JP3064744B2 - Thermal recording material - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat-sensitive recording material,
More specifically, the present invention relates to a heat-sensitive recording material useful for a wax-type thermal transfer system and a sublimation-type thermal transfer system.

[0002]

2. Description of the Related Art Conventionally, a heat-sensitive recording layer is formed by carrying a dye or pigment on one surface of a base sheet such as a polyester film with a binder resin, and heating the ink from the back surface in a pattern to transfer the ink to the transfer material. A sublimation-type thermal transfer method is known in which a heat sublimable dye is used as the above-mentioned dye, and only the dye is sublimated and heat-transferred to a material to be transferred.

In each of these methods, thermal energy is applied from the back surface of the base sheet, so that the back surface of the base sheet of the heat-sensitive transfer material to be used has sufficient slipperiness, peelability, and non-adhesion. It is required that the thermal head does not stick to the back surface (sticking development). Therefore, in the related art, a layer made of a silicone resin, a melamine resin, a phenol resin, a polyimide resin, an epoxy resin, a modified cellulose resin, or a mixture thereof is formed on the back surface of the base sheet of the heat-sensitive recording material. (See JP-A-58-13359).

[0004]

[Problems to be solved by the invention]
Since most of these resins are thermosetting resins using various curing agents, there is a problem that a heating step for curing is required at the time of forming the back layer of the thermosensitive recording material, which is complicated. Furthermore,
Although the formed back layer has a high melting point, the film itself is brittle and has poor adhesiveness, so it peels off at the time of printing and remains as a residue on the thermal head, causing a problem in printing.

On the other hand, isocyanate or the like is added to a thermoplastic resin such as an acrylic resin, a polyurethane resin, a polyester resin, and a polybutadiene resin, and these resins are cured to form a back layer, and further, the slipperiness of the thermal head is improved. It has been proposed to add a lubricant or the like to the back layer in order to provide the back layer (see JP-A-59-225994).

In this publication, curing with isocyanate proceeds at room temperature. However, in practice, there is a problem of pot life (pot life) or poor curing due to the reaction of water or other impurities with isocyanate. Problem easily occurs. In addition, the lubricant added for imparting lubricity, when used for a long time, bleeds out the lubricant on the surface of the back layer or becomes a head residue at the time of printing, which hinders printing. There is a problem.

The inventor of the present invention has proposed that the use of a silicone copolymer resin for the formation of the back layer instead of the above-mentioned resin allows the heat-sensitive recording material to have heat resistance, slipperiness, non-adhesion, etc. (Japanese Patent Application Laid-Open Nos. 61-227087 and 62).
-202786).

Accordingly, it is an object of the present invention to provide a heat-sensitive recording material capable of forming a back layer having excellent performance by simplifying the process of forming the back layer and taking the prior art one step further. is there.

[0009]

The above object is achieved by the present invention described below. That is, the present invention provides a base sheet,
In a thermosensitive recording material comprising a heat-sensitive recording layer provided on one surface of the base sheet and a back layer provided on the other surface of the base sheet, the back layer has a polysiloxane compound having an organic functional group. And a reaction product of a silane coupling agent having an organic functional group and an organic polyisocyanate, comprising a resin having at least one free isocyanate group.

[0010]

The back layer of the thermosensitive recording material is formed from a reaction product of a polysiloxane compound having an organic functional group, a silane coupling agent having an organic functional group, and an organic polyisocyanate, whereby the back layer is hydrolyzed. By having a reactive silyl group and a free isocyanate group, crosslinking is performed by moisture or moisture in the air, so that one-pack curing of the coating film becomes possible and the process of forming the back layer can be simplified. Furthermore, due to the presence of the free isocyanate group and the hydrolyzable silyl group, the adhesion of the back layer to the base sheet is improved,
A heat-sensitive recording material having excellent performance is provided.

[0011]

Preferred examples of the polysiloxane compound having an organic functional group constituting the film forming component of the back layer of the heat-sensitive recording material of the present invention include the following compounds.

(1) Amino-modified polysiloxane compound

[0013]

[0014]

[0015]

[0016]

[0017]

(2) Epoxy-modified polysiloxane compound

[0019]

[0020]

[0021]

[0022]

[0023]

The above epoxy compound can be used by reacting it with a polyol, polyamide, polycarboxylic acid or the like so as to have terminal active hydrogen.

(3) Alcohol-modified polysiloxane compound

[0026]

[0027]

[0028]

[0029]

[0030]

[0031]

(4) Mercapto-modified polysiloxane compound

[0033]

[0034]

[0035]

(5) Carboxyl-modified polysiloxane compound

[0037]

[0038]

[0039]

The polysiloxane compounds having an organic functional group listed above are examples of preferred compounds used in the present invention, and the present invention is not limited to these examples. Therefore, not only the above-listed compounds but also other compounds that are currently commercially available and easily available from the market can be used in the present invention.

Examples of the silane coupling agent having at least a reactive functional group used in the present invention include the following compounds. (1) A silane coupling agent having at least one free isocyanate group.

[0042]

(R ¹ is a lower alkyl group, R ² is a lower alkyl group or a lower alkoxy group, X is a divalent organic group, and preferably a C ₀ -C ₅₀ aliphatic, aromatic or aliphatic aromatic group. And these groups may have various atoms or atomic groups such as O, N or S as a linking group therein, and m = 0 to 3; Preferred specific examples of the silane coupling agent having a free isocyanate group are as follows.

[0044]

(2) A silane coupling agent having a reactive functional group other than a free isocyanate group.

(Y is, for example, an amino group, an epoxy group,
Groups which are capable of reacting with an isocyanate group such as a hydroxyl group and a thiol group, particularly preferably an amino group, a thiol group and a hydroxyl group. R ¹ , R ² , X, m and n are as defined above. Preferred specific examples of the silane coupling agent having the reactive functional group are as follows.

[0047]

The silane coupling agents listed above are examples of preferred compounds used in the present invention,
The present invention is not limited to these examples. Therefore, not only the above-listed compounds but also other compounds that are currently commercially available and easily available from the market can be used in the present invention.

As the organic polyisocyanate to be reacted with the polysiloxane compound and the silane coupling agent used in the present invention, any of conventionally known organic polyisocyanates can be used. 2,4-diisocyanate 4-methoxy-1,3-phenylene diisocyanate 4-isopropyl-1,3-phenylene diisocyanate 4-chloro-1,3-phenylene diisocyanate 4-butoxy-1,3-phenylene diisocyanate 2,4-diisocyanate -Diphenyl ether methylene diisocyanate 4,4-methylene bis (phenyl isocyanate)

1,5-naphthalenediisocyanate benzine diisocyanate o-nitrobenzidine diisocyanate 4,4-diisocyanate dibenzyl 1,4-tetramethylene diisocyanate 1,6-tetramethylene diisocyanate 1,10-decamethylene diisocyanate 1,4-cyclohexyl Silylene diisocyanate Xylylene diisocyanate 4,4-methylenebis (cyclohexyl isocyanate) 1,5-tetrahydronaphthalenediisocyanate and the like.

Further, adducts of these organic polyisocyanates with other compounds, for example, those having the following structural formulas, are not limited thereto.

[0052]

[0053]

[0054]

[0055]

[0056]

[0057] Urethane prepolymers obtained by reacting these organic polyisocyanates with low molecular weight polyols or polyamines so as to be terminal isocyanates can also be used in the present invention.

The reaction product used in the formation of the back layer in the present invention comprises 1 to 3 mol of a polysiloxane compound having an organic functional group and 1 to 3 mol of a silane coupling agent having an organic functional group as described above. 1 to 2 moles of an organic polyisocyanate as described above, the organic functional group and the isocyanate group in a functional group ratio in which one or more isocyanate groups are excessive in one molecule, under no solvent or under an organic solvent, About 0-150 ° C. in the presence or absence of a normal urethane catalyst,
Preferably, it can be easily obtained by reacting at a temperature of 20 to 80 ° C. for about 10 to 4 hours.

In the present invention, the above-mentioned reaction product used for forming the back layer can be used alone. However, in order to improve coating suitability to a base sheet or the like, film forming property, etc., a conventionally known reaction product is used. Various resins can be mixed and used. As these various resins, those capable of chemically reacting with the free isocyanate of the above reaction product are preferable, but those having no reactivity can also be used in the present invention.

Examples of these resins include acrylic resin, polyurethane resin, polyester resin, polybutanediene resin, silicone resin, melamine resin, phenol resin, polyvinyl chloride resin, cellulose resin, epoxy resin, polyvinyl butyral resin, alkyd resin, Modified cellulose resin, fluorine resin, polyamide resin and the like can be used. In addition, resins obtained by modifying various resins with silicone or fluorine can also be used. When these various resins are used in combination, the amount used is 0.1% by weight to 100% by weight based on the solid content of the above reaction product.

The back layer formed by the above-mentioned coating composition is cured by causing the hydrolyzable silyl groups in the reaction product to undergo a crosslinking reaction by being brought into contact with moisture, water or steam in the air. Since free isocyanate reacts and cures, no special heating device or heat treatment for curing is required.

In the present invention, in order to promote the silanol condensation, it is preferable to add a catalyst to the back layer coating. Such catalysts generally include alkyl titanates,
Preference is given to carboxylates such as tin octylate, dibutyltin dilaurate, amino salts such as dibutylamine-2-ethylhexoate, and other acidic and basic catalysts.

Some free isocyanate groups and silyl groups interact with the surface of the base sheet to improve the adhesiveness of the back layer, and the polysiloxane portion in the reaction product changes the surface of the back layer. According to the present invention, it is possible to provide a heat-sensitive recording material having excellent properties such as heat resistance, slipperiness, and less generation of head slag.

[0064]

EXAMPLES Next, the present invention will be described more specifically with reference to Reference Examples, Examples and Comparative Examples. In the following, "parts" and "%" are based on weight unless otherwise specified.

Reference Example 1 Adduct of hexamethylene diisocyanate and water (Duranate 24A-100, manufactured by Asahi Kasei, NCO% 23.5
%) 150 parts of ethyl acetate and 100 parts of ethyl acetate were thoroughly stirred at 80 ° C., and 12 parts of polydimethylsiloxane (molecular weight: 2,200) having a terminal hydroxyl group having the above-mentioned structure was gradually added dropwise thereto and reacted for 4 hours. I let it. Thereafter, the mixture was cooled to 40 ° C., and 56 parts of 3-aminopropyltriethoxysilane was gradually added dropwise thereto with sufficient stirring to cause a reaction, thereby obtaining a reaction product (1).

According to the infrared absorption spectrum of the obtained reaction product (1), absorption due to a free isocyanate group was recognized at 2,270 cm ^-1 , and a -SiO- group was detected at 1,090 cm ^-1. Based absorption band. Further, when the free isocyanate groups of the reaction product (1) were quantified, the theoretical value was 11.1%, whereas the actually measured value was 10.3% (as pure content). Finally, ethyl acetate was added to obtain a resin solution (A) having a solid content of 50%.

Reference Example 2

Adduct of 1 mol of trimethylolpropane and 3 mol of toluene-2,4-diisocyanate (Coronate L, manufactured by Nippon Polyurethane, NCO% = 13.0)
%, Solid content: 75%), while thoroughly stirring 200 parts of ethyl acetate and 100 parts of ethyl acetate at 80 ° C., into which polydimethylsiloxane having a hydroxyl group at both ends having the above structure (molecular weight: 3,
200) 12 parts were gradually dropped and reacted. Then 4
The mixture was cooled to 0 ° C., and with good stirring, 62 parts of N-ethyl-γ-aminopropyltriethoxysilane was gradually dropped therein to react to obtain a reaction product (2).

According to the infrared absorption spectrum of the obtained reaction product (2), absorption due to a free isocyanate group was recognized at 2,270 cm ⁻¹ , and a —SiO— group was detected at 1,090 cm ^−1. Based absorption band. In addition, when the free isocyanate groups of this reaction product (2) were quantified, the theoretical value was 6.9%, whereas the actually measured value was 5.1% (as pure content). Finally, ethyl acetate was added to obtain a resin solution (B) having a solid content of 50%.

Reference Example 3

Trimer of hexamethylene diisocyanate (Coronate EH, manufactured by Nippon Polyurethane, NCO% = 2
(1.3%) 150 parts of ethyl acetate and 100 parts of ethyl acetate were stirred well at 80 ° C., and 10 parts of polydimethylsiloxane (molecular weight 2,200) having the structure of Reference Example 1 was gradually dropped thereinto to carry out a reaction. I let it.

Then, while stirring well at 50 ° C., 7 parts of polydimethylsiloxane having the above structure and having amino groups at both ends (molecular weight: 1,800) are gradually dropped, and 72 parts of γ-mercaptopropyltrimethoxysilane are gradually added. To give a reaction product (3).

According to the infrared absorption spectrum of the obtained reaction product (3), absorption due to a free isocyanate group was recognized at 2,270 cm ⁻¹ , and a —SiO— group was detected at 1,090 cm ^−1. Based absorption band. Further, when the free isocyanate groups of this reaction product (2) were quantified, the theoretical value was 6.6%, whereas the actually measured value was 5.7% (as pure content). Finally, ethyl acetate was added to obtain a resin solution (C) having a solid content of 50%.

Example 1 100 parts of the resin solution (A) of Reference Example 1, 300 parts of methyl ethyl ketone, 0.5 part of water and 0.01 part of tin octylate were blended and stirred well to form a back layer of a heat-sensitive recording material. Of the present invention was obtained.

Example 2 100 parts of the resin solution (A) of Reference Example 1, 20 parts of a nitrocellulose resin (solid content 20%, manufactured by Daicel Chemical Industries, Ltd.), 312 parts of methyl ethyl ketone, 0.5 part of water, and 0.1 part of tin octylate. 01 parts was mixed and stirred well to obtain a coating composition of the present invention for forming a back layer of a heat-sensitive recording material.

Example 3 100 parts of the resin solution (B) of Reference Example 2, 300 parts of methyl ethyl ketone, 0.5 part of water and 0.01 part of tin octylate were blended and stirred well to form a back layer of the heat-sensitive recording material. Of the present invention was obtained.

Example 4 100 parts of the resin solution (B) of Reference Example 2, 30 parts of a silicone-polyurethane resin (solid content: 20%, manufactured by Dainichi Seika Kogyo (Dialomer)), 318 parts of methyl ethyl ketone, 0.5 part of water And 0.01 part of tin octylate were blended and stirred well to obtain a coating composition of the present invention for forming a back layer of a heat-sensitive recording material.

Example 5 100 parts of the resin solution (C) of Reference Example 3, 300 parts of methyl ethyl ketone, 0.5 part of water and 0.01 part of tin octylate were blended and stirred well to form a back layer of the heat-sensitive recording material. Of the present invention was obtained.

Example 6 100 parts of the resin solution (C) of Reference Example 3, 60 parts of polyvinyl butyral resin (solid content: 20%, manufactured by Sekisui Chemical Co., Ltd.), 336 parts of methyl ethyl ketone, 0.5 part of water and 0 parts of tin octylate 0.011 part was mixed and stirred well to obtain a coating composition of the present invention for forming a back layer of a heat-sensitive recording material.

COMPARATIVE EXAMPLE 1 150 parts of polybutylene adipate (molecular weight: 2,000) and 15 parts of 1,3-butanediol were dissolved in 200 parts of methyl ethyl ketone and 50 parts of toluene. 6 parts in methyl ethyl ketone
A solution in which 2 parts of water-added MDI was dissolved was gradually added dropwise, and after completion of the addition, the mixture was reacted at 80 ° C. for 6 hours. The solution had a solids content of 40% and a viscosity of 24,000 cps (20 ° C.). Further, this solution was adjusted to a solid content concentration of 12.5% with methyl ethyl ketone to obtain a coating composition for a comparative test.

COMPARATIVE EXAMPLE 2 100 parts of the same resin solution as in Comparative Example 1, 3 parts of Teflon powder (Daikin Industries), 2 parts of polyethylene wax and 255 parts of methyl ethyl ketone / toluene (= 1/1) were blended to form a liquid mixture. . Isocyanate (solid content: 75%, manufactured by Nippon Polyurethane) was added to the above compounding liquid in a resin liquid: isocyanate = 24: 3 (weight ratio) to obtain a coating composition for a comparative test.

Comparative Example 3 100 parts of a silicone resin (KS-841 manufactured by Shin-Etsu Chemical Co., Ltd.) and 1 part of a catalyst (PL-7) were dissolved in 1,000 parts of toluene, and a silicone resin coating composition for a comparative test was prepared. did.

Evaluation Each of the coating compositions prepared in Examples 1 to 6 and Comparative Examples 1 to 3 was gravure-printed onto the surface of a 6 μm-thick polyethylene terephthalate film (manufactured by Toray).
After coating so as to have a thickness of 0.3 μm after drying, the solvent was dried in a dryer to form a heat-resistant lubricating back layer for a comparative test on the surface of the substrate.

Next, the ink composition having the following composition was heated to 100 ° C. and applied by a roll coating method using a hot melt on the surface of the substrate film opposite to the back layer formed as described above. The transfer ink layer was formed by coating so as to have a thickness of 5 μm to obtain a thermal transfer material using the coating compositions of Examples 1 to 6 and Comparative Examples 1 to 3.

Ink composition paraffin wax 10 parts Carnauba wax 10 parts Polybutene (Nippon Oil) 1 part Carbon black 2 parts

Using each of the samples of the heat-sensitive recording material obtained as described above, printing was performed with a thin-film thermal head under the conditions of a printing energy of 1 mJ / dot (4 × 10 ⁻⁴ cm ² ). At this time, the sticking property, the head stain property, the adhesive property and the static friction coefficient were observed and measured for evaluation. These physical property tests were performed after leaving each of the above heat-sensitive recording materials at room temperature (23 ° C., 46% humidity) for 3 days. The results are shown in Table 1 below.

Here, the sticking property is visually evaluated in five stages by the detachability of the heat-sensitive recording material from the thermal head at the time of pressing operation between the thermal head and the heat-sensitive recording material when subjected to the mounting test of the heat-sensitive recording. evaluated. In addition, the thing with the best detachability was set to 5.

For the dirt on the thermal head, the state of dirt on the thermal head when subjected to a thermal recording mounting test was observed. The adhesion test was evaluated by performing a cellophane tape peeling test on the backing layer. The coefficient of static friction was obtained by evaluating the coefficient of static friction of the heat-resistant lubricating layer with a surface property tester (manufactured by Shinto Kagaku).

[0089]

[Table 1]

[0090]

As is clear from the above Table 1, according to the present invention, a heat-sensitive recording material having excellent performance is provided because the back layer has a low coefficient of friction, has low tackiness and little contamination of the head.
Further, since the back layer of the heat-sensitive recording material has a hydrolyzable silyl group and free isocyanate, the back layer is cross-linked by moisture or moisture in the air, and can be cured by one component.
The step of forming the back layer can be significantly simplified.

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int. Cl. ⁷ , DB name) B41M 5/38-5/40

Claims (3)

(57) [Claims] 1. A heat-sensitive recording material comprising a base sheet, a heat-sensitive recording layer provided on one side of the base sheet, and a back layer provided on the other side of the base sheet. The back layer is
A thermosensitive recording, which is a reaction product of a polysiloxane compound having an organic functional group, a silane coupling agent having an organic functional group, and an organic polyisocyanate, comprising a resin having at least one free isocyanate group. material. 2. The heat-sensitive recording material according to claim 1, wherein the back layer contains another binder resin. 3. The heat-sensitive recording material according to claim 1, wherein water is used as a curing agent for the back layer.