JP5663987B2 - Inkjet recording paper - Google Patents

Description

  The present invention relates to an ink jet recording paper containing recycled pulp, and more particularly to an ink jet recording paper suitable for a postcard paper for ink jet recording.

In general, paper is roughly classified into paper and paperboard. There are various uses of the former paper, and postcards called “public postcards” (or “postcards”) and “private postcards” are one of them. A postcard is usually a postcard paper made from raw pulp and cut into a predetermined size. In the case of a government-made postcard, a postage stamp face with a face value that has the same effect as a postal code box or stamp is printed on the surface. Printed. New year's cards with New Year's cards and summer letter postcards are printed with a group number and lottery number at the bottom. These printings are usually performed by an offset printing method.
As such a postcard paper, for example, Patent Document 1 (Japanese Patent No. 3755483) describes that chemical pulp, deinked pulp, or the like is mixed and calcium carbonate is used as a filler. Patent Document 2 (Japanese Patent Application Laid-Open No. 2004-100049) describes that an ink receiving layer is provided on one surface of a multi-layer support so as to be suitable for ink jet recording. Patent Document 3 (Japanese Patent Laid-Open No. 2003-291515), Patent Document 4 (Japanese Patent Laid-Open No. 2002-127492), Patent Document 5 (Japanese Patent Laid-Open No. 10-297148), and Patent Document 6 (Japanese Patent No. 4031277) Describes that it is excellent in ink absorbability as a support having a multilayer structure of two or more layers.

  In recent years, in the manufacture of paper, the use of waste paper as a raw material pulp has been promoted with an increase in environmental awareness such as recycling and resource saving. There is a very high demand for the use of used paper even for postcard paper and sealed paper. For example, Patent Document 7 (Japanese Patent Laid-Open No. 2005-35224) describes a transportation system for postcards containing recycled pulp obtained from waste paper as raw pulp.

  On the other hand, the post office can read the postal code and address name written by the sender in the postal item with OCR, print the destination information as a bar code, and sort and convey it by machine processing with an automatic sorter. Has been done. The bar code is printed as invisible information that cannot be seen by the eyes using infrared or ultraviolet excited fluorescent stealth ink. For example, Patent Document 8 (Japanese Patent Laid-Open No. 11-076950) describes a barcode printing system for sorting mail items. Patent Document 9 describes a recycled postcard paper that is made by multi-layered stitching of three or more layers containing 40% by weight or more of waste paper pulp.

Japanese Patent No. 3755483 JP 2004-100049 A JP 2003-291515 A JP 2002-127582 A JP-A-10-297148 Patent No. 4031277 JP 2005-035224 A Japanese Patent Application Laid-Open No. 11-076950 JP 2010-047894 A

  As described above, the mail is a system that is efficiently transported by optically reading the destination information described by the sender and converting it into a stealth bar code. However, in the manufacture of paper, dust, pitch, and other contaminants such as ink and toner derived from waste paper are likely to enter the pulp. There is a problem that the accuracy is lowered and the barcode is not accurately generated. In addition, fluorescent materials such as fluorescent dyes contained in waste paper reduce the contrast between the barcode printing area and the ground color area, hinder barcode reading with an automatic sorting machine, and are not transported correctly. There is. When a large amount of recycled pulp made from waste paper is blended, the reading accuracy of the destination information and the stealth barcode described by the sender is further deteriorated. In addition, when the recycled pulp is highly blended, there is a problem that the appearance of the product such as whiteness is also impaired.

  As described above, the promotion of waste paper use and the efficiency of the postal transport system are inversely proportional, and it is desired to increase the number of recycled pulp without deteriorating the reading accuracy of destination information and barcode. SUMMARY OF THE INVENTION An object of the present invention is to provide an ink jet recording paper suitable for a postcard paper for ink jet recording having excellent whiteness, low fluorescence intensity, and less dust and dirt while containing a high proportion of recycled pulp.

  The inventors of the present invention have solved the above problems by using a pulp having a high whiteness among recycled pulps, and have reached the present invention. Specifically, the ink jet recording paper is provided with an ink receiving layer containing a pigment on at least one side of a base paper, the base paper having a multilayer structure of three or more layers using pulp as a main material, and a surface layer and a back layer. Paper containing regenerated pulp in at least one inner layer formed between and containing 20% by mass or more of regenerated pulp with respect to the total pulp solids, and whiteness with respect to the total solids of regenerated pulp It has been found that the problem can be achieved by using a multilayer paper containing 50% by mass or more of recycled pulp having a content of 60% or more.

  According to the present invention, recycled pulp can be blended in a high amount, and an inkjet recording paper that is environmentally friendly can be obtained. In addition, even if the recycled pulp is highly blended, it is possible to provide postcard paper for ink jet recording suitable for a post transportation system with high whiteness, low fluorescence intensity, little dust and dirt.

  Hereinafter, embodiments of the present invention will be described. The ink jet recording paper of the present invention has an ink receiving layer on at least one surface of a base paper. Hereinafter, the present invention will be described in detail by taking the case of postcard paper for ink jet recording as an example.

<Base paper>
(Structure of the base paper)
The base paper of the present invention has a multi-layer structure of three or more layers using pulp as a main raw material, and is manufactured by papermaking or multi-layer papermaking. For example, in the case of 3 layers, “surface layer”, “middle layer”, “back layer”, in the case of 4 layers, “surface layer” “front layer” “back layer” “back layer”, in case of 5 layers “surface layer” “surface layer” ”,“ Middle layer ”,“ back layer ”, and“ back layer ”. The number of stacked layers is not limited to these. The surface layer includes a stealth barcode printed surface. The inner layer formed between the surface layer and the back layer in the present invention means “front layer”, “middle layer”, and “back layer”.

  The base paper of the present invention has at least one inner layer, that is, for example, in the case of 3 layers, “middle layer”, in the case of 4 layers, “front lower layer” and / or “back lower layer”, in the case of 5 layers “ Any one or more of the “lower layer”, “middle layer”, and “back lower layer” contains recycled pulp made from waste paper as a raw material. In the present invention, by containing recycled pulp in the inner layer as described above, the whiteness is high while the recycled pulp is highly blended, and the influence of dust, dirt, and fluorescent substances contained in the recycled pulp is kept low. It becomes possible. In the present invention, the content of recycled pulp is preferably as much as possible from the viewpoint of the environment, and is 20% by mass or more, more preferably 40% by mass or more, and further preferably 60% by mass or more, based on the total pulp solid content.

(Pulp raw material)
In the present invention, a recycled pulp having a whiteness of 60% or more is used, and by containing 50% by weight or more based on the solid content of the entire recycled pulp, the recycled pulp such as dirt, dust, and fluorescence intensity is increased. In addition to resolving problems when blended, excellent whiteness can be obtained. The whiteness of the recycled pulp is more preferably 65% or more, and further preferably 70% or more. In addition, the whiteness of the pulp in the present invention is measured according to JIS P 8148.

  In the present invention, the ash content in the regenerated pulp is preferably less than 20% by mass and more preferably less than 10% by mass in the regenerated pulp from the viewpoint of reducing dust and dirt. Thus, since there is little ash content in a regenerated pulp, the internal bond strength in a multilayer structure also becomes favorable. Ash content in the recycled pulp can be adjusted by dust removal, deinking, washing with a dehydrator, and the like. Further, by sufficiently performing these treatments, the amount of fine fibers contained in the regenerated pulp is reduced, and the content ratio of fine fibers having a length of 0.1 mm or less is less than 10% by mass, and further less than 5% by mass. It becomes. The ash content in the recycled pulp is measured according to the 525 ° C. combustion method defined in JIS P 8251. The amount of fine fibers is measured according to a fiber length measurement method by an optical automatic analysis method stipulated in JIS P 8226. Specifically, when measured with a pulp analyzer “FiberLab” manufactured by Kajaanisy The frequency of 0.1 mm or less in the fiber length distribution at the time of the average length calculation.

  In the present invention, when the recycled pulp is blended in a plurality of inner layers with four or more layers, the recycled pulp blended in each inner layer may be the same or different. When the whiteness of the regenerated pulp used for each layer is different, for example, when there are 5 or more layers, the whiteness of the regenerated pulp used for the front lower layer and the back lower layer is higher than the whiteness of the regenerated pulp used for the middle layer It is preferable. As a result, when the postcard paper is divided into layers, it is preferable that the whiteness of the front and back lower layer papers is higher than the whiteness of the middle layer paper.

  Furthermore, if necessary, the inner layer can be recycled with one or more of the commonly used papermaking materials such as mechanical pulp (MP), hardwood kraft pulp (LKP), and softwood kraft pulp (NKP). It can be used by mixing with pulp. Examples of the mechanical pulp include groundwood pulp (GP), refiner groundwood pulp (RGP), thermomechanical pulp (TMP), chemithermomechanical pulp (CTMP), chemiground pulp (CGP), semi-chemical pulp (SCP), and the like. . From the environmental viewpoint, it is desirable that the amount of recycled pulp used is large. When the recycled pulp and other pulp are mixed and used, the ratio of the two in each inner layer can be arbitrarily set and is not particularly limited, but recycled pulp: other pulp = 50: 50 to 100: 0 is preferable. is there.

  Used paper for recycled pulp includes high-quality paper, medium-quality paper, low-grade paper, newspaper, flyers, magazines, and other sorts of waste paper, unsorted waste paper mixed with these, copy paper, thermal paper, and carbonless paper. Office waste paper including the like can be suitably used.

  On the other hand, recycled pulp may be added to the surface layer and the back layer, but chemical pulp such as softwood kraft pulp, hardwood kraft pulp, etc. may be used from the viewpoints of product whiteness, fluorescence intensity, dust and dirt, etc. preferable. In particular, since the surface layer determines the appearance of the paper and is also the surface side on which the stealth barcode is printed, 100% by mass of chemical pulp is preferable.

  According to the present invention, it is possible to obtain a postcard paper for ink jet recording excellent in appearance whiteness. As postcard paper for inkjet recording using recycled pulp, the whiteness of the front and back surfaces of the paper is preferably about 74%, but according to the present invention, a whiteness of 76% or more can be obtained.

(Fluorescence deactivation treatment)
In the present invention, it is desirable to subject the recycled pulp to fluorescence deactivation treatment from the viewpoint of lowering the fluorescence intensity. Fluorescence deactivation treatment includes addition of a fluorescence deactivator to the recycled pulp slurry, polyvalent metal treatment, enzyme treatment, peroxide treatment, ozone treatment, masking treatment, treatment of the pulp after deinking with chlorine dioxide, etc. Is mentioned.

  In the present invention, it is desirable to use recycled pulp to which a fluorescence quencher has been added. Examples of the fluorescence quencher include dichloroisocyanurate, N-vinylformamide polymer, aromatic carboxylic acid / amine condensate, and the like, but are not limited thereto.

  The addition amount of the fluorescence deactivator is preferably 0.01 to 2%, more preferably 0.03 to 1.5% in terms of solid content per solid content of the recycled pulp. Even if the amount of the fluorescent deactivator added is large, the effect of removing the fluorescence is peaking out, and when it is too much, the whiteness of the pulp tends to decrease, whereas when the amount of the fluorescent deactivator is too small, the effect is insufficient. It is. In particular, for example, in the case of 5 layers, it is preferable to add to the recycled pulp contained in the front and lower layers and / or the back and bottom layers. It is considered that the detrimental effect of the fluorescent dye derived from recycled pulp can be more efficiently suppressed by deactivating the fluorescent dye present in the inner layer close to the surface layer or the back layer.

  In order to add the fluorescence quencher to the recycled pulp, it is preferable after the production of the recycled pulp. In the present invention, it is presumed that the fluorescence intensity decreases due to the masking action of the fluorescence quencher. If it is added before or during the production of regenerated pulp, it is considered that it does not flow out together with water in the treatment step or does not sufficiently adhere to the pulp fiber due to stirring or the like.

(Paper making method)
The method for producing the base paper of the present invention is not particularly limited, and can be obtained by preparing a stock for each layer, for example, by combining each layer with a long net type wet paper machine to form a multilayer structure. . Moreover, the paper stock of each layer may be ejected from the multi-layer head box to make a multi-layer paper. In addition to the above, examples of the paper machine include a twin wire type paper machine, a circular net paper machine, and a short net paper machine.

  In the present invention, in order to increase the internal bond strength of the multilayer structure, starch or other adhesive may be applied between the layers, or a paper strength enhancer may be blended. However, it is desirable that the internal bond strength is not too high from the viewpoint of disintegration during recycling. In the present invention, JAPAN TAPPI No. The measured value along 18-1 is preferably less than 500 KPa, more preferably 450 KPa or less, and still more preferably 400 KPa or less. Alternatively, JAPAN TAPPI No. The measured value along 18-2 is preferably less than 1650 KPa, more preferably 1600 KPa or less. As a method for obtaining a paper having a multi-layer structure having an internal bond strength in such a range, for example, a layer to which starch and an adhesive are applied and a layer to which a paper strength enhancer is blended are provided, and a layer not containing a paper strength enhancer is provided. However, the present invention is not limited to this.

  In order to prevent the occurrence of paper dust when cutting to a postcard paper size and the peeling of paper during printing or automatic sorter processing, the JAPAN TAPPI No. More than 300 KPa in the measured value according to 18-1, JAPAN TAPPI No. The measured value along 18-2 may be 1300 KPa or more.

(Basis weight)
The basis weight of the base paper is desirably 180 to 200 g / m ² . The basis weight range of each layer in the sheeting can be adjusted within a range not impairing the effect of the present invention, but the basis weights of the surface layer and the back layer are each preferably 20 to 60 g / m ² , 25 More preferably, it is ˜50 g / m ² . If the basis weight of the surface layer and the back layer is too low, there is a concern that the fluorescence intensity derived from the recycled pulp will be high. On the other hand, if the basis weight of the surface layer and the back layer is too high, the surface layer is good in terms of fluorescence intensity and dirt. The amount of chemical pulp used in the back layer is large, which is undesirable from a cost and environmental standpoint.

The basis weight of the inner layer is about 60 to 160 / ^{m 2} is preferred. Moreover, when manufacturing a base paper by making 4 layers or more (inner layer is 2 layers or more), the basis weight of each layer is more preferably 30 to 80 g / m ² . If the basis weight of the inner layer is too low, the proportion of recycled pulp cannot be increased. On the other hand, if the basis weight of the inner layer is too high, the basis weight of the surface layer and the back layer will be reduced, and the fluorescence intensity derived from the recycled pulp will increase. There may be a problem in the readability of the destination information barcode.

(Filler)
The base paper of the present invention may contain a filler. In particular, in order to increase opacity, the surface layer and / or the back layer preferably contains a filler. The type of filler is not particularly limited. For example, calcium carbonate such as heavy calcium carbonate and light calcium carbonate, calcium carbonate-silica composite, titanium oxide, clay, silica, talc, kaolin, calcined kaolin, deramikaolin, magnesium carbonate , Inorganic fillers such as barium carbonate, zinc oxide, silicon oxide, amorphous silica, aluminum hydroxide, calcium hydroxide, magnesium hydroxide, zinc hydroxide, titanium oxide, bentonite; urea-formalin resin, polystyrene resin, melamine resin , Organic fillers such as phenol resin and fine hollow particles can be used alone or in appropriate combination of two or more. In addition, recycled fillers made from papermaking sludge, deinking floss, etc. can also be used. In the case of acidic papermaking, a filler obtained by removing acid-soluble ones from the filler is used, and the filler is used alone or in combination of two or more.

In the present invention, among others, it is recyclable and can improve the opacity and whiteness of the paper at a relatively low cost, so that the pH of the paper surface becomes 6.0 to 9.5 using calcium carbonate. It is preferable to make a paper. If the content of the filler is too small, the opacity is inferior, and if it is too large, paper dust is likely to be generated during offset printing or cutting. The filler content mentioned here includes both those derived from recycled pulp and those added during papermaking.

(Paper chemicals)
In the present invention, various papermaking chemicals can be added as necessary. Specifically, polyacrylamide polymer, polyvinyl alcohol polymer, cationic starch, various modified starches, internal paper strength enhancers such as urea / formalin resin, melamine / formalin resin; rosin sizing agent, AKD type Sizing agents, ASA sizing agents, petroleum sizing agents, internal sizing agents such as neutral rosin sizing agents, and the like. In addition, a retention agent, a drainage improver, a coagulant, a sulfate band, bentonite, silica, a dye, an antifoaming agent, an ultraviolet ray inhibitor, a fading inhibitor, a pitch control agent, a slime control agent, and the like can be used.

(surface treatment)
Moreover, a surface treatment agent can be applied to one side or both sides of the base paper of the present invention as required. There are no particular limitations on the type and composition of the surface treatment agent, but examples of water-soluble polymeric substances for the purpose of improving surface strength include raw starch, oxidized starch, esterified starch, cationized starch, enzyme-modified starch, and aldehyde. Starch such as modified starch, hydroxyethylated starch, hydroxypropylated starch; cellulose derivatives such as carboxymethylcellulose, hydroxyethylcellulose, and methylcellulose; modified alcohols such as polyvinyl alcohol and carboxyl-modified polyvinyl alcohol; styrene-butadiene copolymer, polyvinyl acetate, A vinyl chloride-vinyl acetate copolymer, polyvinyl chloride, polyvinylidene chloride, polyacrylic acid ester, polyacrylamide or the like is used alone or in combination. Further, in the present invention, it is preferable that the Steecht sizing degree is 250 to 600 seconds for writing ability or printing ability with a printer. In order to increase the water absorption resistance, in addition to the water-soluble polymer substance, Surface sizing agents such as styrene acrylic acid, styrene maleic acid, and olefinic compounds may be used in combination. The coating amount of the surface treatment agent is not particularly limited, and is usually about 0.5 to 5 g / m ² per both sides. Further, when a surface treatment agent comprising a water-soluble polymer substance and a surface sizing agent is applied, the mixing ratio of the water-soluble polymer substance and the surface sizing agent may be within a public range.

  Moreover, when apply | coating the surface treating agent mentioned above, the coating apparatus can use what is generally used, for example, 2 roll size press, a gate roll coater, a rod metering size press, a blade coater, a bar blade coater Air knife coaters, curtain coaters, spray coaters, etc. can be used on-machine or off-machine. Furthermore, in the present invention, a calendar process can be applied to the paper surface. There are no particular limitations on the type and processing conditions of the calendar device, and public devices such as ordinary calenders made of metal rolls, soft nip calenders, and high-temperature soft nip calenders are appropriately selected, and according to the quality target values, What is necessary is just to set conditions within the controllable range.

<Ink receiving layer>
In the present invention, an ink receiving layer mainly composed of a pigment and a hydrophilic adhesive is provided on at least one side of the base paper. This ink receiving layer is provided for the purpose of printing with an ink jet printer, and may or may not be considered for offset printing suitability. As the pigment used in the ink receiving layer, a conventionally known white pigment can be used. For example, light calcium carbonate, heavy calcium carbonate, kaolin, talc, calcium sulfate, barium sulfate, titanium dioxide, zinc oxide, zinc sulfide, zinc carbonate, satin white, aluminum silicate, diatomaceous earth, calcium silicate, magnesium silicate, synthetic non Amorphous silica, colloidal silica, colloidal alumina, boehmite, pseudoboehmite, aluminum hydroxide, alumina, lithopone, zeolite, hydrous halloysite, magnesium carbonate, magnesium hydroxide, inorganic pigments, styrene plastic pigment, acrylic plastic pigment, polyethylene Organic pigments such as microcapsules, urea resins, and melamine resins can be used. Of these, synthetic amorphous silica is particularly preferred.

  The hydrophilic adhesive used in the ink receiving layer is not particularly limited, and includes the action of binding pigments to maintain the properties as a coating film, the maintenance of surface strength, and the securing of ink absorbability. Used for purposes. For example, starch derivatives such as oxidized starch, etherified starch and phosphate esterified starch, cellulose derivatives such as carboxymethyl cellulose and hydroxyethyl cellulose, proteins such as casein, gelatin and soy protein, polyvinyl alcohol, polyvinyl pyrrolidone, maleic anhydride resin Water-soluble resins such as styrene-butadiene copolymer, methyl methacrylate-butadiene copolymer, conjugated diene copolymer latex such as vinyl chloride-vinyl acetate copolymer, acrylate ester and methacrylate ester polymer or Acrylic copolymer latex such as copolymer, vinyl copolymer latex such as ethylene-vinyl acetate copolymer, or a functional group-containing monomer such as carboxyl group of these various copolymers. Functional group-modified copolymer latex, melamine resin, water-based adhesive such as a thermosetting resin such as urea resins, polyurethane resins, unsaturated polyester resins, polyvinyl butyral - Le, alkyd resin latex.

  At least one of these adhesives can be used. The blending part number is preferably 20 to 80 parts by mass with respect to 100 parts by mass of the pigment. When the number of blended parts of the binder is small, the surface strength is insufficient, and when it is too large, the ink absorbability is insufficient.

  The ink receiving layer preferably further contains a metal salt or a cationic dye fixing agent. Metal salts and cationic dye fixing agents may be used alone or in combination of two or more.

  In addition, surfactants, sizing agents, pigment dispersants, thickeners, fluidity improvers, antifoaming agents, antifoaming agents, mold release agents, foaming agents, penetrating agents, coloring dyes, fluorescent whitening agents UV absorbers, antioxidants, preservatives, antibacterial agents, water resistance agents, water retention agents, and the like can be appropriately blended.

The coating amount of the ink receiving layer is preferably from 3 to 30 g / ^{m 2,} more preferably from 5 to 20 g / ^{m 2.} If the coating amount is too small, the ink solvent is not sufficiently absorbed, so that blurring is noticeable particularly in an image of a mixed color system. Also, if the coating amount of the ink receiving layer is too large, the coated layer may fall from the base paper to a powder or rub the printed part when making a lithographic roll or making a small decision. Since the surface strength becomes insufficient, such as the coating layer falling off, it is not preferable. Two or more ink receiving layers may be provided.

  In order to provide the ink receiving layer on the surface of the base paper, various coating devices such as various blade coaters, roll coaters, air knife coaters, bar coaters, gate roll coaters, curtain coaters, short dwell coaters, gravure coaters, flexographic coaters. Various apparatuses such as a gravure coater and a size press can be used on-machine or off-machine. In addition, after the ink receiving layer has been applied, the ink receiving layer can be surface-treated with a calendar device such as a machine calendar, a super calendar, or a soft calendar, and the ink receiving layer can be applied using a cast coater or the like. It is possible to work and give glossiness.

(Uses other than postcard paper)
In addition to postcard paper, the ink jet recording paper of the present invention can be used for printing paper, information paper, newsprint, packaging paper, and the like. What is necessary is just to set suitably various physical properties, such as basic weight, a manufacturing method, etc. according to each use.

  Hereinafter, the present invention will be described in more detail based on examples. In addition, this invention is not restrict | limited to an Example. In the examples and comparative examples, parts and% represent solid parts by mass and solids mass%. In the following examples, five layers were combined, and each layer was described in the order of “surface layer”, “front layer”, “middle layer”, “back layer”, and “back layer”.

[Example 1]
[Manufacture of recycled pulp]
(DIP-A)
Waste paper was fed into the high-concentration pulper at a ratio of waste newspaper: magazine waste paper: Kent waste paper: flyer waste paper = 65: 16: 11: 8. The chemical | medical agent was added here and it adjusted so that a pulp density | concentration might be 15 mass%, and the disaggregation process was performed. The chemicals used were 2.0% caustic soda and 0.2% higher alcohol deinking agent in proportion to the weight of used paper. Subsequently, DIP (deinked recycled pulp) was produced through a coarse selection screen, a floater, a selection screen, and a disperser. Formamidine sulfinic acid (FAS) is further added to this DIP, and after dispersion treatment with a disperser, it is diluted with water and washed with a high-speed wire belt type dehydrator (DNT washer). Obtained. The whiteness of DIP-A was 70%, the ash content was 3%, and the amount of fine fibers of 0.1 mm or less was 1.4%.
(DIP-B)
DIP-B was obtained in the same manner as DIP-A, except that the steps after the addition of formamidinesulfinic acid (FAS) were not performed. The whiteness of DIP-B was 55%, the ash content was 12%, and the amount of fine fibers of 0.1 mm or less was 10%.
<Manufacture of base paper>
(Surface and back layers)
Add 100 parts of LBKP beaten to 400 ml of Canadian Standard Freeness (CSF), add 2 parts of calcium carbonate as filler, 0.4 part of internal sizing agent, 0.1 part of retention agent, and 2 parts of sulfuric acid band. A slurry was prepared.
(Front lower layer, back lower layer)
Mixing 50 parts of LBKP (400 ml of CSF) and 50 parts of recycled pulp (hereinafter abbreviated as DIP-A) with a whiteness of 70%, 0.75 parts of an internal sizing agent and 2.5 parts of a sulfuric acid band with respect to the pulp content A slurry was prepared by addition.
(Middle layer)
A slurry was prepared by adding 0.75 parts as an internal sizing agent and 2.5 parts of a sulfuric acid band to 100 parts of recycled pulp (DIP-A) having a whiteness of 70%.
(Making)
The above three types of paper stock slurry were paper-made with a long paper machine so that the surface layer = 28 g / m ² , the lower layer / middle layer / back layer = 44 g / m ² each, and the back layer = 30 g / m ² , Paper was made in a paper state and dried to make a base paper having a basis weight of 190 g / m ² . During the papermaking, a 2.3% aqueous solution of granular starch was spray-coated at a coating amount of 1 g / m ² between each layer except the back layer and the back layer. Polyvinyl alcohol was applied to this base paper with a two-roll size press so that both sides were 1.8 g / m ^2, and calendar treatment was performed so that the Beck smoothness was 30 seconds to obtain a base paper.
<Manufacture of postcard paper for inkjet recording>
50 parts of synthetic amorphous silica (product name: Mizukasil P-50, manufactured by Mizusawa Chemical Co., Ltd.), 50 parts of synthetic amorphous silica (product name: Psyroid P-409, manufactured by Grace Devison), polyvinyl alcohol (product name) : PVA-117, manufactured by Kuraray Co., Ltd.) 30 parts, ethylene vinyl acetate copolymer (product name: BE-585, manufactured by Chuo Rika Kogyo Co., Ltd.), partially saponified polyvinyl alcohol (product name: GL-05, Nihon Gosei) Chemical Co., Ltd.) 10 parts, ink fixing agent (product name: DK6872, manufactured by Seiko PMC) 5 parts, sizing agent (product name: SE2250, manufactured by Seiko PMC), and dilution water are mixed to obtain a solid content of 18%. A paint was obtained.
This paint is applied to one side of the base paper using a bar blade coater so that the coating amount is 9 g / m ² , an ink receiving layer is formed, and calendering is performed to postcard paper for inkjet recording Got.

[Example 2]
In the manufacture of the base paper of Example 1, in the pulp slurry of the lower and lower layers, except for using 50 parts of LBKP and 50 parts of recycled pulp (DIP-A), 100 parts of recycled pulp (DIP-A) was used. In the same manner as in Example 1, a postcard paper for inkjet recording was obtained.

[Example 3]
In the production of the base paper of Example 1, an aromatic carboxylic acid / amine condensate (Satoda processed FQ-50) was used as a fluorescence quencher, LBKP and recycled pulp ( A postcard paper for ink-jet recording was obtained in the same manner as in Example 1 except that 0.05% per pulp combined with DIP-A) was added (equivalent to 0.1% addition to DIP-A).

[Example 4]
In the production of the base paper of Example 1, except that 100 parts of recycled pulp (DIP-B) having a whiteness of 55% was used instead of 100 parts of recycled pulp (DIP-A) in the middle layer pulp slurry. In the same manner as in Example 1, a postcard paper for inkjet recording was obtained.

[Comparative Example 1]
<Manufacture of base paper>
Mix 80 parts LBKP 80 ml with CSF and 20 parts recycled pulp (DIP-A), add 5 parts calcium carbonate as a filler, 1.4 parts internal sizing agent, and 2 parts sulfuric acid band to make a paper slurry. Prepared. This stock slurry is made with a long paper machine so that the basis weight is 190 g / m ^2, and 1.8 g / m ² of polyvinyl alcohol is applied with a size press, and the calendar is adjusted so that the Beck smoothness is 30 seconds. Processing was performed to obtain a base paper.
<Ink receiving layer>
A coating material was prepared in the same manner as in Example 1, and this coating material was applied to one side of the base paper using a bar blade coater so that the coating amount was 9 g / m ² to form an ink receiving layer. Then, a calendar process was performed to obtain a postcard paper for ink jet recording.

[Comparative Example 2]
<Manufacture of base paper>
Mix 60 parts of LBKP (400 ml of CSF) and 40 parts of regenerated pulp (DIP-A), add 5 parts of calcium carbonate as a filler, 1.4 parts of internal sizing agent, and 2 parts of sulfuric acid band to prepare a paper slurry. Prepared. This stock slurry is made with a long paper machine so that the basis weight is 190 g / m ^2, and 1.8 g / m ² of polyvinyl alcohol is applied with a size press, and the calendar is adjusted so that the Beck smoothness is 30 seconds. Processing was performed to obtain a base paper.
<Ink receiving layer>
A coating material was prepared in the same manner as in Example 1, and this coating material was applied to one side of the base paper using a bar blade coater so that the coating amount was 9 g / m ² to form an ink receiving layer. Then, a calendar process was performed to obtain a postcard paper for ink jet recording.

[Comparative Example 3]
Inkjet recording was conducted in the same manner as in Comparative Example 2 except that 40 parts of recycled pulp (DIP-B) having a whiteness of 55% was used instead of 40 parts of recycled pulp (DIP-A) in the production of the base paper of Comparative Example 2. A postcard paper for recording was obtained.

[Comparative Example 4]
In the production of the base paper of Example 2, in the pulp slurry of the lower layer, the middle layer, and the lower layer, except for using 100 parts of recycled pulp (DIP-B) instead of 100 parts of recycled pulp (DIP-B), In the same manner as in Example 2, a postcard paper for inkjet recording was obtained.

[Evaluation method]
The postcard paper for inkjet recording obtained in each example and comparative example was evaluated by the following method. The evaluation results are summarized in Table 1. In the table, the IJ surface is the ink receiving layer surface, and the back surface is the surface without the ink receiving layer.
<Whiteness>
Measurement was performed according to JIS P 8148 for pulp, base paper, and ink-jet recording postcard paper.
<Fluorescence intensity>
According to JIS P 8148, the whiteness (X) when irradiated with light including the ultraviolet region and the whiteness (Y) when irradiated with light not including the ultraviolet ray are measured, and the difference between the two (X−Y) is measured. The fluorescence intensity was determined. It shows that fluorescence intensity is so small that a value is small.
・ Chile Dirt: Visually evaluated and indicated by the following criteria.
◎ Chile Dirt is inconspicuous ○ Chile Dirt is almost inconspicuous △ Chile Dirt is slightly conspicuous, but there is no problem in practical use × Lots of Chile Dirt <DIP fine fiber amount>
A frequency of 0.1 mm or less in the fiber length distribution at the time of length average calculation was measured using a pulp analyzer “FiberLab” manufactured by Kajaanisy.
<Internal bond strength>
JAPAN TAPPI No. 18-1 and no. Measured along 18-2. The former represents tension in the Z-axis direction, and the latter represents internal bonding.
<Automatic sorting machine processing test>
The results of the processing test using the automatic sorting machine are shown below.

○ Good △ Somewhat bad × Bad <Opacity>
The opacity of postcard paper for inkjet recording was measured according to JIS P 8138.
<Beck smoothness>
The Beck smoothness of the IJ surface of the postcard paper for inkjet recording was measured according to JIS P 8119.

表１より、多層構造の基紙を使用した実施例１〜４のインクジェット記録用はがき用紙は、白色性に優れ、蛍光強度が低く、チリやダートも問題ないレベルであり、自動区分機処理の結果が良好であった。中でも、蛍光失活剤を添加した実施例３は、蛍光強度がより低下した。一方、単層抄きで白色度の高い再生パルプを用いた比較例１、２のインクジェット記録用はがき用紙は、蛍光強度が高く再生パルプ由来の蛍光染料の影響が強く、チリやダートも増加した。さらに、単層抄きで白色度の低い再生パルプを用いた比較例３では、白色性に劣り、蛍光強度が高く、チリやダートも増加した。また、多層構造であるものの白色度の低い再生パルプを用いた比較例４では、チリやダートが増加した。

From Table 1, the postcard paper for ink-jet recording of Examples 1 to 4 using a base paper having a multilayer structure is excellent in whiteness, low in fluorescence intensity, and has no problem with dust and dirt. The result was good. In particular, Example 3 to which the fluorescence deactivator was added had a lower fluorescence intensity. On the other hand, the ink-jet recording postcard papers of Comparative Examples 1 and 2 using recycled pulp with high whiteness in single-layer papermaking were highly influenced by fluorescent dyes derived from recycled pulp and increased in dust and dirt. . Furthermore, in Comparative Example 3 in which recycled pulp with low whiteness was used in single-layer papermaking, the whiteness was inferior, the fluorescence intensity was high, and dust and dirt were also increased. Moreover, in Comparative Example 4 using a recycled pulp having a multi-layer structure but low whiteness, dust and dirt increased.

  The ink jet recording paper of the present invention can be used as a postcard capable of environmentally friendly ink jet recording utilizing waste paper.

Claims (3)

A postcard paper for ink jet recording in which an ink receiving layer containing a pigment is provided on at least one side of a base paper, the base paper having a multilayer structure of three or more layers using pulp as a main material, and a surface layer and a back layer. A paper containing recycled pulp in at least one inner layer formed between the front and back layers, each having a basis weight of 20 to 60 g / m ² and 20 mass of recycled pulp relative to the total pulp solids. 50% or more of recycled pulp having a whiteness of 60% or more with respect to the total solid content of the recycled pulp, and 0.01 to 2 in terms of solid content per solid content of the recycled pulp Postcard paper for ink-jet recording , which is a multilayer paper containing 1% of a fluorescence quencher . The ink receiving layer contains synthetic amorphous silica as a pigment, the basis weight of the postcard paper for inkjet recording is 180 to 200 g / m ² , and the basis weight of the total inner layer is 60 to 160 g / m ^2. The postcard paper for ink jet recording according to claim 1. The postcard paper for ink jet recording according to claim 1 , which has a multilayer structure of 3 to 5 layers .