FI118091B - New composition for coating paste - Google Patents

Description

118091 ΐ.ί'ί

New coating composition

The invention relates to the coating of paper and board, and relates in particular to a novel t pigment coating composition for coating paper and board. The new coating composition contains a pigment, a latex, optionally a polymer made of hydrophobic monomers in the presence of starch, optionally also other binders and, if necessary, known additives used in the coating compositions, and is characterized in that it contains styrene-maleimide. The invention also relates to paper or paperboard coated with a novel coating composition and all coating concepts.

The purpose of the coating is to improve the surface properties of the paper or board, such as gloss, printability and print quality. The most commonly used surface-to-surface treatment is pigment coating, whereby a coating or pigment-binder mixture is applied to the surface of the base material by means of 15 coating units or a separate coating machine, the coating layer is adjusted and finally the coating is dried. Conventional pigment coating compositions include pigment agents which may be one or more binders or binders, water and, optionally, additives such as curing agents, viscosity and water retention agents of the paste and j 4 - * i.

20 lubricants. The proportions of the components of the coating composition can vary quite a bit from 1 · 4 i '; the intended use and quality requirements of the final product, the coating method and · · · 4 · ·.

*. depending on the quality of the base paper.

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, ···. As coating pigments in pigment coating compositions are used e.g. kaolin; • 4 4 4 4 25 calcined kaolin, calcium carbonate, titanium dioxide, satin white, talc,. gypsum, chalk, aluminum hydroxide, barium sulphate and sodium aluminum silicate, of which · ***: the most commonly used are kaolin, calcined kaolin, talc and calcium carbonate.

4 4 4, ···. As binders, soluble binders such as starch, casein, • * * · · soy protein, carboxymethylcellulose and polyvinyl alcohol, or latexes may be used, such as styrene-butadiene (SB), acrylate and polyvinyl acetate 4, or. ·. starch-stabilized latex.

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Small amounts of various additives are added to the pigment coating compositions to improve the application properties or to give it certain specific properties. Such known additives include e.g. dispersants, flow modifiers · 5 agents, defoamers and defoamers, preservatives, lubricants, hardeners and optical brighteners.

U.S. Patent No. 2,577,624 uses a water soluble salt of styrene-maleic anhydride copolymer as a binder for the coating paste. WO-A-99/51815 discloses a kaolin pigment of a particular particle form suitable for coating compositions and styrene maleic anhydride as a possible hydrophilic additive. The summary of JP 62258732 mentions the use of styrene and a copolymer of maleic acid and / or maleic anhydride as a dispersant in aqueous solutions of calcium carbonate.

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According to the invention, it has now been found that the printability and print quality of the coated paper is substantially improved if the coating composition contains styrene-maleimide as an additional binder. Styrene-maleimide is an imitated 4 4 copolymer of styrene-maleic anhydride, which in turn is a copolymer of styrene with i-20 maleic anhydride. In the composition of the invention, a partially or completely imidated · 11 styrene maleic anhydride copolymer may be used.

• · ·· ** · • *. * · *. When mixed with a paper coating paste, styrene-maleimide significantly improves the surface energy of «· · 7¾ 25 paper by significantly reducing the polar component.

·; ··· Styrene maleimide is particularly well suited for coating systems using talc, kaolin and / or calcium carbonate as ΐ pigments. Styrene Maleimide ί * 'helps bind talc and kaolin particles more tightly than SB latex alone and can: • · * *: * ♦: also act as a dispersant. When does Styrene Maleimide Change Paper? 30 surface hydrophobic, the surface does not get wet and dries when printed * * *% * · ♦ - K; :: ···,; j • f.

118091-ΐ 3 easily with slight wetting of water with rapid evaporation. Styrene-maleimide can be used dispersed directly in the pigment or added to the paste as a binder.

Styrene-maleimide also improves paper surface strength and offset printability 5 when used as an additive binder with a calcium-containing pigment or dispersed directly in the pigment. For example, the particle structure of the precipitated calcium carbonate is crystalline, and therefore the surface of the paper coated with the paste containing the precipitated calcium carbonate may be coarse (large pores). The coating composition of the invention also provides a highly cohesive coating and a highly printable surface when using the 10 carbonate pigment. Thus, the invention relates to a novel coating composition comprising as components a) a pigment, b) latex, c) a polymer made from hydrophobic monomers, if necessary in the presence of starch, i.e. starch-stabilized latex and / or starch added if necessary; , and in addition e) styrene-malein: f.

imide.

• * ·. · 1! The coating paste composition according to the invention may contain from 0.1 to 5 parts, preferably from 0.1 to 3 parts, and more preferably from 0.5 to 2 parts, of styrene maleimide.

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In place of styrene maleimide, a partially imidated styrene maleic anhydride may also be used in the composition of the invention.

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25 When presenting the composition of coatings, the proportions of the components are generally calculated as *: · *: the total pigment amount being 100 and the other components · 1.

the proportions are given relative to the amount of total pigment. For all components' * .2. the proportions are given in dry parts. The coating composition of the invention? * »· ... ·; * ·: ··· The number of components in this presentation is as follows.

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Suitable pigments for the coating paste composition of the invention include coating pigments known in the art such as kaolin, calcined kaolin, gypsum, chalk, powdered precipitated calcium carbonate, titanium dioxide, satin white, talc, aluminum hydroxide, barium sulfate and sodium sulfate. Particularly suitable for the coating paste composition of the invention are calcium-containing pigments such as kaolin, calcined kaolin, gypsum and powdered or precipitated calcium carbonate, as well as talc, and mixtures thereof, in particular a mixture of talc and kaolin or carbonate and kaolin.

Suitable binders include latexes known in the art, such as styrene butadiene latexes

(SB), acrylate latexes and polyvinyl acetate latexes (PVAc), in particular SBdatexes. I

The coating composition of the invention may contain, in addition to latex also as starch stabilized latex and / or starch alone. In addition to these, other binders such as CMC may be used.

By starch-stabilized latex is meant a copolymer formed when polymerizing vinyl hydrophobic monomers in the presence of native or modified starch. Modified starch means, for example, chopped; . t (e.g., oxidized), anionized and / or canonized starch. As monomers • · f ··.

. *. * For example, hydrophobic ♦ · ♦ 'monomers such as styrene, alpha-methylstyrene, acrylates, acrylonitrile, etc. may be used in the preparation of 20 such copolymers | The preferred coating composition of the invention comprises a) 100 parts by weight of 25 pigments, b) 5 to 18 parts by weight of latex, c) 0 to 5 parts by weight of starch-stabilized latex, or · · · · · · · · · · · ··· starch alone, d) 0 to 3 parts of known additives, and e) 0.1 to 5 parts of styrene-maleimide. More preferably, the amount of latex is from 6 to 15 parts, further,. more preferably 8 to 14 parts, most preferably 9 to 12 parts. The amount of known additives is preferably 0.2 to 2.5 parts, more preferably 0.2 to 2.0 parts, for example about 1.5 parts.

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If it is desired to use a polymer made of hydrophobic monomers, i.e. starch-stabilized latex, in the presence of starch, it will be present in an amount of from 0.1 to 5 parts, more preferably from 0.2 to 4 parts, more preferably from 0.3 to 3 parts 1.5 parts.

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If starch alone is to be used in the composition of the invention, it is preferably in an amount of 0.5 to 5 parts, more preferably 1 to 3 parts, and most preferably 1.5 to 2.5 parts, for example about 2 parts.

When it is desired to use both 4 starch-stabilized latex and starch as an additive in the composition of the invention, their combined amount is preferably from 1 to 5 parts, more preferably from 2.5 to 4 parts.

A preferred coating paste composition according to the invention, also comprising as starch also starch alone, contains a) 100 parts of pigment, 70 parts of talc and 30 parts of kaolin, b) 10 parts of latex, c) 3 parts of starch, d) optionally known additives, and e) 3 parts styrene-maleimide.

. . Another preferred coating paste composition of the invention contains a) 100 parts * · * · ·, 1. * 20 pigments, of which 40 parts are talc and 60 parts kaolin, b) 10 parts latex, c) 3 • · * Λ; * · * .. * parts of starch, d) possibly known additives, and e) 3 parts of styrene-malein * * 5 • r ·. ' ... · imide.

♦ * e ··· «. · **. A particularly preferred calcium carbonate pigment-containing coating paste composition of the invention comprises a) 100 parts powdered calcium carbonate *: * ·: (GCC), b) 11 parts latex, c) 0.75 parts starch-stabilized latex and 2 parts *. **: starch alone, d) if necessary, known additives, and e) 0.75 parts styrene-maleimide.

• · · · «•«. Another preferred coating paste composition according to the invention comprises a) 100 parts • · * · *** · powdered calcium carbonate (GCC), b) 12 parts latex, c) 0.5 parts • * · ', -; > '! 118091 6 1 starch-stabilized latex, d) if necessary, known additives, and e) 1 part styrene-maleimide.

A preferred calcium carbonate pigment coating composition 5 according to the invention comprises a) 100 parts of doped calcium carbonate (PCC), b) 10 parts of latex, c) 2 parts of starch alone, d) if necessary, known additives and e) 2 parts of styrene-imine.

Another preferred coating paste composition according to the invention comprises a) 100 parts 10 powdered calcium carbonate (PCC), b) 9 parts latex, c) 3 parts starch alone and 1 part starch stabilized latex, d) if known; and e) 1 part styrene maleimide.

The coating composition of the ready-to-use coating paste composition of the invention will generally have a dry solids content of greater than 50%, for example 50-60%, preferably about 55% and up to about 62%, depending on the pigments used in the composition. ΐ

The invention also relates to paper or paperboard coated with the invention: J

. . as well as the use of styrene maleimide

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*. * 20 in coating compositions for coating paper or cardboard. M

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Thanks to the coating paste composition according to the invention, the surface strength, printability and thus the print quality of the paper or paperboard coated with the said paste are substantially improved, especially in the new rapid offset printing process.

The product of the invention improves the pore structure of the paper surface and *: **: provides hydrophobicity. Because the polar component is significantly reduced, the * · * \ tti surface of the paper is suitable for offset printing. The use of the t ** "; coating paste composition according to the invention is also advantageous from an environmental point of view, as · · · *: * ·: since offset printing can use faster drying colors and * 30 shorter drying times, thus achieving significant energy savings. need isopropanol, "· # · 7 118091 commonly used in offset printing in wetting water. Isopropanol is a slightly hazardous solvent and efforts have been made to reduce its use. '

The following examples illustrate the invention. Examples 1-6 illustrate various coating paste compositions of which Examples 2-6 are of the invention. In addition, all pastes of Examples 1-6 also contain common paste additives. Examples 6-7 show the experimental results obtained.

Example 1 (Reference Paste) 10 70 parts talc 30 parts kaolin 10 parts SB latex 3 parts starch 15

The base paste was prepared by mixing latex and cooked starch among the pigment slurry.

• · Example 2: v! 20 • 1 *: 1. 70 parts talc • · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · ·: · 1: 10 parts SB latex 3 parts starch 25 3 parts styrene maleimide ···· ... 1 Styrene maleimide was also slurried in the base paste. Otherwise, t - -rl was prepared as in Example 1. "'1 *« ·

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Example 3 40 parts talc> 60 parts kaolin 5 10 parts SB latex 3 parts starch; 3 parts styrene maleimide

The paste of the invention was prepared by first mixing a base paste as in Example 1. Styrene maleimide was slurried in the base paste.

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Example 4 100 parts powdered calcium carbonate 15 parts SB latex 2 parts starch g 0.75 parts starch stabilized latex \; 0.75 parts styrene maleimide *, *; The paste of the invention was prepared by mixing the pigment slurry with *: *: first, styrene maleimide and then the other ingredients.

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Example 5 *: 25,100 parts powdered calcium carbonate * · · * »· ♦♦ * 12 parts SB latex 1 · · · ** ... · * 0.5 parts starch-stabilized latex · '' * · 1 part styrene-maleimide The paste according to the invention was prepared by mixing with a pigment slurry; other substances. ί .k \; 4 9 118091

Example 6 100 parts precipitated calcium carbonate 5 parts 10 latex SB 2 parts starch 2 parts styrene maleimide

The paste of the invention was prepared by mixing pigment slurry with 4 styrene maleimide and then boiled starch. %

Example 7. Improvement of Printability with Talc Kaolin Pigment? The pastes of Examples 1 and 2, which are otherwise identical except that of Example 2 *, contain styrene-maleimide in accordance with the invention. In addition, both 'pastes contain common paste additives in the same way. 1 ··· • 4 •• a ·. ···: • ·: The base paper was coated with pastes with a pilot scale coater 10 g / m. 20 on each side of the paper. The papers were printed on a laboratory scale. The results of the paper analyzes are presented in Tables 1 and 2.

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Table 1. Improvement of Printability with Talc Kaolin Pigment 25 ________ NP Color- K&N IGT- Wet Rupture Wet pick Color Transfer ··· _ Absorption Vibration Ability (9.9 s)% Wet Rupture ( 15 s)> * · *% sorption% m / s (9.9 s)% to dry * · * · * ... * surface * '** · Ex. 1 20 1.5 0.65 3 41 48 * (comparison) • · .*···. MonT2 ΊΙ Ό ~ ÖM 18 62 ~ 53 • * • * Φ * · "l—« «» 1 1 .......... i m »

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From the results, it is found that, when using styrene-maleimide, the paper properties are clearly favorable for printing. The paste-coated paper of the invention is remarkably hydrophobic, as evidenced by the high wet-repellent value. In addition, 5 were able to use fast drying colors, which is economically advantageous.

Example 7. Improvement of Printability with Calcium Carbonate Pigment 10

Conventional SB latex was compared to a mixture in which part of the binder was replaced by styrene-maleimide, starch-stabilized latex and / or starch alone.

The pigment used was ground calcium carbonate (GCC) or precipitated calcium carbonate (PCC). In addition, standard additives were used in the pastes, which were the same for all test points. The paper was LWC base paper. The papers were printed on a laboratory-scale Briifbau machine.

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Table 2. 100 parts of ground calcium carbonate (GCC) as pigment

Reference Pasta A Pasta B Pasta C

Set off% ΤΪ2 ΤΪ3 ΤΪ5 ΤΪ3 Number of colors 1.16 1.15 1.22 1.23 to density 1.6 Color shift 94.3 94 95.6 96.5 Color rejection 6.7 7.2 5.7 2.8

Pilot Print, 57.5 63.6 58.3 60.7 Black Gloss%

Total surface energy 28.31 29.23 35.07 37.29 coated paper

Dispersive 27.82 29.01 35.05 36.92 Component, mN / m *

Polar 0.49 0.22 0.02 0.37 component, mN / m

Polymer 1.11 1.78 2 * swelling tendency

Ink tack, measured with Isit- 4.9 5 5.4 4.7

device, N

• · 7 * * _ * · Back trap-picking 0.5 0.68 0.53 0.55 • · * Offset test, Exercise 4 11.5 23.6 31.8 41.4 *** '. · * Times: ** · Wet Rejection 13.6 17 20.5 18.2 '♦ ** ·: 1.047 sec

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· '... · Reference Paste: 13 parts SB latex

Pasta A: 12 parts SB latex, 1 part starch-stabilized latex, 0.5 parts styrene-maleic * · * · *: 5 imides ··· 'J? J

Pasta B: 12 parts SB latex, 0.5 parts starch-stabilized latex, 1 part styrene-male · ***. imide * ♦ • · · •; * .j Pasta C: 11 parts SB latex, 2 parts starch, 0.75 parts starch-stabilized latex, Λ (0.75 parts styrene-maleimide • ** · .. 10 * * • * * * ·

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Table 3. 100 parts of precipitated calcium carbonate (PCC) as pigment

Reference Pasta A Pasta B Pasta C

Printed four-color gloss 73.4 76.8 73.7 78.3 *,

Total Surface Energy 34.94 32.56 36.79 25.69, Coated Paper

Dispersive 34.78 31.82 36.63 21.56 Component, mN / m

Polar 0.16 0.74 0.17 4.13 component, mN / m

Polymer 1.11 2.22 1.78 swellability

Ink tack, measured with Isit- 4.9 5.4 5.2

device, N

Back trap -picking 0.78 0.53 0.63 0.7

Offset test, Exercise 3 29.6 25.5 36.9 29.5 times ki _____: __: ____ Wet rejection 7.8 18 17.3 15.9 1.047 s j *. : Comparison: 13 parts SB-Iatex * *

Pasta A: 11 parts SB latex, 2 parts styrene maleimide • · ♦ • J *. 5 Pasta B; 10 parts SB latex, 2 parts starch, 2 parts styrene maleimide • *

Pasta C: 11 parts SB latex, 2 parts styrene maleic anhydride * * • · ί; • · «« · • · ···: • · ·

With both calcium carbonates, using the compositions of the invention, ·: ··· 10 dyed well on the surface, giving a clear print and better surface gloss.

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Claims (14)

1. Coating paste paste composition comprising as its components a) pigments, b) latex, c) optionally a polymer prepared from hydrophobic monomers in the presence of starch or starch-stabilized latex and / or starch alone, d) if necessary, additives used in coating compositions, characterized in that it further comprises e) styrene maleimine. Coating paste composition according to claim 1, characterized in that it comprises 0.1-5 parts, preferably 0.1-3 parts, and most preferably 0.5-2 parts styrene-maleimide. 10 The coating paste composition of claim 1, which contains as its components a) 100 parts of pigment, b) 5 to 18 parts of latex, c) 0 to 5 parts of starch stabilized latex or starch alone, d) 0 to 3 parts of known additives, characterized in that: it further comprises e) 0.1 - 5 parts styrene maleimide. The coating paste composition according to claim 1, which contains as its * * · • · components a) 100 parts pigment, b) 6 -15 parts latex, c) 0.2 - 4 parts starch «*: *: * · Stabilized latex or 1 - 3 parts of starch; * t * ·: so «·· The coating paste composition of claim 1, which contains as its components a) 100 parts of pigment, b) 9-12 parts of latex, c) 0.3 - 3 parts of starch - stabilized latex or 1.5 - 2.5 parts of starch, d) 0.2 - 2 parts of known additives, characterized in that it further comprises e) 0.5 - 2 parts of styrene-maleimide. 25 • · * ... 6. Coating paste composition according to claim 1, containing as its components a) 100 parts pigment, b) 6-15 parts latex, c) together 1-5 parts • · · starch stabilized latex and starch, d) additives known as needed, characterized in that it further comprises e) 0.1 - 3 parts styrene-maleimide. 16, i; 118091 1 'If The coating paste composition according to claim 1, which contains as its components a) 100 parts of a mixture of talc and kaolin, b) 10 parts of latex, c) 3 parts of starch, d) known additives, if necessary, characterized in that 5 further comprises e) 3 parts styrene maleimide. The coating paste composition of claim 1, which contains as its components a) 100 parts of finely divided calcium carbonate, b) 11 parts of latex, c) 0.75 parts of starch stabilized latex and 2 parts of starch alone, d) known additives, if necessary, characterized by it further comprises e) 0.75 parts of styrene maleimide. y Coating paste composition according to any one of claims 1-8, characterized in that styrene maleimide is fully or partially imitated styrene maleic anhydride. 15 Coating paste composition according to any one of claims 1-8, characterized in that the pigment is kaolin, gypsum, finely divided or precipitated calcium carbonate, or a mixture of some of these. • · «• · ·· · · · • · • ·; * · *; 2 0 11. The coating paste composition according to claim 10, characterized in that: *: the pigment is finely divided or precipitated calcium carbonate or a mixture of Taik * ϊ "ϊ and kaolin. ··· • 9 mm mm The coating paste composition according to any one of claims 1-8, characterized in that the latex is styrene butadiene latex. ♦ · • · ·· · · ♦ · ·· .. ·· * * 13. Paper or cardboard, characterized in that it is coated with a coating ··· • · * ··· * paste paste composition according to any of the claims 1 -8. · Use of styrene-maleimide in coating paste compositions intended. Γ ίδι coating of paper or cardboard.