JPH04189190A - Thermal transfer sheet - 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 [Industrial Application Field] The present invention relates to a heat-sensitive transfer sheet, and particularly to a heat-sensitive transfer sheet that has good transportability and can produce high-quality images.

[Conventional technology]

In recent years, the thermal transfer recording method using a thermal head has been used for many advantages such as being noiseless, the device being relatively inexpensive and compact, easy to maintain, and stable printed images. It looks like this. The heat-sensitive transfer sheet used in such a heat-sensitive transfer recording method is made by mixing or laminating wax such as natural wax or synthetic wax, coloring agent, thermoplastic resin, etc. on one side of a support such as a polyester film. , a heat-sensitive transfer layer (heat-melting ink layer) is provided.

However, such a heat-sensitive transfer sheet has the disadvantage of poor conveyance properties and poor heat resistance at the contact surface with the thermal head. Therefore, in order to impart smoothness and heat resistance to the contact surface with the thermal head, it has been proposed to provide a back layer made of a heat-resistant and slippery material on the back surface of the support of the heat-sensitive transfer sheet. For example, special public show 5g-1
No. 3359 discloses that a heat-resistant protective film made of silicone resin with a thickness of 0.5 to 5 μm is dried at 150 to 200° C. and provided as a back layer, as described in Japanese Patent Application Laid-Open No. 62-33682 and Japanese Patent Application Laid-Open No. 62-62. No. 109688 further discloses that a back layer of a silicone rubber thin film is provided, as disclosed in JP-A-1-1-1.
41789 discloses providing a back layer of condensed silicone comb. In addition, from 1987 onwards
Japanese Patent No. 196293 discloses a method of supplying oil to a thermal head or the back surface of a thermal transfer sheet (ribbon) during printing.

[Problem to be solved by the invention]

However, although such heat-sensitive transfer sheets that have been proposed so far have the effect of improving slipperiness and heat resistance to some extent, they are still not satisfactory. For example, silicone resin has a low heating loss property of about 5% up to 550°C, making it an excellent heat-resistant protective film, but if you try to prevent sticking by imparting heat resistance to the hack layer, The thinner the coating film, the lower the heat resistance effect.
As described in Japanese Patent Publication No. 58-13359, a thickness of 0.5 μm or more is required. However, as the coating thickness increases, a problem arises in that the sensitivity deteriorates.

In addition, since silicone resin has heat resistance through network three-dimensional crosslinking using trifunctional siloxane bonds, it is necessary to have a high crosslinking density. It decreases due to loss of liquidity. When the coating thickness is increased to increase heat resistance,
The fluidity within the layer is further reduced, and the slipperiness is significantly reduced.

In order to improve image quality, modern high-speed printers have made the platen roll harder and the pressure of the presser foot stronger. However, since the ribbon is strongly sandwiched between hard objects, the ribbon transportability is poor and sticking is a problem. It is easy to wake up, and at high energy, the ribbon will break. Furthermore, due to the high crosslinking, the coating becomes hard and the head is easily worn. In addition, heating at high temperature and for a long time is necessary to obtain crosslinking, which may cause the support film to shrink or require reheating, which may deteriorate the image or be unproductive.

Furthermore, thermal transfer sheets with a back layer of a thin silicone rubber film have weak binding strength between the support film and the back layer.
There is a problem that the guide roll that comes into contact with the back surface gets dirty and tends to meander during coating production, and heat-sensitive transfer sheets with a back layer of condensed silicone rubber generate water, so drying energy is required. There is a problem that
Accordingly, an object of the present invention is to provide a thermal transfer recording notebook that has good sliding properties, good transportability, has a thin coating film, has little thermal history of the support film, and can produce images of good quality. It is in.

[Means for Solving the Problems] According to the present invention, in a heat-sensitive transfer sheet in which a heat-sensitive transfer layer is provided on the surface of a support and a back layer is provided on the back surface of the support, the back layer is made of silicone rubber. It is made of a mixture with acrylic resin and has a coating thickness of 0.00.
A thermal transfer sheet characterized in that the thickness is 1-0.1 μm is provided.

That is, the heat-sensitive transfer sheet of the present invention has a coating thickness of 0.001-
〇.A back layer made of a silicone rubber/acrylic resin mixture of 1 μm is provided, and because of the above structure, it has good sliding properties, good conveyance, and has low thermal history and can produce images of good quality. It will be what you get.

Next, the present invention will be explained with reference to the drawings.The specific structure and operation of the present invention are as follows.

In FIG. 1, the thermal transfer sheet of the present invention includes a support 1,
It is composed of a heat-sensitive transfer layer (ink layer) 2 and a back layer 3. That is, the thermal transfer layer 2 is provided on the surface of the support 1, and the back layer 3 is further provided on the back surface of the support 1. During transfer, a thermal head 4 is used to transfer the heat from the surface of the back layer 3. When heated, part of the ink in the heat-sensitive transfer layer 2 is melted and peeled off, and transferred to the recording paper. In addition, 1g
The thermal transfer layer 2 may have a single layer structure or a laminated structure. Furthermore, as shown in FIG. 2, a release layer 5 may be provided between the support 1 and the heat-sensitive transfer layer 2.

In the present invention, a coating film made of a mixture of silicone rubber and acrylic resin is coated on the back surface of the support with a thickness of 0.00j to 0.1
A back layer of .mu.m is provided. Unlike silicone resin, which is trifunctional, silicone rubber is difunctional and is made by addition polymerization of vinyl groups partially substituted with alkyl groups, resulting in a crosslinked product with rubber elasticity. say. A characteristic of silicone rubber is that its crosslinking density is overwhelmingly lower than that of silicone resin, so it has many linear alkylsiloxane bonds, so it has high interlaminar fluidity, and when made into a thin film of 0.1 μm or less. can form a slippery coating film.

In order to cure silicone rubber, a platinum-based material such as chloroplatinic acid is mainly used to add-polymerize the vinyl groups introduced to spread the bifunctional, linearly connected polyalkylsiloxane into a planar shape. It is sufficient to use a prepared catalyst. However, since the back layer of the present invention is a thin film, it has little transferability to the ink surface, so it is not necessarily necessary to cure it in consideration of thermal history.

On the other hand, acrylic resin has excellent binding properties with a support film (for example, a polyester film) and also has excellent compatibility with silicone rubber. As acrylic resin,
Those having a glass transition temperature (Tg) of 45° C. or higher are preferable because they have a high roll stain prevention effect. Specific examples of acrylic resins include the following. Note that the number in parentheses indicates Tg.

Polymethyl methacrylate (105°C), polyethyl methacrylate (62°C), polyisopropyl, methacrylate (81°C), poly n-butyl methacrylate (
20℃), polyisobutyl, methacrylate (67℃)
, polyphenylacrylate (55°C), polyρ-cyanophenyl acrylate (90°C), polymethyl acrylate (8°C), polyethyl acrylate (23°C),
Polypropyl acrylate (44°C), polybutyl acrylate (56°C).

These acrylic resins may be used singly, in combination of two or more, or as a copolymer of their monomers.

The amount of acrylic resin used in the hack layer is 1 to 30% by weight, preferably 3 to 10% by weight. If the content of the acrylic resin exceeds 30% by weight, the slipping properties necessary for the hack layer will be lost, and if the content is less than 1% by weight, the binding property with the polyester film of the back layer will decrease. If the adhesiveness between the back layer and the polyester film is low, during the manufacturing process, the hack layer, especially the raised parts at both ends, will be removed by the guide roll where the back surface is in contact, and the hack layer will gradually be removed from the guide roll. Silicone rubber becomes thicker and has rubber elasticity. It also has rubber elasticity,
If it becomes sticky, problems such as meandering during coating may occur.
Eventually, the silicone rubber on the guide roll transfers to the film in the form of particles, staining the product.

The coating thickness of this mixture of silicone rubber and acrylic resin is 0.001 to 0.1 μm, preferably 0.008 to 0.1 μm.
It is used at a thickness of 0°08 μm; if it is thin, it will have poor sliding properties, and if it is too thick, the deformation resistance of the silicone rubber will be large, resulting in stickiness and poor sliding. It is desirable that the shearing property has a dynamic friction coefficient of 0.1 or less. If curing is required, drying is carried out at 120°C for about 30 seconds, and if complete curing is not required, drying at 40°C to 100°C for about 3 to 15 seconds is sufficient to volatilize the solvent. It is.

The support used in the present invention has a thickness of 2-2
Plastic films of about 5 μs, such as polyester films, polycarbonate films, triacetyl cellulose films, and nylon films, are suitable.

Further, the heat-sensitive transfer layer in the present invention may have a conventionally known ink layer structure, and contains a lubricant, a resin, and a colorant as main components. In the case of 2, examples of the lubricant include carnauba wax, candelilla wax, paraffin wax, polyethylene wax, stearamide, stearic acid, and yatyli alcohol.

Examples of resins include styrene resins, epoxy resins, ethylene-vinyl acetate copolymer resins, polyester resins,
Examples include acrylic resin, polyamide resin, polyacetal resin, vinyl chloride resin, polyolefin resin, guanamine resin, phenol resin, urethane resin, and tetrafluoroethylene resin. In addition, as the colorant, inorganic and organic dyes and pigments used in printing inks, dyes, etc. can be used, such as carbon blank, Lake Red C, benzidine yellow, phthalocyanine green, phthalocyanine blue, dioxide Examples include pigments such as titanium, iron black, and hengara, and dyes such as direct dyes, oil dyes, basic dyes, and acid dyes.

In the present invention, the back layer is made of a silicone rubber/acrylic resin mixture whose heat resistance is inferior to that of silicone resin.
The reason why a more excellent stain prevention effect can be obtained is considered to be due to the following reason.

In other words, the stick prevention effect prevents the underlying support film from melting due to the heat-resistant protection of the silicone resin, and also prevents the silicone resin from melting even if the support film melts, separating it from the thermal head. Unlike that, the present invention provides a thin film that does not have very good heat resistance, but it is highly slippery and is transported before the support film melts and adheres to the thermal head, so it seems to have a high stick prevention effect. .

In the present invention, in addition to providing the above-mentioned release layer, a brimer layer may be provided between the support and the back layer to improve the adhesion between the two, and a brimer layer may also be provided on the heat-sensitive transfer layer. An overlayer can be provided to improve heat sensitivity, fixability, etc.

[Effect of the invention] The heat-sensitive transfer sheet of the present invention has a coating thickness of 0.001 to 0.1
Since the back layer made of 1zrn silicone rubber/acrylic resin mixture is provided on the back side of the support, it has good sliding properties and transportability, and the hack layer is thin and does not require long-term curing at high heat. Since there is no heat shrinkage of the support film, as a result, images of good quality can be obtained with this transfer sheet.

In addition, the heat-sensitive transfer sheet of the present invention has good productivity and is advantageous in terms of cost. Moreover, since the adhesiveness between the support film and the back layer is good, the heat-sensitive transfer sheet of the invention The guide roll is less likely to get dirty.

〔Example〕

Next, the present invention will be explained in more detail with reference to Examples. Note that all parts shown below are based on weight.

Example 1 Coating liquid for ink layer A mixture of the following composition was dispersed in a ball mill for 12 hours,
A coating liquid for an ink layer was prepared.

Carnauba wax 70 parts Carbon blank 20 parts Toluene
900 parts Coating liquid for release layer A mixture having the following composition was dispersed in a ball mill for 8 hours to prepare a coating liquid for release layer.

Carnauba wax 85 parts (manufactured by Cal Co., Ltd.) Toluene 900 parts Coating liquid for back layer A mixture having the following composition was dissolved and dispersed to prepare a coating liquid for back layer.

Solid content 40%; Tg 105°C) 1,000 parts of toluene on a 4.5 μm thick polyester (PET) film.
Apply the above coating liquid for the back layer with a smoother, and apply 1 coat at 80℃.
It was dried for 0 seconds to form a hack layer with a thickness of 0.02 μm.

Next, on the opposite side of this back layer-formed PET film,
The above coating liquid for release layer was applied and dried at 40° C. for 10 seconds to form a release layer with a thickness of 1.5 μm.

Subsequently, applying the coating liquid for the ink layer on the release layer,
The ink layer was dried at 70° C. for 10 seconds to form an ink layer with a thickness of 2 μm, thereby producing a heat-sensitive transfer sheet of the present invention.

Example 2 Coating liquid for ink layer A mixture of the following composition was dispersed in a ball mill for 12 hours,
A coating liquid for an ink layer was prepared.

Carnauba wax 65 parts Carbon blank 20 parts Toluene
900 parts Back layer coating liquid A mixture having the following composition was dissolved and dispersed to prepare a back layer coating liquid.

7g 50°C) 7g 105°C) The above coating liquid for the back layer was applied with a smoother onto a 4.5μ0 thick PET film, dried at 80°C for 10 seconds,
A back layer having a thickness of 0.02 μm was formed.

Next, on the opposite side of this back layer-forming 1PET film,
The above coating liquid for ink layer was applied and dried at 70° C. for 10 seconds to form an ink layer with a thickness of 4 μm to prepare a heat-sensitive transfer sheet of the present invention.

Example 3 Coating liquid for back layer A mixture having the following composition was dissolved and dispersed to prepare a coating liquid for back layer.

1,000 parts of toluene (solid content: 30%; 7 g, 65°C) The above coating liquid was applied with a smoother onto a 4.5 μm thick PET film, and dried at 80°C for 10 seconds.
A back layer having a thickness of 0.02 part m was formed.

Thereafter, in the same manner as in Example 1, a release layer and an ink layer were formed on the opposite side of the PET film to create a heat-sensitive transfer sheet of the present invention.

Comparative Example 1 A heat-sensitive transfer sheet for comparison was prepared in the same manner as in Example 1, except that the acrylic resin solution was removed from the back layer coating liquid of Example 1.

Comparative Example 2 Coating liquid for back layer A mixture having the following composition was dissolved and dispersed to prepare a coating liquid for back layer.

Silicone resin 10 parts (KR
266; manufactured by Shin-Etsu Chemical Co., Ltd.) Curing agent (D-11; manufactured by Shin-Etsu Chemical Co., Ltd.) 1 part toluene 49 parts Thickness 4
．． The above coating liquid for the back layer was applied onto a 5 μm PET film and dried and cured at 150°C for 20 minutes to give a film thickness of 3 μm.
A back layer was formed. It was observed that the film shrank and wrinkled after drying.

Thereafter, in the same manner as in Example 1, a release layer and an ink layer were formed on the opposite side of the PET film to create a comparative thermal transfer sheet.

Comparative Example 3 Coating liquid for back layer A mixture having the following composition was dissolved and dispersed to prepare a coating liquid for back layer.

Silicone resin ] 0 parts (K
R255; manufactured by Shin-Etsu Chemical Co., Ltd.) Toluene 50 parts Thickness 4
．． The above coating liquid for the back layer was applied onto a 5 μm PUT film and dried and cured at 100°C for 10 minutes to give a film thickness of 0.5 μm.
A back layer of μ■ was formed.

Thereafter, in the same manner as in Example 1, a release layer and an ink layer were formed on the opposite side of the PET film to create a comparative thermal transfer sheet.

Comparative Example 4 The back layer coating liquid of Comparative Example 2 was coated on a 4.5 μm thick PET film in the same manner as Comparative Example 2 and dried at 100°C for 10 seconds, but the drying was insufficient and the coating failed. During construction, the guide rolls immediately became dirty.

Comparative Example 5 The coating liquid for the back layer of Comparative Example 2, in which 49 parts of toluene was replaced with 1,000 parts, was applied to a PET film with a thickness of 4.5 μm.
It was applied onto a film and dried at 100° C. for 10 seconds to form a back layer with a thickness of 0.02 μm.

Thereafter, in the same manner as in Example 1, a release layer and an ink layer were formed on the opposite side of the PET film to create a comparative thermal transfer sheet.

Tests regarding sliding properties (coefficient of dynamic friction), sticking (conveying properties), and coating properties were conducted on the heat-sensitive transfer sheets obtained above. The results are shown in Table 1. The test conditions are as follows.

(+) Coefficient of Dynamic Friction Using a surface property measuring tester manufactured by HEIDON, a steel ball was brought into contact with the hack surface and was slid at a speed of 75 mm/min under a load of 50 g.

(2) Sticking (transportability) A test was conducted using a thermal transfer simulator manufactured by Okura Electric Co., Ltd. under the following conditions.

Thermal head (KIT manufactured by Kyocera) Head pressure: 300 g/cm Ribbon tensile tension: 14001 scm Printing speed, 2 inches/sec Printing energy: 30 nni/m 112 applied Hals
All line continuous 320 pulse evaluation criteria ○ - Ribbon breakage and sticking did not occur during conveyance.

×: The ribbon was not transported and the ribbon broke due to the stick.

Δ: Transport takes a little longer, but stains occur and the ribbon breaks.

(3) Heat Resistance Tests were conducted using a thermal transfer simulator manufactured by Okura Electric Co., Ltd. under the following conditions.

Thermal head Kyocera KMT Head pressure: 300g/crn Applied energy 30m i 7mm2 applied Hals All lines continuous 64 pulses Evaluation criteria ○ - Ribbon does not break.

×...The ribbon broke.

(4) Coating property A wire coater was used, and the coater heads were set at the following three locations.

No., l Coater head/back layer No. 2 Coater head/Peeling layer No. 3 Coater head/ink layer The dryer length is 10 m each, and the coating speed is 60 rn/min.
It was a minute.

The number of coated meters at which the back side of the roll from the No. 1 dryer outlet to the No. 2 kneader head became dirty and started meandering was measured.

Note) ×: The ink layer was not applied because the roll got dirty quickly and I stopped.

(X) Comparative Examples 2 and 3 were described as such because mechanical coating was impossible under the above drying conditions.

From the results in Table 1, it can be seen that the heat-sensitive transfer sheet of the present invention does not have very good heat resistance compared to the comparative heat-sensitive transfer sheet, but
Due to its good sliding properties, it has good transportability, and also has good binding properties between the support film and the back layer, so it is difficult to get dirty on the guide roll that comes into contact with the back surface during manufacturing and coating. .

[Brief explanation of the drawing]

FIGS. 1 and 2 are schematic cross-sectional views of a heat-sensitive transfer sheet according to the present invention. 1 Support, 2 Heat-sensitive transfer layer (ink layer), 3 Back layer, 4 Thermal head, 5 Release layer. Patent applicant Rico Co., Ltd. - Representative patent attorney Toshiaki Ikeura (1 person) Figure 1 Figure 2

Claims (2)

[Claims] (1) A heat-sensitive transfer sheet in which a heat-sensitive transfer layer is provided on the surface of a support and a back layer is provided on the back surface of the support, in which the back layer is made of a mixture of silicone rubber and acrylic resin, and the coating film is Thickness is 0.001~0.1
A heat-sensitive transfer sheet characterized by having a thickness of μm. (2) The coating thickness of the back layer is 0.008 to 0.08μ
The heat-sensitive transfer sheet according to claim (1), which is m.