JP7181018B2 - Sublimation-type thermal transfer image-receiving sheet and manufacturing method thereof - Google Patents

Description

TECHNICAL FIELD The present invention relates to a sublimation-type thermal transfer image-receiving sheet and a method for producing the same.

Currently, there is a thermal transfer recording method as one of printing methods capable of reproducing clear patterns. The thermal transfer recording method can be broadly classified into a sublimation thermal transfer method using a thermal sublimation dye and a thermal fusion transfer method using a thermal fusion dye. In the sublimation thermal transfer method, the dye once changes from solid to gas and then to solid. Further, in the hot-melt transfer method, the dye once changes from solid to liquid and then to solid. Of these transfer methods, the sublimation thermal transfer method has the advantage of being able to handle small lots, and the advantage of being able to divide the raw dots and change the transfer area (making it possible to express detailed gradation). . Therefore, according to the sublimation thermal transfer method, it is possible to print clear patterns with higher resolution than in the case of the thermal melting transfer method.

Therefore, in recent years, the demand for the sublimation thermal transfer method is increasing rather than the hot melt transfer method. In general, the sublimation thermal transfer method uses a combination of an ink ribbon using a thermal sublimation dye and a sublimation thermal transfer image receiving sheet to which the ink ribbon adheres during printing. Therefore, the sublimation thermal transfer image receiving sheet is required to be less susceptible to heat, to adhere only to a designated printing range with an ink ribbon, and to have good printability such as transfer density. Also, the adhesion of the sublimation-type thermal transfer image-receiving sheet to the ink ribbon must be accompanied by releasability. If the releasability is low, there is a possibility that the delamination noise during printing becomes louder, or that the sublimation thermal transfer image-receiving sheet cannot be discharged from the printing machine. In particular, in the sublimation thermal transfer method, since an image is usually formed by a subtractive color method, yellow, magenta, and cyan dyes are sequentially printed on the thermal transfer image-receiving sheet. Therefore, the thermal transfer image-receiving sheet is subjected to at least three printing processes, and it is not enough for the releasability to be excellent only once, and excellent releasability is maintained in all of at least three printing processes. It is required to have sufficient peel stability.

Against this background, Patent Document 1 discloses a thermal transfer image-receiving sheet having a base sheet and a receiving layer containing a binder resin, a high-molecular-weight silicone, and a low-molecular-weight modified silicone formed on the base sheet. Therefore, a thermal transfer image-receiving sheet in which the kinematic viscosities of high-molecular-weight silicone and low-molecular-weight modified silicone are specified is proposed.

In recent years, however, sublimation thermal transfer image-receiving sheets are increasingly used after being cut into shapes suitable for applications such as business cards, IC cards, electronic tags, employee ID cards and certificates. However, the thermal transfer image-receiving sheet proposed in the above document, which emphasizes releasability, tends to generate burrs when cut into an appropriate shape, and a solution to this problem is desired.

JP 2007-90650 A

A main problem to be solved by the present invention is to provide a sublimation-type thermal transfer image-receiving sheet which is free from burrs when cut, and a method for producing the same.

The inventors of the present invention conducted various studies to solve the above problems. As a result, we found that the adhesion between the base paper and the ink-receiving layer is important for the problem of burrs. Therefore, the thermal transfer image-receiving sheet of Patent Document 1, which emphasizes releasability, may cause burrs. However, more importantly, the problem of burrs cannot be solved only by considering adhesion, or adhesion and peelability. Absorbability (cushioning properties) of the force applied when the thermal transfer image-receiving sheet is cut is also important in solving the problem of burrs. Based on such findings, the following means for solving the above problems have been conceived.

(Means according to claim 1)
having a base paper and an ink-receiving layer formed on one or both sides of the base paper,
The base paper is a cast-coated paper in which the undercoat layer is a coat layer ,
This cast-coated paper has an arithmetic mean roughness of 0.10 to 0.60 μm measured according to JIS B 0601 (2013) and a density of 0.80 measured according to JIS P 8118 (2014). ~1.20 g/ ^cm3 ,
The undercoat layer has a plurality of layers, and at least the outermost layer in contact with the ink-receiving layer contains hollow particles formed by a rewet casting method,
The ink-receiving layer contains a base agent, a release agent, and a polyolefin-based resin, and the content of the polyolefin-based resin is 0.50% by mass or more.
A sublimation-type thermal transfer image-receiving sheet characterized by:

(Means according to claim 2)
The release agent is a silicone resin,
The content of the silicone-based resin in the ink-receiving layer is 0.10% by mass or more, and the content of the polyolefin-based resin is 300 to 2910 parts by mass with respect to 100 parts by mass of the silicone-based resin.
The sublimation-type thermal transfer image-receiving sheet according to claim 1.

(Means according to claim 3)
The ink-receiving layer has a thickness of 1 to 80 μm and a content of the polyolefin resin of 15.0% by mass or less.
The sublimation-type thermal transfer image-receiving sheet according to claim 1 or 2.

(Means according to claim 4)
The base agent is a vinyl chloride-vinyl acetate copolymer resin, and vinyl chloride: vinyl acetate = 85-95: 5-15 (by mass),
The sublimation-type thermal transfer image-receiving sheet according to any one of claims 1 to 3.

(Means according to claim 5)
The polyolefin resin has a chlorine content of 20 to 30% by mass.
The sublimation-type thermal transfer image-receiving sheet according to claim 4.

(Means according to claim 6)
The silicone-based resin is a diamine-modified silicone resin, and the functional group equivalent of diamine, which is an organic group, is 100 to 1800 g / mol.
The sublimation-type thermal transfer image-receiving sheet according to claim 2.

(Means according to claim 7)
The cast coated paper has a paper thickness of 66 to 188 μm measured according to JIS P 8118 (1998).
The sublimation-type thermal transfer image-receiving sheet according to any one of claims 1 to 6.

(Means according to claim 8)
The arithmetic mean roughness measured in accordance with JIS B 0601 (2013) is 0.00, measured according to JIS B 0601 (2013) after forming a multi-layered undercoat layer in which at least the outermost layer in contact with the ink-receiving layer contains hollow particles . Cast-coated paper having a thickness of 10 to 0.60 μm and a density of 0.80 to 1.20 g/cm ³ measured according to JIS P 8118 (2014),
An ink-receiving layer coating liquid is applied to the outermost layer of the cast-coated paper,
As the ink-receiving layer coating liquid, a coating liquid containing a base agent, a release agent, and a polyolefin-based resin and having a content of the polyolefin-based resin of 0.20% by mass or more is used.
A method for producing a sublimation-type thermal transfer image-receiving sheet, characterized by:

According to the present invention, a sublimation-type thermal transfer image-receiving sheet and a method for producing the same are provided which are free from burrs when cut.

1 is a cross-sectional view of a sublimation-type thermal transfer image-receiving sheet; FIG. 1 is a cross-sectional view of a sublimation-type thermal transfer image-receiving sheet having an undercoat layer; FIG.

Next, a mode for carrying out the invention will be described. Note that this embodiment is an example of the present invention. The scope of the present invention is not limited to the scope of this embodiment. In addition, unless otherwise stated, the content ratio, compounding ratio, content, and compounding amount of each drug described below mean the mass in terms of solid content. The content ratio of each drug in the ink-receiving layer means the content ratio excluding the residual component derived from the organic solvent, if any, in the ink-receiving layer.

As shown in FIG. 1, the sublimation-type thermal transfer image-receiving sheet (hereinafter also simply referred to as "thermal transfer image-receiving sheet") X of this embodiment includes a base paper 1 and one surface of the base paper 1 ((1 in FIG. 1). )) or an ink-receiving layer 2 formed on both surfaces (the form shown by (2) in FIG. 1). Preferably, an undercoat layer 3 is provided between the base paper 1 and the ink-receiving layer 2, as shown in FIG. In this specification, the undercoat layer 3 is included in the broad definition of base paper in relation to the ink-receiving layer 2 . That is, the base paper 1 constitutes a base paper in a narrow sense, and the base paper 1 and the undercoat layer 3 constitute a base paper in a broad sense. Therefore, in the present invention, where the relationship with the ink-receiving layer matters, the term "base paper" simply means base paper in a broad sense. However, hereinafter, for the convenience of explanation, simply referring to "base paper" means "base paper in a narrow sense" unless otherwise specified.

(base paper: pulp)
The (narrowly defined) base paper 1 contains pulp (hereinafter also referred to as “raw pulp”) as a main component (50.0% by mass or more, preferably 80.0% by mass or more). As raw material pulp, for example, virgin pulp, waste paper pulp, pulp combining these, and the like can be used.

Examples of virgin pulp include bleached hardwood kraft pulp (LBKP), bleached softwood kraft pulp (NBKP), unbleached hardwood kraft pulp (LUKP), unbleached softwood kraft pulp (NUKP), semi-bleached hardwood kraft pulp (LSBKP), Chemical pulp such as softwood semi-bleached kraft pulp (NSBKP), hardwood sulfite pulp, softwood sulfite pulp; stone ground pulp (SGP), pressure stone ground pulp (TGP), chemi-ground pulp (CGP), groundwood pulp (GP), Mechanical pulps (MP), such as thermomechanical pulp (TMP), and the like can be used alone or in combination.

Examples of waste paper pulp include defibered waste paper pulp produced from waste tea paper, waste kraft envelope paper, waste magazine paper, waste newspaper paper, waste flyer paper, waste office paper, waste corrugated board, white waste paper, Kent waste paper, imitation waste paper, and waste paper. , defiberized/deinked waste paper pulp (DIP), defibered/deinked/bleached waste paper pulp, etc. can be used singly or in combination.

(base paper: additive)
Additives such as fillers can be internally added to the base paper 1, if necessary. Examples of additives include fillers, sizing agents, paper quality improvers, coagulants, antifoaming agents, fluorescent whitening agents, aluminum sulfate, retention improvers, drainage improvers, dry strength enhancers, and wet strength enhancers. Agents, coloring dyes, coloring pigments, waterproofing agents, etc. can be used singly or in combination.

When a filler is internally added as an additive, its content is, for example, 5.0 to 15.0% by mass, preferably 7.0 to 10.0% by mass. If the content of the filler is less than 5.0% by mass, the flatness of the base paper 1 may deteriorate, making it difficult to form the ink-receiving layer 2 uniformly. In addition, when the undercoat layer 3 is provided, uniform formation of the undercoat layer 3 may become difficult, and formation of the ink-receiving layer 2 may also become difficult. On the other hand, if the content of the filler exceeds 15.0% by mass, the rigidity of the base paper 1 may be lowered and the curl resistance may be deteriorated. In addition, the pulp component is reduced, and the cushioning properties of the base paper 1 may also deteriorate. This reduction in cushioning properties may lead to the generation of burrs.

(base paper: basis weight)
The basis weight of the base paper in a broad sense (base paper 1 and undercoat layer 3 when provided with base paper 1 and undercoat layer 3) is preferably 80.0 to 150.0 g/m ² , and preferably 84.9 to 127 g/m 2 . More preferably 0.9 g/m ² . If the basis weight of the base paper in the broad sense is less than 80.0 g/m ² , the rigidity of the base paper in the broad sense may be lowered and the curl resistance may be deteriorated. On the other hand, when the basis weight of the base paper in the broad sense exceeds 150.0 g/m ² , the rigidity of the base paper in the broad sense increases, and when processed into a shape suitable for the application (business card, IC card, etc.) (when cutting) 2) processing defects may occur. The basis weight of base paper in a broad sense is a value measured according to JIS P 8124 (2011).

(base paper: density)
The broadly defined density of the base paper is preferably 0.80 to 1.20 g/cm ³ , more preferably 0.98 to 1.10 g/cm ³ . If the density of the broadly-defined base paper is less than 0.80 g/cm ³ , the unevenness of the surface of the broadly-defined base paper increases, which may make it difficult to form the ink-receiving layer 2 uniformly. On the other hand, when the density of the base paper in the broad sense exceeds 1.20 g/cm ³ , the cushioning properties (elasticity) of the base paper in the broad sense become insufficient, and the transfer density may be considered insufficient. be. Moreover, when the density of the base paper in a broad sense exceeds 1.20 g/cm ³ , the absorbability (cushioning property) of the force applied when the thermal transfer image receiving sheet X is cut is also lowered due to the deterioration of the cushioning property. As a result, the thermal transfer image receiving sheet X may be burred. In addition, the density of base paper in a broad sense is a value measured according to JIS P 8118 (2014).

The density of the broadly defined base paper can be adjusted using known devices such as machine calenders, super calenders, and thermal calenders.

(base paper: thickness)
The broadly defined thickness of the base paper (paper thickness) is preferably 66 to 188 μm, more preferably 80 to 110 mm. If the thickness of the base paper in the broad sense is less than 66 μm, the rigidity of the base paper in the broad sense may decrease, and the curl resistance may deteriorate. Moreover, if the thickness of the base paper in the broad sense is less than 66 μm, the cushioning property is lowered, so even if the density of the base paper in the broad sense is 1.20 g/cm ³ or less, the thermal transfer image-receiving sheet X may be burred. . On the other hand, if the thickness of the base paper in the broad sense exceeds 188 μm, the rigidity of the base paper in the broad sense increases, and processing defects may occur when processing into a shape suitable for the application (business card, IC card, etc.). The thickness of base paper in a broad sense is a value measured according to JIS P 8118 (1998).

(base paper: arithmetic mean roughness)
The broadly defined (surface) arithmetic mean roughness of the base paper is preferably 0.10 to 0.60 μm, more preferably 0.20 to 0.35 μm. If the arithmetic mean roughness of the broadly-defined base paper is less than 0.10 μm, the broadly-defined base paper needs to be calendered, for example, under high pressure conditions, resulting in the flattening of the surface of the broadly-defined base paper. , there is a possibility that the stiffness of the base paper in a broad sense is lowered and the curl resistance is deteriorated. On the other hand, when the arithmetic average roughness of the broadly defined base paper exceeds 0.60 μm, the ink receiving layer 2 formed on the broadly defined base paper also becomes rough, friction occurs upon contact with the ink ribbon, and heat insulating properties decrease. As a result, the ink transfer density may decrease. The arithmetic mean roughness of base paper in a broad sense is a value measured according to JIS B 0601 (2013).

The arithmetic mean roughness of the base paper in a broad sense is preferably adjusted by forming the undercoat layer 3 as the outermost layer by the cast coating method. In addition, for example, it can be adjusted using a device such as a machine calender, super calender, or thermal calender. Alternatively, the above methods can be combined for adjustment.

(Ink receiving layer)
The ink-receiving layer 2 is formed by applying an ink-receiving layer coating liquid containing at least a base agent, a release agent, an adhesion agent, and an organic solvent as a solvent.

(Ink-receiving layer: base agent)
The base agent is the component most responsible for the sublimation ink receptivity of the ink-receiving layer 2 or the ink-receiving layer coating liquid (hereinafter collectively referred to simply as "ink-receiving layer"). For this reason, the content is preferably 70.0% by mass or more.

As the base agent, a known resin material that readily accepts sublimation dyes can be used. Specifically, for example, polyolefin resins such as polypropylene, halogenated resins such as polyvinyl chloride and polyvinylidene chloride, polyvinyl acetate, vinyl chloride-vinyl acetate copolymers, ethylene-vinyl acetate copolymers, poly Vinyl resins such as acrylic acid esters, polyester resins such as polyethylene terephthalate and polybutylene terephthalate, polystyrene resins, polyamide resins, copolymer resins of olefins such as ethylene and propylene and other vinyl polymers, ionomers and cellulose diastase cellulose-based resins such as cellulose-based resins, polycarbonates, solvent-based resins such as acrylic-based resins, and the like can be used singly or in combination. However, it is preferable to use a vinyl chloride-vinyl acetate copolymer resin as the base agent because of its good receptivity for sublimation dyes and good compatibility with other components.

A vinyl chloride-vinyl acetate copolymer resin (hereinafter also simply referred to as "vinyl chloride-acetate resin") has both the toughness of vinyl chloride and the adhesiveness of vinyl acetate. Accordingly, when the ink receiving layer 2 contains a vinyl chloride-acetate resin, the curling is suppressed and the adhesion to the ink ribbon is improved, so that the ink transfer density is improved.

Vinyl chloride-acetate resins include not only copolymers of vinyl chloride and vinyl acetate, but also copolymers of vinyl chloride, vinyl acetate, and other monomers.

The vinyl chloride/vinyl acetate resin preferably has a vinyl chloride:vinyl acetate ratio of 85 to 95:5 to 15, more preferably 86 to 93:7 to 14, on a mass basis. If the content of vinyl chloride is less than the above range, the heat resistance and rigidity are lowered, which may deteriorate the ink transferability and curl resistance. On the other hand, if the vinyl chloride content exceeds the above range, the adhesiveness of the ink-receiving layer 2 is lowered, and thus the adhesiveness to the ink ribbon may be lowered and the ink transfer density may be lowered. Moreover, the decrease in adhesiveness of the ink-receiving layer 2 causes burrs, and there is a possibility that the prevention of such burrs cannot be compensated for by only adding a high amount of the adhesion agent, which will be described later.

In addition, if the content of vinyl chloride is increased to 85 to 95% by mass, and the chlorine content in the polyolefin resin that is the adhesion agent is 20 to 30% by mass, as described later, the compatibility between the resins will be reduced. is improved, the strength of the ink-receiving layer is further improved, and burrs are also reduced.

The degree of polymerization of the vinyl chloride-acetate resin is preferably 600-800, more preferably 700-780. If the degree of polymerization of the vinyl chloride resin is less than 600, the melting point of the vinyl chloride resin will be low and the fluidity will also be low. There is In this regard, the deterioration of the releasability can be dealt with by increasing the content of the release agent, which will be described later. Further, when the polymerization degree of the vinyl chloride-acetate resin is less than 600, there is a possibility that the coating suitability of the ink-receiving layer coating liquid may deteriorate. On the other hand, when the degree of polymerization of the vinyl chloride-acetate resin exceeds 800, the vinyl chloride-acetate resin has a high melting point and high fluidity, so it is necessary to heat more than necessary at the time of transfer, resulting in poor curl resistance. There is a risk. Moreover, there is a possibility that the coating suitability of the coating liquid for the ink-receiving layer may deteriorate.

The number average molecular weight of the vinyl chloride-acetate resin is preferably 35,000 to 55,000, more preferably 40,000 to 50,000. If the number-average molecular weight of the vinyl chloride-acetate resin is less than 35,000, sufficient adhesion to the ink ribbon may not be obtained, resulting in poor transfer. Moreover, the decrease in the adhesion of the ink receiving layer 2 causes burrs, and there is a possibility that the prevention of such burrs cannot be compensated for by only adding a high amount of the adhesion agent, which will be described later. On the other hand, if the number-average molecular weight of the vinyl chloride-acetate resin exceeds 55,000, it may adhere too closely to the ink ribbon, resulting in poor peeling. In this regard, the deterioration of the releasability can be dealt with by increasing the content of the release agent, which will be described later.

The glass transition temperature of the vinyl chloride-acetate resin is preferably 73 to 78°C, more preferably 74 to 77°C. If the glass transition temperature of the vinyl chloride-acetate resin is lower than 73° C., it may soften and the ink-receiving layer 2 may not be uniformly formed on the base paper 1 . On the other hand, if the glass transition temperature of the vinyl chloride-acetate-based resin exceeds 78° C., the cushioning properties may deteriorate, resulting in poor transfer. Decreased cushioning properties also cause burrs.

The K value (bearing capacity coefficient) of the vinyl chloride-acetate resin is preferably 55-65, more preferably 56-59. When the K value of the vinyl chloride-acetate resin is less than 55, the ink-receiving layer 2 is likely to be deformed, and may be deformed by external stress. This deformability problem can cause the cut surface to collapse when the thermal transfer image-receiving sheet X is cut. On the other hand, when the K value of the vinyl chloride-acetate resin exceeds 65, the ink-receiving layer 2 becomes difficult to deform, and cracks may occur due to external stress. In addition, it may be a factor of burrs caused by delamination of the base paper 1 and the ink receiving layer 2 .

The content of the vinyl chloride-acetate resin in the ink-receiving layer 2 is preferably 93.0 to 99.8% by mass, more preferably 97.0 to 99.6% by mass. If the content of the vinyl chloride-acetate-based resin is less than 93.0% by mass, the desired ink transfer density may not be obtained. On the other hand, if the content of the vinyl chloride-acetate resin exceeds 99.8% by mass, the ink ribbon may stick to areas other than the designated printing range.

(Ink-receiving layer: release agent)
When the ink-receiving layer 2 contains a release agent, the ink ribbon is prevented from sticking outside the printing area. In addition, the peeling stability is improved, making it suitable for image formation by the subtractive color method.

As the release agent, one conventionally known in the field of sublimation-type thermal transfer image-receiving sheets can be appropriately selected and used. Specifically, for example, silicone oil, polyethylene wax, amide wax, fluorine-based or phosphate ester-based surfactants, and the like can be used.

As silicone oil, for example, various modified silicones can be used. Modified silicone oils are divided into reactive silicone oils and non-reactive silicone oils. Examples of reactive silicone oils include amino-modified, epoxy-modified, carboxyl-modified, carbinol-modified, methacrylic-modified, mercapto-modified, phenol-modified, one-end reactive, and different functional group-modified silicone oils. can be done. Examples of non-reactive silicone oils include polyether-modified, methylstyryl-modified, alkyl-modified, higher fatty acid ester-modified, hydrophilic special modified, higher alkoxy-modified, higher fatty acid-modified, and fluorine-modified silicone oils. can be used. The above modified silicones may be used alone or in combination of two or more. Moreover, silicone oil and another release agent can be used in combination. However, from the viewpoint of releasability from the ink ribbon and prevention of deterioration in the strength of the ink receiving layer 2, it is preferable to use a silicone resin as the release agent.

As the silicone-based resin, for example, one or more selected from amino-modified silicone, epoxy-modified silicone, aralkyl-modified silicone, epoxy-aralkyl-modified silicone, alcohol-modified silicone, vinyl-modified silicone, urethane-modified silicone, and the like. can be used However, it is preferable to use a diamine-modified silicone resin. The diamine-modified silicone resin has a highly adsorptive diamine introduced as an organic group. Therefore, the use of the diamine-modified silicone resin improves the adhesion between the thermal transfer image-receiving sheet X and the ink ribbon, thereby improving the ink transfer density.

When a diamine-modified silicone resin is used as the silicone-based resin, the functional group equivalent weight of diamine, which is an organic group, is preferably 100 to 1800 g/mol, more preferably 150 to 500 g/mol. If the functional group equivalent of the diamine is less than 100 g/mol, the adhesion between the thermal transfer image-receiving sheet X and the ink ribbon may decrease, and the ink transfer density may decrease. The reduction in adhesion of the thermal transfer image-receiving sheet X may also adversely affect the problem of burrs. On the other hand, if the diamine functional group equivalent exceeds 1800 g/mol, the adhesion between the thermal transfer image receiving sheet X and the ink ribbon is excessively increased, and the ink ribbon may stick to areas other than the designated printing range. Moreover, when the functional group equivalent of the diamine exceeds 1800 g/mol, the compatibility with the vinyl chloride-acetate resin may deteriorate.

The content of the silicone resin in the ink-receiving layer 2 is preferably 0.050 to 2.00% by mass, more preferably 0.10 to 1.50% by mass. If the content of the silicone-based resin is less than 0.050% by mass, the ink ribbon may stick to areas other than the designated area. On the other hand, if the content of the silicone-based resin exceeds 2.00% by mass, the ink transfer density may decrease. Moreover, if the content of the silicone-based resin exceeds 2.00% by mass, burrs tend to occur when the thermal transfer image-receiving sheet X is cut.

(Ink receiving layer: adhesion agent)
The ink-receiving layer 2 contains 0.50% by mass or more of the adhesion agent. When the adhesion agent is blended in such a high amount, the cushioning property of the ink-receiving layer 2 is enhanced, and burrs are less likely to occur. This improvement in cushioning property leads to improvement in printability and processability, and in addition, since adhesion between the ink-receiving layer 2 and broadly-defined base paper is improved, delamination between the two is suppressed.

As the adhesion agent, it is preferable to use, for example, a polyolefin-based resin containing one or more polyolefins selected from polyethylene, polypropylene, and the like.

Polyolefin-based resins are mainly composed of α-olefins, and are resins obtained by chlorinating or acid-modifying polyolefins. As the polyolefin resin, a resin having a low modulus of elasticity even at low temperatures is preferable, and a chlorinated polypropylene resin is most preferable in terms of low melting point, low elasticity, film strength, transparency, and the like.

The polyolefin resin preferably has a chlorine content of 20 to 30%. Also, the average molecular weight by GPC method is preferably 30,000 to 50,000.

The content of the adhesion agent in the ink-receiving layer 2 is preferably 0.50 to 2.50% by mass, more preferably 1.00 to 3.00% by mass (including an organic solvent as a medium). It is preferably 0.20 to 0.80% by mass based on the ink-receiving layer coating liquid). When the content of the adhesion agent exceeds 3.50% by mass, the ink-receiving layer 2 becomes strong. Even if the weight is less than 30.0 g/m ² , the ink-receiving layer 2 loses its ability to absorb force, and burrs may occur when the thermal transfer image-receiving sheet X is cut. In addition, the ink-receiving layer 2 may crack.

When using a silicone-based resin as the release agent and a polyolefin-based resin as the adhesion agent, the content of the silicone-based resin in the ink-receiving layer 2 is set to 0.10% by mass or more, and the amount of the silicone-based resin is reduced. The content ratio of the polyolefin resin to the content ratio is preferably 3.0 to 100.0% by mass, more preferably 10.0 to 35.0% by mass. From the viewpoint of peeling stability, the content of the silicone resin in the ink-receiving layer 2 is preferably 0.10% by mass or more. It is preferable to set the content of the polyolefin resin within the above range.

(Ink receiving layer: organic solvent)
The ink receiving layer 2 preferably contains an organic solvent as a solvent. Incorporation of an organic solvent improves the compatibility of various additives such as release agents and adhesion agents, and provides a highly smooth coated surface.

Examples of organic solvents that can be used include toluene, methyl ethyl ketone, acetone, ethyl acetate, tetrahydrofuran, dioxane, cyclohexanone, n-hexane, xylene, methanol, ethanol, n-propanol, and isopropanol.

(Ink receiving layer: other components)
The ink-receiving layer 2 may contain additives, if necessary. Additives include, for example, ultraviolet absorbers, light stabilizers, antioxidants, corrosion inhibitors, tackifiers, plasticizers, softeners, fillers, colorants, pigments, flame retardants, fillers, It is possible to use one or a combination of two or more of hot-melt substances, waxes, and the like.

(Ink-receiving layer: formation method)
As a method for forming the ink-receiving layer 2, for example, a method of directly applying (coating) a paint (ink-receiving layer coating liquid) to a base paper in a broad sense, or a method of once applying a paint to a release film and then applying the paint A method of transferring the formed coating layer to the base paper 1 or the like can be employed.

Coating equipment such as comma coater, lip coater, curtain coater, reverse roll coater, knife coater, bar coater, slot die coater, air knife coater, reverse gravure coater, and vario gravure coater is used for coating of paint. can do.

The amount of coating applied is preferably 10.0 to 50.0 g/m ² , more preferably 12.0 to 28.0 gm ² . If the coating amount of the paint is less than 10.0 g/m ² , the film thickness of the ink-receiving layer 2 may decrease, and the desired ink transfer density may not be obtained. On the other hand, if the amount of paint applied exceeds 30.0 g/m ² , the load in the drying process increases, which may reduce production efficiency. Even if a coating liquid containing 15.0% by mass or less of an adhesion agent is used as the coating liquid for the ink-receiving layer, the absorbability of the force may become insufficient, and burrs may occur.

A drying device such as an oven, a hot air blower, a heating roll, a far-infrared heater, or a hot air circulation drying oven can be used for drying the applied paint.

A cooling process and an aging process can be provided after the paint drying process. Moreover, a bonding process can be provided after that, and a release sheet or the like can be bonded.

(Ink receiving layer: thickness)
The thickness of the ink receiving layer 2 is preferably 1-80 μm, more preferably 10-30 μm. If the thickness of the ink receiving layer 2 is less than 1 μm, the desired ink transfer density may not be obtained. On the other hand, if the thickness of the ink-receiving layer 2 exceeds 80 μm, the load in the drying process increases, possibly deteriorating the curl resistance. Further, even if a coating liquid containing an adhesion agent of 15.0% by mass or less is used as the ink-receiving layer coating liquid, the cushioning properties may be insufficient and burrs may occur.

(Undercoat layer)
Between the base paper 1 (base paper in a narrow sense) and the ink-receiving layer 2, as shown in FIG. It is preferable to provide an undercoat layer 3 for

The undercoat layer 3 includes, for example, SB latex, water-soluble polymer, hollow particles, sizing agent, water-resistant agent, coloring dye, coloring pigment, antifoaming agent, fluorescent whitening agent, fatty acid soap, polyethylene emulsion, surfactant, Contains amide compounds, phosphorus compounds, fluoride compounds, aqueous metal salt solutions, carboxylic acid derivatives, plastic pigments (hollow type, solid type), and the like.

The undercoat layer 3 is preferably formed by a cast coating method. When the undercoat layer 3 is formed by a cast coating method, the flatness of the base paper 1 can be improved as in the case of calendering, but the increase in density of the base paper 1 as in the case of calendering must be suppressed. can be done.

In the cast coating method, the paint for the undercoat layer 3 is applied to the base paper 1, the wet undercoat layer 3 is pressed against the chrome-plated drum, dried, and then peeled off from the chrome-plated drum. It is a coating method that copies the chrome-plated mirror surface.

As the cast coating method, for example, a wet casting method, a precast method, a gelling casting method, a rewet casting method, a dry casting method, or the like can be employed. However, as the cast coating method, it is preferable to employ a rewet casting method, which makes it difficult for the undercoat layer 3 to break even at high temperatures.

More preferably, the undercoat layer 3 is provided in a plurality of layers. In this case, it is preferable that at least the outermost undercoat layer 3 in contact with the ink-receiving layer 2 is formed by a cast coating method. Further, the outermost undercoat layer 3 preferably contains hollow particles. According to this configuration, it is possible to achieve both the contradictory effects of heat insulation (the higher the flatness, the higher the heat insulation effect) and the cushioning property (the lower the flatness, the higher the cushioning property).

The coating amount (one side) of the paint forming the undercoat layer 3 is preferably 2.0 to 25.0 g/m ² , more preferably 4.0 to 20.0 g/m ² . If the coating amount of the paint is less than 2.0 g/m ² , the irregularities (surface properties) of the base paper 1 deteriorate when forming the ink-receiving layer 2 , and the ink-receiving layer 2 is formed along the irregularities of the base paper 1 . There is a possibility that the surface properties of the film may also be deteriorated. On the other hand, if the coating amount of the paint exceeds 25.0 g/m ² , the ratio of the pulp component in the base paper 1 becomes relatively small, and the curl resistance may deteriorate.

Next, examples of the present invention will be described. In addition, the Example described below is an example of this invention. In addition, unless otherwise specified, the content (compounding amount) of each drug described below means the amount in terms of solid content.

An ink-receiving layer is formed by applying an ink-receiving layer coating solution containing vinyl chloride-vinyl acetate copolymer resin (vinyl chloride-acetate resin), silicone-based resin, polyolefin-based resin, and an organic solvent to both or one side of the base paper. was formed to prepare a sublimation-type thermal transfer image-receiving sheet. Details are as follows.

(Base paper A: cast coated paper)
Hardwood kraft pulp (LBKP) and softwood kraft pulp (NBKP) were used as raw material pulp. The mixing ratio of LBKP and NBKP was 80% by mass:20% by mass. The pulp slurry was internally added with heavy calcium carbonate, a coagulant, a retention agent, and a paper strength agent. A raw material pulp slurry was made into paper by an on-top fourdrinier paper machine and dried by a multi-tube dryer to obtain a base paper (base paper in a narrow sense).

Both surfaces of the obtained base paper were coated with a coating material using a rod metalling coater to form a first undercoat layer. The coating amount was 10.0 g/m ² on both sides. As the paint, a mixture of 100.0 parts by mass of heavy calcium carbonate as a white pigment, 10.0 parts by mass of latex, and 10.0 parts by mass of starch was used. Next, the second undercoat layer was formed by applying the paint to both sides of the base paper from above the first undercoat layer using a blade coater. The coating amount was 18.0 g/m ² on both sides. As the paint, a mixture of 30.0 parts by mass of heavy calcium carbonate as a white pigment, 70.0 parts by mass of kaolin, 15.0 parts by mass of latex, and 2.0 parts by mass of starch was used. After forming the second undercoat layer, pressure treatment was performed using a super calender. Further, the second undercoat layer was coated on one side of the base paper with an air knife coater to form a third undercoat layer (outermost layer). The coating amount was 6.0 g/m ² per side. As the paint, heavy calcium carbonate 40.0 parts by weight, kaolin 60.0 parts by weight, hollow particles 8.0 parts by weight, casein 6.0 parts by weight, latex 25.0 parts by weight, stripping agent 2.0 parts by weight A mixture of parts was used. After the formation of the outermost layer, the casting was finished by a rewet method. Table 1 shows the physical properties of the base paper (base paper A).

(Base paper B: single gloss coated paper)
Hardwood kraft pulp (LBKP) and softwood kraft pulp (NBKP) were used as raw material pulp. The mixing ratio of LBKP and NBKP was 80% by mass:20% by mass. Talc, a coagulant, a retention agent, and a paper strength agent were internally added to the raw pulp slurry. A raw material pulp slurry was made into paper by a fourdrinier paper machine and dried by a Yankee dryer to obtain a base paper.

A paint was applied to one side (glossy side) of the obtained base paper (base paper in a narrow sense) with a blade coater to form an undercoat layer. The coating amount was 15.0 g/m ² on one side. As the paint, a white pigment containing 50.0 parts by mass of heavy calcium carbonate, 50.0 parts by mass of kaolin, and 10.0 parts by mass of latex was used. After forming the undercoat layer, pressure treatment was performed using a super calender. Table 1 shows the physical properties of the base paper (base paper B).

(Base paper C: A2 coated paper)
Hardwood kraft pulp (LBKP) was used as raw material pulp (100% by mass). Heavy calcium carbonate, a coagulant, a retention agent, and a paper strength agent were added to the raw material pulp slurry. A raw material pulp slurry was made into paper by an on-top Fourdrinier paper machine and dried by a multi-tube dryer to obtain a base paper.

Both sides of the obtained base paper (base paper in a narrow sense) were coated with a coating material using a rod metering coater to form a first undercoat layer. The coating amount was 14.0 g/m ² on both sides. As the paint, a mixture of 100.0 parts by mass of heavy calcium carbonate as a white pigment, 10.0 parts by mass of latex, and 10.0 parts by mass of starch was used. Next, the second undercoat layer (outermost layer) was formed by applying the paint from above the first undercoat layer to both sides of the base paper with a blade coater. The coating amount was 24.0 g/m ² on both sides. As the paint, a mixture of 65.0 parts by mass of heavy calcium carbonate as a white pigment, 35.0 parts by mass of kaolin, 7.0 parts by mass of latex and 1.0 part by mass of starch was used. After forming the outermost layer, pressure treatment was performed using a super calender. Table 1 shows the physical properties of the obtained base paper (base paper C).

(Vinyl chloride resin)
Solbin CH (manufactured by Nissin Chemical Industry Co., Ltd., vinyl chloride: vinyl acetate = 86:14 (mass basis), degree of polymerization: 650, number average molecular weight: 50000, glass transition temperature: 73 ° C., K value: 57) was used. Table 2 shows the content ratio of the vinyl chloride-acetate resin (base agent) in the ink-receiving layer coating solution.

(silicone resin)
The following agents B-1 to B-4 were used as silicone resins. The content ratio of the silicone resin (release agent) was as shown in Table 2.
Agent B-1: KF-393 (manufactured by Shin-Etsu Chemical Co., Ltd., diamine-modified silicone, functional group equivalent: 350 g/mol)
Agent B-2: KF-8004 (manufactured by Shin-Etsu Chemical Co., Ltd., diamine-modified silicone, functional group equivalent: 1500 g/mol)
Agent B-3: KF-869 (manufactured by Shin-Etsu Chemical Co., Ltd., diamine-modified silicone, functional group equivalent: 3800 g/mol)
Agent B-4: KF-860 (manufactured by Shin-Etsu Chemical Co., Ltd., diamine-modified silicone, functional group equivalent: 7600 g/mol)

(polyolefin resin)
Chemical agent C-1: HARDLEN CY-2129 (manufactured by Toyobo Co., Ltd., chlorine content: 29%) was used as the polyolefin resin. The content ratio of the polyolefin resin (adherence agent) was as shown in Table 2.

(Organic solvent)
Toluene (commercially available) was used as an organic solvent. The content ratio of the organic solvent was as shown in Table 2.

(quality evaluation)
A test for evaluating the quality of each sublimation-type thermal transfer image-receiving sheet X was conducted. Table 2 shows the results. The methods for measuring the physical properties of the base paper and the test methods for quality evaluation were as follows. Basis weight, density, and arithmetic mean roughness were as described above.

(Clark stiffness)
Measured in accordance with JIS P 8143 (2009) "Paper - Stiffness Test Method - Clark Stiffness Tester Method".

(Beck smoothness)
Measured in accordance with JIS P 8119 (1998) "Paper and paperboard-Smoothness test method by Bekk smoothness tester".

(ink transfer density)
An ink ribbon was used for printing on the sublimation-type thermal transfer image-receiving sheet, thermal transfer was performed, and an image for evaluation was printed. Next, the ink transfer density of the printed portion of the sublimation type thermal transfer image-receiving sheet X was measured with a Macbeth reflection densitometer RD-918 (manufactured by Colmorgen Corporation, USA) (the higher the ink transfer density, the clearer and better the image is. indicating that the pattern has been transferred).

(Ink ribbon transfer suitability)
The adhesion between the sublimation thermal transfer image-receiving sheet and the link ribbon was evaluated when 10 ink ribbons with different manufacturing numbers were attached to the sublimation thermal transfer image-receiving sheet by a transfer device. The evaluation criteria were as follows.
⊚: No link ribbon was adhered outside the specified printing range, and the sheet was suitable as a sublimation-type thermal transfer image-receiving sheet.
◯: 1 to 2 link ribbons adhered outside the specified printing range, which was within the range of practical use as a sublimation type thermal transfer image-receiving sheet.
Δ: 3 link ribbons adhered outside the specified printing range, and it was somewhat difficult to put it to practical use as a sublimation type thermal transfer image-receiving sheet.
x: Four or more link ribbons adhered outside the specified printing range, and the sheet could not be used as a sublimation thermal transfer image-receiving sheet.

(Seropic strength)
Seropic evaluation was performed using a transparent adhesive tape (CT405A-18 manufactured by Nichiban). A tape was attached to the surface of the sublimation type thermal transfer image-receiving sheet, and the sheet was pressed back and forth 20 times with a rubber roller. The evaluation criteria were as follows.
◯: The ink-receiving layer and the base paper are in close contact with each other, and no peeling is observed.
Δ: The ink-receiving layer and the base paper are slightly separated, but there is no problem in use.
x: The ink-receiving layer and the base paper are separated (burrs are generated) and cannot be used.

(Curl aptitude)
Each sublimation type thermal transfer sheet was cut into a 10 cm square sample, and this sample was stored in a drier at 190 to 215° C. for 1 minute. Place the sample after storage on the surface plate so that the ink-receiving layer is on the top surface, measure the lift height of each of the four corners from the surface plate while the sample is stationary, and calculate the average value of the measured values. asked. The evaluation criteria were as follows.
◯: Average curl value is 30 mm or less, suitable as a sublimation thermal transfer image-receiving sheet.
Δ: The average curl value is 50 mm or less, which is within a range that poses no problems when used as a sublimation thermal transfer image-receiving sheet.
x: The average curl value exceeds 50 mm and cannot be used as a sublimation thermal transfer image-receiving sheet.

INDUSTRIAL APPLICABILITY The present invention can be used as a sublimation-type thermal transfer image-receiving sheet and a method for producing the same.

DESCRIPTION OF SYMBOLS 1... Base paper, 2... Ink-receiving layer, 3... Undercoat layer, X... Thermal transfer image-receiving sheet

Claims (8)

having a base paper and an ink-receiving layer formed on one or both sides of the base paper,
The base paper is a cast-coated paper in which the undercoat layer is a coat layer ,
This cast-coated paper has an arithmetic mean roughness of 0.10 to 0.60 μm measured according to JIS B 0601 (2013) and a density of 0.80 measured according to JIS P 8118 (2014). ~1.20 g/ ^cm3 ,
The undercoat layer has a plurality of layers, and at least the outermost layer in contact with the ink-receiving layer contains hollow particles formed by a rewet casting method,
The ink-receiving layer contains a base agent, a release agent, and a polyolefin-based resin, and the content of the polyolefin-based resin is 0.50% by mass or more.
A sublimation-type thermal transfer image-receiving sheet characterized by: The release agent is a silicone resin,
The content of the silicone-based resin in the ink-receiving layer is 0.10% by mass or more, and the content of the polyolefin-based resin is 300 to 2910 parts by mass with respect to 100 parts by mass of the silicone-based resin.
The sublimation-type thermal transfer image-receiving sheet according to claim 1. The ink-receiving layer has a thickness of 1 to 80 μm and a content of the polyolefin resin of 15.0% by mass or less.
The sublimation-type thermal transfer image-receiving sheet according to claim 1 or 2. The base agent is a vinyl chloride-vinyl acetate copolymer resin, and vinyl chloride: vinyl acetate = 85-95: 5-15 (by mass),
The sublimation-type thermal transfer image-receiving sheet according to any one of claims 1 to 3. The polyolefin resin has a chlorine content of 20 to 30% by mass.
The sublimation-type thermal transfer image-receiving sheet according to claim 4. The silicone-based resin is a diamine-modified silicone resin, and the functional group equivalent of diamine, which is an organic group, is 100 to 1800 g / mol.
The sublimation-type thermal transfer image-receiving sheet according to claim 2. The cast coated paper has a paper thickness of 66 to 188 μm measured according to JIS P 8118 (1998).
The sublimation-type thermal transfer image-receiving sheet according to any one of claims 1 to 6. The arithmetic mean roughness measured in accordance with JIS B 0601 (2013) is 0.00, measured according to JIS B 0601 (2013) after forming a multi-layered undercoat layer in which at least the outermost layer in contact with the ink-receiving layer contains hollow particles . Cast-coated paper having a thickness of 10 to 0.60 μm and a density of 0.80 to 1.20 g/cm ³ measured according to JIS P 8118 (2014),
An ink-receiving layer coating liquid is applied to the outermost layer of the cast-coated paper,
As the ink-receiving layer coating liquid, a coating liquid containing a base agent, a release agent, and a polyolefin-based resin and having a content of the polyolefin-based resin of 0.20% by mass or more is used.
A method for producing a sublimation-type thermal transfer image-receiving sheet, characterized by:

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