JPH06227157A - Support for heat transfer type thermal transfer recording image receiving material - Google Patents

Abstract

(57) [Summary] [Purpose] It is an object of the present invention to provide an excellent support for a heat transfer type thermal transfer recording image receiving material which does not cause transfer omission and uneven density in a printed portion and can obtain high density. [Structure] Paper with natural pulp as the main component,
In the support for heat transfer type thermal transfer recording image receiving material in which one of the image receiving side paper substrate surface is coated with polyolefin resin, the substrate paper is a specific value of the film thickness unevenness index value measured using an optical displacement sensor. A support for a heat transfer type thermal transfer recording image receiving material, characterized in that:

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermal transfer type thermal transfer used for recording by transferring a thermal transferable dye such as a sublimable dye or a diffusible dye of a thermal transfer material in thermal transfer recording such as a thermal printer. The present invention relates to a support for a recording image receiving material, and more specifically, to a heat transfer type thermal transfer recording image receiving material support capable of obtaining a high density without transfer defects and density unevenness in a printing portion.

[0002]

2. Description of the Related Art As a conventional heat transfer type thermal transfer recording image receiving material, there is known a synthetic paper provided with a coating layer such as a saturated polyester resin on the surface thereof. This type of thermal transfer recording image receiving material is polyethylene terephthalate. Is used in combination with a thermal transfer material consisting of a heat transferable dye and a binder, etc., and both of these materials are superposed so that the thermal transfer layer and the image receiving layer are in contact with each other. Attempts have been made to form a natural color photographic image by transferring the heat transferable dye in the thermal transfer layer to the image receiving layer by heating with a heat sensitive means such as a thermal head which generates heat under the control of a signal. The heat transferable dye here is
It is a dye that can be transferred from a thermal transfer material to a thermal transfer image receiving material by sublimation or diffusion in a medium.

However, in the above heat transfer type thermal transfer recording image receiving material, when synthetic paper composed of a resin having low heat resistance such as polypropylene resin is used as a support, the synthetic paper is heated by the heat during image formation. Distortion remains, and the image receiving material after image formation curls. Further, even when a synthetic paper composed of a resin having a high heat resistance is used as the support, sufficient cushioning and heat insulating properties of the support are inferior, so that sufficient printing density cannot be obtained.

Various efforts have been made in the past to remedy these drawbacks. In particular, a large number of supports for heat transfer type thermal transfer recording image receiving materials using paper as a substrate have been proposed because they are required to have a feeling of touch and a texture close to that of a photograph.

For example, Japanese Patent Application Laid-Open No. 62-198497 proposes a support for a heat transfer type thermal transfer recording image receiving material in which a synthetic paper is attached to at least one surface of a paper substrate. By this proposal, the curl of the image-receiving material after image formation was improved, but the smoothness of the support was inferior to that of the support made of synthetic paper alone, and there was a problem such as image transfer omission. JP-A-60-236794 discloses a support for a heat transfer type thermal transfer recording image receiving material in which a thermoplastic polymer material layer is provided on a base paper, but the reproducibility of image quality is not sufficient. It was

US Pat. No. 4,774,224 has a surface roughness Ra.
It has been proposed to use a resin-coated paper having a small size as a support for a heat transfer type thermal transfer recording image receiving material. Although the curl of the image receiving material after image formation was improved by this proposal, the value as a product is remarkably reduced due to the occurrence of transfer omission and uneven density in the printing portion, or insufficient printing density. There were problems such as. Further, the polyethylene resin-coated paper exemplified in JP-A 1-267090 has not only the problem that the printing part causes transfer omission and uneven density, but also the problem that the printing density is low.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to obtain a high print density without the above-mentioned problems such as curl after printing, transfer omission and uneven density in a printing portion. An object is to provide an excellent support for a heat transfer type thermal transfer recording image receiving material.

[0008]

[Means for Solving the Problems] The inventors of the present invention have conducted extensive studies to solve the above problems, and as a result, paper containing natural pulp as a main component was used as a substrate, and one of the image receiving side paper substrates (hereinafter In the support for heat transfer type thermal transfer recording image receiving material whose surface is coated with a polyolefin resin, the thickness unevenness index Rp (thickness unevenness index in the papermaking direction) defined in the following as a base paper is defined. It has been found that the object of the present invention can be achieved by using a film having a film thickness unevenness index of 1.65 mV or less. The film thickness unevenness index Rp referred to in the present specification is an optical displacement sensor that irradiates red LED light from above the plane and captures reflected light with a light receiver array to measure the position of the plane. At a distance of 13 mm where the level meter needle is located in the center, the lower surface of the sample directly below the beam is supported by a ball point needle, and the sample is fixed to the XY stage while preventing vertical displacement, and the XY stage is set to the X-axis ( The thickness variation in the papermaking direction of the sample is measured by scanning at a constant speed of 2 mm / sec in the (main scanning axis) direction, and the obtained measurement signal value is used with the Hanning window for the time window using the FFT analyzer. Fast Fourier transform to obtain a power spectrum (unit: mV ² ) by adding and averaging 128 integrations.
A value (unit: m) obtained by summing the power values in the frequency range of Hz to 2 Hz and multiplying by 2/3
V).

Specifically, it is obtained as follows. Red LED
K is an optical displacement sensor that measures the position of the plane by irradiating the light beam from above the plane and capturing the reflected light with the light receiver array.
PA1800 and PA182 manufactured by EYENCE Co., Ltd.
0 is used, and the sensitivity changeover switch of PA1800 is WHIT
E, with the response speed set to 2 mS, as shown in Fig. 1, there is a distance of about 13 mm between the sensor and the sample and the center of the level meter needle, and the bottom surface of the sample just below the beam is supported by a ball point with a diameter of 4 mm. Fix the sample on the XY stage with the shape as shown in FIG.
The thickness variation in the papermaking direction of the sample is measured by scanning the XY stage in the X-axis (main scanning axis) direction at a constant speed of 2 mm / sec.
The obtained measurement values were processed using an Ono Sokki Co., Ltd. FFT analyzer CF-300 model (input signal AC ± 10 mV, sampling 512 points) with a Hanning window for the time window and a frequency range of 5 Hz. Fast Fourier Transform (FFT) to find the power spectrum (unit: mV) on the linear scale by adding and averaging 128 times, and square each power value on the linear scale in the frequency range of 0.175Hz to 2Hz. Can be obtained by multiplying the value obtained by summing and multiplying it by 2/3 and raising it to the power of 1/2. The other processing conditions are the initial setting conditions of the CF-300 type machine.

Further, it has been found that the object of the present invention can be effectively achieved by using a base paper having a film thickness unevenness index Rp of 1.55 mV or less as referred to in the present specification. Further, an object of the present invention is that the polyolefin resin is a polyethylene resin and the coating thickness of the resin is 4 μm to 10 μm.
The present invention has been found out by the fact that it can be more remarkably achieved by the constitution of μm.

The base paper containing natural pulp as a main component used in the practice of the present invention has a thickness unevenness index Rp defined in this specification of 1.65 mV or less, but is 1.55.
It is preferably mV or less, more preferably 1.45 mV or less. For the base paper having a thickness unevenness index Rp of 1.65 mV or less, specifically, the following methods are used, preferably 2 or more, more preferably 3 or more, and most preferably 4 or less. It has been clarified by the study of the present inventors that the above-mentioned combination can be used.

(1) As the natural pulp to be used, a large amount of hardwood pulp, which has short fibers and is easily smooth, is used. Specifically, for example, the hardwood pulp described or exemplified in JP-A-60-69649 contains 60% by weight or more, preferably 75% by weight.
Used above.

(2) As the beating condition for pulp, beating is performed by a beating machine so that the long fiber content is reduced as much as possible.
Specifically, for beating of pulp, for example, the length-weighted average fiber length measured in accordance with JAPAN TAPPI Paper Pulp Test Method No. 52-89 “Test method for fiber length of paper and pulp” is 0.4
mm to 0.75 mm, preferably 0.45 mm to 0.7 mm, more preferably 0.45 mm to 0.65 mm, fiber length 1 mm or less, cumulative weight 70% or more, freeness 200 to 330 CSF
Try to be.

(3) A base paper is made into paper by a Fourdrinier paper machine so as to obtain a uniform formation by adopting an appropriate paper making method for a stock slurry containing an internal additive chemical. Specifically, for example, the stock slurry is provided with an appropriate turbulence. A Fourdrinier paper machine having an appropriate upper dehydration mechanism as described or exemplified in JP-A-61-284762 is used. As a press for the wet part, a multi-stage wet press, preferably a wet press with three or more stages is performed, and a smoothing roll is provided at the final stage of the press part.

(4) A tenacity press is used during the drying of the wet paper. Specifically, the wet paper web is subjected to a multi-stage pressure press as described or exemplified in JP-A-3-29945.

(5) After making the base paper, calendering is performed using a machine calender, a super calender, a thermal calender, or the like. Specifically, it is preferable to perform the thermal calendar treatment described or exemplified in JP-A-60-126397.

As the pulp constituting the base paper used in the practice of the present invention, it is advantageous to use the above-mentioned appropriately selected natural pulp. Natural pulp was subjected to usual bleaching treatment such as chlorine, hypochlorite, chlorine dioxide bleaching, alkali extraction or alkali treatment and, if necessary, oxidative bleaching treatment with hydrogen peroxide, oxygen, etc., and a combination thereof. Wood pulp such as softwood pulp, hardwood pulp, and hardwood mixed hardwood pulp is used, and various types such as kraft pulp, sulfite pulp, and soda pulp can be used.

The base paper used for carrying out the present invention may contain various additives when preparing a stock slurry. As a sizing agent, a fatty acid metal salt and / or a fatty acid, an alkyl ketene dimer emulsion or an epoxidized higher fatty acid amide, an alkenyl or alkyl succinic anhydride emulsion described in JP-B-62-7534, an alkenyl or alkylsuccinic anhydride emulsion, a rosin derivative, etc. are dried. As a paper strength agent, anionic, cationic or amphoteric polyacrylamide, polyvinyl alcohol, cationized starch, vegetable galactomannan, etc., as a wet paper strength agent, polyamine polyamide epichlorohydrin resin, etc., as a filler, clay,
Kaolin, calcium carbonate, titanium oxide, etc., as a fixing agent, water-soluble aluminum salts such as aluminum chloride and vanadium sulfate, etc., as a pH adjusting agent, caustic soda, sodium carbonate, sulfuric acid, etc., as well as JP-A-63-204251. Japanese Patent Laid-Open No. 1-26
It is advantageous to contain a coloring pigment, a coloring dye, a fluorescent whitening agent, etc. described or exemplified in 6537 in an appropriate combination.

Further, in or on the base paper used in the practice of the present invention, a composition comprising various water-soluble polymers, antistatic agents, and additives is subjected to size press or tab size press or blade coating, air knife. It can be contained or applied by coating such as coating. As the water-soluble polymer, starch-based polymers, polyvinyl alcohol-based polymers, gelatin-based polymers, polyacrylamide-based polymers, cellulose-based polymers and the like described or exemplified in JP-A 1-266537, and antistatic agents such as sodium chloride and potassium chloride Emulsions, latexes, petroleum resin emulsions, etc., such as alkali metal salts of, alkaline earth metal salts such as calcium chloride and barium chloride, colloidal metal oxides such as colloidal silica, organic antistatic agents such as polystyrene sulfonate, etc. , Emulsions or latices of copolymers containing at least ethylene and acrylic acid (or methacrylic acid), which are described or exemplified in JP-A-55-4027 and JP-A-1-180538, styrene-butadiene series, styrene. -Acrylic, vinyl acetate-acrylic , Ethylene-vinyl acetate-based, butadiene-methyl methacrylate-based copolymers and emulsions or latexes of carboxy-modified copolymers thereof, as pigments, clay, kaolin, calcium carbonate, talc, barium sulfate, titanium oxide, pH As regulators, hydrochloric acid, phosphoric acid, citric acid,
Advantageously, caustic soda and the like, as well as other additives such as the above-mentioned coloring pigments, coloring dyes and optical brighteners, are appropriately combined and contained.

The thickness of the base paper used for carrying out the present invention is not particularly limited, but the basis weight is 20 g / m ^{2 to} 20.
It is preferably 0 g / m ² .

The surface of the base material of the support for heat transfer type thermal transfer recording image receiving material in the present invention on which the image receiving layer is provided (hereinafter abbreviated as the front side) is coated with a polyolefin resin. As those polyolefin resins, homopolymers such as polyethylene, polypropylene, polybutene and polypentene,
2 of α-olefin such as ethylene-butylene copolymer
A copolymer of one or more and a mixture thereof,
Particularly, a polyethylene resin is particularly preferable from the viewpoints of the effect of the present invention, the melt extrusion coating property, and the adhesive property with the base paper. Examples of the polyethylene-based resin include low-density polyethylene, medium-density polyethylene, high-density polyethylene, linear low-density polyethylene, copolymers of ethylene and α-olefins such as propylene and butylene, carboxy-modified polyethylene, and the like. It is a mixture of various densities and melt flow rates (hereinafter referred to as JIS K 67
A melt flow rate defined by 60 is simply abbreviated as MFR), a molecular weight and a molecular weight distribution can be used, but usually, the density is in the range of 0.90 to 0.97 g / cm ³ , the MFR is 0.
1 g / 10 minutes to 50 g / 10 minutes, preferably MFR 0.3 g / 10
Those in the range of minutes to 40 g / 10 minutes can be advantageously used alone or as a mixture. Particularly, it is preferable to use at least 10% by weight or more of a high density polyethylene resin mixed in a polyethylene resin. When the amount of the high-density polyethylene resin added is less than 10% by weight, the resin layer is softened by the heat generated by the thermal head during printing by the printer, and the feeding failure of the image receiving sheet tends to occur. When the resin has a multi-layered structure, the resin of the outermost layer is, for example, MFR.
It is also possible to use a resin having a different property or constitution, such as a resin of 5 g / 10 minutes to 20 g / 10 minutes, or a resin of the lower layer having a MFR of 2 g / 10 minutes to 10 g / 10 minutes.

The surface of the support for heat transfer type thermal transfer recording image-receiving material in the present invention opposite to the side on which the image-receiving layer is provided (hereinafter abbreviated as back side) has a curl-preventing property of the image-receiving sheet, suitability for feeding, antistatic property and the like. It is preferable to coat with a resin capable of forming a film in order to impart As the resin capable of forming a film, a polyolefin resin, a polycarbonate resin, a polyester resin, a thermoplastic resin such as a polyamide resin is preferable, and among them, the above-mentioned polyolefin resin is more preferable from the viewpoint of melt extrusion coating property,
Polyethylene resins are particularly preferred. Also, Japanese Examined Sho 60-1
It may be coated with an electron beam curing resin described or exemplified in No. 7104.

As a method of coating the base paper surface of the support for heat transfer type thermal transfer recording image receiving material with a polyolefin resin in the present invention, a resin composition is melt-extruded on a running base paper, and a film is produced from the slit die of the resin composition. It is preferable to perform coating by a so-called melt extrusion coating method, in which the coating is performed by casting. At this time, the temperature of the molten film is preferably 270 ° C to 340 ° C. The slit die is preferably a flat die such as a T-type die, an L-type die or a fishtail type die, and the slit opening diameter is preferably 0.1 mm to 2 mm. Further, it is preferable that the base paper is subjected to an activation treatment such as a corona discharge treatment or a flame treatment before the base paper is coated with the resin composition. Further, as described in JP-B No. 61-42254, it is preferable to coat the resin layer on the running base paper after blowing the ozone-containing gas onto the molten resin composition on the side in contact with the base paper. The front and back resin layers are preferably extrusion-coated sequentially, preferably continuously, so that the base paper is coated by a so-called tandem extrusion coating method. Further, the surface resin layer surface of the support for the image receiving material on which the image receiving layer is coated is a glossy surface, which can be processed into a finely rough surface described in JP-B-62-19732, a matte surface or a silk surface, The back resin layer on the opposite side is usually preferably processed into a matte surface.

The coating thickness of the polyolefin resin on the front side of the support for heat transfer type thermal transfer recording image-receiving material in the present invention is usefully in the range of 4 μm to 45 μm, and 6 μm.
The range of ˜35 μm is preferable. A polyethylene resin is used as the polyolefin resin, and its coating thickness is 4 μm to 10 μm, and particularly preferably 6 μm to 10 μm.
When it is m, the effect of the present invention is more remarkably achieved. If the coating thickness of the resin is too thin, the uniform coating property of the resin and the adhesiveness between the resin and the base paper will deteriorate, and there will be a large tendency for transfer omission and uneven density in the printed area to occur. If the thickness is too thick, especially when the resin is a polyethylene resin, the density of the printed portion tends to decrease. Further, the back surface of the base paper of the support for the image receiving material is preferably coated with a resin capable of forming a film, but the resin is preferably the same resin as the resin on the front side, and the coating thickness is the resin on the front side. It is preferable to appropriately set the layer and the range in which the curl balance is taken, and it is generally 4 μm to 4 μm.
A range of 5 μm is useful.

Various additives can be contained in the resin layer of the support for heat transfer type thermal transfer recording image receiving material in the present invention. Japanese Patent Publication No. 60-3430, Japanese Patent Publication No. 63-11655
Japanese Patent Publication No. 1-38291, Japanese Patent Publication No. 1-38292, Japanese Patent Laid-Open No. 1-10
Titanium oxide, zinc oxide described or exemplified in No. 5245,
White pigments such as talc and calcium carbonate, fatty acid amides such as stearic acid amide and arachidic acid amide, zinc stearate, calcium stearate, aluminum stearate, magnesium stearate, zinc palmitate, zinc myristate, calcium palmitate, and other fatty acids. Metal salts, various antioxidants such as hindered phenol, hindered amine, phosphorus-based, and sulfur-based antioxidants described in JP-A-1-105245, cobalt blue, ultramarine blue, cerian blue, phthalocyanine blue, and other blue pigments and dyes , Cobalt violet, fast violet,
Various additives such as magenta pigments and dyes such as manganese violet, fluorescent brighteners and ultraviolet absorbers described or exemplified in JP-A-2-254440, and the like can be contained in an appropriate combination. The additives are preferably contained as a resin masterbatch or compound.

The surface of the backing resin layer of the support for heat transfer type thermal transfer recording image-receiving material in the present invention is subjected to activation treatment such as corona discharge treatment and flame treatment, and then various back coats for preventing electrostatic charge and the like. Layers can be applied. Also,
For the back coat layer, Japanese Patent Publication Nos. 52-18020 and 57-905
No. 9, JP-B 57-53940, JP-B 58-56859, JP 59
-214849, JP-A-58-184144 or the like, or an inorganic antistatic agent, an organic antistatic agent, a hydrophilic binder, a latex, a curing agent, a pigment, a surfactant or the like may be contained in appropriate combination. it can.

Examples of the synthetic resin used in the heat transfer type thermal transfer recording image receiving layer according to the present invention include polyester resin, polyacrylic ester resin, polycarbonate resin, polyvinyl acetate resin, polyvinyl butyral resin, styrene acrylate resin and vinyl toluene acrylate. Resin having ester bond such as resin, resin having urethane bond such as polyurethane resin, resin having amide bond such as polyamide resin, resin having urea bond such as urea resin,
Other examples include polycaprolactam resin, styrene resin, polyvinyl chloride resin, vinyl chloride-vinyl acetate copolymer resin, polyacrylonitrile resin and the like. In addition to these resins, mixtures or copolymers thereof can be used.

In the heat transfer type thermal transfer recording image receiving layer according to the present invention, a releasing agent, a pigment or the like may be added in addition to the above synthetic resin. Examples of the releasing agent include solid waxes such as polyethylene wax, amide wax and Teflon powder, fluorine-based and phosphoric acid ester-based surfactants, silicone oils and the like. Among these release agents, silicone oil is most preferable. An oily substance can be used as the silicone oil, but a curable type is preferable. As the curable silicone oil, reaction curable type, light curable type,
Examples thereof include catalyst-curable type, and reaction-curable type silicone oil is particularly preferable. Examples of the reaction-curable silicone oil include amino-modified silicone oil and epoxy-modified silicone oil. The amount of the reactive silicone oil added is preferably 0.1 to 20 wt% in the image receiving layer. As the pigment, extender pigments such as silica, calcium carbonate, titanium oxide and zinc oxide are preferable. Further, the thickness of the image receiving layer is preferably 0.5 to 20 μm, and 2 to 10
μm is more preferable.

[0029]

The present invention will be described in detail below with reference to examples, but the contents of the present invention are not limited to the examples.

Example 1 A mixed pulp consisting of 50% by weight of hardwood bleached kraft pulp, 35% by weight of hardwood bleached sulfite pulp and 15% by weight of softwood bleached sulfite pulp was beaten to a fiber length shown in Table 1, To 100 parts by weight of pulp, 3 parts by weight of cationized starch, 0.2 part by weight of anionized polyacrylamide, 0.4 part by weight of emulsion of alkyl ketene dimer (as ketene dimer content), 0.4 part by weight of polyamide epichlorohydrin resin. And an appropriate amount of optical brightener, blue dye and red dye were added to prepare a stock slurry. Then, the stock slurry was placed on a Fourdrinier paper machine running at 200 m / min to form a web while giving an appropriate turbulence, and 15 kg / cm -100 in a wet part.
After performing 3 stages of wet press where the line pressure was adjusted in the range of kg / cm, it was treated with smoothing rolls and 2 stages where the line pressure was adjusted in the range of 30 kg / cm to 70 kg / cm in the subsequent drying part. It was dried after being pressed. afterwards,
4 parts by weight of carboxy-modified polyvinyl alcohol, 0.05 part by weight of optical brightener, 0.002 of blue dye in the middle of drying
25 g / m ² size press liquid consisting of 4 parts by weight of sodium chloride, 4 parts by weight of sodium chloride and 92 parts by weight of water, and dried so that the moisture content of the base paper finally obtained is 8% by weight. By machine calendering under the conditions shown in Table 1, a base paper for a heat transfer type thermal transfer recording image receiving material support having a basis weight of 170 g / m ² and having a film thickness unevenness index Rp shown in Table 1 was produced.

Next, after the corona discharge treatment was applied to the base paper surface (back surface) opposite to the side on which the image receiving layer was coated, a low density polyethylene resin (density 0.92 g / cm ³ , MFR = 2 g / 10 min) Three
5 parts by weight and high-density polyethylene resin (density 0.96 g / cm
³ , MFR = 20 g / 10 min) 65 parts by weight of a resin composition was melt-extrusion coated at a resin temperature of 320 ° C. to a thickness of 13 μm at a running speed of the base paper of 150 m / min.

Subsequently, the surface of the base paper was subjected to corona discharge treatment, and then the low density polyethylene resin (density 0.92) was applied to the surface.
0 g / cm ³ , MFR = 8.5 g / 10 min) 47.5% by weight, aluminum oxide hydroxide (vs titanium dioxide to Al ₂ O ₃
50% by weight of anatase titanium dioxide pigment surface-treated with 0.75% by weight) and zinc stearate 2.5
20% titanium dioxide pigment masterbatch by weight
Parts by weight, low-density polyethylene resin (density 0.920 g / cm
^3, MFR = 4.5g / 10 min) 65 parts by weight of a high density polyethylene resin (density ^{0.970g / cm 3, MFR = 7.0g} /
10 minutes) A resin composition consisting of 15 parts by weight is added at a resin temperature of 325
The base paper was melt extrusion coated to a thickness of 13 μm at a running speed of 150 m / min. The melt extrusion coating of the front and back polyethylene resins was performed by a so-called tandem method in which extrusion coating was sequentially performed. At that time, the surface of the resin layer containing the titanium dioxide pigment of the resin-coated paper was processed into a mirror surface, and the surface quality of the resin layer on the back was processed into a matte surface such as paper.

Then, after the corona discharge treatment on the backside resin layer of the resin-coated paper, the dry weight content of gelatin: starch granule matting agent (average particle size 2 μm) = 1: 1, and the epoxy system containing 15% by weight of gelatin. In addition to a hardening agent, a back coat coating solution containing an appropriate amount of a coating aid and an inorganic antistatic agent is applied at a coating amount of 3 g / m ² min as a gelatin component to support a heat transfer type thermal transfer recording image receiving material. Got

Then, after corona treatment was applied to the surface of the resin surface, a heat transferable dye image receiving layer having the following composition was coated using a wire bar and dried to form an image receiving layer having a solid content of 5 g / m ^2. An image receiving sheet for heat transfer type thermal transfer recording was obtained. Composition for forming heat transferable dye image-receiving layer Saturated polyester resin (TP-220: manufactured by Nippon Gosei Co., Ltd.): 10 parts by weight Amino-modified silicone (KF-393: manufactured by Shin-Etsu Chemical Co., Ltd.): 0.5 part by weight Solvent ( Xylene / methyl ethyl ketone = 1/1): 30 parts by weight

Next, a heat transfer type thermal transfer layer forming ink composition having the following composition was prepared and heat-treated on the back side to a thickness of 6
A thermal transfer sheet was obtained by coating a polyethylene terephthalate film having a thickness of 1 μm so that the solid coating amount was 1 g / m ² , and drying. Heat transfer dye (CISOLVENT BLUE 95): 5 parts by weight Polysulfone resin: 10 parts by weight Chlorobenzene: 85 parts by weight

Solid printing was performed by combining the thermal transfer sheet and the thermal transfer recording image-receiving sheet obtained as described above and applying an applied energy with a thermal head. Then, the density of the printed portion was measured with a Macbeth densitometer, and the transfer omission and the uneven density of the printed portion were visually determined. The applied energy of the sample for determining transfer omission and uneven density was adjusted to a range lower than the applied energy of the sample for density measurement. The results obtained are shown in Table 1.

[0037]

[Table 1]

Note that (Note 1) to (Note 4) in Table 1 are as follows.

(Note 1) ◯ represents the sample according to the present invention.

(Note 2) About pulp after beating JAPAN TA
Length-weighted average fiber length (mm) measured in accordance with PPI Paper and Pulp Test Method No 52-89 "Paper and Pulp Fiber Length Test Method"
Represents The measurement is carried out by an FS-100 model manufactured by Kajaani.

(Note 3) Indicates the thickness unevenness index Rp (mV) of the base paper measured by the method specified in the present specification.

(Note 4) The evaluation criteria are as follows. ⊚: No or almost no transfer defects and uneven density. ◯: Transfer dropout and uneven density are slightly observed. Δ: Practical application is possible although some transfer omission and density unevenness are observed. Poor: Transfer defects and uneven density are observed, which is a problem in practical use.

As is clear from Table 1, the film thickness unevenness index Rp
The substrate for a heat transfer type thermal transfer recording image receiving material of the present invention in which the base paper surface is coated with polyethylene resin is used as a substrate, and the support for the thermal transfer type thermal transfer recording image receiving material is free from problems such as transfer omission and uneven density in the printed portion. You can see that it is the body. Further, as the base paper in the present invention, those having a film thickness unevenness index of 1.55 mV or less are preferable, and a film thickness of 1.45 mV or less, from the viewpoints of the effect of improving the transfer omission and density unevenness of the printing portion and the print density. It can be seen that those having the unevenness index are more preferable.

Example 2 Using the base paper used in Sample Nos. 3 and 3 of Example 1, except that the coating thickness of the resin composition for coating the base paper surface on the image receiving side is the coating thickness shown in Table 2. It carried out like Example 1. The obtained results are shown in Table 2.

[0045]

[Table 2]

Note that (Note 5) in Table 2 has the same meaning as (Note 4) in Table 1.

From the results shown in Table 2, the resin composition on the image receiving side (front side) is a polyethylene resin composition, and the coating thickness of the resin composition is 4 μm to 10 μm. It can be seen that there is no problem of transfer omission and density unevenness, and the print density is high, and it is a particularly excellent heat transfer type thermal transfer recording image receiving material support. In addition, when the coating thickness of the resin composition is less than 4 μm, there is a problem in uniform coating property of the resin composition.

Example 3 A polypropylene resin (JISK 67) containing 7 mol% of ethylene component was used as a resin composition for coating the base paper surface on the image receiving side using the base paper used in Sample No. 6 of Example 1.
90 parts by weight of MFR 21 g / 10 minutes specified by 58), 10 parts by weight of the anatase type titanium dioxide pigment used in Example 1 and 2.5 parts by weight of zinc stearate are coated to a thickness of 26 μm. Sample N of Example 1 except that the thickness of the polyethylene resin composition on the back side is 30 μm.
It carried out like o and 6.

As a result, there was no problem of transfer omission and density unevenness in the printing portion, and a high print density of 1.06 was obtained, and the support was an excellent heat transfer type heat transfer recording image receiving material support. I understand.

[0050]

According to the present invention, it is possible to provide an excellent support for a heat transfer type thermal transfer recording image receiving material, which is free from omission of transfer and uneven density in a printing portion and can obtain high printing density.

[Brief description of drawings]

FIG. 1 is a schematic diagram of a measurement procedure of a film thickness unevenness index Rp with an optical displacement sensor.

FIG. 2 is a schematic diagram of a measurement XY stage.

[Explanation of sign]

 1, measurement sample 2, optical displacement sensor head 3, optical displacement sensor controller 4, ball point 5, FFT analyzer 6, data processing personal computer 7, red LED light 8, ball point height adjustable stand 9, XY stage 10, measurement sample fixing part

Claims (5)

[Claims] 1. In a support for a heat transfer type thermal transfer recording material in which a paper mainly composed of natural pulp is used as a substrate, and one of the image receiving side paper substrate surfaces is coated with a polyolefin resin, the substrate paper is as follows: A support for a heat transfer type thermal transfer recording image receiving material, which has a thickness unevenness index Rp in the papermaking direction defined by 1. Thickness unevenness index Rp: An optical displacement sensor that irradiates red LED light from above the flat surface and captures the reflected light with a row of light receivers to measure the position of the flat surface. The sample is fixed to the XY stage in a state where it is positioned at the center and supports the lower surface of the sample just below the beam with a ball point needle and prevents vertical displacement.
The thickness variation in the papermaking direction of the sample is measured by scanning the XY stage in the X-axis (main scanning axis) direction at a constant speed of 2 mm / sec.
Using the FFT analyzer, the obtained measurement signal value
Fast Fourier transform is performed using Hanning window for the time window, and the power spectrum (unit: mV ² ) is calculated by adding and averaging 128 times of integration, and the power values in the frequency range of 0.175 Hz to 2 Hz are summed to 2 The value obtained by multiplying the value multiplied by / 3 to the power of 1/2 is defined as the film thickness unevenness index Rp (unit: mV). 2. The support for a heat transfer type thermal transfer recording image receiving material according to claim 1, wherein the polyolefin resin is a polyethylene resin, and the coating thickness of the resin is 4 μm to 10 μm. 3. The support for a heat transfer type thermal transfer recording image receiving material according to claim 1, wherein the polyolefin resin contains a titanium dioxide pigment. 4. The support for a heat transfer type thermal transfer recording image receiving material according to claim 1, 2 or 3, wherein the surface of the paper substrate opposite to the image receiving side is coated with a resin capable of forming a film. 5. The support for a heat transfer type thermal transfer recording image receiving material according to claim 4, wherein the resin capable of forming a film is a polyolefin resin.