JPH06143841A - Sublimation type thermal transfer material - Google Patents

Abstract

PURPOSE:To obtain a transfer image excellent in gradation properties by preventing the lowering of the adhesion of a sublimation type ink layer with a polyester film under high temp. and high humidity conditions by providing an easy bonding layer containing an acrylic resin having a crosslinkable functional group and polyethyleneimine as main constituents between the polyester film and the sublimation type ink layer. CONSTITUTION:A sublimation type thermal transfer material is obtained by providing a sublimation type ink layer on the single surface of a polyester film through an easy bonding layer and providing a sticking preventing layer on the other surface thereof. The easy bonding layer is formed from a compsn. obtained by mixing 3-20 pts.wt. of polyethyleneimine with 100 pts.wt. of an acrylic resin having one or more kind of a crosslinkable functional group, for example, a carboxyl group, a methylolated amide group or a methylolated amino group in its molecule. By this constitution, a sublimation type thermal transfer material good in the adhesion with the ink layer, showing high adhesion even under high temp. and high humidity conditions and good in hue reproducibility is obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sublimation type heat-sensitive transfer material, and more specifically, it forms a transfer image having excellent adhesiveness of an ink layer, no over-transfer even in a high temperature and high humidity environment, and excellent gradation. The present invention relates to a sublimation-type heat-sensitive transfer material that can be used.

[0002]

2. Description of the Related Art Biaxially oriented polyester films are excellent in mechanical properties, electrical properties, dimensional stability, transparency, heat resistance and the like, so that they are used in magnetic recording materials, packaging materials, electrical insulating materials, various kinds of materials. It is widely used as a base film for many applications such as photographic materials and graphic arts materials. In particular, in recent years, it has shown remarkable growth as a thermal transfer material for OA and FA. The heat-sensitive transfer material is roughly classified into an ink layer in which various pigments are mixed in a binder such as wax, which is melted by heat and transferred to the transfer paper, and a dye having a heat sublimation property is mixed in the binder, In some cases, only the dye sublimes due to heat and is absorbed by the receiving layer of the transfer paper to form a gradation image. Among the above, the sublimation type thermal transfer material sublimates only the dye, therefore, high adhesion is required between the binder and the base film, and it is important that the adhesion is not particularly deteriorated due to environmental change or aging, If the adhesiveness is insufficient, a phenomenon called so-called over-transfer occurs, in which the dye-containing resin layer migrates to the transfer paper and remarkably deteriorates the gradation. Generally, since the surface of the biaxially oriented polyester film is highly crystallographically oriented, the adhesiveness is poor, and even if the sublimation type ink layer is directly applied, it does not adhere at all. For this reason, in order to make the adhesiveness with the ink layer strong, physical treatment such as corona discharge treatment, plasma treatment, ultraviolet irradiation treatment in various gas atmospheres on the film surface, alkali, trichloroacetic acid, amine, phenol Chemical treatment with a kind or the like, or a treatment method using these in combination has been attempted, but none of them has sufficient adhesion. In addition, the surface of a polyester film is widely used because of its advantages such as easy adhesion by treatment with a primer, safety in processing process and maintenance of high quality of processed film products. A method of performing a primer treatment (for example, applying a water-based coating material such as polyester, acryl, and urethane and then stretching to form a coating layer) is considered to be promising in terms of process simplification and manufacturing cost, and is actively carried out. For example, there is known one in which a stretched coating layer is provided after coating a reaction product of acrylic and polyester (JP-A-1-171988).

[0003]

However, the above-mentioned conventional technique has the following problems. That is, when a water-soluble polyester or a water-dispersible polyester and a resin containing these are laminated, the moisture resistance and water resistance of the coating film are inferior even if the desired easy adhesion is obtained, so the adhesion under high humidity And the easy-adhesion layer is liable to be dyed by the dye in the binder, resulting in insufficient original color density and gradation when transferred to a receiving paper.
The present invention solves these drawbacks, has excellent adhesion to a sublimation-type ink layer, does not deteriorate adhesion under high temperature and high humidity, and obtains a transferred image with excellent gradation. Is provided.

[0004]

According to the present invention, a sublimation type ink layer is provided on one surface of a polyester film via an easy-adhesion layer, and a stick prevention layer is provided on the opposite surface of the surface provided with the easy-adhesion layer. The sublimation type thermal transfer material is characterized in that the easy-adhesion layer is mainly composed of an acrylic resin having at least one crosslinkable functional group in the molecule and polyethyleneimine as main constituents. It is what

The polyester of the polyester film in the present invention is a general term for polymers having an ester bond as the main chain of the main chain, and particularly preferred polyesters are polyethylene terephthalate and polyethylene 2,6.
-Naphthalate, polybutylene terephthalate, polyethylene α, β-bis (2-chlorophenoxy) ethane 4,4, -dicarboxylate, and the like. Among them, polyethylene terephthalate is the most preferable in view of quality and economy. preferable. Therefore, hereinafter, the description will proceed with polyethylene terephthalate (hereinafter referred to as PET) as a typical example of polyester.

PET is 80 mol% or more, preferably 9
Although 0 mol% or more, more preferably 95 mol% or more, has ethylene terephthalate as a repeating unit,
Other dicarboxylic acid components and diol components may be used within this limited amount range. Known additives such as heat resistance stabilizer, oxidation resistance stabilizer, weather resistance stabilizer, ultraviolet absorber, organic lubricant, pigment, dye, organic or inorganic fine particles, filler, antistatic agent, etc. You may mix | blend a nucleating agent etc. The PET film has an intrinsic viscosity of 0.40 to 1.20 d (measured in orthochlorophenol at 25 ° C.).
l / g, preferably in the range of 0.50 to 0.80 dl / g is suitable for the present invention.

The PET film using the above PET is preferably biaxially oriented when the easily adhesive layer is laminated, and the biaxially oriented PET film is a PET sheet or film in a non-stretched state. It is made by stretching about 2.5 to 5 times in each of the longitudinal direction and the width direction, and shows a biaxially oriented pattern in wide-angle X-ray diffraction.

The thickness of the PET film is not particularly limited, but is usually 1 to 1 from the viewpoint of mechanical strength and heat transferability.
30 μm, preferably 2 to 15 μm, more preferably 3
10 to 10 μm.

In addition, the PET film is easy to transport,
It is preferable that the surface is roughened to some extent.
Measurement according to B-0601-1976 (cutoff:
0.25 mm) center line average roughness is 0.05 to 0.4
Those having a surface state of μm are preferable.

The acrylic resin which is the main constituent of the easy-adhesion layer of the present invention has at least one crosslinkable functional group in the molecule. As such a crosslinkable functional group, a carboxyl group, a sulfonic acid group, a hydroxyl group, an amide group,
Examples thereof include an amino group and an epoxy group, but are not particularly limited thereto. Such an acrylic resin can be produced by a known method, and the following monomer components can be exemplified as the monomer component constituting the acrylic resin, but the monomer components are not particularly limited as long as they satisfy the above requirements. Alkyl acrylate, alkyl methacrylate (as the alkyl group, methyl group, ethyl group, n-propyl group,
(Isopropyl group, n-butyl group, isobutyl group, t-butyl group, 2-ethylhexyl group, lauryl group, stearyl group, cyclohexyl group, phenyl group, benzyl group, etc.) as a basic skeleton, and the above crosslinkable functional group is further added. In order to do so, it is copolymerized with the following monomers. That is, as the crosslinkable functional group, a carboxyl group, an acid anhydride group, a sulfonic acid group, an amide group or an alkylolated amide group, an amino group (including a substituted amino group) or an alkylolated amino group, a hydroxyl group, Examples thereof include epoxy groups, and salts and esterified products thereof may be copolymerized.

Examples of the compound having a carboxyl group or a salt thereof or an acid anhydride group include acrylic acid, methacrylic acid, itaconic acid, maleic acid, fumaric acid, crotonic acid, alkali metal salts and ammonium salts of these carboxylic acids, Alternatively, an anhydride or the like may be used.

Examples of the compound having a sulfonic acid group or a salt thereof include vinyl sulfonic acid, styrene sulfonic acid, alkali metal salts and ammonium salts thereof.

Examples of the compound having an amide group or an alkylolated amide group include acrylamide, methacrylamide, N-methylmethacrylamide, methylolacrylamide, methylolmethacrylamide, ureido vinyl ether, β-ureidoisobutyl vinyl ether and ureidoethyl acrylate. And so on.

Examples of the compound having an amino group or an alkylolated amino group or a salt thereof include diethylaminoethyl vinyl ether, 2-aminoethyl vinyl ether, 3-aminopropyl vinyl ether, 2-aminobutyl vinyl ether, dimethylaminoethyl methacrylate and dimethylamino. Examples thereof include ethyl vinyl ether, those obtained by methylating their amino groups, those obtained by quaternary chlorination with alkyl halides, dimethylsulfate, sultone and the like.

The compounds having a hydroxyl group include β-hydroxyethyl acrylate, β-hydroxyethyl methacrylate, β-hydroxypropyl acrylate, β
-Hydroxypropyl methacrylate, β-hydroxy vinyl ether, 5-hydroxypentyl vinyl ether, 6-hydroxyhexyl vinyl ether, polyethylene glycol monoacrylate, polyethylene glycol monomethacrylate, polypropylene glycol monoacrylate, polypropylene glycol monomethacrylate and the like can be mentioned.

Examples of the compound having an epoxy group include glycidyl acrylate and glycidyl methacrylate.

Of the above-mentioned crosslinkable functional groups, a carboxyl group,
A methylolated amide group and a methylolated amino group are particularly preferable in terms of adhesion to a sublimation type ink.

In addition to the above, the following compounds may be used in combination. That is, acrylonitrile, methacrylonitrile, styrenes, butyl vinyl ether, maleic acid mono- or dialkyl esters, itaconic acid mono- or dialkyl esters, methyl vinyl ketone, vinyl chloride, vinylidene chloride, vinyl acetate, vinyl pyridine, vinyl pyrrolidone, vinyl trisalkoxysilane. However, the present invention is not limited to these.

The monomer having the crosslinkable functional group and the other compound may be copolymerized with the monomer serving as the basic skeleton at an arbitrary ratio to copolymerize two or more kinds of monomers.

In the present invention, the acrylic resin having the above-mentioned crosslinkable functional group and having a different glass transition point is used.
It is particularly preferable to use a mixture of at least one kind of acrylic resin because the adhesion to the sublimation type ink layer under normal temperature and normal humidity and high temperature and high humidity is further improved. Regarding the glass transition point of the acrylic resin used here, it is preferable that at least one has a glass transition point of 50 ° C. or higher, preferably 60 ° C. or higher, from the viewpoint of adhesion with the sublimation type ink layer under high temperature and high humidity,
It is preferable that the other acrylic resin to be mixed, whose glass transition point is lower than that of the other one, improves the adhesion to the sublimation type ink layer under normal temperature and normal humidity. That is, it is more preferable to use two or more kinds of acrylic resins having different glass transition points as described above in order to obtain high adhesiveness both under normal temperature and normal humidity and under high temperature and high humidity. The mixing ratio of the acrylic resin (A) having a glass transition point of 50 ° C. or higher and the acrylic resin (B) having a glass transition point of less than 50 ° C. is not particularly limited, but (A) / (B) is preferably a weight ratio. It is desirable that it is 95/5 to 5/95.

The glass transition point of the acrylic resin can be arbitrarily set depending on the monomer used. For example, in order to obtain a polymer having a high glass transition point, the copolymerization amount of methyl methacrylate is increased to obtain a resin having a low glass transition point. For this purpose, copolymerization of long-chain alkyl acrylate is effective. Further, it is particularly preferable that the acrylic resin has a molecular weight of 450,000 or more because the toughness of the easily adhesive coating increases.

In the present invention, heat treatment at a high temperature is possible when an easily-adhesive coating film is provided by a method of coating on a polyester film before completion of crystal orientation and stretching and heat treatment to complete crystal orientation. It is particularly preferable because a uniform, thin and easily adhesive coating film can be obtained. When the easily adhesive coating film is laminated by the above method, the acrylic resin is preferably soluble in, emulsified or suspended in water from the viewpoint of environmental pollution and explosion proof, and such a copolymer is a monomer having a hydrophilic group. It can be prepared by a known method such as copolymerization with (acrylic acid, methacrylic acid, acrylamide, vinyl sulfonic acid and salts thereof), emulsion polymerization using a surfactant, suspension polymerization, soap-free polymerization and the like.

In the present invention, the main point is to provide an easy-adhesion layer whose main component is a mixed coating material of the acrylic resin and polyethyleneimine. That is, it was found that the adhesiveness and the moisture-resistant adhesiveness are remarkably improved by using polyethyleneimine together with the acrylic resin. Of course, if the above-mentioned method of coating the polyester film before crystal orientation is used, the effect becomes particularly remarkable. Polyethyleneimine may be mixed in any weight ratio with respect to the acrylic resin, but in order to bring out the effect of the present invention more remarkably, 0.1 to 100 parts by weight, preferably 1 It is desirable that the amount is ˜50 parts by weight, more preferably 3 to 20 parts by weight.

The easily-adhesive coating film of the present invention is a coating film obtained by applying and curing a coating material containing the above-mentioned two types of constituent components as main components, and the main components are 50 types in the coating film. It means that it accounts for at least wt%, preferably at least 80 wt%, more preferably at least 90 wt%.

In the easily-adhesive coating film, known additives such as a heat stabilizer, an oxidation stabilizer, a weather stabilizer, an ultraviolet absorber, an organic lubricant, etc. may be added within a range that does not impair the effects of the present invention. Pigments, dyes, organic or inorganic fine particles, fillers, antistatic agents, nucleating agents and the like may be added.

The preferred method of laminating the easily adhesive coating is most preferably a method of applying the polyester film during the production process of the polyester film and stretching it together with the substrate. For example, a melt-extruded polyester film before crystal orientation is stretched about 2.5 to 5 times in the longitudinal direction, the surface to be continuously applied is subjected to corona discharge treatment, and the coating agent is applied to the treated surface. The applied film is dried while passing through a zone that is heated stepwise and stretched in the width direction by about 2.5 to 5 times. Further, it is obtained by a method of continuously introducing the material into a heating zone of 150 to 250 ° C. to complete the crystal orientation. The coating liquid used in this case is preferably an aqueous system from the viewpoint of environmental pollution and explosion proof.

The easily adhesive layer provided by such a method has less dyeing of the sublimation type ink layer formed thereon by the sublimable dye, and is excellent in reproducibility of color density and gradation at the time of printing. It has the effect of becoming one. The thickness of the coating film is not particularly limited, but is usually 0.01 to 5 μm, preferably 0.1.
03-2 μm, more preferably 0.05 μm-0.5 μ
A range of m is desirable. If the thickness of the easy-adhesion layer is too large, the dye may migrate to the easy-adhesion layer side, and the original gradation and color density may not be obtained. As a method of coating on the base material film, a known coating method, for example, a reverse coating method, a gravure coating method, a rod coating method, a die coating method or the like can be used.

Next, it is necessary to provide a stick preventing layer on the surface of the polyester film opposite to the surface provided with the easy adhesion layer in order to prevent fusion (sticking) between the polyester film and the thermal head. As the antistick layer, known materials such as silicone compounds, fluorine compounds and their modified products, copolymers, organic and inorganic lubricants can be used.

The sublimation type ink layer composition is not particularly limited, and known ones can be used. For example, binders that disperse dyes include celluloses, polyvinyl alcohol, and polyamide, and sublimable dyes include various disperse dyes and basic dyes. The thickness of the sublimation type ink layer is not particularly limited, but is usually 0.5 to 15 μm, preferably 1 to 7 μm.

Next, the method for producing the sublimation type thermal transfer material of the present invention will be explained, but the method is not necessarily limited to this. PET having an intrinsic viscosity of 0.63 dl / g containing so-called precipitated particles and inorganic particles (for example, silica particles having an average particle size of 1 μm) precipitated during the polymerization step is vacuum dried according to a conventional method, and then melt extruded to obtain a sheet-like melt. Is cooled and solidified on a cast drum at about 60 ° C. to prepare an unstretched PET film. A corona discharge treatment is applied to one surface of this film in air, and a coating agent for forming an easy-adhesion layer is applied. While holding this coated film with a clip,
After being introduced into a drying zone heated to 0 ° C., or after being dried, it is stretched 2.5 to 5.0 times in the width direction, and then 16
Heat treatment is performed in a heat treatment zone of 0 to 240 ° C. for 1 to 10 seconds to complete the crystal orientation of the PET film. If necessary, a relaxation treatment of 3 to 12% may be performed during this heat treatment. A stick-preventing layer is provided on the surface of the thus obtained laminated PET film opposite to the easy-adhesion layer, and then a sublimation-type ink is applied on the easy-adhesion layer and slit to an appropriate width to sublimate the heat-sensitive transfer of the present invention. Get the wood. The obtained sublimation-type heat-sensitive transfer material is suitable for use mainly in applications requiring photographic gradation, such as video printers.

[0031]

[Characteristic measuring method and effect evaluating method] The characteristic value measuring method and effect evaluating method of the invention are as follows.

(1) Sublimation type ink adhesion at room temperature and normal humidity Sublimation type ink is applied using a bar coater so that the thickness after drying is 5 μm. After coating, dry at 120 ° C for 2 minutes, leave at 25 ° C and 60% RH for 24 hours, then apply cellophane tape (manufactured by Nichiban Co., Ltd.) on the sublimation-type ink layer with a sticker and then rapidly in 180 ° direction. Peel off.
At this time, the remaining area of the sublimation type ink layer remaining on the transfer material side is measured, and if the remaining area is 90% or more, the adhesion is good.

(2) Sublimation type ink adhesion under high temperature and high humidity A sublimation type ink layer is provided in the same manner as in the above (1), and 60 ° C.
Leave at 85% RH for 100 hours, and take out at room temperature for 5 hours.
Within minutes, the adhesion was evaluated by the same method as the above (1).

(3) Gradation and overtransfer The sublimation type thermal transfer material prepared in the above (1) was used as a sharp color video printer GZ-P11W type (Sharp Corp.).
The transfer test was conducted under standard conditions. The receiving paper attached to the printer was used, and the reproducibility of color tone (gradation) and the state of overtransfer were visually observed.

(4) Glass transition point Acrylic resin in the resin for forming an easy-adhesion layer is used as a differential scanning calorimeter (PERKIN ELMER DSC-2 type (PERK).
IN ELMER) at a temperature rising rate of 20 ° C./min.

[0036]

EXAMPLES Next, the present invention will be explained based on examples.

Example 1 0.15% by weight of precipitated particles having a particle diameter of 0.5 to 1.5 μm (particles precipitated in the polymerization step) and 0.2 of calcium carbonate particles having an average particle diameter of about 1.5 μm. PET pellets containing 100% by weight (intrinsic viscosity 0.63 dl / g) were sufficiently vacuum dried, then fed to an extruder and melted at 280 ° C.,
Extruded into a sheet from the T-shaped die, and the surface temperature was 60
It was wound around a mirror-finished drum at ℃ and cooled and solidified. This unstretched sheet was heated to 95 ° C. and stretched 3.5 times in the longitudinal direction to obtain a uniaxially stretched film. One side of this film was subjected to a corona discharge treatment in air and coated with the following "adhesive layer forming coating agent". The coating thickness was such that the easy adhesion layer had a thickness of 0.1 μm after completion of crystal orientation. The applied coating agent is shown below.

"Easy-adhesion layer-forming coating agent" (a) Acrylic resin having a glass transition point of 35 ° C. and composed of a copolymer of methyl methacrylate / butyl acrylate / acrylic acid / N-methylol acrylamide: 95 parts by weight (b) Polyethyleneimine : 5 parts by weight The above two types were mixed to prepare an aqueous coating agent diluted to 3% by weight with water.

The coated uniaxially stretched film was held by a clip, introduced into a preheating zone heated at 110 ° C. to dry the water, and continuously stretched 4.5 times in the width direction in a heating zone at 130 ° C. Then, heat treatment was performed in a heating zone of 225 ° C. for 2 seconds to prepare a laminated PET film having crystal orientation completed. A stick-preventing layer containing silicone as a main component was applied to the surface of the film opposite to the easy-adhesion layer side and dried, and then the following "sublimation ink" had a thickness of 5
It was applied so as to have a thickness of μm and slit to obtain a sublimation-type heat-sensitive transfer material.

"Sublimation ink" composition Disperse dye KST-B-136 (manufactured by Nippon Kayaku Co., Ltd.): 4
Parts by weight Ethyl hydroxyethyl cellulose: 6 parts by weight Methyl ethyl ketone: 45 parts by weight Toluene: 45 parts by weight

This sublimation type heat-sensitive transfer material exhibits good adhesion (5% or less of the peeled portion) under normal temperature and normal humidity and under high temperature and high humidity, and has good color reproducibility and no overtransfer. It was

Comparative Example 1 In the case where the laminated PET film having no easy-adhesion layer was prepared in Example 1 and the sublimation type ink layer was laminated on the PET surface, the sublimation type ink layer was peeled off 100% at room temperature, and it was measured by a printer. Significant overtranscription occurred in the transcription test.

Example 2 A sublimation-type heat-sensitive transfer material was obtained in the same manner as in Example 1 except that the "easy-adhesion layer-forming coating material" had the following composition.

"Easy-adhesion layer-forming coating agent" (a) Acrylic resin having a glass transition point of 35 ° C. and made of a copolymer of methyl methacrylate / butyl acrylate / acrylic acid / N-methylol acrylamide: 75 parts by weight (b) Methyl methacrylate / Ethyl acrylate / acrylic acid / N-methylol acrylamide copolymer having a glass transition point of 72 ° C. Acrylic resin: 20 parts by weight (c) Polyethyleneimine: 5 parts by weight The above three types are mixed and 3% by weight with water. An aqueous coating solution diluted to 1 was prepared.

This sublimation-type heat-sensitive transfer material exhibits extremely excellent adhesion (at a peeled portion of 1% or less) under normal temperature and normal humidity as well as under high temperature and high humidity, and has no problem in color tone reproducibility and overtransfer. there were.

Comparative Example 2 Polyethyleneimine of Example 1 was not used, but an acrylic resin alone was used in the same manner. The sublimation-type ink layer laminated on this easy-adhesion layer peeled at about 50% at room temperature and 100% at high temperature and high humidity.

Comparative Example 3 As the acrylic resin of Example 1, methyl methacrylate /
A sublimation-type heat-sensitive transfer material was prepared in the same manner except that an acrylic resin having a glass transition point of 32 ° C. (65 parts by weight) composed of butyl acrylate / ethyl acrylate was used. Since this easy-adhesion layer does not have a crosslinkable functional group, its adhesion to ink is extremely weak, and about 70% of it peeled off at room temperature.

[0048]

The sublimation type heat-sensitive transfer material produced by the present invention has the following excellent effects.

(1) The adhesion to the sublimation type ink layer is extremely excellent, and the ink layer does not peel off even at room temperature and high temperature and high humidity.

(2) Excellent color tone reproducibility and no overtransfer.

Claims (2)

[Claims] 1. A sublimation-type heat-sensitive transfer material, wherein a sublimation-type ink layer is provided on one surface of a polyester film via an easy-adhesion layer, and a stick-prevention layer is provided on the surface opposite to the surface provided with the easy-adhesion layer. The easily adhesive layer has at least 1 in the molecule.
A sublimation-type thermal transfer material comprising an acrylic resin having at least one kind of crosslinkable functional group and polyethyleneimine as main constituent components. 2. An acrylic resin having different glass transition points.
The sublimation-type thermal transfer material according to claim 1, wherein the sublimation-type thermal transfer material is a mixture of at least one kind of acrylic resin and has a glass transition point of 50 ° C or higher.