JPH08112965A - Material to be recorded - Google Patents

Abstract

PURPOSE: To provide a material to be recorded adapted for ink jet which has excellent ink acceptance, no swelling of a surface layer, suitable dot diameter spreading and can satisfy the image quality of a recorded image. CONSTITUTION: A material to be recorded comprises a base material and an ink acceptance layer provided on the material, wherein the layer has a surface layer and an ink absorbing layer, the surface layer and the absorbing layer contain polyvinyl alcohol, and the degree of the saponification of the alcohol contained in the surface layer is lower than that of the alcohol contained in the absorbing layer.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a recording material suitable for use in an ink jet recording method, and particularly to a recording material which is excellent in ink receptivity, is excellent in drying property of a surface after printing, and achieves high image quality. The present invention relates to an image forming method. The image forming method in the present invention includes coloring the recording material.

[0002]

2. Description of the Related Art Ink jet recording methods include various ink (recording liquid) ejection methods, for example, an electrostatic suction method, a method in which a piezoelectric element is used to mechanically vibrate or mutate the recording liquid, and the recording liquid is heated. By firing and using the pressure to generate small droplets of ink and fly them, part or all of them are made to adhere to the recording material such as paper and fly to generate low noise and high-speed printing. , Has attracted attention as a recording method capable of multicolor printing.

As the ink for ink jet, one mainly containing water is used from the viewpoint of safety and recording characteristics, and polyhydric alcohol or the like is used for preventing clogging of nozzles and improving ejection stability. Often added.

As the recording material used in the ink jet recording method, conventionally, there is used ordinary paper or a recording material having a porous ink receiving layer provided on a base material called an ink jet recording paper. Came. However, with the improvement and spread of the performance of inkjet recording apparatuses such as high-speed recording and multicolor recording, more advanced and wide-ranging characteristics are required for recording materials. That is, as a recording material for inkjet recording for obtaining a high-resolution and high-quality recorded image, (1) the ink should be received by the recording material as quickly as possible. (2) Even if the ink dots overlap, the ink that has adhered later does not flow into the dots that have adhered before. (3) The ink droplets do not spread on the recording material, and the diameter of the ink dot does not become larger than necessary. (4) The shape of the ink dot is close to a perfect circle, and its circumference is smooth. (5) The OD (optical density) of the ink dot is high, and the area around the dot is not blurred. It is necessary to satisfy the basic requirements such as. Further, it is used for observing recorded images on a screen or the like by an optical device such as a slide or an OHP (overhead projector), a color separation plate for making a positive plate for color printing, a liquid crystal. And a CFM (color mosaic filter) used for a color display of the above. In the recording material for these applications, the transmitted light of the recorded image is a problem. Therefore, (6) it is required that the light-transmitting property, particularly the excellent linear transmittance, is weighted in consideration of the required performance of the above-mentioned general recording material for inkjet recording.

In particular, in order to increase the speed of ink absorption, many conventional recording materials for surface image observation are provided with a porous ink receiving layer on the surface, and the recording liquid is received in the porous voids, The method of fixing the recording material was used. However, the surface of the recording material was not glossy due to its porosity.

On the other hand, it has been attempted to use a water-absorbing polymer as the ink receiving layer. Although the water-absorbent polymer almost satisfies the water-accepting property and gloss in the ink, most of them are generally water-soluble, and the surface of the recording material swells when receiving the ink, and the surface layer of the recording material is exposed when it comes into contact with the recorded image. There is a problem that the image is peeled off and the recorded image is damaged. Also,
When a polymer alone is used for the surface layer, the surface tends to become non-porous, and non-volatile components such as polyhydric alcohol in the ink remain on the recording material surface for a long time after recording, and the ink drying and fixing time As it becomes longer, ink bleeding may occur,
Similarly to the above, when the recorded image is contacted, the recorded image is damaged. Therefore, at present, there is no known recording material capable of simultaneously receiving moisture and non-volatile components in the ink, having no swelling of the surface layer, and satisfying gloss and image quality at the same time.

[0007]

The object of the present invention is to:
It is an object of the present invention to provide a recording material suitable for ink jet which has excellent ink receptivity, does not swell the surface layer, and satisfies the gloss of the recording material and the image quality of the recorded image, and an image forming method using the same.

Another object of the present invention is to provide a recording material suitable for full-color ink jet which has excellent ink receptivity, does not swell the surface layer, and satisfies the gloss of the recording material and the image quality of the recorded image at the same time. Especially.

[0009]

The present invention relates to a recording material having a substrate and an ink receiving layer provided on the substrate, wherein the ink receiving layer is a surface layer and an ink absorbing layer. The polyvinyl alcohol contained in the surface layer and the ink absorbing layer both contain polyvinyl alcohol, and the saponification degree of the polyvinyl alcohol contained in the surface layer is lower than the saponification degree of the polyvinyl alcohol contained in the ink absorbing layer. Is a recording material.

The present invention will be described in detail below. The present invention is mainly characterized in that the saponification degree of polyvinyl alcohol (hereinafter referred to as PVA) contained in the surface layer of the ink receiving layer is lower than the saponification degree of PVA contained in the ink absorbing layer. The object of the invention is achieved. In addition, in the present specification, polyvinyl alcohol (hereinafter, PVA) is obtained by saponifying polyvinyl acetate, and may include a part which is not saponified, and saponification of polyvinyl alcohol (hereinafter, PVA). The degree means the degree of saponification of polyvinyl acetate.

The recording material of the present invention generally comprises a substrate as a support and an ink receiving layer (including an ink absorbing layer and a surface layer) provided on the surface thereof. Further, a water absorbing layer of polyvinyl alcohol, polyacrylic acid, polyurethane or the like may be provided between the ink absorbing layer and the substrate in order to enhance the water absorbing property of the recording material, if necessary. The ink receiving layer of the recording material of the present invention is a portion that receives ink from the recording means of the recording device or the recording device during recording. In general, the recording material receives the ink by the ink adhering to the surface of the ink receiving layer of the recording material entering into the fine voids in the structure of the ink receiving layer mainly by a dissolving or swelling action. Factors that greatly affect the ink reception of the ink receiving layer include the structure of the ink receiving layer and the physical properties of the material forming the ink receiving layer. That is, the structure of the ink receiving layer is a structure in which the ink easily penetrates, and the ink receiving layer has a void volume suitable for receiving and containing the ink. It is important that the material used has affinity with the ink.
Therefore, when the ink used is water-based, it is necessary to use a hydrophilic material as a part of the recording material that absorbs and receives the ink, that is, a material that constitutes the ink receiving layer. Very effective to get. Furthermore, it is important that the recording material that swells when absorbing the ink does not separate due to contact.

Further, the ink contains a polyhydric alcohol such as glycerin and diethylene glycol for the purpose of preventing nozzle clogging and adjusting the viscosity, and must accept not only water but also these non-volatile liquid media at the same time. I have to. Therefore, the ink receiving layer is required to have high affinity with these non-volatile media in addition to being hydrophilic.
Further, it is important that the ink is absorbed promptly and does not diffuse on the surface of the recording material, but on the other hand, if the ink dot diameter is too small, the image density decreases, so it is also necessary to spread the dot diameter appropriately.

The inventors of the present invention have earnestly studied in consideration of the various points as described above, and as a result, provided an ink receiving layer having a multilayer structure composed of a surface layer and an ink absorbing layer on a substrate, It was found that when defining the saponification degree of PVA contained, a recording material that satisfies the various conditions described above and simultaneously satisfies the gloss and the image quality of the recorded image can be obtained.

That is, in the ink receiving layer of the recording material of the present invention, by lowering the saponification degree of PVA of the surface layer, the speed of ink absorption on the surface layer of the recording material is increased, so that the ink dots of the ink dot are formed. Small diffusion and high image quality can be achieved.

Further, the PVA of the ink absorption layer is more than that of the surface layer.
By increasing the degree of saponification of the ink, a difference in ink absorption speed at the interface is generated, and appropriate dot spreading can be provided at the interface of the ink absorption layer.

Further, by lowering the saponification degree of PVA in the surface layer and enabling coating with an increased proportion of the organic solvent in the diluting liquid, the ink absorbing layer is peeled off due to swelling of water absorption during coating. Laminate coating can be performed without performing the above.

The degree of saponification of PVA in the present invention means the number of units of X represented by the following general formula (1),

[0018]

Embedded image That is, saponification degree = x / (x + y) × 100% (2). The above formula (1) does not represent a block polymer, but represents only the ratios of x and y.

The preferred range of the saponification degree in the present invention is a ratio K1 / of the saponification degree K1 of PVA contained in the surface layer and the saponification degree K2 of PVA contained in the ink absorbing layer.
K2 is preferably 0.3 or more and less than 1.0, and more preferably 0.6 or more and 0.9 or less. K1 / K2 is 0.3
If it is smaller, the absorption speed of the ink in the surface layer becomes slower, and dot bleeding is likely to occur. Further, if K1 / K2 is 1.0 or more, the spread of dots at the interface of the ink absorption layer cannot be sufficiently obtained, and thus it is difficult to obtain an image density sufficient to achieve high image quality in the present invention.

In the present invention, the cause of the change in the ink absorption rate depending on the saponification degree is not clear, but it is presumed as follows. That is, by lowering the degree of saponification, formula (1)
It is considered that since the number of remaining vinyl acetate units is increased, the affinity with the polyhydric alcohols in the ink is increased and the absorption speed of the ink is increased.

As the base material used as the support of the ink receiving layer in the present invention, any of the conventionally known base materials such as transparency and opacity can be used. Suitable examples of the transparent base material include, for example, Examples thereof include polyester resin, diacetate resin, triacetate resin, acrylic resin, polycarbonate resin, polyvinyl chloride resin, polyimide resin, cellophane, film or plate such as celluloid, and glass plate. Preferred examples of the opaque base material include general paper, cloth, wood, metal plate, synthetic paper and the like, as well as the above-mentioned transparent base material subjected to opacity treatment by a known means.

Further, a resin coating may be applied to the back surface of the above-mentioned base material to prevent the sheet from bending due to volume contraction after printing. Usable resins include general thermoplastic resins and thermosetting resins. Alternatively, the same coat layer as the ink receiving layer formed on the surface may be provided.

As a method for forming the ink receiving layer, the coating liquid is prepared by dissolving or dispersing the PVA of the present invention or a mixture of the PVA and the other polymer in an appropriate solvent.
The coating liquid is applied onto a translucent substrate by a known method such as a roll coating method, a rod bar coating method, a spray coating method, a die coating method, a lip coating method, etc., and then rapidly dried to form an ink. A method in which an absorption layer is used and a surface layer is applied in the same manner is preferable. Further, as another method, a method of hot-melt coating the PVA of the present invention alone or a mixture of the PVA and another polymer, hydrolysis of metal alkoxide-
A method of forming a film by a sol-gel reaction utilizing a polymerization reaction,
Alternatively, a method may be used in which an ink receiving layer having only one end is formed from the above material and the sheet is laminated on the base material.

In the method as described above, the PVA of the present invention is used.
Preferred examples of other polymers that can be used by mixing with are natural proteins such as albumin, gelatin, casein, starch, cationic starch, gum arabic and sodium alginate,
Polyamide, polyacrylamide, polyvinylpyrrolidone, quaternized polyvinylpyrrolidone, polyethyleneimine, polyvinylpyridium halide, melamine resin, polyurethane, polyvinyl alcohol, polyester, sodium polyacrylate, SBR latex, NBR latex, polyvinyl formal, polymethylmethacrylate, Synthetic resins such as polyvinyl butyral, polyacrylonitrile, polyvinyl chloride, polyvinyl acetate, phenol resin, and alkyd resin are mentioned.
Species or more are used as desired.

Further, in the ink receiving layer of the present invention, it is preferable to disperse inorganic particles such as SiO ₂ and Al ₂ O _{3 in} order to increase the ink absorption rate. As a preferable mixing ratio with the PVA, the inorganic particle component is 80 to 3% by weight with respect to 20 to 97% by weight of PVA in each layer, and more preferably 50 to 95% by weight of the PVA and 50 to 5% of the inorganic particle component. % By weight. When the content of the inorganic particles is more than 80%, white turbidity of the film becomes remarkable and transparency is deteriorated. If the amount of the inorganic particles is less than 3% by weight, it is difficult to obtain the effect of increasing the ink absorption rate.

Fillers such as clay, talc, diatomaceous earth, calcium carbonate, calcium sulfate, barium sulfate, aluminum silicate, synthetic zeolite, zinc oxide, lithopone and satin white can also be dispersed in the ink receiving layer. .

The recording material of the present invention is formed by using the above-mentioned main materials. In order to make the recording material as a whole translucent, both the base material and the ink receiving layer are transparent. It is preferably light-sensitive. The recording material of this aspect is
OH for projecting recorded images on a screen etc. by optical equipment
It is used in the case of P and the like, and is useful as a recording material for observation of transmitted light.

Such a translucent recording material forms a translucent ink receiving layer from PVA alone, a mixture of PVA and inorganic particles, or a mixture of other translucent polymers as described above. It can be adjusted by

The term "translucency" as used in the present invention means that the linear transmittance of the recording material is 10% or more. Linear transmittance is 1
If it is 0% or more, for example, it is possible to project the recorded image on the screen by OHP and observe the details of the recorded image clearly.

The linear transmittance Τ% referred to here means that the light enters the sample vertically, passes through the sample, passes through the slit on the light receiving side on the extension line of the incident light path at least 8 cm or more from the sample, and is detected by the detector. The spectral transmittance of the linear light received by is measured using, for example, a 323 Hitachi autograph spectrophotometer (manufactured by Hitachi, Ltd.), and the measured spectral transmittance indicates the Y value of the tristimulus value of the color. Is obtained and is a value obtained from the following equation.

Τ = Y / Y ₀ × 100 (3) Τ: Linear transmittance Y: Sample Y value Y ₀ : Blank Y value Therefore, the linear transmittance referred to in the present invention is for linear light. Yes, diffuse transmissivity (an integrating sphere is provided behind the sample to obtain the transmissivity including diffused light) and opacity (the back of the sample is backed with white and black It is different from the method of evaluating the translucency by diffused light such as (obtained from the ratio).

Since the behavior of linear light is a problem in devices using optical technology, in evaluating the translucency of the recording material to be used in those devices, the linearity of the recording material is evaluated. Obtaining the light transmittance is particularly important.

For example, when observing a projected image with OHP,
In order to obtain a clear and easy-to-see image with high contrast between the recorded part and the non-recorded part, the non-recorded part in the projected image is bright, that is, the linear transmittance of the non-recorded material is at a certain level or more. Is required. In the test using the OHP test chart, the linear transmittance of the recording material is 2% or more in order to obtain an image suitable for the above purpose, and 10% or more in order to obtain a clearer image. Needed. Therefore, the recording material suitable for this purpose is
It is necessary that the linear transmittance is 10% or more.

The glossy surface referred to in the present invention means
It means that the 45 ° specular gloss based on JIS Z8741 is 30% or more. This type of recording material is particularly useful as a recording material for observing the back side image having excellent surface gloss, full color and sharpness. The recording material in this embodiment may be transparent or opaque, and any of the above-mentioned transparent and opaque substrates can be used.
Further, the ink receiving layer formed on these substrates may be transparent or opaque. The materials and methods used for forming the ink receiving layer are the same as those described above, but the above-mentioned fillers are added to the extent that the ink receiving layer becomes opaque as long as the surface of the ink receiving layer can maintain smoothness. You can use it. In addition to the above-mentioned coating method, a cast coating method may be used, or a gloss roll may be used for glossing, if necessary. In the present invention as described above, the thickness of the ink receiving layer formed on the substrate is usually 1 to 100.
It is about μm, preferably about 3 to 30 μm.

Although the present invention has been described above by exemplifying typical aspects of the recording material of the present invention, the recording material of the present invention is not of course limited to these aspects. In any case, the ink receiving layer contains a dispersant,
Various known additives such as fluorescent dyes, pH adjusters, thickeners, lubricants, preservatives and surfactants can be included. The recording material of the present invention does not necessarily have to be colorless and may be a colored recording material.

Hereinafter, the method of the present invention will be described in more detail with reference to Examples. In the text, parts are based on weight.

[0037]

【Example】

(Example) 1 Coating liquid (1) Polyacrylic acid (20% aqueous solution) 62.5 parts LiOH 10% aqueous solution 10.7 parts Benzylamine 9.3 parts PVA (10% aqueous solution, saponification degree 98%) 20 Part MeOH 10 parts coating liquid (2) ethyl silicate 2 parts 2N-hydrochloric acid 0.02 parts MeOH 28.5 parts 100 μm thick polyethylene terephthalate film (manufactured by Toray) is used as a translucent substrate, and on this film Then, a polyurethane resin was applied by a roll coating method to a film thickness of about 0.5 μm and dried to obtain a support. A solution prepared by mixing the coating liquids (1) and (2) having the above composition on the support is applied by an applicator so that the film thickness after drying is 25 μm, and dried at 100 ° C. for 10 minutes. Then
A film coated with the ink absorbing layer was obtained.

On the obtained coated film, a coating liquid (3) having the following composition was applied as a surface layer by a die coating method so that the film thickness after drying would be 26 μm as a whole. Dry at 110 ° C for 10 minutes,
The recording material of the present invention was obtained. Coating liquid (3) PVA (5% aqueous solution, saponification degree 80%) 40 parts SiO ₂ (5% aqueous solution) 8 parts Al ₂ O ₃ (5% aqueous solution) 10 parts MeOH 42 parts The obtained recording material is It was colorless and transparent. For this recording material, an inkjet copy machine P made by Canon
PIXELJET using ink for IXELJET
Inkjet recording was carried out by (product name).

As a result, the surface layer was not peeled off even if it came into contact with the recorded image immediately after printing, and the ink on the surface of the recorded image was dried within 2 minutes after printing. Furthermore, there was no bleeding of the dots, the reproduction was good, and no streaks were observed in the solid area. Table 1 shows the evaluation results. The measurement of each evaluation item in Table 1 was performed according to the following method. (1) As for the ink fixing time, after recording, the recording material is left at room temperature, plain paper is pressed against the recorded image with a pressure of 0.5 kg / cm ² , and the ink and the peeling part of the surface layer adhere to the paper. The time to stop doing was measured. (2) OHP suitability is measured as a typical example of optical equipment, and a recorded image is projected on a screen by OHP,
It was judged by visual observation, the non-recording area was bright, and the OD (optical density) of the recorded image was high.
O for which a clear and easy-to-see projection image with high contrast can be obtained, for which the non-recording area is slightly dark, the OD of the recorded image is slightly low, and lines with a pitch width of 0.5 mm and a thickness of 0.25 mm cannot be clearly identified. Δ: The non-recorded area is considerably dark, the OD of the recorded image is considerably low, the pitch width is 1 mm, and the thickness is 0.
Those in which the line of 3 mm could not be clearly discriminated or those in which the non-recorded portion and the recorded image were indistinguishable were marked with x. (3) The linear transmittance was measured by measuring the spectral transmittance using a 323 Hitachi self-recording spectrophotometer (manufactured by Hitachi Ltd.), keeping the distance from the sample to the light receiving side mud at about 9 cm.
It was determined by the above formula (1). (4) For gloss, the 45 ° specular gloss of the surface of the recording material was measured based on JIS Z874-1.

(Example 2) Coating liquid (4) Polyvinylpyrrolidone 70 parts PVA (10% aqueous solution, saponification degree 90%) 20 parts MeOH 10 parts Coating liquid (4) on the support of Example 1 Application and drying were carried out in the same manner as in Example 1 to obtain an ink absorbing layer coat film having a film thickness of 26 μm. A coating solution having the same composition as that of the coating solution (3) except that the saponification degree of PVA was 75% was applied as a surface layer on the obtained coat film in the same manner as in Example 1 and dried. A recording material having a total film thickness of 27 μm was obtained. The obtained recording material was colorless and transparent. The recording material was evaluated in the same manner as in Example 1, and as a result, good results were obtained in the same manner as in Example 1.

(Example 3) A composition similar to that of the coating liquid (3) except that the saponification degree of PVA was set to 60% as a surface layer on the coat film coated with the ink absorbing layer in the same manner as in Example 1. The coating liquid was applied in the same manner as in Example (1) to obtain a recording material having a total film thickness after drying of 26 μm. The obtained recording material was colorless and transparent. This recording material was evaluated in the same manner as in Example 1, and as a result, Example 1 was obtained.
Good results were obtained as well.

Example 4 PVA on the support of Example 1
A coating solution having the same composition as the coating solution (1) except that the saponification degree is 85% is applied and dried in the same manner as in Example 1 to obtain a film thickness of 26 μ.
m ink absorption layer. PVA on the ink absorption layer
Coating was performed in the same manner as in Example (1) except that the saponification degree was set to 80% to obtain a recording material having a dry film thickness of 27 μm as a whole. The obtained recording material was colorless and transparent. The recording material was evaluated in the same manner as in Example 1, and as a result, good results were obtained in the same manner as in Example 1.

(Example 5) An art paper was used as a base material, and the coating liquid 1 of Example 1 was applied in the same manner as in Example 1 so that the film thickness after drying was 25 μm as a whole.・
After drying, apply the following coating solution to a film thickness of 26μm.
Was applied and dried in the same manner as in Example 1. Coating liquid (2) PVA (5% aqueous solution, saponification degree 80%) 25 parts Polyvinylpyrrolidone 45 parts Al ₂ O ₃ (5% aqueous solution) 3 parts SiO ₂ (5% aqueous solution) 2 parts MeOH 50 parts Obtained The recording material was white and glossy. The recording material was evaluated in the same manner as in Example 1, and as a result, good results were obtained in the same manner as in Example 1.

Comparative Example 1 Coating liquid (6) Polyvinyl acetate (5% aqueous solution) 40 parts SiO ₂ (5% aqueous solution) 8 parts Al ₂ O ₃ (5% aqueous solution) 10 parts MeOH 42 parts Example 1 The coating liquid (6) was applied and dried as a surface layer on the ink absorbing layer obtained in the same manner as in Example 1. The obtained recording material was colorless and transparent. The recording material was evaluated in the same manner as in Example 1. As a result, it was found that ink adhered to the paper even after 7 minutes or more after printing.

(Comparative Example 2) An ink absorbing layer was coated in the same manner as in Example 1 using a liquid having the same composition as the coating liquids (1) and (2) except that the saponification degree of PVA was 50%. Worked and dried. On the obtained ink absorption layer, PVA was used as a surface layer.
A liquid having the same composition as the coating liquid (3) except that the saponification degree was set to 100% was applied and dried in the same manner as in Example 1. The obtained recording material was colorless and transparent. The recording material was evaluated in the same manner as in Example 1. As a result, it was found that ink adhered to the paper even after 7 minutes or more after printing.

[0046]

[Table 1]

[0047]

As described above, the present invention comprises a substrate,
In a recording material having an ink absorbing layer provided on the substrate and an ink receiving layer consisting of a surface layer, the saponification degree of polyvinyl alcohol contained in the surface layer of the ink receiving layer is determined by the above ink absorption. By lowering the saponification degree of the polyvinyl alcohol contained in the layer, it is excellent in ink receptivity, has no swelling of the surface layer, has a suitable spread of the dot diameter, and is suitable for an inkjet that satisfies the image quality of a recorded image. A recording material can be provided.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor ▲ Sakaki ▼ Haruo Tetsuro 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc.

Claims (3)

[Claims] 1. A recording material comprising a base material and an ink receiving layer provided on the base material, wherein the ink receiving layer comprises a surface layer and an ink absorbing layer, and the surface layer and the ink absorbing layer. A recording material for recording characterized in that the saponification degree of polyvinyl alcohol contained in both of the layers and contained in the surface layer is lower than the saponification degree of polyvinyl alcohol contained in the ink absorbing layer. . 2. The ratio K1 / K2 of the saponification degree K1 of polyvinyl alcohol contained in the surface layer and the saponification degree K2 of polyvinyl alcohol contained in the ink absorbing layer is 0.3 or more and less than 1.0. The recording material according to claim 1, wherein the recording material is a recording material. 3. An image forming method, wherein an image is formed on the recording material according to claim 1 or 2 by an inkjet method.