JPH0712754B2 - Thermal transfer recording medium - Google Patents

Description

TECHNICAL FIELD The present invention relates to a thermal transfer recording medium, and more specifically, it does not cause blocking during storage, does not contaminate a thermal head during use, and prevents sticking phenomenon. The present invention relates to a heat-sensitive transfer recording medium.

[Prior art]

Thermal paper is widely known as one of the technologies relating to a thermal recording medium from the viewpoint of easy handling, and for example, JP-A-57-2795 discloses a technology using a silicone-modified wax as a protective layer together with a binder. Have been described. However, thermal paper as such a recording medium is printed (recorded).
There is a drawback that the storability of the printed (recorded) image is poor because the image cannot be tampered with and the color is easily developed by heat or an organic solvent. On the other hand, as a recording medium excellent in tamper resistance and storage stability, a thermal transfer recording medium of a type using a heat-melting substance is known.

However, in the melt transfer type thermal transfer recording medium using a polymer film such as a polyethylene terephthalate film as a support, a part of the film support is melted and fused to the thermal head by the thermal head heated at the time of recording. Sometimes. This phenomenon is called the sticking phenomenon, and the recording quality is remarkably deteriorated, and finally the film support burns on the thermal head, making it impossible to feed the thermal transfer recording medium.

In order to prevent this sticking phenomenon, a paper having excellent heat resistance such as condenser paper may be used for the support. However, when such a paper is used, heat conduction from the thermal head is poor, so It is necessary to increase the applied power, and there is a drawback that the life of the thermal head is significantly impaired.

On the other hand, as a technique for preventing the sticking phenomenon, there is a technique using a backing layer. For example, Japanese Patent Laid-Open No. 55-7467 proposes to provide a heat-resistant protective film such as a silicone resin on the film support. There is a drawback that it does. Therefore, JP-A-58-1719
No. 92 proposes that waxes are used in combination with a thermoplastic resin in order to improve the slipperiness of the backing layer. However, when the waxes of paraffin type and ethylene type disclosed herein are used, the head is Not only is there a drawback of becoming dirty, but there is a drawback that the thermal transfer recording medium causes blocking during storage. In addition, JP-A-56-
No. 155794 proposes that a resin layer containing an inorganic pigment having high lubricity is provided on a film support, but there is a drawback that the inorganic pigment peeled from the resin layer contaminates the thermal head.

[Object 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 the thermal head during use, and prevents the sticking phenomenon.

Another object of the present invention is to provide a heat-sensitive transfer recording medium which has good adhesiveness to a film support and which is not likely to adhere to a heat roll during production.

[Structure of Invention]

As a result of earnest studies, the present inventors have found 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 silicon modification on the support opposite to the coloring material layer. By having a layer containing at least one urethane resin (hereinafter referred to as a backing layer), the above object of the present invention can be achieved.

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

Hereinafter, the present invention will be described more specifically.

The silicone-modified urethane resin contained in the backing layer is obtained by copolymerization of polyurethane and silicone resin, but it is characterized in that polyurethane is obtained from a prepolymer having at least one cyclic structure in the constitutional unit and diisocyanate. is there.

Examples of the prepolymer include polyester and polyether, and polyester is particularly preferable. Polyester production methods include esterification reaction of dicarboxylic acid and diol, transesterification reaction of dicarboxylic acid ester and diol, metathesis reaction of dicarboxylic acid chloride and diol, ring-opening condensation reaction of dicarboxylic acid anhydride and alkylene oxide. Generally, an esterification reaction of a dicarboxylic acid and a diol is used.

The combination of dicarboxylic acid and diol used is 1
There is no particular restriction on the type, but it is necessary that at least one dicarboxylic acid or / and diol has a cyclic structure. As the cyclic structure, any of benzene, naphthalene, cycloalkane and the like may be present, but 6-membered ring benzene and cyclohexane are preferable.

Specific examples of preferred dicarboxylic acids include the following.

Maleic anhydride fumaric acid citraconic acid itaconic acid tetrachlorophthalic anhydride het acid tetrabromophthalic anhydride phthalic anhydride isophthalic acid 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 Specific examples of preferable 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-pentanediol 1,6-hexanediol neopentyl glycol 2,2,4- Trimethylpentanediol-1,3-hydrogenated bisphenol A 2,2-di (4-hydroxypropoxyphenyl) propane pentaerythritol diallyl ether trimethylene glycol 2-ethyl-1,3-hexanediol cyclohexanone dimethanol Reacted with polyester Specific examples of the diisocyanate giving polyurethane include p-phenylene diisocyanate, 2,4-toluene diisocyanate, 1,5-naphthalene diisocyanate, tridene diisocyanate,
Examples thereof include diphenylmethane diisocyanate, hexamethylene diisocyanate, m-xylylene diisocyanate, and dianisidine diisocyanate.

As the silicone resin to be copolymerized with polyurethane, specifically, an alkyl group, a phenyl group, instead of a methyl group of polydimethylsiloxane or polydimethylsiloxane,
Examples thereof include a silicone resin introduced with a polyoxyalkyl group, a fluoroalkyl group, an amino group, an epoxy group, a mercapto group, a carboxyl group, or a copolymer of these modified silicone resins and polydimethylsiloxane.

Typical silicone resins are shown below.

In the above formula, α, β, a, b, c are integers of 0 or more, and α and β cannot be 0 at the same time. R ₁ is an alkyl group, R ₂
Represents an alkyl group having 1 to 40 carbon atoms or another organic group. Me represents 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.

Where R is The ratio of polyurethane to silicone resin is m: n = 99: 1 to 40: 6
0, preferably m: n = 95: 5 to 60:40.

The silicone-modified urethane resin according to the present invention can sufficiently achieve the object of the present invention without being crosslinked, but the effect is further increased by crosslinking. The method of crosslinking is amine, water,
Examples thereof include a method of crosslinking the urethane portion with a diol or the like, and a method of crosslinking the silicon portion with a silane coupling agent or the like.

The backing layer of the present invention may have any thickness as long as it is 0.01 μm or more. Practically, 0.03 to 1.0 μm is preferable.

The film support used in the present invention may be a resin film having excellent surface smoothness and dimensional stability, a polyethylene terephthalate film, a polyimide film,
Resin film such as polycarbonate film (polymer,
Specific examples thereof include copolymers and terpolymers). The thickness of these film supports is not limited, but is preferably about 2 to 15 μm. In order to enhance the adhesiveness of the backing layer of the present invention, these supports are subjected to corona discharge, glow discharge, other electron impact, flame treatment, ultraviolet irradiation, oxidation treatment, saponification treatment, roughening treatment, etc. on the support surface. May be applied or may be subjected to undercoating.

The method of applying the backing layer of the present invention to the film support may be, for example, solvent coating of a coating solution in which the backing layer composition is dispersed in an appropriate solvent. The solvent used at this time may be any solvent that can dissolve or disperse the components of the present invention into a coating liquid, and for example, n
-Hexane, ligroin, paraffinic solvents such as isoparaffin, aromatic solvents such as toluene and xylene, ketone solvents such as acetone, methyl ethyl ketone and methyl isobutyl ketone, alcohol solvents such as methanol, ethanol, propanol and butanol, ethyl acetate And the like, organic solvents such as special solvents such as dimethylformamide and dimethylsulfoxide, and the like, and mixed solvents thereof may be used. At the time of coating, any coating technique such as a reverse roll coater method, an extrusion coater method, a gravure coater method or a wire bar coating method can be adopted.

Hereinafter, the color material layer of the present invention will be described.

The colorant contained in the color material layer of the present invention may be any one of an inorganic pigment, an organic pigment or an organic dye. Examples of 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 organic pigments include azo, thioindigo, anthraquinone, anthanthrone, triphendioxazine pigments, vat 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-meltable substance is used for the color material layer of the present invention. The melting point (measured by Yanagimoto MPJ-2 type) of heat-fusible substances is 40-120
It is preferably a solid or semi-solid substance at ° C. Specific examples include plant waxes such as carnauba wax, tree wax, auricurie wax, and espal wax, animal waxes such as beeswax, insect wax, shellac wax, whale wax, paraffin wax, microcrystalline wax, ester wax, acid wax, and the like. In addition to waxes such as mineral waxes such as petroleum wax, montan wax, ozokerite and ceresin; higher fatty acids such as palmitic acid, stearic acid, margaric acid and behenic acid; palmityl alcohol, stearyl alcohol, behenyl alcohol, marganyl alcohol, milliyl Higher alcohols such as sil alcohol and eicosanol; higher fatty acid esters such as cetyl palmitate, myricyl palmitate, cetyl stearate, myricyl stearate; acedamide, propionamide, amid palmitate Amides such as stearic acid amide and amide wax; rosin derivatives such as ester gum, rosin maleic acid resin, rosin phenol resin, hydrogenated rosin; softening point of phenol resin, terpene resin, cyclopentadiene resin, aromatic resin, etc. Polymer compounds at 50 to 120 ° C; higher amines such as stearylamine, behenylamine, palmitylamine; polyethylene glycol
Examples thereof include polyethylene oxide such as 4000 and polyethylene glycol 6000. These may be used alone or in combination.

The composition ratio of the color material layer of the present invention is not limited, but 50 to 90 parts of the heat-fusible substance and 5 to 20 parts of the colorant are used with respect to the total amount of the color material layer of 100 parts (parts by weight, hereinafter the same). , And the resin is 0 to 30 parts (preferably 5 to 30 parts).

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

The color material layer has a thickness of 15 μm or less, preferably 1 to 10 μm.

〔The invention's effect〕

According to the present invention, in a thermal transfer recording medium having a color material layer containing a heat-fusible substance on one surface of a film support and a backing layer on the other surface, the backing layer has an annular structure in the constitutional unit. Since the silicone-modified urethane resin is contained, there is an effect that the above-mentioned object of the present invention can be achieved and, in particular, so-called maintenance-free property can be realized.

〔Example〕

Examples will be given below, but the embodiments of the present invention are not limited thereto. The term "parts" used below means "parts by weight".

The coating solutions for the backing layer of the present invention and the comparative example were prepared as follows.

Preparation of coating liquid A A urethane polymer prepolymer was synthesized from the above composition and reacted with 1,5-naphthalene diisocyanate to obtain a urethane polymer. 80 mol% of the urethane polymer
And 20 mol% of a silicon polymer (polydimethylsiloxane) were reacted to obtain a silicone-modified urethane resin, which was diluted to prepare a coating liquid A having a solid content concentration of 1% methylethylketone / toluene = 9/1 (volume ratio).

Preparation of coating liquid B A urethane polymer prepolymer was synthesized from the above composition and reacted with diphenylmethylene diisocyanate to obtain a urethane polymer. After that, the coating liquid B was prepared in the same manner as the coating liquid A.

Preparation of coating liquid C A urethane polymer prepolymer was synthesized from the above composition, and thereafter, the coating solution C was prepared in the same manner as the coating solution A.
It was created.

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

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

Then, the coating liquids A to D were applied to the surface on the opposite side of the film on which the color material layer was applied so as to have a film thickness of 0.1 μm to form a backing layer. Using the obtained heat-sensitive transfer recording medium, blocking, sticking prevention and hot roll contact tests were conducted. The results are shown in Table 1.

(Blocking test) A thermal transfer recording medium was wound around a core having an outer diameter of 17 mm with a tension of 5 g per 1 mm width, placed in an atmosphere of 55 ° C. for 3 days, and then unwound while blocking to transfer the color material layer to the backing layer. Was observed.

(Sticking prevention test) The thermal transfer recording medium was recorded using a thermal head having an element density of 8 lines / mm under the condition that the applied power per heating element was 0.7 W and the applied time was 2.3 ms. The preventive effect was observed.

(Heat Roll Contact Test) A surface provided with a backing layer for leveling the color material layer of the thermal transfer recording medium was brought into contact with a chrome-plated roll at 120 ° C. The state at this time was observed.

 ─────────────────────────────────────────────────── ─── Continuation of front page (56) References JP-A-60-225777 (JP, A) JP-A-60-137690 (JP, A)

Claims (1)

[Claims] 1. A heat-sensitive transfer recording medium having at least one coloring material layer containing a heat-fusible substance on a support, wherein at least the following silicone-modified urethane resin is provided on the support opposite to the coloring material layer. A thermal transfer recording medium having a layer containing one kind. Silicon modified urethane resin: at least 1 in the structural unit
A copolymer of polyurethane and silicone resin obtained from a prepolymer having a certain cyclic structure and diisocyanate.