JPS62158092A - Thermal transfer material - Google Patents

Abstract

PURPOSE:To obtain a thermal transfer material excellent in uniformity of transferred characters or images, clearness of printed images, preservation stability, abrasion resistance and transfer properties, by providing an ink layer which comprises a binder resin and a pigment having a particle diameter within a predetermined range. CONSTITUTION:An ink layer comprising a resin and a pigment is provided on a base, the pigment being so conditioned that the average particle diameter (d) of the pigment is 0.1-0.7mum and at least 60% of all particles of the pigment have a diameter of 0.6d-1.8d. If the number of the particles having a diameter of 0.6d-1.8d is less than 60% of the total number of the particles, printed density will be low, fixability and optical characteristics such as gloss will be poor, and uniform printing can not be achieved. If the average particle diameter (d) is less than 0.1mum, transmittance of a printed ink is raised, so that printed density is lowered. If the average particle diameter (d) is more than 0.7mum, transferring capability is lowered, and optical characteristics such as gloss of printed images become poor. In addition, uniform printing can not be achieved, and properties for fixation onto a paper become poor.

Description

DETAILED DESCRIPTION OF THE INVENTION ■ Background Technical Field of the Invention The present invention relates to a thermal transfer material. For more details, please refer to facsimiles, computer printers, OA
This invention relates to the improvement of the ink layer of thermal transfer materials used in equipment such as output printers and various recorders.

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

Thermal recording using such thermal transfer materials has the following advantages: colored characters and images can be easily obtained by heating means, no complicated development process is required, and the hardware used is a relatively compact and simple device. It has advantages.

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

Thermal transfer materials used in such recording methods are usually
It is formed by coating an ink layer containing a colorant and a resin on a substrate.

Various reports have been made regarding such thermal transfer materials, including improvements in print clarity and storage stability (Japanese Patent Application Laid-Open Nos. 53-81246, 55-39381,
No. 58-199195), improvements related to wear resistance (
JP-A No. 58-201693), Improvements regarding print clarity, adhesion to substrates, and transferability (JP-A No. 59-291)
No. 96) etc.

However, in practical use, image density, hiding power, uniformity and sharpness of transferred characters and images, transferability to so-called rough paper, etc. are not yet satisfactory.

■ Purpose of the invention The purpose of the present invention is to provide excellent image density and hiding power,
It is an object of the present invention to provide a thermal transfer material that has excellent image uniformity, and also has excellent print clarity, storage stability, abrasion resistance, and transferability.

■Disclosure of invention Such objects are achieved by the invention described below.

That is, the present invention provides a thermal transfer material having an ink layer containing a resin and a pigment on a substrate, in which 60% or more of the total number of pigment particles are 0. The material is a heat-sensitive transfer material characterized by being within the range of 6d to 1.8d (d is the average particle diameter of the pigment).

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

The thermal transfer material of the present invention (hereinafter simply referred to as thermal transfer material) has an ink layer on a substrate. This ink layer contains resin and pigment.

The pigment used in the present invention accounts for 60%, more preferably 70% of the total number of pigment particles, when the average particle size is 1.
The above is within the range of 0.6d to 1.81. When the total number of pigment particles in this range is less than 60%, print density decreases, optical properties such as fixing properties and glossiness deteriorate, and uniform printing becomes impossible.

The average particle diameter 1 is 0.1 to 0.7 μI, more preferably 0.3 to 0.5 μm. If this value is less than 0.1 μm, even if the same amount of ink is printed, the transparency will be high, resulting in a decrease in print density. On the other hand, if the thickness exceeds 0.7 μm, the transfer ability will decrease and the optical properties such as the glossiness of the print will deteriorate. Furthermore, it becomes impossible to print uniformly, and the fixability to paper deteriorates.

The average particle diameter of the pigment can be measured by electron microscopy (scanning microscope (SEM)), but as mentioned above, it is related to the total number of pigment particles, so in the present invention, the ink layer is Observe and measure the particle size of, for example, 100 randomly extracted particles under one field of view, and average this over, for example, 5 fields of view to determine the average particle size.

Note that the average particle size refers to a particle unit, and usually refers to a secondary particle that is an agglomeration of primary particles.

Pigments include azo dyes, anthraquinones, indigoids, soluble dyes, sulfide, carbonium, phthalocyanine, quinone imine, cyanine, nitroso, nitro, stilbene, quinoline, pyrazolone, 1: There are type 2 metal complex salts, benzoquinones, naphthoquinones, etc., but in the present invention, it is preferable to include them mainly to obtain monochrome characters and images.

The pigments separated into colored threads are 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 (
: armin 6B, 6B Tourer (sun rusted) Sy＋++uler Br1lliant Car
mine 6B (Dainippon Ink) Sanyo Br1lliant Carmine 6
B, 68N (Yamama dye) Sanyo Fast Re
d F6R (mountain pigment) Sanyo Lithol R
ubfn BKN (mountain pigment) Graph
ol Rubin BP (Sand) R
ubin Toner 4B, 4BA (
l CI ) Vulcafor C1aret Y
There are pigments such as (I' CI ).

(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) y-index) For example, Benzidine Yellow 2GR (Oguchi Kiseika) Symuier Fast Yellow GRF
(Dainippon Ink) Sanyo LightLFas
t Benzidine Yellow R (mountain pigment) Graphol Yellow GRBL
(Sand) Monolite Yellow GL
(I CI )Vynamon Yel
There are pigments such as low GRE (TCI).

(3) Blue and cyan) Azo type, phthalocyanine, dyeing is lake, condensation %I! 2
(Anthraquinone), Alkaline Blue, Daylight Fluorescence, specifically Pigment Blue 15 (Color Index) For example Lionoi Blue FG 7351
(Toyo Ink) Lionol Blue FG 739
3G (Toyo Ink) Graphol Bl
ue 2GLS (Sand) Monastr
al Fast Lolue BG
There are pigments such as (I CI ).

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

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 resin described below.

There are no particular restrictions on the resin used in the present invention, but
Among them, the resins shown below are preferred.

i) Polyolefin polyethylene, polypropylene, poly4-methylpentene-1, etc.

ii) Polyolefin copolymers such as ethylene-vinyl acetate copolymer, ethylene-acrylic acid ester copolymer, ethylene-acrylic acid copolymer, ethylene-propylene copolymer, ethylene-butene-1 copolymer, ethylene -maleic anhydride copolymer,
Ethylene propylene terpolymer (EPT), etc.

In this case, the polymerization ratio of the comonomers can be set to zero.

1ii) Vinyl chloride copolymer, for example, vinyl acetate-vinyl chloride copolymer, vinyl chloride-vinylidene chloride copolymer, vinyl chloride-maleic anhydride copolymer, acrylic ester or methacrylic ester and vinyl chloride copolymer, acrylonitrile-vinyl chloride copolymer, vinyl chloride ether copolymer,
Ethylene or propylene-vinyl chloride copolymer, ethylene-vinyl acetate copolymer with vinyl chloride graft polymerized, etc.

In this case, the copolymerization ratio can be arbitrary.

iv) Vinylidene chloride copolymer Vinylidene chloride-vinyl chloride copolymer, vinylidene chloride-vinyl chloride-acrylonitrile copolymer, vinylidene chloride-butadiene-vinyl halide copolymer, etc.

In this case, the copolymerization ratio can be arbitrary.

V) Polystyrene vi) Styrene copolymers 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-vinylidene 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 ester.

viii) Coumarone-indene resin Coumarone-indene-styrene copolymer.

1x) Terpene resin or picolite For example, terpene resin which is a polymer of limonene obtained from α-pinene, or picolite obtained from β-pinene.

X) Acrylic resin Particularly preferred are those containing an atomic group represented by the following formula.

Formula R10 ■ -CH2-C- -0R20 In the above formula, R10 represents a hydrogen atom or an alkyl group, and R20 represents a substituted or unsubstituted alkyl group.

In this case, in the above formula, R1G is preferably a hydrogen atom or a lower alkyl group having 1 to 4 carbon atoms, particularly a hydrogen atom or a methyl group. Also, R2O 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 R2H 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 atomic group represented by the above formula may form a copolymer with other repeating atomic groups to constitute various acrylic resins, but usually one of the atomic groups represented by the above formula An acrylic resin is formed by forming a homopolymer or copolymer in which the species or two or more species are 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-methyl methacrylate 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 reacting acrylonitrile with acetone.

x iv) Polyvinyl acetate xv) Vinyl acetate copolymers, such as copolymers with acrylic esters, vinyl ethers, ethylene, vinyl chloride, etc.

The copolymerization ratio may be arbitrary.

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

) (vii) 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; Nylon 6/6-6/6-1
0, nylon 6/6-6/12, nylon 6/6-6/
Polymers such as No. 11 or modified nylon may be used as the case may be.

xviii) Polyesters For example, various dibasic acids such as aliphatic dibasic acids such as oxalic acid, succinic acid, maleic acid, adipic acid, sebastenic acid, or aromatic dibasic acids such as isophthalic acid and terephthalic acid, and ethylene glycol. Condensates and co-condensates with glycols such as , 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 gliptal resin, which is a condensation product of phthalic anhydride and glycerin, is esterified and modified with a fatty acid, a natural resin, etc., and the like can also be suitably 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 iv) 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 condensates of mesitylene and formalin, or their Katsura-modified products, such as rosin-modified products.

xxvii) Petroleum resins C5 type, C9 type, C3-C9 copolymer type, dicyclopentadiene type, or copolymers or modified products thereof.

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

The number average molecular weight of these resins is 30,000 or less, especially 3
00 to 10000 is preferable.

When this number average molecular weight exceeds 30,000, transfer sensitivity
The uniformity of printing deteriorates, which is undesirable.

Further, it is preferable that the ink layer contains ethylene-vinyl acetate copolymer (EVA). 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 1,000.
It is about 200,000.

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

It is preferable that 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, based on 100 parts by weight of the above-mentioned resin.

Furthermore, in the ink layer, various waxes, various dyes, various oils, various ceramic particles, various polymers, dispersants, plasticizers, stabilizers, etc. are added in an amount of 0-1 to 100 parts by weight per 100 parts by weight of the resin. You may add about 1 part.

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 .mu.m, there will be problems such as decreased transfer sensitivity and loss of print clarity, and if it is less than 0.5 .mu.m, there will be problems such as insufficient print density.

An ink layer having such a thickness can be formed by various known layering methods, such as a melting method using hot melt, gravure coating, reverse roll coating, roll coating, air knife coating, dip coating, spinner coating, etc. A solution method may be used.

Substrates on which such ink layers are applied include polyethylene terephthalate (PET), polyethylene, polycarbonate, nylon, polyamide, polyimide, polyphenylene sulfide, polysulfone, wholly aromatic polyester, polyether ether ketone, polyether sulfone, and polyester. It is preferable to use a resin film such as etherimide.

The thickness of such a substrate is not particularly limited, but is usually about 0.8 to 20 μm.

Further, the shape of the base body is not particularly limited, and various shapes are possible. Further, the thermal transfer material of the present invention is preferably used for a single color, but may be used for multiple colors, and its structure may be of various known types.

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),
A back coat layer containing various metal layers such as silicone or fluororesin, various optical or electronic curing resins, various thermosetting resins, etc. may be provided.

■Specific effects of the invention In the thermal transfer material of the present invention, plain paper is placed on the ink layer constituting the thermal transfer material, and the heat generated by the thermal head that comes into contact with the back surface of the substrate of the material and moves relatively. The ink layer is transferred onto plain paper by brushing. That is,
The head is heated by passing a current in accordance with the signal through 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 the plain paper. When the medium and the plain paper are gradually peeled off, the ink layer leaves the substrate and completely forms the plain paper. transferred onto the . In this way, characters and images are printed on plain paper.

The thermal transfer material of the present invention has an ink layer on a substrate, and this ink layer contains a binder resin and a pigment having a predetermined particle size range.

For this reason, the uniformity of transferred characters and images during use is improved, and it 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) 3.5 μm thick polyethylene terephthalate (PUT)
A sample was prepared by using a resin film as a base, and depositing an ink layer having the composition shown below using a predetermined solvent by gravure coating on the base (sample No. 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 28wL% molecular weight 20000) 1 Carbon black manufactured by Mitsubishi Kasei (-particle size 240) 1 In this case, the secondary particles of carbon black Samples as shown in Table 1 were prepared with various particle sizes and particle size distributions.

The following properties were measured for these samples.

(1) Measurement of Recording Density The printing thickness was set within a range that provided a saturation density and did not disturb the uniformity of printed dots, and the recording density was measured. (Use a reflection densitometer to measure recording density.) (2) Measurement of adhesion to paper Record on high-quality paper, perform a tape test once, and calculate the amount of residual ink when the amount of ink in the test chamber is 100. ratio(%
) was investigated.

(3) Measurement of uniformity Variation (%) in solid printing of 100 m [ILIII1
The ratio (%) of the highest and lowest concentrations was measured using 12 units.

These results are shown in Table 1.

From the results in Table 1, the effects of the present invention are clear.

Claims (2)

[Claims] (1) In a thermal transfer material having an ink layer containing a resin and a pigment on a substrate, 60% or more of the total number of pigment particles is 0.6@d@~1.8@d@ (@d@ is A material for thermal transfer, characterized in that the average particle size of the pigment is within the range of 1. (2) The thermal transfer material according to claim 1, wherein the pigment has an average particle size of 0.1 to 0.7 μm.