JP2011026721A - Form paper - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a form paper hardly causing strike through of a printed information while having light weight, and having not only offset printability but also inkjet printability not causing bleeding or the like. <P>SOLUTION: The form paper is obtained by coating a water-soluble resin coating liquid at least on one surface of a base paper composed of a raw material pulp and a filler as components. The form paper has ≤70 g/m<SP>2</SP>of basis weight measured based on JIS P 8124, and the coating liquid contains a paper-strengthening agent, an olefin-based sizing agent and a water-soluble polyamine-based resin. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a foam paper that can also be used for ink jet printing. More specifically, the present invention relates to a form paper suitable for inkjet printing after offset printing is performed and processed into a continuous slip application.

  Generally, form paper is supplied to an offset rotary printing press in a winding form, and after being printed in a single color or multicolor on this offset rotary printing press, form processing such as perforation processing, punch hole processing, folding processing, etc. Is given.

  In the offset rotary printing process, the problem of white spots occurs due to a decrease in surface strength due to ink tack or fountain solution, and in the case of multicolor printing, the problem of misregistration between colors occurs. There is a need for foam paper that is strong and has excellent dimensional stability. In particular, since form paper is usually used for commercial purposes, high quality is required in terms of reproducibility and dimensional stability of various printed images.

  Conventionally, form paper is usually printed by an offset rotary printing press, but with recent progress in visualization and IT, offset rotary printing and in-jet printing tend to be performed as a series of printing. is there. For example, fixed information such as a standard print pattern is offset full color printing, and variable information such as customer information is inkjet full color printed in a later process.

  This ink jet printing requires that no ink bleeds or that the printed part is clear, and that the printed part is rubbed against the roll of the printing machine, etc. It is required that the ink does not become dirty, and therefore, the drying property (setting property) of the ink is required. In addition, there is also a demand for characteristics (water resistance) that prevents a printed portion printed by an ink jet printer from bleeding even when wet. In other words, it is desired that current form paper has both offset printability and inkjet printability.

  In this regard, as a conventional foam paper, for example, a size press liquid containing a paper strength enhancer containing starch and polyacrylamide is attached to a base paper made using a pulp mainly composed of beaten LBKP. Has been proposed (see, for example, Patent Document 1). This form paper has been proposed as being capable of preventing the occurrence of peeling, vessel picking and white spots in multicolor printing. However, this form paper is not suitable for ink jet printing and cannot prevent ink bleeding.

  In addition, as a conventional form paper, a paint containing a cationic resin ink fixing agent, a sizing agent, etc. was applied to a base paper having a specified Steecht sizing degree, and the Steecht sizing degree was adjusted to a specific range. The thing is proposed (for example, refer patent document 2). This foam paper has been proposed as having low dot bleeding, sufficient water resistance, and excellent ink absorption. Further, as conventional foam paper, one in which fiber orientation angles and fiber orientation ratios on the front and back surfaces are specified has been proposed (see, for example, Patent Document 3). This form paper has been proposed as being capable of preventing curling or cockling that occurs during folding and when it is used in a folded state and during printing. However, since these foam sheets have insufficient surface strength, they are peeled off by ink tack or dampening water during offset printing, resulting in the problem of white spots.

  Furthermore, since the above conventional form papers are originally developed to be adapted only to individual printing means, the printing means are limited, and when subjected to different printing means, the quality is naturally compromised to some extent. I have to do it.

On the other hand, the basis weight of foam paper is preferably 80 g / m ² or more from the viewpoint of preventing back-through during ink jet printing. In Japan, we are actively working on measures such as resource saving, weight reduction and recycling. As for foam paper, if the weight is reduced, the production area will increase even if the production volume is the same. Therefore, it is possible to reduce carbon dioxide emissions per 1 m ² due to incineration after production, transportation and use. However, simply by reducing the basis weight from 80 g / m ² to 70 g / m ² or less because of resource saving, it leads to print information back-through and bleeding, and deterioration in recording suitability in high-speed form printing. None of the above conventional form sheets solves this problem.

JP 2005-206992 A JP-A-10-166713 Japanese Patent Laid-Open No. 2005-178015

  SUMMARY OF THE INVENTION The main problem to be solved by the present invention is to provide a foam paper that is lightweight but does not show through print information, and that has offset printing suitability and ink jet printing suitability such as no bleeding. is there.

The present invention that has solved this problem is as follows.
[Invention of Claim 1]
A foam paper in which a water-soluble resin coating liquid is coated on at least one side of a base paper containing raw pulp and filler,
The basis weight according to JIS P 8124 is 70 g / m ² or less,
The coating liquid contains at least a paper strength enhancer, an olefin sizing agent, and a water-soluble polyamine resin.
Form paper characterized by that.

[Invention of Claim 2]
The coating amount per one side 0.001 to 0.01 g / m ² of the olefinic sizing agent, coating amount of the water-soluble polyamine resin is a single-sided per 0.1 to 1.0 g / m ² ,
The foam paper according to claim 1.

[Invention of Claim 3]
More than 50% of the filler is calcium carbonate,
The filler containing calcium carbonate is blended 3 to 12% in the base paper,
The opacity according to JIS P 8149 is 80 to 90%,
The foam paper according to claim 1 or 2.

[Invention of Claim 4]
The coating amount of the paper strength enhancer is 0.5 to 4.0 g / m ² per side,
The foam paper of any one of Claims 1-3.

  According to the present invention, it is a foam paper that is lightweight but does not show through print information, and has an ink-jet printability such as offset printability and no bleeding.

Next, a mode for carrying out the invention will be described in detail.
The foam paper of this embodiment is obtained by applying a water-soluble resin coating liquid on one or both surfaces of a base paper containing raw material pulp and filler, and has a basis weight in accordance with JIS P 8124. The coating liquid contains at least a paper strength enhancer, an olefin sizing agent, and a water-soluble polyamine resin at 70 g / m ² or less.

[Base paper]
(Raw pulp)
The base paper suitably used for the foam paper of this embodiment is obtained by neutral papermaking containing waste paper pulp, and is excellent in dimensional stability, high tensile strength, low cost and environmentally friendly Is.

  There is no particular limitation on the type of waste paper pulp contained in the base paper. For example, tea waste paper, craft envelope waste paper, magazine waste paper, newspaper waste paper, reprinted paper, plasterboard waste paper, flyer waste paper, office waste paper, cardboard waste paper, upper white Waste paper pulp manufactured from waste paper, Kent waste paper, imitation waste paper, and old paper waste paper can be used, and one or more of these can be appropriately selected and used. In addition, as a raw material for waste paper pulp, it is also possible to use city-collected waste paper, waste products generated in the paper making process, and the like.

  In addition to the above waste paper pulp, for example, hardwood bleached kraft pulp (LBKP), softwood bleached kraft pulp (NBKP), hardwood unbleached kraft pulp (LUKP), softwood unbleached kraft pulp (NUKP), hardwood half Chemical pulp such as bleached kraft pulp (LSBKP), softwood semi-bleached kraft pulp (NSBKP), hardwood sulfite pulp, coniferous sulfite pulp, stone grand pulp (SGP), pressurized stone grand pulp (PGW), refiner grand pulp (RGP) ), Thermo-Grand Pulp (TGP), Chemi-Grand Pulp (CGP), Ground Pulp (GP), Thermo-mechanical Pulp (TMP) and other mechanical pulp, chemically or mechanically from non-wood fibers such as kenaf, hemp and straw Among these, well-known pulp such as pulp manufactured in Seed or more suitably selected and may be used.

  However, in general, hardwood is shorter and thinner than conifers, so the shrinkage of fibers due to humidity is small and dimensional stability is good. Therefore, LBKP, LUKP, LSBKP, etc. should be used in combination with waste paper pulp. Is preferred. Also, pulp made from hardwood has the characteristics that flatness is likely to occur and a smooth and dense paper layer can be formed, as used in printing writing paper, so we use waste paper pulp as raw pulp. In the neutral paper making, when a pulp made of hardwood is used in combination, a foam base paper excellent in dimensional stability, high tensile strength, low cost and environmentally friendly, or foam paper using this base paper is obtained.

  The content of waste paper pulp in the base paper is 5 to 30% by mass of the total amount of raw material pulp. When the content of the used paper pulp is less than 5% by mass of the total amount of the raw material pulp, there arises a disadvantage that the pH of the paper surface cannot be made neutral.

  Recycled recycled paper pulp, compared to virgin pulp fiber, fluff originally produced on the fiber surface fell off by repeated deinking regeneration treatment, and became a lazy flat pulp fiber, There is little entanglement between the fibers at the time of forming the paper layer, there is a risk of paper dust being generated due to strength reduction or deterioration, and there is a risk of quality deterioration in terms of workability in the form printing process. Therefore, the amount of waste paper pulp is preferably 30% by mass or less of the total amount of raw material pulp. However, waste paper pulp has properties that are extremely excellent in dimensional stability due to repeated deinking regeneration treatment over and over, and therefore, the amount of waste paper pulp is preferably 5% by mass or more of the total amount of raw pulp. .

  Preferably, it is preferable to use a raw pulp in which hardwood kraft pulp is a main component (preferably 70% by mass or more) and used paper pulp is combined with this. In particular, the blending ratio of hardwood kraft pulp and waste paper pulp is more preferably 70 to 95: 5 to 30, and particularly preferably 70 to 90:10 to 30. By setting the blending ratio of hardwood kraft pulp in the raw material pulp to 70 to 95% by mass, a water-soluble resin coating liquid composed of a combination of a paper strength enhancer, an olefin-based sizing agent, and a water-soluble polyamine resin is used as a base. Coating can be performed without penetrating excessively into the paper. Further, by containing 5 to 30% by mass of waste paper pulp that is relatively flat compared to virgin pulp, the surface of the base paper is flattened to reduce gaps, and a paper strength enhancer, an olefinic sizing agent, and water The base paper surface can be uniformly coated by uniformly applying a water-soluble resin coating solution composed of a combination of a functional polyamine resin.

  In this embodiment, the weight average fiber length of the pulp fibers after the base paper is disaggregated according to the method described in JIS P 8220 “Pulp-Disaggregation method” (measured with a Kayani average fiber length tester: Fiber Labo) However, it is 0.4 mm or more, preferably 0.6 mm or more, and 0.9 mm or less, preferably 0.8 mm or less. When the weight average fiber length is shorter than 0.4 mm, the gap between the fibers is narrow and the entanglement of the pulp fibers is strong, so that the expansion and contraction of the pulp fibers occurs when moisture is absorbed and released, and the dimensions of the base paper Change will be greater. On the other hand, when the weight average fiber length exceeds 0.9 mm, in ink jet printing which is one of the recording means in the present invention, it is good in terms of dimensional stability with respect to the ink jet ink, but the gap between the fibers becomes large, and the fibers are As a result, the longitudinal tensile strength of the base paper decreases. In addition, in neutral papermaking when the raw material pulp contains waste paper pulp, the weight average fiber length after disaggregation according to the method described in JIS P 8220 of the base paper is 0.4 to 0.9 mm. In addition to being lightweight, there is no see-through of printing information, and it has offset printing suitability and ink jet printing suitability such as no bleeding, excellent dimensional stability, high tensile strength, low cost and environment -Friendly foam paper can be obtained.

  The method for adjusting the weight average fiber length is not particularly limited, but can be performed by a conventionally known beating process or sorting of used paper. Particularly, OA waste paper has a raw material structure similar to that of foam paper. Is preferably used.

  In this embodiment, the weight average fiber length after the base paper is disaggregated in accordance with the method described in JIS P 8220 is defined in the raw material pulp before the paper making is based on fine fibers derived from waste paper. When making paper, the fiber composition changes due to dehydration under the paper making wire or in the press process. Therefore, to accurately specify the paper quality of the foam base paper, the weight average of the foam base paper itself This is because it is necessary to measure the fiber length.

  The pulp beating degree (CSF) used for the base paper of this embodiment is preferably adjusted to 400 to 550 mL, particularly 400 to 500 mL. When the CSF is less than 400 mL, when the hardwood kraft pulp is the main component, a decrease in tensile strength and tear strength is observed, and paper breaks and paper dust are likely to occur during high-speed form printing. Also, when the CSF is less than 400 mL, As the beating progresses, the proportion of the pulp having a short fiber length increases, the entanglement between the fibers becomes strong, and the expansion and contraction due to moisture absorption and desorption may increase. On the other hand, if the CSF exceeds 550 mL, uneven texture tends to occur, resulting in a problem of lack of absorption drying and fineness during ink jet printing. Moreover, when the CSF exceeds 550 mL, the ratio of the pulp having a long fiber length is increased, which is good in terms of dimensional stability, but the entanglement between the fibers is reduced, the tensile strength is reduced, and a paper break trouble occurs during processing. There is a fear. In addition, in the neutral papermaking when the raw material pulp contains waste paper pulp, by making the CSF of the pulp used for the base paper be 400 to 550 mL, there is no show-through of printing information while being lightweight, In addition to the offset printability, it is possible to obtain a foam paper having inkjet printability such as no bleeding. Furthermore, by adjusting to become the above CSF, the coating liquid easily penetrates into the base paper, but each contains a paper strength enhancer, an olefin sizing agent, and a water-soluble polyamine resin within a predetermined range. The viscosity of the coating liquid can be set to a relatively high value of 10 to 30 mPa · s by suppressing the penetration of the coating liquid into the base paper, and the coating liquid remains on the base paper surface. As a result, a foam paper having ink jet suitability can be obtained.

  In the present specification, the pulp beating degree refers to Canadian Standard Freeness (CSF) measured according to the method described in JIS P 8121 “Pulp Freeness Test Method”. The beating for adjusting the CSF can be performed using a double disc refiner (DDR).

  On the other hand, the CSF of hardwood kraft pulp used as a main component of raw material pulp is preferably 400 to 550 mL, more preferably 450 to 500 mL.

  In this embodiment, the above raw material pulp is mixed to prepare a papermaking raw material (raw material slurry). In addition to the filler, the raw material pulp includes, for example, an internal sizing agent, a paper strength enhancer, and a paper thickness improver. In addition, various additives such as a yield improver, which are blended in ordinary foam paper, can be internally added by appropriately adjusting the kind and blending amount thereof. This papermaking raw material is, for example, made in a wire part, then used in a press part, a pre-dryer part, etc. as a base paper, and a water-soluble resin coating solution is applied to one or both surfaces of this base paper in a coater part. Coat and use for after-dryer part, calendar part, reel part, winder part, etc. to make the desired form paper.

(Internal sizing agent)
In this embodiment, the base paper contains, for example, an alkyl ketene dimer (hereinafter also referred to as “AKD”), an alkenyl succinic anhydride (hereinafter also referred to as “ASA”), a rosin emulsion, a styrene-based size as an internal sizing agent. Such known sizing agents can be internally added.

Inner addition amount of sizing agent is preferably 0.01 to 0.5 g / m ^2, more preferably 0.02~0.15g / m ^2. In the case where the basis weight according to JIS P 8124 is 70 g / m ² or less, a coating liquid containing at least a paper strength enhancer, an olefin sizing agent, and a water-soluble polyamine resin is provided on the surface of the base paper. Due to the synergistic effect, the coating amount of the olefin sizing agent is 0.001 to 0.01 g / m ² per side, and the coating amount of the water-soluble polyamine resin is 0.1 to 1.0 g per side. By combining with / m ² , it is possible to obtain a foam paper that is lightweight but does not show through print information, and has offset printing suitability and ink jet printing suitability such as no bleeding. .

More specifically, when the amount of the sizing agent added is less than 0.01 g / m ² , the size of the base paper is reduced, and the coating liquid to be applied to the surface of the base paper sinks into the base paper. There is a risk of problems such as ink sinking, back-through, and bleeding when printing. On the other hand, when the amount of the sizing agent added exceeds 0.5 g / m ² , the size of the base paper becomes too high, the barrier property of the paper surface is improved too much, and the ink jet ink does not permeate the base paper appropriately. For this reason, the drying property (setting property) of the ink-jet ink is deteriorated, and there is a possibility that the problem of smearing of printing information at the time of high-speed ink-jet printing and the problem of smearing of the ink-jet printer may occur.

[Water-soluble resin coating liquid (composition)]
As described above, in the foam paper of this embodiment, the water-soluble resin coating liquid applied to the surface of the base paper includes at least a paper strength enhancer, an olefin-based sizing agent, and a water-soluble polyamine-based resin.

(Paper strength enhancer)
In this embodiment, the paper strength enhancer is indispensable for preventing white spots during offset printing. Examples of the paper strength enhancer include naturally-occurring polymer compounds such as starch and vegetable gum, urea-formaldehyde resin, polyethyleneimine, melamine-formaldehyde resin, polyamidoamine-epichlorohydrin resin, polyacrylamide resin, and the like. Can be mentioned. However, polyacrylamide resin is used from the viewpoints of coating workability on the surface of lightweight ink jet-compatible foam base paper, compatibility with cationic olefin sizing agents, and ensuring rigidity that enables high-speed full-color inkjet printing. It is preferred to use. Furthermore, cationic polyacrylamide can be suitably used as the polyacrylamide resin. Cationic polyacrylamide is applied to the surface of the base paper in combination with an olefin-based sizing agent, which does not cause generation of foreign matter, discoloration, or thickening, which is a problem in combination with other sizing agents. It has a synergistic effect with excellent coating suitability. In addition, by combining a cationic polyacrylamide and an olefin sizing agent, and further combining a water-soluble polyamine resin and coating on the surface of the base paper, there is no show-through of printing information while being lightweight, and the inkjet ink Form paper that suppresses bleeding and satisfies high-speed form printing suitability, further improves rigidity, reduces curling in full-color inkjet printing, reduces waviness, and has excellent transportability. can get.

  In this embodiment, as the cationic polyacrylamide, one obtained by partially hydrolyzing the amide group in the polyacrylamide, a copolymer of acrylamide and acrylic acid, or the like can be used. In place of the acrylic acid, for example, a copolymer using methacrylic acid or maleic anhydride, or a terpolymer containing acrylonitrile or an acrylate ester as the third component can be used.

  In this embodiment, the average molecular weight of the cationic polyacrylamide is 300,000 to 1,000,000, preferably 400,000 to 500,000. When the average molecular weight of the cationic polyacrylamide is less than 300,000, the rigidity is not sufficiently improved. On the other hand, when it exceeds 1,000,000, the viscosity is increased, the coating operability is lowered, and a problem of mist generation occurs.

  In this embodiment, the cationic polyacrylamide can be suitably used in combination with an olefin-based sizing agent and a water-soluble polyamine-based resin. Further, it is used in combination with various modified starches such as oxidized starch and various polyvinyl alcohols. It can also be used in combination with anionic polyacrylamide.

The coating amount of the paper strength enhancer is preferably 0.5 to 4.0 g / m ² , more preferably from the relationship with the olefin sizing agent and the water-soluble polyamine resin constituting the water-soluble resin coating solution. 0.5 to 3.0 g / m ² . If the coating amount is less than 0.5 g / m ² , the paper strength on the surface of the paper will be insufficient, and there may be a problem of white spots during offset printing. On the other hand, if the coating amount exceeds 4.0 g / m ² , there will be no problem with paper dust during offset printing, but the paper surface will harden and the tear strength in accordance with JIS P 8116 will decrease, resulting in insufficient perforation strength. However, there is a possibility that a problem of paper breakage at the perforation may occur. In addition, if the coating amount of the paper strength enhancer is increased, the barrier property of the paper surface is strengthened too much, and the ink jet ink stays on the paper surface, resulting in poor ink dryness (set property) and printing during high speed ink jet printing. There may be a problem of information stains and ink jet printer stains.

(Olefin sizing agent)
In this embodiment, the olefin-based sizing agent has an effect of preventing bleeding (feathering) of print information during ink jet printing and an effect of preventing print information from being exposed even when the basis weight is low.

The coating amount of the olefin sizing agent is preferably 0.001 to 0.01 g / m ² per side, more preferably one side, considering the synergistic effect of the combination of the paper strength enhancer and the water-soluble polyamine resin. 0.002 to 0.008 g / m ² per unit. If the coating amount is less than 0.001 g / m ² , bleeding of print information during ink jet printing may not be prevented. On the other hand, if the coating amount exceeds 0.01 g / m ² , bleeding at the time of ink jet printing can be prevented, but the barrier property of the paper surface is excessively improved, and the ink jet ink permeates the base paper appropriately. Therefore, the drying property (setting property) is deteriorated, and there is a possibility that the printing information may become dirty particularly during high-speed inkjet printing, or the inkjet printer may become dirty.

  In this respect, in this embodiment, as a sizing agent other than the olefin sizing agent, a styrene resin system, an alkyl dimer system (size pine K-902 manufactured by Arakawa Chemical Co., Ltd.), a higher fatty acid system (NS manufactured by Modern Chemical Industry Co., Ltd.) -815 etc.), surface sizing agents such as petroleum resin (H-7A made by Modern Chemical Co., Ltd.), styrene acrylic synthetic resin (pearl gum CS-25S etc.), etc. can be used. However, an olefin-based sizing agent is preferable from the viewpoint of the solubility with polyacrylamide as a paper strength agent and the synergistic effect with a water-soluble polyamine-based resin.

  In this embodiment, the olefin sizing agent is preferably an olefin sizing agent having cationic properties. Olefinic sizing agents that have cationic properties are self-fixing to the raw material pulp, so a fixing agent is required when applied to the base paper surface together with a paper strength enhancer and a water-soluble polyamine resin. In addition, a water-soluble resin coating layer can be effectively provided on the base paper surface.

(Water-soluble polyamine resin)
In this embodiment, the water-soluble polyamine-based resin has an effect of preventing (water resistance) bleeding when a foam on which ink jet printing has been performed gets wet.

The coating amount of the water-soluble polyamine resin brings about a synergistic effect when combined with a paper strength enhancer and a water-soluble polyamine resin. to satisfy the high-speed jet form printability, preferably per side 0.1 to 1.0 g / m ^2, more preferably per one surface 0.3 to 0.7 g / m ^2. When the coating amount is less than 0.1 g / m ² , the water resistance is insufficient, and the ink-jet printing information is blurred when wet, and the printed content may be unreadable. On the other hand, when the coating amount exceeds 1.0 g / m ² , there is no problem of bleeding of print information when wetted with water, but the manufacturing cost becomes high.

Examples of water-soluble polyamine resins that can be suitably used in this embodiment include (1) polyalkylene polyamines such as polyethylene polyamine and polypropylene polyamine or derivatives thereof, (2) secondary amino groups, and tertiary. Acrylic polymers having amino groups, quaternary ammonium groups, etc., (3) polyvinylamine and polyvinylamidines, (4) dicyan-based cationic polymers represented by dicyandiamide-formalin copolymers, (5) dicyandiamide- Polyamine-based cationic polymer represented by polyethyleneamine copolymer, (6) epichlorohydrin-dimethylamine copolymer, (7) diallyldimethylammonium-SO ₂ polycondensate, (8) diallylamine salt-SO ₂ polycondensation Body, (9) diallyldimethylammonium chlora (10) diallyldimethylammonium chloride-acrylamide copolymer, (11) allylamine salt copolymer, (12) dialkylaminoethyl (meth) acrylate quaternary salt copolymer, (13) acrylamide-diallylamine Examples thereof include a copolymer and (14) a cationic resin having a 5-membered ring amidine structure.

(Auxiliary)
In this embodiment, the water-soluble resin coating liquid may contain, for example, a fluorescent whitening agent in addition to the paper strength enhancer, the olefin sizing agent, and the water-soluble polyamine resin. The fluorescent whitening agent not only has a whitening effect on paper but also has an effect of improving ink acceptability.

  As the fluorescent brightening agent, for example, a stilbene derivative, particularly a stilbene derivative having 5 sulfonic acid groups can be preferably used. The stilbene derivative is generally used as a whitening agent for paper. For example, the whitening effect is improved by using it together with polyvinyl alcohol which is a dyeing substance. In particular, a stilbene derivative having 5 sulfonic acid groups has a further whitening effect. Among them, a stilbene derivative having 5 sulfonic acid groups in a trans form has a high fluorescent whitening intensity and a whitening maintenance period. Is long, which is preferable in terms of further improving the whiteness of the obtained foam paper.

The blending amount of the optical brightener is not particularly limited, but is preferably 0.1 to 2.0 g / m ² per side, more preferably 0.3 per side, from the viewpoint of the whitening effect and cost reduction. ˜1.5 g / m ² . When used in combination with paper strength enhancers, olefin-based sizing agents, and water-soluble polyamine resins, fluorescent whitening agents are used to prevent the generation of inadvertent coagulation in compatible surfaces and water-soluble resin coating solutions. In terms of surface and dispersibility, those having a pH of 8 to 10 and a viscosity of 20 to 40 mPa · s are preferable.

  Furthermore, for example, various auxiliary agents such as a fluorescent whitening agent dyeing substance, an antifoaming agent, a release agent, a colorant, and a water retention agent may be appropriately blended in the water-soluble resin coating liquid of this embodiment. it can.

(Coating / Drying)
The water-soluble resin coating liquid is applied to one or both sides of the base paper, for example, between each dryer part of a dryer part which is usually performed in two stages, that is, a pre-dryer part and an after-dryer part. This is preferably performed in the size press.

  For the application of the water-soluble resin coating solution, for example, a coating device such as a blade coater, an air knife coater, a transfer roll coater, a rod metering size press coater, or a curtain coater can be used. The water-soluble resin coating liquid can be applied to the base paper once or twice or more by the on-machine coater or the off-machine coater provided with the above.

  However, among the various coaters described above, it is preferable to use a roll coater because a homogeneous coating layer is ensured along the waviness of the surface of the base paper.

  Moreover, the drying method in a dryer part is not specifically limited, For example, various heat drying systems, such as hot air heating, gas heater heating, and infrared heater heating, can be employ | adopted suitably.

In this embodiment, the water-soluble resin coating liquid is preferably applied to one or both surfaces of the base paper so as to be 0.6 to 5.0 g / m ² per side. When the coating amount is less than 0.6 g / m ² per side, an uncoated portion is likely to occur on the surface of the base paper, and there is a risk of missing dots or dot defects during ink jet printing. On the other hand, when the coating amount is 0.6 g / m ² or more per side, the surface of the base paper is uniformly coated with a water-soluble resin coating solution, for example, there is no blanket stain in offset printing, It is possible to easily ensure excellent printing aptitude that can be applied to various printing means, such as improving the fineness of printing information during ink jet printing. On the other hand, when the coating amount of the water-soluble resin coating solution exceeds 5.0 g / m ² per side, the absorption drying property of the offset ink or the inkjet ink is inhibited, and the viscosity of the aqueous resin coating solution is reduced. This may increase the productivity and decrease the cost.

Furthermore, the coating amount of the water-soluble resin coating solution is more preferably 1.0 to 3.5 g / m ² , and particularly preferably 2.0 to 3.0 g / m ² . In this range, the excellent printability that can be applied to the above-mentioned various printing means in a multiplicity is further improved.

(Flattening process)
If a water-soluble resin coating solution is applied to one or both surfaces of the base paper, flattening by combining an elastic roll and a metal roll, such as a super calender or soft calender, for the purpose of imparting flatness and printability It is preferable to apply a crystallization treatment. According to the super calendar and soft calendar, unlike the conventional machine calendar, the surface of the paper is processed with a wide surface at a high temperature, so that the density of the base paper and the coating layer is excessively increased. For example, it is possible to form a printing surface suitable for offset 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, and is therefore a software that heats using electricity. Since it is economical compared with a calendar, it is particularly preferably used.

  The linear pressure, temperature, and speed of the calendering process are not particularly limited, but to sufficiently improve the flatness of the coated layer after the treatment and to prevent the final form paper from becoming too tight. In addition, 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 paper passing speed is preferably 500 to 1000 m / min. The Parker print surf roughness can be easily adjusted within a predetermined range described later.

[Form paper]
(Basis weight)
JIS P 8124 form a sheet of the present embodiment, "Paper and board - basis weight measurement method" basis weight that conforms to the, 70 g / m ² or less, preferably 60~70g / m ^2. In line with the trend of resource saving, mail cost reduction, and workability improvement by weight reduction in recent years, printing information does not show through even though it is lightweight, and ink jet ink bleeds even when inadvertently wetted with water Nikuku, in order to satisfy the inkjet printability and offset printability (form printability), in the present embodiment, below a conventional basis weight 80 g / m ² or more forms paper, adjusting the basis weight 60~70g / m ² In addition, a predetermined water-soluble resin coating solution is provided on the surface of the base paper.

More specifically, when the basis weight of the foam paper is less than 60 g / m ² , the tensile strength and tear strength at the time of high-speed form printing become insufficient and the waist is lost, which easily causes printing trouble and conveyance failure. On the other hand, if the basis weight exceeds 70 g / m ² , it goes against the weight reduction of the foam paper.

(ash)
In this embodiment, a filler is internally added to the base paper, and the ash content in accordance with JIS P 8251 is preferably 3 to 12% by mass, more preferably 5 to 10% by mass. This ash content also includes a waste paper-derived filler that is attached to the waste paper pulp used as the raw material pulp and brought into the base paper. When used paper pulp is used as the raw material pulp, the filler adhering to the used paper pulp can be expected to improve the opacity by several percent, but further improvement in opacity and improvement in ink absorption drying in full-color inkjet printing For this purpose, a filler is newly added to adjust the ash content in accordance with JIS P 8251 to 3 to 12% by mass.

  More specifically, to reduce the ash content in accordance with JIS P 8251 to less than 3% by mass, the amount of filler newly added to the base paper is reduced, or fine fibers and ash derived from waste paper are sufficiently washed in the raw material adjustment stage. Although it is possible, there is a possibility that problems such as a decrease in opacity and a decrease in suitability for full-color inkjet printing may occur. On the other hand, when the ash content exceeds 12% by mass, when a full-color ink jet printing machine is used, ink jet printing ink permeation / drying unevenness is likely to occur, and the paper quality easily curls. A more preferable range of ash content measured in accordance with JIS P 8251 is 5 to 10% by mass.

  The type of filler to be newly added is not particularly limited, and for example, known fillers such as talc, clay, titanium dioxide, calcium carbonate and the like can be added. However, it is preferable that 50% by mass or more of the total filler including calcium carbonate-derived filler is calcium carbonate, and more preferably 60 to 90% by mass of the total filler is calcium carbonate.

  In addition, as calcium carbonate, calcite calcium carbonate or aragonite calcium carbonate can be suitably used, and those having a shape such as spindle-shaped or chestnut agglomerated and crystallized calcium carbonate are preferably used. Can do. Lightweight inkjet-compatible foam paper obtained by making spindle-shaped or chestnut-shaped calcium carbonate as a filler, preferably by pH 6-10, more preferably by pH 6.5-9.5 neutral to alkaline. The opacity and stiffness can be improved at the same time.

More specifically, when calcium carbonate is used, the papermaking pH becomes 7 to 9 due to the buffer effect of calcium carbonate. When the papermaking pH is neutral or alkaline, the pulp fiber 1 is compared with the case where the papermaking pH is acidic. Since one book extends sufficiently, the area where the fibers form hydrogen bonds increases. Therefore, when the ash content is about the same as that of acidic printing paper, the paper strength of neutral printing paper is higher. As a result, even if the basis weight is 70 g / m ² or less and lightweight inkjet-compatible foam paper is used. In addition, a decrease in Clark stiffness is suppressed, excellent transportability in a printing press, and sufficient strength to withstand high-speed rotary printing can be obtained. In addition, calcium carbonate, for example, has a lower proportion of waste paper pulp as a waste paper-derived filler than white carbon, but has a cationic olefinic sizing agent or a cationic water-soluble polyamine resin. This contributes to improving the chemical yield of the olefin sizing agent having a cationic property, and the effect of blending the olefin sizing agent is improved.

  Furthermore, the printability of lightweight inkjet-compatible foam paper using spindle-type or chestnut-like calcium carbonate as a filler is, for example, compared to conventional foam paper containing columnar, cubic, or needle-like light calcium carbonate. Very good and whiteness is high. In addition, when spindle-shaped or chestnut-shaped calcium carbonate is used, ink for ink-jet printing is likely to adhere to the paper surface, and it becomes difficult to cause stains on the printing press and printing surface due to unfixed ink.

  Spindle-type or chestnut-like calcium carbonate is obtained by reacting calcium hydroxide with a gas containing carbon dioxide, for example, calcium carbonate having a spindle-type or columnar stable calcite-type crystal structure or calcium carbonate having a metastable aragonite-type crystal structure. In the process of obtaining the carbon dioxide-containing gas, the spindle type can be adjusted by adding an additive such as condensed phosphoric acid or a metal salt thereof when adjusting the method of supplying the carbon dioxide-containing gas or performing dehydration, drying, or heat treatment. Since the columnar crystal structure aggregates or crystallizes in a chestnut shape, it can be obtained by utilizing this phenomenon.

(Surface roughness)
The form paper of this form is a Parker print measured according to the method described in ISO 8791-4 “Paper and paperboard—Roughness smoothness test method (air leakage method) —Part 4: Print Surf method”. It is preferable that the surf roughness is 1.50 μm / Pa · s or more, further 1.70 μm / Pa · s or more, particularly 1.80 μm / Pa · s or more, both on the front surface and the back surface. It is preferably not more than .50 μm / Pa · s, more preferably not more than 3.30 μm / Pa · s, particularly preferably not more than 3.20 μm / Pa · s.

  For example, when performing offset full-color printing and full-color inkjet printing, Beck smoothness, Oken-style smoothness, and optical smoothness measurement can be used as an index of printability in individual printing means. There are merits and demerits in grasping the printing suitability adapted to multi printing for various types of printing. Therefore, in this embodiment, 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 becomes difficult to obtain a high-definition and excellent dry surface in ink jet recording. There is a fear. On the other hand, if 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 print surface can be obtained in offset full-color printing and full-color inkjet printing. May be 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, more preferably 0.98 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, it is possible to obtain a foam paper that is lightweight and more suitable for any of various printing methods such as offset full-color printing and full-color inkjet printing.

  In this specification, the Parker Print Surf roughness is based on the above-mentioned ISO 8791-4, and the Parker Print Surf (PPS) surface smoothness tester (model name: MODEL M-569 type, 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.

  In the preparation of the surface roughness, in this embodiment, since the surface of the base paper is coated with a water-soluble resin composition combining at least a paper strength enhancer, an olefin-based sizing agent, and a water-soluble polyamine-based resin, For example, with a super calender as described above, the linear pressure is 95 to 300 kN / m, the metal roll temperature is 50 to 90 ° C., and the speed is 500 to 1000 m / min. As is done, the paper surface can be kept flat with little wrinkle return, and it is lightweight, but there is no print information leakage, and in addition to offset printing suitability, ink jet printing suitability such as no bleeding occurs. Can be obtained.

(Dynamic friction coefficient)
The foam paper of the present embodiment is coated with a water-soluble resin composition combining at least a paper strength enhancer, an olefin-based sizing agent, and a water-soluble polyamine resin on the surface of the base paper, whereby JIS P 8147 “paper and In accordance with the method described in “Method for testing coefficient of friction of paperboard”, the coefficient of dynamic friction measured in a standard state in accordance with JIS P 8111 “Paper, paperboard and pulp—standard state for humidity conditioning and testing” It can be suitably adjusted to 50-0.90. If the coefficient of dynamic friction is less than 0.50, the papers are slippery, and in full color inkjet printing, for example, the paper may slide on the roll during printing and registration misalignment may occur. On the other hand, if the dynamic friction coefficient exceeds 0.90, the frictional force applied between the papers is large, so that the surface of the paper is easily damaged, and the glossiness, smoothness, and printability that can be printed in various types may be reduced. .

  The dynamic friction coefficient is further preferably 0.55 or more, particularly preferably 0.60 or more, more preferably 0.85 or less, and 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 this embodiment, the transportability in full-color ink jet printing is extremely important. In order to achieve a good balance between transportability and printability on a lightweight foam paper of 70 g / m ² or less, the dynamic friction coefficient is For example, by adjusting the content of calcium carbonate so as to be within the range, or by performing a flattening treatment as described above, the obtained form paper is given a surface property adapted to any of various printing methods. It is preferable.

  In this specification, the coefficient of dynamic friction is based on the horizontal method of JIS P 8147, and a blank inkjet form sheet is attached to both the horizontal plate and the weight, and the front and back surfaces of these inkjet form sheets are opposed to each other. The values measured in a standard state in accordance with JIS P 8111 with the tensile speed being 200 mm / min and the front and back surfaces being rubbed by measurement in the front-back and longitudinal-vertical directions.

  The dynamic friction coefficient can also be adjusted by, for example, the super calender described above, by flattening at a linear pressure of 95 to 300 kN / m, a metal roll temperature of 50 to 90 ° C., and a speed of 500 to 1000 m / min. .

  The dynamic friction coefficient is also influenced by the raw material pulp that constitutes the base paper, and is composed of raw pulp made by combining recycled pulp with main components of hardwood kraft pulp that is suitable for this embodiment. Is preferably 70 to 95: 5 to 30, more preferably 75 to 95: 5 to 25, and furthermore, the hardwood kraft pulp used as the main component has a CSF of 400 to 550 mL, particularly 450 to 500 mL. It is preferable to do.

  By setting the ratio of hardwood kraft pulp in the raw material pulp to 70-95%, a water-soluble composition comprising a combination of a paper strength enhancer, an olefin sizing agent, and a water-soluble polyamine resin is excessively penetrated into the base paper. It is possible to apply the coating on the surface of the base paper without making it, and it is possible to improve the flatness of the surface of the paper and to adjust the coefficient of dynamic friction low. In addition, by containing 5-30% of waste paper pulp that is relatively flatter than virgin pulp, the gap on the surface of the base paper is reduced, and a paper strength enhancer, an olefin-based sizing agent, and a water-soluble polyamine-based resin are formed on the surface of the base paper. Since the water-soluble composition comprising the combination can be applied uniformly, unevenness is reduced, and the dynamic friction coefficient can be easily adjusted by the flattening means.

(Moisture permeability)
The foam paper of this embodiment is coated with a water-soluble resin composition in which at least a paper strength enhancer, an olefin-based sizing agent, and a water-soluble polyamine resin are combined on the surface of the base paper, so that JIS Z 0208 “Moisture-proof packaging” The moisture permeability M20 at a temperature of 20 ° C. and a relative humidity of 65% is 500 g / m ² · 24 h or less and the temperature is 40 ° C. according to JIS Z 0208. The moisture permeability M40 at a relative humidity of 65% can be adjusted to 1000 g / m ² · 24h or more.

When M20 exceeds 500 g / m ² · 24 h, moisture is absorbed and released at room temperature, and the paper is likely to be wrinkled and waved, and distortion is likely to occur, which may reduce dimensional stability. In addition, when M40 is less than 1000 g / m ² · 24 h, for example, in full-color inkjet printing, in order to fix and dry the inkjet printing ink on the paper, it is difficult for the solvent contained in the ink to escape to the outside of the paper. There is a risk of wrinkles, waves, and distortion.

The above moisture permeability, M20 is 200g / m ² · 24h or more, or less 480g / m ² · 24h, and, M40 is 1100g / m ² · 24h or more, preferably more is not more than 1750g / m ² · 24h .

  The inventors' knowledge has been found as a configuration for providing foam paper that is lightweight but does not show through print information, suppresses bleeding of inkjet ink, and satisfies inkjet printability even when high-speed form printing is performed. Furthermore, by applying a water-soluble composition combining at least a paper strength enhancer, an olefin-based sizing agent, and a water-soluble polyamine resin on the surface of the base paper, and by limiting the moisture permeability, high-speed form printing Improves wrinkles and wave distortion of the paper at the time.

  Further, in this embodiment, by adjusting both the moisture permeability M20 and moisture permeability M40 to the above values, not only the above-mentioned problems can be solved, but also excellent dimensional stability and printability as an inkjet-compatible foam paper. Furthermore, a sufficiently satisfactory quality can be ensured.

  In this specification, the moisture permeability M20 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 apparatus 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 M40 is based on the cup method of JIS Z 0208, and contains about 20 g of water containing 0.5% by weight of a polyacrylate highly water-absorbent resin 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 embodiment, not only the surface roughness of the paper but also the surface property of the dynamic form paper is adjusted, and the dynamic friction coefficient on the front and back surfaces of the foam paper is appropriately adjusted. It is possible to obtain a foam paper that not only has a better form printability and dimensional stability, but is also particularly excellent in paper transportability and inkjet full-color printability.

(Print opacity)
The form paper of this embodiment has a printing opacity of 80 to 90% (preferably 82 to 88%) in accordance with JIS P 8149. When the printing opacity is less than 80%, it becomes easy to read the printed content from the reverse side. On the other hand, if the printing opacity exceeds 90%, there is no problem from the viewpoint of printing opacity, but in order to obtain a printing opacity exceeding 90%, it is necessary to contain in a portion exceeding 12% of the ash content in the base paper Therefore, it is difficult to obtain foam paper that satisfies the suitability for inkjet printing even if it is lightweight and does not show through print information, suppresses bleeding of inkjet ink, and performs high-speed form printing.

(Whiteness)
In order to further improve the appearance of the foam paper of this embodiment, the whiteness of the paper measured in accordance with JIS P 8148 “Paper, Paperboard and Pulp—Method for Measuring ISO Whiteness (Diffusion Blue Light Reflectance)” is 70. % Or more, more preferably 75% or more. Compared to a case where the whiteness is less than 70%, for example, a photographic finish specific to various full-color printings with higher definition and higher contrast can be obtained. Such whiteness of the foam paper can be achieved by adjusting the raw material pulp composition, papermaking conditions, and coating pigment.

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.
A paper strength enhancer, a sizing agent, and a water-soluble polyamine resin adjusted to have the coating amount shown in Table 2 using the raw material pulp, the internally added sizing agent, and the filler described in Table 1 as papermaking raw materials. Foam paper was manufactured using the coating liquid containing, using a papermaking system including a wire part, a press part, a pre-dryer part, a size press, an after-dryer part, a calendar part, a reel part, and a winder part. A hybrid former was used for the wire part, a gate roll was used for the size press, and a soft calendar was used for the calendar part. In this case, “mass%” means solid content unless otherwise specified, and “coating amount” is per one side. The details of the chemicals used are shown below.

(Internal sizing agent)
AKD (alkyl ketene dimer): Size Pine K-78 manufactured by Arakawa Chemical
(Internal PAM)
-PAM (polyacrylamide): DS4366 made by Seiko PMC
(External paper strength enhancer)
Cationic PAM (polyacrylamide): ST5000 made by Starlight PMC, molecular weight was adjusted based on ST5000.
・ Oxidized starch: MS3800 manufactured by Nippon Shokuhin Kako Co., Ltd.
(External additive sizing agent)
・ Olefin system: SS2920 manufactured by Seiko PMC
・ Styrene: SS2720 manufactured by Seiko PMC
-AKD: SE2360 manufactured by Seiko PMC
(Externally added water-soluble polyamine)
・ Nittobo Polyallylamine PAA-03
(Filler)
・ Calcium carbonate: Tama Pearl TP-121-6S manufactured by Okutama Kogyo Co., Ltd.
・ Clay: ANSHILEX93 manufactured by ENGELHARD
・ Talc: Talc made by Nippon Talc

  The obtained foam paper was examined for various qualities, and the results are shown in Tables 3 and 4. Various quality measurement / evaluation methods are as follows.

[Basis weight (US tsubo)]
The measurement was performed according to the method described in JIS P 8124 “Paper and paperboard—basis weight measurement method”.

[PPS smoothness]
Parker Print Surf (PPS) surface smoothness tester 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" (Model name: MODEL M-569 type, manufactured by MESSMER BUCHEL) was used, and the measurement was performed under the condition that the backing disk was a soft rubber and the clamp pressure was 1 MPa.

[Paper thickness]
Measured according to JIS P 8118 “Paper and paperboard—Test method for thickness and density”.

[Stiffness (Horizontal)]
In accordance with JIS P 8143 “Paper Clark Stiffness Test Method”, the paper width direction (horizontal) value was measured.

[Printing opacity]
Measured according to JIS P 8149 “Paper and paperboard—Opacity test method (paper backing)”.

(Dynamic friction coefficient)
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 placed facing each other. Standard condition according to JIS P 8111 “Standard condition for paper conditioning and testing” with front and back surfaces rubbed at 200 mm / min. Measured with

[Whiteness]
It was measured according to the method described in JIS P 8148 “Paper, paperboard and pulp—Method for measuring ISO whiteness (diffuse blue light reflectance)”.

[Offset printing aptitude]
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 4 colors on the surface of the 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 1 or less, 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: There are 4 or more white spots, and the printability is very poor.
Of the above evaluation criteria, the cases of ○ and ○ are judged to be actually usable.

[Inkjet printing suitability (IJ 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.

[Transportability]
In the inkjet printing when evaluating the inkjet printing suitability, the number of occurrences 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.

(Dimensional stability)
The printed surface of the printed matter obtained when the offset printability and the inkjet printability were evaluated was visually observed and evaluated based on the following evaluation criteria.
(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: Wavy, wrinkled, and distortion is remarkable.
Of the above evaluation criteria, the cases of ○ and ○ are judged to be actually usable.

[(Inkjet printing) back-through]
It was confirmed how much the printed information of the printed matter obtained when the inkjet printing suitability was evaluated was read when viewed from the opposite side.
A: There is no strikethrough.
○: There is some showthrough and the printed content can be read slightly.
(Triangle | delta): There exists a back-through and the printed content can be read and may become a problem practically.
X: The show-through is remarkable and cannot be used practically.
Of the above evaluation criteria, the cases of ○ and ○ are judged to be actually usable.

[Bleeding by water]
The printed matter obtained when ink jet printing suitability was evaluated was soaked in water for 10 seconds, and it was confirmed whether the printed content oozed.
A: There is almost no bleeding.
○: There is some bleeding, but the printed content can be read.
(Triangle | delta): There exists a place which has bleeding and cannot read the printed content.
X: The bleeding is remarkable and the printed content cannot be read.
Of the above evaluation criteria, the cases of ○ and ○ are judged to be actually usable.

[Drying]
The printed matter obtained when ink jet printing suitability was evaluated was rubbed with a tissue 3 seconds after printing to confirm whether the ink was smeared.
A: There is almost no ink fading.
○: The ink content is slightly blurred but the printed content can be read.
(Triangle | delta): There are many blurs of ink and there exists a part which cannot read print content.
X: The ink is very faint and the printed content cannot be read.

  In all the foam papers of the examples, a predetermined aqueous composition (water-soluble resin coating solution) is applied to form a coating layer, and the basis weight is adjusted to a specific range. Therefore, the form paper of the examples is excellent in both offset printing suitability and ink jet printing suitability, and is also excellent in paper transportability and dimensional stability, and has characteristics suitable for all forms printing. is there.

  On the other hand, the foam paper of the comparative example is inferior to any of offset printability, inkjet printability, and printability because the composition and basis weight of the aqueous composition are not specified as in the above examples. It is difficult to say that it has suitable characteristics for all forms printing.

  Similarly, the current commercial product A, the current commercial product B, and the current commercial product C of the reference example are not specified as in the above examples, because the composition and basis weight of the aqueous composition are not specified. It is inferior to either ink-jet printing suitability or print suitability, and it is difficult to say that it has suitable characteristics for all forms printing.

  The foam paper of the present invention is applicable as a foam paper suitable for any of various forms printing such as inkjet printing and offset printing.

Claims (4)

A foam paper in which a water-soluble resin coating liquid is coated on at least one side of a base paper containing raw pulp and filler,
The basis weight according to JIS P 8124 is 70 g / m ² or less,
The coating liquid contains at least a paper strength enhancer, an olefin sizing agent, and a water-soluble polyamine resin.
Form paper characterized by that. The coating amount per one side 0.001 to 0.01 g / m ² of the olefinic sizing agent, coating amount of the water-soluble polyamine resin is a single-sided per 0.1 to 1.0 g / m ² ,
The foam paper according to claim 1. More than 50% of the filler is calcium carbonate,
The filler containing calcium carbonate is blended 3 to 12% in the base paper,
The opacity according to JIS P 8149 is 80 to 90%,
The foam paper according to claim 1 or 2. The coating amount of the paper strength enhancer is 0.5 to 4.0 g / m ² per side,
The foam paper of any one of Claims 1-3.