FR2670810A1 - COATING COMPOSITION FOR JOURNAL PAPER. - Google Patents

Abstract

Disclosed is a coating composition for newsprint, having excellent properties for offset printing when used in high-speed web offset printing of the cooling-drying type, such as peel resistance. , printing gloss and printability. This composition comprises, per 100 parts by weight of a pigment, of which preferably 50% by weight or more consists of a clay, from 3 to 50 parts by weight, and preferably from 5 to 40 parts by weight, in solids , of an amphoteric copolymer latex obtained by copolymerizing an ethylenically unsaturated amine with butadiene or the like. This composition may contain at most 15 parts by weight, preferably at most 10 parts by weight, of a water-soluble polymeric binder such as starch esterified with phosphoric acid, in addition to the amphoteric copolymer latex, but in such an amount. that the total amount of the pigment binders is 3 to 50 parts by weight, as solids, per 100 parts by weight of pigment.

Description

COATING COMPOSITION FOR JOURNAL PAPER

  This invention relates to a coating composition for paper for newspaper printing (hereinafter referred to as a "newspaper coating composition"), suitable for polychrome offset printing. coating composition for newsprint having excellent properties for offset printing, when used in fast-drying web offset printing of the cooling-drying type, such as peel strength, gloss impression

  and printability (receptivity for the ink).

  Recently, polychrome printing has made a remarkable appearance in daily newspapers, especially in sports journals, and there is also a rapid increase in the full-color printing of daily newspaper pages. However, these printed polychrome newspapers have a mediocre appearance, compared to that of inserted sheets whose material is often coated paper, and they are therefore only weakly attractive to readers. On the other hand, because of the social mission of newspapers, it is necessary to print them in large quantities in a short time. As a result, printing speeds increase more and more, and one wishes to improve important properties. for offset printing, such as tearing and drying (or fixing) the ink. Heretofore, as a countermeasure for polychrome printing and offset printing, a method has been adopted in which tear resistance is increased by using starch, polyvinyl alcohol or However, by this method, satisfactory properties have not been obtained for offset printing, for example with regard to the printing gloss. Recently, in order to improve these characteristics, it has been proposed to use a pigmented coating, the amount of oil absorbed in the deposited layer being increased by the choice of the pigment

  (Published Japanese Patent Nos. 174697/1989 and 169768/1990).

  Improved processes are also known in which a large amount of a pigment binder or an organic pigment is used (Japanese Patent Publication Nos. 19595/1990 and 74698/1990). However, these methods can not meet all the requirements. relating to properties important for printing on a web offset and cooling-drying press, using a cooling-drying type ink, properties such as ink drying, pull-out resistance, gloss In addition, these processes can not produce newsprint having gloss, opacity, etc., in addition to the properties of the paper.

  important for offset printing, mentioned below.

  above. The Applicant has researched to overcome the disadvantages of the prior art, and has contemplated, as a method of achieving this goal, the use of a customary coating composition for low weight paper. However, according to this method, in the case of polychromic offset printing using a cooling drying ink, the coated paper absorbs poorly the oil and the water, and therefore exhibits poor ink drying and printability properties, and therefore can not obtain newsprint having excellent properties for offset printing and therefore suitable for

polychrome printing.

  As a result, the Applicant has continued its research As a result, it has found that by using an amphoteric copolymer latex as a pigment binder and adjusting the amount of this pigment binder within a suitable range, but without changing the composition. of pigment which has been used generally until now for coated paper and low weight paper, it is possible to obtain newsprint whose important properties for offset printing, such as the drying of the ink, water loss, tear resistance (particularly wet wet tear resistance) and print gloss are remarkably improved, and also good brilliance, good opacity, etc. It is on the basis of this discovery that has been established this

invention.

  Therefore, according to the present invention, there is provided a coating composition for paper for newspaper printing, which composition comprises parts by weight of a pigment, and as a binder for pigment, from 3 to 50 parts by weight, in solids, a latex

of amphoteric copolymer.

  According to the present invention, there is further provided a newspaper coating composition, which comprises, as a pigment binder, at most 15 parts by weight of a water-soluble polymer compound, in addition to the amphoteric copolymer latex, in a proportion such that the total amount of pigment binder is from 3 to 50 parts by weight, solids, per 100 parts by weight of pigment. The amphoteric copolymer latex which is used as the pigment binder in the present invention may be a copolymer latex which gels for a certain pH value, and which can be obtained by introducing a specific monomeric unit into a copolymer or by polymerizing monomers with an amphoteric surfactant, or by another method

known.

  The monomers used for the synthesis of the amphoteric copolymer latex which will be used in this invention are not particularly limited, nor their respective proportions, but a monomer mixture having from 20 to 50% by weight of a monomer is usually used. conjugated aliphatic diene monomer, from 74% by weight of a vinyl aromatic monomer, from 0.5 to% by weight of an ethylenically unsaturated acidic monomer, and from 0 to 40% by weight of a monomer

  copolymerizable with the monomers indicated above.

  The conjugated aliphatic diene gives the polymer a certain flexibility When the proportion of this monomer is less than 20% by weight, the copolymer becomes too hard, and when it is greater than 50% by weight, the water resistance decreases.

  of conjugated aliphatic dienes are 1,3-

  butadiene, 2-methyl-1,3-butadiene, 2-chloro-1,3-

  butadiene, etc., with particular preference for 1,3-butadiene. The use of the vinyl aromatic monomer makes it possible to impart to the copolymer an appropriate hardness and water resistance. However, a proportion of less than 10% by weight of this monomer does not give satisfactory effects, and when it is used more of 74% by weight, a decrease in the film-forming and adhesion properties of the copolymer is observed. Examples of vinyl-aromatic monomers,

  there may be mentioned styrene, α-methyl-styrene, mono-

  chlorostyrene, vinyl toluene, etc., and among these,

prefer styrene.

  It is advisable to use an ethylenically unsaturated acidic monomer in order to increase the adhesion strength of the copolymer and to improve the stability of the copolymer latex in the colloidal state. But when the proportion of this monomer is less than 0.5. % by weight, the effects mentioned above can not be obtained, and when more than 20% by weight is used, there is a problem of stability of the polymerization system, or other problems. As the monomer used an ethylenically unsaturated amine, the ethylenically unsaturated acidic monomer also plays a role in the adjustment of the gel point. In this case, when an excessively large proportion of ethylenically unsaturated acidic monomer is used, the resulting copolymer latex is obtained. has a gelling point which does not correspond to the purpose of the present invention. Particular examples of ethylenically unsaturated acidic monomers are unsaturated carboxylic acids, such as acrylic acid, methacrylic acid, crotonic acid, cinnamic acid, itaconic acid, fumaric acid, maleic acid and butene-tricarboxylic acid, alkyl esters of unsaturated polycarboxylic acid, these esters comprising at least one carboxyl group, such as monoethyl itaconate, monobutyl fumarate and monobutyl maleate, unsaturated sulphonic acids or their salts, such as the sodium salt of the acrylate, sulfoethyl, the sodium salt of sulfopropyl methacrylate, and acrylamido-propane sulfonic acid, etc. In the course of synthesizing an amphoteric copolymer latex for use in this invention, a copolymerizable monomer can be copolymerized with the above-mentioned monomers. If needed, it is preferable to use this monomer to 40% by weight or less. Particular examples of such monomers are unsaturated carboxylic acid alkyl esters, such as methyl acrylate, methyl methacrylate, ethyl acrylate and butyl acrylate. ethylenically unsaturated nitriles, such as acrylonitrile and methacrylonitrile, hydroxyalkyl esters of unsaturated carboxylic acid, such as B-hydroxyethyl acrylate,

  B-hydroxypropyl acrylate and B-methacrylate

  hydroxyethyl, unsaturated carboxylic acid amides and

  their derivatives, such as acrylamide, methacrylamide, N-

  methylol-acrylamide and diacetone-acrylamide, glycidyl esters of unsaturated carboxylic acid, such as glycidyl acrylate and glycidyl methacrylate, and other vinyl compounds such as acrolein and allyl alcohol, etc. unsaturated carboxylic acid gives the copolymer a moderate hardness, and at the same time increases the air permeability of the copolymer, and is preferably used in an amount of 5 to 30% by weight. 40% by weight, it has an adverse influence on the water resistance and other properties An ethylenically unsaturated nitrile exerts an action of increasing the printing gloss of the coated paper, and preferably uses a amount of 5 to 30% by weight If more than 40% by weight is used, the printability of the coated paper is lowered and the drying of the ink on the coated paper takes less effect A hydroxyalkyl ester The unsaturated carboxylic acid improves the mechanical stability of the copolymer latex. By using an unsaturated carboxylic acid amide or a derivative of such a compound, it is possible to improve the chemical stability, mechanical stability and water resistance of the latex of

copolymer.

  When using a comonomer to introduce a gelation site into the copolymer, as a method for obtaining an amphoteric copolymer latex, this comonomer is used in a proportion of 0.5 to 20% by weight, preferably 1 at 10% by weight, based on all the monomers If less than 0.5% by weight is used, it is difficult to make the amphoteric latex, whereas if more than 20% is used by weight, it becomes difficult to confer a suitable gel point for the composition of the invention, and furthermore, there are problems, for example, that of the formation of a large amount of coagulate at the time of preparation a latex

of copolymer.

  As examples of monomers used to introduce a gelation site into the copolymer, mention may be made of ethylenically unsaturated amines, represented by the general formula

R 1 __R 3

CH 2 = C-A-R 2-N (R

  R 4 in which R 1 represents a hydrogen atom or a methyl group, R 2 represents an alkylene group containing from 2 to 10 carbon atoms, R 3 and R 4 each independently represent a hydrogen atom or a group alkyl having 1 to 12 carbon atoms, and A represents

-CO-, -CONH or -O-.

  Particular examples of the ethylenically unsaturated amine are the aminoalkyl esters of ethylenically unsaturated carboxylic acids, such as methylaminoethyl (meth) acrylate, (meth) acrylate and the like.

  t-butylaminoethyl, N, N-dimethylamino (meth) acrylate

  ethyl, N, N-dimethylaminopropyl (meth) acrylate, diethylaminoethyl (meth) acrylate and dibutylaminoethyl (meth) acrylate, aminoalkylamides of ethylenically unsaturated carboxylic acid, such as

  methylaminoethyl (meth) acrylamide, N, N-dimethylamino-

  ethyl (meth) acrylamide and N, N-dimethylaminopropyl-

  (meth) acrylamide, aminoalkyl-vinyl-ethers, such as aminoethyl-vinyl-ether, methylaminoethyl-vinyl-ether

  and N, N-dimethylaminoethyl vinyl ether, vinyls

  pyridines such as 2-vinylpyridine, 4-

  vinylpyridine, 2-methyl-5-vinylpyridine and 2,4-

  diethyl-5-vinylpyridine, etc. It is also possible to obtain an amphoteric copolymer latex for use in this invention using a surfactant of a suitable kind. This kind of surfactants includes cationic surfactants and amphoteric surfactants. One may use such a surfactant together with a nonionic surfactant. or similar, during the emulsion polymerization of the monomer mixture indicated above, or add this surfactant after the polymerization carried out using a nonionic surfactant or the like The amount of such a cationic or amphoteric surfactant used is 0.1 to 5% by weight, preferably 0.2 to 2% by weight,

relative to the weight of the copolymer.

  Cationic surfactants useful for the purpose indicated above are suitable for surfactants of the quaternary ammonium salt type. Specific examples of these surfactants are lauryltrimethylammonium chloride, cetyltrimethylammonium chloride, lauryl bromide and the like. trimethyl ammonium chloride (derived radicals

  beef tallow) -trimethylammonium chloride, N

  (dodecyl-colamino-formyl-methyl) -pyridinium, cetylethyl-morpholinium ethylsulfate, etc. Particular examples of amphoteric surfactants include amphoteric surfactants of the alkylimidazoline type, etc. The gel point of the amphoteric copolymer latex can be adjusted by varying the nature and amount of certain monomers used in copolymer synthesis, such as an ethylenically unsaturated acidic monomer, an ethylenically unsaturated amine monomer, and a hydrophilic monomer. The gel point can also be adjusted by varying the nature or amount of an emulsifier, or the nature or amount of an initiator. It is preferred to adjust the gel point of the copolymer latex used in this invention. in the pH range from 3.5 to 8.5 The gel point can be measured according to the process described in published Japanese Patent No.

49360/1984.

  An amphoteric copolymer latex for use in this invention can be prepared by a known emulsion polymerization process. There is no particular restriction on the temperature or pressure of polymerization, nor on how to add the monomers, etc., or to the adjuvants used for the polymerization (polymerization initiator, molecular weight modifier, adjusting agent

p H, etc.).

  The pigments used in this invention are not particularly limited, and may be mentioned, as particular examples, inorganic pigments such as clays, calcium carbonate, aluminum hydroxide, titanium white, barium sulfate, satin white and talc, as well as organic pigments such as polystyrenes and phenolic resins. These pigments can be used alone or in combination. In order to fully exert the effects of the invention, it is preferable that the pigments are 50% or

  more, a clay, and in particular kaolinite.

  The newsprint coating composition of the present invention comprises a pigment and amphoteric copolymer latex as the indispensable binder for the pigment. The amount of amphoteric copolymer latex is from 3 to 50 parts by weight, solids, per 100 parts. by weight of pigment, preferably 5 to 40 parts by weight and more preferably 10 to 40 parts by weight When this amount is less than 3 parts by weight, it becomes difficult to prevent the migration of the binder during the process of drying, at the time of preparation of the coated newsprint, and therefore, the printability becomes unsatisfactory and the important properties for offset printing, such as tear resistance and print gloss, become poor Other on the other hand, when more than 40 parts by weight are used, the adhesion resistance between sheets decreases due to the tackiness and other properties of the latex, and In particular, when this quantity exceeds 50 parts by weight, this tendency reaches a point at which the paper is made practically unusable, and at the same time, the gloss, the opacity, the loss of water, ink drying and other properties of paper

  got laid newspaper become bad.

  In the present invention, it is possible to use together, as a binder for pigment, a binder constituted by a water-soluble polymer. Although it is not essential to use this water-soluble binder, when it is used together, It becomes easier to adjust the viscosity of the dipping bath, and effects on the opacity and adhesive strength of newsprint are observed. Particular examples of water-soluble polymeric binders are starches, such as a starch esterified with phosphoric acid and an enzyme-modified starch, casein, polyvinyl alcohol, cellulose derivatives such as methylcellulose and carboxymethylcellulose, etc., but other water-soluble polymeric binders can also be used which are

  usually used in this technical field.

  The amount of water-soluble polymer binder is 15 parts by weight or less, and preferably 10 parts by weight or less, solids, per 100 parts by weight of pigment When the amount of water-soluble polymer binder is greater than 15 parts by weight, observes an increase in the viscosity of the bath and a decrease of its fluidity, and therefore, it becomes more difficult to make the coating It is necessary that the amount of this water-soluble polymer binder is in an interval such that the total of the amount of this binder and the amount of the other essential binder for pigment, namely the amphoteric copolymer latex, is from 3 to 50

  parts by weight, per 100 parts by weight of pigment.

  In addition, it is also possible, provided that this does not interfere with the effect of the invention, to use, as a binder for pigment, in the coating composition of the invention, plastic latexes of styrene copolymers and butadiene, copolymers of

  methyl methacrylate and butadiene, or the like.

  It is furthermore possible to add, if necessary, to the coating composition of this invention, in addition to water, pigment and pigment binder, pigment dispersing agent, viscosity modifier, water retention agent, an insolubilizing agent, a dye, a fluorescent dye, a lubricant, a pH adjusting agent, an antifoaming agent, a surfactant, an antiseptic, or other similar agents. In the present invention, it is necessary to maintain the p H of the coating composition at a value equal to or greater than the gel point of the amphoteric copolymer latex. When the pH is below this gel point, the printability improving effect decreases. Although there are no particular restrictions on the pH adjusting agent, preferably of

ammonia.

  It is not clear why the coating composition of this invention has excellent properties for offset printing, but it is believed that one of the possible reasons is as follows. printability and other properties are poor is caused by a non-homogeneous distribution of the binder during the drying process carried out during the coating of the paper with a bath of layer, and that this inhomogeneity is caused by what is called the On the other hand, the pH of the dipping bath is lowered during the drying process, and if an amphoteric copolymer latex is used as pigment binder, the latter gels when the pH reaches the As a result, the distribution of the binder becomes homogeneous and excellent printability is obtained. This invention is further illustrated in the following examples: Unless otherwise indicated, parts

  and percentages given in these examples are by weight.

  In addition, the weight proportions of latex are referred to the solids. In the examples, the various characteristics of the diapers and coated papers are evaluated

according to the following methods.

  Viscosity of the bath of layer A viscometer of the type BL is used The viscosity of the bath of layer is given by the value (in m Pa s) measured after one minute at 60 rpm, using the rotor

n I 4.

  Layer bath fluidity A high shear viscosimeter of the Hercules type is used. The fluidity of the plating bath is given by the apparent viscosity (in m Pa s) for a number of turns.

  of 4000 rpm, with a G element (0,02 cm of air gap).

  Drying of the Ink Using an RI tester (produced by Akira Seisaku-sho Co., Ltd.), a solid printing is done with a newspaper ink, and a coated sheet of paper is placed on top of it. then, by visual observation, the degree of transfer of the ink on

  evaluates the drying of the ink on a five-degree scale.

  The grade 5 is the best and the grade 1 the worst.

  Water Loss After applying the fountain solution with a rubber roller, flat-coated newspaper is subjected to flat printing, using an RI tester and a newspaper ink, and the degree of ink transfer (concentration of ink) is estimated by visual observation The water loss is evaluated on a five-degree scale. Note 5 is the

better and the rating 1 is the worst.

  Resistance to dry tearing It is estimated, by visual observation, the degree of tearing when performing an impression using an RI tester and a tear test ink, whose adhesiveness index is 24 Dry peel strength is evaluated on a five-degree scale.

  5 is the best and 1 is the worst.

  Moisture resistance After applying water with a Molton roller, coated newspaper is subjected to solid printing, using an RI tester and a tear test ink. , whose adhesiveness index is 16, and the degree of tearing is estimated by visual observation The resistance to pulling on wet is evaluated on a five-degree scale, the score being the best

and the note 1 the worst.

  Printing Gloss After printing in a solid state using an RI tester and a newspaper ink, the print gloss is measured using a

  Glarimeter (produced by Murakami Shikisai Co, Ltd, GM-

26 D).

  Whiteness Whiteness is measured using a Hunter reflectometer (produced by Murakami Shikisai Co., Ltd., CM-8 P), and is expressed as a percentage whiteness is all

  better than the value is higher.

  Opacity Opacity is measured using a Hunter reflectometer (produced by Murakami Shikisai Co., Ltd., CM-8 P), and is expressed as a percentage.

  better than the value is higher.

  Resistance to Surface Adhesion Surface adhesion resistance is expressed as the adhesion of a coated newspaper to a metal roll when the paper is passed twice in a supercalender at 170 ° C. C and under a load

of 150 kg / cm.

  O: no adhesion / A: low adhesion X: considerable adhesion Preparation of amphoteric copolymer latex In an autoclave equipped with an agitator, 32 parts of water, 1.1 parts of tetrasodium ethylenediaminetetraacetate, 1.1 part of sodium lauryl sulphate and 0.2 part of potassium persulfate, then one tenth of a monomer emulsion prepared separately in a vessel equipped with a stirrer, this emulsion having the composition indicated in Table 1 is heated the reaction system at 80 ° C to react for 1 hour Then is added 0.8 part of potassium persulfate, together with 20 parts of water, and is then introduced into the autoclave, in 4 hours and continuously the remaining nine tenths of the monomer emulsion Meanwhile, the autoclave is maintained at 80 ° C. The reaction system is then maintained at 80 ° C. for an additional hour, and then ammonia is added. to adjust the pH of the latex to 9.0 Then 4.0 parts of water, 2.0 parts of N, N-dimethylaminoethyl methacrylate and 0.1 part of ammonium persulfate are added, and the reaction mixture is reacted. at 80 ° C. for 2 hours. Thus, the amphoteric copolymer latexes A, B and C are obtained. The gelation points

  these latexes are all at pH 7.0.

Table 1

  Latex ABC Water 50.0 parts 50.0 parts 50.0 parts Sodium lauryl sulphate 0.3 0.3 0.3 Sodium bicarbonate 0.5 0.5 0.5 Styrene 20.5 50.5 21, 0 Butadiene 45.0 35.0 40.0 Acrylonitrile 10.0 O 20.0 Methyl methacrylate 20.0 10.0 15.0 Methacrylic acid o 0.2 2.5 O Acrylic acid o O 2.0 t- dodecylmercaptan 0.2 0.13 0.25 Preparation of usual latices of styrene and butadiene copolymer, not having a gelling point In an autoclave equipped with an agitator, 32 parts of water, 1.1 parts of water, are introduced. of tetrasodium ethylenediamine tetraacetate, 1.1 parts of sodium lauryl sulphate and 0.2 part of potassium persulfate, and one tenth of a monomer emulsion prepared separately in a tank equipped with a stirrer, this emulsion having a composition indicated in Table 2 The reaction system is heated at 800 ° C. to react for 1 hour. 0.8 part of potassium persulfate is then added thereto. together with 20 parts of water and then introduced into the autoclave, continuously and in 4 hours, the remaining nine tenths of the monomer emulsion Meanwhile, the autoclave is maintained at 800 C is continued The reaction is carried out at 800 ° C. for 2 additional hours. Thus, the latexes D, E and F are obtained. None of these latices has a gelling point.

Table 2

  Latex DEF Water 50.0 parts 50.0 parts50.0 parts Sodium lauryl sulphate 0.3 0.3 0.3 Sodium bicarbonate 0.5 0.5 0.5 Styrene 20.5 43.0 26.5 Butadiene 45.0 40.0 42.0 Acrylonitrile 10.0 O 15.0 Methyl methacrylate 20.0 15.0 15.0 Methacrylic acid 0.2 O 1.5 Acrylic acid O 2.0 O t-dodecylmercaptan 0 0.17 0.3 Newspaper Coating Compositions According to the coating bath formulation shown in Table 3 below and using the latexes A to F, the bath layer compositions N 1 to 6 are prepared. for newsprint, compositions each having a

  concentration of 50% solids and a pH of 9.5.

Table 3

  Clay Crushed Calcium Carbonate Dispersant (1) Sodium Hydroxide Phosphoric Acid Starch (2) Latex Parts Parts 0.2 Part 0.2 Part 6 Parts Parts (1) Sodium Polyacrylate, Product of Toagosei Chemical Co, Ltd , Aron T-40 (2) Product of Nihon Shokuhinkako Co, Ltd,

MS-4600

Example 1

  Sheets of newsprint paper are coated with each of the thus obtained soaking baths under the conditions shown in Table 4 below. The coated newsprint is kept in an air conditioned room at a temperature of 200. C and at a relative humidity of 65 5% for one day and one night, then subjected to various evaluation tests The results of these tests are indicated

in Table 5.

Table 4

  Device Drying Grille Backing paper Coating weight: Laboratory coater: hot air oven, 1300 C, seconds: laboratory supercalender, C, 55 kg / cm, 2 contact areas: newsprint (46 g / m 2 ): 5 g / m 2 / side

Table 5

  Example of this Comparative Example Invention Layer Bath 1 2 3 4 5 6 Latex ABCDEF Drying Ink 4.3 4.5 4.0 3.5 4.0 3.0 Loss of Water 4.5 5.0 4.0 2.0 3.5 1.0 Properties Resistance to dry tearing 4.7 4, 5 4.3 4.2 4.3 4.0 Moisture resistance 4.0 5, 0 4.5 3.5 3.0 3.2 evaluated Gloss print 44.6 42.2 48.8 39.3 38.9 40.4 Whiteness 63.4 63.3 62.9 60.1 59 , 9 59.6 Opacity 91.1 91.2 91.2 86.3 87.1 86.9 K \) w K) M "Il G al FG> Based on the results presented in Table 5, we see that in the case of use of the NO 1 to 3 layer baths of this invention which contain an amphoteric latex, coated press paper having excellent ink drying properties can be obtained. of water, tear resistance, printing gloss, whiteness and opacity, whereas in the case where the NI 4 to 6 layered baths, which contain usual latices, are used, can only obtain

  coated papers, all of which are mediocre.

Example 2

  Coated newsprint was prepared in the same manner as in Example 1, except that NO 7 to 12 layer baths were obtained from the coating bath formulations shown in Table 6 and which latex A or D is used, and this coated newsprint is subjected to the same various evaluation tests as in Example 1 The results obtained are presented

in Table 7.

Table 6

  Example of This Comparative Example Invention Latex A Latex D N layer bath 7 8 9 10 111 12 Clay 60.0 60.0 60.0 60.0 60.0 60.0 Crushed calcium carbonate 40.0 40.0 40 , 0 40.0 40.0 40.0 Dispersant (1) 0.2 0.2 0.2 0.2 0.2 0.2 Sodium hydroxide 0.2 0.2 0.2 0.2 0, 0.2 Ether starch with phosphoric acid (2) 7.0 7.0 7.0 7.0 7.0 7.0 Latex 15.0 25.0 35.0 15.0 25.0 35, 0 (1) Sodium polyacrylate, product of (2) Product of Nihon Shokuhinkako Co., Toagosei Chemical Co., Ltd., Aron T-40 Ltd, MS-4600 A K) M "II GFG

Table 7

  Example of this Comparative Example Invention N layer bath 7 8 9 10 i 111 12 Ink drying 5.0 5.0 4.0 4.0 2.0 1.0 Loss of water 4.8 4.5 4.0 3.0 2.3 1.0 Properties Tear resistance 4.5 5, 0 5.0 4.0 4.5 5.0 Moisture resistance 4.0 5, 0 5.0 3.0 4.5 5.0 evaluated Print Gloss 40.2 48.6 55.3 34.3 41.9 52.3 Whiteness 63.3 64.2 64.5 62.1 61 , 62.2 Opacity 91, 91.1 90.8 90.2 90.0 89.8 o '. From the results shown in Table 7, it can be seen that in the case where the No. 7 to 9 diapers of this invention are used, as the amount of pigment binder increases, the tear resistance and print gloss are increased, and at the same time, coated newsprint exhibits excellent ink drying, water loss, whiteness and opacity properties, while in the case where the NO 10 to 12 layer baths, which contain usual latices, are used, although the gloss and peel strength increase with the amount of pigment binder, ink drying and loss of water are significantly reduced, and only coated newsprint can be obtained that does not support practical use as

than newsprint.

Example 3

  Coated newsprint was prepared in the same manner as in Example 1 except that the NO 13 to 20 layer baths obtained from the coating bath formulations shown in Table 8 and with latex A, and this newsprint is subjected to the same various evaluation tests as in Example 1.

  The results are shown in Table 9.

Table 8

  N layer bath 13 14 15 16 17 18 19 20 Clay 80.0 80.0 80.0 80, 0 80.0 80.0 80.0 8 Calcium carbonate granules 20.0 20.0 20.0 20 , 0 20.0 20.0 20.0 20.0 Dispersant (1) 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 Sodium hydroxide 0.2 2 0.2 0.2 0.2 0.2 0.2 0.2 Starch with phosphoric acid (2) 13.0 5.0 O 3.0 O 18.0 O Poly (vinyl alcohol) ( 3) O 8.0 8.0 O 20.0 Latex 7.0 15.0 30.0 20.0 40.0 45.0 2.0 15.0 (1) Sodium polyacrylate, product of Toagosei Chemical Co , Ltd., Aron T-40 (2) Product of Nihon Shokuhinkako Co., Ltd., MS-4600 (3) Product of The Nippon Synthetic Chemical Industry Co., Ltd., NM-11 Co K) M "It GFG

Table 9

  EXAMPLE OF THIS INVENTION COMPARATIVE EXAMPLE Bath Layer NO 13 14 15 16 17 18 19 20 Bath Viscosity 880 760 810 780 690 700 1670 1980 Bath Fluidity 53 43 44 44 43 55 79 99 rn Resistance to Adhesion QOOOOXQQOO <Drying ink 4.6 5.0 5.0 5.0 3.8 1.0 4.7 3.8 Loss of water 4.8 5.0 4.5 5.0 4.2 1.0 3 , 8 3.5 tn Resistance to dry tearing 4.0 4.5 5.0 5.0 5.0 4.5 1.0 4.0 Resistance to wet tearing 4.0 4.5 5.0 5.0 5.0 4.7 1.0 3.5 Gloss paper 40.3 44.1 56.2 47.2 60.1 62.0 32.8 40.6 Whiteness 63.9 64 , 1 62.4 64.2 62.6 60.3 58.3 59.4 Opacity 92.3 92.0 90.8 91.7 91.4 88.4 92.3 93.2 \ D "It o From the results shown in Table 9, it can be seen that in the case where the inventive layer baths are used, coated press paper having excellent ink drying properties is obtained. loss of water, tear resistance, gloss, whiteness and opacity. But in the case where the amount of binder for If the pigment is too large (bath NO 18), a coated newspaper is obtained which has markedly poor properties of drying the ink and losing water; in the case where the amount of amphoteric copolymer latex is too low (NI 19 bath), there is obtained a coated newspaper having a very low resistance to tearing; in the case where the amount of water-soluble polymer binder is too great (baths NO 19 and 20), the viscosity of the bathing bath becomes too high and coated papers having various properties are obtained.

are mediocre.

  Thus, according to the invention, it is possible to obtain a coated newspaper that has, compared to that obtained according to the prior art, much better drying properties of ink, water loss, resistance to tearing, especially wet, and glossy, important properties for offset printing with ink drying by cooling,

  as well as comparable whiteness and opacity.

Claims (5)

  A coating composition for newsprint, characterized in that it comprises, for 100 parts by weight of a pigment, from 3 to 50 parts by weight, in solids, of an amphoteric copolymer latex as a binder for pigment . The coating composition for newsprint according to claim 1, characterized in that it comprises, as a pigment binder, in addition to the amphoteric copolymer latex, a water-soluble polymer in an amount not exceeding 15 parts by weight. weight and which is such that the total amount of the pigment binders is from 3 to 50 parts by weight, in solids, per 100 parts by weight. pigment weight.   3 A coating composition for newsprint according to claim 1, characterized in that it contains, per 100 parts by weight of pigment, from 5 to 40 parts by weight, in solids, of copolymer latex   amphoteric as a binder for pigment.   The coating composition for newsprint according to claim 2, characterized in that it comprises, as a binder for pigment, in addition to the amphoteric copolymer latex, a water-soluble polymer in an amount not exceeding 10 parts by weight. weight and which is such that the total amount of the pigment binders is from 3 to 50 parts by weight, in solids, per 100 parts by weight. pigment weight.   Printing composition for newsprint, according to claim 3, characterized in that it comprises, as a binder for pigment, in addition to the amphoteric copolymer latex, a water-soluble polymer in an amount which does not exceed 10 parts by weight and which is such that the total amount of the pigment binders is from 5 to 40 parts by weight, in solids, per 100 parts by weight. pigment weight.   6 Coating composition for newsprint,   according to any one of claims 1 to 5,   characterized in that the amphoteric copolymer latex is a latex obtained by copolymerizing a monomer mixture comprising from 20 to 50% by weight of a conjugated aliphatic diene monomer, from 10 to 74% by weight of a vinyl monomer, aromatic, from 0.5 to 20% by weight of an ethylenically unsaturated acidic monomer, from 0.5 to 20% by weight of a monomer for introducing into the copolymer a gelling site of the copolymer, and   plus 40% by weight of a monomer copolymerizable therewith.   7 Coating composition for newsprint,   according to any one of claims 1 to 5,   characterized in that the amphoteric copolymer latex is a latex obtained by copolymerizing a monomer mixture comprising from 20 to 50% by weight of a conjugated aliphatic diene monomer, from 10 to 74% by weight of a vinyl monomer, aromatic, from 0.5 to 20% by weight of an ethylenically unsaturated acidic monomer, from 0.5 to 20% by weight of an ethylenically unsaturated amine as a monomer for introducing into the copolymer a gelling of the copolymer, and at most 40% by weight of a copolymerizable monomer with them. 8 Coating composition for newsprint,   according to any one of claims 1 to 5,   characterized in that the amphoteric copolymer latex is a latex obtained by copolymerization, with the aid of an amphoteric surfactant, of a monomer mixture comprising from 20 to 50% by weight of an aliphatic diene monomer   conjugate, from 10 to 74% by weight of a vinyl monomer   from 0.5 to 20% by weight of an ethylenically unsaturated acidic monomer, and at most 40% by weight of a   monomer copolymerizable with them.