JPS60110488A - Thermal transfer recording paper and thermal transfer recording apparatus using the same - Google Patents

Abstract

PURPOSE:To enable the certain transfer of ink in performing high speed recording and color recording, by specifying the Beck smoothness and print surface roughness of the ink receiving surface of thermal transfer recording paper. CONSTITUTION:Thermal transfer recording paper is prepared from a paper stock material, wherein a paper strength enhancer of a fixing agent is added to pulp, by a papermaking machine so as to have surface characteristics for imparting Beck smoothness of 300-2,500sec and print surface roughness of 0.6-6mum. In this case, a delivered ink ribbon 50 and the prepared paper 53 are contacted with a platen roller 58 under pressure by an ink ribbon-paper press contacting means 59 constituted of rollers 56, 57 and the platen roller 58. A heating means 60 allows the ink ribbon 50 to contact with the paper 53 under pressure and the ink ribbon 50 after thermal recording is peeled off from the paper 53 at the other point of the roller 57 to perform the transfer of ink.

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 same, and particularly to a thermal transfer recording paper and the same that are excellent in color recording, high-speed recording, and high-resolution recording. The present invention relates to a thermal transfer recording device using.

[Technical background of the invention and its problems]

In recent years, with the development of office automation, there has been a demand for recording devices that can record on plain paper.

A typical example of this is a thermal transfer recording device, which is currently being further developed for color recording, high speed recording, and high resolution recording.

Thermal transfer recording devices perform recording using the simple principle of melting or softening ink with heat and transferring it to recording paper, so they have a simple structure and are maintenance-free. Since image quality is determined by accuracy, it is necessary to perform ink transfer accurately. However, when thermal transfer recording is performed at high speed, or when color recording is performed by overlapping multiple color inks,
As shown in FIG. 1(a), missing pixels occur, or as shown in FIG. 1(b), missing pixels occur.

Furthermore, in high-resolution recording, the clarity of characters is noticeably lacking.

Problems such as color unevenness in color images occur.

It is generally known that in order to solve this problem, the smoothness of the paper should be increased.

In other words, it is said that the smoother the paper, the more efficiently ink is transferred. However, when the present inventor conducted an experiment, it was found that ink transfer to the paper became unreliable when paper had high smoothness.

[Purpose of the invention]

It is an object of the present invention to eliminate the above-mentioned drawbacks and to provide a thermal transfer recording sheet on which ink can be reliably transferred even during high-speed recording and color recording, and a thermal transfer recording apparatus using the same.

[Summary of the invention]

In this invention, % coverage is imposed on the ink-receiving surface of thermal transfer recording paper, with conditions such that Beck smoothness is 300 seconds or more and 2500 or less, and print surf roughness is 06 μ or more and 5 μ or less.

Prior to this invention, as stated in [Technical background of the invention and its problems], the inventor discovered the following based on the fact that when recording paper with high smoothness is used, ink transfer becomes uncertain. I made a similar inference. That is, the transfer of the ink to the paper takes place in the desired transfer area, (1) the ink and the paper come into contact (this is called a contact step), and after the ink is heated (2) the cohesive force of the ink to the paper or the ink is the carrier of the ink. It has a stronger adhesion force than the adhesion force to the film (called the adhesion step), and is achieved by peeling off the paper and the ink ribbon. Improving smoothness is useful for ensuring the contact step, but It is believed that it is not necessarily useful in the deposition step.

When we considered the factors governing this adhesion step, we found that rather than having a smooth surface as shown in FIG. 2(a), we found that the surface of the paper 21 should have an appropriate roughness as shown in FIG. It was concluded that the ink adhesion is improved when the ink has the following properties.

Furthermore, in thermal transfer recording, since recording is performed with the ink carrier and the recording paper in pressure contact, the roughness achieved on the paper surface when under a predetermined suppression is considered to be important. The present invention has been made by paying attention to the above points.

As defined in JISP8119, Bekk smoothness here is defined by the time it takes for a predetermined amount of fluid to flow between a surface to be measured of a predetermined area and an ideal smooth surface, and for all of the fluid to flow out. The unit is seconds. This Beck smoothness indicates the overall smoothness of the paper surface.

On the other hand, print surf roughness indicates the degree of local unevenness of the surface under suppression, and is measured as follows. That is, as shown in FIG. 3, an air inlet 31 adjusted to a low pressure, an air outlet 32 connected to a flow meter (not shown), a measurement head 34 having a partition wall 33 of a predetermined area, and a predetermined Paper 3 between the back support stand 350 hardness
6 is placed so that the ink-receiving surface faces the measuring head 34, and the measuring head 34 and the back support stand 35 support the paper 36.
By applying a constant pressure to the paper and measuring the amount of air leaking from the air inlet 31 to the air outlet 32 through the partition wall 33 for a certain period of time, minute surface roughness on the paper surface under pressure can be detected. This value is called the print surf roughness.

As devices having such means, H and E.

Regular SS old LIMITED P stop■ RPRINT-8 plate F
There is a series of models of (product name). The print surf roughness value of the paper according to the present invention is PARKERPRIN
Measured using T-8 plate FD] 13L750, and the pressure condition was 1960 kP.

〔Effect of the invention〕

According to this invention, the surface not only has high smoothness but also locally has minute irregularities, so that when ink is transferred, the ink and paper come into close contact, and the adhesion between the ink and paper increases. It also becomes stronger.

Therefore, ink transfer is performed more reliably. In particular, the effect is remarkable in high-speed recording and color recording.

Furthermore, high resolution is also achieved.

[Embodiments of the invention]

Next, a thermal transfer recording paper according to the present invention and a thermal transfer recording apparatus using the same will be explained in detail with reference to the drawings.

The thermal transfer recording paper in this example is NBKP, LB
K.P.

Bleached chemical pulps such as NBSP and LBSP alone or mixed pulps with mechanical pulses such as GP, RGP, TMP, semi-chemical pulps, chemical grout pulps, pine resin acid male/compounds, alkyl ketene dimers, synthetic polymers, etc. By adding sizing agents, fillers such as clay, calcium carbonate, white carbon, and talc, paper strength enhancers such as starch, melamine formaldehyde resin, urea form, and aldehyde resin, and fixing agents such as aluminum sulfate, the fourdrinier paper machine Non-coated paper, which is normally manufactured by a paper machine such as, if necessary, externally added with a sizing agent and paper strength agent, and calendered by a supercalender, etc., or a base paper 41 as shown in Fig. 4.
Coated paper is used, which has a coating layer made of pigment 42 and binder 43 on its surface.

The base paper 41 generally includes NBKP, LBKP, NBS
Bleached chemical pulp such as P, LBSP, GP,
Mechanical pulp such as RGP, TMP, semi-chemical pulp, chemical ground pulp, etc., moderately sized, medium-sized paper, wood-free paper, thermoplastic resin film such as polyester or polystyrene, or synthetic paper can be used. However, the composition of the base paper itself is not particularly limited.

It is also possible to use a base paper that has been smoothed using a super calender or the like.

The pigment 42 may be an acicular inorganic pigment such as acicular light calcium carbonate, preferably with an average length of less than 0.5μ, or a powdered urea formaldehyde resin, or a powdered polystyrene resin, which preferably has an average particle size of 0. , granular synthetic resins with an average particle size of less than 5 μm, or synthetic silicas such as natural or white carbon with an average particle size of less than 05 μm, and inorganic pigments such as clay, talc, aluminum sulfate, tyrene dioxide, and zinc oxide, which are preferred. Synthetic silica such as white carbon having an average particle diameter of 0.1 μm or less, and inorganic pigments such as light 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 contained as pigment components in amounts of 30 or more, other pigments with shapes other than those mentioned above can be used. , may be used in combination with pigments of particle size. We also use inorganic pigments such as funnel oil, sodium dodecyl sulfate, organic amines, and metal soaps.

By treating with a nonionic, cationic, or amphoteric surfactant such as sodium likuninsulfonate, the ink ribbon can be used favorably because the wetting of the ink with the ink is improved.

Binder 43B styrene-butadiene rubber (SBR)
, rubber-based materials such as nitrile rubber (NBR), vinyl chloride-
Vinyl acetate copolymer, acrylic resin, methacrylic toilet fat,
Adhesives made from water-insoluble polymers such as urethane resins, vinyl acetate-ethylene copolymers, ethyl cellulose, and petroleum resins, or vegetable waxes such as carnauba wax and book wax, and animal waxes such as beeswax and serratus wax. It is made by using solid waxes such as petroleum waxes such as synthetic waxes, microcrystalline waxes and paraffin waxes, and synthetic waxes such as oxidized waxes and ester waxes. The requirements for the adhesive are film-forming properties and low surface energy, preferably 40 dyn 7 cm or less. The proportion of solid wax to adhesive is between 5 and 50%, preferably between 5 and 25%. This is 5
This is because if the amount is less than 50%, the effect of wax blending will be reduced, and if it is more than 50%, problems will occur in film forming properties.

The ratio of the pigment 42 and the binder 43 forming the first coating layer 34 is 100 parts of the pigment to 50 parts of the binder in terms of solid content. Preferably, the amount is 15 to 40 per 100 of the pigment. The coating liquid forming the coating layer 44 contains various auxiliary agents, a waterproofing agent for the coating layer, a fluidity improving agent during coating, a gloss finishing agent, a preservative, and an antifoaming agent.

You can add dye as needed.

The coating layer is formed using a Tonotsu N coating machine such as a blade coater, air knife coater, roll coater, or bar coater, a size press, a gate roll device, or the like. Furthermore, since the surface of paper with only a coating layer is poor in smoothness and uniformity, the smoothness is adjusted by compressing with super cardan or the like after coating and drying.

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 a print surf roughness of 0.6μ.
more than 5 μ or less, preferably Bekk smoothness of 500 seconds or more 2
000 seconds or less, print surf roughness 0.8μ or more 3
It has surface properties less than μ. This is because when the Bekk smoothness is less than 300 seconds and the print surf roughness is more than 5μ, the contact of the ink to the paper becomes uneven, causing chipping of the image dots, etc.
When the time is 2500 seconds or more and 0.6μ or less, the adhesion of the ink is not enough for a year, 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. 5 shows the basic configuration of the thermal transfer recording apparatus according to the present invention. The ink ribbon 50 is connected to an ink ribbon supply reel 51
The ink ribbon is fed out by the ink ribbon supply row 252. Paper 53 is fed out from a paper supply reel 54 by an ink ribbon supply roller 55 . The unwound ink ribbon 50 and paper 53 are transferred to the ink ribbon-paper pressing means 5, which is composed of rollers 56, 57 and a platen row 258.
9 onto the platen roller 58 via the ink of the ink ribbon (not shown). The ink phone 50 in the press-contact state is heated from the opposite side to which the paper 53 is in contact by a driving circuit (not shown) by a heating means 60 that selectively generates heat temporally and spatially according to recorded information. The heating means 60 is configured to press the ink ribbon 50 and paper 53 together with the flatten roller 58.

After heating recording, the ink ribbon 50 is separated from the paper 53 at the roller 57 by the drive of the ink ribbon discharge roller 61, and the ink is transferred.

The paper 53 is discharged to the outside of the apparatus by a paper discharge roller 62. Through this series of processes, thermal transfer recording is completed. In the case of color printing, the conveyance control of the paper and ink ribbon differs depending on whether the printing is one-sided sequential printing or line sequential printing, but this process is repeated according to the number of colors.

The ink ribbon 50 is made of a resin film of 4 to 20 microns such as polyester, a base film of paper such as condenser paper, solid wax such as carnauba wax or paraffin wax, low molecular weight polyethylene, petroleum resin, etc. with a melting point of 65 to 150'O. Adhesives made of resins that can be easily melted by heat, pigments commonly used in the printing field such as carbon black and phthalocyanine blue, beam materials, and dispersed monoazo dyes and dispersed anthraquinone dyes and anthracene dyes that have a sublimation temperature. An ink that is solid at room temperature with a sublimable dye dispersed at 65-200°C is 2-20°C.
It is applied at a coating amount of g/m'. The form of ink application can be a single color ribbon, a color ink ribbon in which multiple ink layers of different colors for one screen are repeatedly provided in the longitudinal direction, or a color ink ribbon in which ink areas are divided in the longitudinal direction. Yes, ribbon width and length can be determined arbitrarily.

Paper 53 is the paper according to the present invention. It can be used in the form of roll paper, cut paper, etc. As the heating means 60, a moving head type thermal head, a line head type thermal head, a thermal wire, a thermal matrix type character, etc. can be used. The platen roller 58 is preferably made of an elastic material such as silicone rubber so that the thermal head, the ink ribbon, and the paper can be brought into appropriate pressure contact when the platen roller 58 cannot be heated without contact, such as a thermal head. Further, it is preferable that the ink ribbon and the paper move as one between the heating recording point and the peeling point.

Next, the recording results obtained when the above-described apparatus is operated will be described.

Here, we will evaluate the performance of the thermal transfer recording paper according to the present invention.
The following four items were evaluated using an evaluation device that was equipped with a thermal sensor having a heating element density of 12 dots per square meter and a RAD, and recorded images at a resolution of 12 dots per square meter in both the horizontal and vertical directions. Except for 4, recording conditions such as recording voltage and applied pulse width,
The ink ribbons (17, (21, and (41) were black ink ribbons with the same specifications, and (3) were color ink ribbons with the same specifications.

(1) Transfer probability: Arrange pixel dots consisting of 2 dots x 2 dots at a paper feed speed of 2.5 m7, observe the number of dots that are 7/8 or more of the normal pixel size, Total number of observations: 50
The percentage was calculated.

(2) Resolution characteristic A: Checkerboard pattern with side length n is N=1.
2, 3, 4.6 (Resolution 12, 6, 4, 3.2 respectively)
Macbeth Densitometer R
The transfer density was measured in D-2, and the maximum resolution was determined in the area of equal density.

b3) Resolution characteristics 38 Checkerboard pattern with side length n is n-1,
2...(respectively, resolution], 2, 6,...corresponding to dot/home) and record the first color, and after marking the empty part of the checkered pattern with the second color, The dots of the second color were observed under magnification, and the shape of the dots was evaluated in three grades: A, B, and C. A is close to square, B is slightly chipped.
, those with significant chipping were rated C.

(4) High-speed recording performance: Transfer probability evaluation pattern recording was performed at a paper feed speed of 250 cIrL/min, and the transfer probability was determined using the same evaluation criteria as the transfer probability in (1).

[Evaluation Example 1] 15 parts by weight of talc and 2 parts by weight of aluminum sulfate were added to a mixed pulse consisting of 80 parts by weight of beaten LBKP and 20 parts by weight of GP, and paper was made by a conventional method using a Fourdrinier paper machine, and then sized with oxidized starch. Press to produce 50 g/meter tsubo
I made a base paper for Tt. This base paper was passed through a super calender and three types of recording paper (11 to (3)) with a Bekk smoothness of 300 seconds or more and a print surf roughness of 5 μ or less were placed. Commercially available medium-quality paper, high-quality paper with a roughness of 5μ or more,
The gravure papers were designated as comparative papers (1) to (3). Table 1 shows the Beck smoothness, print surf roughness, and evaluation results of these recording papers.

As is clear from Table 1 below, the recording papers (1) to (3) of the present invention exhibit superior suitability as thermal transfer recording papers compared to Comparative Examples (1) to (3).

[Evaluation Example 2] 8 parts by weight of white clay and 2 parts by weight of aluminum sulfate were added to 100 parts by weight of beaten LBKP, and paper was made using a Fourdrinier paper machine in a conventional manner, followed by size pressing with oxidized starch and machine calendering. A base paper of 50 g/m was made. Styrene butadiene latex 15M'Ji
! 1 part (solid content) of light calcium carbonate with an average particle size of 0.1μ and synthetic silica with an average particle size of 0.03μ.
00 parts by weight (solid content) were mixed to prepare two types of paints A and B. These paints are applied onto the base paper using an air knife coater at a coating amount of 8 g/g per side on one side, and after drying, the coated surface has a Peck smoothness of 300 seconds to 2500 seconds and a print surf roughness of 0.6 μ to 5 μ. Super calendar processing is performed to ensure that six types of recording sheets 4 to 9 are created.
I got it. In addition, as a comparative example, a paint was prepared by mixing 8 parts by weight (solid content) of styrene-butadiene latex with 100 parts by weight (solid content) of Sachin Why (with an average particle size of 0.1 μm), and the coating amount on one side was 20 parts by weight on the base paper. g/m using an air knife coater, dried, and then supercalendered, and the coated surface had a Beck smoothness of 2500 seconds or more and a print surf roughness of 0.5μ or less.
4) (5) was obtained. Table 2 shows the Beck smoothness, print surf roughness, and evaluation results of these recording papers and comparative papers.

As is clear from Table 2 of the margins below, even if the surface smoothness of the recording paper is too high, the adhesion of ink will be weakened, and as thermal transfer recording paper, the ink will be transferred by separating the ink ribbon from the recording paper. I know it's not suitable.

In addition, as shown in Tables 1 and 2, surface characteristics (ink-receiving surface characteristics) include Beck smoothness of 500 seconds to 2000 seconds and print surf roughness of 0.8 μ to 3 μ.
The recording paper having the following properties shows particularly excellent ink receptivity, indicating that it is suitable as a recording paper for high-speed recording, high-resolution recording, and color recording.

[Evaluation Example 3] An example of a thermal transfer color recording device according to the present invention using the recording paper 7 of Evaluation Example 2 will be explained with reference to the drawings (Fig. 6).
.

63. Thermal head in which 2624 resistance elements are arranged in one row with 12 elements/+u. ! :Thermal head 63
A recording head assembly 66 consisting of a support plate 64 supporting the ink ribbon and an ink ribbon peeling roller 65 attached to the support plate 64 is disposed opposite to the recording head assembly 66 by the action of a spring 67 and an electromagnetic lever 68. A motor (not shown) allows it to be in contact with or separated from a silicone rubber roller 69 having a rubber hardness (JIS hardness) of 40 degrees rotating at a predetermined paper feeding speed. Width 210mm, yellow in the longitudinal direction,
4-color ink ribbon 70 in which 4-color ink of magenta, cyan, and black appears repeatedly in 297 pitches
is from the ink ribbon supply roll 71 to the guide roller 72.
'13, passes between the recording head assembly 66 and the platen roller 69, passes through the peeling roller 65, and the guide roller 74, and is wound onto the duplex ribbon take-up roll 75 driven by a motor (not shown). taken.

The recording paper 76 is let out from the recording paper supply roll 77 and is fed between the recording paper pressure roller 78 and the platen roller 69 in close contact with the circumferential surface of the platen roller 69.

Next, the recording operation of the apparatus will be explained. Next, the recording operation of the device will be explained. When the start signal is input, the ink ribbon sensor 79 detects yellow ink and sets the ink ribbon so that its tip is positioned at the heat generating element array of the thermal head 63. At this time, the recording head assembly 66 is in a state separated from the platen roller 69, and only the ink ribbon 70 is transported by the drive of the ink ribbon take-up roll 75. After that, the recording head assembly 66 is lowered, and the thermal head 63 and ink ribbon 7 are lowered.
0, the recording paper 76 and the grating roller 69 are brought into pressure contact, and the recording preparation is completed. Recorded information source (not shown)
The drive circuit (not shown) of the thermal head 63 is driven by the recording signal corresponding to the yellow recording, and the heating element has a pulse width of 1 ms (maximum), a pulse period of 2 ms, and a pulse frequency of 70 mm.
It selectively generates heat with an exothermic energy of mJ/M. Since this thermal head 63 is capable of driving all heating elements, the ink ribbon 70 and the recording paper 76 are conveyed by 1/12 every 2 ms without shifting due to the rotation of the platen roller 69. Further, the driving of the thermal head 63 is controlled so that the heat generation temperature of the heating element remains constant regardless of the amount of distributed signals. The partially adhered ink ribbon 70 and recording paper 76 are separated by a peeling roller 65, and the ink is transferred to the recording paper. At this time, ink ribbon 70
is stretched by the drive of the ink ribbon take-up roll 75 to prevent flapping of the ink ribbon 70, which causes folding and poor transfer. In this way, one screen is first recorded using yellow ink. During this time, the ink ribbon 70 and the recording paper 76 are transported at a constant speed.

'After the yellow recording is completed, the recording head assembly 76 is separated from the platen roller 69. The recording paper 76 causes a step motor connected to the platen roller 69 to rotate in reverse at double speed. By moving the recording paper 76 backward by the same number of forward steps, the recording paper 76 is set at the initial position. During this time, magenta ink is set on the ink ribbon 70 by driving the ink ribbon take-up roll 75. After the ink ribbon 70 and recording paper 760 have been set, the recording head assembly 66 is lowered and the thermal head 63, ink ribbon 70, recording paper 76, and platen roller 69 are brought into pressure contact again, completing magenta recording preparation. Similar to yellow recording, the thermal head 63 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, cyan recording and black recording are performed.

Here, the ink transfer state in the example will be further described in a false manner. Figure 7 shows l[i! First color ink 8 on recording paper 76
This shows a state where the second color ink 82 is about to be transferred after the transfer of 0 is completed. Since the recording of the first color has been completed, there is a spot pressure of the ink 80 on the recording paper 76. Here, for example, if a second color ink 82 is to be transferred between the first color ink 80, the object to be transferred is a composite of the recording paper 76 and the ink 80, The surface has larger irregularities than the surface of the recording paper 76 alone.

Naturally, if this ink 82 is used, the state of contact between the ink 80 and the recording paper 76 is not favorable, and the ink 82 is pressed against the recording paper 76 with a weaker pressure. However, if the print surf roughness of the recording paper 76 is an appropriate value, the ink 82 and the recording paper 76 will be compatible and wet, and even with a weak pressure, the recording paper 76 and the ink 82 will be more reliably connected. For close contact. This is the mechanism for improving image quality.

With this recording device, A with a resolution of 12 dots)/ig
A high-speed color thermal transfer recording device that can output four-size pull-color images in about 40 seconds has been created. The obtained image was an excellent full-color image with extremely good gradation and clear dots since there were no missing or missing dots.

In the color thermal transfer recording device configured using Comparative Paper 2 of Evaluation 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. Ta.

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.

In this way, any modification is included in the invention as long as it does not depart from the spirit of the invention.

[Brief explanation of drawings]

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 print surf roughness measuring means. FIG. 4 is an explanatory diagram for explaining the structure of a recording paper according to an embodiment of the present invention. FIGS. The figure shown in FIG. 7 is a schematic diagram for explaining ink transfer during color recording. 21.76...Paper, 22,80.82...Ink, 41...Base paper, 42...Pigment, 43...Binder, 44...Coating layer, 40...Ink ribbon, 53
．． 76... Recording paper, 60... Heat source, 63...
Thermal head, 58.69...Platen roller, 7
0...Color ink ribbon. Agent: Patent Attorney Noriyuki Chika (and 1 other person) -～

Claims (2)

[Claims] (1) A thermal transfer recording paper having an ink receiving surface having a Beck smoothness of 300 seconds or more and 2500 seconds or less, and a print surf roughness of 0.6 μm or more and 5 μm or less. (2) A recording paper having an ink-receiving surface with a Beck smoothness of 300 seconds or more and 2500 seconds or less and a print surf roughness of 0.6 μ or more and 5 μ or less, and an ink carrier carrying ink to be transferred to this recording paper. , and heating means for selectively applying heat to the ink carrier.