KR101219221B1 - Latex for cotating paper, paper liquid and color paper - Google Patents

Abstract

The present invention relates to a latex for paper coating, a paper coating liquid and color paper, including two kinds of styrene-butadiene-based latexes having different glass transition temperatures, improving the adhesive strength of the coated paper and the adhesion of the latex, and at the same time the rheol of the coating color. It is possible to provide latex for paper coating, paper coating liquid and colored paper which can improve the lodge.

Paper coating latex according to the present invention, the paper coating liquid containing it and the paper coated with the paper coating liquid by using a paper coating latex that can simultaneously improve the printing gloss and ink drying speed while maintaining the adhesion and white paper gloss It improves the adhesion strength and adhesiveness of coated paper and improves the rheology of coating color by including two kinds of styrene-butadiene-based latexes with different glass transition temperature. It has an advantage that can be made.

Paper coating latex, styrene-butadiene-based latex, glass transition temperature, adhesive strength, adhesiveness, rheology

Description

Latex for paper coating, paper coating liquid and color paper {LATEX FOR COTATING PAPER, PAPER LIQUID AND COLOR PAPER}

The present invention relates to a latex for paper coating, a paper coating liquid, and color paper, and more particularly, to improve adhesion strength and stickiness of coated paper, including two kinds of styrene-butadiene-based latexes having different glass transition temperatures. At the same time, the present invention relates to latex for paper coating, paper coating liquid and color paper which can improve the rheology of coating color.

In general, coated paper is prepared by coating inorganic pigments such as clay, calcium carbonate and titanium dioxide on paper, and at this time, natural binders such as sane and starch and artificial binders such as styrene-butadiene-based latex, polyvinyl alcohol, and acrylic latex are adhesive. It is used as, and various additives, such as a dispersing agent, a thickener, and a water-resistant agent, are used together. Of these, the binder has a great influence on the quality of the coated paper.

The latex for paper coating, which serves as an adhesive of coated paper, is required to have the adhesiveness, gloss, and printability of ink drying speed, and the adhesive force is required to have stronger adhesion as offset printing is recently accelerated. It is important to maintain a clean printing appearance in order to prevent peeling of the pigment and peeling from the coating layer against strong mechanical force on the surface of the pigment coated paper during printing.

The gloss is an important physical property that can increase the commerciality of printing paper and pursue high quality. This gloss can be divided into white gloss of coated paper and print gloss after printing, and both of them have a beautiful appearance.

In order to increase the gloss of the white paper, a method such as controlling the glass transition temperature, particle diameter, etc. of the latex, or lowering the latex content in the coating solution may be used, but in this case, there is a problem in that the adhesive strength is lowered. In addition, in order to increase the gloss of printing, it is necessary to increase the chemical resistance of the latex for paper coating, and to maintain a long residence time on the surface until the printed surface is stably arranged.

In addition, the ink drying speed is an important property of the coating liquid and affects the printing speed and printing appearance. In the case of multicolor printing, it is generally overprinted by four colors such as black, blue, red, and yellow. As the printing speed increases, the time interval until the next color printing becomes shorter, and a faster ink drying speed is required. In addition, when the ink is not sufficiently dried and the next step is passed, there is a problem that a printing mottle or smearing may occur.

This ink drying speed is slowed down when the paper coating latex interferes with the penetration of the printing ink, so it is advantageous to be made of a material having low chemical resistance. Too high an ink drying speed is advantageous in the printing process but causes a problem of poor printing gloss.

As described above, the printing gloss is closely related to the appearance of printing, and the ink drying speed affects the printing speed and the printing mold, so it is very difficult to simultaneously improve the printing gloss and the ink drying speed in inversely proportional properties.

In addition, latex adhesiveness is also regarded as an important property that can cause equity problems that may occur due to the tearing of the surface of the coated paper during printing, which not only improves print gloss and print drying speed, but also improves coated paper adhesion and latex adhesion. More research on the technology that can be done.

The inventors of the present invention while continuing to study to solve the problems of the prior art as described above, since the adhesion of the latex is greatly affected by the glass transition temperature, the physical properties of the coat by the latex prescription that controlled the range of glass transition temperature The present invention has been completed by finding that a change can be made and the adhesiveness of the coated paper can be improved while improving the adhesiveness.

That is, an object of the present invention is to improve the adhesive strength of the coated paper at the same time to improve the adhesiveness and to improve the white paper gloss, print gloss and ink drying speed at the same time and the paper coating latex and paper coating liquid therefrom and the color produced using the same I'm trying to provide paper.

In order to achieve the above object, the paper coating latex of the present invention is a styrene-butadiene-based latex i) a glass transition temperature (Tg) of 20 to 30 ℃, and ii) a glass transition temperature (Tg) of -10 to It is characterized by comprising a latex, which is 0 ℃.

In addition, the paper coating liquid of the present invention

Paper coating latex, including a pigment, and a thickener, the paper coating latex is characterized in that using the above-described paper coating latex.

In addition, the color paper of the present invention is characterized in that the paper coating liquid is coated.

Hereinafter, the present invention will be described in detail.

The paper coating latex of the present invention is characterized in that it comprises a styrene-butadiene-based latex having a glass transition temperature of 20 to 30 ℃ and a styrene-butadiene-based latex having a glass transition temperature of -10 to 0 ℃. Such a glass transition temperature of the latex is an important parameter not only in adhesion but also in the adhesive strength of the coated paper. Since the temperature is within the range of -10 to 0 ° C., improved adhesive strength can also be expressed together, which is preferable.

The styrene-butadiene-based latex used in the present invention grafts butadiene-based monomers, vinyl cyanide-based monomers, styrene-based monomers, ethylenically unsaturated monomers, and vinyl-based monomers copolymerizable with the monomers on styrene-butadiene-based seeds. It can be prepared by.

Specifically, 0.1 to 60 wt% of butadiene monomers, 0.1 to 10 wt% of vinylcyanic monomers, 39.6 to 99.6 wt% of styrene monomers, 0.1 to 20 wt% of ethylenically unsaturated acid monomers, and the styrene-butadiene seed, 0.1 to 30% by weight of a vinyl monomer copolymerizable with the monomer is prepared by graft polymerization of 1 to 4 ply shells.

Among the styrene-butadiene-based latex prepared in this way, the glass transition temperature satisfies the range of 20 ~ 30 ℃, but is not limited to this, Lutex910 made by LG Chem, etc. Also, the glass of styrene-butadiene-based latex Examples of the product satisfying the transition temperature within the range of -10 to 0 ° C include, but are not limited to, Lutex760 manufactured by LG Chem. In addition, the compounding ratio of the latex having the two glass transition temperature is a coat ratio of latex having a glass transition temperature of 20 ~ 30 ℃ and latex having a glass transition temperature of -10 ~ 0 ℃ range of 7: 3 to 9: 1 It is preferable considering both the adhesive strength of the paper and the adhesive strength of the latex, of which the most efficient ratio is 8: 2.

In addition, the butadiene-based monomer may be a conjugated diene compound such as 1,3-butadiene, isoprene, chloroprene, or pyrrylene.

The butadiene-based monomer is preferably included in 0.1 to 60% by weight based on the total 100% by weight of the monomer contained in the styrene-butadiene-based latex, when the content is less than 0.1% by weight the copolymer is too hard There exists a problem that rigidity falls when it exceeds 60 weight%.

The vinyl cyan monomer has excellent chemical resistance compared to other monomers included in latex, thereby improving printing glossiness.

The vinyl cyan monomer can be used all commercially available butadiene monomer used in the production of styrene-butadiene-based latex, which is known enough to be readily available to those skilled in the art. Specifically, the vinyl cyan monomer may be acrylonitrile, methacrylonitrile or ethacrylonitrile.

The vinyl cyan-based monomer is preferably included in 39.6 to 99.6% by weight based on the total 100% by weight of the monomer contained in the styrene-butadiene-based latex, when the content is less than 39.6% by weight can not be obtained a sufficient hardness If there is more than 99.6% by weight, there is a problem in adhesion and film formation.

The styrene-based monomer functions to impart proper hardness to the polymerized latex. The styrene-based monomers are all commercially available conventional styrene-based monomers used to prepare styrene-butadiene-based latex, which is known to those skilled in the art can be easily purchased and used.

Specifically, the styrene monomer may be styrene, alphamethylstyrene, alphaethylstyrene, paramethylstyrene, vinyltoluene, 4-chlorostyrene, or 3,4-dichlorostyrene.

The styrene-based monomer is preferably included in 0.1 to 10% by weight based on the total 100% by weight of the monomer contained in the styrene-butadiene-based latex, when the content is less than 0.1% by weight latex stability may be lowered There exists a problem that print gloss falls when it exceeds 10 weight%.

The ethylenically unsaturated acid-based monomer serves to improve the adhesion of the polymerized latex and improve the stability of the latex particles. The ethylenically unsaturated acid monomers include unsaturated carboxylic acids such as methacrylic acid, acrylic acid, itaconic acid, crotonic acid, fumaric acid, maleic acid and the like; Or unsaturated polycarboxylic acid alkyl esters having at least one carboxyl group such as itaconic acid monoethyl ester, fumaric acid monobutyl ester, maleic acid monobutyl ester and the like can be used.

The ethylenically unsaturated acid-based monomer is preferably included in 0.1 to 20% by weight based on a total of 100% by weight of the monomer contained in the styrene-butadiene-based latex, when the content is less than 0.1% by weight to improve the stability and adhesion of the latex There exists a problem, and when it exceeds 20 weight%, there exists a problem that polymerization stability falls.

In addition, the vinyl monomer copolymerizable with the monomers serves to impart moderate hardness to the polymerized latex and improve film forming ability.

The copolymerizable vinyl monomers include unsaturated carboxylic acid alkyl esters such as methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, butyl acrylate or butyl methacrylate; Unsaturated carboxylic hydroxyalkyl esters such as beta-hydroxyethyl acrylate, beta-hydroxypropyl acrylate, beta-hydroxyethyl methacrylate, and the like; Or aromatic vinyl monomers such as alpha-methyl styrene, vinyltoluene or para-methylstyrene.

The copolymerizable vinyl monomer is preferably included in 0.1 to 50% by weight based on the total 100% by weight of the monomer contained in the styrene-butadiene-based latex, when the content is less than 0.1% by weight polymerization stability is deteriorated There exists a problem that printing gloss falls when it exceeds 50 weight%.

Styrene-butadiene-based latex as described above is preferably included in the paper coating latex 0.1 to 99.9% by weight, more preferably 30 to 70% by weight. If the content is less than 0.1% by weight or more than 99% by weight, the physical property balance required by the latex is lowered, which may cause problems, as well as the chemical resistance and the gloss and adhesion of the ink is lowered. have.

In addition to the styrene-butadiene-based latex described above, butadiene-vinyl cyan-based latex may be added as a binder. Butadiene-vinyl cyanate latexes that can be used include butadiene-vinyl cyanate latexes containing 39.6 to 99.6% by weight of vinyl cyanide monomers, butadiene-based monomers, vinyl cyanide-based monomers, styrene-based monomers, ethylene It may be prepared by grafting the unsaturated unsaturated monomer and the vinyl monomer copolymerizable with the monomers.

The styrene-butadiene seed, butadiene monomer, vinyl cyan monomer, styrene monomer, ethylenically unsaturated acid monomer, and the vinyl monomer copolymerizable with the monomer are used in the styrene-butadiene-based latex. The same ones used in eye latex can be used. Styrene-butadiene-based latex prepared by grafting the monomers to the styrene-butadiene seed is preferably contained in 0.1 to 99.9% by weight, more preferably 30 to 70% by weight in the latex for paper coating It is good. If the content is less than 0.1% by weight or more than 99% by weight, the physical property balance required by the latex may be lowered, which may cause a problem, and the ink drying speed may be slowed.

In addition, a chain transfer agent may be further included to control molecular weight, gel content, or gel structure during polymerization of styrene-butadiene seed, styrene-butadiene latex, or butadiene-vinylcyanate latex used in the present invention. .

The chain transfer agent may be an alkyl mercaptan having one thiol in one molecule such as n-dodecyl mercaptan or t-dodecyl mercaptan; Or 1,5-pentanedithiol, 1,6-hexanedithiol, 2-ethylhexyl-3-mercaptopropionate, butyl-3-mercaptopropionate, dodecyl-3-mercaptopropionate , Ethyl-2-mercaptopropionate, ethyl-3-mercaptopropionate, methyl-3-mercaptopropionate, pentaerythritol tetrakis (3-mercaptopropionate), 2-ethylhexyl Two in one molecule, such as mercaptoacetate, ethyl-2-mercaptoacetate, 2-hydroxymethyl-2-methyl-1,3-propanediol, or pentaerythritol tetrakis (2-mercaptoacetate) The polyfunctional chain transfer agent which has the above thiol can be used.

The chain transfer agent is preferably included in an amount of 0.1 to 5.0 parts by weight, more preferably 0.1 to 3.0 parts by weight, based on 100 parts by weight of the total monomers used. If the content is less than 0.1 parts by weight, there is a problem in that the final paper latex for the molecular weight, gel content and gel structure is not suitable, if the content exceeds 5.0 parts by weight the reaction rate and the stability of the reaction may be lowered have.

In addition, additives such as a polymerization initiator, an emulsifier, an electrolyte, and the like commonly used in the polymerization of styrene-butadiene seed, butadiene-vinylcyanate latex, or styrene-butadiene-based latex may be used. This is known so that it can be easily purchased and used by those skilled in the art. In addition, the polymerization method is not particularly limited, but is preferably emulsion polymerization. The gel content of the paper coating latex of the present invention prepared as described above is preferably from 20 to 99%, more preferably from 50 to 95%, It is preferable that glass transition temperature is -20-30 degreeC, More preferably, it is -5-25 degreeC.

In addition, the average particle diameter of the paper coating latex is preferably 80 to 200 nm, more preferably 100 to 150 nm. If the average particle diameter is less than 80 nm, there is a problem that low shear fluidity is increased, and white gloss and ink drying speed may be reduced. If it exceeds 200 nm, high shear fluidity may be increased and printing gloss and adhesion may be reduced. There is a problem.

Furthermore, it is possible to manufacture a paper coating liquid containing the latex for paper coating, specifically, in a paper coating liquid comprising a latex for paper coating, a pigment, and a thickener, the latex for paper coating includes the latex for paper coating. Clay, calcium carbonate or a mixture thereof may be used as the pigment, and an acrylic thickener may be used as the thickener. In this case, when the clay and calcium carbonate are mixed as the pigment, the amount of the clay and the calcium carbonate used in the weight ratio of 1: 9 to 3: 7, more preferably 2: 8, not only reduces the cost of the coating color but also coats It is preferable in view of improving the whiteness and fluidity of the paper.

In particular, it is preferable to blend 7 to 15 parts by weight of the above-described styrene-butadiene-based latex, 2 to 6 parts by weight of coating starch, and 0.1-1.0 parts by weight of an acrylic thickener based on 100 parts by weight of the pigment, which is a property of the coating color. And various physical properties, such as the physical properties of the coated paper and the printability of the coated paper using this formulation. In particular, if the content of the latex is too small, there is a problem that the surface strength is lowered. On the contrary, if the content is too high, the cost of the coating color may increase, and backing may occur due to a decrease in drying speed during printing.

Likewise, when the amount of the starch for coating is added, the surface strength may be lowered, and excessively, fluidity may be caused due to an increase in the coating color cost and an increase in the viscosity, similar to latex. In the case of acrylic thickener, if the input amount is too small or too high, the viscosity of the coating color may be too low or too high, which may greatly affect the workability of the coating process. Therefore, it is necessary to optimize the dosage of each additive. In addition, the dispersant may be further added within the range of 0.05-0.2 parts by weight, 0.05-0.2 parts by weight of caustic soda, 0.1-1.0 parts by weight of lubricant and 0.1-1.0 parts by weight of water-resistant agent.

Furthermore, the color paper coated with the above-described paper coating liquid can improve the printing gloss and ink drying speed at the same time, while maintaining the adhesion and the white paper gloss, as described in the following examples.

Paper coating latex according to the present invention, the paper coating liquid containing it and the paper coated with the paper coating liquid by using a paper coating latex that can simultaneously improve the printing gloss and ink drying speed while maintaining the adhesion and the white paper gloss Both printing gloss and ink drying speed are improved to improve the adhesive strength of coated papers, including two types of styrene-butadiene-based latexes with different glass transition temperature, improve adhesion, and improve the adhesion of coating color. Has the advantage of improving the performance.

Hereinafter, preferred examples are provided to help understanding of the present invention, but the following examples are merely to illustrate the present invention, and the scope of the present invention is not limited to the following examples.

Example  1-4 and Comparative example  1-2

(Manufacture of latex for paper coating)

As a latex for the coating was prepared in the compounding ratio shown in Table 1 and then stirred to avoid bubbles. At this time, the latex was mixed based on the solid weight.

division Example 1 Example 2 Example 3 Example 4 Comparative Example 1 Comparative Example 2 Styrene-butadiene-based latex (wt%) Lutex910
(Tg 24 ℃) 80 60 40 20 90 10 Lutex760
(Tg -5 ℃) 20 40 60 80 10 90

The basic physical properties of the Lutex910 are summarized in Table 2 below.

Evaluation item unit Lutex910 One. pH - 6.5 to 7.5 2. Solid Concentration % 49.5 ~ 50.5 3. Viscosity cps Max. 300 4. Specific gravity - 1.00 ~ 1.05 5. Surface tension dyne Of cm 40-50 6. Particle diameter Å 1100-1300 7. Glass transition temperature ℃ 20 to 30 8. Gel content % 75 to 85

In addition, the basic physical properties of the Lutex760 are summarized in Table 3 below.

Evaluation item unit Lutex760 One. pH - 7.5-8.5 2. Solid Concentration % 49.5 ~ 50.5 3. Viscosity cps Max. 400 4. Specific gravity - 1.00 ~ 1.05 5. Surface tension dyne Of cm 35-45 6. Particle diameter Å 700-900 7. Glass transition temperature ℃ -10 to 0 8. Gel content % 77-87

The solids content, glass transition temperature, particle size, and gel content values of the latex for paper coatings prepared by each of Examples 1-4 and Comparative Examples 1-2 were summarized in Table 4 below.

Evaluation item unit Example  One Example  4 One. pH - 7.0 to 8.0 7.0 to 8.0 2. Solid Concentration % 49.5-50.5 49.5 ~ 50.5 3. Viscosity cps Max. 300 Max. 300 4. Specific gravity - 1.00 to 1.05 1.00 ~ 1.05 5. Surface tension dyne Of cm 40-50 35 to 45 6. Particle diameter Å 1100-1300 700 to 900 7. Glass transition temperature ℃ 15 to 25 -5 to 5 8. Gel content % 75 to 85 77-87

Evaluation item unit Example  3 Example  4 One. pH - 7.0 to 8.0 7.0 to 8.0 2. Solid Concentration % 49.5-50.5 49.5 ~ 50.5 3. Viscosity cps Max. 300 Max. 300 4. Specific gravity - 1.00 to 1.05 1.00 ~ 1.05 5. Surface tension dyne Of cm 37 to 47 35 to 45 6. Particle diameter Å 800 to 1000 700 to 900 7. Glass transition temperature ℃ 8 to 18 -5 to 5 8. Gel content % 76 to 86 77-87

Evaluation item unit Comparative example  One Comparative example  2 One. pH - 7.0 to 8.0 7.0 to 8.0 2. Solid Concentration % 49.5-50.5 49.5 ~ 50.5 3. Viscosity cps Max. 300 Max. 300 4. Specific gravity - 1.00 to 1.05 1.00 ~ 1.05 5. Surface tension dyne Of cm 40-50 35 to 45 6. Particle diameter Å 1100-1300 700 to 900 7. Glass transition temperature ℃ 17 to 27 -7 to 3 8. Gel content % 75 to 85 77-87

(Paper Coating Color Prescription)

The formulation of the coating color for the prepared paper coating latex is shown in Table 5 below.

Coated collar prescription Addition amount (part by weight *) Clay 20.0 Calcium carbonate 80.0 Starch for coating 4.0 Acrylic thickener 0.2 Latex (Lutex910: Lutex760 = 80:20 combination) 11.0 Caustic soda 0.15 Dispersant 0.12 slush 0.51 Water resistant 0.50 Coating Color Solids Concentration 67.0%

* Addition of thickener, latex, and other additives based on 100 parts by weight of calcium carbonate and clay.

The paper coating solution thus prepared was coated on the coated paper under the conditions described in Table 6 below.

coating Rod Coating, No 5 dry Oven, 105 ° C., 30 seconds Calenda Super calendar, 60 ° C, 65 kg / cm, 4 m / min, 2 passes Paper Commercial paper (Basic weight 70 gsm)

Specifically, the coated paper using the latex for paper coating of Example 1 was coated using an MLC lab applicator, and then calendered using steel and curtain rolls, and the adhesion resistance of the coated paper and the coating color properties (shear viscosity, water retention) , Coated paper properties (smoothness, air permeability, gloss), printability and the like were measured by the following method, and the results are shown in Table 7 below.

* Adhesion Resistance-5-6 g / m ² of latex prepared on a paper base paper having a basis weight of 70 gsm was coated. It was passed by adjusting the temperature (40 ~ 80 ℃), pressure (300 ~ 600 psi) while calendaring using a sampling calendar prepared by placing black paper on both sides of the coated paper. After passing, the coated paper was peeled off and the black stake separated from the coated paper was visually evaluated according to the 10-point method.

A) Low shear viscosity: evaluated using a Brookfield viscometer.

B) High shear viscosity: evaluated using Hercules High-shear viscometer.

C) conservatism: evaluated using AA-GWR.

D) pH: evaluated using a pH meter.

ㅁ) smoothness and air permeability: was measured using PPS (Parker Print Surf).

Viii) Gloss: Measured using a gloss meter.

S) Printability: measured by RI printability tester.

ㅇ) White paper gloss: Glossiness of coated paper using latex for paper coating of Examples 1 to 10 and Comparative Examples 1 to 3 before printing using an optical gloss meter (HUNTER type, 70 to 75 °) Were measured and their average value was calculated.

Printing gloss: printed on coated paper using the latex for paper coating of Examples 1 to 10 and Comparative Examples 1 to 3 in an RI printing machine, and after 24 hours, the gloss of various parts of the coated paper was measured, and the average value thereof was measured. Calculated.

Dry pick: The adhesive strength was evaluated using an RI printing press using magenta inks with different viscosities.

Wet pick: We used RI printing machine and magenta ink, but wetted the surface of coated paper with wet water and evaluated the adhesive strength.

I) Ink set-off: The ink drying speed of the coated paper surface was measured using cyan ink.

2) color trapping: After printing yellow ink first, cyan ink was printed to measure the color density after printing.

Water ink receptivity: Color density was measured after printing using black ink in a state of a small amount of damp water.

Properties Embodiment 4 of the present invention Adhesive Resistance SB Latex ** High Adhesion Standard SB Latex *** Remarks Adhesion Resistance 9 10 3 10 dot method Low shear viscosity (cPs) 994 1152 1030 High shear viscosity (cPs) 34.3 32.7 34.5 Coating color pH 9.08 8.24 9.09 Water retention (g / m ² ) 136 138 130 Smoothness (㎛) 1.01 0.98 0.98 Air permeability (sec.) 2455 2319 2578 White paper gloss (%) 70.7 70.6 70.1 Print Gloss (%) 92.2 94.5 92.8 Dry pick 4.4 3.8 4.5 5-point method Wet pick 4.5 4.0 4.0 Ink set-off 4.1 4.0 4.0 2 Color trapping 4.1 4.0 4.0 Water Ink receptivity 4.5 4.5 4.5

** SB latex based on adhesion resistance: LG Chem by Lutex910

*** High Adhesion Standard SB Latex: LG Chemical Product Lutex760

As shown in Table 7, in the case of Example 4 presented as an improved sample of the present invention, it showed almost similar physical properties to the conventional styrene-butadiene-based latex having excellent adhesion resistance with nine points of adhesion resistance, and the adhesive strength was also the case of the present invention. According to the present invention, it was confirmed that the adhesiveness and the adhesive strength were excellent according to the present invention because the level of 4.4 was similar to that of the high-adhesive styrene-butadiene-based latex as 4.4.

Claims (10)

Styrene-butadiene-based latex in the styrene-butadiene-based seed 0.1 to 60% by weight of butadiene monomer, 0.1 to 10% by weight vinyl cyanide monomer, 39.6 to 99.6% by weight styrene monomer, 0.1 to 20% by weight ethylenically unsaturated acid monomer , And a copolymer obtained by grafting 0.1-30 wt% of monomers copolymerizable with the monomers into 1 to 4-ply cells, A latex for paper coating comprising i) a latex having a glass transition temperature (Tg) of 24 ° C., and ii) a latex having a glass transition temperature (Tg) of −5 ° C., in a weight ratio of 7: 3 to 9: 1. delete delete delete The method of claim 1, Latex for paper coating, characterized in that the average particle diameter of the paper coating latex is in the range of 80 to 200 nm. Including latex for paper coatings, pigments, and thickeners, The paper coating latex is a paper coating liquid, characterized in that using the paper coating latex according to claim 1. The method of claim 6, The pigment is paper coating liquid, characterized in that using clay, calcium carbonate or a mixture thereof. The method of claim 7, wherein The clay and calcium carbonate is a paper coating liquid, characterized in that it comprises a weight ratio of 1: 9 to 3: 7. The method of claim 6, The paper coating liquid is a paper coating liquid, characterized in that the formulation of 7 to 15 parts by weight of latex, 2 to 6 parts by weight of coating starch, 0.1 to 1.0 parts by weight of an acrylic thickener based on 100 parts by weight of pigment. The color paper coated with the paper coating liquid of any one of Claims 6-9.