JPS6282086A - Thermal transfer recording medium - Google Patents

Abstract

PURPOSE:To provide a thermal transfer recording medium generating no blocking during preservation and not contaminating a thermal head during use and prevented from a sticking phenomenon, by providing a layer containing at least one silicone modified urethane resin on a support at the side opposite to a coloring material layer. CONSTITUTION:In a thermal transfer recording medium wherein at least one coloring material layer containing a heat-meltable substance is provided on a support, a layer (packing layer) containing at least one silicone modified urethane resin is provided on the support at the side opposite to the coloring material layer. This silicone modified urethane resin is a copolymer of polyurethane obtained from a prepolymer having at least one cyclic structure in the constitutional unit thereof and dissisocyanate and a silicone resin. The silicon modified urethane resin contained in the packing layer is obtained by copolymerizing polyurethane and the silicone resin but polyurethane is obtained from the prepolymer having at least one cyclic structure in the constitutional unit thereof and diisocyanate.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a thermal transfer recording medium, and more specifically, the present invention relates to a thermal transfer recording medium that does not cause blocking during storage, does not contaminate a thermal head during use, and prevents sticking phenomenon. The present invention relates to a thermal transfer recording medium that can be used.

[Prior art]

As one of the techniques related to heat-sensitive recording media, a technique has been described in which a silicone-modified wax is used as a protective layer. However, thermal paper used as a recording medium cannot prevent printed (recorded) images from being tampered with, and has the drawback that the printed (recorded) images have poor storage stability because they are easily colored by heat or organic solvents. . On the other hand, a type of thermal transfer recording medium using a heat-melting substance is known as a recording medium that is highly tamper-resistant and preservable.

However, in the melt transfer type thermal transfer recording medium that uses a polymer film such as a polyethylene terephthalate film as a support, a part of the film support is melted by the thermal head heated during recording and is fused to the thermal head. Sometimes I wear it. This phenomenon is called a sticking phenomenon, and it significantly deteriorates the recording quality and eventually causes the film support to become stuck to the thermal head, making it impossible to feed the thermal transfer recording medium.

In order to prevent this stinking phenomenon, it is possible to use paper with excellent heat resistance such as condenser paper for the support, but if such paper is used, heat conduction from the thermal head is poor, so the thermal head The power applied to the thermal head must be increased, which has the disadvantage of significantly shortening the life of the thermal head.

On the other hand, as a technique for preventing the sticking phenomenon, there is a technique using a backing layer. For example, JP-A-55-746
No. 7 proposes providing a heat-resistant protective film made of silicone resin or the like on the film support, but this method has the disadvantage that the thermal head will rub when recording for a long time because the friction with the thermal head is large. Therefore,
No. 8-171992 proposes the use of waxes in combination with thermoplastic resins in order to improve the lubricity of the backing layer. However, when the paraffin-based or ethylene-based waxes disclosed therein are used, In addition to the drawback that the head gets dirty, there is also a drawback that the thermal transfer recording medium causes blocking during its storage. Furthermore, JP-A-56-155794 proposes providing a resin layer containing a highly slippery inorganic pigment on a film support, but the inorganic pigment peeled off from the resin layer contaminates the thermal head. I saw some shortcomings.

[Purpose of the invention]

An object of the present invention is to provide a thermal transfer recording medium that does not cause blocking during storage, does not contaminate a thermal head during use, and is prevented from sticking.

Another object of the present invention is to provide a thermal transfer recording medium that has good adhesion to a film support and is free from the risk of adhesion to a hot roll during production.

[Structure of the invention]

As a result of extensive research, the present inventor has discovered that a heat-sensitive transfer recording medium having at least one coloring material layer containing a heat-fusible substance on a support has the following silicone-modified material on the support opposite to the coloring material layer. The object of the present invention could be achieved with a small amount of urethane resin.

Silicon modified urethane resin: at least 1 in the constituent unit
A copolymer of polyurethane and silicone resin obtained from a prepolymer with a cyclic structure and a diisocyanate.

The present invention will be explained in more detail below.

The silicone-modified urethane resin contained in the backing layer is obtained by copolymerizing polyurethane and silicone resin. It has its features.

Examples of this prepolymer include polyester and polyether, and polyester is particularly preferred. Polyester manufacturing methods include esterification reactions between dicarboxylic acids and diols, transesterification reactions between dicarboxylic acid esters and diols, metathesis reactions between dicarboxylic acid chlorides and diols, and ring-opening condensation reactions between dicarboxylic acid anhydrides and alkylene oxides. Generally, an esterification reaction between a dicarboxylic acid and a diol is used.

The combination of dicarboxylic acid and diol used is 1
There may be a plurality of types, but it is necessary that at least one dicarboxylic acid or/and diol has a cyclic structure. The cyclic structure may be benzene, naphthalene, cycloalkane, etc., but benzene and cyclohexane, which are six-membered rings, are preferred.

Preferred dicarboxylic acids include the following.

Maleic anhydride Fumaric acid Citraconic acid Itaconic acid Tetrachlorophthalic anhydride Hetacetic anhydride Tetrabromophthalic anhydride Inphthalic anhydride Terephthalic acid Endomethylene Tetrahydrophthalic anhydride Tetrahydrophthalic anhydride Hexahydrophthalic anhydride Succinic acid Adipic acid Azelaic acid Sebacic acid Anthracene - Maleic anhydride adduct Rosin - Maleic anhydride adduct Preferred diols include the following.

Ethylene glycol Propylene glycol 1.4-Butanediol 1.3-Butanediol 2.3-Butanediol Diethylene glycol Dipropylene glycol Triethylene glycol 1.5-bentanediol 1.6-Hexanediol Neopentyl glycol 2.2.4- ) Limethylpencunediol-1,3-hydrogenated bisphenol A Pentaerythritol diallyl ether trimethylene glycol 2-ethyl-1,3-hexanediol Cyclohexanone dimethanol The diisocyanates that can be reacted with polyester to give polyurethane include: to p-fluorene diisocyanate, 2.4-)fluorene diisocyanate, 1,5
-Naphthalene diisocyanate, tridene diisocyanate, diphenylmethane diisocyanate, hexamethylene diisocyanate, m-xylylene diisocyanate, dianisidine diisocyanate, and the like.

As the silicone resin to be copolymerized with polyurethane, specifically, polydimethylsiloxane or alkyl A4. phenyl group,
Examples include silicone resins into which polyoxyalkyl groups, fluoroalkyl groups, amino groups, epoxy groups, mercapto groups, carboxyl groups, etc. have been introduced, and copolymers of these modified silicone resins and polydimethylsiloxane.

Representative silicone resins are shown below.

e e In the above formula, α, β, a, b, and c are integers of 0 or more,
α and β are never 0 at the same time.

R1 is an alkyl group, R2 has 1 to 40 carbon atoms/l/
* Represents /l/ group or other organic group. Also Me
indicates a methyl group.

Specific examples of the silicone-modified urethane resin preferably used in the present invention are shown below, but the invention is not limited thereto.

In the formula, R is the ratio of polyurethane to silicone resin: m: n-99
:1 to 40:60, preferably m:n='15
: 5 to 60:40 13 Although the silicone-modified urethane resin according to the present invention can sufficiently achieve the object of the present invention without crosslinking, the effect is further increased if crosslinked. The crosslinking method is amine, water,
Examples include a method of crosslinking a urethane portion with a diol or the like, and a method of crosslinking a silicone portion with a silane coupling agent or the like.

The banking layer of the present invention may have any thickness as long as it is 0.01 μm or more. In practice, it is 0.03 to 1.
0 μm is preferable.

The film support used in the present invention may be a resin film with excellent surface smoothness and dimensional stability, such as polyethylene terephthalate film, polyimide film,
Resin films such as polycarbonate films (polymer,
Examples thereof include copolymers and terpolymers. Although the thickness of these film supports is not limited, it is preferably about 2 to 15 μm. These supports are subjected to treatments such as corona discharge, glow discharge, other electron impact, flame treatment, ultraviolet irradiation, oxidation treatment, saponification treatment, and surface roughening to improve the adhesion of the backing layer of the present invention. may be applied, or may be undercoated.

The backing layer of the present invention may be coated on a film support by, for example, applying a backing layer composition as appropriate. The solvent used at this time may be any solvent that can dissolve or disperse each component of the present invention to form a coating solution, such as paraffinic solvents such as n-hexane, ligroin, and isoparaffin, aromatic solvents such as toluene, xylene, etc. solvents, ketone solvents such as acetone, methyl ethyl ketone, methyl imbutyl ketone, alcohol solvents such as methanol, ethanol, propatool, butanol, ester solvents such as ethyl acetate, special solvents such as dimethylformamide, dimethyl sulfoxide, etc. Examples include organic solvents, and mixed solvents thereof may also be used. For coating, any coating technique can be employed, such as a reverse roll coater method, an extrusion coater method, a gravure coater method, or a wire bar coating method.

The color material layer of the present invention will be explained below.

The coloring agent contained in the coloring material layer of the present invention may be any inorganic pigment, organic pigment, or organic dye.

Examples of inorganic pigments include titanium dioxide, carbon black, cadmium, iron oxides and chromates of lead, zinc, barium and calcium. Organic pigments include azo, thioindigo, and anthraquinone.

Anthurone, triphenedioxazine pigments,
Vano I dye pigments, phthalocyanine 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.

A heat-fusible substance is used in the coloring material layer of the present invention.

The melting point of heat-melting substances (value measured by Yanagimoto MPJ-2 type)
It is preferably a solid or semi-solid substance with a temperature of 10 to 120°C. Specific examples include carnauba wax,
Plant waxes such as wood wax, auriculie wax, Nispar wax, animal waxes such as beeswax, insect wax, shellac wax, spermaceti wax, petroleum waxes such as paraffin wax, microcrystalline wax, ester wax, acid wax, montan wax, osichelite, In addition to waxes such as mineral waxes such as shellac; higher fatty acids such as palmitic acid, stearic acid, margaric acid, and behenic acid; palmityl,
Higher alcohols such as alcohol, stearyl alcohol, behenyl alcohol, marganyl alcohol, myricyl alcohol, eicosanol; cetyl palmitate,
Higher fatty acid esters such as myricyl palmitate, cetyl stearate, myricyl stearate: acetamide,
Amides such as propionic acid amide, palmitic acid amide, stearic acid amide, amide wax; ester gum, rosin derivatives such as rosin maleic acid resin, rosin phenol resin, hydrogenated rosin; phenolic resin, terpene resin, cyclopentadiene resin , aromatic resins, and other polymeric compounds with a softening point of 50 to 120°C; stearylamine, behenylamine, valmitylamine, etc. KR amines; include polyethylene oxides such as polyethylene glycol 4000 and polyethylene glycol 6000, and these may be used alone or in combination.

Although the composition ratio of the coloring material layer of the present invention is not limited, the heat-melting substance is 50 to 90 parts and the coloring agent is 5 to 20 parts to 1,100 parts (by weight, the same applies hereinafter) in total of the coloring material layer. The content of the resin is 0 to 30 parts (preferably 5 to 30 parts).

The color material layer of the present invention may contain various additives in addition to the above components. For example, as a softener, castor oil,
Vegetable oils such as linseed oil, olive oil, animal oils such as whale oil and mineral oils may be suitably used.

Note that the coloring material layer has a thickness of 15 μm or less, preferably 1 to 10 μm.
It is better to be considered as

〔Effect of the invention〕

According to the present invention, in a thermal transfer recording medium having a coloring material layer containing a heat-melting substance on one side of a film support and a backing layer on the other side, the backing layer has a cyclic structure in its constituent units. By containing a silicone-modified urethane resin, the above-mentioned objects of the present invention can be achieved, and in particular, so-called maintenance-free properties can be achieved.

〔Example〕

Examples will be given below, but the embodiments of the present invention are not limited to these (. Note that "parts" used below indicate "parts by weight".

Coating solutions for backing layers of the present invention and comparison were prepared as follows.

Synthesis of urethane polymer prepolymer from the composition 1. ,,],]A urethane polymer was obtained by reacting with 5-naphthalene diisocyanate. Furthermore, 80 mol% of the urethane polymer was reacted with 20 mol% of a silicone polymer (polydimethylsiloxane) to obtain a silicone-modified urethane resin, which was diluted to give methyl ethyl ketone/toluene=9/
1 (volume ratio) A coating liquid A having a solid content concentration of 1% was prepared.

Cyclohexane dimetatool: 18 mol% A urethane polymer prepolymer was synthesized from the above composition, and reacted with diphenylmethylene diisocyanate to obtain a urethane polymer. After this, coating liquid B was prepared in the same manner as in the case of coating liquid A.

A prepolymer of urethane polymer is synthesized from the above composition, and from this point onwards, the same method as in the case of preparing the coating liquid C is applied.
It was created.

The above composition was dissolved in methyl ethyl ketone to prepare a coating liquid with a solid content concentration of 1%.

On the other hand, prior to this, a coloring material layer composition having the following composition was kept at 120° C., molten, and applied to one side of a 3.5 μm polyester film with a wire bar to a thickness of 3.5 μm.

Next, the coating liquid A-D was applied to the opposite side of the film coated with the coloring material layer to a thickness of 0.1 μm to form a backing layer. Using the obtained thermal transfer recording medium,
Blocking, anti-sticking, and hot roll contact tests were conducted. The results are shown in Table 1.

(Blocking test) Thermal transfer recording medium was 111 m wide with a tension of 9 SI and an outer diameter of 1
It was wound around a core in the order of 7 and placed in an atmosphere at 55° C. for 3 days, and then unwound to observe how the coloring material layer was transferred to the backing layer due to blocking.

(Sticking prevention test) Recording was carried out on a thermal transfer recording medium using a thermal head with an element density of 8 pieces/heating element under the conditions that the applied power was 0.7 W per heating element and the application time was 2.3 milliseconds. Observation of quality and anti-sticking effect O The surface on which the backing layer was applied was brought into contact with a chrome plated roll at 120° C. The state at this time was observed.

Table 1

Claims (1)

[Claims] In a thermal transfer recording medium having at least one coloring material layer containing a heat-melting substance on a support, the following silicon-modified urethane resin is provided on the support opposite to the coloring material layer. A thermal transfer recording medium characterized by having a layer containing at least one type. Silicon modified urethane resin: at least 1 in the constituent unit
A copolymer of polyurethane and silicone resin obtained from a prepolymer with a cyclic structure and diisocyanate.