JPS6221595A - Transfer medium for thermal recording - Google Patents

Abstract

PURPOSE:To obtain the titled medium having excellent clearness of print, transfer properties or the like, by incorporating a resin having a number average molecular weight of not more than 30,000, an ethylene-vinyl acetate copolymer and a pigment or a dye into an ink layer, in a transfer medium for thermal recording which has an ink layer on a base. CONSTITUTION:The transfer medium for thermal recording comprises an ink layer on a base, the ink layer comprising a resin having a number average molecular weight of not more than 30000. The resin is not particularly limited, and at least one polyolefin, copolymer thereof or the like is used either singly or in combination. The ink layer further comprises an ethylene-vinyl acetate copolymer which has an average molecular weight of about 1,000-2,00,000. Further, a pigment or a dye is incorporated in the ink layer. the thickness of the ink layer is 0.5-20mum, preferably, about 0.8-10mum. If the thickness is more than 20mum, the problem of low transferring sensitivity or unclear print is generated.

Description

DETAILED DESCRIPTION OF THE INVENTION (1) Background of the Invention Technical Field The present invention relates to a transfer medium for thermal recording.
For more information, please refer to fax, computer printer,
'This invention relates to the improvement of ink layers of thermal recording transfer media for output printers of OA equipment, various recorders, etc.

Prior art and its problems In recent years, with the diversification of information, the development of thermal recording transfer media for use in facsimiles, computer printers, output printers for OA equipment, various recorders, etc. has been actively promoted. .

This type of thermal recording has the advantages of being able to easily obtain colored characters and images using heating means, eliminating the need for a complicated development process, and using relatively compact and simple hardware. .

BACKGROUND ART Conventionally, so-called thermal paper of dye coloring type or metal compound type is known as a commonly used thermal recording medium. However, recently there has been a strong demand for image reliability, and a recording method using a thermal recording transfer medium for obtaining transferred characters and images on so-called plain paper is becoming mainstream.

A transfer medium for thermal recording used in such a recording method is usually formed by depositing an ink layer containing a colorant and a resin on a substrate.

Various reports have been made regarding such media.
Improvements in printing clarity and storage stability (Unexamined Japanese Patent Publication No. 53
-81246, 55-39381, 58-
(No. 199195), improvement regarding wear resistance (Japanese Patent Application Laid-open No. 5
8-201693), print clarity, adhesion to the base material,
There are improvements regarding transferability (Japanese Patent Application Laid-Open No. 59-29196).

However, in practical use, the uniformity of transferred characters and images during continuous use over a long period of time is not yet satisfactory.

+1 The purpose of the present invention is to provide a heat-sensitive material that has excellent uniformity of transferred characters and images during long-term continuous use, and also has excellent print clarity, storage stability, abrasion resistance, and transferability. An object of the present invention is to provide a transfer medium for J-iL.

■ Disclosure of the Invention The first objective is achieved by the present invention described in F.

That is, the present invention provides a thermal recording transfer medium having an ink layer on a substrate, in which the ink layer has a number average molecular weight of 1300.
00 or less resin, an ethylene-vinyl acetate copolymer,
This is a transfer medium for heat-sensitive recording characterized by containing a pigment or a dye.

■Specific structure of the invention Hereinafter, a specific configuration of the present invention will be explained in detail.

The transfer medium for thermal recording of the present invention (hereinafter referred to as transfer medium in !11) has an ink layer on the substrate. -The ink layer contains a resin having a number average molecular weight of 1.30,000 or less, an ethylene-vinyl acetate copolymer, and a pigment or dye.

The resin used in the present invention is not particularly limited, but among them, the resins shown below are preferred.

i) Polyolefins, polyethylene, polypropylene, poly4-methylpentene-1, etc.゛ □ii) Poly'olefin copolymer' For example, ethylene-vinyl acetate co-f[i-S form, ethylene-acrylic acid ester copolymer, ethylene-acrylic acid copolymer, ethylene-propylene copolymer, ethylene -butene-1 copolymer, ethylene-maleic anhydride copolymer, ethylene propylene turbopolymer (EPT), etc.

In this case, the polymerization ratio of the comonomers can be arbitrary.

1ii) Vinyl chloride copolymers, such as vinyl acetate-vinyl chloride copolymers, vinyl chloride-vinylidene chloride copolymers, vinyl chloride-maleic anhydride copolymers, acryl esters or methacrylic esters. Copolymers with vinyl chloride, acrylonitrile-vinyl chloride copolymers, vinyl chloride ether copolymers, ethylene or propylene-vinyl chloride copolymers, ethylene-vinyl acetate copolymers with vinyl chloride graft polymerized, etc.

In this case, the copolymerization ratio can be arbitrary.

iv) Hinylidene chloride/j' copolymer Vinylidene chloride-vinyl chloride copolymer, vinylidene chloride-vinychloride-acrylonitrile 11-m copolymer, vinylidene chloride-butadiene-vinyl halide copolymer, etc.

In this case, the copolymerization ratio can be arbitrary.

■) Polystyrene vi) Styrene copolymer such as styrene-acrylonitrile copolymer (AS resin), styrene-acrylonitrile-butadiene copolymer (ABS resin), styrene-maleic anhydride copolymer (SMA resin), styrene- Acrylic acid ester-acrylamide copolymer, styrene-butadiene copolymer (
SBR), styrene-vinyritine chloride copolymer, styrene-methyl methacrylate copolymer, etc.

In this case, the copolymerization ratio can be arbitrary.

vii) Styrenic polymers such as α-methylstyrene, p-methylstyrene, 2
, 5-dichlorostyrene, α.

β-vinylnaphthalene, α-vinylpyridine, acenaphthene, vinylanthracene, etc., or copolymers thereof, such as copolymers of α-methylstyrene and methacrylic acid ester.

viiiJ Coumaron-Inten resin Coumarone-indene-styrene copolymer.

ix) Terpene resin or picolite For example, terpene resin which is a polymer of limonene obtained from α-pinene, and picolite obtained from β-pinene.

X) Acrylic resins Particularly preferred are those containing the radical 'r' group represented by the F-formula.

Formula RIO CH-C- In the above formula, RIO represents a hydrogen atom or an alkyl group, and R represents a substituted or unsubstituted alkyl group.

In this case, in the above formula, RID is preferably a hydrogen atom or a lower alkyl group having 1 to 4 carbon atoms, particularly a hydrogen atom f or a methyl group. In addition, R20 is
Although it may be a substituted or unsubstituted alkyl group, the number of carbon atoms in the alkyl group is preferably 1 to 8.
Further, when R2[l is a substituted alkyl group, the substituent substituting the alkyl group is preferably a hydroxyl group, a halogen atom, or an amino group (particularly a dialkylamino group).

The r-group represented by the -1- formula may form a copolymer with other repeating r-groups to form various acrylic resins, but usually -I- An acrylic resin is formed by forming a homopolymer or copolymer having one or more of the atomic groups represented by the formula as repeating units.

xi) Polyacrylonitrile xii) Acrylonitrile copolymer, for example, acrylonitrile-vinyl acetate copolymer, acrylonitrile-vinyl chloride copolymer, acrylonitrile-styrene copolymer, acrylonitrile-vinylidene chloride copolymer, acrylonitrile-vinylpyridine copolymer , acrylonitrile-methacrylic acid methino-drite copolymer, acrylonitrile-butadiene copolymer, acrylonitrile-butyl acrylate copolymer, etc.

In this case, the copolymerization ratio can be arbitrary.

xiii) Diacetone acrylamide polymer A diacetone acrylamide polymer obtained by treating acrylonitrile with acetone.

x1v) Polyvinyl acetate xv) Vinyl acetate copolymers, such as copolymers with acrylic esters, vinyl ethyl, ethylene, vinyl chloride, etc.

The copolymerization ratio may be arbitrary.

xvi Polyvinyl ethers such as polyvinyl methyl ether, polyvinylethyl ether, polyvinyl butyl ether, etc.

xvii) Polyamide In this case, polyamides include ordinary homonylons such as nylon 6, nylon 6-6, nylon 6-10, nylon 6-12, nylon 9, nylon 11, nylon 12, and nylon 13, as well as nylon 67. Low 676-1
0, nylon 6/6-6/12, nylon 6/6-6/
It may also be m-coalescence such as No. 11 or modified nylon depending on the case.

xviii) Polyesters, for example, aliphatic dibasic acids such as oxalic acid, succinic acid, maleic acid, adipic acid, sebastenic acid, or aromatic dibasic acids such as isophthalic acid, terephthalic acid, etc., and ethylene. Condensates and co-condensates with glycols such as glycol, tetramethylene glycol and hexamethylene glycol are suitable.

Among these, condensates of aliphatic dibasic acids and glycols and cocondensates of glycols and aliphatic dibasic acids are particularly suitable.

Furthermore, for example, a modified glybutal resin obtained by esterifying and modifying glybutal resin, which is a condensation product of phthalic anhydride and glycerin, with a fatty acid, a natural resin, etc., is also preferably used.

xix) Polyvinyl acetal resin Both polyvinyl formal and polyvinyl acetal resin obtained by acetalizing polyvinyl alcohol are preferably used.

In this case, the degree of acetalization of the polyvinyl acetal resin can be arbitrary.

xx) Polyurethane resin Thermoplastic polyurethane resin with urethane bonds.

Particularly suitable are polyurethane resins obtained by condensation of glycols and diisocyanates, particularly polyurethane resins obtained by condensation of alkylene glycol and alkylene diisocyanate.

xxi) Polyether styrene formalin resin, ring-opening polymer of cyclic acetal, polyethylene oxide and glycol, polypropylene oxide and glycol, propylene oxide-ethylene oxide copolymer, polyphenylene oxide, etc.

xxii) Cellulose derivatives, such as nitrocellulose, acetylcellulose, ethylcellulose, acetylbutylcellulose, and various esters and ethers of cellulose, such as droxyethylcellulose, hydroxypropylcellulose, methylcellulose, ethylhydroxyethylcellulose, and mixtures thereof.

xxiii) polycarbonates such as polydioxydiphenylmethane carbonate,
Various polycarbonates such as dioxydiphenylproban carbonate.

xx punishment) ionomer Na such as methacrylic acid and acrylic acid.

Li, Zn, Mg salts, etc.

xxv) Ketone resins, for example, condensates of cyclic ketones such as cyclohexanone and acetophenone and formaldehyde.

xxvi) Xylene resins, such as m-xylene or a condensate of mesitylene and formalin, or various modified products thereof, such as rosin modification.

)<xvN) Petroleum resins Ch-based, C9-based, C5-Cg copolymer-based, dicyclopentadiene-based, or co-11i combinations or modified products thereof.

In the present invention, the above resins i) to xxvii) may be used in intermediate types or in a blend of two or more types.

The number average molecular h1 of these resins is 30 as described in -
000 or less, particularly preferably 300 to 10,000.

When this number average molecular weight exceeds 30,000, transfer sensitivity
Print uniformity becomes extremely poor.

Ethylene-vinyl acetate copolymer (EVA) is contained in the first ink layer. Ethylene-vinyl acetate copolymer is a thermoplastic resin made by copolymerizing ethylene and vinyl acetate, and its number average molecular weight is 1,000 to 20,000.
It is about 0.

The content of vinyl acetate is approximately 5 to 70 wt%.

Such an ethylene-vinyl acetate copolymer is contained in an amount of 1 to 200 parts by weight, more preferably 3 to 100 parts by weight, per 100 parts by weight of the above-mentioned resin.

If the content is less than 1 part by weight, the present invention will not be effective;
Moreover, if the amount exceeds 200 parts by weight, there will be a problem that the transfer sensitivity will be low.

In addition to these, the ink layer of the present invention further contains a pigment or dye.

Pigments used include azo dyes, anthraquinones,
Indigoid type, soluble dye type, sulfide type, carbonium type, phthalocyanine type, quinone imine type, cyanine type,
There are nitroso-based, nitro-based, stilbene-based, quinoline-based, pyrazolone-based, 1:2 type metal complex salt-based, henzoquinone-based, naphtoki, non-based, etc., but in the present invention, they are mainly contained to obtain color characters and images. It is something that

Therefore, it is preferable to use pigments that have been separated into the colored threads shown below.

(1) Red (magenta) Azo type, dyed with lake, fused polycyclic (anthraquinone, thioindigo, perinone, perylene, quinacridone, isoindolinone) alizarin lake, daylight fluorescence, specifically pigment red 57.57: 1.57:2
(Color index) For example, Br1lliant C
armin 6B, 6B Tourer (large [1 refinement) Symuler Br1lliant Carmi
ne 6B (Dainippon Ink) Sanyo Br1lliant Carmine 6
B, 68N (deuterochrome) Sanyo Fast Re
d F6R (deuterochrome) Sanyo Lithol R
ubin BKN (deuterochrome) Graph
ol Rubin BP (Sand) R
ubin Toner 4B, 4BA (
I CI ) Vulcafor C1aret Y
There are pigments such as (IC[).

(2) Yellow Azo type, dyed with lake, condensed polycyclic (anthraquinone, isoindolinone, quinophthalone, isoindoline, nitroso, metal complex salt, azomethine, daylight fluorescence, specifically pigment yellow 13 (color) Index) For example, Benzidine Yellow 2GR (Dainippon Rukka) Symuier Fast Yellow GRF
(Dainippon Ink) Sanyo Light Fa
st Benzidine Yellow R (deuterochrome) Graphol Yellow GRIIL
(Sun F) Monolite Yellow G
l, (ICI)Vynason Yellow
There are pigments such as ow GRE (I CI ).

(3) Blue (cyan) Azo type, phthalocyanine, lake dyeing, fused polycyclic (anthraquinone), alkali blue, daylight fluorescence, specifically pigment blue 15 (color index) For example, Lionol Blue FG 7351
(Toyo Ink) Lionol Blue FG 739
3G (Toyo Ink) GrapMol Bl
ue 2Gl-5 (Sand) Monast, r
al Fast 1llue IIG
There are pigments such as (I CI ).

(4) Black Aniline black, carbon black The pigment may be inorganic as well as organic.

The average particle size of such pigments is 0.005 to 10 μm.
The thickness is preferably 0.01 to 4 μm.

If the average particle diameter exceeds 10 μm, the uniformity and sharpness of the print will deteriorate, and there will be a disadvantage that the color will be lost when the particle size is 0.005 μm.

Such a pigment is contained in an amount of 1 to 200 parts by weight, more preferably 3 to 70 parts by weight, per 100 parts by weight of the above-mentioned resin.

Instead of using such pigments, it is also possible to use dyes, preferably oil-soluble, as shown below.

The oil-soluble dye is preferably one that can be dissolved in an organic solvent at 20° C. in an amount of 10 g/Q or more. As the organic solvent, one or more of alcohol, aromatic, ester, gamma ton, and cellosolve solvents are selected and used.

The oil-soluble dyes used in the present invention and their solubility are shown below.

Such oil-soluble dyes are contained in an amount of 1 to 120 parts by weight, more preferably 4 to 40 parts by weight, per 100 parts by weight of the above-mentioned resin.

Furthermore, the ink layer contains these dyes or pigments, ethylene-vinyl acetate copolymer, and a number average molecular weight of 30,000 F or more.
In addition to the above resin, if necessary, various waxes, various pigments, various oils, various ceramic particles, various polymers, dispersants, plasticizers, stabilizers, etc. may be added to 100 parts by weight of the resin.
．． Approximately 1 to 10 parts by weight may be added.

The thickness of the ink layer formed from the composition as described above is 0.5 to 20 μm, more preferably 0.8 to 10 μm.
It is said to be on the order of μm. If the thickness exceeds 20 μm, there will be problems such as lower transfer sensitivity and loss of print clarity, and if it is less than 0.5 μm, there will be problems that the print density cannot be maintained at 1-min. arise.

The ink layer having such a thickness can be formed by various known layering methods, such as melt fT- using hot melt, gravure coating, reverse roll coating, roll coating, air knife coating, dirough coating, and spinner coating. A solution method such as the above may be used.

The substrate on which such an ink layer is deposited is polyethylene terephthalate (PET), polyethylene, polycarbonate, nylon, polyamide, polyimide, polyphenylene sulfide, polysulfone, wholly aromatic polyester, polyether ether, polyether sulfate, etc. It is preferred to use resinous materials such as carbon and polyetherimide.

The thickness of such a substrate is not particularly limited, and is usually about 0.8 to 20 .mu.I.

Further, the shape of the base body is not particularly limited, and various shapes are possible. Further, the medium of the present invention may be used for a single color or for multiple colors, and its structure may be one of various known structures.

A top coat layer containing various waxes or the like may be provided on the ink layer of the present invention.

Furthermore, on the back side of the base (the side on which the ink layer is not provided), an A4
A back coat layer containing a surgical metal layer such as, a silicone or fluororesin, a thermosetting resin, a thermosetting resin, etc. may be provided.

■Specific effects of the invention In the thermal recording transfer medium of the present invention, plain paper is placed on the ink layer of the medium, and the ink layer is heated by the thermal head that contacts the back surface of the substrate of the medium and moves relatively. It is used to transfer images onto paper. That is, the head is heated by passing a current corresponding to the I word to the thermal head for an arbitrary period of time. The heat transmitted through the substrate melts or sublimates the ink layer, and the melted or sublimated ink layer adheres to plain paper. When the medium and plain paper are gradually peeled off, the ink layer leaves the substrate and becomes completely normal. transferred onto paper. In this way, characters and images are printed on plain paper.

The transfer medium for thermal recording in the present invention has an ink layer on a substrate, and this ink layer is made of an oligomer resin having a number average molecular weight of 30,000 or less and an ethylene-vinyl acetate copolymer,
Contains pigment or dye.

Therefore, it has excellent uniformity of transferred characters and images during use, and also has excellent effects on print clarity, storage stability, abrasion resistance, and transferability.

(2) Specific Examples of the Invention Below, specific examples of the present invention will be shown to explain the present invention in further detail.

(Example) 3.5μI thick polyethylene terephthalate (PUT)
Using a resin film as a base, various ink layers having the following compositions were applied using a predetermined solvent using a gravure coating method to prepare the samples shown in Table 1.
Note that the numerical value in parentheses is the number average molecular weight of the resin.

Ketone resin oligomer (molecular weight 1300) 4 Ethylene-vinyl acetate copolymer (EVA, vinyl acetate 28wt%, molecular weight 20000) 1 Brilliant carmine 6B 1 reduction 4 parts by weight Polyamide copolymer oligomer (molecular weight 3000) 10 Ethylene-acetic acid Vinyl copolymer, (EvA vinyl acetate 28w1.% molecular weight 25000) 0.5 1ionol 1ueFG 7351
1 Ko 4 Kyu Ml Difference J mm part Tsukumaron indene resin (molecular weight 1100) 7 Ethylene-vinyl acetate copolymer (EVA vinyl acetate 3511% molecular weight 16000) 2 Sanyo Fast Red F 6
RIL Sukuri 1 difference 1 parts by weight Polyester oligomer (molecular weight 2000) 6 Ethylene-vinyl acetate copolymer (EVA vinyl acetate 32wt, % molecular weight 28000) 0.7 Benzidine Yellow 2 G R1 Fuji Riho Part by weight ketone resin oligomer (Molecular weight 1300) 4 Ethylene-vinyl acetate copolymer (EVA Vinyl acetate 28wt% Molecular weight 21000) 1 Oleosol Fast Blue EL IL Suzuki J (Comparison) The number average molecular weight of the ketone resin used in Ink Layer Composition 1 It was made of toooooo acrylic resin. Other than that, the composition was the same as ink layer composition 1.

Ink - Hihongbuyu (comparison) In ink layer composition 1, the ethylene-vinyl acetate copolymer was excluded. Other than that, the composition was the same as ink layer composition 1.

The characteristics shown below were measured for the various samples thus prepared.

(1) Uniformity of transfer density The sample described in 2 was used as a transfer medium for thermal recording, the recording power of the thermal head was 0.6 W/dot, and the pulse width was 1.5.
A continuous P transfer of 1 m was performed on the rough paper using m5ec.

The minimum value with respect to the maximum value of these transfer densities was expressed in % and was taken as the uniformity value of the transfer densities.

The transfer density was measured using Sakura Microdensitometer PDM.
-5 (manufactured by Konishiroku Photo Industry Co., Ltd.).

The results are shown in Table 1.

Table 1 No. Composition Uniformity (
% ) 1 Ink layer composition 1 952
Ink layer composition 2 86 '3 Ink layer composition 3 854 Ink layer composition 4
855 Ink layer composition 5 956 (Comparison) Ink layer composition 68 7 (Comparison) Ink layer composition 7 21 From the results in Table 1, the effects of the present invention are clear.

Furthermore, it was confirmed that the print clarity, storage stability, abrasion resistance, and transferability were also at the same level or higher than conventional ones.

Claims (1)

[Claims] (1) A thermal recording transfer medium having an ink layer on a substrate, characterized in that the ink layer contains a resin having a number average molecular weight of 30,000 or less, an ethylene-vinyl acetate copolymer, and a pigment or dye. Transfer medium for thermal recording.