JP2590192B2 - Image forming materials - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to an image forming material. More specifically, the present invention relates to an image forming material having excellent aesthetics such as sharpness and contrast of a formed image.

[Prior art] Conventionally, as a material for forming an image, a so-called photographic paper in which a polyethylene in which a white pigment such as titanium oxide is kneaded is provided as a water-resistant layer on a base paper and a photosensitive photographic emulsion layer is coated thereon. An image receiving paper for a thermal transfer printer in which an ink receiving layer is provided on a polyolefin synthetic paper (for example,
−51490).

Further, since the photographic paper is easily torn and does not have sufficient water resistance (water is absorbed from the end face), it has been proposed to use a thermoplastic resin as a base material for improving such defects. For example, an example in which titanium oxide and barium sulfate are blended in a thermoplastic resin (Japanese Patent Publication No. 56-4901), an example in which barium sulfate is blended in polyester (Japanese Patent Publication No. 60-30930), and an example in which titanium oxide is blended in polyester (Japanese Unexamined Patent Application Publication No. 61-118746).

[Problems to be Solved by the Invention] However, in the above-mentioned conventional technology, the image formed via the polyethylene layer lacks sharpness and contrast because the surface of the photographic paper is rough. Further, the base film in JP-B-56-4901, JP-B-60-30930, JP-A-61-118746, etc., is also an image in which surface quality is formed,
In other words, there is a lack of consideration regarding the sharpness and contrast of the photograph. Further, when barium sulfate is used, agglomeration is strong and dispersion is difficult, so that a defect easily occurs on the obtained film surface. Further, the polyester resin containing titanium oxide has poor light resistance, and therefore has a problem that it is easily yellowed and causes poor contrast.

Further, with respect to printer receiving paper, there is a problem that the image formed on the ink receiving layer is still unclear because the surface roughness of the synthetic paper is large.

The present invention solves this problem, using a polyester excellent in durability, water resistance, etc., the formed image is sharp,
It is an object of the present invention to provide an image forming material having a good contrast and the like and an excellent appearance.

[Means for Solving the Problems] The present invention provides a polyester having an average particle diameter of 0.05 to 1.5 μm.
a film containing 10 to 30% by weight of calcium carbonate based on the total weight, and melt-extruded and stretched.
An image forming material comprising a film having a Ra of 0.21 μm or less, a gloss of 35% or more, and a reflectance of 85% or more provided with an ink receiving layer for sublimation type thermal transfer on at least one side of a film. It is.

The polyester in the present invention may be any polyester as long as it can form a film. For example, polyethylene terephthalate, polytetramethylene terephthalate, polyethylene-0-oxobenzoate, poly-
1.4-cyclohexylene dimethylene terephthalate, polyethylene-2.6-naphthalenedicarboxylate and the like. Of course, these polyesters may be homopolyesters or copolyesters, and the copolymerization components include, for example, diol components such as diethylene glycol, neopentyl glycol and polyalkylene glycol, adibic acid, sebacic acid, phthalic acid, Isophthalic acid, 2.6-naphthalenedicarboxylic acid, 5
-Dicarboxylic acid components such as sodium sulfoisophthalic acid.

Further, various known additives such as an antioxidant and an antistatic agent may be added to the polyester. Polyethylene terephthalate is preferred as the polyester used in the present invention. The polyethylene terephthalate film is excellent in water resistance, durability, chemical resistance and the like.

In the present invention, examples of the calcium carbonate contained in the polyester include natural products and synthetic products, and any of them may be used. Further, for the purpose of improving the dispersion of calcium carbonate in the polyester, the surface may be treated with various organic substances.

The average particle size of the calcium carbonate is 0.05 to 1.5 μm, preferably 0.1 to 1.2 μm, more preferably 0.15 to
0.9 μm. If the average particle size is smaller than this range, the contribution to light scattering is small, and the underlayer of the obtained film becomes easy to see, resulting in poor contrast of the formed image, which is not preferable. In addition, dispersion in polyester is difficult, which is not preferable. On the other hand, if it is larger than this range, the formed image lacks sharpness, which is not preferable.

In the present invention, such calcium carbonate is 10 to 30% by weight of polyester based on the total weight. Preferably, 10-25 wt%
To be included. If the content is less than this range, the contrast of the formed image becomes poor, similarly to the case where the particle diameter is too small, which is not preferable. On the other hand, if it is more than this range, the particles are difficult to disperse, and the formed image tends to lack sharpness, which is not preferable.

Further, in the present invention, particles other than calcium carbonate, for example, oxides such as aluminum, silicon, and titanium may be contained as long as they do not impair image clarity and contrast, but the content of these particles is calcium carbonate. 1 /
4 or less is preferred. In other words, particles other than calcium carbonate,
For example, those containing a large amount of silicon dioxide, alumina, talc, barium sulfate or the like are difficult to disperse or cause coloring, and thus are likely to lack sharpness and contrast of an image.

The term “stretching” in the present invention refers to uniaxial or biaxial stretching, and biaxial stretching, which is excellent in mechanical strength and dimensional stability of the film, is preferred. Biaxial stretching includes sequential or simultaneous biaxial stretching according to a known method.

Surface roughness Ra of the film in the present invention is 0.21 μm or less, preferably 0.16 μm or less, more preferably 0.10 μm
It is as follows. If the surface roughness Ra is larger than this value, it is not preferable because the formed image lacks sharpness.

The glossiness of the film in the invention is at least 35%, preferably at least 40%, more preferably at least 45%. If the glossiness is smaller than this value, the amount of scattered light is too large and the formed image lacks sharpness, which is not preferable.

The reflectance of the film of the present invention is 85% or more, preferably 90% or more. If the reflectance is smaller than this value, the contrast of the formed image is lost, which is not preferable. Further, it is desirable that there is no portion where the reflectance in the visible region (wavelength 360 to 700 mm) is 80% or less.

In addition, it is preferable that the thickness of the film of the present invention is 50 to 300 μm. If the thickness of the film is smaller than this range, the stiffness as a substrate is too weak. On the other hand, if it is thicker than this range, it is too hard to handle.

Usually, the film of the present invention is provided with an image forming layer on at least one side. The image forming layer is particularly useful for an image receiving paper provided with an ink receiving layer for sublimation type thermal transfer. The ink receiving layer for sublimation-type thermal transfer is not particularly limited as long as it functions to receive the sublimation dye transferred from the thermal transfer sheet coated with the sublimation dye at the time of heating. For example, polyester-, polyurethane-, and polyamide-based resins having a relatively low glass transition temperature, styrene / maleic acid resins, and vinyl chloride resins having a highly polar group, and the like, and copolymers thereof can be mentioned. , A mixture may be used.

Next, a method for producing the image forming material of the present invention will be described, but the present invention is not limited to such an example.

Before the calcium carbonate in the present invention is contained in the polyester, the particle size of the calcium carbonate is adjusted. As the particle size adjusting means, pulverizing treatment, sand grinder treatment, classification and the like may be mentioned, and any means may be used, but in order to make the particle size distribution as sharp as possible, and furthermore, in order not to impair the sharpness of the formed image. Also the particle size
It is preferable that coarse particles of 10 μm or more are removed by a filter or the like.

As a method of incorporating the calcium carbonate of the present invention into the polyester, there are a method of adding at the time of polymerization of the polyester and a method of melt-kneading with the polyester.However, from the viewpoint of easy dispersion of calcium carbonate, the method of adding at the time of polymerization is preferred. More preferred. In causing the polyester to contain calcium carbonate, the calcium carbonate is treated with a metal soap, a coupling agent, or the like, or the polyester polymerization reaction system is phosphoric acid, phosphorous acid, phosphorus compounds such as phosphonic acid and derivatives thereof. Is added to further improve the dispersibility of calcium carbonate. If the dispersibility of the particles to be added is poor, the resulting film has a lumpy defect,
Even if the surface roughness Ra is within the range of the present invention, the formed image lacks sharpness. This is because the surface roughness Ra is obtained by detecting a part such as a film surface, and in many cases, a rugged defect scattered on the film surface cannot always be detected. Therefore, it is necessary to give due consideration to dispersion.

Further, the polyester of the present invention is usually used in the production of lithium, sodium, calcium, magnesium, manganese, zinc, cobalt, antimony, germanium,
If necessary, a metal compound catalyst such as titanium, an antioxidant, a pigment, a fluorescent brightener, a surfactant, an antistatic agent, and the like may be added. After that, the polymerization may be carried out by a method known in the art, but if the polymerization time is prolonged, or if additives or the like are added unnecessarily, the polymer tends to be colored, and the reflectance of the obtained film in the visible region decreases. As a result, dullness occurs and the formed image lacks contrast.

The intrinsic viscosity of the polymer chip obtained in this way is 0.42 to 0.4.
Preferably it is 75. If the intrinsic viscosity is smaller than this range, the resulting film is likely to be embrittled, while if larger than this range, the extrusion load is increased,
The stress at the time of stretching becomes too large and it is difficult to stretch.

The polymer chip obtained by the above polymerization is sufficiently dried in a vacuum, and then supplied to an extruder heated to 270 to 300 ° C., and formed into a sheet from a T-shaped die. At this time, there is no problem in mixing and adding a fluorescent whitening agent in the form of a master chip or a powder in order to emphasize the whiteness of the obtained film. Further, the film was cooled and solidified with a cooling drum having a surface temperature of 30 to 60 ° C. to obtain an unstretched sheet.
Guided to a group of preheated rolls heated to 120 ° C, stretched longitudinally,
Cool with rolls at 0 ° C. In this case, it is preferable that the film does not contact the roll in the stretched section. When stretched in contact with the roll, the film surface is scratched,
A ridge-like (streak-like) defect is likely to occur, and the formed image may lack sharpness. Subsequently, the longitudinally stretched film is guided to a tenter while holding both ends of the film with clips, and is horizontally stretched in an atmosphere heated to 90 to 140 ° C. The stretching ratio is 2 to 5 times in the longitudinal and transverse directions, and the area ratio (longitudinal stretching ratio × lateral stretching ratio) is 6 to 20 times. If the area magnification is smaller than this range, the obtained film is likely to have stretch unevenness, and the surface roughness Ra and glossiness are deteriorated,
The formed image lacks sharpness. On the other hand, if it is larger than this range, the film tends to be broken at the time of stretching, resulting in poor film-forming properties. In order to impart flatness, dimensional stability and the like of the biaxially stretched film in this manner, the film is heat-set at 150 to 230 ° C. in a tenter, uniformly cooled, cooled to room temperature, and wound. It is more preferable that the glossiness is further improved by treating with a calender roll or the like before winding.

By setting appropriate production conditions in this way, the film of the present invention can be obtained.

An image forming layer is provided on at least one side of the film, and the method may be applied by a known method such as bar coating or reverse coating. In this case, before providing the image forming layer, a surface activation treatment (for example, corona discharge treatment or the like) and / or an undercoat layer can be provided in advance.

[Measurement and Evaluation Methods] The measurement and evaluation methods used in the present invention are as follows.

(1) Average particle diameter The inorganic particles were dispersed in ethanol and measured using a centrifugal sedimentation type particle size distribution measuring device (CAPA500 manufactured by Horiba, Ltd.), and the volume average diameter was calculated to be the average particle diameter.

(2) Surface roughness Ra was measured with a stylus type surface roughness meter (ET-10, manufactured by Kosaka Laboratories) in accordance with Ra JIS-B-0601. The measurement magnification was 50,000 times, the measurement length was 1 mm, and the measured values of five measurements were averaged.

(3) Gloss The gloss meter (manufactured by Nippon Denshoku Industries Co., Ltd.) is used in accordance with Method 2 of JIS-Z-8741 (specular gloss at an incident angle of 60 degrees and a light receiving angle of 60 degrees).
VG-107) and the average of 10 measurements.

(4) Reflectance The reflectance in the visible region (360-700 mm) is continuously measured with Hitachi spectrophotometer type 323, and the reflectance (a%) at a wavelength of 450 nm is measured.
The value obtained by averaging the reflectance (b%) at a wavelength of 550 nm was defined as the reflectance.

Reflectivity = (a + b) / 2 Incidentally, a magnesium oxide white plate was used on the basis of a reflectance of 100%.

(5) Dispersibility of calcium carbonate in the polymer Insert 20mg of the polymer between two cover glasses, 285 ℃
After cooling with a melt press, the determination was made by microscopic observation.

；: Almost no aggregated particles are observed. (This is the object of the present invention.) Δ: Slightly aggregated particles are observed. (The object of the present invention is not achieved.) ×: Many aggregated particles are observed. (The object of the present invention is not attained.) (6) Evaluation Criteria for Formed Image An image is formed on an image-forming material having an image-forming layer provided on various films, and the number of n is set to ten, and the image sharpness and contrast are visually recognized. Was determined.

◎: very good (within the object of the present invention and particularly preferred) ；: good (within the object of the present invention and preferred) △: slightly poor (not attained the object of the present invention) ×; poor (the present invention [Example] Hereinafter, an embodiment of the present invention will be described based on examples and comparative examples.

Example 1 85 wt parts of dimethyl terephthalate, ethylene glycol
After transesterification of 60 wt parts with 0.09 wt parts of calcium acetate as a catalyst in accordance with a conventional method, trimethyl phosphate is used as a phosphorus compound so as to be 0.45 wt% with respect to the polymer.
Immediately after the addition of an ethylene glycol solution containing 10 wt%, calcium carbonate having an average particle size of 0.4 μm, which does not include those having a particle size of 10 μm or more, which has been subjected to sand grinder treatment and filtration, is added to 14 wt% based on the total weight of the polymer. To be
A 30 wt% ethylene glycol slurry was added, and then 0.03 parts by weight of antimony trioxide was added as a polymerization catalyst.
Thereafter, a polycondensation reaction was carried out at a high temperature under reduced pressure according to a conventional method to obtain polyethylene terephthalate having an intrinsic viscosity of 0.58. The dispersibility of calcium carbonate in the obtained polymer was good.

The obtained polymer was vacuum-dried at 180 ° C. for 4 hours, supplied to an extruder heated to 285 ° C. to form an unstretched sheet, and then preheated by a group of rolls having a preheating temperature of 80 to 98 ° C. After contact, the film was longitudinally stretched 2.8 times and cooled with a roll group at 25 ° C. Subsequently, both ends of the stretched film are gripped with clips and guided to a tenter, and then horizontally stretched three times in an atmosphere at 130 ° C., and then heat-fixed in an atmosphere at 220 ° C. and 3% in the horizontal direction.
To give a film having a thickness of 180 μm. The surface roughness Ra of this film was 0.041 μm, the glossiness was 71%, and the reflectance in the visible region was 94%.

Further, a polyester resin (Byron 20 manufactured by Toyobo Co., Ltd.) which is an ink receiving layer of a sublimation dye is further provided on the film.
0) 10 parts by weight, amino-modified silicone (Shin-Etsu Chemical K
F-393) 0.5 part by weight, epoxy-modified silicone (X-22-343 manufactured by Shin-Etsu Chemical Co., Ltd.) 0.5 part by weight was dissolved in toluene / methyl ethyl ketone = 1/90 part by weight and applied, and the solid content was 3 μm in thickness. A video image was printed by a video printer GZ-P10B / w manufactured by Sharp using the material formed in the above as an image forming material. The formed image was again excellent in sharpness and contrast and excellent in aesthetic appearance.

Examples 2 to 4 Comparative Examples 1 to 4 An image forming material was obtained in the same manner as in Example 1 except that the average particle diameter and the amount of calcium carbonate to be contained were changed. Table 1 shows their characteristic values and evaluation results as an image forming material. From these results, the average particle size of calcium carbonate added to the polyester, the amount added and the surface roughness Ra of the resulting film, the glossiness, the image formed by keeping the reflectance in the visible region within the scope of the present invention. It can be seen that the sharpness and contrast of the image become good.

Comparative Example 5 When a sharp color video print sheet using polypropyne synthetic paper as a base material was evaluated by the same printer as in Example 1, the formed image lacked sharpness.

[Effects of the Invention] The present invention uses a film having a specific range of the average particle diameter and the amount of calcium carbonate to be contained in the polyester, and the surface roughness Ra, glossiness, and reflectance in the visible region of the obtained film. Since the material is used as an image forming material, the following excellent effects can be obtained.

(A) The formed image is excellent in sharpness.

(B) The contrast of the formed image is excellent.

 ──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-62-286989 (JP, A) JP-A-1-173030 (JP, A) JP-A-60-21250 (JP, A) JP-A-61-26989 47235 (JP, A) JP-A-61-186957 (JP, A) JP-A-58-188865 (JP, A)

Claims (1)

(57) [Claims] An average particle size of the polyester is 0.05 to 1.5 μm.
a film containing 10 to 30% by weight of calcium carbonate based on the total weight, and melt-extruded and stretched.
An image-forming material comprising a film having a Ra of 0.21 μm or less, a gloss of 35% or more, and a reflectance of 85% or more, provided with an ink-receiving layer for sublimation-type thermal transfer on at least one side of the film.