JP4961676B2 - Recording paper and image forming method using the same - Google Patents

Description

    The present invention relates to a recording sheet and an electrophotographic or inkjet image forming method using the recording sheet.

  In recent years, in the field of on-demand publications, it has become easier to handle small copies, so there has been a marked movement to obtain publications that have been obtained by printing with color copiers and color printers. It has become. In order to cope with this, in the development of color copiers and color printers, higher speed and higher image quality are being promoted.

  For high image quality, the paper used for image formation has high white paper glossiness that has been used in the field of commercial printing instead of PPC paper and printer paper normally used in copying machines and the like. In many cases, coated paper is used in color copiers and color printers because of the vividness of the resulting image. In addition, the demand for the coated paper is increasing because it has high blank gloss on catalogs or booklet body papers, flyers, leaflets, etc. that are particularly required to be on-demand.

As a method of forming a color image by an electrophotographic method, an electrostatic latent image is formed for each color by irradiating the surface of a photosensitive material (latent image carrier) with color separation light, and the electrostatic latent image for each color is formed. , Y (yellow), M (magenta), C (cyan), etc., are successively developed to form a color toner image for each color, and each time the toner image is formed, the surface of the transfer member And a method of forming a color image by heating and fixing these toner images.
As another method, the color toner images of the respective colors are formed on the surface of the photosensitive material instead of the transfer body, and the superimposed color toner images are collectively transferred onto the surface of the transfer body and heated. And a method of forming a color image by fixing.

  On the other hand, the ink jet recording method has been attracting widespread attention because it is easy to colorize, has low energy consumption, low noise during recording, and can reduce the manufacturing cost of the printer. .

  In general, a copying machine or a printer supplies cut sheets to a printing unit from a tray inside the machine body or a manual feed tray installed outside the machine body. However, if high-white glossy coated paper for printing is passed in a high-temperature and high-humidity environment such as in the rainy season, there is a problem of so-called misfeed and double feed, in which the paper is in close contact and cannot be supplied.

  As a cause of misfeed or double feed of these coated papers, the present inventors usually have a coated layer that absorbs moisture compared to non-coated paper used in copying machines and printers. Therefore, in high temperature and high humidity environments, moisture on the surface of the coating layer is not easily absorbed and adheres to the surface. It was considered that the paper and the paper closely contacted to increase the coefficient of friction between the papers and hinder running.

  Up to now, as a method for improving the running property of coated paper, for example, an alkyl ketene dimer has been applied to a paper as a friction reducing agent to reduce the frictional resistance between transfer papers, thereby causing running troubles during feeding. It has been proposed to prevent (see, for example, Patent Document 1). However, this coated paper has improved running performance in abrasion, but in the environment of high temperature and high humidity, the above adhesion phenomenon has been caused and the frictional resistance between transfer papers has been greatly increased, resulting in a decrease in running performance. It seems to have done.

Furthermore, in order to improve the runnability in a high-temperature and high-humidity environment, a method of impregnating both sides of a base paper with an aqueous silicone oil-containing coating liquid having a reactive substituent has been proposed (for example, see Patent Document 2). ), The silicone oil in the base paper adheres to the roll surface of printers and copiers, which may affect the running performance, and the attached silicone oil may degrade the image quality. I don't think that was the way.
JP-A-3-220560 JP-A-4-303847

  An object of the present invention is to solve the problems of the prior art. That is, the present invention is a recording paper having a high white paper glossiness with coating layers formed on both sides of the substrate, and there is no occurrence of misfeeds or double feeds even when used in a high temperature and high humidity environment. It is an object of the present invention to provide a recording paper from which a high-quality image excellent in image contrast can be obtained, and an electrophotographic or ink jet recording image forming method using the recording paper.

The above-mentioned subject is achieved by the following present invention.
That is, the present invention
<1> A recording paper having a base material containing at least pulp fibers and a coating layer mainly composed of a pigment and an adhesive provided on both sides of the base material, the coating provided on both sides At least one of the layers contains silicone resin fine particles in a distribution state of 12 to 245 per 0.25 mm ² , the average particle size of the silicone resin fine particles is X [μm], and the coating containing the silicone resin fine particles is included. the coating thickness of the layer is taken as Y [[mu] m], the value obtained by subtracting the Y from X (X-Y) is 1 [[mu] m] or 5 [[mu] m] or less and Do Ri, white paper glossiness of 45% or more a recording paper which is characterized in der Rukoto.

< 2 > A latent image forming step of forming a latent image on the latent image carrier, a step of developing the latent image using an electrophotographic developer to form a toner image, and the developed toner image on the recording paper An electrophotographic image forming method comprising: a transfer step of transferring to a recording sheet; and a fixing step of heat-pressing the toner image transferred onto the recording sheet, wherein the recording sheet is the recording according to <1 > An image forming method characterized by being a sheet.
< 3 > An ink jet recording type image forming method for ejecting ink droplets onto a recording paper and recording an image on the surface of the recording paper, wherein the recording paper is the recording paper according to <1 >. An image forming method characterized by the above.

  According to the present invention, a recording paper having a high blank glossiness with a coating layer formed on both sides of a base material, no misfeed or double feed even when used in a high temperature and high humidity environment, and image contrast In addition, it is possible to provide a recording paper that can provide an excellent high-quality image, and an electrophotographic or ink jet recording image forming method using the recording paper.

Hereinafter, the present invention will be described in detail.
The recording paper of the present invention is a recording paper having a base material containing at least pulp fibers, and a coating layer mainly composed of a pigment and an adhesive provided on both surfaces of the base material. At least one of the coating layers provided on the surface contains organic resin fine particles in a distribution state of 12 to 245 particles per 0.25 mm ² , and the average particle diameter of the organic resin fine particles is X [μm]. When the coating thickness of the coating layer containing resin fine particles is Y [μm], the value obtained by subtracting Y from X (XY) is 1 [μm] or more and 5 [μm] or less. Is a recording sheet.

Here, the distribution state of the organic resin fine particles per 0.25 mm ² was obtained by sampling five 1 cm ² square samples from the vicinity of the center of five sheets of A4 size paper, and 0 of the organic resin fine particles in the sampled five samples. The number per 25 mm ² was measured and obtained from the average value. In the present invention, the number of organic resin fine particles was determined from a 500-fold image using a microscope (model number VH-8000) manufactured by Keyence Corporation.

  Further, the average value X of the particle diameter of the organic resin fine particles and the coating thickness Y of the coating layer were measured using a microscope (manufactured by Keyence Corporation) for a sample sampled to measure the distribution state of the organic resin fine particles. Using a model number VH-8000), a cross-sectional image of 3000 times was taken and obtained by this. The average value X of the particle diameters of the organic resin fine particles is calculated by calculating the area of 15 fine particles in the cross-sectional image, and calculating the diameter corresponding to each of the fine particles from the area of each fine particle, It calculated | required from the average value of the value. Further, the coating thickness Y of the coating layer was determined from an average value of 15 coating thicknesses measured by a cross-sectional image.

The present inventors have developed a coated paper having an image receiving surface on both sides that have been put on the market so far, a blank paper glossiness of 45% or more, and a paper basis weight of 100 g / m ² or less in a high-temperature and high-humidity environment. It was confirmed that running trouble would occur without exception when used in color copiers and printers. This is considered to be due to the surface property of the coating layer in the occurrence of misfeed and double feed in a high temperature and high humidity environment.

On the other hand, the present inventors can obtain a high-quality image with excellent image contrast and improve the runnability in a high-temperature and high-humidity environment. The relationship between the average particle diameter of the organic fine particles added to and the number of the organic resin fine particles per unit area were intensively studied. As a result, at least one of the coating layers contains organic resin fine particles in a distribution state of 12 to 245 per 0.25 mm ² , and the (XY) is set to 1 [μm] or more and 5 [μm] or less. As a result, it has been found that high-quality images with excellent image contrast can be obtained without occurrence of misfeeds and multi-feeds even when used in a high-temperature and high-humidity environment on a color copying machine or printer.
This is considered to be due to the fact that the friction coefficient between sheets is reduced without lowering the glossiness by satisfying the above-mentioned conditions. The reason why the coefficient of static friction between papers in a high-temperature and high-humidity environment can be kept low is not clear, but when the paper is shifted in the measurement of the coefficient of static friction between papers, if the lower paper is highly smooth, It is considered that the lower sheet is easy to follow, while the smoothness is lowered to suppress this follow-up and the upper sheet is likely to be displaced. In this way, the more easily the paper is displaced, the less likely it is to cause running troubles such as double feed or misfeed.

In the recording paper of the present invention, it is essential that at least one of the coating layers contains fine organic resin particles in a distribution state of 12 to 245 per 0.25 mm ² , and contains in a distribution state of 12 to 160. It is more preferable that it is contained in a distribution state of 12 to 80. When the distribution state of the organic resin fine particles is less than 12 per 0.25 mm ² in at least one of the coating layers, the frictional resistance between the sheets under high temperature and high humidity increases, and troubles such as double feeding occur. Resulting in. On the other hand, if the number exceeds 245, the glossiness decreases and a high-quality image with excellent image contrast cannot be obtained.

  In the recording paper of the present invention, it is essential that the (XY) is 1 [μm] or more and 5 [μm] or less, and preferably 2 [μm] or more and 4 [μm] or less. It is more preferable that it is [μm] or more and 4 [μm] or less. If the (XY) is less than 1 [μm], the frictional resistance between the sheets under high temperature and high humidity increases, and a running trouble such as double feeding occurs. On the other hand, if it exceeds 5 [μm], the glossiness is lowered and a high-quality image excellent in image contrast cannot be obtained.

The recording paper of the present invention is preferable because the effect of the present invention is more exerted when the glossiness of blank paper, which frequently causes troubles, is 45% or more and the basis weight of the paper is 100 g / m ² or less.
For this reason, the recording paper of the present invention preferably has a blank paper glossiness of 45% or more. If the white paper glossiness is less than 45%, the image formed on the paper surface may not be sharp. Further, the glossiness of the white paper is more preferably in the range of 45 to 80%, and further preferably in the range of 50 to 75% from the viewpoint of harmony with the toner image portion glossiness. The glossiness of the white paper can also be adjusted by changing the number of organic resin fine particles. Specifically, the glossiness of blank paper can be increased by reducing the number of organic resin fine particles per 0.25 mm ² .
In the present invention, the white paper glossiness was measured at an incident angle of 75 ° in accordance with JIS P-8124.

The recording paper of the invention, in that the effect of the present invention are exhibited more, preferably the basis weight of the sheet is 100 g / m ² or less, the basis weight of the paper is 40 to 100 g / m ² range It is more preferable that If the basis weight of the paper is less than 40 g / m ² , the paper may become too small and the paper may not be peeled off due to the suction between the paper and the member in the transfer area or the fixing area. On the other hand, if the basis weight exceeds 100 g / m ² , a texture equivalent to that of a light-weight coated paper used for a normal catalog or booklet body paper, leaflet, or leaflet may not be obtained.
It is preferable that the basis weight of the recording paper is a coated paper in the range of 60 to 85 g / m ² that is often used for the above-mentioned catalog or booklet text paper, leaflet, leaflet. it is preferable that the basis weight of the paper is made to design a range of 60~85g / m ^2. The basis weight of the paper was measured according to JIS P-8124.

  In addition, the recording paper of the present invention has a texture similar to that of a conventional coated paper such as a catalog and reduces the manufacturing cost. It is necessary to have a coating. Here, “consisting mainly of pigment and adhesive” means that the total content of pigment and adhesive is 5% by mass or more.

Furthermore, the density of the recording paper of the present invention is preferably adjusted to be in the range of 0.90 to 1.50 g / cm ³ . If the density of the sheet is more than 0.90 g / cm ³ less than, or 1.50 g / cm ^3, greater paper thickness of the paper, usually, catalog or booklet text sheets, flyers, a coated paper for use in the leaflet Because they are different, the tactile sensation when they are held may change significantly. The density of the sheet, more preferably in the range of 1.00~1.40g / cm ^3, more preferably in the range of 1.10~1.35g / cm ^3. The density and thickness of the paper in the present invention are measured according to JIS P-8118.

  The substrate of the recording paper of the present invention is not particularly limited as long as it contains at least pulp fibers, but synthetic resin films and sheets, or various fiber sheets are used. The fiber used is not particularly limited, but pulp fibers used for the base paper (base material) of ordinary general coated paper, such as sulfite pulp fibers, kraft pulp fibers, semi-chemical pulp fibers, In addition to chemiground pulp fiber, groundwood pulp fiber, refiner ground pulp fiber, thermomechanical pulp fiber, etc., cotton pulp fiber, hemp pulp fiber, kenaf pulp fiber are included, and these pulp fibers are vulcanized fiber, viscose rayon fiber, copper ammonia. Rayon fiber, cellulose acetate fiber, polyamide fiber, polyester fiber, polyacrylonitrile fiber, polyvinyl alcohol fiber, polyvinyl chloride fiber, polyvinylidene chloride fiber, polyolefin fiber, polyurethane fiber, polyvinyl chloride, Li vinyl alcohol copolymer, polyalkylene para oxybenzoate fibers, fluorocarbon fibers, glass fibers, can be used carbon fibers, alumina fibers, metal fibers, silicon carbide fibers, etc. alone or in combination.

  Moreover, if necessary, fibers obtained by impregnating or heat-sealing synthetic resins such as polyethylene, polypropylene, polystyrene, polyvinyl chloride, and polyester into the pulp fibers can also be used. Furthermore, the sheet itself made using the pulp fiber or the like can be impregnated with a synthetic resin.

  In consideration of recent environmental problems, it is desirable to add high-quality and medium-quality waste paper pulp to the base material in the present invention, and its blending amount is determined according to the use, but it is 30 mass in all fibers. % Or more, preferably 50% by mass or more, and more preferably 70% by mass or more.

  Furthermore, it is preferable to use a filler for the base material in the present invention in order to improve the coating suitability and to adjust the opacity and whiteness after coating. Fillers that can be used here include kaolin, heavy calcium carbonate, light calcium carbonate, calcined clay, silicic acids such as pyroferrite, sericite, and talc, inorganic fillers such as titanium dioxide, and organic resins such as urea resins and polystyrene. Although resin can be mentioned, it is not limited to these. Although the compounding quantity of these fillers is not specifically limited, It is preferable that it is the range of 1-20 mass%, and it is more preferable that it is the range of 3-15 mass%.

  On the other hand, various chemicals such as a sizing agent used for the base material used in the present invention can be used by internal or external addition. Examples of the sizing agent include sizing agents such as rosin sizing agents, synthetic sizing agents, petroleum resin sizing agents, and neutral sizing agents, and suitable sizing agents and fibers such as sulfate bands and cationized starches. Can also be used in combination with a fixing agent. From the viewpoint of paper storage stability after copying in electrophotographic copying machines, printers, etc., neutral sizing agents such as alkenyl succinic anhydride sizing agents, alkyl ketene dimers, alkenyl ketene dimers, neutral rosins, petroleum sizes, Olefin resins and styrene-acrylic resins are preferred.

  Furthermore, for the purpose of adjusting the electrical resistance of paper, inorganic substances such as sodium chloride, potassium chloride, calcium chloride, sodium sulfate, zinc oxide, titanium dioxide, tin oxide, aluminum oxide, magnesium oxide, alkyl phosphate esters, alkyl Organic materials such as sulfuric ester acid, sulfonic acid sodium salt, quaternary ammonium salt and the like can be used alone or in combination.

In this case, the volume resistivity of the paper is preferably in the range of 1 × 10 ⁹ to 1 × 10 ¹⁴ Ω · cm, and more preferably in the range of 1 × 10 ¹⁰ to 1 × 10 ¹² Ω · cm. .
In addition, the volume resistivity mentioned here uses a resistivity meter and a resistance measurement chamber (trade names: R8340 and R12704, manufactured by Advantest), and in an environment of 23 ° C. and 50% RH according to JIS K-6911. It was measured under the conditions of an applied voltage of 100 V and an electrode of 50 mmφ.

Further, a paper strength enhancer can be internally or externally added to the substrate in the present invention.
Examples of the paper strength enhancer include starch, modified starch, vegetable gum, polyvinyl alcohol, carboxymethylcellulose, polyacrylamide, urea-formaldehyde resin, melamine-formaldehyde resin, dialdehyde starch, polyethyleneimine, epoxidized polyamide, polyamide-epichlorohydrin. Resin, methylolated polyamide, chitosan derivative and the like, and these materials can be used alone or in combination. In addition to these, various auxiliaries such as dyes, pH adjusters and the like blended in ordinary coated paper base materials are appropriately used.

Next, the coating layer in the recording paper of the present invention will be described.
The organic resin fine particles contained in the coating layer in the present invention are not particularly limited as long as the above-mentioned (XY) is 1 [μm] or more and 5 [μm] or less. Silicone resin fine particles, fluorine Examples thereof include resin fine particles, acrylic resin fine particles, benzoguanamine resin fine particles, and polyethylene resin fine particles. Among these resin fine particles, silicone resin fine particles are preferable from the viewpoint of slipperiness. Further, in consideration of the fixing process of the electrophotographic system, it is preferable to have heat resistance, and the softening point is preferably 200 ° C. or more of the temperature of the electrophotographic fixing apparatus generally used.

Further, the particle diameter of the organic resin fine particles is not particularly limited as long as the above-described (XY) is 1 [μm] or more and 5 [μm] or less. Depending on the coating thickness, 4 to 20 μm is preferable, and 4 to 12 μm is more preferable.
On the other hand, the shape of the organic resin fine particles may be any of spherical, needle-like, flake-like, cubic, columnar, indefinite, etc., but the shape has a great influence on the characteristics, and the thickness of the coating layer and the slip It is desired to select it in consideration of the property and glossiness, and it is preferably spherical and more preferably spherical and transparent.

  The addition amount of the organic resin fine particles is affected by the feeding method of the recording paper of the present invention in the electrophotographic apparatus, environmental conditions, etc., and considering the influence on the glossiness of the white paper, it is 0. It is preferably 5 to 3% by mass, and more preferably 0.5 to 2% by mass.

  As the pigment contained in the coating layer in the present invention, pigments used in ordinary general coated paper, for example, heavy calcium carbonate, light calcium carbonate, titanium dioxide, aluminum hydroxide, satin white, talc, calcium sulfate, Mineral pigments such as barium sulfate, zinc oxide, magnesium oxide, magnesium carbonate, amorphous silica, colloidal silica, white carbon, kaolin, calcined kaolin, delaminated clay, aluminosilicate, sericite, bentonite, smectite, Polystyrene resin fine particles, urea formaldehyde resin fine particles, fine hollow particles, and other organic pigments can be used alone or in combination.

  Various adhesives such as styrene-butadiene, styrene-acryl, ethylene-vinyl acetate, butadiene-methyl methacrylate, and vinyl acetate-butyl acrylate are used as the adhesive used for the coating layer in the present invention; polyvinyl Synthetic adhesives such as alcohol, maleic anhydride copolymer, acrylic acid-methyl methacrylate copolymer: oxidized starch, esterified starch, enzyme-modified starch, cold water soluble starch obtained by flash drying them, casein, Examples include generally known adhesives such as natural adhesives such as soybean protein.

The amount of the adhesive used is preferably 5 to 50 parts by mass and more preferably 10 to 30 parts by mass per 100 parts by mass of the pigment.
Further, in the coating layer in the present invention, various auxiliary agents blended in ordinary coating pigments such as a dispersant, a thickener, a water retention agent, an antifoaming agent, a water-resistant agent and the like are appropriately included as necessary. used.

  In the present invention, the formation of the coating layer is highly glossy, but in order to suppress smoothness, a pigment that is easy to orient the pigment during the smoothing process using a calendar, for example, the organic pigment, columnar calcium carbonate, columnar It is preferable to use a pigment such as kaolin.

  The coating layer in the present invention preferably contains 5 parts by mass or more, more preferably 15 parts by mass or more of the organic pigment or columnar calcium carbonate or kaolin pigment in 100 parts by mass of the pigment. More preferably, 25 parts by mass or more is blended. The organic pigments or columnar calcium carbonate or kaolin pigments may be used alone or in combination.

  As the adhesive, among the synthetic adhesives, those having a high glass transition temperature, such as those having a styrene monomer compounding ratio of 65% or more in the case of styrene-butadiene, or styrene-acrylic, vinyl acetate It is preferable to use a butyl acrylate system or the like. The glass transition temperature is preferably 10 ° C. or higher, more preferably 20 ° C. or higher, and further preferably 30 ° C. or higher.

  The coating composition for forming the coating layer prepared as described above is used as a coating apparatus used in general coated paper production, such as a blade coater, an air knife coater, a roll coater, a reverse roll coater, and a bar coater. A curtain coater, a die slot coater, a gravure coater or the like is preferably used to coat the substrate surface in one layer or multiple layers by on-machine or off-machine.

The coating layer is preferably applied so as to be in a range of 5 to 50 g / m ^{2 on} one side by dry mass, and more preferably in a range of 10 to 25 g / m ^2. preferable.

  For the smoothing treatment after coating of the coating layer, a smoothing apparatus usually used, for example, a super calender, a machine calender, a soft nip calender, or the like is used and finished so that the glossiness of blank paper is 45% or more. It is preferable.

  Further, in order to give a stable feeding property to the paper, it is preferable to finish the paper so that the inter-sheet static friction coefficient is in the range of 0.5 to 0.9, and the finish is in the range of 0.5 to 0.75. It is more preferable. The measurement environment of the inter-sheet static friction coefficient of the paper is 10 ° C., 15% RH, 23 ° C., 50% RH, 28 ° C., 85% RH.

<Image recording method>
Next, the image recording method of the present invention will be described.
The image recording method of the present invention can be applied to recording using an inkjet ink (hereinafter sometimes abbreviated as “ink”) or an electrophotographic toner (hereinafter sometimes abbreviated as “toner”). The recording paper is not particularly limited as long as the recording paper is used.
The electrophotographic image forming method of the present invention for recording using toner comprises a latent image forming step of forming a latent image on a latent image carrier, and developing the latent image with an electrophotographic developer to form a toner image. An electrophotographic image forming method comprising: a step of forming a toner image; a transfer step of transferring the developed toner image onto a recording paper; and a fixing step of heat-pressing the toner image transferred onto the recording paper. The recording paper is the recording paper of the present invention described above.

Hereinafter, the electrophotographic image forming method of the present invention will be described in detail.
FIG. 1 is a schematic configuration diagram showing an example of an image forming apparatus preferably used in the image forming method of the present invention. The image forming apparatus shown in FIG. 1 includes a photoconductor 11, and around the photoconductor 11, a roller-type charger 12, an exposure device 13, and a developer 14a that incorporates cyan, magenta, yellow, and black developers. , 14b, 14c, and 14d, the belt-like intermediate transfer member 15, the cleaner 16, and the light static eliminator 17 are arranged in this order. The intermediate transfer member 15 is stretched by support shaft rollers 18a, 18b, and 18c. The support roller 18 a is in pressure contact with the photoreceptor 11 via the intermediate transfer member 15. The support roller 18 c is in pressure contact with the transfer roller 19 via the intermediate transfer member 15. Further, a heat roll fixing device including a heating roller 1 and a pressure roller 2 for fixing the toner image 6 transferred to the transfer target 7 by the transfer roll 19 is provided.

  An image is formed as follows using the image forming apparatus shown in FIG. The surface of the photoconductor (latent image carrier) 11 charged by the charger 12 is exposed by the exposure device 13 based on each image information of cyan, magenta, and yellow to form a latent image on the surface of the photoconductor 11. The latent image on the surface of the photoconductor 11 is developed by the developing devices 14a, 14b, 14c, and 14d incorporated in the developing device 14, and a toner image is formed. The developed toner image is transferred to the surface of the belt-shaped intermediate transfer member 15. The toner image on the surface of the intermediate transfer body 15 moves between the support roller 18c and the transfer roller 19 that is in pressure contact with the intermediate transfer body 15 as the intermediate transfer body 15 advances in the direction of arrow P. . When the toner image on the surface of the intermediate transfer member 15 passes between the support roller 18c and the transfer roller 19 that is in pressure contact with the intermediate transfer member 15 (nip portion), the toner image inserted through the nip portion is passed through. Transferred to the surface of the transfer body 7. The toner image transferred onto the surface of the transfer body 7 is fixed on the surface of the transfer body 7 by passing the transfer body 7 between the heating roller 1 and the pressure roller 2 to form an image. After the toner image on the surface of the photoconductor 11 is transferred to the transfer target 20, the toner image remaining on the surface of the photoconductor 11 is removed by the cleaner 16, and the residual charge remaining on the surface of the photoconductor 11 is removed by the photocharger 17. The charge is removed, and the next image formation is prepared.

  In the above-described electrophotographic image formation, if the recording paper of the present invention is used as the transfer target 7, not only single-sided printing but also double-sided printing can produce a good image with almost no running trouble. Obtainable.

Next, an image forming method of the present invention using an ink jet method for recording using ink will be described. The image forming method of the present invention of an ink jet system is an image forming method of an ink jet recording system in which ink droplets are ejected onto a recording paper and an image is recorded on the surface of the recording paper. The recording paper of the present invention is used.
The ink used in the image forming method of the present invention of the ink jet system is not particularly limited as long as it is a known ink, but an ink containing water and a color material is preferable.

  Here, in addition to the dye, the coloring material includes not only a hydrophobic pigment which is used in combination with a pigment dispersant containing a hydrophilic group and thereby can be dispersed in the ink, but also a self-dispersing pigment described later. In addition to water, a known water-soluble organic solvent can be used as the solvent, and various additives such as a surfactant can be further contained as required.

  When printing on the recording paper of the present invention by the ink jet method, the amount of ink drop ejected from the nozzle is preferably in the range of 1 to 20 pl, and more preferably in the range of 3 to 18 pl.

  The ink jet image forming method of the present invention can obtain good print quality even if any ink jet recording method is used as long as it is a known ink jet device. Furthermore, for a system having a function of promoting the absorption and fixing of ink by providing heating means such as recording paper during printing or before and after printing, and heating the recording paper and ink at a temperature of 50 ° C. to 200 ° C. Also, the ink jet recording method of the present invention can be applied.

  As a method for ejecting ink from a nozzle, there is a so-called thermal ink jet method in which ink in a nozzle is foamed by energizing and heating a heater provided in the nozzle, and the ink is ejected by the pressure. There is also a method in which a piezoelectric element is electrically deformed to physically deform the element, and ink is ejected from the nozzles using a force generated by the deformation. In this system, a piezoelectric element using a piezo element is typical. In the ink jet recording apparatus used in the ink jet recording method of the present invention, the method for ejecting ink from the nozzles may be any of the above methods, and is not limited to these methods.

  In the above-described ink jet image forming method of the present invention, if the recording paper of the present invention is used as the recording paper, a good image can be obtained with almost no running trouble.

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated more concretely, this invention is not limited by this. In the examples and comparative examples, “part” means “part by mass” and “%” means “% by mass” unless otherwise specified.

Example 1
<Preparation of recording paper>
A pulp slurry of 20 parts of LBKP (freeness (CSF) = 500 ml) and 80 parts of NBKP (freeness (CSF) = 500 ml) and a polyacrylamide resin (trade name: PS3874-20, Arakawa Chemical Industries, Ltd.) as a paper strength enhancer. 2.5%) was added, and these mixtures were diluted with white water to prepare a paper slurry having a pH value of 5.6 and a solid content concentration of 0.3%.

Paper stock slurry is made using an oriented sheet former (manufactured by Kumagai Rikyu Kogyo Co., Ltd.). Oxidized starch (trade name: Ace C, manufactured by Oji Constarch Co., Ltd.) is applied to this wet paper. It is applied with a size press so that the dry mass becomes 2.5 g / m ^2, and after drying, it is subjected to a fairly strong smoothing treatment with a machine calendar so that the Oken type smoothness becomes 70 seconds. Of 55 g / m ² was obtained.

  Next, it consists of 25 parts of columnar light calcium carbonate (trade name: TP-123CS, manufactured by Okutama Kogyo Co., Ltd.) and 75 parts of kaolin (trade name: Ultra White 90, manufactured by Engelhard Co., Ltd.). For 100 parts of pigment component, 3 parts of oxidized starch (trade name: Ace A, manufactured by Oji Cornstarch Co., Ltd.) (solid ratio to pigment: the same applies below) and synthetic adhesive (trade name: Nipol LX430, Nippon Zeon) 10 parts of Co., Ltd. and 0.3 parts of a dispersant (trade name: Aron T-40, manufactured by Toa Gosei Co., Ltd.) were blended. Further, 0.5 parts of heat-resistant silicone resin fine particles (trade name: Tospearl, manufactured by Nissho Sangyo Co., Ltd., particle size 11 μm) were added to obtain a coating composition 1.

The coating composition 1 was coated on the surface of the base paper 1 with a blade coater so that the coating amount on one side was 12.5 g / m ² , dried, and then a super calender with a roll temperature of 50 ° C. Then, a recording paper 1 having a basis weight of 80 g / m ² having a coating layer formed on both sides was prepared by smoothing the paper surface. The coating thickness of the coating layer of the recording paper 1 was measured by the method described above and found to be 8.4 [μm].

<Evaluation of recording paper>
The recording paper 1 was evaluated as follows.
−Evaluation of basis weight, white paper gloss, paper thickness / density, smoothness−
The basis weight was measured according to the method of JIS P-8124, and the blank paper glossiness was measured at an incident angle of 75 degrees according to JIS P-8142. The thickness and density of the paper were measured according to the method of JIS P-8118. The smoothness of the paper was measured according to the method of Oken type smoothness (JAPN TAPPI No. 5). The values are shown in Table 1.

-Measurement of static friction coefficient between paper-
The measurement of the inter-sheet static friction coefficient of the recording paper 1 and its change is described in J. TAPPINo. According to 30, it measured as follows. About 30 sheets of A4-sized recording paper 1 immediately after unpacking was collected and used as a test piece in the state of being laminated at the time of opening. However, in order to remove other factors, the measurement was performed after the paper was once struck in advance and the air existing between the papers was removed. The weight for measurement was 240 g in weight, 63 mm in width, and 75 mm in length. Measurement is performed continuously in the vertical direction of the paper in three environments of 10 ° C, 15% RH (low temperature and low humidity environment), 23 ° C, 50% RH, 28 ° C, 85% RH (high temperature and high humidity environment). It was. The values are shown in Table 1. The moving speed of the weight was 150 mm / min.

(Evaluation with electrophotographic image forming method)
-Actual machine running test-
The running test of the recording paper 1 was carried out using a dry indirect electrophotographic digital color copying machine DocuCenterColor500CP manufactured by Fuji Xerox Co., Ltd. The recording paper 1 was A4 size vertical paper, and 100 sheets were run with the short side as the leading edge. The total number of misfeeds, paper jams and double feeds in a high temperature and high humidity environment was counted as the number of running troubles. The evaluation criteria were as follows. The results are shown in Table 1.
A: Misfeed, paper jam, and double feed do not occur at all.
○: Misfeed, paper jam, and double feed occur slightly, but there is no practical problem.
X: Misfeeds, paper jams, and multiple feeds frequently occur.
XX: Cannot run due to misfeed, paper jam, or double feed.

-Image contrast evaluation-
Using the digital color copying machine DocuCenterColor500CP, an image identification number N1 (image name: portrait) of an ISO / JIS-SCID sample (issued by the Japanese Standards Association) is output, and the following evaluation criteria for the image contrast of the recording paper 1 It was evaluated with. The results are shown in Table 1.
A: Excellent with no difference between the glossiness of the image area and the glossiness of the white paper.
○: Good with little difference between glossiness of image area and glossiness of blank paper.
Δ: The difference between the glossiness of the image area and the glossiness of the white paper is slightly inferior.
X: The difference between the glossiness of the image area and the glossiness of the white paper is large and extremely inferior.

(Example 2)
A pulp slurry of 80 parts of LBKP (freeness (CSF) = 200 ml) and 20 parts of NBKP (freeness (CSF) = 400 ml) and a polyacrylamide resin (trade name: PS3874-20, Arakawa Chemical Industries, Ltd.) as a paper strength enhancer. 1.7%) was added, and these mixtures were diluted with white water to prepare a paper slurry having a pH value of 5.4 and a solid content concentration of 0.5%.

This stock slurry is made using an oriented sheet former (manufactured by Kumagai Rikyu Kogyo Co., Ltd.), and then this wet paper is coated with polyvinyl alcohol (trade name: Kuraray Poval PVA-117, Kuraray Co., Ltd.). Is applied with a size press so that the coating amount is 3.0 g / m ² in terms of dry mass, and after drying, a smoothing treatment is performed by a machine calendar so that the Oken smoothness becomes 70 seconds. subjecting a basis weight to obtain a base paper (base material) ² 55g / m 2.

Next, a coating composition was obtained in the same manner as in Example 1 except that the silicone resin fine particles having a particle diameter of 11 μm were changed to silicone resin fine particles having a particle diameter of 13 μm (trade name: Tospearl, manufactured by Nissho Sangyo Co., Ltd.). Product 2 was obtained.
Further, in the same manner as in Example 1, the coating liquid 2 was applied to the surface of the base paper 2 and smoothed to prepare a recording paper 2 having a basis weight of 80 g / m ² . The produced recording paper 2 was evaluated in the same manner as in Example 1. The results are shown in Table 1.

(Example 3)
Column-shaped light calcium carbonate (trade name: TP-123CS, manufactured by Okutama Kogyo Co., Ltd.), 30 parts, kaolin (trade name: Ultra White 90, manufactured by Engelhard Co., Ltd.), and styrene-acrylic 3 parts of oxidized starch (trade name: Ace A, manufactured by Oji Cornstarch Co., Ltd.) as an adhesive for 100 parts of pigment component comprising 30 parts of organic pigment (trade name: Nipol MH5055, manufactured by Nippon Zeon Co., Ltd.) (Solid ratio to pigment) and synthetic adhesive (trade name: Nipol LX430, manufactured by Nippon Zeon Co., Ltd.), 11 parts, dispersant (trade name: Aron T-40, manufactured by Toa Gosei Co., Ltd.) 0.3 1 part of a silicone resin fine particle (trade name: Tospearl, manufactured by Nissho Sangyo Co., Ltd.) was added to obtain 1 part of coating composition 3.

The coating composition 3 was coated on the surface of the substrate 2 by the same method as in Example 2 using a blade coater so that the coating amount on one side was 12.5 g / m ^2, and after drying, The paper surface was smoothed by a super calender with a roll temperature of 50 ° C. to prepare a recording paper 3 having a basis weight of 80 g / m ² . The produced recording paper 3 was evaluated in the same manner as in Example 1. The results are shown in Table 1.

Example 4
A pulp slurry of 20 parts of LBKP (freeness (CSF) = 150 ml) and 80 parts of NBKP (freeness (CSF) = 500 ml) and a polyacrylamide resin (trade name: PS3874-20, Arakawa Chemical Industries, Ltd.) as a paper strength enhancer. 5.0%) was added, and these mixtures were diluted with white water to prepare a paper slurry having a pH value of 5.8 and a solid content concentration of 0.05%.

This stock slurry is made using an oriented sheet former (manufactured by Kumagai Rikyu Kogyo Co., Ltd.), and then oxidized starch (trade name: Ace C, manufactured by Oji Constarch Co., Ltd.) is applied to the wet paper. Apply with a size press device so that the amount is 2.5 g / m ² in dry mass, and after drying, apply a strong smoothing treatment with a machine calendar so that the Oken smoothness becomes 30 seconds, A base paper (base material) 4 having a basis weight of 55 g / m ² was obtained.

  Next, 35 parts of columnar light calcium carbonate (trade name: TP-123CS, manufactured by Okutama Kogyo Co., Ltd.), and 35 parts of kaolin (trade name: Ultra White 90, manufactured by Engelhard Co., Ltd.) Oxidized starch (trade name: Ace A, manufactured by Oji Cornstarch Co., Ltd.) as an adhesive for 100 parts of pigment component comprising 30 parts of styrene-acrylic organic pigment (trade name: Nipol MH5055, manufactured by Nippon Zeon Co., Ltd.) ) 3 parts (solid ratio to pigment) and synthetic adhesive (trade name: Nipol LX430, manufactured by Nippon Zeon Co., Ltd.), dispersant (trade name: Aron T-40, manufactured by Toa Gosei Co., Ltd.) 0.3 parts was blended, and further silicone resin fine particles (trade name: Tospearl, manufactured by Nissho Sangyo Co., Ltd.) with a particle size of 8 μm were added to obtain a coating composition 4.

The coating composition 4 is coated on the surface of the substrate 4 with a blade coater so that the coating amount on one side is 10 g / m ^2, and after drying, with a super calender at a roll temperature of 50 ° C., The paper surface was smoothed to prepare a recording paper 4 having a basis weight of 75 g / m ² . The produced recording paper 4 was evaluated in the same manner as in Example 1. The results are shown in Table 1.

(Comparative Example 1)
In the production of the coating composition 1 in Example 1, the recording paper 5 was produced in the same manner as in Example 1 except that the silicone organic resin fine particles were not added, and the same evaluation as in Example 1 was performed. The results are shown in Table 1.

(Comparative Example 2)
In the production of the coating composition 2 in Example 2, the recording paper 6 was produced in the same manner as in Example 2 except that the silicone organic resin fine particles having a particle size of 13 μm were changed to the silicone organic resin fine particles having a particle size of 14 μm. Evaluation similar to Example 1 was performed. The results are shown in Table 1.

(Comparative Example 3)
In the production of the coating composition 3 in Example 3, the recording paper 7 was produced in the same manner as in Example 3 except that the silicone organic resin fine particles having a particle size of 10 μm were changed to the silicone organic resin fine particles having a particle size of 9 μm. Evaluation similar to Example 1 was performed. The results are shown in Table 1.

(Comparative Example 4)
In the production of the coating composition 4 in Example 4, a recording paper 8 was produced in the same manner as in Example 4 except that the addition amount of the silicone organic resin fine particles having a particle diameter of 8 μm was changed to 2.5 parts. Evaluation similar to 1 was performed. The results are shown in Table 1.

Next, an embodiment using an ink jet system will be described.
(Example 5)
<Preparation of recording paper>
The surface of the substrate 2 contains 70% of synthetic amorphous silica fine particles (Mizukasil P-78D having a BET specific surface area of 300 m ² / g: manufactured by Mizusawa Chemical Industry Co., Ltd.), and as a binder, completely saponified polyvinyl alcohol (PVA117: 25 parts of Kuraray Co., Ltd., 5 parts of water-based cationic polymer (Evomin P1000: made by Nippon Shokubai Co., Ltd.) as a waterproofing agent, and silicone resin fine particles (trade name: Tospearl, manufactured by Nissho Sangyo Co., Ltd.) , Particle size 13 μm) 0.5 part was added to obtain a coating composition 5.

The coating composition 5 was coated on the surface of the base paper 2 with a blade coater so that the coating amount on one side was 12.5 g / m ² , dried, and then a super calendar having a roll temperature of 50 ° C. Then, a recording paper 9 having a basis weight of 80 g / m ² having a coating layer formed on both sides was prepared by smoothing the paper surface.

(Evaluation by inkjet image forming method)
-Actual machine running test-
The running test of the recording paper 9 was performed using a printer IPSiO G707 manufactured by Ricoh. The recording paper 1 was A4 size vertical paper, and was run 100 sheets each with the short side as the leading edge. The total number of misfeeds, paper jams and double feeds in a high temperature and high humidity environment was counted as the number of running troubles. The evaluation criteria were as follows. The results are shown in Table 2.
A: Misfeed, paper jam, and double feed do not occur at all.
○: Misfeed, paper jam, and double feed occur slightly, but there is no practical problem.
X: Misfeeds, paper jams, and multiple feeds frequently occur.
XX: Cannot run due to misfeed, paper jam, or double feed.

-Image contrast evaluation-
An image identification number N1 (image name: portrait) of an ISO / JIS-SCID sample (issued by the Japanese Standards Association) was output using a printer IPSiO G707 manufactured by Ricoh, and the image contrast was evaluated according to the following evaluation criteria. The results are shown in Table 2.
A: Excellent with no difference between the glossiness of the image area and the glossiness of the white paper.
○: Good with little difference between glossiness of image area and glossiness of blank paper.
Δ: The difference between the glossiness of the image area and the glossiness of the white paper is slightly inferior.
X: The difference between the glossiness of the image area and the glossiness of the white paper is large and extremely inferior.

(Comparative Example 5)
A recording paper 10 was produced in the same manner as in Example 5 except that the particle size of the silicone organic resin fine particles having a particle size of 13 μm was changed to 14 μm in the production of the coating composition 5 in Example 5. Was evaluated. The results are shown in Table 2.

  As is apparent from the results shown in Tables 1 and 2, the recording papers of the present invention of Examples 1 to 4 have no running trouble under high temperature and high humidity, and have a good image portion contrast. On the other hand, the recording papers of Comparative Examples 1, 2, 3, and 5 are at a level that causes running troubles in a high-temperature and high-humidity environment and cannot withstand practical use as recording paper. Further, the recording sheets of Comparative Examples 3 and 4 are greatly inferior in terms of image portion contrast.

  Therefore, the recording paper of the present invention has excellent running performance in an electrophotographic copying machine or printer, and can achieve high image quality, compared to conventional coated paper. The product value is extremely large.

1 is a schematic configuration diagram illustrating an example of an image output apparatus used in an image forming method of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Thermal fixing roller 2 Pressure roller 3 Heat source 4 Fixing member surface layer 5 Elastic layer 6 Toner image 7 Transfer object 11 Photoconductor (latent image carrier)
12 roller type charger 13 exposure device 14 developing device (14a, 14b, 14c, 14d)
15 Intermediate transfer member 16 Cleaner 17 Optical static eliminators 18a, 18b, 18c Support roller 19 Transfer roller

Claims (3)

A recording paper having a base material containing at least pulp fibers and a coating layer mainly composed of a pigment and an adhesive provided on both surfaces of the base material,
At least one of the coating layers provided on both surfaces contains silicone resin fine particles in a distribution state of 12 to 245 per 0.25 mm ² , and the average value of the particle sizes of the silicone resin fine particles is X [μm], the coating thickness of the coated layer containing the silicone resin fine particles is taken as Y [[mu] m], the value obtained by subtracting the Y from X (X-Y) Ri is Do the 1 [[mu] m] or 5 [[mu] m] or less ,
Recording paper white paper glossiness is characterized der Rukoto 45% or more. A latent image forming step of forming a latent image on the latent image carrier, a step of developing the latent image using an electrophotographic developer to form a toner image, and transferring the developed toner image onto a recording sheet An electrophotographic image forming method comprising: a transfer step; and a fixing step of heat-pressing the toner image transferred onto the recording paper,
The image forming method according to claim 1, wherein the recording sheet is the recording sheet according to claim 1 . An ink jet recording image forming method for discharging ink droplets onto a recording paper and recording an image on the surface of the recording paper,
The image forming method according to claim 1, wherein the recording sheet is the recording sheet according to claim 1 .

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