JPH0921092A - Printing paper and its production - Google Patents

Abstract

PURPOSE: To obtain printing paper excellent in formation, not damaging strength and physical properties, having improved opacity, high smoothness and excellent in surface strength and ink impression. CONSTITUTION: A polyamide resin is dissolved in a solvent of a metal salt- organic solvent. One or more selected from the organic solvent, another organic solvent uniformly mixable with the organic solvent and water are added to the solution to precipitate white opaque polyamide resin particles, which are washed with water to give porous amorphous polyamide resin particles. At least one side of a substrate base paper constituted of a material containing 2-20wt.% of the porous amorphous polyamide resin particles is coated with a clear sizing coating material in an amount of 0.2-2.0g/m<2> and calendered to give objective printing paper having 2-5μm parker print surface roughness (ISO8792).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a printing paper and a manufacturing method thereof. Specifically, a printing paper having a clear size coating layer provided on the surface of a base paper for a support, which has a good texture of the paper, good physical strength characteristics and opacity, and is suitable for offset printing or gravure printing, and a method for producing the same. Regarding

[0002]

2. Description of the Related Art In recent years, with the wave of product differentiation and high quality, multi-color printing of commercial printing such as catalogs and leaflets has progressed rapidly, and direct mail paper, etc. can be used with low postage. In order to convey a large amount of information, there is a demand for thinner sheets and papers having a better printing effect. It is necessary to design the printing paper for these uses in a well-balanced manner to meet various needs such as workability of offset printing, excellent printing surface quality, light weight and high opacity.

In the "Production Method of Porous Polyamide Powder" of JP-A-52-14668, the porous polyamide powder has extremely preferable properties as an adsorbent, and the most useful application is a vegetable drink. It is described as the adsorption removal of polyphenols therein. At that time, the shape of the polyamide powder is important, it is porous according to the electron micrograph, and since the surface has numerous pores, the surface area per unit weight is large. Have been described. As one method of adsorption and removal of polyphenols by this porous polyamide powder, the porous polyamide powder is mixed and dispersed with bleached sulfite pulp, paper-made with a handmade paper machine, and dried at 103 ° C. for 3 hours. It is described that a filter paper-like sheet was produced.

In "Development and application of high-performance paper" (CMC, 1988), filter paper refers to fine particles in a fluid (liquid or gas) on fibers (surface filtration) or between fibers (internal filtration). ), There are many voids so that the fluid can pass through easily. By adjusting the physical properties of the fibers that make up the sheet, squeezing, the thickness of the sheet, etc., filter paper of various retained particle sizes can be made. There is a description. Especially beer,
An internal filtration type filter of 3 to 5 mm is used for finish filtration of beverages such as whiskey, wine, sake, etc. In the case of manufacturing a filter plate whose main purpose is internal filtration, suction suction dehydration at the time of papermaking is strongly performed and compressed. As described in the above, it is said that very light and gentle drying is carried out, and in the manufacture of filter paper, there is usually no calender treatment after drying.

Therefore, in the preparation of the filter paper-like sheet in which the porous polyamide powder is added as described above, there is no description of calendering treatment therein, and the porous polyamide powder in the filter paper-like sheet is not described. There is no description about the shape. Even if it is calendered, the porous polyamide powder is crushed, its surface area is reduced, and the adsorption efficiency of polyphenols is reduced, so it is not suitable for the purpose as a filter paper.

[0006] Such a filter paper-like sheet which is not subjected to calendaring has a rough surface and poor surface strength, so that the printing surface quality is poor and it is not suitable for printing applications.

In general, a so-called uncoated paper in which a coating layer containing an inorganic or organic filler is not provided on a support base paper, is surface-treated by a calender device such as a machine calender or a super calender in order to improve the printing surface quality. Is being done. Although it is possible to improve glossiness and smoothness by these treatments, on the other hand, when the surface treatment is performed under strong treatment conditions, the pulp fibers constituting the support base paper are broken, and the binding and entanglement between pulp fibers are Since the fibers on the surface of the support base paper are damaged by the destruction, the surface strength is lowered, and the paper may be peeled off when printed by an offset printing machine or adhered or deposited on the blanket of the printing machine to improve the printing surface quality. There was a problem of damage.

In order to improve the surface strength of the support base paper, polyvinyl alcohol, starch, polyvinyl acetate can be applied with a coating machine such as a double roll size press, a gate roll coater, a bill blade coater or a short dwell blade coater. It is generally practiced to apply a size coating solution such as a styrene-butadiene copolymer.

However, when these size coating solutions are applied, it is often difficult to improve the glossiness and smoothness and the surface strength is improved, but the surface strength tends to decrease as the calendering treatment is strengthened. There is no difference in that. In addition, if a large amount of these size coating liquids is applied, the opacity and tensile strength will decrease, so
The purpose cannot be achieved only by applying the size application liquid.

On the other hand, as a method for improving glossiness and smoothness in the base paper for support subjected to calendering, talc, clay, calcium carbonate, inorganic filler such as hydrous silicate, urea formalin resin, polystyrene and the like are synthesized. It is possible to improve glossiness and smoothness even under the same calendering conditions by internally adding an organic filler made of resin to paper, but on the other hand, these fillers have a weak binding force with pulp fiber. Therefore, there is a problem that the tensile strength, tear strength, and surface strength during printing of paper are significantly reduced.

Therefore, in the combined use system of the fillers, the paper is suitable for offset printing such as increasing the opacity without impairing the strength of the paper, further improving the surface strength when wet, and improving the ink inking property and the strike-through. Development of internal additives was desired.

[0012]

DISCLOSURE OF THE INVENTION According to the present invention, a clear size coating layer is provided on a support base paper without providing a coating layer containing a filler on the support base paper. An object of the present invention is to provide a printing paper which is improved and is excellent in offset printing suitability or gravure printing suitability. Another object of the present invention is to provide a method for manufacturing such printing paper.

[0013]

[Means for Solving the Problems] As a result of intensive research to solve the above problems, after dissolving a polyamide resin in a metal salt-organic solvent solvent in a raw material mainly composed of pulp and filler, The organic solvent, the other organic solvent which is uniformly mixed with the previous organic solvent, and one or more selected from water to precipitate the white opaque polyamide resin particles, which are further washed with water to obtain a metal salt and an organic solvent. By applying 0.2 to ² g / m ^{2 of} clear-size paint on at least one side of a base support paper composed of a raw material containing 2 to 20% by weight of porous polyamide resin particles produced by removing According to the present invention, it was found that a printing paper having good strength characteristics and optical characteristics, improved smoothness, and excellent offset printing suitability was obtained, and the present invention was accomplished.

In the method for producing polyamide resin particles according to the present invention, a polyamide resin as a raw material is dissolved in a solvent of metal salt-organic solvent, and then the solution is uniformly mixed with the above organic solvent and the above organic solvent. Characterized in that the white opaque polyamide resin particles are precipitated by adding one or more selected from other organic solvents and water, and further washed with water to remove the metal salt and the organic solvent. When the polyamide resin particles thus obtained are added to the pulp slurry, it is desirable that the polyamide resin particles be in the form of a water-dispersed slurry, but they may be in a dry state in preparation for storage and transportation.

Polyamide resin, which is generally called nylon, is widely used as plastic moldings and films including fibers. As the raw material of the polyamide resin particles used in the present invention, nylon 6, such as nylon 6, nylon 66, nylon 610, nylon 612, nylon 11, nylon 12, nylon 46, etc., or a combination of two or more of these nylons, is used. It may be a polymer or a mixture thereof. Not only unmolded resin, but also waste such as fiber scraps produced during the molding process and defective molded products can be used as raw materials. Nylon as a raw material can be used even if it is a transparent body, and even if the polyamide resin particles obtained by the production method of the present invention do not become a white opaque body, it is used by uniformly mixing and dissolving with other nylons. Sometimes, as a result, the polyamide resin becomes a white opaque body. Further, the weight average molecular weight of nylon as a raw material is not particularly limited.

Next, a method for producing polyamide resin particles will be described. Polyamide resin particles have great industrial value as a raw material for powder coatings, adsorbents, cosmetic bases, sintered molded products, etc., and various production methods have been proposed.
Polymerization method to obtain a polymer having a desired particle size from a monomer, mechanical pulverization method using a resin as a raw material, pulverization method using a nozzle as a raw material to discharge resin, and a method for obtaining fine particles by a chemical prescription using a resin as a raw material However, since the shape, size, particle diameter, etc. of the polyamide resin particles obtained by the manufacturing method are different, they are manufactured according to the purpose. Most of the shapes of the polyamide resin particles obtained by the above-mentioned production method are spherical or lump particles close to a sphere. For example, in a cosmetic base, a particle diameter of 20 μm or less, and a sphere or a shape close to a sphere is preferred. It is used. The mechanical pulverization method can obtain an amorphous particle, but the particle size is 100 μm or more and 20 μm or less cannot be obtained. Even if the polyamide resin particles produced by the above-mentioned conventional production method are mixed with pulp slurry for papermaking, the strength of the obtained paper is not improved, and many of them also reduce the whiteness of the paper.

The polyamide resin particles produced according to the present invention are white or cloudy and opaque and are produced as follows.

First, after dissolving the metal salt in the organic solvent A,
Polyamide resin as a raw material is added, and sufficiently stirred at room temperature to disperse or swell, and then dissolved to obtain an organic solvent A, the above-mentioned organic solvent and water which are uniformly mixed with the organic solvent A. One or more of them are added to precipitate the polyamide resin particles. Then, it is washed with a large amount of water, the supernatant liquid is removed, and the washing is repeated with water until the metal salt and the organic solvent are removed to obtain a slurry of white opaque polyamide resin particles. This particle is a porous amorphous particle.

The polyamide resin particle slurry is a water suspension of polyamide resin particles and is uniformly dispersed in water without adding a dispersant, so that it can be mixed with the pulp slurry as it is and stirred for papermaking. The particle size of polyamide resin particles used as an additive for papermaking can be controlled in a timely step of producing particles or in a screen step as a post step, depending on the purpose of the paper to be used. When used in a normal papermaking process, the polyamide resin particles have an average particle size of 3 to 20 μm and a particle size distribution of 70% or more of 1 to 30 μm from the viewpoint of the yield and the effect of improving the strength of the paper.
It is preferred that Further, the obtained polyamide resin particle slurry may be filtered once and dried, and in this case, a polyamide resin having a desired particle diameter is obtained by pulverizing and sieving in water using a pulverizer such as a mixer. A particle slurry can be obtained, which can be similarly mixed and stirred with pulp slurry for papermaking.

In addition, in the step of dissolving the polyamide resin, it is desirable to heat in order to improve the dissolving efficiency. In this case, the precipitation step is preferably performed after returning to room temperature.

The specific gravity of polyamide resin is 1.14 for nylon 6 and nylon 66, and 1.09 for nylon 610.
It is very light, is equivalent to the specific gravity of water, and is slightly lighter than the specific gravity of pulp (1.45 in LBKP). Further, although the polyamide resin particles are not dissolved in water, they have hygroscopicity and high hydration power, so that aggregation of the polyamide resin particles is unlikely to occur. The polyamide resin particles obtained by the above-mentioned production method are porous amorphous particles, and since they have a slow sedimentation speed, they can be uniformly dispersed in water and can be uniformly dispersed with pulp in the pulp slurry.

The concentration of the polyamide resin is equal to or lower than the concentration at which it is uniformly dissolved in the solvent of organic solvent-metal salt, preferably 0.5 to 15% by weight. More preferably, it is 1 to 5% by weight.

The above organic solvent is capable of dissolving the metal salt described below, and also capable of dissolving the polyamide resin in a mixed system with the metal salt, and further, it is possible to dissolve active protons which cause decomposition of the polymer. It does not have to have it. Examples thereof include alcohols, lactams, amide compounds, urea compounds, imide compounds and ether compounds. Of these, preferred are methanol, ethanol, benzyl alcohol and N-methylpyrrolidone from the viewpoint of the solubility of nylon. , N, N-dimethylacetamide, N, N-dimethylformamide, dimethylsulfoxide, γ-butyrolactam, and more preferably methanol.

Metal salts are represented by IA, IIA,
Included are Group IIB halogenated salts, perhalogenates and thiocyanates, of which lithium, calcium, magnesium, zinc halides or perhalates, and lithium, sodium, potassium, calcium thiocyanates. Acid salts are preferred, with calcium chloride being most preferred. Further, the amount of the salt added may be equal to or less than the saturation amount that dissolves in the organic solvent, and preferably 20 to
It is 50% by weight, more preferably 30-40% by weight.

If necessary, various papermaking additives may be mixed in the polyamide resin particle slurry as long as they do not impair the addition effect of the polyamide resin particles.
For example, water-soluble polymer compounds such as starch, polyacrylamide, polyvinyl alcohol, polyethyleneimine, and polyethylene oxide, and modified products thereof, styrene / acrylic copolymers, styrene / maleic acid copolymers, melamine resins, urea resins, etc. And the modified products thereof.

Next, the method for producing the printing paper according to the present invention is as follows.
The polyamide resin particles obtained by the above method were added to a slurry mainly composed of pulp and a filler to uniformly disperse the stock material, and the clear stock was prepared on a base paper for support prepared by a conventional method. It is characterized by applying a paint and calendering. It should be noted that it is desirable to adjust the paper stock by adding polyamide resin particles to the pulp slurry and then adding a cationic or amphoteric retention aid. The polyamide resin particles have an average particle size of 3 to 20 μm, 70
It is desirable that the particle size distribution of 1% to 30 μm is adjusted.

The pulp used in the present invention includes unbleached or bleached kraft pulp (KP) of softwood (N material) and hardwood (L material), sulfite pulp (SP),
Semi-chemical pulp (SCP), Chemiground pulp (CG
P), thermomechanical pulp (TMP), refiner ground pulp (RGP), ground pulp (G
P), pulp such as deinked waste paper pulp (DIP) is used. These pulps are variously selected according to the required physical properties of the paper type to be made, and used in combination.

The support base paper used in the present invention is prepared by blending the above-mentioned pulp and adding polyamide resin particles to the pulp slurry using a conventionally known paper machine, and inorganic fillers such as talc, calcium carbonate, clay and hydrous silicate. , Organic filler made of synthetic resin such as urea formalin resin, polystyrene, etc. Add organic filler, and if necessary, sulfuric acid band, sizing agent, paper strengthening agent, retention aid, pigment, colorant, fluorescent dye, quenching agent A foaming agent and other chemicals for papermaking are added to produce paper as acid paper or neutral paper.

The support base paper containing the polyamide resin particles, which is produced by the above-described paper making method, has a better texture than the support base paper containing no polyamide resin particles. The content of the polyamide resin in the support base paper is 2 to 20% by weight, more preferably 4 to 10% by weight, based on the pulp in the dried paper. If the content is less than 2%, a sufficient paper-strengthening effect and ink receptivity during printing cannot be obtained, and if it is more than 20%, the stiffness of the paper tends to be weak.

The basis weight is about 20 to 100 g / m ² , preferably about 30 to 80 g / m ² . If the basis weight is too small, the strength of the paper will decrease, and if it is too large, sufficient strength will be obtained regardless of the addition of polyamide resin particles.

A clear-size coating layer is further provided on the support base paper, and this coating layer comprises starch, oxidized starch, esterified starch, etherified starch,
Cationized starch, modified starch such as enzyme modified starch, cellulose derivative such as carboxymethyl cellulose, hydroxyethyl cellulose, methyl cellulose, polyvinyl alcohol, carboxy modified polyvinyl alcohol, styrene-maleic anhydride copolymer, styrene-acrylic copolymer, styrene-butadiene It is applied in the state of an aqueous solution containing a binder selected from a copolymer, polyvinyl acetate, a vinyl chloride-vinyl acetate copolymer, polyvinyl chloride, polyvinylidene chloride, polyacrylic acid ester, or an aqueous latex.

The coating amount is 0.2 to ² g / m ² on at least one side of the support base paper. When it is applied to both sides of the paper, it is necessary to apply each to 0.2 to ² g / m ² , preferably 0.3 to ^2.
It is applied in the range of 1.5 g / m ² .

If desired, various additives such as a dispersant, a flow modifier, a dye, an antifoaming agent, a lubricant, a water-proofing agent and a cross-linking agent may be appropriately added to the clear size coating solution.

The clear-size coating liquid is a conventionally known two-roll size press, air knife coater, roll coater, gate roll coater, blade coater, or various coating equipment such as bill blade, twin blade, short dwell blade. Applied on-machine or off-machine.

It is necessary to treat the clear size coated paper with a calender such as a machine calender or a super calender according to various printing qualities to treat the coated surface. Usually, a machine calender is used to obtain a desired paper thickness, smoothness, Treated with a nip pressure so as to give a glossy paper, preferably 10 to
120 kg / cm, and more preferably 30 to 10
It is 0 kg / cm. The support base paper calendered with such a nip pressure has improved smoothness, and a printing paper having Parker print surf roughness in the range of 2 to 5 μm can be obtained.

Further, in the clear-size coated paper using LBKP or LBKP as the main pulp,
By the calendar treatment, a paper having a Parker print surf porosity of 100 to 500 ml is obtained.

In particular, when it is desired to impart gloss to the paper, it is further processed with a super calender at a nip pressure so as to obtain a desired gloss level. The nip pressure of the super calendar is preferably 120 to 300 kg / cm, more preferably 180 to 250 kg / cm.

The glossiness and smoothness are further improved by using a heated calender roll during calendering. The calender roll temperature is preferably 20 to 100 ° C, more preferably 30 to 80 ° C.

Further, in order to obtain whiteness, opacity, smoothness, surface strength and glossiness, pulp blending, filler blending, clear size blending and calendering conditions can be appropriately changed according to quality design.

The paper containing the polyamide resin particles produced by the above method, coated with a clear size, and calendered has a slightly higher density than the paper containing no polyamide resin particles, and has a higher tensile strength and burst strength. The strength such as folding endurance is improved. Further, smoothness and air permeability are also improved.
The reason for this is that when observed with an electron micrograph, the polyamide resin particles are present between the pulp fibers constituting the support base paper or in the gaps, and the polyamide resin particles are crushed by the calendering process to form an amoeba-like shape, and thus per unit area. It was found that the voids in the fiber became smaller and the interfiber bonding strength increased.

In addition, since the polyamide resin particles are porous and white and opaque, the optical properties such as whiteness and opacity are improved, and the ink receptivity during printing is improved.

Further, in the present invention, in consideration of the yield of polyamide resin particles, it is desirable to additionally use a cationic or amphoteric retention aid. The order of addition to the pulp slurry may be either first or simultaneously. First, the polyamide resin particles are mixed with the pulp slurry and stirred, and then the cationized polyacrylamide resin and the cationized polyacrylamide resin are added. By adding a yield improving agent such as starch, the yield of polyamide resin particles is improved, and the strength of the produced polyamide resin particle-containing paper is further improved.

As the retention aid, a cationic polyacrylamide resin, an amphoteric resin, polyethyleneimine or a derivative thereof, a cationic or amphoteric starch and the like are used.

The cationic functional group in the cationic polymer is 3 to 15 mol%, the cationic functional group in the amphoteric polymer is 5 to 35 mol%, and the anionic functional group is 3 to 15 mol%. The functional group mol% is
In the (co) polymer, it represents the percentage of the number of moles of the monomer unit to which the functional group is bonded with respect to the total number of moles of the monomer unit.

The amount of retention agent added is usually 0.1 to 5.0% by weight, preferably 0.3 to 2.0% by weight, for cationized starch, and 50 for cationized polyacrylamide, based on the pulp. ~ 500 ppm, preferably 1
It is from 00 to 300 ppm.

[0046]

It is said that the strength of paper is closely related to the number of hydrogen bonds generated between pulp fibers per unit volume. In general,
Paper containing inorganic filler has filler between pulp fibers,
The strength is lowered by inhibiting the formation of inter-fiber hydrogen bonds and by making it difficult for hydrogen bonds to occur between the inorganic filler and the pulp fibers. In addition, the water-soluble polymer such as polyacrylamide resin or starch is directly intercalated between the pulp fiber, the water-soluble polymer and the pulp fiber by interposing between the pulp fibers that cannot reach a distance where hydrogen bonds can be generated. It is said that paper strength is enhanced by forming hydrogen bonds and indirect hydrogen bonds and increasing the number of hydrogen bonds per unit volume.

The polyamide resin particle of the present invention is a linear polymer having an acid amide bond —NHCO—, and the amide group can form a hydrogen bond with the pulp fiber, and the pulp fiber and the polyamide resin particle have a hydrogen bond. If they are not close enough to form a polyacrylamide resin, it is presumed that the paper strength-enhancing effect is also high due to the fact that a polyacrylamide resin or starch intervenes between them to form a direct and indirect bond. .

In particular, to a stock solution composition obtained by dissolving a polyamide resin in a solvent of a metal salt-organic solvent, one or more of the above-mentioned organic solvent or another organic solvent which is uniformly mixed with the above-mentioned organic solvent or water is added. When a slurry of polyamide resin particles obtained by precipitating the polyamide resin in the form of particles into particles and washing it with water to remove metal salts and organic solvents is used, the polyamide resin particles are And evenly dispersed. The reason is that the specific gravity of the particles is equivalent to the value of the pulp fiber, the average particle size of the particles is about 5 to 20 μm, and the particles have a porous irregular shape, so that the specific surface area is large, The slurry of polyamide resin particles according to the production method of the present invention has an optimum shape and properties for papermaking applications.

Paper was made according to a conventional method using the above-mentioned paper materials, dried, and calendered. When the paper was observed with an electron microscope, the polyamide resin particles were 100 to 200 μm in the paper layer.
It spreads in the shape of an amorphous amoeba of the size.
As described above, the polyamide resin particles have an average particle diameter of 5 to 20 μm in the slurry and are uniformly held between the pulp fibers and the pulp fibers when the paper layer is formed. During the treatment process, the polyamide resin particles are crushed and expanded in all directions, taking the form of an amoeba with an increased surface area and spreading between the pulp fibers, forming a strong hydrogen bond with the pulp fibers during the dehydration process. It is considered that the strength of paper is increased by bundling a large number of pulp fibers in addition to the above. In addition, the presence of the polyamide resin particles across the pulp fibers also fills the gaps in the paper, which improves the smoothness and air permeability of the paper, improves the surface strength, and improves the ink. The inking property is improved.

Further, the base paper for support produced by a conventional method using the above-mentioned paper materials has a good texture. Texture is the most basic quality of paper, and it is a necessary condition for printing paper to have good texture, which ensures printing workability and uniformity of print surface quality. In the case of poorly textured paper, pulp fibers form flocs and are unevenly distributed, so there are macroscopic irregularities on the surface of the paper. The meat becomes uneven,
Image reproducibility deteriorates. Good texture means that the surface of the paper has few macroscopic irregularities, and when the paper is exposed to light, it does not show cloud-like irregularities and looks like frosted glass. In the present invention, it is considered that by uniformly dispersing the porous polyamide resin particles and the pulp fiber, the formation of flocs in the pulp fiber is reduced and the texture is improved.

The strength of the paper is greatly affected by the beating degree (freeness) of the pulp used. When the beating degree of the pulp is increased, that is, the strength of the paper is considerably increased when the pulp fiber is fibrillated by beating the pulp fiber, as described above, considering the function in the paper layer by the addition of the polyamide resin particles of the present invention, By increasing the beating degree of the pulp, the polyamide resin particles can be spread over a larger number of pulp fibers, and the strength of the paper is further increased, and especially the folding endurance is significantly increased. . Also, the smoothness is considerably improved.

Since the polyamide resin particles obtained by heating and dissolving the polyamide resin in the solvent of the metal salt-organic solvent and precipitating by the above-mentioned production method are porous and white or cloudy opaque, they are mixed with pulp to make paper. The paper does not lose whiteness and opacity, but rather improves depending on the type of pulp. This point is a great difference in consideration that starch, polyvinyl alcohol, polyacrylamide and the like, which are usually used as a paper strengthening agent, become a transparent body after drying and reduce the opacity of paper.

When a yield improving agent is used in making a support base paper containing polyamide resin particles, the fixing rate of the polyamide resin particles in the paper is improved. When the polyamide resin particles have an average particle size of 5 to 20 μm and a particle size distribution of 70% or more of 3 to 30 μm and are dispersed in the slurry, they are suitable for uniform dispersion with pulp fibers.

[0054]

The present invention will be described below in detail with reference to examples. The present invention is not limited to the embodiments.
In the following examples, all parts and percentages are by weight unless otherwise stated. Moreover, various measurement and calculation methods were performed according to the following procedures. ◎ ・ Particle size distribution and average particle size: 0.1 using a light scattering type particle size distribution meter Mastersizer (manufactured by MALVERN)
Measure% concentration slurry. -Amount of particles in paper; The nitrogen content of particles, particle-containing paper, and non-particle-containing paper is determined by the Kjeldahl method, and the nitrogen content is converted to the particle content to calculate the content with respect to 100 parts of dry pulp. . -Basis weight; measured according to JIS (P-8124). -Thickness: Measured according to JIS (P-8118). -Whiteness: Measured with a Hunter whiteness meter using a blue filter according to JIS (P-8123). -Opacity: Measured according to JIS (P-8138). -Tear length: Calculated after measuring the tensile strength according to JIS (P-8113).・ Hoodie print surf roughness; ISO87
Measured at a clamping pressure of 20 kg / cm ² using a rubber backing disc according to 91. -Parker print surf porosity: Measured in the same manner as Parker print surf roughness except that the measuring head was changed to an air permeability measuring head. ◎ ・ Soil variation coefficient: The total area by the transmitted light method was used, and the soil variation coefficient was used as the soil formation evaluation scale. -Brightness of white paper; measured according to JIS (P-8142).・ Surface strength; using a Prüfbau multipurpose printing tester,
The tack ink is printed and the picking degree is visually determined. (5-stage evaluation, excellent = 5, poor = 1) <Test conditions> Temperature 23 ° C, humidity 50% Ink Toyo Ink printing plate Rubber blanket plate Printing pressure 15 N / m Printing speed 2.5 m / sec Dampening water 15 μl (isopropanol 10% aqueous solution) ・ Ink inking property: Using a Prüfbau multi-purpose printing tester, 250 μl of ink for off-rings was sequentially printed on five paper samples by reducing the amount of ink, and the ink amount on the plate was 3 g / m.
Ink transfer rate% at ² is measured. <Test conditions> Temperature 23 ° C, Humidity 50% Ink Toyo Ink Printing plate Metal plate Printing pressure 25N / m Printing speed 1.5m / sec ・ Printing glossiness: After printing blue with a gravure printing tester, Ministry of Finance Printing Bureau, printing solid The glossiness of the part is measured with a gloss meter.
It was measured according to IS (P-8142).

Example 1 24 kg of calcium chloride / dihydrate was stirred and dissolved in 56 kg of methanol at room temperature to obtain a 30 wt% calcium chloride / methanol mixed solvent. 3
kg of unstretched nylon 66 fiber is mixed with the above solvent 80 k
It was added to g and dissolved at room temperature with stirring. 120 kg of methanol was gradually added to this, and nylon particles were slowly precipitated by stirring. After gently stirring for 1 hour, the mixture was filtered, washed with a large amount of water without being dried, and washed with water until calcium chloride was not detected in the supernatant. Filtration using a 100 mesh wire,
Average particle size 10.3 μm, particle size distribution of 70% or more 3.2
22.6 μm porous amorphous nylon 66 particles (2.
5 kg of slurry was obtained. Obtained nylon particles 10
Department, Canadian Standard Freeness (C.
S. F. ) LBKP 90 parts beaten to 330 ml, light calcium carbonate 15 parts, talc 10 parts, cationic starch 1.0 part, emulsion type rosin sizing agent 0.15
Parts, and a pulp slurry having a concentration of 2% to which 0.5 part of a sulfuric acid band was added was used to make a base paper for a support using a paper machine capable of making high-quality paper. Subsequently, oxidized starch (SK20 manufactured by Nippon Corn Starch Co., Ltd.) and polyvinyl alcohol (Denka Poval K17 manufactured by Denki Kagaku Kogyo Co., Ltd.) were mixed at a weight ratio of 8: 2 and the mixture was steamed to adjust the concentration to 6%. ,
On-machine using a two-size press roll so that the coating amount on both sides is 2 g / m ² , and the total nip pressure is 40
On-machine calendering was carried out under the condition of kg / cm to obtain a clear size coated paper having a basis weight of 66 g / m ² , a thickness of 80 μm, an ash content of 12.6% and nylon particles of 8.2%. The total nip pressure means the total nip pressure of the rolls applied to the paper. Table 1 shows the results of the physical property test and the offset printing test of the obtained coated paper.

[Comparative Example 1] The base paper for support made in Example 1 was coated with no size press liquid and was not subjected to calendering. The basis weight was 65 g / m ² , the thickness was 101 μm, and the ash content was 12. A paper containing 6% of nylon particles and 8.2% of nylon particles was obtained. The results of the physical property test and the offset printing test of the obtained paper are shown in Table 1.

[Comparative Example 2] The total nip pressure of 40 kg was obtained without applying the size press liquid to the support base paper produced in Example 1.
On-machine calendar processing under conditions of / cm, basis weight 6
A paper having 7 g / m ² , a thickness of 82 μm, an ash content of 12.6%, and nylon particles of 8.2% was obtained. The results of the physical property test and the offset printing test of the obtained paper are shown in Table 1.

[Comparative Example 3] C.I. S. F. 100 parts LBKP beaten to 330 ml, 15 parts light calcium carbonate,
Supports a pulp slurry containing 10 parts of talc, 1.0 part of cationic starch, 0.15 part of emulsion type rosin sizing agent, and 0.5 part of sulfuric acid band at a concentration of 2% using a paper machine capable of making fine paper. The body raw paper was made into paper. Then, the same size press liquid as in Example 1 was applied on both sides at 2 g / m 2.
Apply in the same way to ² and total nip pressure 40kg
On-machine calendar processing under conditions of / cm, basis weight 6
A clear size coated paper having 6 g / m ² , a thickness of 78 μm and an ash content of 13.0% was obtained. Table 1 shows the results of the physical property test and the offset printing test of the obtained coated paper.

[Comparative Example 4] C.I. S. F. 90 parts of LBKP beaten to 330 ml, C.I. S. F. 2% concentration pulp slurry containing 10 parts of NBKP beaten to 600 ml, 15 parts of light calcium carbonate, 10 parts of talc, 1.0 part of cationic starch, 0.15 part of emulsion type rosin sizing agent, and 0.5 part of sulfuric acid band. The support base paper was made into paper by using a paper machine capable of making high-quality paper. Subsequently, the same size press liquid as in Example 1 was applied in the same manner so that the applied amount on both sides was 2 g / m ² , and the total nip pressure was 40 kg / c.
On-machine calendar processing under m condition, basis weight 66g
A clear size coated paper having a thickness of 79 μm / m ² , a ash content of 13.2% was obtained. Table 1 shows the results of the physical property test and the offset printing test of the obtained coated paper.

As shown in the results of Table 1, the PPS roughness was obtained for the uncalendered paper (Comparative Example 1) without providing a clear-size coating layer on the support base paper internally containing porous amorphous nylon 66 particles. (Surface roughness) was poor, surface strength and ink receptivity were poor, and offset printability was poor. Next, in the paper which was calendered without providing the clear size coating layer (Comparative Example 2), the PPS roughness was improved and the ink receptivity was improved, but the surface strength was poor. On the other hand, the calendered paper (Example 1) provided with a clear-size coating layer on the support base paper in which the porous amorphous nylon 66 particles of the present invention are added is
The PPS roughness was further improved, the ink receptivity was improved, the surface strength was improved, and a printing paper excellent in offset printing suitability was obtained. Further, the PPS roughness, the surface strength and the ink receptivity were also improved as compared with the paper in which nylon 66 particles were not added internally (Comparative Example 3 and Comparative Example 4). In addition, the formation is good and the breaking length is strong,
White opacity improved. Therefore, it is necessary to provide a clear size coating layer and carry out calendering treatment in order to obtain a printing paper having excellent print surface quality and suitability for offset printing. Furthermore, by internally adding porous polyamide resin particles to the support base paper as in the present invention, the surface strength and the ink receptivity are further improved, and the formation of the paper is improved, and the strength physical properties and It was possible to manufacture a printing paper having excellent optical properties and high smoothness.

[0061]

[Table 1] [Example 2] Calcium chloride-2 in 56 kg of methanol
37 kg of water salt was dissolved by stirring at room temperature to obtain a 40 wt% calcium chloride / methanol mixed solvent. 4.6 kg of drawn nylon 66 fiber waste was mixed with 93 k of the above mixed solvent.
It was added to g and allowed to swell by allowing it to stand at room temperature for 1 day, and then dissolved by heating and stirring at 40 ° C. After the temperature was returned to room temperature, 200 kg of methanol was gradually added to this, and the nylon particles were slowly precipitated by stirring. After slowly stirring for 1 hour, the mixture was filtered, washed with a large amount of water without drying, and washed with water until calcium chloride was not detected in the supernatant. Filtration using a 100 mesh wire,
Average particle size 12.0 μm, particle size distribution of 70% or more 3.8-
A slurry of 27.4 μm porous white amorphous nylon 66 particles (3.6 kg) was obtained. 10 parts of the obtained nylon particles, LBKP90 beaten to 250 ml of Canadian Standard Freeness (C.S.F.)
Parts, talc 8 parts, amphoteric starch 0.6 parts, emulsion type rosin sizing agent 0.5 part, and sulfuric acid band 0.6 part by using a paper machine capable of making high-quality paper from a pulp slurry having a concentration of 2%. The support base paper was made into paper. Subsequently, steamed oxidized starch (SK2 manufactured by Nippon Corn Starch Co., Ltd.)
0) Adjust the concentration to 8%, apply on-machine using a gate roll coater so that the coating amount on both sides is 0.8 g / m ^2, and perform on-machine calendering under the condition of total nip pressure of 87 kg / cm. And basis weight 62g / m ² , thickness 81μ
m, ash content 5.1%, and nylon particles 7.5% to obtain a clear size coated paper. Table 2 shows the results of the physical property test and the offset printing test of the coated paper obtained.

[Comparative Example 5] The total nip pressure of 87 kg was applied to the base paper for support made in Example 2 without applying the size press liquid.
On-machine calendar processing under conditions of / cm, basis weight 5
A paper having 9 g / m ² , a thickness of 75 μm, an ash content of 5.1% and nylon particles of 7.5% was obtained. The results of the physical property test and the offset printing test of the obtained paper are shown in Table 1.

[Comparative Example 6] C.I. S. F. 90 parts of LBKP beaten to 250 ml, C.I. S. F. NBKP beaten to 600 ml 10 parts, talc 8 parts, amphoteric starch 0.6
Parts, 0.5 parts of emulsion type rosin sizing agent and 0.6 parts of sulfuric acid band were used to prepare a base paper for support using a paper machine capable of making high-quality paper.
Subsequently, the same size press liquid as in Example 2 was applied in the same manner so that the applied amount on both sides was 0.8 g / m ² , and on-machine calendering was performed under the condition of a total nip pressure of 87 kg / cm. Amount 62 g / m ² , thickness 80 μm, ash 5.5
% Clear size coated paper was obtained. Table 2 shows the results of the physical property test and the offset printing test of the coated paper obtained.

Example 3 A support base paper obtained by papermaking using the same paper material as in Example 2 was adjusted to 8% concentration of steamed oxidized starch (SK20 manufactured by Nippon Corn Starch Co., Ltd.) and turned on. Using a gate roll coater on a machine, apply both sides so that the applied amount is 0.8 g / m ^2, and perform on-machine calendering under the condition of total nip pressure of 87 kg / cm, basis weight 46 g / m ² , thickness 60 μm, ash content 4.8
%, Nylon particles 6.2% to obtain a clear size coated paper. Table 2 shows the results of the physical property test and the offset printing test of the coated paper obtained.

[Comparative Example 7] The same size press liquid as in Example 3 was applied to the base paper for support obtained in Comparative Example 6 in the same manner so that the coating amount on both sides was 0.8 g / m ² . On-machine calendering was performed under the conditions of total nip pressure of 87 kg / cm, basis weight 46 g / m ² , thickness 61 μm, and ash content 5.2%.
A clear size coated paper of was obtained. Table 2 shows the results of the physical property test and the offset printing test of the coated paper obtained.

From the results of Comparative Example 6 in Table 2, when the ash content in the paper was 5.5%, the results of Comparative Example 4 in Table 1 (the ash content in the paper was 1
The opacity was reduced by about 2% as compared with 3.2%), but the paper in which 7.5% of porous nylon particles were internally added (5.1% ash content in the paper, Example 2) was used as Comparative Example 4. The paper had better opacity than the paper, and the breaking length was considerably better, and the surface strength and ink receptivity were also better. Basis weight is 46 g / m
All of the physical properties of the paper of Example 3, which corresponds to the lightweight paper of No. ² , were improved as compared with Comparative Example 7 in which the porous nylon particles were not added internally.

[0067]

[Table 2] [Example 5] Table 3 shows the results of the physical property test and the gravure printing test of the paper obtained by subjecting the clear-size coated paper manufactured in Example 1 to supercalendering under the conditions of 40 ° C and a total nip pressure of 240 kg / cm. Show.

[Comparative Example 8] The clear size coated paper produced in Comparative Example 4 was supercalendered under the conditions of 40 ° C and a total nip pressure of 240 kg / cm, and the results of the physical property test and gravure printing test of the paper were obtained. It shows in Table 3.

Example 6 The results of the physical property test and the gravure printing test of the paper obtained by subjecting the clear-size coated paper produced in Example 2 to supercalendering at 65 ° C. and a total nip pressure of 200 kg / cm are shown. It shows in Table 3.

Comparative Example 9 The clear size coated paper produced in Comparative Example 4 was supercalendered under the conditions of 65 ° C. and a total nip pressure of 200 kg / cm. It shows in Table 3.

As shown in the results of Table 3, the clear-size coated paper containing the porous amorphous nylon particles of Example 1 and Example 2 internally added by the super calendering process, the nylon particles were internally added. The white paper glossiness was 20% or more compared to the paper without addition, and the print glossiness after the gravure printing test was significantly improved.

[0072]

[Table 3]

[0073]

EFFECT OF THE INVENTION A printing paper which is calendered by providing a clear-size coating layer on a support base paper internally containing porous amorphous polyamide resin particles produced by the present invention has good texture and strength physical properties. Without impairing the opacity, the surface strength and ink receptivity during offset printing were improved. Further, the supercalender treatment further improved the glossiness of white paper, and the print glossiness by gravure printing was significantly improved.

In the production of this printing paper, by using a slurry in which pulp and porous amorphous polyamide resin particles are uniformly dispersed in water, it is possible to obtain a support base paper having a constant quality and good texture. it can. Furthermore, when the polyamide resin is dissolved in a solvent of a metal salt-organic solvent and then the polyamide resin particles precipitated again in the form of porous amorphous particles are used in an aqueous slurry state, the polyamide resin is used against the pulp slurry. The particle slurry can be added as it is, and the stirring and dispersing step as a pretreatment step for adding particles can be omitted, which is suitable for actual operation. The polyamide resin particles are a white (white turbid) opaque body, and the opacity of the paper is increased to maintain the natural texture of the paper. Moreover, by calendering, the various strengths of the paper are further improved due to the presence of the amoeba spread over the pulp fibers. Further, the polyamide resin particles are a porous body, present between the pulp fibers constituting the support base paper and in the voids, the paper smoothness is improved because it spreads in an amoeba form by calender treatment,
Improves surface strength and ink receptivity during offset printing.

Claims (5)

[Claims] 1. After dissolving a polyamide resin in a solvent of metal salt-organic solvent in a raw material mainly composed of pulp and filler,
The white opaque polyamide resin particles are precipitated by adding one or more selected from the above organic solvent, another organic solvent which is uniformly mixed with the above organic solvent, and water, and further washed with water to wash the metal salt and the organic salt. 0.2-2 g / m ^{2 of} clear-size paint is applied on at least one side of a support base paper composed of a base material containing 2 to 20% by weight of porous polyamide resin particles produced by removing the solvent. Printing paper having a Parker print surf roughness (ISO8791) of 2 to 5 μm. 2. The printing paper according to claim 1, wherein the clear size paint is starch or a mixture of starch and a natural polymer or a synthetic polymer. 3. The printing paper according to claim 1, wherein Parker print surf porosity is 100 to 500 ml. 4. After dissolving a polyamide resin in a solvent of a metal salt-organic solvent in a raw material mainly composed of pulp and filler,
The white opaque polyamide resin particles are precipitated by adding one or more selected from the above organic solvent, another organic solvent which is uniformly mixed with the above organic solvent, and water, and further washed with water to wash the metal salt and the organic salt. After the porous polyamide resin particles produced by removing the solvent are contained in an amount of 2 to 20% by weight to adjust the raw material, the raw material is made into paper by a conventional method to prepare a base paper for a support. A method for producing printing paper, which comprises applying a clear-size paint on a base paper at least on one side in an amount of 0.2 to ² g / m ² and calendering it. 5. The method for producing gravure printing paper according to claim 4, wherein the calendering treatment is a super calendering treatment, and the blank surface glossiness of the coated surface is treated to 20 to 25%.