JPS61162395A - Thermal transfer recording medium - Google Patents

Abstract

PURPOSE:To provide a thermal transfer recording medium capable of being used multiple times while showing high sensitivity even on a transfer paper having a low surface smoothness, by incorporating a polyethylene glycol diester and a wax compound as a heat-fusible substance into a heat-fusible coloring material layer. CONSTITUTION:The polyetheylene glycol diester comprises acid moies at both ends of polyethylene glycol through ester linkage, is preferably one which is solid or pasty at normal temperature (25 deg.C), and particularly preferably has a melting point of 45-80 deg.C from the viewpoints of blocking resistance and sensitivity. A wax compound selected from the group consisting of an animal wax, a vegetable wax, a mineral wax, a petroleum wax, a synthetic hydrocarbon wax and a denatured wax serves also as a binder for the heat-fusible coloring material layer, and a wax which is solid at normal temperature and has a melting point of 40-80 deg.C is used.

Description

[Detailed Description of the Invention] [Industrial Application Field] Related. In detail, the concentration decreases with the number of uses is small,
The present invention relates to a thermal transfer recording medium that can be printed with low energy and provides high density and good print quality.

[Prior Art] As a thermal transfer recording medium intended for multiple uses, for example, Japanese Patent Laid-Open No. 55-105579 describes a technique in which a microporous layer is formed with a resin and the layer is impregnated with ink. Furthermore, JP-A-57-160691 describes a technique for forming a network structure using organic or inorganic fine powder and impregnating it with ink, and JP-A-57-185192 describes , a technique for impregnating porous paper with ink was described, and also published in Japanese Unexamined Patent Publication No. 5
No. 4-68253 discloses that a resin and a solid component immiscible therewith are dissolved and dispersed in a volatile solvent, and after the solvent evaporates,
Techniques are described for forming microporous layers of resin components on supports.

[Problems to be Solved by the Invention] All of these techniques are designed to allow ink to seep out little by little from a porous solid base material. However, since the solid base material does not melt or mix with heat-fusible substances when energy is applied, and is not substantially transferred, the presence of the solid base material in the coloring material layer may cause the coloring material layer to become unnecessarily thick. However, as a result, the density of the dye transfer image is low, and in order to obtain a dye transfer image of high density, high energy is required, and furthermore, there is a drawback that deterioration of resolution is induced. The idea of making it possible to use the ribbon multiple times by incorporating such a solid base material was to simply replace the technology used in conventional pressure-sensitive ribbons (see Japanese Patent Publication No. 35-13426) with a heat-sensitive transfer ribbon. However, due to the difference in the transfer principle, it is rather disadvantageous in terms of sensitivity for thermal transfer.

Therefore, as a technique to solve this drawback, Japanese Patent Laid-Open No. 57
In -36698 and 59-96992,
It is known to interpose an adhesive layer in order to adjust the transfer amount of the heat-melting color material layer, but these techniques have the disadvantage that the density of the dye transfer image is low for transfer paper with low surface smoothness. However, there are drawbacks such as a significant decrease in the density of the dye transfer image depending on the number of times.

The present invention enables low-energy printing, has little loss of density with respect to the number of uses, and can obtain high-density dye transfer images many times. The present invention aims to provide a thermal transfer recording medium that has high sensitivity and can be used many times.

[Means for Solving the Problems] As a result of intensive research, the present inventor has discovered that in a heat-sensitive transfer recording medium having a heat-melt color material layer on a support via an adhesive layer, the heat-melt color It has been discovered that the above technical problem can be solved by containing polyethylene glycol diester and at least one heat-melting substance selected from the following compound group (hereinafter referred to as wax compound group) in the material layer, and the present invention reached.

[Wax compound group] animal wax vegetable wax mineral wax petroleum wax Synthetic hydrocarbon wax modified wax The present invention will be explained in more detail below.

In the heat-sensitive transfer recording medium of the present invention, one or more heat-melting coloring material layers are provided on a support via an adhesive layer. When two or more heat-melting coloring material layers are formed, an intermediate layer may be provided between each layer.

In the present invention, the heat-melting coloring material layer contains polyethylene glycol diester.

The polyethylene glycol diester is polyethylene glycol with acid moieties bonded to both ends, and is preferably solid or paste-like at room temperature (25°C), more preferably A8-188/I+LAtin. , /1m↓kJ fi- t-his measured value), and particularly preferably a melting point of 45 to 80°C from the viewpoint of anti-blocking property and sensitivity.

The molecular weight (weight average molecular weight, same hereinafter) of the polyethylene glycol diester used in the present invention varies depending on the composition of the wax and the properties of the compound, but is preferably 400 to 30,000, more preferably aoo-i 5,000, The molecular weight of the ethylene oxide portion in the molecule is preferably 88 or more and 20,000 or less, and particularly preferably 900 or more and 15,000 or less from the viewpoint of blocking resistance and printing characteristics.

In addition, the diester portion improves miscibility with the heat-melting substance, or when carbon black is contained in the heat-melting coloring material layer, compared to the case of monoglycol ester or simple polyethylene glycol ester. It has the effect of not deteriorating its dispersibility, and it can also achieve stable high density and high print quality even when it is transferred multiple times and when paper with low surface smoothness is used as the transfer paper. The diester moiety changes depending on the molecular weight of the ethylene oxide moiety, but is generally represented by the following formula.

R+ -G -0-CCH2-CH2-0)n -C-
R2 In the above formula, R1 and R2 may be the same or different and represent a saturated or unsaturated hydrocarbon group, or a saturated or unsaturated hydrocarbon group-containing group (aromatic), and n is 1 or more. ,
Preferably it is an integer of 2 to 350.

Typical examples of the diester moieties include those derived from adipose tissue, namely palmitic acid, margaric acid, stearic acid, arachidic acid, behenic acid, lignoceric acid,
Examples include those derived from montanic acid, melisic acid, palmitoleic acid, petrosenic acid, oleic acid, erucic acid, ceracoleic acid, di-, tri-, and tetraenoic acids.

In the above formula, preferable examples of R1 and R2 include saturated or unsaturated hydrocarbons derived from fatty acids, and more preferably hydrocarbons having 10 to 50 carbon atoms. Also, although it depends on the molecular weight of the ethylene oxide part, if the number of carbon atoms is too small, stickiness will occur.
The blocking resistance deteriorates, and on the other hand, if the number of carbon atoms is too large, the melting point becomes too high and the sensitivity becomes low, so it is particularly preferable to have 15 to 30 carbon atoms.

In the present invention, the heat-melting coloring material layer contains at least one heat-melting substance selected from the above wax compound group together with a coloring agent and a polyethylene glycol diester. The heat-melting substance selected from the group of wax compounds also serves as a binder for the heat-melting coloring material layer.

The wax compound group used in the present invention includes waxes that are solid at room temperature, preferably waxes with a melting point (measured by Yanagimoto MPJ-2 type) of 40 to 80°C, and specifically the waxes listed below. is used.

Examples of animal waxes include beeswax, insect wax, cera owl, spermaceti wax, wool wax, etc., and examples of vegetable waxes include carnauba wax, tree wax, auriculie wax, esparto wax, candelilla wax, etc. Mineral waxes include montan wax, osikelite, ceresin, etc. Petroleum waxes include paraffin wax, microcrystalline wax, ester wax, petrolatum, etc. Synthetic hydrocarbon waxes include Fischer-Tropsch, etc. wax, polyethylene wax, low molecular weight polypropylene,
Examples of the modified wax include low molecular weight polyethylene and derivatives thereof, and examples of the modified wax include oxidized wax, montan wax derivative, halafine or microwax derivative. These may be used alone or in combination of two or more, and in the present invention, hydrogenated waxes, such as castor wax and opal wax, which do not belong to the above wax compound group, may also be used in combination. can.

In the present invention, the polyethylene glycol diester contained in the heat-melting coloring material layer may be miscible or immiscible with the wax compound group as a binder. It's okay.

When the polyethylene glycol diester is miscible with the wax compound group, it can be used after being dissolved and mixed. Further, when the polyethylene glycol diester is immiscible with the wax compound group, it can be used after being dispersed, for example, by vigorous stirring.

Furthermore, it is also possible to obtain a finely dispersed state by using a solvent to bring the components into a compatible state during coating and then allowing them to precipitate. To make such a diversification, disilver.

An agitator such as a mixer or a dispersing machine such as a sand mill, ball mill, or roll mill can be used.

The particle size of the dispersion obtained by the above dispersion can be varied depending on the dispersion method and prescription, and in the present invention it is preferably 10 μm or less.

may be contained. In the present invention, the polyethylene glycol diester may be dispersed simultaneously with the colorant or may be dispersed separately. When dispersed separately, the colorant may be dispersed before or after the polyethylene glycol diester of the present invention is dispersed.

The coloring agent used in the heat-melting coloring material layer of the present invention may be appropriately selected from various pigments, preferably direct dyes,
Examples include acid dyes, basic dyes, disperse dyes, oil-soluble dyes (including metal-containing oil-soluble dyes), and dyes such as indoaniline dyes and azomethine dyes can also be preferably used. The pigment used in the color material layer of the present invention is as follows:
In addition to the above, pigments may be used as long as they can be transferred (transferred) together with the heat-melting substance.

Specifically, the following can be mentioned. That is, as the yellow pigment, Kayalon Polyester Light Yellow 5G-3
(Nippon Kayaku), Oil Yellow S-7 (white clay), Isenspiron Yellow GRH Special (Hodogaya), Sumiplast Yellow (Hodogaya) 1, etc. are preferably used.

As a red pigment, Diaceritone Fast Red R (
Mitsubishi Kasei), Dianex Brilliant Red BS-
E (Mitsubishi Kasei), Sumiplast Tread FB (resident), Sumiplast Tread HFG (resident), Kayalon Polyester Pink RCL-E (Nippon Kayaku), Eisenspiron Red GEH Special (Hodogaya), etc. are preferably used. It will be done. Blue pigments include Taiaceridone Fast Brilliant Blue R (Mitsubishi Kasei), Dianix Sprue EB-E (Mitsubishi Kasei), Kayalon Polyester Blue B
-SF Conch (Nippon Kayaku), Sumiplast Blue 3R (
Suitably used are Sumiplast Blue G (Dweller), Sumiplast Blue G (Dweller), and the like. In addition, as a yellow pigment, Hansa Yellow 3G,
Taldrazine Lake, etc. are used, and as a red pigment,
Brilliant Carmine FB-Pure (Sanyo Pigment), Brilliant Carmine 6B (Sanyo Pigment), Alizarin Lake, etc. are used, and as blue pigments, Cerulean Blue, Sumikabrintocyanine Full-〇N-0 (Dweller), Phthalocyanine Blue, etc. are used. The black pigment used is
Of the colorants used in the present invention, carbon black, oil black, etc. are most preferred.

In the present invention, it is particularly preferable that the heat-melting coloring material layer contains a low softening point polymer, and the low softening point polymer is a polymer having a softening point (measured by the ring and ball method) of less than 120°C. are preferred, such as polyethylene, polypropylene, ethylene-ethyl acrylate copolymer, ethylene-
Examples include vinyl acetate copolymers.

Although the composition ratio of the heat-melting coloring material layer of the present invention is not limited,
With respect to 100 parts (parts by weight, the same applies hereinafter) of the total solid content of the heat-melting coloring material layer, the heat-melting substance is 5 to 80 parts (more preferably 10 to 70 parts), and the colorant is 5 to 50 parts ( (more preferably 10 to 30 parts) and 3 to 80 parts (more preferably 5 to 15 parts) of polyethylene glycol diester.

In addition to the above-mentioned components, the heat-melting coloring material layer of the present invention may contain various additives. For example, vegetable oils such as castor oil, linseed oil, and olive oil, animal oils such as whale oil, and mineral oils are preferably used. It's fine.

In the heat-sensitive transfer recording medium of the present invention, techniques suitable for applying the heat-fusible colorant layer onto the support are known in the art, and these techniques can also be used in the present invention. For example, the heat-melting coloring material layer is a layer formed by hot-melt coating a dispersion thereof, or by solvent coating a coating liquid prepared by dissolving the dispersion in an appropriate solvent. Examples of the coating method for the heat-melting coloring material layer of the present invention include a reverse roll coater method, an extrusion coater method, a gravure coater method, and a wire bar coating method.
Any known technique can be adopted.

The thickness of the heat-melting coloring material layer of the present invention is preferably 3 to 50 g, m, more preferably 5 to 20 #L11, and the thickness is preferably 3 ALm or less, more preferably 1 It is considered to be below Le Peng.

In the present invention, adhesive layers include, for example, polyvinyl butyral resin, epoxy resin, polyester resin, vinyl chloride-vinyl acetate copolymer, acrylic resin, ethylene-
The thickness of the adhesive layer, which may be used alone or in combination of two or more of thermoplastic resins or thermosetting resins such as vinyl acetate copolymer, ethylene-ethyl acrylate copolymer, vinyl chloride resin, etc. is preferably 0.1 to 3.

More preferably 0.3 to tp countries. As a method for applying the adhesive layer to the support, any technique such as hot melt coating or solvent coating can be employed.

The support used in the thermal transfer recording medium of the present invention is preferably a support that has heat resistance strength, high dimensional stability and surface smoothness. It requires strength and dimensional stability to maintain the toughness of the support without becoming soft or plasticized, and surface smoothness is required to ensure that the coloring material layer containing a heat-fusible substance on the support has good transfer. Sufficient smoothness is desired to indicate the ratio.

Materials include, for example, papers such as plain paper, condenser paper, laminated paper, and coated paper, or polyethylene,
Resin films such as polyethylene terephthalate, polyester, polystyrene, polypropylene, polyimide, paper-resin film composites, metal sheets such as aluminum foil, etc. are all suitably used. The thickness of the support is usually about 60 gm or less, especially 2 to 2 gm, in order to obtain good thermal conductivity.
Further, in the thermal transfer recording medium of the present invention, the structure of the back side of the support is arbitrary,
A backing layer such as an anti-sticking layer may also be provided.

[Effects of the Invention] According to the present invention, low-energy printing is possible, the density decreases little with respect to the number of uses, and dye transfer images with high density, high resolution, and good printing quality can be produced many times. It is highly sensitive and can be used many times, especially for transfer paper with low surface smoothness. Furthermore, the thermal transfer recording medium of the present invention also has excellent blocking resistance.

[Examples] Examples of the present invention will be described below, but the present invention is not limited thereto. In addition, "department" used below means "
Parts by weight.

Example 1 Using a wire bar on a 3.5 JLm thick polyethylene terephthalate film, a dry film thickness of 1.0 g, a
An adhesive layer was obtained by applying an ethylene-ethyl acrylate copolymer (Much-6070 manufactured by Nippon Unicar Co., Ltd.) solution so that the color was +, and after drying, the following coloring material layer coating solution (dispersion using DiSilver) was applied to the wire. The dry film thickness is L using a bar.
After coating to give Qp-tr, the thermal transfer recording medium sample of the present invention (
A ribbon-like material with a width of 81 mm) was obtained.

Ethylene-vinyl acetate copolymer 11 parts (vinyl acetate content 20%) Oxidized wax 18 parts (Nippon Seiro Co., Ltd. NPS9125) Microcrystalline wax 40 parts Polyethylene glycol (molecule 1eooo) distearate
20 parts carbon black
15 copies of this thermal transfer recording medium sample■
was recorded (printed) on plain paper by applying an applied energy of 0.5 mJ/dat using a thermal printer (prototype 1 equipped with a thin-film line thermal head with a heating element density of 8 dots/am), and this was repeated twice. As the plain paper, commercially available high-quality paper (Beck smoothness: 100 sec) and copy paper (Beck smoothness: 30 sec) were used.The results are shown in Table 1.

Comparative Example 1 A comparative thermal transfer recording medium sample (2) was obtained in the same manner as in Example 1 except that polyethylene glycol distearate was not added. Thermal 11, -/I+ -/J- was used in the same manner as in Example 1 using this thermal transfer recording medium sample
-rsR1'e4F4+-p a) 3strokeJjLt-m
14.

Table 1 As is clear from Table 1 above, in sample ① of the present invention,
Not only 100sec high quality paper but also 30sec
cThe first and second reflection densities are 0 even for copying paper.
．． 9 or more, while the comparative sample ■ had a score of 30. se
Even for the copy paper of c, the density decrease from the first to the second application was large, and moreover, it took 100 seconds. Thermal transfer recording medium sample (2) was obtained with the following changes.

Oxidized wax (Nippon Kirou NPS9125) 20
Part microcrystalline wax 8 parts Polyethylene wax 12 parts Polyethylene glycol (molecular weight 8000) Dibehenate
20 parts Ethylene-ethyl acrylate copolymer (EA content 20%) 10 parts Paraffin wax 10 parts Carbon black 20 parts The above sample was printed on 30$8C paper in the same manner as in Example 1. The results are shown in Table 2.

Moreover, in the above Example 2, polyethylene glycol (
Thermal transfer recording medium samples ① to ② were obtained in the same manner except that the dibehenate (molecular weight eooo) was varied. Printing was carried out using a thermal printer in the same manner as in Example 1 using these thermal transfer recording medium samples ① to ②.

In addition, a blocking test was conducted on each sample. Blocking test samples polyethylene terephthalate film,! = a weight 1. ．． 17g/cm2
A load of 20% was applied thereto, and the sample was left at 45° C. and 20% RH for 2 days.

Thereafter, it was peeled off and its blocking resistance was examined. The results are shown in Table 2.

As is clear from the table above, the samples of the present invention have excellent blocking resistance, especially when the diester part of the polyethylene glycol diester has a large number of carbon atoms and the ethylene oxide part has a high molecular weight. It can be seen that blocking properties are particularly good. It can be seen that when the polyethylene glycol diester is not contained, the concentration decreases significantly.

Claims (1)

[Scope of Claims] A heat-sensitive transfer recording medium having a heat-melting coloring material layer on a support via an adhesive layer, wherein the heat-melting coloring material layer comprises polyethylene glycol diester and at least one compound selected from the following compound group. 1. A heat-sensitive transfer recording medium characterized by containing a heat-melting substance of various types. [Compound group] Animal waxes Vegetable waxes Mineral waxes Petroleum waxes Synthetic hydrocarbon waxes Modified waxes