JP3052248B2 - Image receiving paper for thermal transfer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention is used in combination with a transfer sheet having a transfer layer containing a heat transferable dye such as sublimation or vaporization,
The present invention relates to a thermal transfer image receiving paper having a dyeing layer on which dye sublimated or vaporized by heating the transfer sheet is dyed.

[Conventional technology]

2. Description of the Related Art A method of reproducing an image in the form of a hard copy such as a photograph from an electric image signal obtained from a video camera, a still video camera, a television, a video disk, a photographic transmission device, and the like has been actively studied. As one of the influential methods, a thermal transfer image recording method is currently attracting attention.

Thermal transfer image recording refers to a transfer sheet having a transfer layer containing a heat transferable dye while passing an electric signal containing image information to a thermal head in which electric heating elements of 4 to 16 dots per mm are arranged in a line. A method is known in which a transfer sheet is heated with a thermal head in a state where the sheet is superimposed, and a dye contained in a transfer layer is transferred and dyed on an image receiving sheet to form a dye image on the image receiving sheet. .

This method has an advantage that an intermediate color tone can be easily obtained because the transfer amount of the dye is determined according to the thermal energy amount of the thermal head.

[Problems to be solved by the invention]

A thermoplastic resin layer, such as a sheet, a microvoid layer or a film, is laminated on a paper substrate, and is used to form this laminate in a thermal transfer image receiving paper obtained by applying a dyeing agent to the laminate. The usual adhesives have insufficient cushioning properties of the receiving paper. For this reason, the adhesion between the transfer sheet and the image receiving paper deteriorates. Also, if there is delicate dust or foreign matter between the transfer sheet and the image receiving paper during recording, or unevenness on the surface of the thermal head, the adhesion will be poor. As a result, there are disadvantages of poor image quality, such as non-uniform density of the recorded image (irregularity), dot-like white spots, and reduced image density as a whole.

Further, in these receiving papers, heat generated by the thermal head cannot be efficiently transmitted to the receiving paper due to poor adhesion.
The sublimation amount of the dye does not follow the given electric energy change, the color density is not stable, and the sensitivity is poor.

Heating with thermal head is about 30
It is important to prevent heat loss when heating time is several milliseconds to several tens of milliseconds at 0 ° C, especially when low energy is applied for several milliseconds, and the heat insulation effect is substantially required only on the surface. , About 20 μm from the surface.

As described above, at present, all of the image quality (white spots, color unevenness), sensitivity, and the like are not satisfied.

An object of the present invention is to provide a high-quality, high-sensitivity image receiving paper.

[Means for solving the problem]

In general, the present invention relates to a thermal transfer image-receiving paper, in which the same or different synthetic resins are laminated in a single-layer or multi-layer structure on both front and back surfaces of a paper base material via an adhesive, In a thermal transfer image receiving paper having a surface layer coated with a dye, the adhesive is a urethane resin having a glass transition point of 15 ° C. or lower.

 The features of the present invention are as described below.

A laminated film formed on a paper base material using a urethane resin having a glass transition point of 15 ° C. or less, preferably in the range of -10 to 10 ° C., has extremely suitable cushioning properties as an image receiving paper for thermal transfer. is there.

Therefore, when the transfer sheet is superposed on the image receiving paper and heated by the thermal head, the laminated film of the image receiving paper serves as a cushion, and the adhesion between the thermal head, the transfer sheet and the image receiving paper is remarkably improved. Therefore, high image quality without color unevenness and white spots in the image can be obtained.

Due to the improved adhesion, the heat generated by the thermal head can be efficiently transmitted to the image receiving paper, so that the amount of sublimation of the dye closely follows the applied electric energy change, and the sensitivity is improved.

 A method for forming a laminate will be described.

The laminate formed on the paper substrate may be composed of only one layer or two or more layers. In addition, the formation method is 1
Seeds may be used, or two or more different methods may be used.

When forming the laminate, the urethane resin is used as an adhesive, and between paper and a synthetic resin, preferably a thermoplastic resin.
Alternatively, a layer is adhered between the synthetic resin layers, for example, between thermoplastic resins.

Known methods such as an extrusion lamination method and a dry lamination method are employed as a method for forming these laminates.

In the case of the extrusion lamination method, the urethane resin may be subjected to anchor coating treatment as an interlayer adhesive on a paper base material and then extrusion-laminated, or the base material may be used to enhance the adhesive strength between the paper base material and the synthetic resin. May be subjected to a known surface activation treatment such as a corona treatment or a frame treatment, followed by extrusion lamination as described above.

The extrusion lamination can be performed using a known method and apparatus.For example, a thermoplastic resin is extruded from a die of an extruder at a resin temperature of 280 to 340 ° C. to form a molten thin film, and the molten thin film is guided to a pressure roll. On the other hand, the urethane resin is applied to the paper base material, which has been untreated or subjected to the surface activation treatment described above, and has been guided to a pressure roll similarly.
It is performed by pressure bonding laminating after anchor coating treatment. In the case of the dry lamineo method, the urethane resin is applied as an interlayer adhesive on the adhesive surface of a non-stretched or stretched film of a thermoplastic resin, for example, a uniaxially stretched film or a biaxially stretched film in a transverse direction, and dried in a drying oven. The stretched film obtained by drying the anchor-coated film is guided to a thermocompression roll, and the adhesive surface is dry-laminated on a paper substrate similarly guided to the thermocompression roll.

The shape of the laminate may be a thermoplastic resin layer obtained by an extrusion lamination method, or a layer made of a known or commercially available thermoplastic resin, for example, a sheet, a microvoid layer or a film.

The following can be used as the thermoplastic resin. Only one type may be used, or two or more types may be mixed and used by a known method.

a) Olefin-based resin Examples of the polyolefin-based resin include those mainly containing monoolefin polymers and copolymers such as ethylene, propylene and butene. For example, high density polyethylene, medium density polyethylene, linear low density polyethylene, low density polyethylene, crystalline polypropylene, crystalline ethylene-propylene-block copolymer, polybutene, poly-3-methylbutene-1, poly-4-methyl Penten-1, ethylene-vinyl acetate copolymer and the like.

b) Vinyl chloride resin Examples of the vinyl chloride resin include polyvinyl chloride, polyvinylidene chloride, a vinyl chloride-vinyl acetate copolymer, and a mixture thereof.

c) Ester-based resin Examples of the ester-based resin include polyethylene terephthalate and polybutylene terephthalate.

d) Amide resin Nylon 6, nylon 6-6, nylon 6-10, nylon 11, nylon 12, and the like.

e) Styrene resin Polystyrene, acrylonitrile-styrene copolymer, acrylonitrile-butadiene-styrene terpolymer and the like are exemplified.

As the urethane resin used in the present invention, a resin obtained by a reaction between a polyol and a polyisocyanate is suitably used. Examples of polyols include ethylene glycol, 1,2-propanediol, 1,3-butanediol,
At least one of aliphatic diols such as 4-butanediol, 1,5-pentanediol, 1,6-hexanediol, neopentyl glycol, diethylene glycol, dipropylene glycol, polyethylene glycol and polypropylene glycol, and succinic acid and adipic acid Polyester diol or ethylene oxide, propylene oxide, tetrahydrofuran, γ-butyrolactone, ε-caprolactone or the like obtained by reacting a single or mixture of dicarboxylic acids such as azelaic acid, sebacic acid, isophthalic acid and terephthalic acid. Oxyalkylene diol or polyester alkylene diol is exemplified.

Examples of the polyisocyanate include tolylene diisocyanate, diphenyl methane diisocyanate, hexamethylene diisocyanate, xylylene disyl methane diisocyanate, isophorone diisocyanate, tolylene diisocyanate trimer, and hexamethylene diisocyanate trimer. Further, in some cases, ethylene glycol, 1,2-
Propanediol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, neopentyl glycol, diethylene glycol, dipropylene glycol, ethylenediamine, hexamethylenediamine, piperazine, hydrazine , Isophoronediamine, dicyclohexylmethanediamine, N-
There is a polymer obtained by reacting at least one of compounds such as methyldiethanolamine, monoethanolamine, glycerin, trimethylolpropane, and pentaerythritol. Of course, such urethane resins can be used alone or in combination.

However, among urethane resins obtained by various combinations and weight ratios of the above polyols and polyisocyanates, those having a glass transition point of 15 ° C. or lower are preferred for use in the present invention.

When a urethane resin having a glass transition point exceeding 15 ° C. is used, the cushioning property required for the present invention cannot be obtained, and therefore, high image quality and high sensitivity cannot be obtained as a thermal transfer image-receiving paper.

The organic solvent used for the urethane resin may be any solvent as long as it can dissolve these polymers. For example, aromatic hydrocarbons such as toluene and xylene; methanol, iso-propyl alcohol, n-butanol, iso- −
Alcohols such as butanol; esters such as ethyl acetate and butyl acetate; methyl ethyl ketone and methyl-iso-
Ketones such as butyl ketone; cyclic ethers such as tetrahydrofuran and dioxane; methyl cellosolve, ethyl cellosolve, ethyl cellosolve acetate, N-methylpyrrolidone, dimethylformamide and the like are used alone or in combination of two or more.

The application of the polyurethane-based solution comprising the urethane resin and the organic solvent to a substrate or a film is performed by a known method such as a roll method, a spray method, or a doctor method.

The paper used as the support (substrate) may be rigid plain paper. However, in terms of surface smoothness, whiteness, and hidden payability, smoothness such as high quality paper, coated paper, art paper, and cast coated paper (JIS P- 811
9) is 100 seconds or more, preferably 200 seconds or more.

 Further, an undercoat layer may be provided by a conventional method.

Further, in order to obtain a good curl balance on the opposite side of the laminate formed above the paper base material, a back surface layer may be formed. The back layer may be a conventional one, and may be the above-mentioned thermoplastic resin or a sheet made of the same, a microvoid layer, a film, or the like. These back layers can be formed by, for example, the following known method.

For bonding the microvoid layer or film made of thermoplastic resin, a solvent-type lamination method such as dry lamination or extrusion lamination is used, and for coating of thermoplastic resin, a blade coater, an air knife coater, and a roll coater are used. An ordinary coating machine such as a bar coater or a gravure coater, or a coating and coating mold forming method using a spray coating machine is used.

An image receiving paper is obtained by applying a dye for a heat transferable dye to a composite substrate comprising the laminate, paper (and undercoat) and a surface layer produced in this manner.

 The dye for the heat transfer dye is applied by a known method below.

Image receiving layer, that is, a dye dye coating layer (dye layer)
Is a resin showing dyeability to a sublimable or vaporizable dye,
Rubber, wax or a mixture thereof with an organic and / or inorganic filler is used. Alternatively, a release agent may be included to facilitate release.

The resin, rubber, wax, or the like may be used by dispersing it in water or by dissolving it in an organic solvent.

Examples of resins, rubber, waxes include, for example, aminoalkyd resins, polyamides, polyurethanes, polyvinyl chloride, polyvinyl acetate, polyesters, acrylic resins, acetal resins, polyvinyl alcohol, polyvinylidene chloride, polyvinyl acetal, polystyrene,
Adhesives consisting of rubber, such as polycarbonate, epoxy resin, styrene-butadiene rubber (SBR) and nitrile rubber (NBR), water-insoluble polymers such as ethyl cellulose and petroleum resin, or carnauba waxes, wood wax, etc. It is used in combination with solid waxes such as vegetable waxes, animal waxes such as beeswax, seraxa wax, petroleum waxes such as microcrystalline wax and paraffin wax, and synthetic waxes such as oxidized waxes and ester waxes.

As the inorganic filler, synthetic silica such as white carbon having an average particle size of 0.5 μm or less, inorganic pigments such as clay, talc, aluminum sulfate, titanium dioxide, and zinc oxide can be used. Preferably, white particles having an average particle size of 0.1 μm or less are used. Inorganic pigments such as synthetic silica such as carbon and light or heavy calcium carbonate can be used.

As the organic halar, various polymer fine particles are employed, and the particle diameter is preferably 10 μm or less.
Examples of the polymer constituting the organic filler include methyl cellulose, ethyl cellulose, polystyrene, polyurethane, carbon / formalin resin, melamine resin, phenol resin, iso (or diiso) butylene / maleic anhydride copolymer, and styrene / maleic anhydride. Acid copolymer,
Examples include polyvinyl acetate, polyvinyl chloride, vinyl chloride / vinyl acetate copolymer, polyester, polyacrylate, polymethacrylate, and styrene / butadiene / acrylic copolymer.

For the coating, an ordinary coating machine such as a blade coater, an air knife coater, a roll coater, a bar coater or the like, or a size press, a gate roll device or the like is used.

The thickness of the dyeing layer is usually 0.5 to 20 μm, preferably 3 to 15 μm.
μm.

〔Example〕

Hereinafter, the present invention will be described more specifically with reference to Examples, but the present invention is not limited thereto.

Example-1 Polyol (Takeda Pharmaceutical, Takerakku A367H; solid content 35
%, Viscosity 4,000 to 7,000 cps <25 ° C>) 25 parts by weight, polyisocyanate (Takeda Pharmaceutical, Takenate A-7; solid content 80)
%, Viscosity of 1,000 to 4,000 cps <25 ° C., 5% NCO component) and 70 parts by weight of ethyl acetate were mixed to prepare an adhesive solution having a glass transition point of 0 ° C. as a urethane resin.

Apply 5 g of this solution with a 75 mesh gravure coater.
/ m ² (solid content) was applied to a microvoid layer of commercially available biaxially oriented polypropylene (Toyobo Toyopearl SS 35 μm).
Then, the stretched microvoid layer subjected to anchor coating obtained by drying in a drying oven at 80 ° C. is led to a heating and pressing roll at 80 ° C., and a cast with a smoothness of 150 seconds is also guided to the heating and pressing roll from the other side. The adhesive surface was adhered to the coated paper, and the same microvoid layer was adhered to the back surface in the same manner as described above to obtain a base material for an image receiving paper.

In order to provide a dyeing layer on this substrate, the following dyeing agent coating solution was applied with a bar coater of about 20 g / m ² and dried.

As a result, a sublimation type thermal transfer image receiving paper having a dyeing layer of about 7 μm was obtained.

○ Dyeing agent coating liquid composition Polyester resin 10 parts by weight [Product name: TP-220, Nippon Gohsei Co., Ltd.] Amino-modified silicone 0.5 parts by weight [Product name: KF-393, Shin-Etsu Chemical Co., Ltd. product] Methyl ethyl ketone 15 parts by weight Xylene 15 parts by weight A transfer sheet in which a sublimable dye is coated on a polyester film is superimposed on the obtained image receiving paper, and a thin film line type thermal head of 8 dots / mm [type RH- manufactured by Ricoh Co., Ltd.]
A48-01], color printing was performed at a line density of 8 lines / mm under the following conditions, and both the image quality and the transfer density were very good.

Therefore, the image quality and sensitivity of the image receiving paper were sufficiently satisfied.

Color printing conditions Recording Power: 0.25 W / dot head heating time: 1 to 10 milliseconds Example-2 The mixing ratio of the interlayer adhesive solution used was 20 parts by weight of polyol, 10 parts by weight of polyisocyanate, and 70 parts of ethyl acetate. An image receiving paper was prepared and evaluated in the same manner as in Example 1, except that the glass transition point as a urethane resin was changed to 5 ° C. as parts by weight.

Comparative Example-1 A urethane resin to be used was prepared from a polyol (Takeda Pharmaceutical Co., Ltd., Takerak A310; solid content 50%, viscosity 1,000 to 4,000 cps <25 ° C.).
>), Polyisocyanate (Takeda Pharmaceutical, Takenate A-
3; solid content 75%, viscosity 600-3,000 cps <25 ° C>, NCO component 13
%), Except that the glass transition point of the urethane resin was changed to 30 ° C., and an image receiving paper was prepared and evaluated in the same manner as in Example-1.

Comparative Example-2 The mixing ratio of the interlayer adhesive solution used in Comparative Example-1 was 28 parts by weight of polyol, 2 parts by weight of polyisocyanate, and 70 parts by weight of ethyl acetate, except that the glass transition point as a urethane resin was changed to 25 ° C. Prepared an image receiving paper in the same manner as in Example 1, and evaluated.

Color Print Evaluation Image Quality The heating time of the head was recorded in 10 steps every 1 millisecond from 1 millisecond to 10 milliseconds, and the recording uniformity of the recorded material at each step was visually determined.

：: Good uniformity of the recorded matter at each stage. 少 し: Slight recording unevenness in a low-density recorded matter (recorded matter in the case where the head heating time is short) X: Large recording unevenness in a low-density recorded matter.

Sensitivity Density meter TR manufactured by Macbeth of the United States when the head heating time is recorded in 1 to 10 milliseconds.
It was measured at -927 and evaluated comprehensively.

：: good sensitivity at each stage △: 〃 fairly good ×: 不良 poor [Effect of the Invention] In the image-receiving paper of the present invention, the urethane resin used as an adhesive has a glass transition point of 15 ° C. or less, and has a cushioning property. This is a practically excellent image-receiving paper with good properties and excellent image quality and sensitivity.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Izumi Hosoda 3-10, Ushidori, Kurashiki-shi, Okayama Prefecture Inside the Mizushima Plant of Mitsubishi Kasei Co., Ltd. (56) References JP-A-62-23391 (JP, A) JP-A-63-91286 (JP, A) JP-A-61-144394 (JP, A) JP-A-2- 106391 (JP, A)

Claims (1)

(57) [Claims] 1. A thermal transfer image receiving apparatus in which the same or different kinds of synthetic resins are laminated on the front and back surfaces of a paper base material in a single-layer or multilayer structure via an adhesive, and a dyeing agent is applied to the surface layer. An image receiving paper for thermal transfer, wherein the adhesive is a urethane resin having a glass transition point of 15 ° C. or lower.