JP2913839B2 - Coating composition for paper - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a paper coating composition, and more particularly to a paper coating composition capable of imparting excellent printability and printing effect to paper. What you want to do.

[0002]

2. Description of the Related Art Coated paper obtained by applying a coating composition mainly composed of a pigment and an aqueous binder to paper, and subjecting the coated paper to necessary steps such as drying and calendering is characterized by its excellent printing effect. Therefore, it is widely used in commercial prints, magazines and books, etc., but with the sophistication of quality requirements and the speeding up of printing, efforts to improve the quality of coated papers are still ongoing. Particularly in offset printing, which accounts for the majority of printing, improvement and improvement of ink receptivity under the influence of shampoo water, water resistance of wet topics and wet labs, and blister resistance in rotary printing are important issues in the industry. Has become.

Conventionally, to solve such problems, melamine-formaldehyde resin, urea-formaldehyde resin, or polyamide polyurea-formaldehyde resin, for example, Japanese Patent Publication No. 44-11667 and Japanese Patent Publication No. 59-32597.
There is known a method of adding a water-proofing agent, a printability improving agent, and the like as described in Japanese Patent Application Laid-Open Publication No. H11-163,028.

[0004] However, these conventional water-proofing agents and printability-improving agents all have effective properties, but on the other hand, serious disadvantages or inadequate effects are recognized in some of the properties, so that they are practically used. It was not always satisfactory.

[0005] For example, aminoplast resins such as melamine-formaldehyde resin and urea-formaldehyde resin not only generate a large amount of formaldehyde during work or from coated paper, but also have an effect of improving ink receptivity and blister resistance. Is hardly obtained, and when the pH of the coating composition is high, there is a problem that it is difficult to exert the water resistance effect.

[0006] Polyamide polyurea-formaldehyde resins are effective not only for improving water resistance but also for improving ink receptivity and blister resistance. However, their degree of improvement is in response to recent demands for higher coated paper quality. But it was not necessarily enough. Therefore, efforts have been made to further improve the quality. For example, Japanese Patent Application Laid-Open No. 62-125093 discloses a further improved paper coating composition. However, as the demands for the quality of coated paper have become higher thereafter, higher performance has been required.

[0007]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a paper having high water resistance and ink receptivity, and high paper blister resistance, which is difficult to obtain with the prior art. An object of the present invention is to provide a coating composition for use.

The present inventors have conducted intensive studies to solve such problems, and as a result, have found that a paper coating composition containing a specific water-soluble resin exhibits excellent performance. completed.

[0009]

That is, the present invention provides (I)
Pigment, (II) aqueous binder, and (III) condensation reaction product (a) of alkylene diamine or polyalkylene polyamine (a1) with urea (a2), and reaction of urea (b1) with glyoxal (b2) Disclosed is a paper coating composition containing a resin component containing a water-soluble resin (A) obtained by reacting a product (b). In the present invention, aldehydes (c), epihalohydrins (d), and α, γ-dihalo-β-hydrins are further added to the water-soluble resin (A) as the resin component (III).
The water-soluble resin (C) obtained by reacting the compound (B) selected from (e) can also be used. The resin component (III) according to the present invention comprises, in addition to the water-soluble resin (A) or the water-soluble resin (C), a polyalkylene polyamine (f) and / or a reaction product of a polyalkylene polyamine with a quaternizing agent.
(g) [Hereinafter, these polyalkylene polyamines (f) and / or reaction products (g) will be referred to as polyamines (D)]. The resin component (III) of the present invention further comprises a water-soluble resin (A) and a polyamine.
The product (E) obtained by reacting (D) or the product (F) obtained by further reacting a polyamine (D) with a water-soluble resin (C) may be used.

Hereinafter, the present invention will be described in more detail.

The water-soluble resin (A) used in the present invention
Examples of the alkylene diamine or polyalkylene polyamine (a1) serving as a raw material include, for example, ethylene diamine,
Aliphatic diamines such as propylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, iminobispropylamine, 3-azahexane-1,6-diamine, 4,7-diazadecane-
And polyalkylene polyamines such as 1,10-diamine. Among them, diethylenetriamine and triethylenetetramine are industrially advantageous. These alkylenediamines or polyalkylenepolyamines (a1) can be used alone or as a mixture of two or more.

Also, ureas as raw materials for the condensation reaction product (a)
Examples of the urea (b1) serving as a raw material for (a2) and the reactant (b) include urea, thiourea, guanylurea, methylurea, and dimethylurea. These can be used alone or in combination of two or more. The ureas (a2) as the raw material of the condensation reactant (a) and the ureas (b1) as the raw material of the reactant (b) may be the same or different. From an industrial point of view, urea is preferably used.

The water-soluble resin (A) of the present invention comprises a condensation reaction product (a) of an alkylenediamine or polyalkylene polyamine (a1) with a urea (a2), and a urea (b1) and a glyoxal (b2). By reacting the reaction product (b).

The condensation reaction of the alkylene diamine or polyalkylene polyamine (a1) with the ureas (a2) is usually carried out in 10
At a temperature of about 0 to 180 ° C, preferably about 110 to 160 ° C, while removing generated ammonia to the outside of the system, 1
Approximately 6 hours. The amount of the urea (a2) to be used is preferably 0.5 to 1 mol based on 1 mol of the primary and secondary amino groups of the alkylenediamine or polyalkylenepolyamine (a1). At this time, a part of the urea (a2) was converted to an alkylenediamine or a polyalkylenepolyamine (a1) by 120.
To 180 ° C., preferably 140 to 160 ° C. to carry out primary deammonification, and then the remaining urea (a2) is added, and further 100 to 180 ° C., preferably 110 to 1 ° C.
The reaction can also be carried out in two stages, such as at 60 ° C. for secondary deammonification.

One reactant (b) is obtained by mixing a urea (b1) and a glyoxal (b2) in the presence of water, as is usually done. At this time, glyoxal
The amount of (b2) used is preferably about 0.5 to 5 mol per 1 mol of urea (b1). The reactant (b) may be reacted with formaldehyde before or after reacting the urea (b1) with the glyoxal (b2) to form a methylol compound. Further, the methylolated product can be further converted to an alkyl etherified product or a polyoxyalkylene etherated product. Furthermore, before or after reacting ureas (b1) and glyoxal (b2), those polymerized after reacting with a monomer having an amide group such as acrylamide or methacrylamide, or ureas (b1)
And glyoxal (b2), followed by further reacting a polymer having an amide group such as polyacrylamide or polymethacrylamide.

The condensation reaction product (a) and the reaction product (b) thus obtained are further reacted to obtain a water-soluble resin (A). The reaction is preferably carried out when the total concentration of condensation reactant (a) and reactant (b) is about 20-80% by weight.
And more preferably in an aqueous solution of about 30 to 70% by weight. Preferably, the pH is adjusted to 7 or less, more preferably to pH 1 to 5 with an acid, for example, hydrochloric acid, sulfuric acid, phosphoric acid, formic acid, acetic acid, and the like.
The reaction is carried out for 10 hours. After completion of the reaction, if necessary, the pH is adjusted to 6 to 10 using caustic soda or caustic potash to obtain the water-soluble resin (A) used in the present invention. The water-soluble resin (A) is obtained in the form of an aqueous solution.
It is 1000 cps and the pH is 6-10.

In the present invention, the water-soluble resin (A) can be used as it is as the resin component (III), but the water-soluble resin (A) may further contain an aldehyde (c) and an epihalohydrin (d). And a water-soluble resin (C) obtained by reacting at least one compound (B) selected from α, γ-dihalo-β-hydrins (e) can be used as the resin component (III).

The raw material of the water-soluble resin (C)
Among the compounds (B) to be reacted with (A), the aldehydes (c) include, for example, alkyl aldehydes such as formaldehyde, acetaldehyde and propyl aldehyde, and alkyl dialdehydes such as glyoxal, propane dial and butane dial. Etc. can be used. Industrially, formaldehyde and glyoxal are preferred. Each of these aldehydes can be used alone or as a mixture of two or more.

The epihalohydrins (d) have the general formula

[0020]

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[Wherein, X represents a halogen atom, w represents 1, 2 or 3]. Preferred examples include epichlorohydrin, epibromohydrin and the like. These epihalohydrins may be used alone or as a mixture of two or more.

The α, γ-dihalo-β-hydrins (e) have the general formula

[0023]

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Wherein X and Z each represent a halogen atom, and Y represents a hydroxyl group.
3-dichloro-2-propanol and the like.

When reacting the water-soluble resin (A) with the aldehydes (c), the pH is preferably 7 or less, more preferably 3 to 6 with an acid such as hydrochloric acid, sulfuric acid, phosphoric acid, formic acid or acetic acid. After adjusting the temperature to
The reaction is performed for about 10 hours. Further, it is also preferable to first react under alkaline conditions of pH 8 to 12, and then adjust the pH to 7 or less, more preferably to an acidity of pH 3 to 6, and continue the reaction. In the latter case, the reaction under alkalinity is
This is performed at about 40 to 80 ° C. for about 1 to 10 hours. The amount of the aldehyde (c) used is based on 1 mole of the water-soluble resin (A).
It is preferable that the aldehyde group is about 0.1 to 3 mol. After the above reaction, if necessary, the pH is adjusted to 6 to 10 using caustic soda, caustic potash, or the like, whereby an aqueous solution of the water-soluble resin (C) used in the present invention is obtained.

Water-soluble resin (A) and epihalohydrins (d)
Alternatively, when reacting with an α, γ-dihalo-β-hydrin (e), the pH is preferably 5 or more, more preferably the pH is 5 or more.
The reaction is carried out at a temperature of about 30 to 90 ° C., preferably about 40 to 80 ° C. for about 1 to 10 hours under the conditions of 6 to 9. The amount of the epihalohydrins (d) or α, γ-dihalo-β-hydrins (e) used is based on 1 mol of the water-soluble resin (A).
About 0.1 to 3 mol is preferable.

The aldehydes (c), epihalohydrins (d) and α, γ-dihalo-β-hydrins (e) used to obtain the water-soluble resin (C) can be used alone or in combination with each other.
A combination of more than one species may be used. For example, aldehydes (c) and epihalohydrins (d) can be used simultaneously, and aldehydes (c) and α, γ-dihalo-β-hydrins (e) can be used simultaneously.

The water-soluble resin (C) is obtained in the form of an aqueous solution,
Preferably, the viscosity of the 60% by weight aqueous solution at 25 ° C. is 1
It is 00-1000 cps and the pH is 6-10.

The paper coating composition of the present invention comprises a pigment (I), an aqueous binder (II), and the water-soluble resin (A) described above.
Or a resin component (III) containing a water-soluble resin (C), wherein the resin component (III) is a water-soluble resin (A)
Alternatively, the water-soluble resin (C) may be used alone or may contain other components, or may be obtained by further reacting the water-soluble resin (A) or the water-soluble resin (C) with other components. Good. For example, in addition to the water-soluble resin (A) or the water-soluble resin (C), a polyalkylene polyamine (f) and / or
Alternatively, it is also effective to contain a reaction product (g) of a polyalkylene polyamine with a quaternizing agent (referred to as polyamine (D) as described above). Further, the water-soluble resin (A)
And a product obtained by further reacting with a polyamine (D).
(E) or the product (F) obtained by further reacting the water-soluble resin (C) with a polyamine (D) to obtain a resin component (I)
It is also effective to use as II).

Here, the polyamine (D) itself or a polyalkylene polyamine as a raw material for the reaction is a compound having two primary amino groups and at least one secondary amino group in the molecule. Include, for example, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, iminobispropylamine, 3-azahexane-1,6-diamine, 4,7-diazadecane-
1,10-diamine and the like can be mentioned.

The quaternizing agent which is reacted with the polyalkylene polyamine to obtain the reaction product (g) includes:
The following various types can be used.

[0032] In formula R ¹ -X [wherein, R ¹ is a lower alkyl group (e.g., having about 1 to 6 carbon atoms), lower alkenyl groups (e.g., having about 2 to 6 carbon atoms),
Represents a benzyl group or a phenoxyethyl group, and X represents a halogen atom]. Preferred examples include, for example, methyl chloride, ethyl chloride, propyl chloride, allyl chloride, benzyl chloride, phenoxyethyl chloride, and bromides and iodides corresponding to these chlorides.

A dialkyl sulfite represented by the general formula (R ² O) ₂ SO _v [wherein R ² represents a lower alkyl group (for example, having about 1 to 6 carbon atoms) and v represents 1 or 2] Dialkyl sulfate. Preferred examples include dimethyl sulfate, diethyl sulfate, dimethyl sulfate, diethyl sulfate and the like.

General formula

[0035]

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Wherein R ³ represents a hydrogen atom, a lower alkyl group (for example, about 1 to 6 carbon atoms), a hydroxy lower alkyl group (for example, about 1 to 6 carbon atoms) or a phenyl group; Derivatives. Preferred examples include ethylene oxide, propylene oxide, butylene oxide, styrene oxide, glycidol and the like.

General formula

[0038]

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Wherein X represents a halogen atom and w represents 1, 2 or 3; and an epihalohydrin represented by the formula:
Preferred examples include epichlorohydrin, epibromohydrin and the like.

General formula HOCH ₂ (CH ₂ ) _w X wherein X represents a halogen atom, w is 1, 2 or 3
A monohalohydrin represented by the formula: Preferred examples include ethylene chlorohydrin, ethylene bromohydrin and the like.

General formula

[0042]

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Wherein X represents a halogen atom, one of Y and Z represents a halogen atom, and the other represents a hydroxyl group. Preferred examples are 1,3-
Dichloro-2-propanol, 2,3-dichloro-1-
And propanol.

Among these quaternizing agents, epichlorohydrin is particularly preferred. The compounds to be quaternizing agents as described above can be used alone or in combination of two or more.

As the polyamine (D), only the polyalkylene polyamine (f) may be used, or only the reaction product (g) of the polyalkylene polyamine and the quaternizing agent may be used. The alkylene polyamine (f) and the reaction product (g) may be used simultaneously.

Examples of the pigment (I) in the present invention include white inorganic pigments such as kaolin, talc, calcium carbonate (heavy or light), aluminum hydroxide, satin white, titanium oxide, and polystyrene, melamine-formaldehyde resin. And white organic synthetic pigments such as urea-formaldehyde resin. These can be used alone or in combination of two or more. Still further, a colored inorganic or organic pigment may be used in combination.

Examples of the aqueous binder (II) in the present invention include water-soluble binders such as oxidized starch, phosphorylated ester, polyvinyl alcohol, casein, gelatin, carboxymethyl cellulose, styrene-butadiene resin, and vinyl acetate resin. And water-emulsifying binders such as ethylene-vinyl acetate resin and methyl methacrylate resin. These can be used alone or in combination of two or more.

The preferred composition ratio in the paper coating composition of the present invention is 5 to 200 parts by weight, more preferably 10 to 5 parts by weight of the aqueous binder (II) per 100 parts by weight of the pigment (I).
0 parts by weight, 0.05 to 5 parts by weight, more preferably 0.1 to 2 parts by weight of the resin component (III). The resin component (III) mentioned here
When the water-soluble resin (A) or the water-soluble resin (C) is used alone, the water-soluble resin (A) or the water-soluble resin (C) and the polyamine (D) are used. When a product (E) obtained by further reacting a polyamine (D) with (A) is used, and a polyamine is further added to the water-soluble resin (C).
This applies to the case where the product (F) obtained by reacting (D) is used.

The resin component (III) used in the present invention is generally added and mixed at the time of preparing a paper coating composition. The effects of the present invention can be achieved even when the embodiment of mixing with the components is adopted.

In the paper coating composition of the present invention, other components such as a dispersant, a viscosity / fluidity regulator, an antifoaming agent, a preservative, a lubricant, a water retention agent, a dye / colored pigment, etc. And the like can be added as necessary.

The paper coating composition of the present invention can be prepared by a conventionally known method such as a blade coater, an air knife coater, a bar coater, a size press coater, a gate roll coater, and a cast coater. Coated on paper substrate. Thereafter, necessary drying is performed, and if necessary, a smoothing treatment is performed with a super calender or the like, whereby a coated paper can be manufactured.

The term “paper” used in the present specification has a broad meaning, and includes paper and paperboard in a narrow sense.

[0053]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to Reference Examples and Examples. The percentages in the text are based on weight unless otherwise specified. The viscosity is a value at 25 ° C.

Reference Example 1 A four-necked flask equipped with a thermometer, a reflux condenser and a stirring rod was charged with 146.2 g (1.0 mol) of triethylenetetramine and 180.2 g (3.0 mol) of urea, and the internal temperature was 120 to 140 ° C.
For 2 hours to carry out a deammonification reaction. Thereafter, 156.1 g of water was added to obtain a resin aqueous solution. Further, a resin solution previously prepared from 12.0 g (0.2 mol) of urea and 72.5 g (0.5 mol) of a 40% aqueous glyoxal solution was added,
The pH of the system was adjusted to 4.0 with 70% sulfuric acid and reacted at 70 ° C. for 4 hours. Then, adjust the pH to 7.0 with aqueous sodium hydroxide solution.
To obtain an aqueous solution of a water-soluble resin having a concentration of 60% and a viscosity of 75 cps.

Reference Example 2 An aqueous solution of a water-soluble resin obtained in the same manner as in Reference Example 1.
9.0g, 37% formalin 40.6g (0.5mol)
And adjust the pH of the system to 4.0 with 70% sulfuric acid.
For 4 hours. Then, p with aqueous sodium hydroxide solution
H was adjusted to 7.0 to obtain an aqueous solution of a water-soluble resin having a concentration of 60% and a viscosity of 300 cps.

Reference Example 3 An aqueous solution of a water-soluble resin obtained in the same manner as in Reference Example 1.
9.0 g, and epichlorohydrin 46.3 g (0.5 mol)
And 30.9 g of water, adjusted to pH 8.0 with aqueous sodium hydroxide solution, and reacted at 70 ° C. for 4 hours to obtain an aqueous solution of a water-soluble resin having a concentration of 60%, a viscosity of 290 cps and a pH of 6.6.

Reference Example 4 An aqueous solution of a water-soluble resin obtained in the same manner as in Reference Example 1.
9.0 g, and 14.6 g (0.1
Mol) and 9.1 g of water, with a concentration of 60%, a viscosity of 340 cps,
An aqueous solution of a water-soluble resin having a pH of 8.0 was obtained.

Reference Example 5 The same apparatus as used in Reference Example 1 was charged with 43.9 g (0.3 mol) of triethylenetetramine and 140.3 g of water.
While keeping the temperature at 0 ° C or lower, further epichlorohydrin 166.6
g (1.8 mol) were added dropwise. Thereafter, 499.0 g of an aqueous resin solution obtained in the same manner as in Reference Example 1 was added, and reacted at 50 ° C. for 1 hour to obtain a concentration of 60%, a viscosity of 300 cps, and a pH of 6.5.
To obtain an aqueous solution of a water-soluble resin.

Comparative Reference Example 1 A four-necked flask equipped with a thermometer, a reflux condenser, and a stirring rod was charged with 146.2 g (1.0 mol) of triethylenetetramine and 30.0 g (0.5 mol) of urea. ° C
For 3.5 hours to carry out a deammonification reaction. Then, 73.1 g (0.5 mol) of adipic acid was charged and the internal temperature was reduced to 15
The deamidation reaction was performed for 5 hours while maintaining the temperature at 0 to 160 ° C. Then, the internal temperature was lowered to 130 ° C, 120.1 g (2.0 mol) of urea was charged, and a deammonification reaction was performed at 120 to 130 ° C for 2 hours. Thereafter, 284.5 g of water was added to obtain a resin aqueous solution. Further, 60.9 g (0.75 mol) of 37% formalin was charged, the pH of the system was adjusted to 4 to 5 with 70% sulfuric acid, and the reaction was carried out at an internal temperature of 70 ° C for 4 hours. Thereafter, the pH was adjusted to 6.5 with an aqueous solution of caustic soda to obtain an aqueous resin solution having a concentration of 50% and a viscosity of 140 cps.

Examples Using the aqueous solutions of the water-soluble resins obtained in Reference Examples 1 to 5 and Comparative Reference Example 1, coating compositions for paper having the formulations shown in Table 1 were prepared.

[0061] Note) Ultra White 90: Clay Carbital 90 manufactured by Engel Hard Minerals Co., Ltd. USA: Calcium carbonate Sumireze Resin manufactured by Fuji Kaolin Co., Ltd. DS-10: Polyacrylic acid pigment dispersant SN-307 manufactured by Sumitomo Chemical Co., Ltd. Styrene butadiene-based latex manufactured by Sumitomo Nogatack Co., Ltd. Oji Ace A: Oxidized starch manufactured by Oji National Co., Ltd. Parts by weight indicate solid content weight.

The prepared paper coating composition had a total solid content of 6%.
After adjusting each with water and a 10% aqueous solution of caustic soda so that the pH becomes 0% and the pH is about 9.0, the coating amount is applied to one or both sides of high-quality paper having a basis weight of 80 g / m ² using a wire rod. Was applied to be 14 g / m ² . Immediately after the application, dry with hot air at 120 ° C. for 30 seconds.
The resultant was conditioned at 0 ° C. and a relative humidity of 65% for 16 hours, and further subjected to a supercalender treatment twice at a temperature of 60 ° C. and a linear pressure of 60 kg / cm to obtain a coated paper.

The coated paper thus obtained was subjected to tests for water resistance, ink acceptability and blister resistance. The test results are shown in Table 2. The test method is as follows.

Water resistance (a) Wet rub method Ion-exchanged water (approximately 0.1 ml) was dripped onto the coated surface, rubbed 7 times with a fingertip, and the eluted amount was transferred to black paper, and the elution amount was visually determined. . The judgment criteria were as follows. Water resistance (poor) 1-5 (excellent) (b) Wet topic method Using an RI tester (Meiji Seisakusho), wet the coated surface with a water supply roll, print, and observe the peeling state with the naked eye. Judged. The judgment criteria were as follows. Water resistance (poor) 1-5 (excellent)

Ink Acceptability (A) Method A Using a RI tester, the coated surface was wetted with a water supply roll and then printed, and the ink acceptability was visually observed and judged. The judgment criteria were as follows. Ink acceptability (poor) 1 to 5 (excellent) (b) Method B Using an RI tester, printing was performed while water was mixed into the ink, and the ink acceptability was visually observed and judged. The judgment criteria were as follows. Ink acceptability (poor) 1-5 (excellent)

Using a blister-resistant RI tester, double-sided printing was performed on a double-side coated paper using an offset rotary printing ink. Was determined. The judgment criteria were as follows. Blister resistance (poor) 1-5 (excellent)

[0067] Note) ^{* 1} pH at 25 ° C ^{* 2} Viscosity at 25 ° C ^{* 3} Wet lab method ^{* 4} Wet topic method

[0068]

The coated paper obtained by using the paper coating composition of the present invention is excellent in ink acceptability and water resistance, and particularly excellent in blister resistance, and furthermore, almost no formaldehyde odor is generated. It has various excellent and effective properties, such as no or none.

Continuation of the front page (58) Field surveyed (Int. Cl. ⁶ , DB name) D21H 19/62 C09D 161/24 C09D 163/00 C09D 179/02

Claims (6)

(57) [Claims] 1. A urea (b) is added to (I) a pigment, (II) an aqueous binder, and (III) a condensation reaction product (a) of an alkylenediamine or a polyalkylene polyamine (a1) with a urea (a2).
A paper coating composition comprising a resin component containing a water-soluble resin (A) obtained by reacting a reactant (b) of 1) with glyoxal (b2). 2. The resin component (III) is selected from the group consisting of the water-soluble resin (A) and aldehydes (c), epihalohydrins (d), and α, γ-dihalo-β-hydrins (e). The coating composition for paper according to claim 1, which is a water-soluble resin (C) obtained by reacting the compound (B). 3. The resin component (III) further comprises a polyamine (D) selected from a polyalkylene polyamine (f) and a reaction product (g) of the polyalkylene polyamine with a quaternizing agent. Paper coating composition. 4. The resin component (III) further comprises a polyamine (D) selected from a polyalkylene polyamine (f) and a reaction product (g) of the polyalkylene polyamine with a quaternizing agent. Paper coating composition. 5. The resin component (III) further comprises a water-soluble resin (A) and a polyamine (D) selected from a polyalkylene polyamine (f) and a reaction product (g) of a polyalkylene polyamine with a quaternizing agent. The paper coating composition according to claim 1, which is a product (E) obtained by reacting 6. The resin component (III) further comprises a water-soluble resin (C) and a polyamine (D) selected from a polyalkylene polyamine (f) and a reaction product (g) of a polyalkylene polyamine with a quaternizing agent. 3. The paper coating composition according to claim 2, which is a product (F) obtained by reacting