JPH01275094A - Thermal transfer ink and ink film - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a thermal transfer ink and an ink film, and more particularly to a thermal transfer ink and an ink film containing a specific polyester resin.

[Prior art and problems to be solved by the invention] A thermal transfer ink film is a film in which at least one coloring material layer (ink N) is coated on a support such as paper or plastic film, and solid ink is heated. Recording is performed by melting ink and transferring it onto recording paper. Methods for heating the ink film include heating with a heating element from the side opposite to the coloring material layer coating surface or from the coating surface side of the coloring material layer through recording paper, and energization heating using a resistive layer provided on one layer constituting the ink film. There are methods such as heating.

The coloring material layer is made of a heat-fusible substance containing a pigment or dye as a coloring material. As the heat-melting substance, heat-melting materials such as carnauba wax and paraffin wax are used. Also,
As the support, polyethylene terephthalate film, polycarbonate film, etc., which have excellent surface smoothness and dimensional stability, are generally used.

When recording a transferred image on plain paper using such a thermal transfer ink film, for example, a thermal transfer printer equipped with a thermal head is generally used, but it is desirable to keep the thermal energy required for printing as low as possible. It will be done. By keeping the thermal energy required for printing lower than before, the cycle time for heating and cooling the head is shortened, making it possible to speed up printing, as well as preventing thermal deterioration of the head and improving the This is because it becomes possible to downsize the power supply. Moreover, the lack of heat resistance of the base film can be compensated for.

However, if the melting point of the ink composition is designed to be low in order to increase the transfer sensitivity of the ink film for thermal transfer, when printing on plain paper, background stains due to the low melting point components of wax occur, resulting in poor print fixation and fastness. It is not easy to realize this because not only the temperature decreases, but also the so-called blocking phenomenon occurs when the environmental temperature rises during storage.

In order to solve these problems, attempts have been made to add various thermoplastic polymer compounds, including polyethylene wax (Japanese Unexamined Patent Publication No. 101094/1983), ethylene-alkyl acrylate copolymer (Japanese Unexamined Patent Application Publication No. 60/1988), -120
No. 092), 1,2-polybutadiene (Japanese Unexamined Patent Publication No. 1983)
0-127193) and the like in an ink composition to perform low-energy printing without background smudge.

All of these methods use a thermoplastic polymer compound as an additive to a low-melting wax as a main component, and use the polymer network structure to increase the strength of the coating film and prevent surface staining. has its limits.

Also, as a heat-melting substance for thermal transfer ink, JP-A-62
Low molecular weight polyesters such as those disclosed in Japanese Patent Publication No. 216790 have been proposed, and have high transfer sensitivity (low energy printing is possible), but such low molecular weight polyesters are resistant to solvents at low temperatures below 15°C. Since the solubility is low and crystals tend to precipitate, the viscosity of the ink becomes high, making it difficult to apply, and the resin is hard and brittle, resulting in poor ink film strength.

In addition, thermal transfer printers are widely used as compact, lightweight, and inexpensive popular printers. In particular, it has been adopted almost 100% of the time in fields such as personal word processors, taking advantage of its maintenance-free features.

As described above, the thermal transfer printing system has many advantages as a popular printer, but as thermal transfer printers become more popular in the future, the cost of consumables is high and the printing cost per sheet is relatively high. It is expected that this will be the biggest obstacle. The reason for this high cost is that each cassette must be produced in small quantities and of high quality due to the need to supply cassettes for various models, and that the price of cassettes, which are peripheral parts other than consumables, is higher than ribbons. It is quite expensive, it is difficult to automate a series of post-processes such as slitting, core winding, and cassette packing, resulting in high labor costs, and furthermore, distribution costs are high.

Therefore, it is desired to reduce printing costs by using the same ink ribbon many times.

[Means to solve the problem]

Therefore, as a result of intensive studies to solve the above problems, the present inventors have found that polyester resin, which has a specific melting point range and molecular weight range and has specific bonds, is used as a heat-melt material as the main component of heat-melt ink. It has been found that by selecting the appropriate amount, it is possible to obtain a thermal transfer ink with high transfer sensitivity that has high coating strength and enables low-energy printing without scumming. That is, a polyester resin is used that has a melting point (DSC method) of 50 to 110, a C1 number average molecular weight of 300 to 6,000, and contains 1 to 30 ethylenically unsaturated bonds in the main chain and/or side chain of the polymer. This improves the solubility in solvents and suppresses crystal precipitation at low temperatures.
There is little increase in ink viscosity, so the ink has good fluidity and is easy to apply even in winter. 2) The polyester resin becomes flexible and reduces drying shrinkage when ink is applied to a film, resulting in a finished ink ribbon. The present inventors have discovered that effects such as increasing the strength of the coating film can be obtained, and have completed the present invention.

That is, the present invention has a melting point (DSC method) of 50 to 110°C.
It is characterized by containing a polyester resin having a number average molecular weight of 300 to 6,000 and containing 1 to 30 ethylenically unsaturated bonds in the main chain and/or side chain of the polymer, and a colorant as essential components. The present invention provides an ink for thermal transfer, and an ink film for thermal transfer, characterized in that the ink is coated on one side of a support.

The ink of the present invention can be used as an ink for multiple printing, which reduces printing costs by using the same ink ribbon many times. Thermal transfer printing system uses heat-melting ink coated on a base film such as polyethylene terephthalate (PET) film, which is heated from the back side of the base film by a thermal head to melt it and sufficiently penetrate or adhere to the receiving paper. This system then transfers the ink from the base film side to the transfer paper side by mechanically separating the base film and the transfer paper. When conventional ink ribbons are used, the ink cools and solidifies during peeling, and the entire amount of heated and melted ink is transferred to the transfer paper, resulting in a disposable ink ribbon that can be used only once. However, when a ribbon made of the ink film of the present invention is used, the ink remains in a molten state even when the film and transfer paper are separated. As a result, the ink is cut from the middle, and not the entire amount of the heated and melted ink is transferred to the transfer paper, thereby achieving multiple printings.

The polyester resin used in the present invention is a saturated polyhydric alcohol and/or a polyhydric alcohol containing an ethylenically unsaturated bond, and a saturated polyhydric carboxylic acid and/or a polyhydric carboxylic acid containing an ethylenically unsaturated bond. It is necessary that at least one of the alcohol side and the acid side contains a component containing an ethylenically unsaturated bond.

The presence of ethylenically unsaturated bonds in the polyester resin of the present invention obtained by polymerizing components containing ethylenically unsaturated bonds can be confirmed by NMR and IR measurements.

The polyester resin of the present invention must contain 1 to 30 ethylenically unsaturated bonds in the main chain and/or side chain of the polymer, and if the number of ethylenically unsaturated bonds exceeds 30, the melting point will decrease. It's too low and I don't like it. Also, actually 3
It is difficult to introduce more than 0 pieces.

Examples of the saturated polycarboxylic acids constituting the polyester resin of the present invention include oxalic acid, malonic acid, succinic acid,
Geltar acid, adipic acid, pimelic acid, azelaic acid, sepatic acid, nonanedicarboxylic acid, decanedicarboxylic acid, undecanedicarboxylic acid, dodecanedicarboxylic acid,
Diglycolic acid, n-butylsuccinic acid, isobutylsuccinic acid, n-octylsuccinic acid, isooctylsuccinic acid,
Examples include n-dodecylsuccinic acid, isododecylsuccinic acid, hexahydroterephthalic acid, lower alcohol esters thereof, and acid anhydrides thereof. These saturated polyhydric carboxylic acids can be used alone or in combination of two or more.

Examples of the polycarboxylic acid containing an ethylenically unsaturated bond constituting the polyester resin used in the present invention include dibasic acids having 4 to 24 carbon atoms containing an ethylenically unsaturated bond (e.g., fumaric acid, maleic acid, Itaconic acid, citraconic acid, traumatic acid, ULB-20 manufactured by Intermediate Oil Co., Ltd.
, IPU-22 and its lower alcohol esters and its acid anhydrides, etc.); Polymerized fatty acids obtained by polymerizing drying oil or semi-drying oil fatty acids (e.g. tall oil fatty acids, etc.) generally called dimer acids; Butenyl succinic acid, Examples include alkenylsuccinic acids such as octenylsuccinic acid and dodecenylsuccinic acid and their ax hydrates; muconic acid; polybutadiene dicarboxylic acid; tetrahydrophthalic acid and its acid anhydrides.

Examples of the saturated polyhydric alcohol constituting the polyester resin used in the present invention include ethylene glycol,
Propylene glycol, butanediol, triethylene glycol, tetramethylene glycol, pentamethylene glycol, hexamethylene glycol, heptamethylene glycol, octamethylene glycol, nonamethylene glycol, decamethylene glycol, undecamethylene glycol, dodecamethylene glycol, trideca Methylene glycol, tetradecamethylene glycol, octadecamethylene glycol, eicosamethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, hexaethylene glycol, glycerol, pentaerythritol, neopentyl glycol, dipropylene glycol, polyethylene glycol, polypropylene glycol , polytetramethylene glycol, cyclohexane dimetatool, and the like. These saturated polyhydric alcohols can be used alone or in combination.

The polyhydric alcohol containing ethylenically unsaturated bonds constituting the polyester resin used in the present invention includes 1
．． 4-butynediol, polybutadiene diol, guimerdiol (hydrogenated dimer acid), reaction products of the aforementioned ethylenically unsaturated bond-containing polyhydric carboxylic acids and alkyl glycidyl ethers (for example, the following Compound HOOCRICOO obtained by the reaction shown in the reaction formula
H+ 2RZ-0-CIlt -CH-CIlin\1 RzOCHtCHCHzOOCR+C00CIl□-C
Examples include HCHzORz0 HOH (wherein R1 represents an alkylene group containing an ethylenically unsaturated bond, and R2 represents an alkyl group).

Particularly preferable combinations of the constituent components of the polyester resin used in the present invention include ethylene glycol, butanediol, hexamethylene glycol, and decamethylene glycol as the saturated polyhydric alcohol, and succinic acid and adipic acid as the saturated polyhydric carboxylic acids. , a combination selected from cepatic acid, an ethylenically unsaturated bonded gold, and a polybasic acid. To explain such a system in more detail, the following ■
Combinations shown in ~■ can be mentioned.

■ Ethylene glycol (1 mol), cepatic acid (0,
9 mol), ethylenically unsaturated gold-containing polybasic acid (0,1
mole) combination.

■ Hexamethylene glycol (1 mol), cepatic acid (0.9 mol), ethylenically unsaturated gold-containing polybasic acid (
0.1 mol) combination.

■ Decamethylene glycol (1 mol), adipic acid (
0.9 mol), ethylenically unsaturated gold-containing polybasic acid (0.9 mol), ethylenically unsaturated gold-containing polybasic acid (0.
, 1 mole).

When the polyester resin obtained by these combinations has a melting point of 50 to 110°C and a number average molecular weight of 300 to 6,000, it is particularly useful as a heat-melting material for thermal transfer ink.

The polyester resin of the present invention has a lower degree of polymerization than conventional polyethylene terephthalate-based polyester resins,
It is an ester oligomer that has a relatively low melting point and melts in a narrow temperature range, and is suitable as a heat-melting material for thermal transfer inks.

The number average molecular weight and melting point of the polyester resin of the present invention are usually a number average molecular weight of 300 to 6,000 calculated from the terminal group and a melting point of 50 to 110°C by DSC method, but preferably a number average molecular weight of 500 to 4,000 and a melting point range of 55 ~
The temperature is 100°C, and any known method for synthesizing these may be used. If the melting point is less than 50°C, blocking of the thermal transfer ink film occurs, resulting in a lack of stability during storage and use.

If the melting point exceeds 110°C, the thermal stability is good, but the sensitivity is lowered, making it impractical.

When the number average molecular weight of the polyester resin is less than 300, the melting point is often less than 50°C, and blocking is likely to occur. Furthermore, when the number average molecular weight of the polyester resin is greater than 6000, the cohesive force is too strong, making transfer difficult and often resulting in a decrease in sensitivity.

The polyester resin of the present invention is a so-called crystalline polymer that has a clear melting point when measured by the DSC method.
It has completely different properties from the non-quality polyester (which does not have a clear melting point) described in Publication No. 2-13384.

However, it may contain a component containing an aromatic double bond within a range that exhibits a clear melting point.

Polyester usually has a -COOII group and a -0H group at the end of its molecular chain. Utilizing these functional groups, through condensation reactions, ionic reactions, polymer reactions, etc., modified polyesters, blocking copolymers containing polyesters, and graft copolymers can be produced as heat-melting materials for the thermal transfer ink of the present invention. May be used. Further, by utilizing the double bonds in the molecule, it may be used as a heat-melting material for the ink for leisurely transfer of the present invention in the form of a modified or graft copolymer containing polyester.

For example, fatty acids and higher alcohols such as stearic acid and stearyl alcohol can be modified by reacting with 1COOII or 10H groups at the terminals of polyester, or can be modified by reacting with isocyanates or amines. Modification by reaction with silicone compounds, epoxies, phenols, etc. is also possible. In addition, it can be further condensed with a mainly crystalline aliphatic polyester to form a block copolyester, or by utilizing double bonds in the molecular chain, etc.
Containing polyester by polymerizing one or more types of vinyl polymerizable monomers such as styrenes such as styrene and α-methylstyrene, methacrylic esters such as methyl methacrylate and butyl acrylate, and acrylic esters in the presence of polyester. A graft copolymer can be obtained. Furthermore, zinc acetate, zinc oxide, etc. can be added to form ionic crosslinks with terminal carboxylic acids.

The polyester resin used in the present invention may be used alone or in combination with two or more polyester resins, or waxes that have been widely used in the past such as paraffin and carnauba wax, rosin derivatives such as hydrogenated rosin and ester gum, It may be used in combination with polyethylene wax, ethylene-alkyl acrylate, etc.

The thermal transfer ink of the present invention contains at least one of the above polyester resins and at least one colorant as essential components. The content of the polyester resin is preferably 40 to 80% by weight in the solid ink, and the content of the colorant is 10 to 10% in the solid ink as the total amount of pigment and dye.
30% by weight is preferred.

Coloring agents used in the present invention include black dyes and pigments such as carbon black, oil black, and graphite; C, 1,
Pigment Yellow 1, 3, 74,
C,1,Pigm 97, 98 etc. a7toacetate arylamide type monoazo yellow pigment (fast yellow type); C,1,Pigm
Acetoacetate arylamide disazo yellow pigments such as entYellow 12, EntYellow 13, EntYellow 14; C, 1,5
olive Yellow19, 77, 79, C
, 1, Yellow dye such as Disperse Yellow 164; C, 1, Pigment Red 48, Disperse Yellow 4
9:1, 53:l, 57:1, 81, 122,
5th grade red or red pigment 2C,1,5olvent
Red dyes such as Red 52, Red 58, Red 8; C, 1, P
Examples include blue dyes and pigments such as copper phthalocyanine and its derivatives and modified products, such as igment Blue 15:3, and dyes and pigments well known for conventional printing inks and other coloring applications, such as colored or colorless sublimation paints.

These colorants may be used alone or in combination of two or more. Of course, the color tone may be adjusted by mixing with an extender pigment or a white pigment. Furthermore, in order to improve the dispersibility of heat-melting material components, the surface of the colorant may be treated with a surfactant, a coupling agent such as a silane coupling agent, or a polymeric material, or a polymeric material such as a polymeric dye or a polymeric graph+. -A material may also be used.

The ink film for thermal transfer of the present invention has at least one coloring material layer coated with the above-mentioned ink in contact with a base film as a support or a coating layer on the base film, and additionally has an overcoat layer or It may also have a resistance layer for energization and heat generation, etc. as other constituent layers.

The support used in the ink film for thermal transfer of the present invention is preferably a support that has heat-resistant strength, high dimensional stability, and surface smoothness. In addition to polyethylene terephthalate, resin films of polycarbonate, polyethylene, polystyrene, polypropylene, polyimide, etc. having a thickness of 2 to 20 microns are preferably used.

〔Example〕

EXAMPLES Hereinafter, the effectiveness of the present invention will be shown by Examples, but of course the present invention is not limited thereto. Parts in the examples are parts by weight.

In addition, in the following examples, the melting point, number average molecular weight, and N
? IR and IR were measured as follows.

・Melting point [differential scanning calorimetry (DSC) method] The melting point is determined by measuring 4.5 mg of a sample at a heating rate of 5°C/win using a Rigaku Denki DSC-10A measuring device, and determining the temperature at the top of the endothermic peak. is the melting point.

・Acid value of number average molecular weight polyester resin (AV, JIS K-800
6) and the hydroxyl value (OHV, JIS L8006) were measured, and the number average molecular weight was determined using the following formula.

・NMR Polyester resin was dissolved in deuterated chloroform containing 51% of 7M, and VARIAN T-60 type NMR7! .

Proton NMR was measured using a pectrometer.

・IR K using Hitachi manufactured fracture 270-30 type infrared spectrophotometer
IR was measured using the Br method.

Example 1 Hexamethylene glycol 354g, cepatic acid 485g
g, 70 g of fumaric acid and 450 mg of hydroquinone at 1
A thermometer, a stirring bar, a falling condenser, and a nitrogen inlet tube were attached to the flask, and polycondensation was carried out at 180'C under a nitrogen stream in a mantle heater to obtain a polyester with a melting point of 61'' and a C1 number average molecular weight of 2500. Resin was obtained.

The NMR of this polyester resin was measured, and the chemical shift δ
= 6.81) I) In 11, a proton derived from an ethylenically unsaturated bond was confirmed (Fig. 4). In addition, IR was measured and it was confirmed that there was an absorption peak at 1660 cm-' derived from the C=C stretching vibration of the non-conjugated olefin (Figure 5).

That is, it was confirmed that this polyester resin contained ethylenically unsaturated bonds.

Next, using this polyester resin, a mixture having the composition shown below was kneaded in a ball mill for 12 hours to prepare a thermal transfer ink.

Polyester resin 15 parts Ethylene/vinyl acetate resin 3 parts Carnauba wax
6 parts carbon black 6 parts toluene 70 parts This ink 6 parts
Coated with a wire bar on μ polyethylene terephthalate film (Toshi, Lumirror), and the dry coating film was approximately 3.
An ink film for thermal transfer was prepared by providing a coloring material layer of 100 g/m''.

The thermal transfer ink film created in this way was printed on a line-type thermal transfer printer (NIP 5234°9.4).
Printing was performed on plain paper (BEKK 160 seconds) using Dot/III+9 (manufactured by NEC Corporation), and the density of the transferred image was measured. In order to examine the relationship between printing energy and transferred image density, we operated the density adjustment lever to change the pulse width of the applied voltage by 0.65 to 0.85 seconds, and measured the transferred image density using a Macbeth densitometer (model RD 918). It was measured. the result,
The pulse width of the applied voltage necessary to obtain a transferred image with a density of 1.2 was 0.66 seconds.

No scumming was observed during printing.

In addition, in order to examine the blocking resistance, five sheets of the above thermal transfer ink film were stacked and stored under a pressure of 500 g/cm for one week, and then the films were taken out and observed for the presence or absence of blocking, but no blocking was observed. Furthermore, even when this ink film was rubbed by hand, the ink did not fall off and showed strong coating strength.

Example 2 Hexamethylene glycol 236g, cepatic acid 384g
Example 1
Condensation polymerization was carried out at 180'C in the same manner as above, and the melting point was 6.
A polyester resin having a number average molecular weight of 11,745 was obtained at 3°C.

An ink having the same composition as in Example 1 except for using this polyester resin was prepared, an ink film was produced, and the same printing evaluation as in Example 1 was performed. The density after transfer was measured using a Macbeth densitometer (model RD 918), and the density was 1.
0.0 during the pulse of applied voltage necessary to obtain the transferred image No. 2.
It was 66 seconds.

Further, even when this ink film was rubbed by hand, the ink did not fall off and the film showed strong coating strength.

Example 3 354 g of 1,6-hexanediol, 546 g of cepatic acid
g, dodecenylsuccinic anhydride (manufactured by Sanyo Chemical) 40g
was charged into a 12-four-eye flask, and polycondensation was carried out at 180''C in the same manner as in Example 1 to obtain a polyester resin with a melting point of 64°C and a number average molecular weight of 131,784.

An ink having the same composition as in Example 1 except for using this polyester resin was prepared, an ink film was produced, and the same printing evaluation as in Example 1 was performed. As a result of measuring the density after transfer, the duration of the applied voltage pulse required to obtain a transferred image with a density of 1.2 was 0.67 seconds.

Further, even when this ink film was rubbed by hand, the ink did not fall off and the film showed strong coating strength.

Comparative Example 1 Paraffin wax 60 parts Carnauba wax 25 parts Carbon black
15 parts The above composition was dispersed in an attritor at 100°C for 4 hours to prepare a thermal transfer ink. This ink was hot-melt coated onto the 6μ polyethylene terephthalate film used in Example 1 to a film thickness of 3.5μ to prepare an ink film for thermal transfer.

When printing was attempted on this thermal transfer ink film in the same manner as in Example 1, the voltage was 0 during the pulse of the applied voltage.
．． In the case of 65 seconds, only a transferred image with a density of 0.20 was obtained. Further, the duration of the applied voltage pulse required to obtain a transferred image with a density of 1.2 was 0.85 seconds.

Furthermore, when this ink film was rubbed by hand, the ink caused surface peeling, and the strength of the coating film was very weak.

Comparative Example 2 Hexamethylene glycol 354g, cepatic acid 606g
In the same manner as in Example 1, a polyester having a melting point of 67° C. and a number average molecular weight Lt of 1900 was synthesized from G.

When the NMR of the obtained polyester resin was measured, there was no peak in the vicinity of chemical shift δ-6 and 8 (Fig. 6).

Further, when IR was measured, there was no peak near 1660 cm-' (Fig. 7). In other words, NMRSIR indicates that the polyester does not contain ethylenically unsaturated bonds (+I
Approved.

Next, using this polyester, an ink having the same composition as in Example 1 was prepared, and an ink film was prepared.
The same printing evaluation as in Example 1 was performed. As a result of measuring the density after transfer, the duration of the applied voltage pulse required to obtain a transferred image with a density of 1.2 was 0.67 seconds, indicating high sensitivity. However, when the ink film is rubbed by hand, the ink often falls off.

Test Example 1 Measurement of the solubility in toluene of the polyester resins obtained in Examples 1, 2.3 and Comparative Example 2 (here, solubility is the solid content concentration in the solution expressed as a weight percentage) The results are shown in Figure 1.

As is clear from FIG. 1, Example 1. 2. It can be seen that the polyester resin containing ethylenically unsaturated bonds in the molecule obtained in Example 3 has a higher solubility in toluene than the saturated polyester resin obtained in Comparative Example 2, and less crystal precipitation occurs even at low temperatures.

Test Example 2 The viscosity of the inks obtained in Example 1.2 and Comparative Example 2 was measured at different temperatures, and the results are shown in FIG.

As is clear from FIG. 2, the inks obtained in Examples 1 and 2 show little increase in viscosity at low temperatures.

This is best understood by the solubility diagram shown in FIG.

Example 4 Polyester resin obtained in Example 1 (melting point 61"C,
Using a freezing point of 53゛C2 number average molecular weight of 2500>,
A mixture having the composition shown below was kneaded in a ball mill for 12 hours to prepare a thermal transfer ink.

Polyester resin 15 parts ethylene/vinyl acetate resin 3 parts carnauba wax 6 parts carbon flank 6 parts toluene
70 copies of this ink was applied to a 6μ polyethylene terephthalate film to give a dry coating film of approximately 7 g/m'', and the printing was evaluated using a commercially available thermal transfer printer (Personal Word Processor Bungo Mini 7E manufactured by NEC). .Evaluation was performed using continuous black solid printing.

The same part of the ribbon was used multiple times, and the change in print density (measured by Macbeth) with respect to the number of prints was measured. The results are shown in FIG.

As is clear from FIG. 3, the optical density (00) maintained at 1.0 or higher until the third printing, demonstrating high performance as an ink for multiple printing. Further, even when the ink ribbon was rubbed by hand, the ink did not fall off and the coating film showed strong strength.

Comparative Example 3 Wax manufactured by Nihon Tankou Co., Ltd. instead of polyester resin)
Using INF-10 (melting point 75°C, freezing point 75°C),
Other than that, an ink having the same composition as in Example 4 was prepared, an ink film was prepared, and the printing was evaluated in the same manner as in Example 4.

The results are shown in FIG. 3. Almost all of the ink was transferred during the -th printing, making repeated use completely impossible.

〔Effect of the invention〕

As described above, according to the ink film for thermal transfer of the present invention, the melting point (DSC method) is 50 to 110, the C1 number average molecular weight is 300 to 6000, and the main chain and/or side chain of the polymer has 1 Since polyester resin containing ~30 ethylenically unsaturated bonds is used as the heat-melting material, the transfer rate is high, low-energy printing is possible, and it is suitable for high-speed printing. Furthermore, there is no uneven transfer, the fastness of printing does not deteriorate, and since the content of components with low melting points below 50°C is extremely small, there is no fear of blocking.

Furthermore, there is relatively little tendency for the ink viscosity to increase at low temperatures (below 15°C), resulting in a paint that has good fluidity and is easy to apply even in winter. Furthermore, the coating strength of the ink film was sufficient for practical use.

Furthermore, a ribbon made of an ink film produced using the thermal transfer ink of the present invention can be printed multiple times,
We were able to achieve low printing costs.

[Brief explanation of the drawing]

Figure 1 is a graph showing the results of Test Example 1, Figure 2 is a graph showing the results of Test Example 2, and Figure 3 is Example 4 and Comparative Example 3.
Figure 4 is a graph showing the change in printing density with respect to the number of printings of the ink film of Example 1.
MR spectra, FIG. 5 shows the IR spectrum of the polyester resin of Example 1, FIG. 6 shows the NMR spectrum of the polyester resin of Comparative Example 2, and FIG. 7 shows the IR spectrum of the polyester resin of Comparative Example 2. Applicant's agent Kaoru Furuya Figure 1 Temperature (r) Figure 2 Temperature (71-)

Claims (1)

[Claims] 1. The melting point (DSC method) is 50 to 110°C, the number average molecular weight is 300 to 6,000, and the polymer has 1 to 30 ethylenically unsaturated bonds in the main chain and/or side chain. A thermal transfer ink characterized by containing a polyester resin containing as essential components, and a colorant. 2. A polyester resin having a melting point (DSC method) of 50 to 110°C, a number average molecular weight of 300 to 6000, and containing 1 to 30 ethylenically unsaturated bonds in the main chain and/or side chain of the polymer, and An ink film for thermal transfer, characterized in that it is formed by applying a thermal transfer ink containing a colorant as an essential component to one side of a support.