JPH0553638B2 - - Google Patents

Description

[Detailed description of the invention]

[Technical Field of the Invention] The present invention relates to a thermal transfer recording paper and a thermal transfer recording device using the thermal transfer recording paper, and particularly relates to a thermal transfer recording paper suitable for high-speed color recording and a thermal transfer recording device using the thermal transfer recording paper. [Technical Background of the Invention and Problems Therewith] Thermal transfer recording devices, which have the advantages of requiring no maintenance and having low noise, are attracting attention in office automation. This thermal transfer recording device is based on the principle of forming a recorded image by thermally transferring ink, and therefore has a very simple structure. However, precisely because the principle is simple, the accuracy of ink transfer has a significant effect on the quality of recorded images. However, when thermal transfer recording is performed at high speed,
Missing dots 10 occur as shown in FIG. 1a, or when color recording is performed by overlapping multiple inks, missing dots 11 occur as shown in FIG. 1b. It was. Furthermore, in high-resolution recording, the above-mentioned problems become more pronounced, resulting in problems such as lack of sharpness of characters and color unevenness of color images. [Object of the Invention] An object of the present invention is to eliminate the above-mentioned drawbacks and provide a thermal transfer recording paper with a higher probability of ink transfer. At the same time, it is an object of the present invention to provide a thermal transfer recording device that produces high quality recorded images. [Summary of the Invention] In the thermal transfer recording method, the setting of ink on paper remains on the surface of the paper. This is because the heating time for ink is generally short, so the time for the ink to become flowable is shorter than the time for it to permeate into the paper. After this setting, dots are formed by separating the ink ribbon from the paper, so the degree of adhesion of the ink to the paper and the strength of the adhesion are key points in determining the quality of the dots. The various factors governing these will be explained using FIG. When the paper surface is smooth (Figure 2 a)
Under proper heating conditions, ink 20 adheres to paper 21 in deposition area 23 in approximately one-to-one relationship with heating area 22 . However, if the surface characteristics of the ink carrier film and paper are similar, the probability of transfer is only 50%, and stable dot formation is not guaranteed. Further, when the surface of the paper is rough (FIG. 2b), the ink 20 adheres to the paper 21 only in some places, as shown by the adhesion areas 24, and no image dots corresponding to the heating areas 22 are formed. In addition, if the ink 20 leaks poorly onto the paper 21 (FIG. 2c), even if the adhesion area 25 is secured, the adhesion strength will be weakened, or there will be areas where it does not adhere, and similarly, the heating area 22 It becomes difficult to form a corresponding image point. That is, the characteristics required of recording paper for thermal transfer recording are not just the smoothness of the paper surface. What is truly required is true contact of the ink with the recording paper and securing of that contact area. To be more precise, the determining factors are different between the case of contact between solid ink and recording paper and the case of contact between at least molten ink and recording paper. Consideration is required. The present invention was made from the above-mentioned viewpoints, that is, to secure an adhesion area according to the heating area and to improve the adhesion strength. The composition ratio (solid content) of pigment and binder in the layer is 100% pigment to 10-50% binder.
It is limited to. Furthermore, even better effects were found by using a pigment with an average particle diameter of less than 0.5 μm. Furthermore, a thermal transfer recording device compatible with high speed and color printing is constructed using the recording paper of the present invention as a component. [Effects of the Invention] With the thermal transfer recording paper of the present invention, even high-resolution pixels can be clearly formed with sufficient image density, thereby eliminating missing or missing pixels. In addition, it is possible to form dots with less thermal energy than before. Further, by using a thermal transfer recording apparatus using the thermal transfer recording paper of the present invention, a thermal transfer recording apparatus that outputs recorded images with high speed, high resolution, and high density can be obtained. Furthermore, a thermal transfer recording device that outputs color recorded images with excellent color reproducibility can be obtained. Furthermore, a thermal transfer recording device that saves energy and is highly economical can be achieved. Furthermore, a thermal transfer recording device can be created that can be used for both an ink adhesive thermal transfer recording method in which ink is melted or made sticky and adhered to paper, and an ink sublimation thermal transfer method in which ink is sublimated and adhered to paper. [Embodiments of the Invention] A thermal transfer paper according to the present invention and a thermal transfer recording apparatus using the same will be described in detail with reference to the drawings. FIG. 3 shows the structure of the thermal transfer recording paper according to the present invention. A coating layer 34 made of a pigment 32 and a binder 33 is provided on the surface of the base paper 31. The base paper 31 is generally medium-sized paper that has been suitably sized to bleached chemical pulps such as NBKP, LBKP, NBSP, and LBSP, mechanical pulps such as GP, RGP, and TMP, semi-chemical pulps, and chemical ground pulps, or unsized medium paper. , high-quality paper, a thermoplastic resin film such as polyester or polystyrene, or synthetic paper can be used, but the composition of the base paper itself is not particularly limited. Alternatively, a base paper smoothed by a supercalender or the like may be used. As the pigment 32, acicular inorganic pigments such as acicular soft calcium carbonate, preferably having an average major axis of less than 0.5μ, or powdered urea formaldehyde resins, powdered polystyrene resins, etc., preferably having an average particle diameter of less than 0.5μ are used. Particulate synthetic resins or synthetic silicas such as natural or white carbon with an average particle size of less than 0.5μ, inorganic pigments such as clay, talc, aluminum sulfate, titanium dioxide, zinc oxide, etc. can be used, preferably with an average particle size of less than 0.1μ. Synthetic silica such as white carbon, and inorganic pigments such as soft or heavy calcium carbonate can be used. The pigments used in the present invention are inorganic pigments and granular synthetic resins with the above-mentioned shapes and particle sizes, but if these specific pigments are included as pigment components in an amount of 30% or more, other pigments with shapes other than the above may be used. , a pigment with a particle size may be used in combination. In addition, inorganic pigments can be added to funnel oil,
By treating with a nonionic, cationic, or amphoteric surfactant such as sodium dodecyl sulfate, organic amine, metal soap, or sodium lignin sulfonate, the wettability of the ink rib with the ink is improved and it can be used suitably. The binder 33 is a rubber-based material such as styrene-butadiene rubber (SBR) or nitrile rubber (NBR).
Adhesive alone consisting of water-insoluble polymers such as vinyl chloride-vinyl acetate copolymer, acrylic resin, methacrylic resin, urethane resin, vinyl acetate-ethylene copolymer, ethyl cellulose, petroleum resin, etc.
Or solid waxes such as vegetable waxes such as carnauba wax and wood wax, animal waxes such as beeswax and slats wax, petroleum waxes such as microcrystalline waxes and paraffin waxes, and synthetic waxes such as oxidized waxes and ester waxes. It can be used in combination with wax. The requirements for the adhesive are film-forming properties and a small surface energy, preferably 40 dyn/cm or more. The ratio of solid wax to adhesive is 5~
50%, preferably 5-25%. This is because if the content is less than 5%, the effect of the wax mixture will be lost, and if it is more than 50%, problems will arise in film forming properties. As shown in the examples, the ratio of the pigment 32 and binder 33 forming the coating layer 34 is 10 to 50 parts of the binder to 100 parts of the pigment in terms of solid content. Preferably pigment 100
15 to 40. The coating liquid that forms the coating layer 34 includes various auxiliary agents, agents for making the coating film waterproof, agents for improving fluidity during coating, gloss finishing agents, preservatives, antifoaming agents, dyes, etc. You can enter it accordingly. The coating layer is formed using a conventional coating machine such as a blade coater, an air knife coater, a roll coater, or a bar coater, or a size press, a gate roll device, or the like. In addition, the surface of paper with only a coating layer is inferior in smoothness and uniformity.
After coating and drying, compress it with a super calender to adjust the smoothness. The thermal transfer recording paper according to the present invention has a Beck smoothness of 300 seconds or more and 2500 seconds or less, and an average surface roughness of 0.5 μ or more and 5 μ or less, preferably a Beck smoothness of 0.5 μ or more and 5 μ or less.
It has a surface characteristic of 500 seconds or more and 2000 seconds or less, and an average surface roughness of 1μ or less and 3μ or less. This has a Beck smoothness of less than 300 seconds and an average surface roughness.
If it is 5μ or more, the ink will not come into contact with the paper uniformly, causing cracked dots, etc.
Below this, the adhesion of the ink is insufficient and the ink often remains untransferred. This is particularly likely to occur when the paper surface becomes uneven due to previously transferred inks, such as in a color thermal transfer recording device that creates a color image by sequentially transferring a plurality of inks onto paper. Next, FIG. 4 shows the basic configuration of the thermal transfer recording apparatus according to the present invention. The ink ribbon 40 is transferred from an ink ribbon supply reel 41 to an ink ribbon supply roller 42.
It is played out by. The paper 43 is fed out from a paper supply reel 44 by an ink cylinder supply roller 45. The fed-out ink ribbon 40 and paper 43 are moved by rollers 46, 47 and platen roller 48.
An ink ribbon-paper pressure contact means 49 consisting of
The ink ribbon is pressed onto the platen roller 48 via the ink (not shown) of the ink ribbon. The ink ribbon 40 in the press-contact state is heated by a heating means 50 that selectively generates heat temporally and spatially according to recorded information by a drive circuit (not shown) from the opposite side to which the paper 43 is in contact. be done. Heating means 50
can be in contact with or out of contact with the ink ribbon 40 depending on the specific method. After the heating recording, the ink ribbon 40 is moved to the paper 43 at the roller 47 by the drive of the ink ribbon discharge port roller 51.
The film is peeled off and the ink is transferred. paper 4
3 is discharged to the outside of the apparatus by the paper discharge roller 52. Thermal transfer recording is completed by this series of processes. In the case of color recording, the conveyance control of the paper and ink ribbon differs depending on whether it is field sequential recording or line sequential recording, but this process is repeated depending on the number of colors. The ink ribbon 40 is made of a resin film of 4 to 20μ such as polyester, a base film such as paper such as condenser paper, solid waxes such as carnauba wax and paraffin wax, low molecular weight polyethylene, etc.
Pigments, dyes, or dispersible monoazo dyes commonly used in the printing field, such as carbon black and phthalonanine blue, are added to adhesives made of easily heat-meltable resins with a melting point of 65 to 150°C, such as petroleum resins. , dispersed anthraquinone dyes, anthracene dyes, and other sublimable dyes with a sublimation temperature of 65 to 200°C are dispersed in ink that is solid at room temperature and is applied in a coating amount of 2 to 20 g/m ² . In addition, there are various forms of ink application, such as a single color ribbon, a color ink ribbon in which multiple ink layers of different colors for approximately one screen are repeatedly provided in the longitudinal direction, or a color ink ribbon in which colored ink areas are divided in the longitudinal direction. , ribbon width and length can also be arbitrarily determined. Paper 43 is the paper according to the present invention. It can be used in the form of roll paper, cut paper, etc. The heating means 50 is a moving head type, a line head type thermal head, a CO ₂ laser,
Laser light such as Ar laser, thermal wire, thermal matrix type characters, etc. can be used. If the platen roller 48 cannot be heated without contact, such as a thermal head, it is preferable that the platen roller 48 is made of an elastic material such as silicone rubber so that the thermal head and the ink ribbon paper can be brought under appropriate pressure conditions. Further, it is preferable that the ink ribbon and paper move as one between the heating recording point and the peeling point. Next, a description will be given of the recording results obtained when the apparatus configured as described above is operated. The performance of the thermal transfer recording paper in this example was evaluated using a thermal head with a heating element density of 12 dots/mm, horizontal,
The following four items were evaluated using an evaluation device that records images at a resolution of 12 dots/mm in both vertical directions. The recording conditions such as recording voltage and applied pulse width were kept constant except for Sample No. 4, and ink ribbons 1, 2, and 4 were black ink ribbons with the same specifications, and Sample 3 was a color ink ribbon with the same specifications. . 1 Transfer establishment: Record dots consisting of 2 dots x 2 dots at a paper feed speed of 2.5 cm/min, observe the number of dots that are 7/8 or more of the regular dot size, and calculate the total number of dots observed. The percentage relative to 50 was calculated. 2 Resolution characteristic A; checkered pattern with side length n = n = 1, 2, 3,
4 and 6 (corresponding to resolutions of 12, 6, 4, 3, and 2 dots/mm, respectively), measured the transfer density with a Macbeth densitometer RD-2, and determined the maximum resolution in the area of equal density. I asked for it. 3 Resolution characteristic B: A checkered pattern with side length n = n=1, 2,...
(Equivalent to resolution 12, 6...dots/mm, respectively)
After recording the first color in the empty part of the checkered pattern, observe the dots of the second color under magnification and evaluate the shape of the dots in three stages: A, B, and C. did. Those that are close to square are rated A, those with slight chips are rated B, and those with significant chips are rated C. 4. High-speed recording; transfer probability evaluation pattern can be recorded at paper feed speed of 250
The transfer efficiency was determined using the same evaluation criteria as the transfer probability of 1. Evaluation example 1 15 parts by weight of talc and 2 parts by weight of aluminum sulfate were added to a mixed parip slurry of 80 parts by weight of beaten LBKP and 20 parts by weight of NBKP, and after making paper using a Fourdrinier paper machine in a conventional manner, size pressing was performed using oxidized starch.
I made a base paper of 70g/ ^m2 . 100 parts by weight (solid content) of a slurry of soft calcium carbonate with an average particle size of 0.3 μm was mixed with 10, 15, 20, 30, 40, and 50 parts by weight (solid content) of styrene and butadiene latex solution, and 5 types were prepared. Adjusted the paint.
These paints were applied onto the base paper using an air knife coater at a coating weight of 12 g/m ² on one side, and after drying, they were passed through a super calender to obtain recording sheets 1 to 6. Further, as a comparative example, a paint containing 5 to 60 parts by weight (solid content) of a styrene-butadiene latex solution was prepared, and Comparative Papers 1 and 2 were obtained in the same process as the above-mentioned recording paper. Table 1 shows the coating layer composition and evaluation results of these papers. The base smoothness and average surface roughness of the ink-receiving surface of each paper are also listed. As is clear from Table 1, all of the recording papers according to the present invention exhibit a high transfer probability, and are excellent in transfer characteristics during multiple printing and high-speed recording performance.
In particular, recording paper with a binder ratio (solid content ratio) of 15 to 40 to pigment 100 exhibits excellent characteristics in high resolution and high speed. Comparison paper 1 had a lack of binder, which caused small cracks in the coating layer, deteriorating the resolution characteristics, and comparison paper 2 tended to have poor grip characteristics against feed rollers during paper transport. Ta.

[Table] Evaluation example 2 100 parts by weight of beaten LBKP was used as a pigment pulp, 10 parts by weight of talc and 2 parts by weight of aluminum sulfate were added, paper was made by a conventional method using a Fourdrinier paper machine, and size press was performed using oxidized starch. meter tsubo 50g/
I made a ^m2 base paper. Heavy calcium carbonate with an average particle size of 3μ, average particle size
A styrene-butadiene latex solution, 15 and 30 parts by weight (solid content) of each pigment slurry of 1μ light calcium carbonate, 0.5μ average particle size soft calcium carbonate, and 0.03μ average particle size synthetic silica slurry were added. ) to prepare 8 types of paints. These paints were coated onto the base paper using an air knife coater to give a coated amount of 8 g/m ² on one side, and after drying, they were passed through a super calender to obtain recording papers 1 to 8. In addition, as a comparison column, four types of paints were prepared by mixing 100 parts by weight (solid content) of the slurry of each of the above pigments and 5 parts by weight (solid content) of a styrene-butadiene latex solution, and the comparison paper was prepared in the same manner as in the example. 1 to 4 were obtained.
Table 2 shows the coating layer composition and evaluation results of these papers. The base smoothness and average surface roughness of the ink-receiving surface of each paper are also listed. As is clear from Table 2, even if the type of pigment in the coating layer is changed, any binder with a solid content ratio of 5 to 100 parts of pigment is not suitable for thermal transfer recording paper. Furthermore, recording paper using pigments with a particle weight of 0.5 μm or less showed a high transfer probability and good dot shape. In particular, recording paper using synthetic silica with an average particle size of 0.03 μm as a pigment provided good dot shapes even in high-resolution patterns.

[Table] Evaluation Example 3 An example of a thermal transfer color recording apparatus according to the present invention using the recording paper 7 of Evaluation Example 2 will be described with reference to FIG. A thermal head 53 in which 2624 resistive elements are arranged in one row at 12 elements/mm, a support plate 54 supporting the thermal head 53, and a support plate 54 supporting the thermal head 53.
Ink ribbon peeling roller 5 attached to
A recording head assembly 56 consisting of a spring 57
By the action of an electromagnetic lever 58, the recording head assembly 56 is placed in pressure contact with a silicone rubber roller 59 having a rubber hardness (JIS hardness) of 40°, which is placed opposite the recording head assembly 56 and rotates at a predetermined paper feed speed by a step motor (not shown). It is designed to be able to take either of the following states: A four-color ink ribbon 60 with a width of 210 mm and in which four colors of yellow, magenta, cyan, and black ink appear repeatedly at a pitch of 297 mm in the longitudinal direction is an ink ribbon supply roll 61.
is guided to guide rollers 62 and 63, passes between recording head assembly 56 and platen roller 59, passes through peeling roller 55 and guide roller 64, and then
The ink ribbon is wound onto an ink ribbon take-up roll 65 driven by a motor (not shown). The recording paper 66 is let out from the recording paper supply roll 67 and is fed between the recording paper pressure contact roller 68 and the platen roller 59 in close contact with the circumferential surface of the platen roller 59. Next, the recording operation of the apparatus will be explained. When the start signal is input, the ink ribbon sensor 69 detects yellow ink, and the selected ink is set to the position of the heating element array of the thermal head 53. At this time, the recording head assembly 56
is in a state separated from the platen roller 59, and only the ink ribbon 60 is conveyed by the drive of the ink ribbon take-up roll 65. After that, the recording head assembly 56 is lowered, and the thermal head 5
3. The ink ribbon 60, the recording paper 66, and the platen roller 59 are brought into pressure contact, and the recording preparation is completed. The drive circuit (not shown) of the thermal head 53 is driven by a recording signal corresponding to yellow recording from a recording information source (not shown), and the heating element is driven with a pulse width of 1 ms (maximum), a pulse period of 2 ms, and 70 mJ/mm. Selectively generates heat with the heat energy of ² . Since this thermal head 53 is capable of driving all heating elements, the platen roller 59 rotates 1/12 mm every 2 ms.
The ink ribbon 60 and the recording paper 66 are conveyed one by one without any misalignment. Further, the driving of the thermal head 53 is controlled so that the heat generation temperature of the heating element remains constant regardless of the amount of recording signal. The partially adhered ink ribbon 60 and recording paper 66 are separated by a peeling roller 55, and the ink is transferred to the recording paper. At this time, the ink ribbon 60 is stretched by the drive of the ink ribbon take-up roll 65, which may cause transfer failure.
This prevents 0 flapping. In this way,
First, one screen is recorded using yellow ink. During this time, the ink ribbon 60 and the recording paper 66 are transported at a constant speed. After yellow recording, the recording head assembly 5
6 is separated from the platen roller 59. The recording paper 66 causes a step motor connected to the platen roller 59 to rotate in reverse at double speed. By moving backward the same number of forward steps, the recording paper 66 is set at the initial position. During this time, magenta ink is set on the ink ribbon 60 by driving the ink phone take-up roll 65. After setting the ink ribbon 60 and recording paper 66, the recording head assembly 56 is lowered and the thermal head 53,
The ink ribbon 60, recording paper 66, and platen roller 59 are brought into pressure contact, and preparation for magenta recording is completed. Similar to yellow recording, the thermal head 53 is driven by a recording signal corresponding to magenta recording from a recording information source (not shown), and magenta ink recording is superimposed on yellow recording. Similarly, ion recording and black recording are performed. This recording device created a high-speed color thermal transfer recording device that can output an A4-sized full-color image with a resolution of 12 dots/mm in about 40 seconds. The obtained image is
Since there were no gaps or missing points, the image was an excellent full-color image with excellent gradation and clear dots. On the other hand, in the color thermal transfer recording device configured using Comparative Paper 2 of Example 1 and Comparative Paper 5 of Evaluation Example 2, only a color image with a very rough feel and poor gradation was obtained due to missing image dots. I couldn't help it. Although the embodiments of the present invention have been described above in detail, the present invention is not limited to the above embodiments. For example, the thermal transfer recording method is not particularly limited as long as it uses heat to change the ink on the ink carrier into a state such as melting, fluidization, sublimation, or evaporation. The present invention includes any modifications as long as they do not depart from the spirit of the invention.

[Brief explanation of the drawing]

Figure 1 is a diagram for explaining the problem of image dot formation in thermal transfer recording, Figure 2 is a diagram for explaining the relationship between the surface characteristics of recording paper and ink transfer, and Figure 3 is a diagram for explaining the relationship between the surface characteristics of recording paper and ink transfer.
The figure is a diagram for explaining the structure of a recording paper according to an embodiment of the present invention, FIG. 4 is a diagram showing the structure of a thermal transfer recording apparatus according to an embodiment, and FIG. 5 is a color thermal transfer according to an embodiment. FIG. 1 is a diagram schematically showing a recording device. 31... Base paper, 32... Pigment, 33... Binder, 34... Coating layer, 40... Ink ribbon, 4
3,66... Recording paper, 50... Heat source, 53...
...Thermal head, 59...Platen roller, 6
0...Color ink ribbon.

Claims (1)

[Scope of Claims] 1. A thermal transfer recording paper in which a coating layer consisting of a pigment and a binder is provided as an ink-receiving layer on a base paper, wherein the coating layer has an average particle diameter smaller than 0.5 μm in solid content ratio. 1. A thermal transfer recording paper characterized in that the ratio of binder to 100 parts of pigment is 10 to 50 parts. 2 Pigments with an average particle size of less than 0.5 μm based on solid content
100, the recording paper has a coating layer of binder 10 to 50 on the base paper, and the yellow, magenta,
A thermal transfer recording device comprising an ink carrier carrying ink containing at least cyan, and a heating means for selectively applying heat to the ink carrier.