JPS63193886A - Thermal transfer recording medium - Google Patents

Abstract

PURPOSE:To realize a high-quality printing even on low-surface smoothness paper to be subjected to transfer, by a method wherein, at lest one release layer and at least one heat softening layer are formed on a substrate, and the elongation at break of the heat softening layer is limited to be within a specific range. CONSTITUTION:On a substrate, at least one release layer and at least one heat softening layer are formed, and the elongation at break of at least one of the heat softening layers is set to be within the range of 70-200% at a temperature of 27 deg.C. The heat softening layer is formed by aqueous coating. With the elongation at break determined as the above, the thermal transfer layer is transferred to a paper to be subjected transfer uniformly in thickness due to the reduction of the void volume, and the fixing properties of the thermal transfer layer to the paper to be subjected transfer is enhanced. Therefore, a printing can be conducted in a high quality even on a low-surface smoothness transfer paper.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a thermal transfer recording medium. For more details,
The present invention relates to a thermal transfer recording medium that can form high-quality prints even on transfer media with low surface smoothness.

[Prior art] basically has a structure in which a heat-melt ink layer made of a heat-melt material with a colorant dispersed thereon is formed on a sheet-like support, and this heat-sensitive transfer recording medium The ink layer of 1B is stacked on a transfer medium (generally paper) and heated by a thermal head from the support side of the thermal transfer recording medium, and the molten ink layer is transferred to the transfer medium, depending on the heating area. It forms an ink image.

It is possible to perform good printing on a highly smooth transfer medium using a thermal transfer recording medium, but the problem is that when a transfer medium with low smoothness is used, the print quality deteriorates significantly. be.

This problem is particularly problematic when using paper, which is the most widely used transfer medium. That is, paper with high smoothness is rather special, and ordinary paper has considerable irregularities due to the entanglement of fibers. For example, in rough vapor with Bekk smoothness of about 10 seconds,
From the top of the convex part, there are many parts where the four parts are the deepest or more than 100m deep.

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When printing is performed using Ik6-Inh, the print density may be low or part of the print may be missing, making it impossible to print with high quality.

On the other hand, Ii! In order to improve the printing quality on transfer paper with low surface smoothness of thermal transfer recording media, a method has been adopted in which a layer called a release layer is interposed between the ink layer and the support (Japanese Patent Application Laid-Open No. 59-1991). -224: l'12, same 60
-97888, 60-187593, 60-1
(See publications such as No. 8:1192 and No. 60-185488).

However, according to studies conducted by the present inventors, it has been found that even if these thermal transfer recording media having a multilayer structure are used, it is not possible to provide good print quality on rough paper.

That is, since the invention described in the above-mentioned publications has a multilayer structure, the structure of the ink layer itself is based on the same idea as that of a single layer structure, and the release layer etc. Although the releasability of the ink layer may be improved by passing the ink layer through the rough surface, the fixation of the ink layer to the rough surface is no different from that of a conventional single layer. Alternatively, it adheres only in the vicinity thereof, and as a result, the void rate of the layer to be transferred becomes high, making it impossible to print with good TLF quality on rough paper.

[Purpose of the invention] This invention has been made based on the above circumstances.

That is, an object of the present invention is to provide a thermal transfer recording medium that can realize high-quality printing not only on transfer paper with excellent surface smoothness but also on transfer paper with poor surface smoothness. The goal is to provide the following.

[Means for achieving the above object 1] The structure of the present invention for achieving the above object is such that at least one release layer and one heat-softening layer are provided on a support, and the heat-softening layer is The thermal transfer recording medium is characterized in that the elongation at break of at least one layer at 27° C. is within the range of 70 to 200%.

As a result of studying the characteristics of the ink layer necessary for good printing on rough paper, the inventor found that the peelability of the ink layer from the support and the elongation at break of the ink layer affect the compatibility with rough vapor. We found that this is an important factor that increases the

Therefore, the thermal transfer recording medium of the present invention can be used on a support! 121 layer and at least one thermosoftening layer,
And the elongation at break of the thermosoftening layer is within a specific range.

It is desirable that the support for the thermal transfer recording medium of the present invention has heat-resistant strength, high dimensional stability, and high surface smoothness.

Examples of such materials include paper such as transparent paper, condenser paper, laminated paper, coated paper, resin films such as polyethylene, polyethylene terephthalate, polystyrene, polypropylene, and polyimide, composites of paper and resin films, and aluminum. Metal sheets such as foils or the like are preferably used.

In order to obtain good thermal conductivity, the thickness of the support is preferably within the range of 155 to 15 gm.

Further, in the present invention, the structure of the back surface of the support is arbitrary, and the support may have a backing layer for the purpose of preventing states kink or the like.

At least one layer on this support! A has delamination. Two or more release layers can be coated on the support, but
In the present invention, it is preferable that there is only one release layer.

This release layer usually contains a heat-melting substance and a thermoplastic resin, and is a layer in which the properties of the heat-melting substance are dominant, and mainly contains a heat-melting layer and a support. This layer has the function of measuring the adhesive strength of the adhesive.

Common heat-melting substances and thermoplastic resins can be used. Furthermore, it is preferable to use a thermofusible substance and a thermoplastic resin that are used when producing the thermosoftening layer 31, which will be described later.

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150° C.) is preferably used, and as the thermoplastic resin, it is preferable to use an ethylene-vinyl acetate copolymer.

The content of the heat-fusible substance in the release layer is usually 50% by weight or more (preferably 50 to 7g) based on the total weight of the thermoplastic resin and the heat-fusible S material forming this layer. %
(within the range).

This release layer may contain a colorant, but
Basically, it is preferable to include a colorant in the heat-softening layer described below.

In addition, the release layer may contain polyoxyethylene button-containing compounds, inorganic or organic fine particles (metal powder, silica gel, etc.)
, oils (linseed oil, mineral oil, etc.) may also be added.

The thickness of the release layer is usually 0.5 to 4 μm, preferably 1.0 to 2.5 μm.

The viscosity of the release layer at 100°C is 2 to 1000 cps
The amount of each component and the type of component should be adjusted so that it falls within the following range.

It is particularly preferable to apply the 216 layers by employing a hot melt coating method.

The hot melt coating method is a coating method in which the components constituting this layer are mixed and the resulting mixture is melted and coated. In this case, the heating temperature should be such that the heat-fusible substance, which is the main component forming this layer, is in a molten state. Usually, it is 150° C. or lower. The molten component can be applied using a known method such as the coating i9 method using a wire spar.

In addition to hot-melt coating, this release layer can also be prepared by dissolving or dispersing the components forming this layer in an organic solvent to prepare an organic solvent solution and applying this. Prepare an aqueous emulsion of the ingredients to make this? It can also be prepared by Iri.

1 east to 1 The heat-sensitive transfer recording medium of the present invention is provided with at least one heat-softening layer on the above-mentioned release layer.

In the present invention, the elongation at break of at least one of the heat-softening layers at 27° C. is within the range of 70 to 200%.

By setting the elongation at break of the thermosoftening layer within the above range,
A uniform heat-softening layer is formed between the convex portions on the surface of the transfer paper, making it possible to print with good quality on the transfer paper with low surface smoothness. Become. Therefore, if the elongation at break is lower than 70%, the heat-softening layer will be cut between the convex parts on the surface of the transfer paper, resulting in an increase in the void rate, and the printed characters will have insufficient print density. Part of the image is missing, resulting in poor print quality. On the other hand, if the elongation at break is higher than 200%, the cohesive force of the thermosoftening layer becomes higher than necessary, and as a result, the printed characters lack edge sharpness and also induce a whisker-like stringing phenomenon.

In addition, when it has two or more heat-softening layers, it is preferable that the elongation at break of at least the outermost heat-softening layer is within the above range, and is preferable for all types of heat.

An example of a method for adjusting the elongation at break of the heat-softening layer within the above range is a method of adjusting the types of thermoplastic resin and heat-melting Th substance, their blending ratios, and the like.

This thermo-softening layer is a layer whose main components are a thermoplastic resin and a thermo-softening substance, but unlike the above-mentioned release layer, the properties of the thermoplastic resin among these components are dominant. It is a layer. Therefore, in order to ensure that the degree of stretching of this layer is within the above-mentioned range and to ensure that the colorant is well fixed on the transfer medium, the thermoplastic resin and thermosoftening material that form this layer must be adjusted. The content of the thermoplastic resin is 50% by weight or more (preferably 60 to 97% by weight) based on the total weight.
(% by weight).

The thickness of this thermosoftening layer is usually 0.5 to 5.0 μm.
is within the range of In particular, it is preferable that the dry thickness is within the range of 1.0 to 4.0 pm.

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It is preferable that the roundness is within the range of 400 to 8000 cps at mt-t-too °C, and the type and amount of the heat-melting substance and thermoplastic resin used are adjusted so that the roundness is within this range. Is it good to specify?

The heat-melting substance used here has a melting point (Yanagimoto MPJ-2
It is preferably a solid or semi-solid material with a temperature of 40 to 150°C (measured by mold).

Specific examples include vegetable waxes such as carnauba wax, wood wax, auriculie wax, and Nispar wax; animal waxes such as beeswax, insect wax, shellac wax, and spermaceti wax; paraffin wax, microcrystalline wax, polyethylene wax, ester wax, and Petroleum waxes such as acid waxes, mineral waxes such as montan wax, osikerite, and ceresin, and other waxes.

Higher fatty acids such as valmitic acid, stearic acid, margaric acid and behenic acid, higher alcohols such as valmityl alcohol, stearyl alcohol, behenyl alcohol, marganyl alcohol, myricyl alcohol and eicosanol, cetyl palmitate, myricyl valmitate, cetyl stearate and higher fatty acid esters such as myricyl stearate.

Amides such as acetamide, propionic acid amide, valmitic acid amide, stearic acid amide and amide wax, and higher amines such as stearylamine, behenylamine and palmitylamine may be mentioned, and these may be used alone. It may be used in combination.

In the present invention, among these heat-melting substances, waxes having a melting point of 40-tso''c can be suitably used.

Examples of thermoplastic resins include polyamide resins, polyester resins, polyurethane resins, polyolefin resins, acrylic resins, vinyl chloride resins, cellulose resins, rosin resins, ionomer resins, and petroleum resins. kind.

Natural rubber, elastomers such as styrene-butadiene rubber, isoprene rubber, and chloroprene rubber; rosin derivatives such as ester gum, rosin maleic acid resin, rosin phenolic resin, and hydrogenated rosin; and phenolic resins, terpene resins, and cyclopentadiene resins. and aromatic hydrocarbon resins with a softening point of 50 to 150
C. high molecular compounds, etc. can be mentioned.

Among these, preferred thermoplastic resins include acrylic resins.

Acrylic resins can be obtained, for example, by emulsion polymerization of monobasic carboxylic acids such as acrylic acid and methacrylic acid or their esters, and at least one type of heptamer copolymerizable with these. The carboxylic acid salt used in this case is (meth)acrylic acid methyl ester.

(meth)acrylic acid ethyl ester, (meth)alic acid butyl ester, (meth)acrylic acid isobutyl ester, (meth)acrylic acid amyl ester, (meth)acrylic acid hexyl ester, (meth)acrylic acid octyl ester, (meth)acrylic acid octyl ester, ) Acrylic acid 2-ethylhexyl ester, (meth)acrylic acid decyl ester, (meth)acrylic acid dodecyl ester, (meth)acrylic acid hydroxyethyl ester, (meth)acrylic acid hydroxyethyl ester, and the like. Examples of heptamers that can be copolymerized include vinyl acetate, vinyl chloride, vinylidene chloride, maleic anhydride, fumaric anhydride, styrene, 2-
Methylstyrene, chlorstyrene, acrylonitrile,
Vinyltoluene, N-methylolacrylamide, N-
Methylolmethacrylamide, N-butoxymethylacrylamide, N-butoxymethacrylamide, vinylpyridine, N-vinylpyrrolidone, and the like may be mentioned, and one or more of these may be selected.

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Mar can also be suitably used. Specific examples include emulsion polymers of diene monomers such as butadiene, isoprene, isobutylene, and chlorobrene, and the above-mentioned copolymerizable monomers. Examples include styrene polymers, butadiene-styrene-vinylpyridine polymers, butadiene-acrylonitrile polymers, chlorobrene-styrene polymers, and chloroprene-acrylonitrile polymers.

Further, preferred polymers include ethylene copolymers. For example, ethylene-vinyl acetate copolymer, ethylene-ethyl acrylate copolymer, ethylene-methyl methacrylate copolymer, ethylene-isobutyl acrylate copolymer, ethylene-acrylic acid copolymer, ethylene-vinyl alcohol copolymer. Polymer, ethylene-
These include vinyl chloride copolymers and ethylene-acrylic acid metal salt copolymers.

This heat-softening layer usually contains a colorant. As the colorant, commonly used pigments and dyes such as inorganic pigments and organic pigments can be used.

Examples of the inorganic pigments include titanium dioxide, carbon black, zinc oxide, Prussian blue, cadmium sulfide, iron oxide and chromates of lead, zinc, barium and calcium. Examples of the organic pigments include azo-based, thioindigo-based, anthraquinone-based, anthurone-based, triphenedioxazine-based pigments,
These include hat dye pigments, phthalocyanine pigments such as copper phthalocyanine and its derivatives, and quinacridone pigments.

Examples of organic dyes include acid dyes, direct dyes, disperse dyes, oil-soluble dyes, and metal-containing oil-soluble dyes.

In the heat-softening layer, the colorant is present in a conventional range (e.g., 5 to 35% by weight, based on the total weight of the heat-melt material and heat-soften material in this layer), preferably 5 to 28%. (% by weight).

Preferably, the above-mentioned heat-softening layer is formed by preparing an aqueous emulsion containing a thermo-UT plastic resin and a heat-softening substance, and applying the same.

This aqueous emulsion can be prepared by preparing a mixture of a thermosoftening substance and a thermoplastic resin, and emulsifying this mixture according to known methods. Alternatively, it can also be prepared by mixing aqueous emulsions obtained by individually emulsifying the above-mentioned thermosoftening substance and thermoplastic resin.

For example, aqueous emulsions of hot-melt materials and thermoplastic resins can be prepared by emulsifying them in water using existing methods such as phase inversion, high-pressure emulsification, and ultrasonic dispersion using emulsifier-containing systems. Something will happen. As the emulsifier, any of nonionic emulsifiers, anionic emulsifiers, cationic emulsifiers, and amphoteric emulsifiers can be used.

This aqueous emulsion may contain a fluorosurfactant in addition to the emulsifier. Fuji 1: 5.
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The effect of effectively preventing the phenomenon of r+ I r*, , Ec-/ is improved.

The content of the fluorine-based surfactant in this layer is preferably 0.05 to 3% by weight based on the total solid content of the heat-softening layer.

This aqueous emulsion may also contain thickeners, such as sodium polyacrylate, to adjust the viscosity.
It may contain a substance that improves surface slipperiness, such as colloidal silica. The pond water emulsion has
A water-soluble polymer may be added to the aqueous phase.

For example, representative examples of water-soluble polymers include polyvinylpyrrolidone, polyvinyl alcohol, water-soluble polyurethane, water-soluble acrylic, water-soluble polyester, and water-soluble polyamide.

There is no particular limitation on the coating method for coating at least one layer of the aqueous emulsion thus prepared on the above-mentioned release layer, and any known method such as a method using a wire bar or the like may be employed.

In addition, when there are two heat-softening layers, it is preferable that at least one layer is coated with water-based coating, and it is particularly preferable that the outermost heat-softening layer is coated with water-based coating. In the present invention, it is particularly preferable that the completely softenable layer be applied in an aqueous manner.

For example, by aqueous coating using an aqueous emulsion, the particles of the components constituting the aqueous emulsion form a heat-softening layer while maintaining their particle state to some extent,
This improves the '2+ quality of printing on transfer media with low surface smoothness.

- Others The thermal transfer recording medium of the present invention is not particularly limited in its planar shape, and may be used, for example, in the form of a typewriter ribbon or a wide tape used in line printers.

Further, for color recording, a heat-sensitive transfer recording medium can be provided in which a peeling layer or a heat-softening layer containing coloring materials of several different tones is coated separately in stripes or blocks.

The thermal transfer method using this thermal transfer recording medium is not different from a normal thermal transfer recording method, but will be explained using the most typical thermal head as an example.

That is, the heat-softening layer of the heat-sensitive transfer recording medium and a recording medium such as transfer paper are brought into close contact with each other, and if necessary, heat pulses are further applied by a platen from the back side of the transfer paper, and heat pulses are applied by a thermal head. The Afs layer and the thermosoftening layer are locally heated depending on the desired printing or transfer pattern. When the temperature of the 8 parts of the release layer and the heat-softening layer exceeds 11 L/L, the release layer and the heat-softening layer quickly soften, and the softened heat-softening layer is transferred to the surface of the recording medium.

[Effects of the Invention] According to the present invention, at least one release layer and one heat-softening layer are formed on the support L, and the elongation at break of at least one heat-softening layer at 27°C is When it is 70% or more and 200% or less, the void ratio decreases to 1.
8! The thermal transfer layer transfers to the transfer paper with a uniform thickness, and the fixability of the heat-sensitive transfer layer to the transfer paper is improved.

Therefore, according to the present invention, it is possible to provide a heat-sensitive recording medium that can print with high quality not only on transfer paper with high surface smoothness but also on transfer paper with low surface smoothness.

[Examples] Hereinafter, Examples and Comparative Examples of the present invention will be given, but the present invention is not limited thereto.

Note that "parts" used below indicate "parts by weight."

(Comparative Example 1) The following release layer coating set 1 & material was applied to a film thickness of 2.07 parts m on a polyethylene terephthalate film with a thickness of 3.5 JLm.
A hot melt coating was applied to form layers ' and A#.

Paraffin wax: 90 parts Ethylene-vinyl acetate copolymer: 10 parts Next, apply the heat-softening layer coating composition shown below. Using a wire bar, the film thickness was adjusted to 2 gm! IS layer rr11-1-4 + hair piece light 1 wire, 1 min.

H-・Right Acrylic water-based emulsion: 75 parts Carbon flag wood dispersion: 25 parts (The expression "~ parts" in the water-based emulsion above refers to the active ingredient in the emulsion. Weight.The same applies hereinafter to the present invention.

) The relationship between the temperature and elongation at break of the heat-softening layer of this heat-sensitive transfer recording medium was measured. Note that the elongation at break of the thermosoftening layer at 27°C was 240%.

The results are shown in Figure 1.

Note that the elongation at break in the present invention was measured as follows.

Measuring equipment Fudo Rheometer (Fudou Kogyo■
(manufactured by) Measurement sample Width 20cm-1 Thickness 0.2~20mm
1 grip interval 20-Peng Tensile speed 100 mm/min Δ Constant temperature and humidity 27° C. Q (printing) was performed on rough vapor (Lancaster bond paper, Beck smoothness: 2 seconds) using a printing speed of 20 characters per second, and the print quality was evaluated.

There was no bleeding or smudging, but there were some prints that were stringy and lacked edge sharpness.

(Example 1) A heat-sensitive transfer recording medium was produced in the same manner except that instead of the heat-softening columnar layer coating composition used in Comparative Example 1, the heat-softening layer coating set Jf shown below was used.

- Acrylic water-based emulsion: 35 parts Rosin water-based emulsion: 30 parts Paraffin water-based emulsion (emulsion made by emulsifying paraffin straw "cus" with a melting point of 70°C in water)...10 Part carbon black aqueous dispersion...25 parts For this thermal transfer recording medium,
When the relationship between temperature and elongation at break was measured in the same manner as in Comparative Example 1, the elongation at break of the thermosoftening layer at 27°C was 1.
It was 80%.

The results are shown in Figure 1.

Next, when the print quality was evaluated in the same manner as in Example 1 using the obtained thermal transfer recording medium, there was no fading, bleeding,
Clear prints with little background smudge were obtained.

(Example 2) A heat-sensitive transfer recording medium was produced in the same manner except that the heat-softening columnar layer coating composition shown below was used instead of the heat-softening columnar layer coating composition used in Comparative Example 1.

, l Ethylene-vinyl acetate copolymer aqueous emulsion...25 parts Acrylic aqueous emulsion...20 parts Paraffin aqueous emulsion (paraffin wax with a melting point of 70°C is emulsified in water) Emulsion)...30 parts Carbon black aqueous dispersion...25i For this thermal transfer recording medium,
When the relationship between temperature and elongation at break was measured in the same manner as in Comparative Example 1, the elongation at break of the heat-softening layer at 27°C was 7.
It was 5%.

The results are shown in Figure 1.

Next, when the print quality was evaluated in the same manner as in Example 1 using the obtained thermal transfer recording medium, there was no fading, bleeding,
Clear print with little background smudge was obtained.

(Comparative Example 2) A heat-sensitive transfer recording medium was produced in the same manner as in Comparative Example 1, except that the heat-softening coating composition shown below was used instead of the heat-softening columnar layer coating composition used in Comparative Example 1.

“W Acrylic water-based emulsion [trade name [Boncourt 3226 J]]...225 parts Rosin water-based emulsion...10 parts Paraffin water-based emulsion (emulsion made by emulsifying paraffin wax with a melting point of 70°C in water)...・・40 parts 91- →I-no →
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When the relationship between temperature and elongation at break was measured for 610, Fqp Jakuko's thermal transfer recording medium in the same manner as in Comparative Example 1, the elongation at break of the thermosoftening layer at 27°C was 44%. .

The results are shown in Figure 1.

Next, the print quality was evaluated in the same manner as in Example 1 using the obtained thermal transfer recording medium.

Fading, blurring, and scumming occurred, and clear printing could not be obtained.

(Example 3) A heat-sensitive transfer recording medium was produced in the same manner except that the heat-softening columnar layer coating composition shown below was used instead of the heat-softening columnar layer coating composition used in Comparative Example 1.

-1 Acrylic water-based emulsion...15 parts Water-soluble polyester resin...15 parts Acrylic water-based emulsion...20 parts Carnauba wax water-based emulsion...l0fi terpene resin water-based emulsion...
...25 parts carbon black aqueous dispersion...2
5 parts When the relationship between temperature and elongation at break was measured for this thermal transfer recording medium in the same manner as in Comparative Example 1, it was found to be 27°C.
The elongation at break of the heat-softening layer was 110%.

The results are shown in Figure 1.

Next, when the print quality was evaluated in the same manner as in Example 1 using the obtained thermal transfer recording medium, there was no fading, bleeding,
A #V bright print with little background smudge was obtained.

As mentioned above, the elongation at break of the thermosoftening layer at 27°C is 7
Good printing can be performed when the ratio is within the range of 0 to 200%.

The cohesive force at 20°C is 180 kg/crn' at the maximum for the heat-softening layer of Comparative Example 1, and the cohesive force of the heat-softening layer for Example 1 is 100 kg/crn', for the heat-softening layer of Example 2. The cohesive force of the sexual layer was 80 kg/cm'. From these results, it is clear that the printability on transfer media with low surface smoothness is influenced more by the elongation at break than by the cohesive force of the thermosoftening layer.

Furthermore, according to the inventor's simulations based on infrared microscope data, under the printing conditions of the thermal transfer printer that is currently most widely used,
The peeling temperature of the heat-softening layer is a little less than 30°C (more precisely, usually 27'C), and this has a significant effect on the elongation at break of the heat-softening layer at 27°C and on the printing quality. Correlates with

That is, in order to print without creating voids on the rough paper, the heat-softening layer and its physical properties when released from the support are very important.

Particularly when a thermal transfer printer is used, due to its principle, the heat-softening layer that has been heated to a softened state separates from the release layer before being cooled to room temperature. Therefore, it can be seen that the elongation at break of the thermosoftening layer at the temperature at which it is peeled off is the most important factor.

[Brief explanation of the drawing]

FIG. 1 is a graph showing the relationship between temperature and elongation at break in the heat-softening layer constituting this heat-sensitive transfer recording medium.

Claims (2)

[Claims] (1) At least one release layer and one heat-softening layer are provided on the support, and the elongation at break of at least one of the heat-softening layers at 27°C is within the range of 70 to 200%. A thermal transfer recording medium characterized by the following. (2) The heat-sensitive transfer recording medium according to claim 1, wherein the heat-softening layer is formed by water-based coating.