JP5297601B2 - Form paper - Google Patents

Description

  The present invention relates to foam paper. More specifically, the present invention relates to a form paper that is excellent in printing workability such as dimensional stability and paper transportability and is suitable for any form printing such as electrophotographic printing, ink jet printing, and offset printing.

  Form paper on which various types of printing are performed mainly in a winding shape is used as commercial printing, and therefore high quality is required in terms of reproducibility and dimensional stability of various printed images.

  Conventionally, a lot of printing has been performed by offset rotary printing. However, due to recent progress in visualization and IT, full-color printing and variable information printing tend to be performed as a series of printing. For example, fixed information having excellent appearance is a means for performing offset full-color printing or full-color electrophotographic printing, and performing individual variable information by full-color inkjet printing in a subsequent process.

  As foam paper for various printing, for example, foam paper suitable for electrophotographic printing (see Patent Document 1) in which carboxymethyl celluloses are added to deinked waste paper pulp and the surface electrical resistance is adjusted to a predetermined range, For offset rotary printing and NIP printing, a predetermined amount of size press fluid containing a paper strength enhancer containing starch and polyacrylamide blended at a predetermined ratio is attached to a base paper composed mainly of hardwood pulp. Applicable foam paper (see Patent Document 2), and ink jet printing in which the absolute value of the fiber orientation angle and the fiber orientation ratio of the front and back surfaces measured with an optical orientation tester are each set to a predetermined value or less. A form paper (see Patent Document 3) and the like adapted to the above has been proposed.

  However, since these conventional form papers are originally manufactured to be adapted only to individual printing means, their uses are limited, and when used for printing means different from the original, the quality is as follows. I have to make some compromises. Therefore, these are difficult form papers that can be applied to various printing means as required by the trend.

As described above, it is the actual situation that multi-form foam paper has not yet been proposed for various printing means, and can be suitably used for various form printing such as electrophotographic printing, inkjet printing, and offset printing. Development of foam paper is awaited.
JP-A-4-88354 JP 2005-206992 A JP 2005-178015 A

  The present invention has been made in view of the background art, and not only has excellent form printability and dimensional stability, but also excellent print workability such as paper transportability and full color printability, such as electrophotographic printing, An object of the present invention is to provide a form paper suitable for various forms printing such as inkjet printing and offset printing.

That is, the present invention
A foam paper in which a coating layer is formed with a coating agent containing a pigment and an adhesive on both sides of a base paper,
In the coating layer, calcium carbonate having an area average particle diameter of 1.5 to 8.0 μm is contained in an amount of 50 to 100 parts by mass with respect to 100 parts by mass of the pigment, and the adhesive is in a solid content ratio. 2 to 8 parts by mass with respect to 100 parts by mass of the pigment, and a conductive agent,
The basis weight according to JIS P 8124 is 75 to 130 g / m ² ,
Parker print surf rough according to ISO 8791-4 in the standard state according to JIS P 8111, the surface electrical resistance according to JIS K 6911 is 1 × 10 ⁸ to 1 × 10 ¹² Ω, and the front and back surfaces Ri is the difference (absolute value) is 1.00μm / Pa · s der below,
According to JIS Z 0208, at a temperature of 20 ° C. and a relative humidity of 65%, the moisture permeability M ₂₀ is 500 g / m ² · 24 h or less, and in accordance with JIS Z 0208 at a temperature of 40 ° C. and a relative humidity of 65%. moisture permeability _{M 40} is characterized in der Rukoto than 1000g ^/ m 2 · 24h, about the form sheet.

  The foam paper of the present invention not only has excellent form printability and dimensional stability, but also excellent printing workability such as paper transportability and full color printability, such as various types such as electrophotographic printing, ink jet printing, and offset printing. It can be suitably used for any form printing.

(Embodiment)
The foam paper of the present invention has a coating layer formed on both sides of a base paper with a coating agent comprising a pigment containing a specific amount of calcium carbonate, an adhesive and a conductive agent.

  First, the base paper used in the present invention will be described. The base paper is obtained by papermaking a normal raw pulp, and it is preferable to use, as the raw pulp, for example, waste paper pulp made of waste paper that is friendly to the environment in recent years and can effectively use resources. The waste paper pulp includes, for example, tea waste paper, craft envelope waste paper, magazine waste paper, newspaper waste paper, leaflet waste paper, office waste paper, corrugated waste paper, upper white waste paper, Kent waste paper, imitation waste paper, and old paper waste paper. Disintegration / deinking waste paper pulp, disaggregation / deinking / bleaching waste paper pulp, and the like can be used, and one or more of these can be appropriately selected and used.

  Recycled recycled paper pulp, compared to virgin pulp fiber, fluff originally produced on the surface of the fiber is removed by repeated deinking regeneration treatment, resulting in lazy flat pulp fiber. The amount of waste paper pulp is the total amount of raw pulp because there is little entanglement between the fibers at the time of layer formation, and there is a risk of paper dust being generated due to strength reduction or deterioration, or in terms of workability in the form printing machine. It is preferable to be 80% by mass or less. In addition, since the waste paper pulp has extremely excellent dimensional stability due to the repeated deinking regeneration, the amount of the waste paper pulp is preferably 30% by mass or more of the total amount of the raw material pulp. .

  In addition to the waste paper pulp, chemical pulp such as unbleached softwood pulp (NUKP), unbleached hardwood pulp (LUKP), bleached softwood pulp (NBKP), bleached hardwood pulp (LBKP), etc .; Stone Grand Pulp (SGP), Pressurized Stone Grand Pulp (PGW), Refiner Grand Pulp (RGP), Chemi Grand Pulp (CGP), Thermo Grand Pulp (TGP), Grand Pulp (GP), Thermo Mechanical Pulp (TMP), Chemi Thermo Mechanical Pulp (CTMP) From the mechanical pulp such as refiner mechanical pulp (RMP), one or more can be appropriately selected and used as the raw material pulp.

  In the present invention, the raw material pulp is mixed to prepare a papermaking raw material (stock slurry). For the raw material pulp, for example, an internally added sizing agent, a paper strength enhancer, a paper thickness improver, a yield improver, etc. The various additives that are usually blended in foam paper can be internally added by appropriately adjusting the type and blending amount.

  For example, after making a papermaking raw material as described above in a wire part, and then subjecting it to a press part and a pre-dryer part to produce a base paper, and applying a coating agent described later on both sides of the base paper in a coater part, It can be used for a dryer part, a calendar part, a reel part, a winder part, and the like to obtain a base paper of a desired form paper.

  In order to further improve the whiteness of the target foam paper, the whiteness was measured in accordance with JIS P 8148 “Paper, Paperboard and Pulp—Measurement Method of ISO Whiteness (Diffusion Blue Light Reflectance)”. The whiteness of the base paper is preferably 75% or more, more preferably 78% or more. Foam paper manufactured from such a base paper can have a whiteness of 80% or more, more preferably 85% or more. For example, the whiteness is less than 80%. A photo-like finish unique to various full-color printing with high contrast can be obtained. Such whiteness of the base paper and foam paper can be easily achieved by adjusting raw material pulp blending, papermaking conditions, and coating pigments.

Although there is no particular limitation on the basis weight of the base paper, considering that the basis weight according to JIS P 8124 “Paper and paperboard—basis weight measurement method” of the target foam paper is 75 to 130 g / m ² , the basis weight of base paper is preferably adjusted so that normal 65~120g / m ² approximately.

The basis weight of the foam paper of the present invention is 75 to 130 g / m ² . When the basis weight is less than 75 g / m ² , the electric charge easily moves in the front and back direction of the paper in electrophotographic printing, and the printed image is broken before fixing the toner, and the accuracy of the electrophotographic image is impaired. On the other hand, if the basis weight is larger than 130 g / m ² , the electric charge is difficult to move in the front and back direction of the paper, and a portion where the toner does not transfer to the paper is generated, thereby impairing the precision of the electrophotographic image. Thus, for example, in order to obtain printability in electrophotographic printing, the charge mobility in the front and back direction of paper is important, but the basis weight as in the present invention is 75 to 130 g / m ² , preferably 80. By setting it to ˜120 g / m ² , a suitable foam paper can be obtained.

Also, in electrophotographic printing, the adaptability between roll and paper such as toner transfer, overheating fixing with a fixing roll, contact with a cooling roll, etc. is required, so the basis weight of the foam paper provided is still inevitable In the range of 75 to 130 g / m ^{2 as} in the present invention.

Further, also in inkjet printing, the basis weight of the paper is an important factor and affects the ink absorbability and drying properties of the inkjet ink. Therefore, foam paper having a basis weight of 75 to 130 g / m ² is preferably used.

  Next, a coating layer containing a pigment and an adhesive is applied to both sides of the base paper that has been made as described above to provide a coating layer.

  In the present invention, for example, light calcium carbonate or more preferably heavy calcium carbonate is used as the pigment. Examples of heavy calcium carbonate include those having an average particle diameter of about 5 μm or less obtained by dry or wet pulverization of white crystalline limestone. Examples of the light calcium carbonate include those having an average particle size of about several μm and those having an average particle size of about 0.02 to 0.1 μm, which are chemically produced by baking limestone, Examples thereof include columnar, needle-like, and spindle-shaped, as well as a chestnut shape in which crystal structures having these shapes are aggregated and crystallized.

Area average particle diameter of the calcium carbonate contained as a pigment in the coating layer is, 1.5 [mu] m or more on and it is 8.0μm or less, 5. It is preferably 0 μm or less. When the area average particle diameter of calcium carbonate is less than 1.5 μm, the coating layer becomes too dense, and when the form paper is subjected to, for example, ink jet printing, the penetrability of the ink jet ink is lowered, and rubbing during printing. There is a possibility that problems such as printing and set-off may occur, and that various printing presses may cause poor running due to slippage. Conversely, when the area average particle size of calcium carbonate exceeds 8.0 μm, the gap between the particles on the paper surface becomes large, and for example, high-definition printing becomes difficult in offset full-color printing and full-color electrophotographic printing, and form printing. Due to the high-speed roll contact, etc., calcium carbonate may fall out of the coating layer as paper powder, running stability in the printing press may be impaired, and meandering and running failure may occur.

  In the present specification, the area average particle diameter of calcium carbonate in the coating layer refers to a value measured with a scanning electron microscope (model number: S-2150, manufactured by Hitachi, Ltd.).

  The amount of the calcium carbonate contained as a pigment in the coating layer is such that the surface of the coating layer of the foam paper obtained is inadvertently adhered to the rolls of various printing facilities by using the calcium carbonate as a main component. From the point that it does not peel off and is excellent in printability, it is 50 to 100 parts by mass, preferably 60 to 100 parts by mass, and more preferably 70 to 100 parts by mass with respect to 100 parts by mass of the total amount of pigment.

  In addition to the above calcium carbonate, the coating agent used in the present invention includes, for example, kaolin, delaminated kaolin, talc, clay, satin white, calcium sulfite, gypsum, barium sulfate, white carbon, calcined kaolin, and structured kaolin. , Diatomaceous earth, magnesium carbonate, titanium dioxide, aluminum hydroxide, calcium hydroxide, magnesium hydroxide, zinc hydroxide, zinc oxide, magnesium oxide, bentonite, sericite and other inorganic pigments, polystyrene resin fine particles, urea formalin resin fine particles, fine One or more kinds of organic pigments such as hollow particles and porous fine particles can be appropriately selected and blended as a pigment.

  Among the pigments, when clay is used, it is preferably used because the gloss and smoothness of the foam paper are easily improved and the printability is improved. However, if the amount of clay is too large, for example, the absorption drying property of offset ink, the fixing property of toner, the absorption drying property of inkjet ink may be reduced, and the problem of sticking to various rolls may occur. In electrophotographic printing having the above, there is a risk of causing printing failure or running failure. However, when 50 to 100 parts by mass of calcium carbonate is blended as in the present case, the above problem is unlikely to occur.

  There are no particular limitations on the type of adhesive blended in the coating agent together with the pigment, for example, proteins such as casein and soy protein; styrene-butadiene copolymer latex, methyl methacrylate-butadiene copolymer latex, styrene -Conjugated diene latex such as methyl methacrylate-butadiene copolymer latex, acrylic latex such as polymer latex or copolymer latex of acrylate ester and / or methacrylate ester, vinyl such as ethylene-vinyl acetate polymer latex Latexes such as alkali partially soluble or insoluble latexes obtained by modifying these latexes with various functional group latexes such as carboxyl groups; polyvinyl alcohol, olefin-maleic anhydride resins, Mela Synthetic resin adhesives such as styrene resin, urea resin, urethane resin; starches such as oxidized starch, positive starch, esterified starch, dextrin; cellulose derivatives such as carboxymethylcellulose, hydroxyethylcellulose, etc. Adhesives that can be used are exemplified, and one or more of them can be appropriately selected and used.

Percentage of pigment and adhesive in the coating agent is too small amount of adhesive, the formation of the coating layer is not adversely affected, in solid content ratio, 100 parts by weight of the pigment with respect to The adhesive is adjusted to 2 parts by mass or more, and further 5 parts by mass or more. On the contrary, the amount of the pigment is too small, and the effect of improving the printing workability and full color printing suitability of the resulting foam paper is sufficient. to eliminate the risk of not expressed, in solid content ratio, adjust such that the adhesive with respect to 100 parts by weight of the pigment is less than 8 parts by mass.

In the present invention, the coating layer formed by the coating agent is 1. A conductive agent is included together with a pigment having an area average particle diameter of 5 to 8.0 μm and containing 50 to 100 mass% of calcium carbonate as described above.

  Thus, by including a conductive agent in the coating layer, for example, the fixability of the toner is improved in electrophotographic printing, and preferably has an area average particle diameter of 1.5 to 8.0 μm, By mixing calcium carbonate and a conductive agent in the coating layer, dispersibility in the coating layer and unevenness in surface electrical resistance can be reduced.

  The type of the conductive agent used in the present invention is not particularly limited, but for example, an inorganic salt such as sodium chloride (salt), potassium chloride, calcium chloride, magnesium chloride, sodium sulfate, etc .; having a carboxylic acid group and / or a sulfonic acid group Examples thereof include water-soluble polymer compounds and (water-soluble) salts thereof, and one or more of them can be appropriately selected and used.

  Examples of the polymer compound having a carboxylic acid group and a salt thereof include a copolymer of an ethylenically unsaturated comonomer and at least one of acrylic acid and maleic anhydride, a salt thereof, and the like.

  Further, as the polymer compound having a sulfonic acid group, for example, a polymer or copolymer of vinyl aromatic sulfonic acid or a salt thereof is particularly useful. Specific examples thereof include, for example, polystyrene sulfonic acid and polyvinyl benzyl sulfonic acid. And polymers and copolymers of water-soluble salts thereof.

  Examples of the water-soluble salt of the polymer compound include sodium salt, potassium salt, ammonium salt and the like.

  Among various conductive agents, in addition to inexpensive sodium chloride, polyvinylbenzyltrimethylammonium chloride, sodium tripolyphosphate, and commercially available organic conductive agent cationic polymer compound-based conductive agents are preferably used.

The amount of the conductive agent contained in the coating layer is not particularly limited. As will be described later, the surface electrical resistance of the obtained foam paper is 1 × 10 ⁸ to 1 × 10 ¹² Ω according to JIS K 6911. However, it is preferably 0.1 to 2 parts by mass, and more preferably 0.5 to 1.5 parts by mass with respect to 100 parts by mass of the pigment.

  The coating agent used in the present invention includes a pigment containing calcium carbonate, an adhesive, and a conductive agent. In addition to these, for example, a fluorescent whitening agent can be blended.

  The fluorescent whitening agent not only has a whitening effect on paper but also has an effect of improving ink acceptability. For example, a stilbene derivative, particularly a stilbene derivative having 5 sulfonic acid groups is particularly preferably used. Can do.

  The stilbene derivative is generally used as a whitening agent for paper. For example, the whitening effect is further improved by using it together with polyvinyl alcohol which is a material to be dyed. In particular, a stilbene derivative having 5 sulfonic acid groups has a further whitening effect, and among them, a stilbene derivative having 5 sulfonic acid groups in trans form has a high fluorescent whitening intensity and a whitening maintenance period. Since it is long, it is preferable in terms of further improving the whiteness of the foam paper obtained.

  The blending amount of the fluorescent brightening agent is not particularly limited, but is preferably about 0.1 to 5 parts by mass with respect to 100 parts by mass of the pigment from the viewpoint of expression of whitening effect and cost reduction.

  Further, for the coating agent used in the present invention, various commonly used auxiliaries such as a fluorescent whitening material to be dyed, an antifoaming agent, a release agent, a coloring agent, a water retention agent and the like are appropriately blended. You can also.

  The coating of the coating agent on both sides of the base paper is preferably performed, for example, in a coater part between dryer parts which is performed in a plurality of stages, usually two stages of a pre-dryer part and an after-dryer part. The coater part is divided into one layer or multiple layers on the base paper by an on-machine coater or an off-machine coater equipped with a coating device such as a blade coater, air knife coater, transfer roll coater, rod metering size press coater, curtain coater, etc. The coating agent is applied. Among these, it is preferable to use a blade coater because high flatness of the coating layer surface is ensured. In addition, as a drying method in the dryer part, for example, various heating drying methods such as hot air heating, gas heater heating, infrared heater heating and the like can be appropriately employed.

In order to form the coating layer on the base paper, it is preferable to apply 5 g / m ² or more of the coating agent on both sides of the base paper. If the amount of the coating agent is less than 5 g / m ² per side, an uncoated portion tends to occur on the surface of the paper, and there is a risk of missing dots or poor toner transfer. By coating 5 g / m ² or more per side, the surface of the paper is excellent in flatness, for example, there is no blanket stain in offset printing, toner fixability in electrophotographic printing, and the fineness of the printed image is improved. It is possible to easily ensure excellent printability that can be applied to various printing means. The amount of the coating agent is more preferably 6 g / m ² or more and 20 g / m ² or less, and particularly preferably 6 g / m ² or more and 15 g / m ² or less. The excellent printability that can be applied to multiple means is further improved. On the other hand, if the amount of the coating agent exceeds 20 g / m ² per side, the coating layer may be cracked or the productivity may be reduced, leading to an increase in cost.

  In addition, the thickness of the coating layer to be formed is not particularly limited, but considering the improvement in printing workability and full color printing suitability of the foam paper obtained by providing the coating layer, it may be, for example, about 5 to 30 μm. preferable.

  For the purpose of imparting gloss, flatness, and printability, the coating layer can be subjected to a flattening treatment using a combination of an elastic roll and a metal roll, such as a super calender or a soft calender. Unlike conventional machine calendars, these papers can be flattened without excessively increasing the density of the base paper or coating layer by treating the paper surface with a wide surface at a high temperature, for example, offset printing. A suitable printing surface can be formed in electrophotographic printing, ink jet printing, and the like. Among them, a super calender that combines metal rolls and elastic rolls of a predetermined temperature in a plurality of stages in the vertical direction and pressurizes in the vertical direction is heated to about 70 ° C. using hot water. Since it is more economical than the above, it is particularly preferably used.

  The linear pressure, temperature, and speed of calendering are not particularly limited, but in order to sufficiently improve the flatness of the coated layer after treatment and to prevent the final form paper from becoming too tight. For example, in a super calender, the linear pressure is preferably 95 to 300 kN / m, the metal roll temperature is preferably 50 to 90 ° C., and the speed is preferably 500 to 1000 m / min. Under these conditions, the Parker print surf coarseness described later is used. The thickness can be easily adjusted within a predetermined range.

The foam paper of the present invention thus obtained is in accordance with JIS K 6911 “General Test Method for Thermosetting Plastics” according to JIS P 8111 “Paper, Paperboard and Pulp—Standard Condition for Humidity Control and Testing. The surface electrical resistance measured in a standard state in accordance with the above is 1 × 10 ⁸ Ω or more, preferably 1 × 10 ⁹ Ω or more, more preferably 2 × 10 ⁹ Ω or more, and 1 × 10 ¹² Ω or less. Preferably it is 1 × 10 ¹¹ Ω or less, more preferably 9 × 10 ¹⁰ Ω or less. If the surface electrical resistance is less than 1 × 10 ⁸ Ω, the toner moves on the paper between the transfer of the toner and the fixing, and an accurate printed image cannot be formed. On the other hand, when the surface electrical resistance exceeds 1 × 10 ¹² Ω, paper sticking to the photosensitive drum and double paper feeding troubles occur.

  In addition, in this specification, surface electrical resistance is based on the said JISK6911, a super insulation meter (model number: R-503, Kawaguchi Electric Co., Ltd. product) and a normal temperature measurement box (model number: P-601, Kawaguchi Electric ( The value measured in the standard state based on JIS P8111 is used.

  The foam paper of the present invention is a Parker print measured in accordance with the method described in ISO 8791-4 “Paper and paperboard—Roughness / Smoothness Test Method (Air Leakage Method) —Part 4: Print Surf Method”. The surf roughness is preferably 1.50 μm / Pa · s or more, more preferably 1.70 μm / Pa · s or more, particularly 1.80 μm / Pa · s or more, both on the front and back surfaces. It is preferably 50 μm / Pa · s or less, more preferably 3.30 μm / Pa · s or less, and particularly preferably 3.20 μm / Pa · s or less.

  For example, when performing offset full-color printing, full-color electrophotographic printing, and full-color inkjet printing, it can be used as an index of printability in individual printing means in measuring Beck smoothness, Wangken-style smoothness, and optical smoothness. However, it has merits and demerits in grasping the printability suitable for multi-use for various printing. Therefore, according to the present invention, the flatness of the front and back surfaces of the foam paper is evaluated by the Parker print surf roughness capable of measuring the smoothness of a microscopic area of about 5 μm / Pa · s. .

  If the Parker print surf roughness is less than 1.50 μm / Pa · s on either the front surface or the back surface, for example, it may be difficult to obtain a printing surface with high definition and excellent drying properties in ink jet recording. There is. On the contrary, when the Parker print surf roughness exceeds 3.50 μm / Pa · s on either the front surface or the back surface, for example, a high-definition printing surface in offset full-color printing or full-color electrophotographic printing is obtained. May become difficult.

Further, in recent years, as required particularly in commercial printing, in order to reduce the difference between the front and back surfaces of the paper, the difference (absolute value) in the Parker print surf roughness between the front and back surfaces is 1.00 μm / Pa. S or less , 0 . It is preferably 98 μm / Pa · s or less, particularly preferably 0.95 μm / Pa · s or less.

  Thus, the Parker print surf roughness is within the range of 1.50 to 3.50 μm / Pa · s on both the front and back surfaces, and the difference in the Parker print surf roughness between the front and back surfaces (absolute By setting the value to 1.00 μm / Pa · s or less, for example, it is possible to obtain a multi-form paper more suitable for any of various printing methods such as offset full-color printing, full-color electrophotographic printing, and full-color inkjet printing. it can.

  In this specification, Parker Print Surf roughness is based on the above-mentioned ISO 8791-4, and Parker Print Surf (PPS) surface smoothness tester (model name: MODEL M-569, MESSMER BUCHEL) The value measured under the condition that the backing disk is soft rubber and the clamp pressure is 1 MPa. It shows that smoothness is so high that the obtained measured value is small.

  Further, the foam paper of the present invention is based on the method described in JIS P 8147 “Method for testing coefficient of friction of paper and paperboard”. JIS P 8111 “Paper, paperboard and pulp—standard conditions for humidity conditioning and testing” It is preferable that the dynamic friction coefficient measured in the standard state based on is 0.50 to 0.90. If the coefficient of dynamic friction is less than 0.50, the papers are slippery. For example, when electrophotographic printing is to be performed, there is a problem of double feeding where two or more sheets should be supplied one by one, or rolls at the time of printing. There is a risk that the paper transportability may be deteriorated, for example, the paper slips on the top to cause misregistration. On the other hand, if the dynamic friction coefficient exceeds 0.90, the frictional force applied between the papers is large, so the surface of the paper is easily damaged, and glossiness, smoothness, and printability that can be printed in various types may be reduced. is there. The dynamic friction coefficient is further preferably 0.55 or more, particularly preferably 0.60 or more, and further preferably 0.85 or less, particularly preferably 0.80 or less. When the dynamic friction coefficient is in such a range, the paper transportability, glossiness, smoothness, and printability that can be printed in various types are further improved.

  In the form paper of the present invention, the transportability in the electrophotographic printing machine is extremely important, and the dynamic friction coefficient is in the above range in order to achieve a good balance between transportability and printability in multiple applications. For example, it is preferable to adjust the content of calcium carbonate or perform the above-described flattening treatment to give the foam paper obtained a surface property suitable for any of various printing methods.

  In this specification, the coefficient of dynamic friction is based on the horizontal method of JIS P 8147, and a blank form paper is attached to both the horizontal plate and the weight, and the front and back surfaces of these foam papers are arranged to face each other. It means a value measured in a standard state in accordance with JIS P 8111 in such a manner that the front and back surfaces rub against each other at a tensile speed of 200 mm / min.

Further foam sheet of the present invention, JIS Z 0208 in conformity with "moisture permeability test method of dry packing material (cup method)", the temperature 20 ° C., a moisture permeability _{M 20} at a relative humidity of 65% 500g ^/ m 2 · 24h below and, JIS Z 0208 in compliance with, the temperature 40 ° C., Ru der moisture permeability _{M 40} is 1000g ^/ m 2 · 24h or more at a relative humidity of 65%. If M ₂₀ exceeds 500 g / m ² · 24 h, moisture is absorbed and released at room temperature, and paper wrinkles and waves are likely to be distorted, which may reduce dimensional stability. In addition, when M ₄₀ is less than 1000 g / m ² · 24 h, for example, in electrophotographic printing, when heating is performed to fix the toner to the paper, vapor generated by evaporation of moisture inside the paper is difficult to escape to the outside of the paper. There is a risk that local wrinkles, waves, and distortions are likely to occur on the paper. These moisture _{permeability, M 20} is 200g ^/ m 2 · 24h or more, or less 480g ^/ m 2 · 24h, _{and, M 40} is 1100g ^/ m 2 · 24h or more, not more than 1750g ^/ m 2 · 24h preferable. When the moisture permeability is in such a range, the paper is less likely to be wrinkled, waved or distorted.

In the present invention, by adjusting both the moisture permeability M ₂₀ and the moisture permeability M ₄₀ to the above values, a quality that can sufficiently satisfy the excellent dimensional stability and printability as foam paper is ensured. be able to.

In the present specification, the moisture permeability M ₂₀ is based on the cup method of JIS Z 0208. About 10 g of anhydrous calcium chloride is contained in the cup, the temperature in the constant temperature and humidity device is 20 ° C., and the relative humidity is 65. It is a value obtained by measuring the moisture permeability of foam paper (sample), calculated from the moisture permeability measured 6 hours after being held in%.

Further, in this specification, the moisture permeability M ₄₀ is based on the cup method of JIS Z 0208, and about 20 g of water containing 0.5% by weight of a polyacrylate highly water-absorbent resin is contained in the cup. A value obtained by measuring the moisture permeability of foam paper (sample), calculated from the moisture permeability measured 6 hours after holding the temperature inside the humidity control device at 40 ° C. and the relative humidity at 65%.

  As described above, in the present invention, not only the roughness of the paper surface but also the surface property of the dynamic foam paper is adjusted, and the dynamic friction coefficient on the front and back surfaces of the foam paper is appropriately adjusted, so that In addition to excellent form printability and dimensional stability, it is possible to obtain a form paper that is particularly excellent in paper transportability, electrophotographic printability, and full-color printability.

  The foam paper of the present invention has a coating layer formed on both sides of a base paper by applying a coating agent comprising a calcium carbonate-containing pigment, an adhesive and a conductive agent, and the basis weight and surface electrical resistance are specified. Because it is adjusted to the range, it not only has excellent form printability and dimensional stability, but also excellent in paper transportability, electrophotographic printability, and full-color printability, such as electrophotographic printing, inkjet printing, offset printing, etc. It can be suitably used for any of the various forms printing.

  Next, although the foam paper of this invention is demonstrated in detail based on an Example, this invention is not limited only to these Examples.

Examples 1 to 4 and Comparative Examples 1 to 13 (Manufacture of foam paper)
First, pigments, adhesives and conductive agents were mixed and stirred at room temperature in the types and ratios shown in Tables 1 and 2 to obtain coating agents. The pigments, adhesives and conductive agents used are as follows. Moreover, the compounding quantity of the adhesive agent and electrically conductive agent of Table 1 and Table 2 is a value with respect to 100 mass parts of pigments.
(Pigment)
# 90 (wet heavy calcium carbonate, product number: ESCALON # 90, manufactured by Sankyo Flour Milling Co., Ltd.)
# 800 (wet heavy calcium carbonate, product number: Escalon # 800, manufactured by Sankyo Flour Milling Co., Ltd.)
・ First grade (wet heavy calcium carbonate, product number: Escalon first grade, Sankyo Flour Milling Co., Ltd.)
・ Clay (kaolin clay, product number: HYDRASPERS90, manufactured by HUBER)
(adhesive)
・ Styrene-butadiene latex (Part No .: PA5036, manufactured by Nippon A & L Co., Ltd.)
(Conductive agent)
・ Salt (Product No .: Normal salt, Naruto Salt Industry Co., Ltd.)

  Next, as a raw material pulp, LBKP and NBKP are blended at a ratio (mass ratio) of 80:20, and each 100 parts by mass (absolutely dry amount) of the pulp is a solid component, and an internal sizing agent (product number) : AK-720H, manufactured by Harima Kasei Co., Ltd.) 0.02 parts by mass, cationized starch (product number: Amilofax T-2600, manufactured by Abebe Japan Co., Ltd.) 1.0 part by mass, and yield improver (product number) : NP442, manufactured by Nissan Eka Chemicals Co., Ltd.) 0.02 part by mass was added to obtain a pulp slurry.

  Next, using a paper making system including a wire part, a press part, a pre-dryer part, a coater part, an after-dryer part, a calendar part, a reel part and a winder part, the resulting pulp slurry is made into paper by the wire part, and then pressed. Part and pre-dryer part were used to produce base paper. Next, in the coater part, the coating agent prepared as described above was applied to both sides of the base paper so that the coating amount per one side was as shown in Table 1 and Table 2, and the thickness was about 6 to 10 μm. A coating layer was formed.

  Next, the base paper with the coating layer formed on both sides is applied to the after dryer part, the coating layer is dried, and the surface of the coating layer is flattened by the calendar part, and then applied to the reel part and winder part. A foam paper was obtained.

  In addition, the wire part made paper using a hybrid former, and the coater part used a blade coater. In the calendar part, a supercalender was used, and a flattening process was performed under the conditions shown in Table 3.

  Furthermore, the area average particle diameter of calcium carbonate contained in the coating layer was measured using a scanning electron microscope (model number: S-2150, manufactured by Hitachi, Ltd.). In the measurement, ten sheets of the paper surface were photographed at a magnification of 12,000 times, and the photographed calcium carbonate particles were measured at five points for each photograph, for a total of 50 points. Since the calcium carbonate particles are not perfect circles, the diameter of the perfect circle drawn so as to have the same area as the area of the particles was defined as the area particle diameter, and the average of these 50 points was defined as the area average particle diameter. The results are also shown in Table 1 and Table 2.

  Each physical property of the obtained foam paper was examined by the following method. The results are shown in Tables 4 and 5.

In addition, the physical properties of the following commercially available papers were similarly examined. The results are also shown in Table 5 as Reference Examples 1 to 3. In addition, about the composition and coating amount of the coating agent regarding these commercially available paper, and the planarization process conditions, it shows together in Table 2 and Table 3.
Reference Example 1 Inkjet paper (digital camera print paper, basis weight: 80 g / m ² ,
Daio Paper Co., Ltd.)
Reference Example 2 Coated paper (Utrilogros mat, basis weight: 84.9 g / m ² ,
Daio Paper Co., Ltd.)
Reference Example 3 Foam paper (New Bright W, basis weight: 64 g / m ² , manufactured by Daio Paper Co., Ltd.)

(A) Basis weight Measured according to the method described in JIS P 8124 "Paper and paperboard-Basis weight measurement method".

(B) Surface electrical resistance Super insulation meter (model number: R-503, manufactured by Kawaguchi Denki Co., Ltd.) and room temperature measurement box (model number: P-601, manufactured by Kawaguchi Electric Co., Ltd.) and measured in a standard state in accordance with JIS P 8111 “Paper, paperboard and pulp—standard state for humidity conditioning and testing”.

(C) Parker Print Surf Roughness According to the method described in ISO 8791-4 “Paper and Paperboard—Roughness Smoothness Test Method (Air Leakage Method) —Part 4: Print Surf Method”, Parker Print -Using a surf (PPS) surface smoothness tester (model name: MODEL M-569, manufactured by MESSMER BUCHEL), measurement was performed under the condition that the backing disk was a soft rubber and the clamp pressure was 1 MPa.

(D) Coefficient of dynamic friction In accordance with the horizontal method described in JIS P 8147 “Friction coefficient test method for paper and paperboard”, blank paper is attached to both the horizontal board and the weight, and the front and back surfaces of these foam papers are relative to each other. JIS P 8111 “Paper, paperboard and pulp—standard conditions for humidity conditioning and testing” so that the front and back surfaces rub against each other at a tensile speed of 200 mm / min. Measured in a standard state in accordance with.

(E) Moisture permeability M ₂₀
In accordance with JIS Z 0208 “Moisture permeability test method for moisture-proof packaging materials (cup method)”, about 10 g of anhydrous calcium chloride is placed in the cup, the temperature in the constant temperature and humidity device is 20 ° C., and the relative humidity is 65%. The moisture permeability of the foam paper (sample) calculated from the moisture permeability measured 6 hours after holding was measured.

(F) Moisture permeability M ₄₀
In accordance with JIS Z 0208 “Water vapor permeability test method for moisture-proof packaging materials (cup method)”, about 20 g of water containing 0.5% by weight of polyacrylate-based superabsorbent resin is placed in the cup, and is kept at constant temperature and humidity. The moisture permeability of the foam paper (sample), which was calculated from the moisture permeability measured after 6 hours while maintaining the temperature inside the apparatus at 40 ° C. and the relative humidity at 65%, was measured.

(G) Whiteness Measured according to the method described in JIS P 8148 “Paper, paperboard and pulp—Measurement method of ISO whiteness (diffuse blue light reflectance)”.

  Furthermore, each characteristic was investigated about each form paper based on the following test examples 1-5. The results are shown in Table 6. The characteristics of the commercially available paper were also examined in the same manner. The results are also shown in Table 6 as Reference Examples 1 to 3.

Test Example 1 (Electrophotographic printability)
Using a laser printer (trade name: IRC3220, manufactured by Canon Inc.), 500 copies were printed on the surface of the foam paper. A black, indigo, red, yellow solid part and a patch of characters are prepared as a printing surface, and this printing surface is observed visually and with a magnifying glass (10 times), and the surface feeling (gloss unevenness, printing unevenness, and unevenness). ) Was evaluated based on the following evaluation criteria.
(Evaluation criteria)
(Double-circle): There is no gloss unevenness, printing unevenness, and uneven feeling at all, and a surface feeling is very favorable.
A: There is almost no gloss unevenness, printing unevenness, and unevenness, and the surface feeling is good.
Δ: Any one of gloss unevenness, printing unevenness and unevenness is recognized, and the surface feeling is slightly inferior.
X: Glossy unevenness, printing unevenness and uneven feeling are recognized, and the surface feeling is clearly inferior.
Of the above evaluation criteria, the cases of ○ and ○ are judged to be actually usable.

Test example 2 (offset printing suitability)
Using an offset printing machine (model number: Lysopia L-BT3-1100, manufactured by Mitsubishi Heavy Industries, Ltd.), color ink (product number: ADVAN, manufactured by Dainippon Ink & Chemicals, Inc.) with four colors on the surface of form paper 5000 copies were printed. The printed surface was observed visually and with a magnifying glass (10 times), and the number of white spots on the printed surface per 100 cm ² was counted and evaluated based on the following evaluation criteria.
(Evaluation criteria)
A: The number of white spots is less than 1, and the printability is very excellent.
◯: There are 2 or more white spots and less than 3 and excellent printability.
Δ: The number of white spots is 3 or more and less than 4, and the printability is slightly inferior.
X: The number of white spots exceeds 4, and the printability is very poor.
Of the above evaluation criteria, the cases of ○ and ○ are judged to be actually usable.

Test Example 3 (Inkjet printing suitability)
Using a water-based inkjet printer (model number: Scitex 6240J, manufactured by Cytex), solid printing and line-printing were performed on the surface of foam paper with ink for inkjet printers (black, product number: Cytex 1040, manufactured by Cytex). . The printed surface was visually observed, and the image quality (the blur of the solid portion and the image portion) was evaluated based on the following evaluation criteria.
(Evaluation criteria)
A: There is no blur at all in the solid part and the image line part, and the image is clear and has high image quality.
○: Slight bleeding is observed in the solid portion or the image portion, but the image quality has no practical problem.
(Triangle | delta): There is much blur of an image line part and it is a somewhat unclear image quality.
X: Both the solid part and the image line part have significant blurring and unclear image quality.
Of the above evaluation criteria, the cases of ○ and ○ are judged to be actually usable.

Test example 4 (paper transportability)
In the electrophotographic printing of Test Example 1, the number of printing troubles such as double feeding and paper jam during printing was evaluated based on the following evaluation criteria.
(Evaluation criteria)
A: There is no printing trouble and the paper transportability is good.
○: A printing trouble occurred once, but there is no practical problem.
(Triangle | delta): A printing trouble generate | occur | produces twice and has a problem practically.
X: Printing trouble occurs three times or more, and the paper transportability is inferior.
Of the above evaluation criteria, the cases of ○ and ○ are judged to be actually usable.

Test Example 5 (Dimensional stability)
Of the printed surfaces obtained in Test Example 1 and Test Example 2, the printed surface of Test Example 1 or Test Example 2 with larger wrinkles and distortions is visually observed and is based on the following evaluation criteria. evaluated.
(Evaluation criteria)
A: There is almost no wrinkle or distortion among waves.
◯: Slight wrinkles and distortion are observed, but there are no practical problems.
(Triangle | delta): A wrinkle and distortion are recognized clearly among waves, and may become a problem in practical use.
X: Wave, wrinkle, distortion is remarkable.
Of the above evaluation criteria, the cases of ○ and ○ are judged to be actually usable.

Each of the foam papers of Examples 1 to 4 has a pigment containing 50 to 100% by mass of calcium carbonate having an area average particle diameter of 1.5 to 8.0 μm, and a solid content ratio of 2 to A coating layer is formed by applying a coating agent consisting of 8 parts by weight of an adhesive and a conductive agent. Difference in basis weight, surface electrical resistance, and Parker print surf roughness on the front and back surfaces (absolute value) ) Is adjusted to a specific range , and the moisture permeability at a temperature of 20 ° C. and a relative humidity of 65% and the moisture permeability at a temperature of 40 ° C. and a relative humidity of 65% are both adjusted to a specific range . Therefore, the foam papers of Examples 1 to 4 are excellent in all of electrophotographic printability, offset printability, and inkjet printability, and are extremely excellent in paper transportability and dimensional stability , particularly dimensional stability . It has characteristics suitable for all forms printing.

On the other hand, the foam papers of Comparative Examples 1 to 13 have the composition and basis weight of the coating agent, the surface electrical resistance, the difference in parker print surf roughness on the front and back surfaces (absolute value) , and the moisture permeability. Since it is not specified as in Examples 1 to 4 , it is inferior to any of electrophotographic printability, offset printability, inkjet printability, and printing workability, and has suitable characteristics for any of various forms printing. Is a difficult thing.

Similarly, the commercially available papers of Reference Examples 1 to 3 have the same composition, basis weight, surface electric resistance, difference in Parker, print, and surf roughness (absolute value) , and moisture permeability. Since it is not specified as in Examples 1 to 4 , it is still inferior to any of electrophotographic printability, offset printability, inkjet printability, and printing workability, and has suitable characteristics for any of various forms printing. It is difficult to be.

  The foam paper of the present invention can be suitably used for any form printing such as electrophotographic printing, ink jet printing, offset printing, and the like.

Claims (2)

A foam paper in which a coating layer is formed with a coating agent containing a pigment and an adhesive on both sides of a base paper,
In the coating layer, calcium carbonate having an area average particle diameter of 1.5 to 8.0 μm is contained in an amount of 50 to 100 parts by mass with respect to 100 parts by mass of the pigment, and the adhesive is in a solid content ratio. 2 to 8 parts by mass with respect to 100 parts by mass of the pigment, and a conductive agent,
The basis weight according to JIS P 8124 is 75 to 130 g / m ² ,
Parker print surf rough according to ISO 8791-4 in the standard state according to JIS P 8111, the surface electrical resistance according to JIS K 6911 is 1 × 10 ⁸ to 1 × 10 ¹² Ω, and the front and back surfaces Ri is the difference (absolute value) is 1.00μm / Pa · s der below,
According to JIS Z 0208, at a temperature of 20 ° C. and a relative humidity of 65%, the moisture permeability M ₂₀ is 500 g / m ² · 24 h or less, and in accordance with JIS Z 0208 at a temperature of 40 ° C. and a relative humidity of 65%. moisture permeability _{M 40} is characterized in der Rukoto than 1000g ^/ m 2 · 24h, form paper. The coating layer is flattened by a combination of an elastic roll and a metal roll,
The foam paper according to claim 1, wherein the dynamic friction coefficient according to JIS P 8147 is 0.50 to 0.90 in a standard state according to JIS P 8111.