preferably 99% or more, and more preferably 99.9% or more of the target projection. As described above, since the protrusion of the above [1] has an effect on running properties, a strong effect can be expected if the protrusion is reinforced by particles. Conversely, if there are no particles, sufficient action cannot be expected due to deformation or shaving. In addition, if many of the projections of [2] are made of added particles, the surface of the entire base film becomes hard, and the facing structure of the head, recording paper, etc. is shaved, and printing characteristics,
The life of the head may be adversely affected. In order to form the projections not depending on the particles, for example, as described in the production of the base film of the present invention described below, microvoids or polymer concentration unevenness are formed near the surface, and then stretching and stretching are performed.
A method of forming the surface into a shape in a drying step or the like can be used. At this time, irregularities are formed on the film surface,
The projections in [2] are for counting relatively convex portions.

The tensile Young's modulus of at least one direction of the substrate film used in the present invention (20 ° C., relative humidity 60
%) E20 is E20 ≧ 6.9 GPa, preferably E20 ≧ 7.
8 GPa, more preferably E20 ≧ 8.8 GPa. If the Young's modulus is less than 6.9 GPa, it means that deformation tends to occur under tension, which causes wrinkles and breaks, which greatly impairs printing characteristics. Also, E20 ≧
At 6.9 GPa, the film can be made thinner, so that heat transfer efficiency is good and clear printing is possible.

The elongation of the substrate film used in the present invention is preferably 10% or more, more preferably 20% or more.
Particularly preferably, when the content is 30% or more, a flexible and easy-to-handle thermal transfer recording medium can be obtained.

The moisture absorption of the substrate film used in the present invention is 2.5% or less, preferably 2.0% or less, more preferably 1.7% or less. If it exceeds 2.5%, bubbles may be generated in the film when heated, and printing properties may be impaired. This moisture absorption can be achieved by introducing a substituent into the molecular structure. In the case of the aromatic polyamide of the present invention, it is preferable to treat the terminal with aniline, phthalic anhydride, benzoyl chloride or the like, since the moisture absorption can be further reduced.

The dimensional change of the aromatic polyamide and / or aromatic polyimide film of the present invention at 200 ° C. under a tension per 1 kg / mm ² cross-sectional area is preferably 2% or less, more preferably 1% or less. . Films exceeding 2% cause dimensional fluctuations during printing, causing wrinkles and scratches and deteriorating printing characteristics. The dimensional change rate is obtained by fixing one end of a film having a predetermined length, attaching a weight having a predetermined weight to the other end so that the load is evenly applied, performing a heat treatment, and calculating a dimensional change rate before and after the processing. The dimensional change rate can be heat-treated in the range from the glass transition temperature to several tens of degrees Celsius after film formation and stretching,
The range can be set to a preferable range by means such as performing a relaxation process.

Next, a method for obtaining the thermal transfer recording medium of the present invention will be described. Of course, the present invention is not limited to the following description.

The method for obtaining the aromatic polyamide includes, for example, a low-temperature solution polymerization method, an interfacial polymerization method, a melt polymerization method, and a solid-phase polymerization method. In the case where the aromatic polyamide is obtained from diacid chloride and diamine, for example. , N-methylpyrrolidone (NMP), dimethylacetamide (DMAc), and dimethylformamide (DMF). When acid chloride and diamine are used as monomers in a polymer solution, hydrogen chloride is by-produced.When neutralizing this, an inorganic neutralizing agent such as calcium hydroxide, calcium carbonate, lithium carbonate, or ethylene is used. Oxide, propylene oxide, ammonia,
Organic neutralizers such as triethylamine, triethanolamine, diethanolamine, etc. are used. The reaction between the isocyanate and the carboxylic acid is performed in an aprotic organic polar solvent in the presence of a catalyst.

These polymer solutions may be used as they are as a stock solution for obtaining a molded article, or a polymer solution may be isolated once and then redissolved in the above organic solvent or an inorganic solvent such as sulfuric acid to prepare a stock solution. May be.

At the time of this polymerization, it is a matter of course to use a high-purity raw material and a solvent from which impurities such as water have been removed. It is extremely important to provide shear stress and mix efficiently. The reaction for forming an aromatic polyamide is accompanied by a very exothermic reaction at the beginning of the reaction. The reaction heat causes a reaction with the solvent molecule and deactivation of the active terminal, thereby generating an oligomer molecule. Therefore, it is preferable to control the mixing speed to decrease from the beginning to the end of the polymerization in accordance with the increase in the viscosity of the solution. Said means can also sharply control the molecular weight distribution of the polymer and have a favorable effect on mechanical properties and moisture absorption.

In the stock solution for obtaining the aromatic polyamide used in the present invention, an inorganic salt such as calcium chloride, magnesium chloride, lithium chloride, lithium nitrate or the like is added as a dissolution aid in a range not to impair the object of the present invention. Is also good. Further, the polymerization stock solution may be used as it is, but may be used after reprecipitation with water or the like and then dissolving in a solvent. The polymer concentration in the stock solution is preferably from 2 to 40% by weight, more preferably from 5 to 35% by weight. Below this range, it is necessary to take a large amount of ejection, which is economically disadvantageous. If it exceeds this range, it is difficult to obtain a thin film due to the relationship between the amount of ejection and the viscosity of the solution.

On the other hand, a solution of an aromatic polyimide or polyamic acid is prepared by dissolving tetracarboxylic acid in an aprotic organic polar solvent such as N-methylpyrrolidone (NMP), dimethylacetamide (DMAc) or dimethylformamide (DMF) as polyamic acid. It can be obtained by a method such as reacting an acid dianhydride or a tricarboxylic anhydride chloride with an aromatic diamine. The aromatic polyimide can be prepared by heating a solution containing the above-mentioned polyamic acid or adding an imidizing agent such as pyridine to form a polyimide, and after reprecipitation, dissolving in a solvent.

Next, SiO ₂ , TiO ₂ , TiN, Al
_The content of particles such as inorganic particles and organic particles such as ₂ O ₃ , ZrO ₂ , zeolite and other fine metal powders is 0.01 to 20% by weight per polymer weight, preferably 1 to 15%.
% By weight. It is preferable that these particles contain a colored component, since leakage of information from the film after printing can be prevented.

The method of adding the particles is not particularly limited, but if it is necessary to adjust the degree of dispersion and the degree of aggregation of the particles, it is preferably adjusted using a stirring disperser, a ball mill, an ultrasonic disperser or the like.

The dispersed particles are mixed with the polymer solution, and may be added to a solvent before polymerization, added after polymerization, or added at the time of preparing the polymer solution, or may be added immediately before discharge.

Next, the film formation will be described. The film forming stock solution prepared as described above is formed into a film by a so-called solution film forming method. The solution casting method is a dry-wet method,
Although there are a dry method and a wet method, in the present invention, it is appropriate to apply a dry-wet method or a wet method. Here, the dry-wet method will be described as an example.

When a film is formed by a dry-wet method, the stock solution is extruded from a die onto a support such as a drum or an endless belt to form a thin film, and then the solvent is scattered from the thin film layer to dry until the thin film has a self-holding property. I do. Drying conditions are, for example,
The reaction can be performed at room temperature to 220 ° C. for 60 minutes or less. At this time, it is preferable that the residual amount of the solvent as a film after drying is large, and it is preferable that the amount is 45% or more. In addition, it is necessary to heat gently so that a skin layer or a dense layer (a layer having an extremely low solvent content) is not formed on the surface. At this time, an internal heating method such as infrared or electromagnetic heating, a method of preheating the support in advance, or a method of heating from the support side after casting is very effective in obtaining the present invention. The film after the dry process is peeled from the support, introduced into a wet process, subjected to desalination, solvent removal, and the like, and further subjected to stretching, drying, and heat treatment to form a film. In this step, wet process, stretching,
The heat treatment process plays an important role.

In this step, a poor solvent such as water is usually used to remove the solvent. However, when the film surface of the present invention cannot be obtained (usually, the projections of the above [2] are rough), a poor solvent and a good solvent are mixed. Use a medium. In the wet process, the film formation speed is generally slow, so that the solvent is rich in the polymer solution near the film with the progress of the desolvation. Increasing speed,
It is extremely effective that the coagulating medium in the coagulating bath is brought into contact with the film at a flow rate. The bath temperature can be arbitrarily selected, but a lower bath temperature is preferable because the height of the projections in the above [2] can be kept low. However, if the temperature is too low, the productivity is affected. For example, when the polymer stock solution is an organic solvent system, the purpose can be more easily achieved by setting the temperature at about 40 ° C. as a guide. In addition, when the film is shrunk during the wet process and the film is stretched, the formation of the protrusion [2] can be effectively performed.

The stretching can be performed during the wet process or at the time of heating, but the stretching ratio is 1.1 to 8.0 (area ratio is defined as a value obtained by dividing the area of the film after stretching by the area of the film before stretching). )) Is usually used, but it is easier to form a structure having a crosslinked structure and a cured structure on the surface by physical means such as electron beam or chemical means such as a crosslinking reaction before stretching. The substrate film surface of the present invention can be obtained.

The heat treatment is performed at 150 ° C. to 500 ° C.
C. is usually used. In the present invention, the heat treatment is preferably carried out at a temperature of from the glass transition temperature (Tg) to Tg + 50 ° C. of the polymer for a few seconds to a few minutes or with a slight relaxation. Furthermore, slow cooling of the film after stretching or heat treatment is effective in suppressing dimensional fluctuation, and cooling at a rate of 50 ° C./sec or less is effective.

The aromatic polyamide and / or aromatic polyimide film used in the present invention has excellent mechanical properties, so that when it is made into a thin film, it exhibits an excellent effect not found in other materials. The preferred thickness is 0.
It is 5 to 50 μm, more preferably 1 to 20 μm, and still more preferably 2 to 10 μm.

The substrate film used in the present invention may be a single-layer film or a laminated film. Each component when forming a laminated film may be the same or different. For example, in the case of two layers, the polymerized polymer solution is divided into two parts, different particles are added, and then the layers are laminated. The same applies to the case of three or more layers. These laminating methods include well-known methods such as lamination in a die, lamination in a composite tube, and a method in which one layer is formed once and another layer is formed thereon.

The content of the oligomer having a molecular weight of 1,000 or less in the base film used in the present invention is preferably less than 1% by weight, more preferably less than 0.5% by weight. The oligomer referred to herein includes at least a part of the aromatic polyamide structural unit of the present invention, and includes, for example, a reaction product with a solvent. If the content of the oligomer exceeds 1% by weight, the mechanical and thermal properties of the film may be impaired, or the film may be wrapped around by rollers or the like during use, or the heat-sensitive transfer recording layer may peel off. is there.

Further, metal ions (especially ions of IA group and IIA group of the periodic table) in the base film used in the present invention.
Is preferably 3000 ppm or less, more preferably 10 ppm or less.
If it is 0 ppm or less, particularly preferably 30 ppm or less, it is possible to obtain an excellent heat-sensitive transfer recording medium having no influence of corrosion of the thermal head. The metal ion referred to here is an ionized metal component, and excludes a metal component constituting a solid that can be separated from a solution by filtration or centrifugation, such as external particles.

This not only increases the purity of the raw materials including the solvent, but also prevents the formation of a dense layer on the surface in the step of extracting the film-forming solvent and the inorganic salt during film formation. It is necessary to take care to prevent a skin layer or the like from being formed during drying as described above. Also, the wet bath can be preferably adjusted by using a plurality of baths and providing a temperature gradient or a concentration gradient.

Next, in order to obtain a thermal transfer recording medium, a thermal transfer recording layer is formed on the base film obtained by the above method. Before forming the recording layer, the surface of the base film may be subjected to glow treatment or corona treatment. The method of forming the heat-sensitive transfer recording layer includes hot melt coating on the surface of the film, or dissolving in a solvent to obtain gravure, reverse,
It can be performed by a known method such as performing a general-purpose coating such as a slit die coater, and the layer is a melt transfer type including a mixture of a dye or a pigment and a melt type binder such as wax, a sublimable dye and a binder resin. Sublimation type, monochromatic, or color system composed of a mixture of the above and a known multi-use process may be performed. However, since the present invention is excellent in adhesiveness when heated, the sublimation type thermal transfer recording It is preferable that the width is 100 mm or more, preferably 150 mm or more, more preferably 220 mm or more, because it is suitable for materials and is suitable for line head type printers.

Although the present invention is particularly suitable for recording using a thermal head, it is possible to use a means other than the thermal head, for example, a means such as a thermal printing plate, a laser beam, or heat generation in a substrate film. It can also be used for recording.

[0055]

EXAMPLES The method for measuring physical properties and the method for evaluating effects according to the present invention are as follows.

(1) Projection density, projection height Hitachi Field Emission Scanning Electron Microscope (S80
The substrate surface was observed at a magnification of 30,000 times or 50,000 times or more using Type 0), and the diameter was 3 nm or more (the number of projections at this time is N1) and the diameter was 5 nm or more (the number of projections at this time was N1). N2) were counted. here,
The projection diameter was determined based on the diameter of the bright spot when observing from the upper surface, if the projection was present, the image would be contrasted by the inclined surface. If the projections are so small that observation is difficult, the sample surface may be inclined by about 45 degrees.

The observation conditions are as follows.

Acceleration voltage: 10 kv. Sample preparation: Pt sputter coating.

B. Surface observation was performed using an atomic force microscope (Nanoscope IIIa) manufactured by Digital Instruments. In addition, the number of protrusions when the diameter of the protrusions was 3 nm or more and 5 nm or more were cut along the threshold surface (30 nm) from the flat surface was determined.
3, the number of protrusions when the diameter is 5 nm or more is N4).

The observation conditions are as follows.

Scan size: 20 μm, scan speed: 0.5
Hz At this time, the projection density at each height can be obtained by cutting at an arbitrary threshold plane.

When the number of protrusions is obtained by the methods A and B,
The projection density of the above [1] is N4, and the projection density of the above [2] is (N1
-N3) or (N2-N4) (however,
When N1 >> N3 or N2 >> N4, the projection density of [2] above was N1 or N2, respectively. ).

Whether or not each projection is formed by particles is determined by, for example, obtaining an element distribution by focusing on elements caused by particles on the observation surface with an electron microscope equipped with an electron beam microanalyzer or the like. In microscopic observation such as AFM, the protrusion can be confirmed or sampled or marked with a probe and analyzed by elemental analysis.

(2) Moisture Absorption A few grams of the base film is dried in a vacuum drier at 100 Pa or less and at 180 ° C. until a constant weight is reached, and its weight is defined as W1. Then, the film was heated at 25 ° C., 75%
After placing in the environment of RH for 48 hours, the measured weight is
Let it be 2. The moisture absorption was determined as (W2−W1) / W1 × 100 (unit:%).

(3) Young's modulus, elongation Using Orientec Tensilon, test length 50 mm,
The test was performed at a tensile speed of 300 mm / min.

(4) Weight fraction of oligomer The film was dissolved in a solvent, and a low-angle laser light scattering photometer (LALL) was applied to a gel permeation chromatograph (GPC).
S) and a differential refractometer (RI) are incorporated, and the molecular weight and the content of the solute are sequentially determined by measuring the light scattering intensity and the refractive index difference of the molecular chain solution size-separated by a GPC device according to the elution time. After calculating, the absolute molecular weight distribution of the high molecular weight substance was finally calculated. Diphenylmethane was used for calibration of the absolute molecular weight.

As a simple method, it is also possible to simply obtain a fraction having a molecular weight of 1,000 or less from a solution that has been subjected to size separation and remove the solvent.

(5) Metal ion content The base film is dissolved in a solvent, and particles and the like are removed by a centrifuge or filtration. Next, components other than the particles were recovered from the solution, quantified, burned, incinerated, dissolved in nitric acid and hydrofluoric acid, and then solubilized with dilute nitric acid.

Next, quantification was performed using an atomic absorption spectrometer based on a calibration curve prepared in advance. Here, the unit ppm is (μg / g).

(6) Printing Characteristics Coatings consisting of four kinds of sublimable dye-binder mixtures of yellow, cyan, magenta and black were applied to the substrate film and dried to form four-color heat-sensitive transfer recording layers. The thickness of the transfer layer after drying is 3 μm.

Dye 10 parts by weight Particle-containing polyvinyl butyral resin 20 parts by weight Toluene 90 parts by weight Methyl ethyl ketone 90 parts by weight Using this sheet, a printing machine equipped with an A4 size edge type line head was applied with a power of 20 W / mm ² , a pulse width of 4 ms, Full-color printing was performed at a pressure of 110 g / cm, and the printing characteristics were determined based on the following criteria.

A: extremely excellent ：: Excellent. ●: Somewhat excellent. Δ: Slightly inferior. ×: Bad.

Examples 1 to 5, Comparative Examples 1 to 3 Abbreviations of the respective raw materials used in the following Examples and Comparative Examples are as follows.

Aromatic diamine component: CPA: 2-chloroparaphenylenediamine DPX: 2,5-dimethylparaphenylenediamine MPA: metaphenylenediamine DMB: 3,3′-dimethylbenzidine DPE: 4,4′-diaminodiphenylether acid Chloride component: TPC: terephthalic dichloride CPC: 2-chloroterephthalic dichloride IPC: isophthalic chloride Anhydride component: BTA: 3,3 ', 4,4'-biphenyltetracarboxylic anhydride

Example 1 Dehydrated N in a reactor having a cooling jacket with a diameter of 1.8 m was provided.
-80 mol% in methylpyrrolidone (hereinafter abbreviated as NMP)
Of CPA, 20 mol% of DPE are dissolved and the solution is cooled. Then, 100 mol% of CPC was added and the peripheral speed was increased to 4%.
After stirring for 2 hours while changing from m / sec to 2 m / sec, the mixture was neutralized with lithium hydroxide to obtain a polymer.

An NMP slurry in which silica particles having an average primary particle diameter of 16 nm were previously dispersed was added to this solution at 2% by weight of the particles of the polymer. After defoaming, the solution was passed through a 5 μm-cut filter and passed over a 70 ° C. stainless belt. Extend, 170
After evaporating the solvent content at 56 ° C to 56%, the self-supporting film was peeled off from the belt and kept at 40 ° C as first, second and third circulating water tanks each containing 2 NMP / water.
The mixture was passed through a water tank having a composition ratio of 0/80, 10/90, 0/100. At this time, the film was stretched 1.1 times in the longitudinal direction after the second water tank. Then, it is dried and heat-treated at 300 ° C. in a tenter, stretched 1.2 times in the width direction at this time, further heat-treated for 1 minute while keeping the fixed length, and then cooled to room temperature at a rate of 20 ° C./sec to obtain a thick film. A film having a thickness of 6 μm was obtained. The height from the flat surface of this film is 30 nm or more, and the maximum diameter is 5 n.
1 × 10 ⁶ fine protrusions of m or more (hereinafter abbreviated as protrusion [1])
1 × 10 ⁹ ultra-fine protrusions (hereinafter, abbreviated as protrusion [2]) having a number of pieces / mm ² , a height of less than 30 nm, and a maximum diameter of 3 nm or more.
１1 × 10 ¹⁰ pieces / mm ² . At this time, the diameter of the projections [2] was almost all 5 nm or more, and the height was almost less than 10 nm (that is, in the frequency distribution of the projection heights, the diameter of the projections was less than 10 nm). Hyperfine protrusions in the range appear as two peaks.) Further, as a result of the analysis, it was found that the protrusion [1] was formed by the particles, but at least 99% of the protrusion [2] was formed by the particles.

The moisture absorption of this film is 1.5%,
Elongation and Young's modulus in the longitudinal direction are 45% and 11.2, respectively.
7 GPa, the dimensional change was 0.1%, the metal ion content was 25 ppm, and the oligomer content was less than 0.5%.

The thermal transfer recording medium using this film exhibited extremely good full-color printing characteristics.

Example 2 Polymerization was carried out in the same manner as in Example 1, and an NMP slurry in which titania particles having an average primary particle size of 50 nm were previously dispersed was added to this solution so that the particles became 3.5% by weight per polymer. Then, a film was formed in the same manner as in Example 1 except that the stretching ratio in the wet process was set to 1.15, to obtain a film having a thickness of 6 μm.

The number of protrusions [1] of this film was 5 × 10 ⁶ /
mm ² , protrusions [2] are 1 × 10 ⁹ to 1 × 10 ¹⁰ / mm ²
Met. In this case, the diameter of the projections [2] was almost all 5 nm or more, and the height was almost less than 10 nm. Further, as a result of the analysis, it was found that the protrusion [1] was formed by the particles, but at least 99% of the protrusion [2] was formed by the particles.

The moisture absorption of this film is 1.5%,
The elongation and Young's modulus in the longitudinal direction are 45% and 11.7, respectively.
6 GPa, the dimensional change was 0.15%, the metal ion content was 25 ppm, and the oligomer content was less than 0.5%.

The thermal transfer recording medium using this film exhibited good full-color printing characteristics, but seemed to have slightly uneven printing density.

Example 3 A polymer solution polymerized by the method of Example 1 was added to an average primary particle size of 1
An NMP slurry in which silica particles of 6 nm are dispersed in advance is added at 2% by weight per polymer, and as a wet process, water at 20 ° C. is used as a first circulating water tank, and 30 ° C. is used as a second, third, and fourth circulating water tank. NMP / water 35/65, 15
/ 85, 0/100. At this time, the film was stretched 1.2 times in the longitudinal direction after the second water tank. Then, it is dried and heat-treated at 290 ° C. in a tenter, stretched 1.3 times in the width direction, relaxed by about 1%, heat-treated at 300 ° C. for 1 minute, and cooled to room temperature at a rate of 20 ° C./sec. Thus, a film having a thickness of 6 μm was obtained.

The number of protrusions [1] of this film was 1 × 10 ⁶ /
mm ² and the number of protrusions [2] exceeded 1 × 10 ¹⁰ / mm ² . At this time, the diameter of the projections [2] was almost all 5 nm or more, and the height was almost less than 10 nm. Further, as a result of the analysis, it was found that the protrusion [1] was formed by the particles, but at least 99% of the protrusion [2] was formed by the particles.

The moisture absorption of this film is 1.5%,
Elongation and Young's modulus in the longitudinal direction are 44% and 11.2, respectively.
7 GPa, the dimensional change was 0.1%, the metal ion content was 15 ppm, and the oligomer content was less than 0.5%.

The thermal transfer recording medium using this film exhibited extremely good full-color printing characteristics.

Example 4 N dehydrated in a reactor with a cooling jacket having a diameter of 1.8 m was provided.
40 mol% DPX, 40 mol% DMB, 20
Dissolve the mole% DPE and cool the solution. Then 1
A peripheral speed of 4 m / sec to 2 m was added by adding 00 mol% of TPC.
The mixture was stirred for 2 hours while changing to / sec, and neutralized with lithium hydroxide to obtain a polymer.

To this solution was added 0.7% by weight of colloidal silica particles having an average particle diameter of 25 nm per polymer, and the mixture was stirred until it became uniform. After defoaming, the mixture was passed through a 5 μm-cut filter and cast on a stainless steel belt. After evaporation at 180 ° C. until the solvent content became 55%, the film having self-supporting property was peeled off from the belt, and the remaining solvent and the like were extracted in the same manner as in Example 1. At this time, after the second water tank, 1.1 in the longitudinal direction.
It was stretched twice. Then, it is dried at 275 ° C. in a tenter, stretched 1.2 times in the width direction, further relaxed by about 1%, heat-treated at 290 ° C. for 1 minute, and cooled to room temperature at a rate of 20 ° C./sec to a thickness of 6 μm. Was obtained.

The number of protrusions [1] of this film was 1 × 10 ⁵ /
mm ² and the number of protrusions [2] were about 1 × 10 ⁹ / mm ² .
At this time, the diameter of the projection [2] was almost all 5 nm.
As described above, the height was almost less than 10 nm. Further, as a result of the analysis, it was found that the protrusion [1] was formed by the particles, but at least 99% of the protrusion [2] was formed by the particles.

The moisture absorption of this film was 1.8%,
The elongation and Young's modulus in the longitudinal direction are 42% and 10.2, respectively.
9 GPa, the dimensional change was 0.0%, the metal ion content was 30 ppm, and the oligomer content was less than 0.5%.

The thermal transfer recording medium using this film exhibited extremely good full-color printing characteristics.

Example 5 Dehydrated N was placed in a reactor having a cooling jacket with a diameter of 1.8 m and a cooling jacket.
Dissolve 60 mol% of CPA and 40 mol% of DPE in MP and cool the solution. Next, 100 mol% of BTA was added to the mixture, and the peripheral speed was adjusted to 2 m / sec, followed by stirring for 2 hours to obtain a polymer.

An NMP slurry in which silica particles having an average primary particle size of 45 nm were previously dispersed was added to this solution in an amount of 4% by weight of the particles per polymer. After defoaming, the solution was passed through a 5 μm-cut filter and passed over a 70 ° C. stainless belt. Extend, 170
After evaporation at 43 ° C. until the solvent content became 43%, the film having self-supporting properties was peeled off from the belt, and the remaining solvent and the like were extracted as in Example 1. Then, after evaporating the residual moisture in a drier, treated in a pyridine-containing atmosphere at 100 ° C. for about 10 seconds,
Then, in the tenter, in the longitudinal direction and the transverse direction, respectively, 1.1.
The film was stretched twice and 1.2 times. Then, the cyclization was completed in an atmosphere of 340 ° C., and cooled to room temperature at a rate of 20 ° C./sec to obtain a film having a thickness of 10 μm.

The number of protrusions [1] of this film was 1 × 10 ⁷ /
mm ² and the number of protrusions [2] exceeded about 1 × 10 ¹⁰ protrusions / mm ² . At this time, the diameter of the projections [2] was almost all 5 nm or more, and the height was almost less than 10 nm. Further, as a result of the analysis, it was found that the protrusion [1] was formed by the particles, but at least 99% of the protrusion [2] was formed by the particles.

The moisture absorption of the film was 2%, the elongation and the Young's modulus in the longitudinal direction were 40% and 7.35 G, respectively.
Pa, dimensional change is 0.1%, metal ion content is 10
ppm or less, and the oligomer content was 0.5%.

The heat-sensitive transfer recording medium using this film exhibited good full-color printing characteristics. However, if recording was performed a number of times, the separation from the roller was slightly deteriorated, and wrinkles and wrinkles might occur. Was.

Comparative Example 1 Polymerization and film formation were carried out in the same manner as in Example 1 except that no silica particles were added to obtain a film having a thickness of 6 μm.

The protrusion [1] of this film was 1 × 10 ¹ /
mm ² , projections [2] are 1 × 10 ⁹ / mm ² -1
× 10 ¹⁰ pieces / mm ² .

The moisture absorption of this film was 1.5%,
Elongation and Young's modulus in the longitudinal direction are 48% and 11.2, respectively.
7 GPa, the dimensional change was 0.1%, the metal ion content was 25 ppm, and the oligomer content was less than 0.5%.

The thermal transfer recording medium using this film was inferior in runnability, and was wrapped around a roll, and had wrinkles and wrinkles.

Comparative Example 2 The monomers used were 100 mol% of MPA,
A polymer was obtained by the same polymerization recipe as in Example 1 except that mol% of IPC and 50 mol% of TPC were used, and N was prepared by previously dispersing silica particles having an average primary particle diameter of 16 nm in this polymerization solution.
MP slurry was added at 2% by weight of particles per polymer. After defoaming, the solution was cast on a stainless steel belt through a 5 μm-cut filter, and evaporated at 180 ° C. until the solvent content became 43% to obtain self-supporting property. The film was peeled off from the belt and sequentially introduced into a plurality of stationary water tanks maintained at 40 ° C. to extract the remaining solvent and the like. Then 290 in the tenter
1.25 times each in the vertical and horizontal directions under an atmosphere of ° C.
The film was stretched 1.3 times to obtain a film having a thickness of 10 μm.

The number of protrusions [1] of this film was 1 × 10 ⁶ /
mm ² , the number of protrusions [2] was 1 × 10 ⁸ / mm ² or less.

The moisture absorption of this film is 1.5%,
Elongation and Young's modulus in the longitudinal direction are 52% and 5.4G, respectively.
Pa, dimensional change is 2.2%, metal ion content is 25
ppm, oligomer content was less than 0.5%.

Although the thermal transfer recording medium using this film had good running properties, peeling of the transfer layer was partially observed during printing. In addition, shrinkage caused wrinkles, scratches on the printed surface, and poor print quality.

Comparative Example 3 A polymer was obtained according to the same polymerization recipe as in Example 4, and an NMP slurry in which silica particles having an average primary particle diameter of 16 nm were previously dispersed in the polymer solution was added at 2% by weight per polymer. After defoaming, the solution was cast on a stainless steel belt through a filter having a cut of 5 μm, evaporated while blowing hot air at 180 ° C. until the solvent content became 58%, and the film having self-supporting properties was peeled off from the belt. NMP / ℃
Water was introduced into a 35/65 first static water tank and then into a plurality of static water tanks maintained at 30 ° C. to extract residual solvents and the like. At this time, the film was stretched 1.1 times in the longitudinal direction in the second water tank. Then
Next, in a tenter, under a 290 ° C. atmosphere,
The film was double-stretched, heat-treated for 1 minute in an atmosphere at a constant length of 300 ° C., and cooled at 20 ° C./sec to obtain a film having a thickness of 6 μm.

The projections [1] of this film were 8 × 10 ⁵ /
mm ² , the number of protrusions [2] was 1 × 10 ⁸ / mm ² or less.

The moisture absorption of this film was 1.9%,
The elongation and the Young's modulus in the longitudinal direction are 48% and 10.7, respectively.
8 GPa, the dimensional change was 0.1%, the metal ion content was 110 ppm, and the oligomer content was less than 0.5%.

The thermal transfer recording medium using this film had good running properties, but a part of the transfer layer peeled off during printing. In addition, the head was slightly colored in a large number of recordings.

[0109]

[Table 1]

[0110]

The thermal transfer recording medium based on the aromatic polyamide and / or the aromatic polyamide film of the present invention maintains its original excellent mechanical properties and various performances such as heat resistance while maintaining a high temperature, Even under severe use conditions such as high stress, it has no wrinkles or odors, has extremely good running performance, and has no concern about detachment of the heat-sensitive transfer layer even if the temperature rises, It has excellent printing characteristics because of its good touch. In particular, it is suitable in a case where a severe use environment such as color recording, high definition, and multi-use use is required.

Claims (9)

[Claims] 1. A heat-sensitive transfer recording medium having a heat-sensitive transfer layer on one surface of a base film containing aromatic polyamide and / or aromatic polyimide as a main component, wherein at least one surface of the base film has the following Two protrusion groups, [1]: 10 ² to 10 ⁸ fine protrusions / mm ^{2 with} a height of 30 nm or more and a maximum diameter of 5 nm or more from the flat surface of the film, [2]: a height of 3
Ultra-fine protrusions having a maximum diameter of less than 0 nm and a maximum diameter of 5 nm or more are 5 ×
A thermal transfer recording medium having a density of 10 ⁸ / mm ² or more. 2. A heat-sensitive transfer recording medium having a heat-sensitive transfer layer on one surface of a base film containing aromatic polyamide and / or aromatic polyimide as a main component, wherein at least one surface of the base film has the following structure. Two protrusion groups, [1]: 10 ² to 10 ⁸ fine protrusions / mm ^{2 with} a height of 30 nm or more and a maximum diameter of 5 nm or more from the flat surface of the film, [2]: a height of 3
Ultra-fine projections with a maximum diameter of less than 0 nm and a maximum diameter of 3 nm or more are 5 ×
A thermal transfer recording medium having a density of 10 ⁸ / mm ² or more. 3. The projection group of [1] is [1]: the height from the flat surface of the film is 30 nm or more, the maximum diameter is 10 nm or more,
^{3. The} heat-sensitive transfer recording medium according to claim 1, wherein the number of fine protrusions of 0 nm or less is 10 ² to 10 ⁸ / mm ² . 4. The projection group of [2] is [2]: the height is 0.01 nm.
^{2. The} thermal transfer recording medium according to claim 1, wherein the number of ultrafine projections having a diameter of at least 10 nm and a maximum diameter of at least 5 nm is 5 × 10 ⁸ / mm ² or more. 5. The projection group of [2], wherein [2]: the height is 0.01 nm.
3. The thermal transfer recording medium according to claim 2, wherein the number of ultrafine projections having a diameter of at least 10 nm and a maximum diameter of at least 3 nm is 5 × 10 ⁸ / mm ² or more. 4. 6. In the group of projections provided on the base film, the projections [1] are formed by particles contained in the film, and the projections [2] are substantially independent of the added particles. The thermal transfer recording medium according to claim 1, wherein the thermal transfer recording medium is formed. 7. The base film having a Young's modulus in at least one direction of at least 6.9 GPa and a dimensional change of the film under a load of 1 kg / mm ² at 200 ° C. of 2% or less. Item 7. A thermal transfer recording medium according to any one of Items 1 to 6. 8. The method according to claim 1, wherein the metal ion contained in said base film is 3000 ppm or less.
8. The thermal transfer recording medium according to any one of 7. 9. The thermal transfer recording medium according to claim 1, wherein the thermal transfer layer has a width of 100 mm or more and is a sublimation type thermal transfer layer.