JP3017805B2 - Inkjet recording sheet - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an ink jet recording sheet mainly using an aqueous ink. More specifically, the present invention relates to an ink jet recording sheet from which an excellent image can be obtained.

2. Description of the Related Art In an ink jet recording method, fine droplets of ink are made to fly by various operating principles and adhere to a recording sheet such as paper, thereby recording an image or a character. Inkjet printers are notable for their high-speed printability and low-noise properties, great flexibility in recording patterns, and no need for development-fixing, and that they can form complex images accurately and quickly. In recent years, it has rapidly spread in various applications as a hard copy creation device for image information such as characters and various figures created by a computer. Also, by using a plurality of ink nozzles, it is easy to perform multicolor recording. The color image formed by the multi-color ink jet method can obtain a record comparable to the multi-color printing by the plate making method and the printing by the color photographic method, and in applications where the number of copies is small, It is being widely used because it is cheaper than photographic technology. In recent years, the fields of application of ink jet printers that have attracted particular attention include full color image recording such as production of color printing plates in the printing field where images close to photographs are required, and output of design images in the design department. Furthermore,
The image information created by the computer is recorded on a transparent recording sheet by an inkjet printer, and this is
It is also used as a manuscript of an (overhead projector) for presentations at conferences and the like.

As the recording sheet used in the ink jet recording system, efforts have been made in terms of apparatuses and ink compositions so that high quality paper for writing or coated paper or coated paper can be used. However, as the performance of ink jet recording apparatuses has been improved and the applications thereof have been increased, such as higher speed, higher definition, and full color, recording sheets have been required to have more advanced characteristics. That is, as the recording sheet, the density of the print dots is high, the color tone is bright and vivid, the ink is absorbed quickly, the ink does not flow or bleed even when the print dots overlap, It is required that the diffusion in the horizontal direction is not unnecessarily large and that the periphery is clear and not blurred. In particular, in the case of color recording,
In addition to monochromatic recording of magenta, cyan, and black, multicolor recording in which these colors are superimposed is performed, and extremely strict performance is required to further increase the amount of ink adhered.

Further, when a conventional ink absorbing layer is used for OHP, there is a problem that even if a transparent support is used, the porous ink absorbing layer deteriorates light transmittance. Further, when the surface of the ink absorbing layer is non-porous, the light transmittance is improved, but due to poor aqueous ink receptivity, the ink remains on the sheet surface for a long time after image recording and printing. When the sheet is conveyed in the printer, a problem occurs that the ink is rubbed and the image is stained.

In order to solve such problems, many ink jet recording sheets provided with a transparent ink absorbing layer having high ink receptivity have been proposed. For example, JP-A-60-168651
JP-A-60-262685 discloses the use of hydroxyethylcellulose, JP-A-61-181679 discloses the use of a mixture of carboxymethylcellulose and polyethylene oxide, JP-A-61-193879 discloses the use of a mixture of water-soluble cellulose and polyvinylpyrrolidone,
JP-A-62-263084 proposes a receiving layer formed from a gelatin aqueous solution having a specific pH, and JP-A-1-146784 proposes the use of a mixture of gelatin and a surfactant.

The ink jet recording sheets described in these publications are excellent in light transmittance and improved in ink receptivity, but are still insufficient, in particular, the dot reproducibility is insufficient, and a high-quality color hard disk is used. It could not be used as copy material.

European Patent Publication No. 380133 describes a recording medium and an image forming method using the same. The recording medium includes a base material and an ink receiving layer provided on the base material, and the ink receiving layer contains a reaction product of a gelling agent and a coupling agent. In the image forming method, an image is formed by applying inkjet recording to the recording medium.

European Patent Publication No. 445372 discloses a recording medium for inkjet recording. The recording medium includes a polyolefin-coated substrate having an ink receiving layer formed on an upper surface thereof, and the ink receiving layer contains a mixture of gelatin and rice starch.

An object of the present invention is to provide an excellent high-quality inkjet recording sheet.

As the ink for ink jet recording, an ink mainly containing water and a polyhydric alcohol as a main component is used in order to prevent clogging of the ink in the conduits and nozzles in the printer head and to improve discharge characteristics. In order to obtain high quality ink jet recording, it is important that the ink receiving layer absorbs such ink quickly and does not diffuse it.

DISCLOSURE OF THE INVENTION The present inventors have conducted intensive studies to solve the above-mentioned problems, and as a result, by providing a specific ink receiving layer on a support, it has been found that a high-quality inkjet recording sheet can be obtained. I found it.

In the present invention, in the ink jet recording sheet provided with an ink receiving layer on a support, the ink receiving layer,
Low molecular weight gelatin having a molecular weight of 100,000 or less is solid at 30% by weight or more of the total solid content constituting the ink receiving layer, and mucochloric acid is 0.1 to 1% by weight based on the gelatin content at a solid content, and the molecular weight is 100,000. An ink jet recording sheet containing a component comprising carboxymethyl cellulose having a degree of etherification of 1 or less is provided below.

Gelatin contained in the ink receiving layer has a molecular weight of 10
Less than 10,000 are used. If the molecular weight exceeds 100,000, the compatibility with carboxymethyl cellulose deteriorates, and the uniformity of the image density of the ink receiving layer decreases.

As the gelatin, any gelatin can be used as long as it is made from animal collagen, but gelatin obtained from collagen obtained from pig skin, cow skin, and cow bone is preferable. Further, the kind of gelatin is not particularly limited, but lime-treated gelatin, acid-treated gelatin, gelatin derivatives (for example, JP-B-38-4854, JP-B-39-5514, JP-A-40-12237, No. 42-26345, U.S. Pat.No. 2,525,573, No. 2,594,293, No. 2614928
No. 2763639, No. 3118766, No.
Gelatin derivatives described in JP-A-3132945, JP-A-3186846, JP-A-3231553, British Patent No. 861414, JP-A-1033189, etc.) can be used alone or in combination.

The jelly strength of gelatin (based on the PAGI method and a bloom-type jelly strength meter) is preferably 150 g or more, particularly preferably 200 to 300 g.

The coating amount of the ink receiving layer is not particularly limited, but is preferably 3 to 50 g / m ² as a solid content, more preferably 5 to 30 g / m ^2.
It is. When the coating amount of the ink receiving layer is less than 3 g / m ² , the ink receiving property is poor, and the ink overflows from the receiving layer after printing. If it exceeds 50 g / m ² , the ink receptivity is improved, but problems such as cracking and curling of the ink receiving layer occur.

The ratio of mucochloric acid to gelatin is 0.
It is preferably from 1 to 1.0% by weight. When the proportion of mucochloric acid is less than 0.1% by weight, the coating of the receiving layer is insufficiently cured, and the receiving layer may flow out after printing.
If it exceeds 1.0% by weight, the ink receptivity is poor and the dot reproducibility deteriorates.

Carboxymethyl cellulose has a molecular weight of 100,000 or less,
The degree of etherification is 1 or less. If the molecular weight exceeds 100,000 or the degree of etherification exceeds 1%, the viscosity is high,
The coatability deteriorates.

The ratio of carboxymethylcellulose to gelatin is not particularly limited within the scope of the present invention,
To improve ink receptivity and dot reproducibility, the weight ratio of carboxymethylcellulose to gelatin was increased from 5/95 to 70/3.
It is preferably in the range of 0, more preferably in the range of 10/90 to 60/40.

A surfactant may be added to the ink receiving layer in order to improve dot reproducibility in addition to the binder. The surfactant used may be any of anionic, cationic, nonionic and betaine types, and may be of low molecular weight or high molecular weight. One or two or more surfactants are added to the ink receiving layer coating solution. When two or more surfactants are used in combination, an anionic surfactant and a cationic surfactant are used in combination. It is not preferable. The amount of the surfactant added is the solid content of the binder that constitutes the ink receiving layer.
0.001 g to 5 g is preferable for 100 g, and more preferably 0.1 g to 5 g.
01-3g.

In the ink receiving layer, in addition to the above-described surfactant, inorganic pigments, coloring dyes, coloring pigments, fixing agents for ink dyes, ultraviolet absorbers, antioxidants, pigment dispersants, defoamers, leveling agents, Various known additives such as a preservative, a fluorescent brightener, a viscosity stabilizer, and a pH adjuster can also be added.

As a method of applying the ink receiving layer coating liquid, for example, a commonly used coating method such as a slide hopper method, a curtain method, an extrusion method, an air knife method, a roll coating method, and a rod bar coating method is used.

The ink receiving layer is provided on at least one side of the support, but may be provided on both sides of the support for the purpose of preventing curling.

The thickness of the polyester film that can be used as the support is not particularly limited, but is preferably about 10 to 200 μm from the viewpoint of handling properties and suitability for paper passing of a printer.

The thickness of the polyolefin resin-coated paper that can be used as a support is not particularly limited, but is preferably about 50 to 300 μm from the viewpoint of handleability and paper passing suitability of a printer.

The base paper for the resin-coated paper is not particularly limited, and a commonly used paper can be used. However, for example, a smooth base paper used for a photographic support is preferable. As the pulp constituting the base paper, a natural pulp, a recycled pulp, a synthetic pulp, or the like is used alone or in combination of two or more. The base paper is blended with additives generally used in papermaking, such as a sizing agent, a paper strength enhancer, a filler, an antistatic agent, a fluorescent whitening agent, and a dye. Further, a surface sizing agent, a surface strengthening agent, a fluorescent whitening agent, an antistatic agent, a dye, an anchoring agent and the like may be applied on the surface.

The base paper is preferably one having good surface smoothness such as compression by applying a pressure with a calender or the like during or after papermaking, and its basis weight is preferably 30 to 250 g / m ² .

As the polyethylene resin, low density polyethylene, medium density polyethylene, high density polyethylene or a mixture thereof can be used. The low-density polyethylene referred to here has a density of 0.915 to 0.930 g / cm ³ and is usually produced by a high-pressure method. On the other hand, high-density polyethylene has a density of 0.950 g / cm ³ or more, and is usually produced by a low-pressure method or a medium-pressure method. These polyethylene resins having various densities and melt flow rates can be used alone or in combination of two or more.

The configuration of the resin layer of the resin-coated paper may be a single layer or a multilayer of two or more layers. Also in this case, the above-mentioned polyolefin resins can be used alone or in combination of two or more. Further, the respective layers of the multilayer may have different compositions or the same composition. As a method of forming a multilayer resin layer, any of a coextrusion coating method and a sequential coating method may be adopted.

The thickness of the coating resin layer of the resin-coated paper is not particularly limited, but it is generally coated to a thickness of 5 to 50 μm on the surface only or on both front and back surfaces.

In the resin of the resin-coated paper, white pigments such as titanium oxide, zinc oxide, talc and calcium carbonate, fatty acid amides such as stearamide and arachidic amide, zinc stearate, calcium stearate, aluminum stearate and magnesium stearate are included. Fatty acid metal salts such as
Antioxidants such as Irganox 1010 and Irganox 1076; blue pigments and dyes such as cobalt blue, ultramarine blue, cecilian blue, and phthalocyanine blue; magenta pigments and dyes such as cobalt violet, fast violet, and manganese purple; and fluorescent whitening agents And various additives such as an ultraviolet absorber can be appropriately combined and added.

The resin-coated paper is produced by a so-called extrusion coating method in which a heated and melted polyethylene resin is cast on a running base paper. Further, in order to improve the adhesiveness between the resin and the base paper, it is preferable to perform an activation treatment such as a corona discharge treatment or a flame treatment on the base paper before coating the resin on the base paper. The surface (surface) of the support on which the ink receiving layer is applied,
Depending on its use, it has a glossy surface, a matte surface, and the like, and a glossy surface is particularly preferably used. It is not always necessary to coat the back surface with a resin, but it is preferable to coat the resin from the viewpoint of curling prevention. The back surface is usually a matte surface, and the front surface or, if necessary, both the front and back surfaces can be subjected to an activation treatment such as a corona discharge treatment or a flame treatment.

The support may be provided with an antistatic or anti-curl backcoat layer to improve transportability. In the back coat layer, an inorganic antistatic agent, an organic antistatic agent, a hydrophilic binder, a latex, a curing agent, a pigment,
Surfactants and the like can be appropriately combined and added.

In the present invention, the gelatin absorbs the ink quickly and prevents the drying and fixing time from becoming long due to the ink remaining on the sheet surface for a long time. In addition, the amount of mucochloric acid added is 0.1 to
By limiting the amount to 1.0% by weight, the degree of crosslinking of gelatin is controlled to impart appropriate water absorption and water resistance. Further, carboxymethylcellulose has an effect of preventing excess diffusion of ink dots by suppressing swelling of the gelatin film.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail with reference to examples, but the contents of the present invention are not limited to the examples. In addition, "parts" means parts by weight.

Example 1 A resin composition consisting of 85 parts by weight of low-density polyethylene and 15 parts by weight of titanium dioxide was applied to the surface of a base paper having a basis weight of 100 g / m ^{2 made} of LBKP at 25 g / m ² , and the high-density polyethylene was applied to the back side.
A resin composition comprising 50 parts by weight and 50 parts by weight of low-density polyethylene was applied at 20 g / m ² to prepare a resin-coated paper. After corona-treating the surface of the resin-coated paper, an ink receiving layer coating solution having the following composition was applied by an extrusion method so that the weight after drying was 8 g / m ² . Immediately set to cool for 10 seconds, then pass through a drying zone that gradually raises the temperature while adjusting the temperature and humidity, and control the temperature and humidity of the drying zone so that the surface wet bulb temperature is 20 ° C or less, and inkjet recording A sheet was prepared.

(Ink receiving layer formulation 1) Low molecular weight gelatin (molecular weight 95,000) 50 parts Carboxymethyl cellulose (molecular weight 80,000, degree of etherification 0.8) 50 parts Mucochloric acid 0.3 part Example 2 Same as Example 1 on the support of Example 1 Then, an ink receiving layer coating liquid having the following composition was applied to prepare an ink jet recording sheet.

(Ink receiving layer composition 2) Low molecular weight gelatin (molecular weight 70,000) 30 parts Carboxymethyl cellulose (molecular weight 80,000, degree of etherification 0.8) 70 parts mucochloric acid 0.2 part Example 3 On the support of Example 1, in the same manner as in Example 1 An ink receiving layer coating solution having the following composition was applied to prepare an ink jet recording sheet.

(Ink receiving layer formulation 3) Low molecular weight gelatin (molecular weight 70,000) 50 parts Carboxymethyl cellulose (molecular weight 80,000, degree of etherification 0.8) 50 parts Mucochloric acid 0.05 part Example 4 On the support of Example 1, in the same manner as in Example 1 An ink receiving layer coating solution having the following composition was applied to prepare an ink jet recording sheet.

(Ink receiving layer composition 4) Low molecular weight gelatin (molecular weight 70,000) 50 parts Carboxymethyl cellulose (molecular weight 100,000, degree of etherification 1.0) 50 parts Mucochloric acid 0.5 part Example 5 On the support of Example 1, in the same manner as in Example 1 An ink receiving layer coating solution having the following composition was applied to prepare an ink jet recording sheet.

(Ink receiving layer composition 5) Low molecular weight gelatin (molecular weight 70,000) 50 parts Carboxymethyl cellulose (molecular weight 100,000, degree of etherification 1.0) 50 parts Mucochloric acid 0.3 part Example 6 In Example 1, the resin-coated paper used as a support was used. thickness
In the same manner as in Example 1 except that the film was changed to a 100 μm polyethylene terephthalate film, an ink receiving layer coating solution having the following composition was applied to prepare an inkjet image receiving sheet.

(Ink receiving layer formulation 6) Low molecular weight gelatin (molecular weight 70,000) 50 parts Carboxymethyl cellulose (molecular weight 80,000, degree of etherification 0.8) 50 parts Mucochloric acid 0.3 part Example 7 On the support of Example 1, in the same manner as in Example 1 An ink receiving layer coating solution having the following composition was applied to prepare an ink jet recording sheet.

(Ink receiving layer formulation 7) Low molecular weight gelatin (molecular weight 120,000) 50 parts Carboxymethyl cellulose (molecular weight 80,000, degree of etherification 0.8) 50 parts Mucochloric acid 0.3 part Example 8 On the support of Example 1, in the same manner as in Example 1 An ink receiving layer coating solution having the following composition was applied to prepare an ink jet recording sheet.

(Ink receiving layer formulation 8) Low molecular weight gelatin (molecular weight 70,000) 20 parts Carboxymethyl cellulose (molecular weight 80,000, degree of etherification 0.8) 80 parts Mucochloric acid 0.1 part Example 9 On the support of Example 1, in the same manner as in Example 1 An ink receiving layer coating solution having the following composition was applied to prepare an ink jet recording sheet.

(Ink receiving layer formulation 9) Low molecular weight gelatin (molecular weight 70,000) 50 parts Carboxymethyl cellulose (molecular weight 80,000, degree of etherification 0.8) 50 parts Mucochloric acid 0.04 part Example 10 On the support of Example 1, in the same manner as in Example 1 An ink receiving layer coating solution having the following composition was applied to prepare an ink jet recording sheet.

(Ink receiving layer composition 10) Gelatin (molecular weight 70,000) 50 parts Carboxymethyl cellulose (molecular weight 80,000, degree of etherification 0.8) 50 parts Mucochloric acid 0.6 part Example 11 On the support of Example 1, the same as Example 1 The coating liquid of the ink receiving layer was applied to prepare an ink jet recording sheet.

(Ink receiving layer composition 11) Low molecular weight gelatin (molecular weight 70,000) 50 parts Carboxymethyl cellulose (molecular weight 120,000, degree of etherification 0.8) 50 parts Mucochloric acid 0.3 part Example 12 On the support of Example 1, the same as in Example 1 Then, an ink receiving layer coating liquid having the following composition was applied to prepare an ink jet recording sheet.

(Ink receiving layer formulation 12) Low molecular weight gelatin (molecular weight 70,000) 50 parts Carboxymethyl cellulose (molecular weight 80,000, degree of etherification 1.2) 50 parts Mucochloric acid 0.3 part For each sheet obtained as described above, HEWLETT
Images were recorded using a Desk Writer C inkjet printer manufactured by PACKARD, and the following quality tests were performed. The evaluation results are shown in Table 1.

[Image section unevenness]

The image area was visually observed, and the presence or absence of unevenness particularly in the heavy color area was determined.

[Smear]

A single color or a multicolor was continuously recorded, and it was visually determined whether or not adjacent print portions bleed out to each other or to one side.

(Character drawing)

Visual determination was made as to whether or not the recorded characters were clear at high densities.

(Applicability)

When applying the ink receiving layer coating liquid, it was determined whether or not the application was difficult due to the high viscosity.

The evaluation criteria are as follows. ◎: Excellent without any problems, ○: Excellent, Δ: Usable,
X: Poor.

As is clear from the results in Table 1, the ink jet recording sheets of Examples 1 to 6 obtained good results in any of the evaluation items. On the other hand, when the molecular weight of gelatin is high as in Example 7, the compatibility with carboxymethylcellulose is poor, so that the ink receptivity is not uniform, the image area is uneven, and the character drawing performance is poor. In the case where the content of low molecular weight gelatin is small as in Example 8 or in the case where the content of mucochloric acid is large as in Example 10, the ink receiving layer is inferior in ink receptivity and the image area is remarkably blurred. When the content of the acid is small, the coating of the receiving layer is insufficiently cured, so that the receiving layer starts to flow after printing, and the character drawing property is poor. When the molecular weight of carboxymethylcellulose is high as in Example 11 or when the degree of etherification of carboxymethylcellulose is high as in Example 12, the viscosity of the coating liquid increases and the coatability deteriorates.

As described above, it is possible to obtain an ink jet recording sheet having excellent image clarity, resolution, uniformity, and ink adsorbability.

Industrial Applicability Since an excellent image can be obtained by using the ink jet recording sheet of the present invention, the recording sheet can be used in various fields such as output of a design image.

──────────────────────────────────────────────────続 き Continued on the front page (31) Priority claim number 5/157058 (32) Priority date June 28, 1993 (28 June 1993) (33) Priority claim country Japan (JP) (31) ) Priority claim number 5/158345 (32) Priority date June 29, 1993 (1993.29.29) (33) Priority claim country Japan (JP) (31) Priority claim number 5/172991 ( 32) Priority date July 13, 1993 (July 13, 1993) (33) Priority claiming country Japan (JP) (72) Inventor Yasumine Yoshida 3-4-2 Marunouchi, Chiyoda-ku, Tokyo Mitsubishi (56) References JP-A-59-222381 (JP, A) JP-A-60-248387 (JP, A) JP-A-61-32787 (JP, A) JP-A-62-218180 (JP, A) JP-A-62-263084 (JP, A) JP-A-7-195827 (JP, A) 3-114873 (JP, A) JP-A-1-146784 (JP, A) JP-A-49-115149 (JP, A) JP-A-61-181679 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B41M 5/00

Claims (4)

(57) [Claims] 1. An ink jet recording sheet having an ink receiving layer provided on a support, wherein the ink receiving layer has a molecular weight of 10
Low molecular weight gelatin having a solid content of not more than 30% by weight of the total solid content constituting the ink receiving layer, and mucochloric acid having a solid content of 0.1 to 1.0% by weight based on the gelatin content; An ink jet recording sheet comprising a component consisting of carboxymethyl cellulose having a degree of conversion of 1 or less. 2. The ink jet recording sheet according to claim 1, wherein the support is a polyolefin resin coated paper. 3. The ink jet recording sheet according to claim 1, wherein the support is a polyester film. 4. The ink jet recording sheet according to claim 2, wherein the polyolefin resin is a polyethylene resin.