KR20040010680A - Pigment composition - Google Patents

Abstract

The present invention relates to an aqueous pigment particle slurry or dispersion comprising an amphoteric polymer at least partially adsorbed onto the pigment particles as a dispersant, wherein the viscosity is doubled when the slurry or dispersion is elevated from 20 ° C. to 100 ° C. It is characterized by exhibiting temperature dependent viscosity properties in an increasing manner. The invention also relates to a process for producing a slurry or dispersion, to a coating color composition and to a process for the preparation thereof, to a method for producing a coated paper or board, and to a paper or board produced by this method.

Description

Pigment Composition {PIGMENT COMPOSITION}

Paper is often coated to give it the necessary properties. For example, a surface suitable for giving improved gloss or for printing is often desirable.

The paper surface needs to have a certain gloss to print and aesthetically pleasing. However, most of the paper is reduced during calendering, resulting in a more flexible, flexible and less rigid paper structure. However, the secondary effect of excessive calendering is not always desirable to achieve gloss.

Traditional coating color compositions for paper include pigment particle slurries or dispersions with various additives. Provide a pigment particle slurry or dispersion with one or more dispersants and mix the slurry or dispersion with additives such as binders (latex or starch) and rheological agents such as co-binders or thickeners (eg CMC) The composition is usually prepared. In addition, brighteners and other conventionally used additives such as pH adjusters, foam inhibitors, lubricants, preservatives, and anti-dissolution agents may be included.

The use of a high solids content coating color requires less energy to dry the coated paper and reduces the tendency of water and binders to migrate on the paper web. The entire coating process is therefore faster.

Pigment particles are small, weakly charged particles with an average diameter of 0.2-1 μm. When suspended in water, particles tend to agglomerate if they attract more force than repulsion. Therefore, when the amount of solid material in the pigment slurry is increased, there is a problem of aggregation or dispersion of the pigment. Therefore, addition of one or more dispersants is required. Commonly used dispersants are mainly negatively charged polymers such as polyacrylic acid (PAA) and polyphosphate. As a rule, the addition of dispersants lowers the viscosity to a certain level, after which the addition of dispersants greatly increases the viscosity due to the inherent viscosity of the dispersant. Thus there is an optimal dispersant concentration corresponding to the minimum viscosity of the pigment slurry at a given solid material level. This concentration in a given dispersant is very dependent on the type of pigment used.

In addition, when a high charge dispersant (such as PAA) is used in large quantities, the resulting coating broke contains a high level of charged species, so when re-introduced to the wet end of the paper machine, Will interfere with function.

Many polymers, especially uncharged polymers, in solution have a temperature dependent viscosity such that the viscosity of the solution increases significantly above a certain temperature causing the polymer to gel or precipitate due to the association of the polymer chains. The greatly increased viscosity is due to hydrophobic interactions between the polymer chains caused by the gradual breakdown of the water shell around the polymer. As the temperature increases further, hydrogen bonds continue to be removed, releasing water molecules. Larger aggregates of associated polymers are formed and the total area of polymer chains exposed to water is minimized. In the case of non-charged polymers, the addition of surfactants can raise the temperature at which a large increase in viscosity is initiated, so that the non-charged polymer molecules behave as charged molecules thanks to the attached surfactant ions, e.g., less than 100 ° C. There is no increase in viscosity.

The use of polymers whose viscosity rises when heated as a thickening agent in paper coating compositions is disclosed in US Pat. Nos. 6117491 and 6123996. Similar compositions are disclosed in EP-A-359349.

The present invention relates to an aqueous pigment particle slurry or dispersion comprising an amphoteric polymer as a dispersant and a method for producing the same. The invention also relates to a coating color composition and a method of making the same, a method of making a coated paper or board, and a paper or board made by the method.

It is an object of the present invention to provide pigment slurry or dispersions having a low viscosity but high solids content.

It is also an object of the present invention to provide a coating color composition based on a slurry or dispersion that is rapidly immobilized on a paper or cardboard surface.

It is also an object of the present invention to provide a coated paper or paperboard manufacturing process having a high gloss or surface suitable for printing without excessive calendering.

One aspect of the invention relates to pigment particle aqueous slurries or dispersions comprising an amphoteric polymer at least partially adsorbed onto pigment particles as a dispersant, wherein the slurry or dispersion has a temperature of 20 ° C. to 100 ° C., in particular When the temperature rises from 80 ° C., more than 40 ° C. to 70 ° C., the viscosity increases by 2 times, in particular 5 times, and even more than 10 times. Continued heating to higher temperatures destabilizes the system and eventually causes excessive coagulation.

The solids content of the slurry or dispersion is at least 60% by weight, in particular at least 70% by weight. The upper limit depends only on the viscosity and should be low enough so that the slurry or dispersion can be pumped below 20 ° C, in particular below 30 ° C. Brookfield viscosities below 20 ° C. are 50-1000 mPa, in particular 50-200 mPa. In fact, it is difficult to provide a slurry or dispersion having a solids content above 80% by weight.

Pigment particles are weakly charged inorganic particles such as clay (eg kaolin), TiO ₂ , calcium carbonate or mixtures thereof. The use of clay can easily give gloss to paper. Calcium carbonate, on the other hand, is cheaper and has a brighter color. Calcium carbonate can be used in the form of precipitated calcium carbonate (PCC) or ground calcium carbonate (GCC) (eg ground limestone, marble or chalk). The present invention has been found to be particularly advantageous when PCC is used as a pigment particle which is generally difficult to disperse due to a narrow particle size distribution.

The average particle diameter of the pigment particles is 0.1-2 탆, especially 0.2-1 탆.

Dispersants are reagents that participate in the deagglomeration process of the pigment particles. The dispersant thus reduces the energy required to separate the pigment into discrete particles, providing stability to prevent aggregation during storage and reducing viscosity at high solids content. In contrast to reagents classified as surfactants, dispersants have a small effect on surface tension, wetting and foaming, but provide high de-agglomeration. In contrast to the thickening agent completely soluble in water, the dispersant of the present invention is at least partially adsorbed onto the pigment particles.

Amphoteric polymers used as dispersants have an average molecular weight of 2000-200000, in particular 3000-100000, even 5000-20000.

Dispersants to be used in the present invention are amphoteric polymers having hydrophilic and hydrophobic groups as opposed to PAA, which have a different structure from PAA. The hydrophilic group is selected from the negatively charged portion, PEO / PPO (polyethylene oxide / polypropylene oxide) or mixtures thereof. At least some of the hydrophilic groups in the preferred polymers are charged and are selected from inorganic or organic acid residues such as sulfonates, phosphonates, carboxylates or mixtures thereof. Preferred polymers are copolymers comprising hydrophilic and hydrophobic moieties with residues alternating along the backbone, in particular charged hydrophilic attachment groups located along the backbone. Hydrophobic moieties are C ₄ -C ₂₀ , in particular C ₄ -C ₁₈ carbon chains. Hydrophilic moieties comprise PEO / PPO chains or segments along the polymer backbone. Hydrophilic residues comprise 5-50, in particular 20-50 EO / PO units.

It has been found that the amphoteric polymers of the present invention show no significant increase in viscosity at 20-100 ° C. when partially adsorbed onto pigment particles. When the polymer is charged, some of the charge is neutralized by adsorption on the surface of the pigment particles, but thanks to the residual charge, the polymer is believed to maintain the dispersing action. Thus surface adsorption through partial electrical neutralization and retention of charge in the accessory chains is a feature of the polymers of the present invention. However, amphoteric polymers, which are effective as dispersants and exhibit such temperature dependent viscosity properties even when at least partially adsorbed onto the pigment particles, can also be used in the present invention, which exhibit a significant increase in viscosity at 20-100 ° C.

At temperatures below 20 ° C., the hydrophilic and hydrophobic tails of the polymer emerge from the surface of the pigment particles and act to stabilize electrostatic or steric hindrance. Thanks to this stabilization the polymers of the present invention are less sensitive to the presence of salts than polymers that rely only on stabilization through degradation.

In one aspect the dispersant is an acrylic ester copolymer having an accessory hydrophobic chain, a hydrophilic chain and having phosphonic acid or carboxylic acid as the anion. The accessory hydrophobic chain is a C ₄ -C ₂₀ , in particular a C ₄ -C ₁₈ carbon chain. The hydrophilic chain comprises alkylene oxide groups, in particular 2-50, in particular 10-30 EO or PO units. Preference is given to EO or to alkylene oxide groups having virtually only EO groups. Phosphonate groups in the polymer result in strong adsorption to the calcium carbonate particles.

In another aspect the dispersant is selected from hydrophobically modified carboxymethyl cellulose (HM-CMC). Preferred HM-CMC polymers are obtained by the process of reacting alkali metal cellulose with at least three alkylating reagents A, B, C;

At least one reagent A is selected from haloacetic acid, alkali metal haloacetate, alkali metal vinylsulfonate and vinyl sulfonic acid;

At least one reagent B has the formula R ^1- (OCH ₂ CH (R ² )) _n -P, R ¹ is a C ₂ -C ₇ group, R ² is a hydrogen or methyl group, n is 0-2 and P is Glycidyl ether groups, 3-halo-2-hydroxypropyl ether groups, 1,2-epoxy groups or halides;

At least one reagent C has the formula R ^3- (OCH ₂ CH (R ² )) _m -P, R ³ is a C ₈ -C ₃₀ group, m is 0-10 and R ² and P have the same meaning as above . Such HM-CMC polymers are detailed in WO 98/56825.

Polyurethane based copolymers disclosed in US4096127 or US4777224 can be used as dispersants, such as polyurethane copolymers having at least one carboxylic acid moiety as the anionic moiety. In addition, copolymers based on alpha olefin / maleic anhydride as disclosed in US Pat.

Polymers used as dispersants may be based on materials capable of producing copolymers having similar hydrophilic and hydrophobic moieties and anionic attachment groups may contain suitable acidic functionalities, such as hydrophobically modified carboxymethyl cellulose, to charge along the backbone. Natural polymers, such as carbohydrates that have been modified with introduction of a group or grafted with hydrophobic and hydrophilic tails.

Slurries or dispersions may contain one or more amphoteric polymers in combination with one or more other dispersants.

The slurry or dispersion has a solids content of 40-80, in particular 60-75% by weight, most of which, in particular substantially all, consist of pigment particles. It also comprises 0.1-4, in particular 0.1-2% by weight of one or more amphoteric polymers as a dispersant relative to the dry pigment. The water content is 20-60, especially 25-40% by weight based on the dry pigment. The content of the other components is less than 0.5% by weight, in particular less than 0.1% by weight relative to the dry pigment.

The present invention also relates to a slurry or dispersion method comprising the steps of mixing a pigment particle, water and an amphoteric polymer adsorbed at least in part on the pigment particle to obtain a slurry or dispersion exhibiting temperature dependent viscosity properties.

The invention also relates to a coating color composition comprising at least one additive selected from binders, co-binders, rheology modifiers, foam inhibitors, varnishes, pH adjusting agents, lubricants, preservatives and anti-dissolution agents and the slurry or dispersion described above. The coating color composition is characterized by a temperature dependent viscosity. Thus, when the temperature rises from 20 ° C. to 100 ° C., in particular from 30 ° C. to 80 ° C., even from 40 ° C. to 70 ° C., the viscosity increases by at least two times, in particular at least five times and even more than ten times.

The property of showing a large viscosity increase at 20 ° C. to 100 ° C. is dependent on the presence of the amphoteric polymer at least partially adsorbed on the pigment particles.

The solids content of the coating color composition is at least 50% by weight, in particular at least 60% by weight. The upper limit depends only on the viscosity and should be low enough to allow the composition to be applied to the surface of paper or paperboard below 20 ° C, in particular below 30 ° C. Brookfield viscosity below 20 ° C. is 50-5000 mPa, in particular 50-3000 mPa. In fact, it is difficult to provide a slurry or dispersion having a solids content above 80% by weight.

The amphoteric polymer is present in the coating color composition in an amount of 0.05-10 pph, especially 0.1-5 pph, even 0.1-2 pph, based on 100 pph (part per hundred) pigment particles. The amount of can also be lower than the above figures and higher amounts are required for high solids compositions. The amount of suitable dispersant can be determined by one of ordinary skill in the art by routine experimentation.

The composition may comprise 5-25 pph of binder. Traditional binders such as starch, latex, proteins, polyvinyl alcohol and mixtures thereof can be used.

The composition may comprise 0.1-5 pph co-binder or rheology modifier. Traditional co-binders such as carboxymethyl cellulose (CMC), other cellulose derivatives, alkali swellable polyacrylates and mixtures thereof can be used.

The composition may comprise 0.1-5 pph of other additives. Conventional additives such as antifoams, dispersants (in addition to amphoteric polymers at least partially adsorbed onto pigment particles), brighteners (OBAs), pH adjusters, lubricants, preservatives and dissolution inhibitors can be used. These additives are known and can be easily selected by those skilled in the art.

Preferred compositions of the invention include 0.1-4 pph, especially 0.1-2 pph, of an amphoteric polymer dispersant for 100 pph pigment particles, calculated on a dry solids content based on weight; 5-25 pph, in particular 10-15 pph; 0.1-4 pph, in particular 0.5-2 pph co-binder or rheology modifier; Other additives of 0.1-5 pph, in particular 0.1-2 pph.

The invention also includes mixing a pigment particle slurry or dispersion with at least one additive selected from foam inhibitors, binders, co-binders, rheology modifiers, varnishes (OBAs), pH adjusters, lubricants, preservatives and dissolution inhibitors. A method for producing a coated color composition is disclosed.

The invention also provides a temperature sufficient to apply the above coating color composition to a paper or cardboard web and increase the viscosity by at least 2 times, in particular at least 5 times, even at least 10 times, ie at least 20 ° C., in particular at least 30 ° C., even more than 40 It relates to a coated paper or paperboard manufacturing method comprising the step of becoming above ℃. Thus, the coating is rapidly immobilized on paper or cardboard to prevent the flow of coating components.

The amount applied is not critical but is used in amounts of 1-50, in particular 3-25 g / m ² , calculated as the dry solids content for the area of paper or paperboard.

Coating can be performed on or off the machine. In either case, various coating methods can be used. For example, blade coating can be conveniently used in both cases, but air knife coating, roll coating, size press coating and cast coating are usually only used for on-machine coating. However, the main coating used is blade coating.

During the coating, the collar is initially applied to the paper surface in an excessive amount, for example by passing a paper web on the roll to a tray containing the coating collar by means of a roll applicator. Or a jet applicator may be applied. In the case of blade coating, an excessive amount of coating collar is removed from the paper by the scraping or wiping action of an ordinary metal blade that continues to compress the roll or cylinder surface. Several different blade coating devices have been developed but the blade coating principle is the same. The coating collars of the present invention can be used in all traditional coating processes on and off machine, with blade coating and size press coating, in particular blade coating.

After coating, the paper is dried. In the case of on-machines, the coating is usually carried out in the drying zone of the machine. Traditionally used drying means such as infrared radiation, heated cylinders or combinations thereof can be used in the drying zone. Drying means are not critical to the invention. When the paper is heated and dried by, for example, infrared radiation, it reaches a temperature which greatly increases the viscosity to passivate the coating color.

It has been found that the use of the specified polymer of the invention as a dispersant in pigment particles unexpectedly significantly improves gloss. Other properties are also improved. For example, a more uniform distribution of the color binder is achieved over the entire surface of the coated paper, which reduces staining. The color density obtained when the paper is printed is also increased. Enhancement of aggregation in the applied and dried coatings is also observed. Thus, when the paper of the present invention is folded, the cracking of the coating is reduced.

Many of the polymers of the present invention exhibit an increase in storage modulus (G ') of at least 100 times, in particular at least 1000 and even 10000 times when heated when adsorbed to the pigment particles (as opposed to when present in solution in the absence of such particles). Visible (when measured on a flow meter at low vibration shear). At this moment the water phase is basically released from the coating collar to create a gel-like structure.

Moreover, by using the designated polymer of the present invention, the coating can be instantaneously immobilized on the paper surface when heated. Thus, the coating system of the present invention is designed to be immobilized at the desired temperature and is designed for each paper machine.

In addition, staining due to the movement of binder and pigment from the coating to the base paper after coating and in the opposite direction during coating paper drying is greatly reduced with the use of the coating color of the present invention.

It is possible to produce coating color compositions with high solid material levels, which shortens the drying time after coating, thus accelerating the manufacturing process and thus reducing energy consumption. However, in the presence of high shear forces in combination with the high speed of the paper machine at these high solid material levels, improvement in the shear viscosity of the collar should be prevented.

It is possible to produce paper or cardboard having better properties than known methods. The invention therefore also relates to paper or cardboard produced by the above method.

Dispex, including traditional anionic sodium polyacrylates, is used as reference dispersant. More dispersants of the invention are needed to reach the same low viscosity when calculated on the basis of weight. The dispersant of the invention is more effective when calculated on the basis of charge. Coating is carried out in pilot scale coaters and laboratory coaters.

Example 1 (comparative)

Sodium polyacrylate dispersant 40% aqueous solution (Dispex N40, Ciba Specialty Chemicals) 3.38 g (0.9%), deionized water 86.32 g, defoamer 0.1 g (Coatosil 1378, Witco), tetrahedral precipitated calcium carbonate 150 g (Huber Engineered Materials) , SB latex 50% dispersion (Baystal P7105, Eka Polymer Latex) 33.33g (11%), CMC (Finnfix 10, Noviant) 10% aqueous solution of 8.40g (0.6%) was uniformly mixed to 60% by weight total solids Coating collars are made.

Example 2 (comparative)

40% aqueous solution of sodium polyacrylate dispersant (Dispex N40, Ciba Specialty Chemicals) 1.08 g (0.15%), 48.98 g deionized water, 0.1 g defoamer (Coatosil 1378, Witco), 72 g of rhombohedral precipitated calcium carbonate (Huber Engineered Materials), 16.06 g (11%) of SB latex 50% dispersion (Baystal P7105, Eka Polymer Latex) and 4.02 g (0.6%) of 10% aqueous solution of Finnfix 10, Noviant (CMC) are uniformly mixed to give a total solid content of 60% by weight. The collar is made.

Example 3

3.0 g (2%) of a 10% aqueous solution of styrene acryl butyl ester comb copolymer containing phosphonic acid and PEO / PPO comb as a dispersing agent with a molecular weight distribution of 5000-30000 g / mol as a dispersing agent, 62.68 g of deionized water, 0.1 g of antifoaming agent ( Coatosil 1378, Witco), trigonal precipitated calcium carbonate 150g (Huber Engineered Materials), SB latex 50% dispersion (Baystal P7105, Eka polymer Latex) 33.33g (11%), CMC (Finnfix 10, Noviant) 10% aqueous solution 8.48 g (0.6%) were mixed uniformly to produce a coating color of 60% by weight total solids.

Example 4

9.90 g (1.1%) of 17% aqueous solution of a polyurethane-based copolymer containing adhesive carboxylic acid, PEO segment and C ₁₆ alkyl group as a dispersant (US 4777224), 87.30 g of deionized water, 0.1 g of antifoaming agent (Coatosil 1378, Witco), rhombohedral precipitation A coating color having a total solid content of 60% by weight was prepared by uniformly mixing 150 g of calcium carbonate (Huber Engineered Materials) and 33.33 g (11%) of SB latex 50% dispersion (Baystal P7105, Eka polymer Latex).

Example 5

Polyurethane copolymer 20% colloidal dispersion (Jetsize AP15, Eka Chemicals) 2.74g (0.75%), deionized water 48.03g, defoamer 0.1g (Coatosil 1378, Witco), rhombohedral precipitated calcium carbonate 72g (Huber Engineered Materials), 16.06 g (11%) of SB Latex 50% dispersion (Baystal P7105, Eka polymer Latex) and 4.04 g (0.6%) of 10% aqueous solution of Finnfix 10, Noviant (CMC) are uniformly mixed to give a total solid content of 60% by weight. The collar is made.

Example 6 (comparative)

Sodium polyacrylate dispersant 10% aqueous solution (Dispex N40, Ciba Specialty Chemicals) 0.96 g (0.15%), polyurethane copolymer 20% colloidal dispersion (Jetsize AP15, Eka Chemicals) 2.43 g (0.75%), deionized water 50.78 g , 0.1 g antifoam (Coatosil 1378, Witco), rhombohedral precipitated calcium carbonate 64 g (Huber Engineered Materials), SB latex 50% dispersion (Baystal P7105, Eka Polymer Latex) 14.28 g (11%), CMC (Finnfix 10, Noviant) ) 3.60 g (0.6%) of 10% aqueous solution was uniformly mixed to prepare a coating color of 60% by weight total solids.

Example 7 (comparative)

Sodium polyacrylate dispersant 10% aqueous solution (Dispex N40, Ciba Specialty Chemicals) 0.56 g (0.3%), deionized water 43.46 g, defoamer 0.1 g (Coatosil 1378, Witco), kaolin clay (Speswhite, Imerys) 75 g, SB latex 50 16.67 g (11%) of% dispersion (Baystal P7105, Eka Polymer Latex) and 4.18 g (0.6%) of 10% aqueous solution of CMC (Finnfix 10, Noviant) were uniformly mixed to form a coating color with a total solid content of 60% by weight. do.

Example 8

The PCC color temperature dependent aspects of Example 3 and Comparative Example 1 were investigated using the flowmeter model UDS200 (PAAR Physica). Temperature tests are performed at 25-85 ° C. in the viscoelastic region.

Storage Examples at Various Temperatures of Comparative Examples 1 and 3 Coatings Coating of Comparative Example 1 Coating of Example 3 Temperature (℃) Storage modulus G '(Pa) Temperature (℃) Storage modulus G '(Pa) 25 155 25 11 35 47 35 13 45 47 45 22 55 64 55 171 65 68 65 2110 75 64 75 4820 85 81 85 9010

The aqueous 1 wt% polymer solution used as dispersant in Example 3 shows no visual precipitation during temperature increase to 20-95 ° C., so there is no clouding phenomenon.

Example 9

The PCC color of Example 3 and Comparative Example 1 was applied to paper according to the conditions of Table 2, and the physical properties of the coated paper were measured after drying.

Application condition apply Helicoater, 1000 rpm dry IR-heating and hot air Coating amount 14g / ㎡ Calendering Kleinenefers-calendar, 200 m / min, 80 ° C, 200 kN / m

Surface roughness (PPS-10) is measured according to SCAN-P21. Gloss is measured using a BYK-Gardner micro-gloss 75 ° meter. Color density is the average of yellow, cyan, magenta and black measured in ink-jet print using GretagMacbeth's GRETAG D19C Densitometer. Contact angle is measured after 10 seconds using Fibro DAT 1100. Deviation of latex from the surface is analyzed using a Shimadzu (Japan) chromatographer. Non-uniform ink absorption in the offset print is also measured. High values indicate nonuniform ink absorption. The results are shown in Table 3.

Properties of Coated Paper Unprocessed calendar Calendered Dispersant PPS-10 (㎛) Gloss unit (%) Color density Contact angle after 10 seconds (°) Standard Deviation in Latex Volume 1-8 mm Comparative Example 1 4.62 38.7 0.85 64 4853 5.09 Example 3 3.76 42.0 0.90 81 2875 4.66

Example 10

The PCC color temperature dependent aspects of Example 4 and Comparative Example 1 were investigated using the flowmeter model UDS200 (PAAR Physica). Temperature tests are performed at 25-85 ° C. in the viscoelastic region.

Comparative Examples 1 and 4 Storage Modulus at Various Temperatures of Coatings Comparative Example 1 Example 4 Temperature (℃) Storage modulus G '(Pa) Temperature (℃) Storage modulus G '(Pa) 25 155 25 81 35 47 35 246 45 47 45 1060 55 64 55 2740 65 68 65 6320 75 64 75 9700 85 81 85 15000

Example 11

The PCC color of Comparative Example 6, the PCC color of Example 5, and the PCC color of Traditional Comparative Example 2 containing the polymer of the present invention and a conventional dispersant combination are compared. Each color is applied to the paper using a draw-down coating applicator and the gloss of the coated paper is measured after drying and soft calendering.

Gloss is measured using a BYK-Gardner micro-gloss 75 ° meter. Color density is the average of yellow, cyan, magenta and black measured in ink-jet print using GretagMacbeth's GRETAG D19C Densitometer. Contact angle is measured after 10 seconds using Fibro DAT 1100.

Gloss of coated paper division Gloss of soft calendered paper Collar density Contact angle after 10 seconds Comparative Example 2 34 1.13 91 Example 5 39 1.14 95 Comparative Example 6 35 1.10 84

As can be seen from Table 5, in Comparative Example 6, even though the polymer of the present invention (polyurethane copolymer 20% colloidal dispersion (Jetsize AP15, Eka Chemicals)) was used, a coating having the required properties was not obtained. This is because the required action of the polymer used in the present invention is hampered by the presence of interfering species. This action is based on the combination of the polymer and pigment particles of the present invention and the required results are not achieved by the presence of traditional polyacrylate dispersants in the collar. Therefore, it is preferable to use only the polymer of the present invention as a dispersant in the coating color of the present invention.

Example 12

The PCC color (Example 3) and the traditional PCC color (Comparative Example 1) of the present invention are applied to a plastic film. The coating layer was separated from the film and mechanical properties were measured using Alwetron TH1 (Lorentzon & Wettre). Elongation and tensile energy absorption are measured.

Extensibility of the Coated Layer division Elongation (%) Tensile energy absorption Comparative Example 1 0.6 0.6 Example 3 2.9 1.8

Example 13

The PCC color (Example 3) and the traditional PCC color (Comparative Example 1) of the present invention are applied to paper as in Example 9. Fold the coated paper after drying and calendering. The coating of the present invention has reduced cracking compared to traditional coatings.

Example 14

Using a draw-down coating applicator Paper is coated and the gloss obtained with the PCC color of this invention (Example 3) is compared with the gloss of a traditional kaolin clay color (Comparative Example 7) using Dispex as a dispersant. PCC was replaced with clay to improve gloss. After light calendering, coated paper with PCC-containing color shows a higher gloss than coated paper with clay-containing color.

Gloss of coated paper division Gloss unit Example 3 44.3 Comparative Example 7 40.7

Example 15

Carboxymethyl group substitution degree of 0.95. 0.42 g (0.30) of hydrophobically modified carboxymethyl cellulose (HM-CMC) as disclosed in WO98 / 56825 having a C4 alkyl group substitution degree of 0.1, a C14 alkyl group substitution degree of 0.006, a molecular weight distribution of 20000-70000 g / mol, and an 86.3% solids content. %), 46.96 g of deionized water, 150 g of rhombohedral precipitated calcium carbonate (Huber Engineered Materials) with solid content of 80.5%, SB latex 50% dispersion (Baystal P7105, Eka polymer Latex) 26.83 g (11%), solids content 89.4% 1.13 g (0.75%) of CMC (Finnfix 10, Noviant) was uniformly mixed to produce a coating color with a total solids content of 60% by weight.

PCM color temperature dependent aspects containing HM-CMC are investigated using flowmeter model UDS200 (PAAR Physica). Temperature tests are performed at 25-85 ° C. in the viscoelastic region.

Storage modulus at various temperatures of coatings containing HM-CMC Temperature (℃) Storage modulus G '(Pa) 25 100 35 187 45 254 55 421 65 573 75 726 85 1180

The PCC color of the comparative example 2 is compared with the PCM color containing HM-CMC. Using a draw-down coating applicator A collar is applied to the paper and the gloss of the coated paper is measured after drying and soft calendering.

Gloss of coated paper division Soft Calender Finished Paper Gloss Comparative Example 2 34 Example containing HM-CMC 43

Higher gloss can be obtained using HM-CMC as a dispersant compared to the coating color of Comparative Example 2.

Claims (22)

A pigment particle aqueous slurry comprising an amphoteric polymer at least partially adsorbed on a pigment particle as a dispersant characterized by temperature-dependent viscosity properties in a manner in which the viscosity increases more than two times when the temperature is raised from 20 ° C. to 100 ° C. Or dispersion The slurry or dispersion according to claim 1, wherein the viscosity is increased by five times or more when the temperature is increased from 30 to 80 ° C. 3. Slurry or dispersion according to claim 1 or 2, characterized in that the solids content of the slurry or dispersion is at least 60% by weight. The slurry or dispersion according to any one of claims 1 to 3, wherein the Brookfield viscosity is 50-5000 mPa at less than 20 ° C. The slurry or dispersion according to any one of claims 1 to 4, wherein the pigment particles are weakly charged inorganic particles. Slurry or dispersion according to one of the preceding claims, characterized in that the pigment particles are selected from clay, titanium dioxide, calcium carbonate or mixtures thereof. The slurry or dispersion according to any one of claims 1 to 6, wherein the average molecular weight of the amphoteric polymer is 2000-200000. Slurry or dispersion according to claim 1, wherein the amphoteric polymer comprises a hydrophilic group selected from anionic moieties, PEO / PPO or mixtures thereof. The slurry or dispersion according to any one of claims 1 to 8, wherein the amphoteric polymer comprises at least partly charged hydrophilic groups. 10. Slurry or dispersion according to any one of claims 1 to 9, wherein the charged hydrophilic group is selected from sulfonates, phosphonates, carboxylates or mixtures thereof. 10. The slurry or dispersion as claimed in claim 1, wherein the amphoteric polymer comprises alternating hydrophobic and hydrophilic moieties along the backbone. 11. 12. The slurry or dispersion according to claim 11, wherein the hydrophilic attaching group is located along the backbone. 13. The slurry or dispersion according to claim 11 or 12, wherein the hydrophobic moiety is a C ₁ -C ₂₀ carbon chain. The slurry or dispersion according to any one of claims 1 to 13, wherein the amphoteric polymer is selected from acrylic ester copolymers having an accessory hydrophobic chain and a hydrophilic chain and having phosphonic acid or carboxylic acid as an anion. 14. The slurry or dispersion according to any one of claims 1 to 13, wherein the amphoteric polymer is selected from hydrophobically modified carboxymethyl cellulose. Slurry or dispersion according to claim 1, wherein the amphoteric polymer is selected from polyurethane copolymers having at least one carboxylic acid moiety as the anionic moiety. The slurry or dispersion according to claim 1, wherein the amphoteric polymer is selected from alpha olefin / maleic acid copolymers having at least one carboxylic acid moiety as the anionic moiety. Mixing at least partially adsorbed amphoteric polymers with pigment particles, water and pigment particles results in a slurry or dispersion exhibiting temperature dependent viscosity properties in a way that the viscosity increases more than two times as the temperature rises from 20 ° C. to 100 ° C. Process for preparing the slurry or dispersion of any one of claims 1 to 17 comprising the step of obtaining A slurry or dispersion of any one of claims 1 to 17 and an additive selected from a binder, a co-binder, a rheology modifier, a brightener, a pH adjuster, a foam inhibitor, a lubricant, a preservative, a dissolution inhibitor, and a temperature of 100 at 20 ° C. Coating color composition characterized by temperature-dependent viscosity properties in a manner that the viscosity increases more than two times when raised to ℃ A coating color comprising the steps of mixing the slurry or dispersion of any one of claims 1 to 17 with an additive selected from a binder, co-binder, rheology modifier, varnish, pH adjuster, foam inhibitor, lubricant, preservative, dissolution inhibitor. Composition preparation method 20. A method of making a coated paper or board comprising applying the coating color composition of claim 19 to a paper or board web and bringing it to a temperature sufficient to increase viscosity by more than two times. Paper or board made by the method of claim 21