JP2001105745A - Image-receiving body for heat-sensitive transfer recording and its manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image-receiving body for a heat-sensitive transfer recording, wherein the separation property to a heat-transfer sheet containing a sublimation dye is excellent, the coloring density is high, and a recorded image which is excellent in clearness can be formed, and its manufacturing method. SOLUTION: For this image-receiving body for a heat-sensitive transfer recording, a dye-accepting layer comprises a cyclic ester modified cellulose derivative which is obtained by ring-opening-polymerizing a cyclic ester with a hydroxyl group-containing cellulose derivative. In this case, the dye-accepting layer is formed by applying the cyclic ester modified cellulose derivative solution which is obtained by ring-opening-polymerizing the cyclic ester with the hydroxyl group-containing cellulose derivative, at least on one surface of a base material, in this manufacturing method of the image-accepting body for the heat-sensitive transfer recording.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image receiving body for thermal transfer recording, and more particularly, to an image receiving body for thermal transfer recording, which is excellent in releasability from a thermal transfer sheet containing a sublimable dye, has a high color density, and is sharp. The present invention relates to a thermal transfer recording image receiving member capable of forming a recorded image excellent in image quality and a method for producing the same.

[0002]

2. Description of the Related Art Various methods of thermal transfer of an image have been conventionally known. For example, a thermal transfer sheet in which a recording agent such as a sublimable dye is supported on a base sheet (for example, a polyester film or the like); A method is proposed in which an image-receiving sheet having a dye-receiving layer formed thereon is brought into contact with a transfer-receiving material (eg, paper or plastic film) dyeable with a sublimable dye, and various full-color images are formed on the image-receiving sheet by heating. Have been.

In this method, a thermal head of a printer is used as a heating means, and a large number of color dots of three or four colors are transferred to an image receiving sheet by heating for an extremely short time, and a full-color image of an original is formed by the large number of color dots. Has been reproduced. The image formed in this manner is very clear because the coloring material used is a dye, and has excellent transparency, so that the obtained image has excellent intermediate color reproducibility and gradation, High image quality comparable to a full-color photographic image can be formed.

In the thermal transfer method, not only the configuration of the thermal transfer sheet but also the configuration of an image receiving sheet for forming an image is important. Examples of the thermal transfer recording image receiving sheet include polyester-based resins, halogen-containing vinyl resins such as polyvinyl chloride resins, polycarbonate resins, polyvinyl butyral resins, acrylic resins, cellulose resins, olefin resins, and styrene resins. Sheets formed with a dye receiving layer using a resin or the like are known. Means for improving the dyeability of the sublimable dye to be transferred in such a thermal transfer image-receiving sheet include a method of forming a dye-receiving layer using a resin having good dyeability.

For example, Japanese Patent Application Laid-Open No. Sho 62-21195 discloses a heat transfer recording recording medium comprising a mixture containing an easily dyeable resin such as polyester, epoxy resin and polystyrene and a pigment and having an image receiving layer having a high surface smoothness. An image receiving sheet has been proposed. In this method, it is described that the easily dyeable resin may be a water-soluble resin or an emulsion resin. However, a resin having good dye-dyeing properties has a low softening point. When the dye-receiving layer of a thermal transfer recording image-receiving sheet is formed of such a resin, the heat of a thermal head during image formation causes the dye-receiving layer and the thermal transfer sheet to have a low softening point. When the two are peeled off from each other and the two are peeled off, there is a problem (so-called abnormal transfer) that the dye layer of the thermal transfer sheet is transferred to the image receiving sheet due to the fusion. Further, as a method for improving the dyeing property of the dye, there are a method of including a plasticizer in the dye-receiving layer, a method of improving the diffusibility of the dye for thermal transfer, and the like. However, the formed image bleeds during storage, and the storability of the image is low.

Japanese Unexamined Patent Publication (Kokai) No. 62-222895 discloses that a dyeing layer of a sublimation type thermosensitive recording image receiving material comprises an acrylic polymer and a surface modifier having a graft or block structure of fluorine or silicone. An image receptor containing is disclosed.

JP-A-6-24152 discloses that a dye-receiving layer of a sublimation transfer recording image receiver has a core-shell structure formed of a polyester resin having at least one polar group and a polymer of a polymerizable unsaturated compound. It has been proposed to form a composite polymer aqueous dispersion. However, it is difficult for these image receivers to improve the color density and the sharpness of an image while improving the releasability from the thermal transfer sheet. When the dyeing property of the dye receiving layer is improved in this way, the releasability decreases, and the dyed dye forms a receiving layer with a resin that does not easily migrate in the dye receiving layer, and improves the releasability and storage stability. In addition, the dyeability of the dye is low, and an image with high density and high sharpness cannot be formed.

[0008]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a thermal transfer method using a sublimable dye, which is excellent in releasability (release property) from a thermal transfer sheet in an image forming process or thermal transfer and has a high color density. An object of the present invention is to provide an image receiving body for thermal transfer recording capable of forming a recorded image having high sharpness and excellent sharpness, and a method for producing the same.

[0009]

Means for Solving the Problems The inventors of the present invention have made intensive studies to achieve the above object, and as a result, when the dye receiving layer of the image receiving body for thermal transfer recording is formed of a cyclic ester-modified cellulose derivative, The image receiving body has excellent releasability from the thermal transfer sheet during thermal transfer, and has a high color density,
The present inventors have found that a recorded image having excellent sharpness can be formed on an image receiving member, and have completed the present invention.

That is, the present invention provides a thermal transfer recording image receptor in which the dye receiving layer of the thermal transfer recording image receptor comprises a cyclic ester-modified cellulose derivative obtained by ring-opening polymerization of a hydroxyl group-containing cellulose derivative with a cyclic ester. I do. In the above invention, there is provided an image receiving body for thermal transfer recording, wherein a dye receiving layer is coated on at least one surface of a substrate. Further, the present invention provides a thermal transfer recording image receiver in which the hydroxyl group-containing cellulose derivative is cellulose acetate and a thermal transfer recording image receiver in which the cyclic ester is ε-caprolactone. Furthermore, the present invention provides a method for producing an image receiving body for thermal transfer recording, wherein a solution of a cyclic ester-modified cellulose derivative obtained by ring-opening polymerization of a cyclic ester with a hydroxyl group-containing cellulose derivative is applied to at least one surface of a substrate. .

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail.
Cyclic ester modified cellulose derivative used in the present invention,
It is obtained by grafting a cyclic ester to a hydroxyl group-containing cellulose derivative. The hydroxyl group-containing cellulose derivative used as a raw material is a cellulose derivative having a remaining hydroxyl group obtained by esterifying or etherifying a part of the hydroxyl group of cellulose.

Examples of the hydroxyl group-containing cellulose derivative include, for example, cellulose esters such as cellulose acetate, cellulose acetate butyrate, cellulose acetate propionate, cellulose acetate phthalate, and cellulose nitrate; or ethyl cellulose, methyl cellulose, hydroxy cellulose, and hydroxypropyl. Examples include cellulose ethers such as methyl cellulose. Among them, good solubility in cyclic esters, relatively inexpensive, because it is industrially available,
Cellulose fatty acid esters are preferably used in the present invention, and cellulose acetate, cellulose acetate butyrate, and cellulose acetate propionate are preferable because they are easier to handle.

Particularly preferably, the degree of acetyl group substitution is 1.5.
Cellulose acetate having a degree of propionyl group substitution of 0.5 to 2.8 (propionylation degree of 12 to 63%) and a degree of acetyl group substitution of 0.5 to 2.
Cellulose acetate propionate having a acetylation degree of 8 to 16 (butyrylation degree: 14 to 67%);
It is a cellulose acetate butyrate having a 2.8 (degree of acetylation of 16 to 60%).

In the present invention, the cyclic ester used for the modification with the cyclic ester, that is, graft polymerization to the hydroxyl group of the hydroxyl group-containing cellulose derivative, may be any one capable of ring-opening polymerization, for example, β-propiolactone. , Δ-valerolactone, ε-caprolactone, α, α
-Dimethyl-β-propiolactone, β-ethyl-δ-
Valerolactone, α-methyl-ε-caprolactone, β
Lactones such as -methyl-ε-caprolactone, γ-methyl-ε-caprolactone, 3,3,5-trimethyl-ε-caprolactone, enantholactone; glycolide;
Examples thereof include cyclic dimers of hydroxycarboxylic acids such as lactide. These may be used in combination. In particular, it is industrially available and relatively inexpensive,
It is advantageous to use ε-caprolactone, which has excellent compatibility with cellulose derivatives such as cellulose acetate.

In the present invention, the ratio of the hydroxyl group-containing cellulose derivative to the cyclic ester is not particularly limited, but in general, the modification with the cyclic ester is carried out in an amount of 1 to 85% by mass, more preferably 30 to 70% by mass. And 15 to 99% by mass of the cyclic ester, more preferably 30 to 70% by mass. When the charging ratio of the hydroxyl group-containing cellulose derivative is more than 85% by mass, the viscosity of the reaction system becomes extremely high, and it becomes difficult to handle. If the proportion of the hydroxyl group-containing cellulose derivative is less than 1% by mass, the productivity is reduced. When the viscosity is particularly high, a reacting processing device using a twin-screw extruder or the like may be used together with a monomer vacuum distillation recovery device as necessary.

When the viscosity is high, if necessary, the viscosity of the organic solvent which does not have active hydrogen having good compatibility with cellulose acetate and the cyclic ester as the third component and the viscosity of the system is reduced to a range which is easy to handle. It is also possible to react. Examples of these solvents include ketone-based and ester-based solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone, ethyl acetate, butyl acetate, and cellosolve acetate, and mixed solvents thereof.

In general, hydroxyl-containing cellulose derivatives include:
The catalyst used in the reaction for graft polymerization of cyclic esters is typically a catalyst used for ring-opening reaction of cyclic esters, that is, a derivative such as an alkali metal such as sodium or potassium and its alkoxide, and tetrabutyl titanate. Organometals such as alkoxide titanium compounds, tin octylate, dibutyltin laurate; and metal halides such as tin chloride, which are generally widely described in the literature.

However, the preferred catalyst used in the present invention is tin octylate. The reaction time varies depending on the type of the hydroxyl group-containing cellulose derivative and the cyclic ester, and the charge ratio, the type and amount of the catalyst, the reaction temperature, and furthermore, the reaction temperature, and is not particularly limited, but is preferably 1 hour to 8 hours. It is. In particular, when a reacting processing apparatus such as a twin-screw extruder is used together with a vacuum distillation and recovery apparatus for unreacted monomers, the reaction time is reduced to 10 hours.
It is also possible to achieve the purpose by making it extremely short, such as less than a minute.

In obtaining the graft polymer used in the present invention, it is preferable that the raw materials used, nitrogen for purging the reactor, the reactor, and the like be sufficiently dried.
The water content of the reaction system is 0.1% by mass or less, preferably 0.00
1% by mass or less. The polymerization temperature is usually preferably the temperature applied to the ring-opening polymerization of the cyclic ester,
10 ° C. is preferred.

The molecular weight of the thus obtained cyclic ester-modified cellulose derivative also depends on the molecular weight of the starting cellulose ester having a hydroxyl group and the type of the cyclic ester to be grafted. Mass average molecular weight (formerly referred to as weight average molecular weight) of 50,000-100
Those having a range of 10,000 are preferably used. Further, a raw material hydroxyl-containing cellulose derivative and a cyclic ester (for example, ε-
The average graft polymer obtained by polymerizing the proportion of (caprolactone) within the above range is as follows:
ε-caprolactone has a structure formed by addition polymerization of 1 to 50 mol, preferably 2 to 30 mol, more preferably 2 to 20 mol.

A cyclic ester-modified cellulose derivative solution is applied to a substrate to form a dye-receiving layer to obtain an image receptor for thermal transfer recording. As the base material of the image receiving body, for example, natural paper, synthetic paper (eg, polypropylene-based, polystyrene-based, polyester-based synthetic paper, etc.), plastic film (eg, a polyester film such as a polyethylene terephthalate film), or a laminate thereof A body or the like can be used. Preferred substrates include synthetic papers and plastic films.

The thickness of the substrate may be, for example, 5
The range can be selected from a range of about 500 to 500 μm, preferably about 10 to 300 μm, and more preferably about 50 to 200 μm. To the base material, especially synthetic paper or plastic film, if necessary, for example, additives such as antioxidants, ultraviolet absorbers, stabilizers such as heat stabilizers, lubricants, antistatic agents, and pigments are added. Is also good. The image receiver has a dye receiving layer containing the resin on at least one surface of the substrate. The receiving layer is formed by applying a coating solution containing a resin to a substrate and drying the coating solution. This coating liquid can be prepared by using a suitable solvent for the resin composition. As a method of applying the coating liquid, a conventional method, for example, a roll coating method such as gravure or reverse, a doctor knife method, a knife coating method,
A nozzle coating method can be adopted. The dye receiving layer of the image receiving body may be a single layer or a laminate, and is usually a single layer. The thickness of the receiving layer is, for example, 0.1 μm or more (for example, 0.5 to 40 μm) depending on the substrate and the purpose of use.
μm), and more preferably from about 1 to 30 μm. The cyclic ester-modified cellulose derivative accounts for 5 to 50% by mass, more preferably 10 to 4% by mass, based on the solid content of the receiving layer.
0% by mass is preferred. The image receiving body of the present invention is used in combination with a thermal transfer sheet containing a sublimable dye. The image receiving body of the present invention is a thermal transfer method, for example, the image receiving body is brought into contact with a thermal transfer sheet containing a sublimable dye, and heated by using a thermal head or the like to transfer the thermal transfer dye to the image receiving body. Useful for forming an image on a receiver.

[0023]

EXAMPLES The present invention will now be described specifically with reference to examples, but the present invention is not limited to these examples. still,
“Parts” are based on mass%. The evaluation method is as follows. (Evaluation of Printed Image Density): A sublimation type digital color printer DPP-M1 (manufactured by Sony Corporation) is used to print on the image receiving body (image receiving sheet), and the color density is measured using a reflection type Macbeth densitometer RD-125.
5 (manufactured by Saika Inx). The ink ribbon used was a printer pack VPM-P50STA dedicated to DPP-M1. Printing conditions are Macintosh (Apple)
Printer driver (Sony) standard setting. (Evaluation of Peelability): At the time of peeling of the ink ribbon from the image receiving sheet during printing, the occurrence of abnormal transfer due to thermal fusion or the like was visually observed.

(Example 1) (Polymerization of graft polymer) A stirrer, a thermometer, a reflux condenser, and a sufficiently dried reactor were placed in a dry nitrogen atmosphere at 50 parts of ε-caprolactone. Cellulose acetate (made by Daicel Chemical, degree of acetylation 5
5.2%, degree of substitution 2.43) 100 parts with stirring
After adding at 80 ° C. and dissolving uniformly, 0.12 parts of tin octylate was charged and the reaction was continued for 3 hours. Thus, a slightly yellow transparent graft polymer was obtained. When the intrinsic viscosity of the graft polymer at 50 ° C. was determined using acetone, [η] = 0.75 dl / g. (Preparation of sublimation transfer recording image-receiving sheet) 20 parts of the above graft polymer was dissolved in 80 parts of acetone, and
Using a wire bar on a 50 μm polypropylene synthetic paper (Yopo FPG-150, manufactured by Oji Yuka Synthetic Paper Co., Ltd.)
The coating was applied so as to obtain a dry coating film of 0 μm, and dried at 110 ° C. for 10 minutes to obtain a thermal transfer recording image receiver having a dye receiving layer. The evaluation result of print image density
Color density = 5.5 (sum of the maximum values of the reflection densities of cyan, magenta, yellow, and black), and a high color density was obtained. In addition, visual observation of peelability showed high peelability without abnormal transfer due to thermal fusion or the like.

(Example 2) In the same manner as in Example 1, ε
Polymerization was carried out while changing the charged amount of caprolactone to 70 parts. The obtained graft polymer was treated with acetone for 5 minutes.
When the intrinsic viscosity at 0 ° C. was determined, [η] = 0.52 dl / g
Met. Example 1 was prepared using the obtained graft polymer.
An image receiving sheet was prepared in the same manner as in Example 1 and examined in the same manner as in Example 1. As a result, the color density was 5.5, and a high color density was obtained. Further, when the releasability was evaluated, high releasability was exhibited without occurrence of abnormal transfer due to thermal fusion or the like.

[0026]

According to the present invention, by using a thermal transfer recording image receiving member formed of a cyclic ester-modified cellulose derivative as shown in the examples, it is possible to maintain a peeling property and obtain a printed image having a high color density. .

Claims (5)

[Claims] The dye-receiving layer of the image-receiving member for thermal transfer recording,
An image receiving body for thermal transfer recording comprising a cyclic ester-modified cellulose derivative obtained by ring-opening polymerization of a cyclic ester with a hydroxyl group-containing cellulose derivative. 2. The image receiving body for thermal transfer recording according to claim 1, wherein a dye receiving layer is coated on at least one surface of the substrate. 3. The image receiving body for thermal transfer recording according to claim 1, wherein the hydroxyl group-containing cellulose derivative is cellulose acetate. 4. The image receiving body for thermal transfer recording according to claim 1, wherein the cyclic ester is ε-caprolactone. 5. A heat-sensitive transfer recording image-receiving method comprising forming a dye-receiving layer by applying a cyclic ester-modified cellulose derivative solution obtained by ring-opening polymerization of a cyclic ester to a hydroxyl group-containing cellulose derivative on at least one surface of a substrate. How to make the body.