JPS63193887A - Production of thermal transfer recording medium - Google Patents

Abstract

PURPOSE:To enable a high-quality printing even on a low-surface smoothness paper to be subjected to transfer and to prevent a blocking phenomenon, by a method wherein, after at least one release layer is applied on a substrate by hot-melt coating, at least one heat softening layer is formed on the release layer by aqueous coating. CONSTITUTION:On a substrate having a heat resistance and being enhanced in dimension stability and surface smoothness, at least one release layer is applied. This release layer is applied by using a hot-melt coating method. After that, on the release layer at least one heat softening layer is formed by aqueous coating. For the aqueous coating of the heat softening layer, a method in which an aqueous emulsion containing a thermoplastic resin, a heat softening substance, and a coloring agent is prepared to be coated is preferably used. The transfer using a thermal transfer recording medium obtained in the above manner results in the interaction between the release layer and the heat softening layer, which enables a high-quality printing even on a low-surface smoothness transfer paper, and a prevention of blocking in the thermal transfer recording medium.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method of manufacturing a thermal transfer recording medium. More specifically, the present invention provides a method for easily producing a thermal transfer recording medium that can form high-quality prints even on rough paper with low paper surface smoothness and is less likely to cause blocking. Prior art] The thermal transfer recording medium method is a thermal transfer recording medium (ink ribbon for thermal transfer) consisting of a support and a layer of a heat-fusible old coloring agent in which a colorant is dispersed in a heat-fusible substance on the support. Using a thermal head, this colorant layer is heated from the support side of the heat-sensitive transfer recording medium overlaid on a transfer medium (generally paper), and the colorant layer corresponding to the heated area is melted and coated. This is a method of transferring onto a transfer medium.

However, the method using a thermal transfer recording medium has the problem that it is difficult to print with sufficient quality on a transfer medium with a low surface smoothness (so-called rough vapor).

This problem is particularly problematic when using paper, the most widely used transfer medium.

In other words, paper with high smoothness is rather special, and ordinary paper has a considerably uneven surface due to entangled fibers. For example, on the surface of rough paper whose back smoothness is on the order of IO seconds, there are many parts where the depth from the top of the convex part to the four deepest protrusions is greater than 10 meters. When thermal transfer is performed on such paper, if the print density is low, part of the print may be missing, resulting in poor print quality.

Therefore, as a solution to this problem, we created a solution between the support and the meltable colorant layer! A method has been adopted in which a layer called a release layer is interposed to facilitate the separation of the heat-melting colorant layer from the support (JP-A-59-224:192, JP-A No. 60-97).
No. 888, No. 60-187593, No. 60-1831
No. 92, No. 60-115488, etc.).

However, such heat-sensitive transfer recording media are manufactured using the so-called hot-melt coating method, in which the forming components of the heat-melting coloring layer are coated on the support in a molten state, or by dispersing or melting the forming components in an organic solvent. It is generally manufactured using the so-called organic solvent method, which involves applying a solution of water. Therefore, the hot-melt colorant layer tends to mix with part of the release layer during coating, resulting in a continuous layer with unclear divisions between the two, and the characteristics of each layer are no longer exhibited.
Print quality on rough paper is not sufficiently improved. Furthermore, when an organic solvent coating method is used, organic solvents may remain, and these residual organic solvents may cause "stickiness" on the surface of the heat-melting colorant layer, and in such cases, Print quality on rough paper deteriorates.

[Purpose of the invention] The present invention has been made based on the above-mentioned 4S circumstances.

In other words, one object of the present invention is to be able to realize high quality printing not only on transfer paper with excellent surface smoothness, but also on transfer paper with low surface smoothness, and without the blocking phenomenon. An object of the present invention is to provide a method for manufacturing a thermal transfer recording medium.

[Means for achieving the above object 1] The configuration of the present invention for achieving the above object is to apply at least one release layer on a support by hot melt coating, and then coat the release layer on the support. This is a method for producing a heat-sensitive transfer recording medium, characterized in that at least one heat-softening layer is formed by aqueous coating.

As a result of the inventor's study on the characteristics of a heat-softening layer for improving rough paper compatibility, the following was found.

Generally, a layer containing a colorant (hereinafter simply referred to as an "ink layer")
) is peeled from the support by heating with a thermal head and transferred to a transfer medium (specifically, rough paper), the adhesion between the ink layer and the transfer medium is ■Releasability of the ink layer from the support ■Cohesive force of the ink layer ■Elongation at break of the ink layer or print quality.

In thermal transfer recording media manufactured by conventional methods, these characteristics of the ink layer tend to be uniquely determined by the material used.

For example, the cohesive force of an ink layer has a correlation with the adhesive force and elongation at break of this layer, and if an attempt is made to suppress the cohesive force to a certain extent, the elongation at break and adhesive force of the ink layer tend to decrease. Therefore, it has been found that it is very difficult to control all the above-mentioned properties of the ink layer within a suitable range by selecting materials in order to obtain good print quality on rough paper.

The present inventors have arrived at the present invention by discovering that the quality of printing on rough paper can be improved by changing the manufacturing method, rather than by the conventional method of selecting materials constituting the ink layer.

! The support used in the method for producing a thermal transfer recording medium of the present invention is as follows:
It is desirable to have heat-resistant strength, high dimensional stability, and high surface smoothness.

The materials include, for example, papers such as plain paper, condenser paper, laminated paper, and foot paper, resin films such as polyethylene, polyethylene terephthalate, polystyrene, polypropylene, and polyimide caps, composites of paper and resin films, and aluminum foil. Metal sheets such as the above are preferably used.

The thickness of the support is usually 60 lm or less in order to obtain good thermal conductivity.1 In the present invention, the thickness is particularly 1.
It is preferable to use one within the range of 5 to ISpm.

Further, in the present invention, the structure of the back surface of the support may be arbitrary, and the support may have a backing layer for the purpose of preventing sticking.

Base rough side 11 At least one release layer is coated on this support. Can two or more release layers be coated on the support?1
In the present invention, it is preferable that the release layer is a single layer.

This release layer usually contains a heat-fusible substance and a thermoplastic resin, and further contains a colorant in some cases, and is a layer in which attributes of the heat-fusible substance are dominant, This layer mainly has the function of providing one adhesive force between the heat-softening layer and the support.

The heat-melting substance used here has a melting point (Yanagimoto MPJ-2
It is preferable that the solid or semi-solid material has a temperature of 40 to +50°C (measured by mold).

Specific examples include plant waxes such as carnauba wax, wood wax, auriculie wax, and nispar wax; animal waxes such as beeswax, insect wax, shellac wax, and spermaceti wax; paraffin wax, microcrystalline wax,
Petroleum waxes such as polyethylene wax, ester wax, and acid wax; Waxes such as garlic wax such as montan wax, osikerite, and ceresin; Higher fatty acids such as valmitic acid, stearic acid, margaric acid, and behenic acid; valmityl alcohol, and stearyl alcohol. , higher alcohols such as behenyl alcohol, marganyl alcohol, myricyl alcohol and eicosanol.

Higher fatty acid esters such as cetyl palmitate, myricyl palmitate, cetyl stearate and myricyl stearate; amides such as acetamide, propionic acid amide, balmitic acid amide, stearic acid amide and amide wax; stearylamine, behenylamine and Examples include higher amines such as palmitylamine, which may be used alone or in combination.

Examples of thermoplastic resins include polyamide resins, polyester resins, polyurethane resins, polyolefin resins, acrylic resins, vinyl chloride resins, cellulose resins, rosin resins, ionomer resins, and petroleum resins. type, natural rubber, styrene-butadiene rubber,
Elastomers such as isoprene rubber and chloroprene rubber, ester gums, rosin derivatives such as rosin maleic resin, rosin phenolic resin and hydrogenated rosin, phenolic resins, terpene resins, cyclopentadiene resins and aromatic hydrocarbon resins, etc. Softening fortune 50~+51
1st T: You can perform 5-molecular 葬 agglomeration etc.

Among these, the most preferable thermoplastic resin is acrylic resin.

Acrylic resins can be obtained, for example, by emulsion polymerization of monobasic carboxylates such as acrylic acid and methacrylic acid or their esters, and at least one type of heptamine that can be copolymerized with them. The carboxylic acid monomers used in this case include (meth)acrylic acid methyl ester, (meth)acrylic acid ethyl ester, (meth)acrylic acid isopropyl ester, (meth)acrylic acid butyl ester, (meth)acrylic acid isobutyl ester. , (meth)acrylic acid amyl ester, (meth)
Acrylic acid hexyl ester, (meth)acrylic acid octyl ester, (meth)acrylic acid-2-ethylhexyl ester, (meth)acrylic acid decyl ester, (meth)acrylic acid dodecyl ester, (meth)acrylic acid hydroxyethyl ester and (meth)acrylic acid hydroxyethyl ester. Meth)acrylic acid hydroxyethyl ester grass is mentioned. Monomers that can be copolymerized include vinyl acetate, vinyl chloride, vinylidene chloride, maleic anhydride, fumaric anhydride, styrene, 2-methylstyrene, chlorostyrene, acrylonitrile, vinyltoluene, N-methylol acrylamide, N-methylol methacrylate. Examples include amide, N-butoxymethylacrylamide, N-butoxymethacrylamide, vinylpyridine, and N-vinylpyrrolidone, and one or more of these may be selected.

Furthermore, diene cobosomer can also be suitably used as the thermoplastic resin. Specifically, butadiene, isoprene,
Diene thread pickers such as isobutylene and chlorobrene
Examples of emulsion polymers include tutadiene-styrene polymers, butadiene-styrene-vinylpyridine polymers, and butadiene-acrylonitrile polymers. There are chlorobrene-styrene polymers, chlorobrene-acrylonitrile polymers, etc.

Further, as a preferable polymer, an ethylene copolymer can be mentioned. For example, ethylene-vinyl acetate copolymer, ethylene-ethyl acrylate copolymer, ethylene-methyl methacrylate copolymer, ethylene-isobutyl acrylate copolymer, ethylene-acrylic acid copolymer, ethylene-vinyl alcohol copolymer. Polymer, ethylene-
These include vinyl chloride copolymers and ethylene-acrylic acid metal salt copolymers.

As the coloring agent, commonly used pigments such as inorganic pigments and amorphous pigments, and dyes can be used.

Examples of the inorganic pigments include titanium dioxide, carbon black, zinc oxide, Prussian blue, cadmium sulfide, iron oxide and chromates of lead, zinc, barium and calcium. Examples of the organic pigments include azo-based, thioindigo-based, anthraquinone-based, anthurone-based, triphenedioxazine-based pigments,
These include vat dye pigments, phthalonanine pigments such as copper phthalocyanine and its derivatives, and quinacridone pigments.

Examples of organic dyes include acid dyes, direct dyes, disperse dyes, oil-soluble dyes, and metal-containing oil-soluble dyes.

Is there no limit to the content of the thermofusible substance in the release layer? tUsually 50% by weight or more (preferably 50 to 50% by weight) of any total weight.
(within a range of 97% by weight).

The peeled fa layer may or may not contain a colorant, or if it is included, it is usually 30% by weight or less based on the weight of the entire layer.

In addition, the release layer may contain polyoxyethylene chain-containing compounds, inorganic or organic fine particles (metal powder, silica gel, etc.)
, oils (linseed oil, mineral oil, etc.) may also be added.

The thickness of the release layer is usually 0.5 to 4 mm, preferably 1.0 to 2.5 mm.

Viscosity of release layer at 100℃, 2 to 100 cpg
Detame Kaiyu r or Su upper r Kuin 4) Yama to Δ1 Su, 廿to 1 do 1
It would be better to adjust the type of countermeasure etc.

This 'AS layer is coated using a hot melt coating method.

The hot melt coating method is a method in which the components constituting this layer are mixed and the resulting mixture is melted and coated. In this case, the heating humidity is sufficient as long as the heat-melting substance, which is the main component forming this layer, is brought into a molten state.
The melted component can be applied by a known method such as a coating method using a wire bar.

In the above-mentioned hot-melt coating, for example, up to about 20% by weight of an organic solvent can be added to the components used for the purpose of adjusting viscosity.

In the method for producing a heat-sensitive transfer recording medium of Nahi's IJJ, next, at least one heat-softening layer is formed on the above-mentioned release layer by aqueous coating.

This heat-softening layer is a layer whose main components are a thermoplastic resin and a heat-softening substance, and further contains a coloring agent if necessary. This layer is dominated by the attributes of the plastic resin. Therefore, the blending ratio of the thermoplastic resin and the thermosoftening material in the thermosoftening material can be appropriately set within a range that maintains this attribute, or whether this layer or the colorant can be properly applied to the transfer medium. In order to fix the layer to
97% by weight).

As the heat-melting substance, thermoplastic resin, and coloring agent used here, those used in the above-mentioned '' and A delamination can be used.

In this heat-softening layer, the coloring agent is added in an amount of 5 to 35% based on the total weight of the heat-melting substance and the heat-softening substance in this layer.
It is preferable that the content is within the range of weight % weight %.

For water-based coating of this heat-softening layer, an aqueous emulsion containing a thermoplastic resin, a heat-softening substance, and a colorant is prepared;
It is preferable to adopt a method of applying this.

This aqueous emulsion can be prepared, for example, by mixing aqueous emulsions obtained by individually emulsifying the above-mentioned hot-melt substance, thermoplastic resin, coloring agent, and the like.

Here, the aqueous emulsion of the heat-melting substance, thermoplastic resin, and colorant is a system containing an emulsifier, and is emulsified in water by an existing method such as a phase inversion method, a high-pressure emulsification method, or an a-ff wave dispersion method. It can be prepared by As the emulsifier, any of nonionic emulsifiers, anionic emulsifiers, cationic emulsifiers, and amphoteric emulsifiers can be used.

This aqueous emulsion may contain a fluorosurfactant in addition to the emulsifier. The fluorine-based surfactant can effectively prevent the blocking phenomenon of the heat-softening layer, and also has the effect of improving the affinity of the aqueous emulsion for the release layer and effectively preventing so-called "repelling" during coating.

As the fluorine-based surfactant, the following formulas [I] to [VI]
It is preferable to use a compound represented by

Formula [1] CnF2n, SO, M In the above formulas [I] to [VI], M represents an alkali metal or an ammonium group, and R' represents a hydrogen atom or an alkyl group having 1 to 20 carbon atoms. . R2 and R3 each represent an alkyl group having 1 to 20 carbon atoms, which may be the same or different; 2 represents a divalent linking group and represents an alkyleneone residue; n is an alkyl group having 3 to 20 carbon atoms; An integer, m represents an integer from 2 to 20.

Preferred among these are formulas [II, [11], [[]
and [V], and particularly preferred are compounds represented by formulas [II and [m].

One representative compound of the fluorosurfactant used in the present invention is illustrated below.

I-1(:,F,,30:l I-2CaFrtSOxNa I-3C, FrySO, Li I-4CaF, 5O3Nll.

I-5C,F,, So: I 6 CaFrJOJl (4 n-+ ct%F,, 302N (C112CI12
Q),,11n-2(:,F,,502N(C1I□C
II□O),, 11th union II-3C,F,, 302N (C112CII□O),
611■ III I CaF +7SO2NIIC
H□CJO3OJam -2C,F,,5O2NCII
2CII20SOJaI m -3C,F,7SO,N(C112C1I□0)5
SO:lK■ N I CaF +tSOJCl12CIIJP
O (Kano) 2TV-2C, F, 7SO□NC11□0PO
(011)2C121125 IV 3 CnF IV502NC112
C1120PO(011)2C,,11□5 V-1(:aF, 5OJII2C2(:0ONav
-2C,F,,5O2NC112GOOKC,ll.

V-3C,F,7SOJCII□C112GOOKC
,11°Vl ] C7F+5CON11CIlz
C11zCIIJ”1l (C1h)2C1-Vl
2 C9F 19CON11C112C112
C112N◆ (C11U): 1-CI-Vl 3
C7Ft5CONIIC11zCIIzC1l
J"(Clh)3.l-The content of the fluorine-based surfactant in this layer is 0.1% relative to the total solid content of the heat-softening layer.
05 to 3% by weight, especially 0.1 to 2% by weight.
% by weight is preferred. In addition, when having multiple heat-softening layers, it is preferable to increase the content of the upper layer (layer farther from the support) than the content of the lower layer (layer closer to the support). By increasing the content of the agent, blocking resistance tends to improve.

In addition, the aqueous emulsion used in the present invention may contain a thickener such as sodium polyacrylate and a substance that improves surface slipperiness such as colloidal silica in order to adjust the viscosity. Typical examples of water-soluble polymers include polyvinylpyrrolidone, polyvinyl alcohol, water-soluble polyurethane, water-soluble acrylic, water-soluble polyester, and water-soluble polyamide.

At least one layer of the aqueous emulsion thus prepared is coated on the release layer. There are no particular limitations on the coating method, and any known method such as a method using a wire bar or the like can be employed.

The coating thickness of the aqueous emulsion is set to be the dry thickness of this heat-softening layer, which is usually within the range of 0.6 to 5.0 g.m. In particular, it is preferable to apply the coating so that the dry thickness is within the range of 1.0 to 4.04 m.

Furthermore, this heat-softening layer has a viscosity If at 100"C
It is preferable that the f-power is within the range of 400 to 8000 cps, and the type, blending amount, etc. of the heat-melting substance and thermoplastic resin to be used may be determined so as to fall within this range.

In addition, when there are two or more heat-softening layers, it is preferable to apply the outermost heat-softening layer by water-based coating, and in the present invention, in particular, the entire heat-softening layer is coated by water-based coating. It is preferable.

For example, by aqueous coating using an aqueous emulsion, the heat-softening layer is formed with the particles of the components constituting the aqueous emulsion retaining their particle state to some extent. Furthermore, unlike when coating by an organic solvent coating method or a hot melt coating method, the components of the release layer are added to the melting medium during coating.
Since the layer and the detachment layer are not mixed, the two sections form a clear discontinuous layer. Therefore, the characteristics of each layer are not impaired. Moreover, since it does not substantially contain an organic solvent, "stickiness" does not occur on the surface of the heat-softening layer.

-Other matters regarding thermal transfer recording media- Obtained in this way! +! There are no particular limitations on the planar shape of thermal transfer recording media, and they are generally compatible with typewriters.
It is used in the form of a ribbon or a wide tape used in line printers. Further, for color recording, a heat-sensitive transfer recording medium may be provided in which a peeling layer or a heat-softening layer containing colorants of several different tones is coated in stripes or blocks.

The thermal transfer method using the thermal transfer recording medium obtained in the present invention is different from a conventional thermal transfer recording method, and will be explained using the most typical thermal head as an example.

Heat-softening layer of thermal transfer recording medium and transfer medium (%P+l
fs7ri-iM))afy'#美'ni+a'J, 1Fi
1761-, further heat pulses are applied from the back side of the transfer paper by a platen, and a heat pulse is applied by a heat oven to locally heat the release layer and the thermosoftening layer in accordance with the desired printing or transfer pattern. do.

The temperature of the heated portions of the release layer and the heat-softening layer increases, the release layer and the heat-softening layer are quickly softened, and the heat-softening layer is transferred to the transfer medium.

[Effect of the invention] By performing transfer using the heat-sensitive transfer recording medium obtained by the production method of the present invention, at least one release layer coated on the support and a water-based coating applied thereon can be removed. Working together with at least one coated heat-softening layer, it is possible to print with high quality not only on transfer paper with a high surface smoothness, but also on transfer paper with a low surface smoothness. can.

Furthermore, the thermal transfer recording medium obtained by the manufacturing method of the present invention is less likely to cause soloing.

[Examples] Hereinafter, examples of the present invention will be given, but the present invention is not limited thereto. Note that "parts" used below indicate "parts by weight."

(Example 1) The following! A release layer was formed by hot-melt coating the iqa layer coating composition to a film thickness of 1.8 parts m.

``Kawa]'' DK diparaffin wax [melting point 70°C]... 95 parts Ethylene-vinyl acetate copolymer... 5 parts Next, the heat-softening layer coating composition shown below was applied to a wire bar. The film thickness is 2 using
．． A heat-softening layer was formed by aqueous coating on the second part of the release layer so as to obtain a heat-sensitive transfer recording medium of Ogm.

Acrylic water-based emulsion [[Bonneau]-3226J] ・・・・・・・55
8 parts paraffin wax aqueous emulsion Emulsifier made by emulsifying paraffin wax with a melting point of 70°C on wood] 25 parts Carnauba wax aqueous emulsion 10 parts Carbon black aqueous dispersion 25 parts Fluorine surfactant Agent [rFT-248, manufactured by Bayer AG] 0.
5 parts (The expression "~ parts" in the above emulsion is the equivalent weight of the active ingredient in the emulsion.Hereinafter, in the present invention) The obtained thermal transfer recording medium was transferred to a thermal printer A (2 parts).
4 dot serial head, platen pressure 250g/height, platen rubber hardness 70°C), printing speed 40
Rough paper (Spicabond paper) with cps.

The print quality was evaluated by recording (printing) the Bekk smoothness (10 seconds).

Similarly, using thermal printer B (24F printer serial head, platen pressure 400g/head, platen rubber hardness 80°C), record on rough vapor (Lancaster bond paper, Beck smoothness 2 seconds) at a printing speed of 40 cps (
printing) and evaluated the printing quality.

In either case, extremely clear prints (alphabet) without fading, blurring, or background smearing were obtained.Also, for this thermal transfer recording medium, the blocking start temperature at a load of 80 g/cm2 by the temperature gradient method is as follows:
The temperature was 63°C.

(Example 2) A heat-sensitive transfer recording medium was produced in the same manner as in Example 1, except that the following coating set I & was used instead of the heat-softening layer coating composition.

! - 1-゛Ethylene-vinyl acetate aqueous emulsion 50 parts paraffin wax emulsion [emulsion made by emulsifying paraffin wax with a melting point of 70°C in water] 25 parts carbon black aqueous dispersion 25 parts Fluorine surfactant [manufactured by Bayer AG in rFT-248] 0.5
The print quality of the obtained thermal transfer recording media was evaluated in the same manner as in Example 1, and in all cases, clear prints (alphabetic characters) without fading, blurring, or scumming were obtained.

In addition, for this thermal transfer recording medium, the blocking start temperature at a load of 80 g/cm2 according to the temperature gradient method is S0°C.
Met.

(Comparative Example 1) Instead of the coating composition of the heat-softening layer in Example 1,
A heat-sensitive transfer recording medium was prepared in the same manner except that the following heat-softening layer coating composition was heated and dispersed in 300 parts of toluene using a ball mill, and then cooled to coat the prepared coating solution using a wire bar. Manufactured.

H, f Ethylene-vinyl acetate copolymer...50 parts Paraffin wax [melting point 70°C]...25j'll Carbon black...25 parts The print quality of the thermal transfer recording medium was evaluated in the same manner as in Example 1, and in all cases, there were no signs of fading, blurring,
Clear printing (alphabetic characters) could not be obtained due to background smearing.

Further, the blocking start temperature at a load of 80 g/c 2 was determined by the temperature gradient method to be 53°C.

(Comparative Example 2) A thermal transfer recording medium was produced in the same manner as in Comparative Example 1, except that the following coating composition was used instead of the coating composition.

° -ζJ ゛Ethylene-acrylic acid ester copolymer, 50 parts paraffin wax [melting point 70°C]...25 parts carbon black...25 parts carnauba wax... ......The print quality of the 10 copies of the obtained thermal transfer recording medium was evaluated in the same manner as in Example 1. In all cases, only scratches, blurring, and background smudges occurred, and the prints were clear. (Alphabet) could not be obtained.

Moreover, the blocking start temperature at a load of 80 g/cys2 by the temperature gradient method was 54 °C.

Claims (2)

[Claims] (1) A thermal transfer recording characterized in that at least one release layer is coated on a support by hot-melt coating, and then at least one heat-softening layer is formed on the release layer by water-based coating. Media manufacturing method. (2) The method for producing a heat-sensitive transfer recording medium according to claim 1, wherein the heat-softening layer contains a fluorosurfactant.