JPH0338385A - Thermal transfer recording medium - Google Patents

Abstract

PURPOSE:To form a high-grade printing image having no voids and excellent in printing sharpness even to a transfer medium low in surface smoothness by providing a transfer layer containing hindered phenols along with a colorant and a thermoplastic resin on a support. CONSTITUTION:A thermal transfer recording medium is formed by providing a transfer layer containing hindered phenols along with a colorant and a thermoplastic resin on a support. The support desirably has good heat-resistant strength and high dimensional stability and the thickness thereof is pref. set to a range of 2 - 30mum. When the thickness of the support exceeds 30mum, heat conductivity is deteriorated and a lowering of printing quality is brought about according to circumstances. By containing hindered phenols in the transfer layer, the cohesive force of the transfer layer can be properly controlled without generating background staining and dot reproducibility is enhanced and the adhesiveness or fixability of the transfer layer to a transfer medium are enhanced. Hindered phenols are hindered phenol type compounds being alkyl phenols each having a substituent showing steric hindrance action at an o-position.

Description

[Detailed Description of the Invention] [Field of Industrial Application] 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 scumming and has improved dot reproducibility, and is suitable for use in copy paper, bond paper, etc. Also for transfer media with low surface smoothness.

The present invention relates to a thermal transfer recording medium capable of forming a high-quality printed image with good fixing properties, no voids, and excellent print sharpness.

[Prior art and problems to be solved by the invention g] Thermal transfer recording media (so-called ink ribbons) used in thermal printers, which are widely used in many fields such as word processors, facsimiles, and barcode printers, are: For example, Beck smoothness is 1
When smooth paper of about 00 to 200 seconds is used as the transfer medium,
A clear printed image can be formed.

However, in conventional thermal transfer recording media that have a transfer layer (so-called ink layer) made of wax and coloring material, the surface of the transfer medium has a Bekk smoothness of 2 to 2, such as copy paper or bond paper. If it is about 20 seconds and is a low smooth paper with many irregularities on the surface, the contact area between the thermal transfer recording medium and the transferred medium will be small, and the transfer layer will form a good bridge structure on the paper surface. There are problems in that printing quality deteriorates due to the occurrence of voids that are thought to be caused by the inability to do so, and background smearing due to trailing and the like.

Therefore, in order to solve this problem, attempts have been made to increase the cohesive force of the transfer layer by using a thermoplastic resin instead of wax in the transfer layer, thereby preventing the occurrence of voids and scumming. It is being

However, in thermal transfer recording media having a transfer layer made of thermoplastic resin, although it is possible to suppress the occurrence of voids and scumming, the cohesive force of the transfer layer increases, resulting in poor dot reproducibility and printed images. However, it has not been possible to improve the quality of printed images on low-smooth paper because of problems such as lack of sharpness and poor adhesion to the transfer medium, resulting in poor fixation.

In addition, in order to improve dot reproducibility, attempts have been made to finely disperse wax or immiscible particles in the transfer layer, or there are drawbacks such as background smearing, which leaves the printing quality unsatisfactory. Fixability to transfer media has not yet been achieved.

The present invention has been made based on the above circumstances.

The purpose of the present invention is to eliminate background smearing, improve dot reproducibility, and provide good fixing properties even on transfer media with low surface smoothness, without voids, and with excellent print sharpness. An object of the present invention is to provide a thermal transfer recording medium that can form high-quality printed images.

[Means for Solving the Problems] In order to solve the above problems, as a result of intensive studies by the present inventors, a specific transfer layer containing a specific substance together with a coloring material and a thermoplastic resin on a support was developed. Thermal transfer recording media with this technology do not cause background smudges and have improved dot reproducibility, and can be used even on transfer media with low surface smoothness.
The present invention was achieved by discovering that it is possible to form a high-quality printed image with good fixing properties, no voids, and excellent print sharpness.

The structure of the present invention is a thermal transfer recording medium characterized by having a transfer layer containing a hindered phenol in addition to a coloring material and a thermoplastic resin on a support.

The following is a description of the thermal transfer recording medium of the present invention.

The support, transfer layer, etc. will be explained in detail.

-Support- It is desirable that the support in the thermal transfer recording medium of the present invention has good heat resistance strength and high dimensional stability.

The materials include, for example, papers such as plain paper, capacitor paper, laminated paper, and coated paper; resin films such as polyethylene, polyethylene terephthalate, polystyrene, polypropylene, and polyimide; composites of paper and resin films, and aluminum foil. All metal sheets such as the above are preferably used.

The thickness of the support is usually 30 μm or less, preferably 2 to 2 μm.
It is within the range of 30gm. If the thickness of the support exceeds 30 μm, thermal conductivity may deteriorate, leading to a decrease in printing quality.

In the thermal transfer recording medium of the present invention, the structure on the back side of the support is arbitrary, and for example, a backing layer such as an anti-sticking layer may be provided.

One Transfer Layer In the thermal transfer recording medium of the present invention, a transfer layer is laminated on the support directly or via a suitable intermediate layer.

One of the important points in the present invention is that the transfer layer contains hindered phenols together with the coloring material and the thermoplastic resin.

By containing the hindered phenols in the transfer layer, in the thermal transfer recording medium of the present invention, the cohesive force of the transfer layer can be appropriately controlled without causing scumming, and dot reproducibility is improved. At the same time, the adhesion and fixing properties of the transfer layer to the transfer medium are improved.

The hindered phenols are hindered phenol compounds, which are alkylphenols having a substituent at the ○-position that exhibits steric hindrance.

Specifically, the following formula (I).

[However, in the formula CI), R' represents a tertiary butyl group,
RQ represents a hydrogen atom, a methyl group, or a tertiary-butyl group, X represents a right-handed radical, and r represents 0 or 2.] Or the compound represented by the following formula (■); (However, (n) In the formula, 1 and R2 are as above (the sentence represents an integer from 1 to 3) and -C11□CH
Represents either 2CNH-, Z is -(CHz)+-
(symbol has the same meaning as above) or -C1hCH
*0CHt-, A is a carbon atom, sulfur atom R4 is a hydrogen atom or an ethoxy group, k is 0 or l, and n is 2 or 4.

m represents O or 2) Compounds represented by the following can be mentioned.

Specifically, the hindered phenols include, for example, triethylene glycol-bis[3-(3-t-butyl-5-methyl-4-hydroxyphenyl)propionate], 1,6-hexanethiol bis[ 3-(3
, 5-di-t-butyl-4-hydroxyphenyl)propionate], 2,4-bis(n-octylthio)
-6-(4-hydroxy-3,5-di-t-butylanilino)-1,3,5-triazine, pentaerythrityl-tetrakis[3-(co,5-di-t-butyl-4-hydroxyphenyl)propionate 1.2.2-thio-
Diethylenebis(3-(3゜5-di-t-butyl-4-
hydroxyphenyl)propionate], octadecyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate, 2,2-thiobis(4-methyl-6-t-butylphenol), N,N'- xamethylenebis(3,5-di-t-butyl-4-hydroxy-hydrocinnamamide), 3,5-di-t-butyl-4
- hydroxypenzyl phosphonate diethyl ester, 1,3. S-trimethyl-2,4,6-tris(3,5-di-t-butyl-4-hydroxypencyl)benzene, 2,6-di-t-butyl-p-cresol, 2,4.6-trit -butylphenol, 4-
Hydroxy-methyl-2,6-di-t-butylphenol, 2.5-di-t-butyl-hydroquinone, butylhydroxyanisole, 2,2'-methylene-bis-
(4-methyl-8-t-butylphenol).

2.2'-methylene-bis-(4-ethyl-6-t-butylphenol), 4.4'-thucylidene-bis(3
-methyl-6-t-butylphenol), 4,4'-methylene-bis-(2,6-di-t-butylphenol)
, 2,6-bis(2'-hydroxy-3'-t-butyl-5'-methylbenzyl)4-methyl-phenol, 1
,1. :l-tris(2-methyl-4-hydroxy-
5-t-butylphenyl)butane, 1,3.5-tris-methyl-2,4,6-t-lis(3,5-di-t-
butyl-4-hydroxy-pencyl)benzene, tetrakis[methylene-3(3,5-di-t-butyl-4-hydroxyphenyl)propionate comethane, tris(
3,5-di-t-butyl-4-hydroxyphenyl)isocyanurate, tris[β-(co,5-di-t-butyl-4-hydroxyphenyl)propionyl-oxyethyl]isocyanate, l, 3゜5-tris- Methyl-
2,4,6-)-Lis(3,5-sheet-t-butyl-4-
hydroxybenzyl)benzene, 4.4'-thiobis(3-methyl-6-t-butylphenol), 2,
Examples include 2'-thiobis(4-methyl-6-t-butylphenol) and 4.4'thiobis(2-methyl-6-t-butylphenol).

In any case, the melting point of the hindered phenols that can be suitably used in the present invention is 50 to 200°C.
, preferably at 50 to 120°C, and the molecular weight is 150
~z,ooo, preferably 500-I,000.

Therefore, among the various hindered phenols mentioned above, preferred are 2.6-sheet t-butyl-p-cresol, butylhydroxyanisole, and 1.6-hexanethiolupis[3-( 3,5-sheet-t-butyl-4-
hydroxyphenyl>propionate], octadecyl-3-(:1,5-di-t-butyl-4-hydroxyphenyl)propionate, 2,4-bis-(n-octylthio)-6-(4-hydroxy-3, 5-di-t-butylanilino)-1,3,5-triazine, particularly preferred are octadecyl-3-(3,5-se-t-phthyl-4-hydroxyphenyl)propionate, 1.
6-hexanethiolubis[3-(3,5-sheet t-
butyl-4-hydroxyphenyl)propionate],
2.4-bis-(n-octylthio)-6-(4-hydroxy-3,5-di-t-butylanilino) -1,3
,5-)-riazine.

The hindered phenols may be used alone or in combination of two or more.

The content of the hindered phenols in the transfer layer is usually 1 to 50% by weight, preferably 1 to 20% by weight.

In this MIJJ, the thermoplastic resin contained in the transfer layer together with the hindered phenols includes at least (1) imparting film-forming properties to the transfer layer, so that even a transfer medium with low surface smoothness can have a bridge structure; (1) It is required to have tackiness or adhesion when heated to help the adhesion between the transfer layer and the medium to be transferred.

The glass transition temperature (Tg) of the thermoplastic resin to satisfy such conditions is usually -20 to 70°C, preferably -10 to 60°C.

Specifically, the thermoplastic resin includes, for example, polyamide resin, polyester resin, polyurethane resin, polyolefin resin, (meth)acrylic resin, (
Resins such as meth)acrylic acid copolymer resin, A styrene-(meth)acrylic acid copolymer resin, vinyl chloride resin, cellulose resin, rosin resin, ionomer resin and petroleum resin: natural rubber, styrene butadiene rubber.

Elastomers such as isoprene rubber and chloroprene rubber; styrene-butadiene rock polymers (e.g.
SBS, SIS, 5EIS, etc.) and their hydrogenated compounds;
Rosin derivatives such as ester gum, rosin maleic resin, rosin phenol resin and hydrogenated rosin; ethylene-
Ethylene copolymers such as vinyl acetate copolymers and ethylene-ethyl acrylate copolymers; polymeric compounds such as phenolic resins, terpene resins, cyclopentadiene resins, and aromatic hydrocarbon resins. I can do it.

Among these, preferred are polyester thread resin, polyurethane resin, (meth)acrylic resin and its copolymer resin, and ethylene copolymer.

The thermoplastic resins may be used alone or in combination of two or more.

In any case, the melt index (MI) of the thermoplastic resin that can be suitably used in the present invention is:
Usually, it is O-1,5000, preferably O-500. Further, the thermoplastic resin has a softening point of 60 to 15
The content of the thermoplastic resin in the transfer layer, which is preferably in the range of 0°C, is usually 4 to 1.
-99% by weight, preferably 5-80% by weight.

The transfer layer contains one coloring material together with the hindered phenol and the thermoplastic resin.

Examples of the coloring material include pigments such as inorganic pigments and organic pigments, and dyes.

The inorganic pigments include 1, titanium dioxide, carbon black, zinc oxide, Prussian blue, cadmium sulfide,
These include iron oxides and chromates of lead, zinc, barium and calcium.

Examples of the organic pigments include azo, thioindigo, anthraquinone, anthanthrone, and triphenedioxazine pigments, vat dye pigments, phthalocyanine pigments, such as copper phthalocyanine and its derivatives, and quinacridone pigments.

Examples of the organic dye include acid dyes, direct dyes, disperse dyes, oil-soluble dyes, and metal-containing oil-soluble dyes.

Among these various coloring materials, carbon black is particularly preferred.

The content of the coloring material in the transfer layer is usually in the range of 5 to 35% by weight, preferably in the range of 10 to 30% by weight.

The transfer layer may contain various additives in addition to the hindered phenols, the thermoplastic resin, and the coloring material in order to adjust the melting point or softening temperature, cohesive force, adhesive force, etc. of the entire transfer layer. good.

Examples of such additives include polyester waxes, amide waxes, and oxidized waxes.

Examples include higher fatty acids, higher fatty acid esters, butyral resins, sucrose esters, polyoxyethylene chain-containing compounds, inorganic or organic fine particles (metal powder, silica gel, etc.), oils (linseed oil, mineral oil, etc.).

The transfer layer can be coated on the support via a suitable intermediate layer or directly by employing a coating method such as a water-based coating method or a coating method using an organic solvent.

The layer thickness of this transfer layer is usually within the range of 0.2 to 81 Lm, preferably within the range of 0.2 to 5.0 pm.

-Others- In the present invention, it is preferable that the transfer layer is provided on the support via a release layer which will be described in detail below.

By providing a release layer, the releasability of the transfer layer can be further improved, and the acid content forming the transfer layer can be prevented from being inadvertently spread onto the support. .

It is necessary that the peeling layer melts when heated and causes a single failure.

The release layer exhibiting such properties is usually one.

Contains heat-melting substances.

Examples of the heat-melting substances include vegetable waxes such as carnauba wax, wood wax, auriculie wax, and Nispar wax; animal waxes such as beeswax, insect wax, shellac wax, and spermaceti wax; paraffin wax, microcrystalline wax, polyethylene wax, and esters. Mention may be made of waxes such as petroleum waxes such as waxes and acid waxes; and mineral waxes such as montan wax, osichelite and ceresin; in addition to these waxes, palmitic acid, stearic acid, margaric acid and behenyl Higher fatty acids such as acids; higher alcohols such as palcutyl alcohol, stearyl alcohol, behenyl alcohol, marganyl alcohol, myricyl alcohol, and eicosanol; Examples include higher fatty acid esters such as acetamide, propionic acid amide, palmitic acid amide, stearic acid amide and amide wax, and higher amines such as stearylamine, behenylamine and palmitic acid ester.

These may be used alone or in combination of two or more.

Among these, preferred is a wax whose melting point is within the am range of 50 to 120°C as measured using a Yanagimoto MJP-2 model.

What is the content of the heat-fusible substance in the release layer?

Usually, it is 50% by weight or more, preferably 70 to 9% by weight.

In addition, in order to improve the adhesive strength with the support or the transfer layer, the release layer may contain, for example, ethylene-vinyl acetate copolymer, ethylene-ethyl acrylate copolymer, styrene phtadiene block polymer, etc. It is preferable to contain an appropriate adhesive.

When this adhesive is used, the content in the release layer is usually 1 to 50% by weight, preferably 1 to 30% by weight.

Furthermore, it is preferable that the peelable S layer contains a coloring material together with the thermofusible substance and the adhesive used if desired.

When the release layer contains a coloring material, the print density can be improved.

The coloring material that can be contained in the peeling layer is the same as the coloring material that can be contained in the transfer layer. However, it is desirable that the color of the colorant contained in the release layer is the same as the color of the colorant contained in the transfer layer. If the color differs from the color of the coloring material used, the desired effect of improving print density may not be achieved sufficiently.

The content of the coloring material in the release layer is usually 0 to 4.
0% by weight, preferably 0-30% by weight.

The release layer can be coated directly onto the support by employing a coating method such as a water-based coating method or a coating method using an organic solvent.

The thickness of this release layer is usually in the range of 0.1 to 8 μm, preferably in the range of 0.5 to 5 pm.

The thermal transfer recording medium of the present invention usually includes, on the support,
It can be manufactured by coating the release layer and the transfer layer in this order, and then optionally performing a drying process, a surface smoothing process, etc., and then cutting into a desired shape.

The heat-sensitive transfer recording medium thus obtained can be used, for example, in the form of a typewriter ribbon or a wide tape generally used in line printers.

[Example] Next, Examples and Comparative Examples of the present invention will be shown to further specifically explain the present invention.

(Example 1) A coating solution obtained by hot melt dispersing the following release layer composition on a polyethylene terephthalate film having a thickness of 3.54 m was applied to a film thickness of 2 gm by a gravure detection method.

Company JL! Paraffin wax (melting point 68°C) 80% by weight ethylene-vinyl acetate copolymer 5% by weight (vinyl acetate content 28%) Carbon black 15% by weight
A coating solution obtained by dispersing the following transfer layer composition in a ball mill for several hours was coated on the peeling layer II by a solvent coating method using a wire bar to a dry film thickness of 24 m to form a transfer layer. A thermal transfer recording medium of the present invention was obtained.

1"0 old koji polyester resin...3% by weight [glass transition temperature (Tg) -5°C1 molecular weight 40.0001 ethylene-vinyl acetate copolymer...5% by weight (acetic acid Vinyl content: 33%) Octadecyl-3-(3,5-sheet-t-butyl-4-troxyphenyl) Propionate: 1% by weight Carbon black: 2% by weight Phenol resin・
......2% by weight (softening point 65°C) Methyl ethyl ketone...87% by weight The obtained thermal transfer recording medium was transferred to a commercially available printer (24F-1).
Serial head, applied energy; 30 J/A19F
), print on low smooth paper (Beck smoothness 2 seconds) and smooth paper (Beck smoothness 200 seconds), and evaluate print quality, dot reproducibility, background smearing, and fixability. I did it.

The results are shown in Table 1.

In addition, each item was evaluated as follows.

Print quality: Visually evaluated.

Dot reproducibility: Dot reproducibility in checkered patterns and 1-dot vertical striped patterns! I observed and evaluated Q.

Background smudge: Stain on the paper surface after printing was visually evaluated.

Fixability: The printed surface was peeled off using an adhesive tape ["Bost It Cheeve"; manufactured by Takumyo 3M Co., Ltd.], and the amount of ink transferred to the adhesive tape side was evaluated.

In Table 1, the meanings of the symbols are as follows.

Edge and I ○...No voids or cast, excellent sharpness.

×・・・・・・There are many voids, Characters are difficult to read stomach.

Upper J Jinhi 1m sex O......1 dot is reproduced.

Δ: Missing dots and connections between dots are seen here and there.

×・・・・・・One dot is not reproduced and some dots are missing. Connections between the keys and dots can be seen.

Mass j1 Rainbow O... There is no ink stain in the non-printed area.

Δ・・・・・・・・・Start of printing, Specific locations such as the rear end Dirt occurs on the surface.

X: The entire surface of the paper is dirty.

"Consistency 0...The ink on the printed area does not come off even when the tape is peeled off.

Δ・・・・・・Peeling off by peeling off the tape.

×・・・・・・The tape peels off when peeled off.

Part of the printed area Most of the printed area (Example 2) In the above Example 1, the following release layer composition and transfer layer were used in place of the release layer composition and transfer layer part I & material used in the above Example 1. The same procedure as in Example 1 was carried out except that the composition was used.

Note that the transfer portion J& material was dispersed and applied in MEK in the same manner as in Example 1 above.

The results are shown in Table 1.

Company Koji paraffin wax (melting point 68°C> 95% by weight 5E
BS・・・・・・・・・◆・・・ 5% by weight [Shell Chemical @Ii! r ri1z-f'to, /G1657 J ]
iJJ Motion” 1 Butyl methacrylate 15% by weight [Glass transition temperature (Tg) 20°C, molecule f! 360,000] Ethylene-vinyl acetate copolymer...5% by weight (vinyl acetate content 33%) 1.6-hexanethiol bis[3-(3,S-di-t-butyl-4-hydroxy) Phenyl) propionate]...10% by weight Polystyrene resin......50% by weight (R 5R-75, manufactured by Sanyo Chemical Co., Ltd.) Carbon black......20% by weight ( Example 3) In the above Example 1, the following release layer composition and transfer layer assembly R & product were used in place of the release layer composition and transfer layer composition used in the above Example 1. It was carried out in the same manner as in Example 1.

The transfer layer composition was dispersed in MEK and applied in the same manner as in Example 1 above.

The results are shown in Table 1.

Shaun" 0 Kajisho paraffin wax (melting point 68°C) 95% by weight 5E
BS・・・・・・・・・・・・ 5% by weight [Krayton G1657 J manufactured by Shell Chemical ■] Transfer 1 Butyl methacrylate・・・・・・ [Glass transition temperature (Tg) 20° C1 molecular weight 360
．． 000 ] Ethylene-vinyl acetate copolymer... (vinyl acetate content 33%) 2.4-bis-(n-octylthio) 6-(4-hydroxy-3,5-di-t-butylanilino) -1,3 ,5-triazine...
・・・・・・・・・ E-caprolactone・・・・・・・ (Softening point 60°C) ・15% by weight 5% by weight ・10% by weight ・50% by weight Carbon black・・・・・・・・・...20% by weight (Comparative Example 1) In Example 1, the same procedure as in Example 1 was used except that the following transfer layer composition was used in place of the transfer layer composition used in Example 1. A heat-sensitive transfer recording medium was manufactured by laminating a release layer and a transfer layer in this order on a support, and this heat-sensitive transfer recording medium was evaluated.

The transfer layer composition was dispersed in MEK and applied in the same manner as in Example 1 above.

The results are shown in Table 1.

Butyl methacrylate...15% by weight [Glass transition temperature (Tg) 20°C1 molecular weight 360.00
0 coethylene-vinyl acetate copolymer...5% by weight (vinyl acetate content 33%) Polystyrene resin...60% by weight (R 5B-75, manufactured by Sanyo Chemical Co., Ltd.) Carbon black... ...20% by weight (Comparative Example 2) In Example 1, the following transfer layer composition was used in place of the transfer layer composition used in Example 1. In the same manner as above, a heat-sensitive transfer recording medium was produced in which a release layer and a transfer layer were laminated in this order on a support, and this heat-sensitive transfer recording medium was evaluated.

The transfer layer composition was dispersed in MEK and applied in the same manner as in Example 1 above.

The results are shown in Table 1.

1" D [Kokoji Ethylene-vinyl acetate copolymer...20% by weight (vinyl acetate content 33%) Oxidized wax......10% by weight Carbon black... ...20% by weight phenol resin (softening point 65°C)...50% by weight (evaluation) As is clear from Table 1, the thermal transfer recording medium of the present invention can be used not only for smooth paper but also for bond paper. It has high print quality even on transfer media with low surface smoothness such as paper, has excellent dot reproducibility, and forms high-quality printed images with no background smudges and excellent fixation properties. I confirmed that it is possible.

[Effects of the Invention] According to the present invention, (1) Since the transfer layer laminated on the support contains a hindered phenol together with a coloring material and a thermoplastic resin, it does not cause background smearing and does not reproduce dots. (2) Even on transfer media with low surface smoothness, such as bond paper, it has good fixing properties and no voids. Furthermore, it is possible to provide a high-performance thermal transfer recording medium that has the advantage of being able to form a high-quality printed image with excellent print sharpness.

Claims (1)

[Claims] (1) A thermal transfer recording medium characterized by having a transfer layer containing a hindered phenol along with a coloring material and a thermoplastic resin on a support.