JPS6183096A - Thermal transfer ink - Google Patents

Abstract

PURPOSE:To obtain thermal transfer ink excellent in a thermal transfer property and capable of transferring a character or shape having a sharp contour, by using a vinyl polymer with a specific m.p. and m.p. width as the binder component of the thermal transfer ink. CONSTITUTION:A vinyl polymer used as a binder component has a m.p. of 50-below 100 deg.C and a m.p. width of 4.5 deg.C or less and comprises one obtained from a monomer such as a vinyl compound or a copolymer thereof and a homopolymer of a radical polymerizable unsaturated monomer having a 17C or more long chain alkyl group or a copolymer comprising different radical polymerizable unsaturated monomers is especially pref. Other additives are mixed with 99-20wt% of the binder comprising said vinyl copolymer and 1-80wt% of a colorant if necessary to obtain thermal transfer ink.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an ink for forming a thermal transfer ink layer on a thermal transfer sheet, that is, a thermal transfer ink.

[Conventional technology]

The thermal transfer ink layer of the thermal transfer cartridge used in the thermal transfer recording method was generally formed with an ink made by melting and kneading a coloring agent into a binder component made of wax such as natural wax or synthetic wax. .

[Problem that the invention seeks to solve]

By the way, in the thermal transfer ink containing the wax and colorant as composition components, since the wax in the ink component is a mixture of compounds with different molecular weights, the thermal transfer ink layer formed with the thermal transfer ink is The binder component inside has a wide temperature range (melting point width) from the start of melting to the completion of melting by heating, from 5 to 10 °C,
Therefore, in a thermal recording method using a thermal transfer plate having a thermal transfer ink layer using the thermal transfer ink, not only the thermal transfer may be insufficient depending on the temperature of the thermal head used, but also the thermal transfer near the printed area may become insufficient. It has the disadvantage that even the wax component with a relatively low melting point in the thermal transfer ink layer melts, which causes smearing of the printed characters, which makes it difficult to transfer characters and shapes with clear outlines. are doing.

Furthermore, when natural wax is used as the wax component in the thermal transfer ink, the composition varies depending on the place of production, weather conditions, etc., so there is also the drawback that it is difficult to mass-produce a thermal transfer ink of constant quality.

Also, wax is soft at room temperature and easily scratches, so
It also has the disadvantage of being complicated to handle.

On the other hand, the thermal transfer ink of the present invention does not contain the wax component in one of its components, has excellent thermal transfer properties, and can obtain a thermal transfer layer with clearly defined characters and shapes. be.

Means for Solving Point C] The thermal transfer ink of the present invention has a binder component in the ink having a melting point of 50°C or higher and lower than 100°C, and a melting point width of 4.5°C or lower. It is made of vinyl polymer.

The vinyl polymer serving as the binder component in the thermal transfer ink of the present invention has a melting point of 50°C or higher and lower than 100°C, and usually has a molecular weight of L000 to loo, ooo.
degree, melt viscosity 10-3. OOOαP is used.

Since it is necessary that the melting point width is adjusted to 4.5° C. or less, a vinyl polymer having a substantially uniform molecular weight is used.

Examples of the vinyl polymer as the binder component include derivatives of acrylic acid and methacrylic acid, allyl compounds,
vinyl ether, vinyl ester, vinyl halide,
Vinyl polymers obtained from monomers such as vinyl compounds containing other aromatic rings or heterocycles, as well as copolymers thereof, are used, but in particular, radical polymers having long-chain alkyl groups of 17 or more carbon atoms are used. When a homopolymer of a radically polymerizable unsaturated monomer or a copolymer of the radically polymerizable unsaturated monomers is used, the vinyl polymer as a binder component in the thermal transfer ink of the present invention is specified. It is extremely easy to produce a vinyl polymer that satisfies the requirements of having a melting point of 50° C. or more and less than 100° C. and a melting point width of 4.5° C. or less. This homopolymer of the radically polymerizable unsaturated monomer having a long chain alkyl group with 17 or more carbon atoms or the copolymer of the radically polymerizable unsaturated monomers has a narrow melting point width, and is extremely However, this property of the polymer is due to the fact that the alkyl group constituting the ester in one molecule is a long chain with 17 or more carbon atoms, so the crystallinity within the polymer molecule is low. is extremely high, and it is presumed that this is because the alkyl group loses its crystallinity and becomes fluid during heating.

The radically polymerizable unsaturated monomer having a long chain alkyl group having 17 or more carbon atoms is generally.

An acrylic ester or methacrylic ester of a higher alcohol having 17 or more carbon atoms represented by the general formula % 1 For example, heptadyl alcohol.

Stearyl alcohol, nonate/ru alcohol.

Esters of acrylic acid or methacrylic acid and alcohols such as eicoful alcohol, he/eiko/ru alcohol, toconol alcohol, tric/ru alcohol, and -rtraconol alcohol are used.

The vinyl polymer which is a suitable binder component is prepared by polymerization using the above-mentioned radically polymerizable unsaturated monomer having a long chain alkyl group of 17 or more carbon atoms, such as ordinary solution polymerization, emulsion polymerization, pearl polymerization, etc. obtained, but 1 molecular weight L0
00 to about 100,000 is most preferred.

The thermal transfer ink of the present invention contains the vinyl polymer as a binder component, that is, a vinyl polymer having a melting point of 50°C or more and less than 100°C and a melting point width of 4.5°C or less. The other compositional components are no different from conventional thermal transfer inks that use wax as a binder.

For example, the colorant as a component in the thermal transfer ink may include organic or inorganic dyes or pigments.
The ink having the characteristics as an ink for constituting the thermal transfer ink layer is preferably one that exhibits sufficient color density and does not discolor or fade due to light, heat, humidity, etc. Also, as a colorant or a substance equivalent to a colorant, it is colorless when not heated.

One that develops color when heated and maintains its hue, and one that has the property of causing the surface of the transfer object to develop color when it comes into contact with a substance applied to the surface of the transfer object. Of course, it is also possible to use the following. In addition, the ratio of the colorant and the vinyl polymer as the binder component in this thermal transfer ink is 1 to 80% by weight of the colorant:
Binder component 99-20% by weight, preferably colorant 2
-20% by weight, and the binder component is about 98-80% by weight.

Further, other compositional components which may be surface-added as necessary to constitute the thermal transfer ink of the present invention include: 1, for example, a softening agent such as mineral oil or vegetable oil, and a thermal conductivity improver such as metal powder. .

Including extender pigments such as Micro Norica, carunium carbonate or kaolin, transferability improvers such as polyhydric alcohol,
Chy/lene, toluene, trichlene, white spirit, ethyl acetate, n-butyl acetate, methanol, ethanol, inopropanol, n-butanol, ethyl/chlorohexane, ethyl selonorp, butyl selonol.

7. There are solvents or diluents such as clohexanone.

The structure of a thermal transfer notebook obtained by using the thermal transfer ink of the present invention having the above-described structure will be described below.

The base material on which the heat transfer ink layer is formed using the heat transfer ink of the present invention, that is, the base material for a heat-sensitive transfer notebook, includes the base material 1 for conventional heat-sensitive transfer sheets, such as polyester resin, polypropylene resin, cellulose resin, etc. In addition to resin films made of 9F resin, polysteel/resin, polycarbonate resin, polyimide resin, etc., cellophane, grain paper, capacitor paper, form paper, India 7 paper, metal foil, composites of the previous types of base materials, etc. can be used.

Further, specific examples of the composite include aluminum/paper composite, metal-deposited paper, etc. A metal-deposited plastic film or the like is used. Furthermore, the thickness of the base material is better from the viewpoint of thermal conductivity to the thermal transfer ink layer formed by the thermal transfer ink, but if it is less than 2 μm, not only the strength will be insufficient but also the handling will be difficult. is getting worse and still 5
If it exceeds 0 μm, the resolution of the printed area, which is a thermal transfer layer obtained by a thermal transfer recording method, will decrease. Therefore, usually 2
A material with a diameter of about 50 μm is used.

Incidentally, one side of the base material, that is, the side that comes into contact with the thermal head when used as a thermal transfer sheet.

/) Add slip properties by applying a slip agent such as Noko-7 oil, or form a heat-resistant resin layer to prevent the thermal head from sticking to the base material during use. Furthermore, it is of course possible to add a lubricant such as talc or fluororesin powder to the heat-resistant resin layer to further improve the anti-sticking performance.

Methods for applying the thermal transfer ink of the present invention on one side of the substrate include a hot melt coating method in which the composition constituting the thermal transfer ink is heated and melted while being applied, gravure coating, o- Coating means such as le coat, air knife coat, kiss coat, spray coat, continuous coat, dip coat, spin/nare coat, whisky coat, brush coat, solid coat by Fluxscreen, wire bar code, 70-coat, gravure printing, Printing methods such as gravure offset printing, lithographic offset printing, die-line printing, intaglio printing, and flux screen printing can be used. Regarding the thickness of the thermal transfer ink layer formed by applying thermal transfer ink to one side of the base material, if this is less than 0.1 μm, the printed portion of the thermal transfer layer obtained by the thermal transfer recording method will deteriorate. In many cases, the purpose of recording is not achieved due to insufficient flexibility, and if it exceeds 30μ, heat conduction to the entire thermal transfer ink layer becomes insufficient during thermal transfer recording, and the purpose of thermal transfer recording is not achieved. Generally, 0.1 to 30 μm, preferably 1 to 20 μm, due to reasons such as failure to achieve
It is configured to the extent that it is customary.

C action] The thermal transfer ink of the present invention contains, as a binder component in the ink, a vinyl-based small polymer having a melting point of 50°C or more and less than 100°C and a melting point width of 4.5°C or less. In the thermal transfer recording method carried out using a thermal transfer notebook having a thermal transfer ink layer formed of the above-mentioned thermal transfer ink, the thermal transfer ink layer has good thermal transfer characteristics and high This has the effect of being able to reproduce the thermal pattern from the thermal head extremely faithfully in print recording that requires high resolution.

In particular, as the vinyl polymer serving as the binder component, a homopolymer of a radically polymerizable unsaturated monomer having a long chain alkyl group of 17 or more carbon atoms or a homopolymer of a radically polymerizable unsaturated monomer having a long chain alkyl group of 17 or more carbon atoms or When using a copolymer,
It is presumed that this is because the alkyl group constituting the ester in the molecule of the polymer is long-chained, so that the crystallinity within the molecule of the polymer is extremely high. The melting point range of barrel vinyl polymers is extremely wide/
The grain width is extremely small. Therefore, in thermal transfer ink containing this vinyl polymer as a binder component, the above-mentioned thermal transfer recording allows characters and figures with extremely high resolution, that is, characters and figures with clear outlines, to be obtained as transferred images. This effect is produced.

〔Example〕

Hereinafter, the specific structure of the thermal transfer ink of the present invention will be explained with reference to examples, and the performance of a thermal transfer notebook having a thermal transfer ink layer formed with the ink will be described.

Example 1 The following composition [1] was refluxed for 2 hours to obtain a vinyl polymer (A
) was obtained.

Composition [1] Stearyl acrylate °-100 parts by weight Tolue/
-... 150 parts by weight α,α'-azobisinobutyronitrile 0.2 parts by weight .The melting point is 53°C and the melting point width is 4.0°C.

Next, the following composition [II] was stirred at room temperature in a ball mill to obtain gravure ink (a), which is an example of the thermal transfer ink of the present invention and has a viscosity of 300 C.P at 25°C.

Composition [11] Vinyl polymer (A)... 25 parts by weight Red pigment (C1,15850 l... 5 parts by weight Toluene... 70 parts by weight,
The gravure ink (a) was applied to one surface of a 6 μm thick polyester film, which is the base material of the thermal transfer sheet, by a gravure coating method and dried to a thickness of 3 μm.
Thermal transfer 7-
I got it.

Using the heat-sensitive transfer sheet thus obtained, printing was performed using a printing machine equipped with a thermal head (Toko Co., Ltd. +=I;+a+OJ), and a red print with a clear outline was obtained.

Example 2 The following composition (iii) was refluxed for 2 hours to obtain a vinyl polymer CB) which is a binder component in the thermal transfer ink of the present invention.

Composition (iii) Behenyl acrylate - 100 parts by weight Toluene/
...100 parts by weight α,α'-azobisinobutyronitrile...0.2 parts by weight, the obtained vinyl polymer CB) had an average molecular weight of 3000.
The melting point is 60°C and the melting point width is 3.5°C.

Next, the following composition [1] was stirred at room temperature in a ball mill to obtain gravure ink (b), which is an example of the thermal transfer ink of the present invention and has a viscosity of 300 C.P at 25°C.

Composition [1■] Vinyl polymer CB) 25 parts by weight Blue pigment (C, 1,74160) 5 parts by weight Toluene 70 parts by weight The gravure ink (b) is applied to one surface of a polyester film with a thickness of 6 μm as a base material by a gravure coating method and dried to form a thermal transfer ink layer with a thickness of 3 μm, thereby producing a heat-sensitive transfer notebook. Obtained.

When the thermal transfer notebook thus obtained was printed using a printing machine equipped with a thermal gutter (manufactured by Toshiba Corporation: F1610), a blue print with a clear outline was obtained.

〔effect〕

The thermal transfer ink of the present invention has the above-mentioned structure, and has a melting point of 50°C or more and less than 100°C, and a bi/vinyl composite having a melting point range of 4.5°C or less. Since it contains a goo component, the effect of the binder component in the ink component provides extremely excellent thermal transfer properties.

Claims (2)

[Claims] (1) A thermal transfer ink characterized by containing a binder component made of a vinyl polymer having a melting point of 50° C. or more and less than 100° C. and a melting point range of 4.5° C. or less. (2) A patent in which the vinyl polymer is a homopolymer of a radically polymerizable unsaturated monomer having a long chain alkyl group with 17 or more carbon atoms or a copolymer of the radically polymerizable unsaturated monomers. The thermal transfer ink according to claim 1.