JPH0672399B2 - Coating composition for paper - Google Patents

Description

TECHNICAL FIELD The present invention relates to a paper coating composition that provides a coated paper having excellent printability and printing effect.

<Prior Art> A coated paper obtained by applying a coating composition for paper mainly composed of a pigment and an aqueous binder to paper and performing necessary steps such as drying and calendering has an excellent printing effect. It is widely used for commercial prints, magazines, books, etc. due to its features, but efforts are being made to improve the quality of coated paper as demand for quality becomes higher and printing speed increases. Especially in offset printing, which occupies most of printing, ink acceptability under the influence of squeezing water, water resistance of wet topics and wet rubs, improvement of blister resistance in rotary printing,
Improvement is an important issue for the industry.

Conventionally, melamine-formaldehyde resin, urea-formaldehyde resin or polyamide polyurea-formaldehyde resin such as Japanese Patent Publication No.
There is known a method of trying to solve the problem by adding a water-proofing agent and the like shown in No. -11667 and Japanese Patent Publication No. 59-32597.

<Problems to be Solved by the Invention> However, all of the conventionally used water-proofing agents and the like have effective properties, but on the other hand, they have serious drawbacks and are not satisfactory in practice.

For example, aminoplast resins such as melamine-formaldehyde resin and urea-formaldehyde resin not only generate a large amount of formaldehyde at the time of work and coated paper, but also hardly obtain the effect of improving ink acceptability and blister resistance. Also, the water resistance effect becomes extremely difficult to obtain as the pH of the coating composition increases. Furthermore, the polyamide polyurea-formaldehyde resin is effective in improving not only water resistance but also ink acceptability and blister resistance, but the degree of improvement is still unsatisfactory with the recent demand for higher quality coated paper. It is sufficient and there is a demand for higher performance. The object of the present invention is to meet such requirements, by using a coating composition for paper containing a specific resin, imparts to the coated paper a high degree of water resistance, ink acceptability and the like, which cannot be obtained by conventional techniques. Especially.

<Means for Solving the Problem> The inventors of the present invention have earnestly studied to obtain a paper coating composition that imparts high water resistance, ink acceptability, and the like to coated paper.
(I) Pigment, (II) Aqueous binder and (III) (a) Polyalkylene polyamine (b) Obtained by reaction of alicyclic dibasic carboxylic acid and / or alicyclic dibasic carboxylic acid with glycols A reaction product having a free carboxyl group to be used (c) A coating composition for paper containing a water-soluble thermosetting resin reacted with ureas and (d) formaldehyde is used for improving the intended performance of coated paper. The inventors have found that it is extremely effective and completed the present invention. The present invention is characterized by using the above-mentioned water-soluble thermosetting resin (III), and further, the alicyclic dibasic carboxylic acid of the reaction component (b) forming the (III) and The use of a reaction product having a free carboxyl group obtained by the reaction of an alicyclic dibasic carboxylic acid and / or a glycol is characterized.

Further details will be given in the context of the present invention.

Water-soluble thermosetting resin used in the present invention (III)
The (a) polyalkylene polyamine used for the production of is a compound having two primary amino groups and at least one secondary amino group in the molecule, and specific examples thereof include diethylenetriamine, triethylenetetramine, and tetraethylene. Pentamine, iminobispropylamine,
Examples thereof include 3-azahexane-1,6-diamine and 4,7-diazadecane-1,10 diamine. These polyalkylene amines can be used not only as one kind but also as a mixture of two or more kinds. Further, it does not hinder the combined use of the aliphatic diamine such as ethylenediamine and propylenediamine with the above-mentioned polyalkylenepolyamine within a range not impairing the object of the present invention.

Next, (b) an alicyclic dibasic carboxylic acid is a generic term that includes compounds having two carboxyl groups in the molecule, their esters, and their acid anhydrides. Representative examples of such alicyclic dibasic carboxylic acid are as follows.

Carboxylic acids such as tetrahydrophthalic acid, hexahydrofuric acid, cyclohexane-1,4-dicarboxylic acid, 4-methyltetrahydrophthalic acid and their esters, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, 4 -Methyl tetrahydrophthalic anhydride,
Acid anhydrides such as 4-methylhexahydrophthalic anhydride, Δ ⁴ -tetrahydrophthalic anhydride, and 4-methyl-Δ ⁴ -tetrahydrophthalic anhydride.

These may be only one kind or a combination of two or more kinds,
Further, together with these dibasic carboxylic acids, other dibasic carboxylic acids, such as aliphatic dicarboxylic acids such as adipic acid and glutaric acid, or aromatic dicarboxylic acids such as terephthalic acid and phthalic acid, to the extent that the effects of the present invention are not impaired. An acid may be used in combination.

Examples of glycols include alkylene glycols such as ethylene glycol, propylene glycol and butanediol, cycloalkylene glycols such as cyclopentanediol and cyclohexanediol, alkenylene glycols such as butenediol and octenediol, diethylene glycol and dipropylene glycol. ,
Polyalkylene glycols such as triethylene glycol, polyethylene glycol, polytetramethylene glycol, ethylene oxide adduct of bisphenol A,
Examples thereof include ethylene oxide adducts of hydrogenated bisphenol A.

Furthermore, as the reaction product having a free carboxyl group obtained by the reaction of an alicyclic dibasic carboxylic acid and glycols, the alicyclic dibasic carboxylic acid and the glycols can be used as a carboxylic acid excess mole. It is a polyester having a carboxyl group at the molecular end obtained by reacting in a ratio. The reaction between the alicyclic dibasic carboxylic acid and glycols is usually carried out at 80 to 200 ° C. for 30 hours in the presence or absence of a catalyst.
It is carried out by heating for minutes to 2 hours.

The (c) ureas may include urea, thiourea, guanylurea, methylurea, dimethylurea, etc., but urea is preferable from the industrial viewpoint.

Next, the reaction method of each component (a), (b), (c) and (d) will be described. The resin of the present invention includes, for example, the component (a),
It can be produced by reacting (d) with the reaction products of (b) and (c). This component (a),
The reactions of (b) and (c) can be carried out in any order.

First of all, the components (a) and (b) can be reacted and then the component (c) can be reacted. Components (a) and (b)
At a temperature of 120 to 250 ° C, preferably 130 to 200 ° C,
It is carried out in 2 to 12 hours while removing the produced water out of the system. The carboxyl group in the component (b) is reacted in a ratio of 0.4 to 4 equivalents, preferably 0.8 to 3 equivalents, relative to 1 mol of the polyalkylene polyamine of the component (a). The reaction between the dehydration condensation reaction product thus obtained and the urea of the component (c) is carried out at a temperature of 100 to 180 ° C, preferably 110 to 160 ° C.
Then, it is carried out for 1 to 6 hours while removing the generated ammonia out of the system. The amount of the component (c) used is 1 with respect to 1 equivalent of the amino group in the component (a), that is, the primary and secondary amino groups.
It is an equivalent or less, preferably 0.1 to 0.8 equivalent.

Alternatively, first react components (a) and (c),
Then, the component (b) can be reacted, and further the component (c) can be reacted. Component (c) is used in an amount of 0.2 to 1 mol, preferably 0.3 to 0.8 mol, per 1 mol of component (a), at a temperature of 100 to 180 ° C., preferably 110 to 160 ° C.
Deammonification reaction is carried out for an hour. The reaction of the reaction product thus obtained with the component (b) is carried out at a temperature of 120 to 250 ° C.
It is preferably carried out at 130 to 200 ° C. for 2 to 12 hours while removing generated water out of the system. The component (b) is the component (a)
It is used in the range of 0.2 to 2 equivalents, preferably 0.3 to 1.8 equivalents, per mol. The step of reacting the reaction products of the components (a), (b) and (c) thus obtained with the component (c) again is carried out at a temperature of 100 to 180 ° C, preferably 110 to 160 ° C. It is performed for 1 to 6 hours. The amount of the component (c) used is 2 with respect to 1 equivalent of the secondary amino group in the component (a).
The amount is not more than the equivalent, preferably in the range of 0.1 to 1.5 equivalents.

As another method, the components (a), (b) and (c) are simultaneously reacted, and the resulting reaction product is further supplemented with the component (c).
Can also be reacted. First component (a), (b)
The reaction of (c) is carried out at a temperature of 100 to 200 ° C., preferably 110
It is carried out at ˜180 ° C. for 2 to 12 hours while removing generated ammonia and water out of the system. The proportion of each component used in this step is 0.2 to 2 equivalents, preferably 0.3 to 1.8 equivalents of the carboxyl group of component (b), 0.2 to 1 mol of component (c), and preferably 1 to 1 mol of component (a). 0.3 to 0.8 mol is suitable. The step of further reacting the component (c) with the reaction product thus obtained is carried out at a temperature of 100 to 180 ° C., preferably 110 to 160 ° C. for 1 to 6 hours. The amount of the component (c) used is 2 equivalents or less, preferably 0.1 to 1.5 equivalents, relative to the equivalent of the secondary amino group of the component (a).

Components (a) and (b) obtained by various methods as described above
The reaction products of (c) and (c) are both dissolved in water and then reacted with formaldehyde. The reaction has a concentration of 20
~ 80% by weight, preferably 30-70% by weight in aqueous solution, pH
7 or less, preferably after being adjusted with an acid such as pH 3.5 to 6.5 with hydrochloric acid, sulfuric acid, phosphoric acid, formic acid, acetic acid, etc.,
It is carried out at a reaction temperature of 40 to 80 ° C. for 1 to 10 hours. This reaction is
Perform the reaction under acidic conditions as described above, but make sure that the pH of the reaction solution is 8
Perform the reaction under alkaline conditions such as ~ 12, and then adjust the pH to 7
The water-soluble thermosetting resin of the present invention can be obtained by adjusting the pH to 3.5 to 6.5, and then continuing the reaction. In this case, the reaction under alkaline temperature is 40 ~
The reaction is carried out at 80 ° C for 0.5 to 3 hours, and the reaction under acidic condition is performed at the temperature of 40 to 80 ° C for 1 to 10 hours. The amount of formaldehyde is component (c) 1
0.1 to 1.0 mol, preferably 0.2 to 0.7 mol is suitable for the mol. After completion of the reaction, the water-soluble thermosetting resin used in the present invention is obtained by adjusting the pH to 6 to 9 with caustic soda, caustic potash, etc., if necessary.

The resin thus obtained is obtained in the form of an aqueous solution, and the viscosity of the aqueous solution having a resin solid content of 50% by weight is usually 5 to 1000 centipoise (hereinafter abbreviated as cp) at 25 ° C. Is very low, the effect of addition of the resin as a paper coating composition tends to be low, and high viscosity, the viscosity of the prepared paper coating composition is generally high In practice, the viscosity range of 10 to 500 cp, particularly preferably 20 to 200 cp, is preferably used.

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

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

The composition ratio of the paper coating composition of the present invention is (I) Pigment 100
1 to 50 parts by weight of (II) aqueous binder, based on parts by weight,
Preferably 6 to 40 parts by weight, (III) Water-soluble thermosetting resin
It is 0.05 to 10 parts by weight, preferably 0.1 to 3 parts by weight. The solid content concentration of the coating composition is 20 to 75% by weight.

Generally, the water-soluble thermosetting resin (III) used in the present invention is added and mixed to the pigment and the aqueous binder during the preparation of the paper coating composition. Also, the effect of the present invention can be obtained.

The paper coating composition of the present invention requires a dispersant, a viscosity / fluidity modifier, an antifoaming agent, a preservative, a lubricant, a water retention agent, a dye, a colorant such as a colored pigment, and the like as other components. Can be blended accordingly.

Further, in the process of preparing the coating composition of the present invention, the mixing order of each component is not particularly limited, but dispersion stability as a composition decreases due to different ionicity and the like. Therefore, it is desirable to select and implement the order of blending, the solid content concentration of each component at the time of blending, the pH of the coating composition, and the like.

The paper coating composition of the present invention is a conventionally known method, that is, a blade coater, an air knife coater, a roll coater, a size press coater, a gate roll coater, a cast coater, etc. Coated paper can be produced by applying, performing necessary drying by a usual method, and further performing super calendering treatment if necessary.

<Effects of the Invention> The coated paper thus obtained using the coating composition for paper of the present invention is excellent in ink acceptability, water resistance, glossiness improvement, opacity improvement, blister resistance, and formaldehyde odor. It has various excellent and effective characteristics such as no occurrence of

The "paper" of the paper coating composition in the present invention has a broad meaning and includes a narrow meaning of paper and paperboard.

<Examples> Hereinafter, the present invention will be described in more detail with reference to Examples and Examples. All% and parts in the text represent% by weight and parts by weight.

Reference Example-1 (Synthesis of Water-Soluble Thermosetting Resin (III)) Triethylenetetramine 58.5 parts (0.4 mol) and urea 1 were placed in a four-necked flask equipped with a thermometer, a reflux condenser and a stirring rod.
2.0 parts (0.2 mol) was charged and heated at an internal temperature of 120 to 140 ° C. for 3 hours to carry out a deammonification reaction. After that, 34.4 parts (0.2 mol) of hexahydrophthalic acid was charged and the internal temperature was 150 to 160 ° C.
The dehydration amidation reaction was carried out for 5 hours. Then at the internal temperature
Cool to 130 ° C and charge 48.0 parts (0.8 mol) of urea at a temperature of 12
A deammonification reaction was performed at 0 ° C to 130 ° C for 2 hours. afterwards
After cooling to 100 ° C., water was added to make a 50% aqueous solution. Next, 32.4 parts (0.4 mol) of 37% formalin was added, and the pH of the system was adjusted to 5.1 with 70% sulfuric acid.

This was heated to 60 ° C and reacted for 5 hours, then cooled and neutralized with 28% caustic soda solution, product pH = 7.1, concentration 48.5%,
A resin liquid having a viscosity of 45 cp was obtained. This is referred to as resin liquid A.

Reference Example-2 Triethylenetetramine 58.5 in the same container as Reference Example-1
Part (0.4 mol) and urea 12.0 parts (0.2 mol) were charged and the internal temperature was 12
The mixture was heated at 0 to 140 ° C for 3 hours to carry out a deammonification reaction. Thereafter, 30.4 parts (0.2 mol) of tetrahydrophthalic anhydride was charged, and dehydration amidation reaction was carried out at an internal temperature of 150 to 160 ° C for 5 hours. Thereafter, the internal temperature was cooled to 130 ° C., 48 parts (0.8 mol) of urea was charged, and a deammonification reaction was performed at a temperature of 120 to 130 ° C. for 2 hours. Then, it was cooled to 100 ° C., and water was added to make a 50% aqueous solution. Then, 32.4 parts (0.4 mol) of 37% formalin was added and the pH of the system was adjusted to 5.0 with 70% sulfuric acid.

This was heated to 60 ° C and reacted for 4 hours, then cooled and neutralized with a 28% caustic soda aqueous solution to obtain product pH = 7.34, concentration 49.0%,
A resin solution having a viscosity of 52.1 cp was obtained. This is referred to as resin liquid B.

Reference Example-3 Tetraethylenepentamine 7 was placed in the same container as Reference Example-1.
5.7 parts (0.4 mol) and 12.0 parts (0.2 mol) of urea were charged and heated at an internal temperature of 120 to 140 ° C. for 3 hours to carry out a deammonification reaction. Then tetrahydrophthalic anhydride 30.4 parts (0.
(2 mol) was charged and a dehydration amidation reaction was performed at an internal temperature of 150 to 160 ° C. for 5 hours. After that, the internal temperature was cooled to 130 ° C and urea 24.
0 part (0.4 mol) was charged and a deammonification reaction was performed at a temperature of 120 to 130 ° C. for 2 hours.

Then, it was cooled to 100 ° C., and water was added to make a 50% aqueous solution. Then, 16.2 parts of 37% formalin (corresponding to 0.2 mol) was added, and the pH of the system was adjusted to 5.15 with 70% sulfuric acid. 60 ° C
The temperature was raised to and the reaction was carried out for 4 hours. Then, it was cooled and neutralized with a 28% aqueous sodium hydroxide solution to obtain a resin liquid having a product pH of 7.23 and a viscosity of 79.5 cp. This is referred to as a resin liquid C.

Reference Example-4 Triethylenetetramine 58.5 in the same container as Reference Example-1
Part (0.4 mol) and urea 12.0 parts (0.2 mol) were charged and the internal temperature was 12
The mixture was heated at 0 to 140 ° C for 3 hours to carry out a deammonification reaction. After that, HN-2200 (manufactured by Hitachi Chemical Co., Ltd., alicyclic acid anhydride, below formula) 33.2 parts (0.2 mol) were charged and a dehydration amidation reaction was carried out at an internal temperature of 150 to 160 ° C. for 5 hours. After that, the internal temperature was cooled to 130 ° C, and 12.0 parts (0.2 mol) of urea was charged, and the temperature was 120 to 130.
A deammonification reaction was carried out at 0 ° C for 2 hours. Then 100 ° C
The mixture was cooled to 50 ° C and water was added to make a 50% aqueous solution. Then 37%
8.1 parts of formalin (corresponding to 0.1 mol) was added, the pH of the system was adjusted to 5.0 with 70% sulfuric acid, the temperature was raised to 60 ° C, and the pH was adjusted to 4 at 60 ° C.
Reacted for hours. Then, it was cooled and neutralized with a 28% caustic soda solution to obtain a product. Product pH = 7.06, viscosity 52.0cp, concentration
A resin solution of 50.1% was obtained. This is referred to as resin liquid D.

Reference Example-5 In a container similar to Reference Example-1, 12.4 parts (0.2 mol) of ethylene glycol and 60.8 parts (0.4 mol) of tetrahydrophthalic anhydride were charged and heated at 140 ° C for 2 hours to produce a reaction having a free carboxyl group. I got a thing. Further urea 1 to this
2.0 parts (0.2 mol) was charged, and 58.5 parts (0.4 mol) of triethylenetetramine was added with stirring at 110 to 120 ° C.

This was subjected to deammonification reaction and dehydration amidation reaction at 150 ° C. for 5 hours. This is cooled to 130 ° C and urea 12.0 is added.
Part (0.2 mol) was added, and a deammonification reaction was performed at a temperature of 120 to 130 ° C. for 2 hours. Then, it was cooled to 100 ° C., and water was added to make a 50% aqueous solution. 37% formalin 8.1 parts (0.1
Mol) was added and the pH of the system was adjusted to 5.0 with 70% sulfuric acid, the temperature was raised to 60 ° C., and the reaction was carried out for 4 hours. Then cool
The product was neutralized with a 28% caustic soda solution.

A resin solution having a product pH of 7.23 and a viscosity of 43 cp was obtained. This is referred to as a resin liquid E.

Reference Example-6 Triethylenetetramine 29.2 in the same container as Reference Example-1
Part (0.2 mol) was charged, and 30.8 parts (0.2 mol) of hexahydrophthalic anhydride was added thereto, and the temperature was raised to 150-155.
Dehydration amidation was performed at ° C. Then cool to 130 ° C,
Charge 12 parts (0.2 mol) of urea and hold at 125-130 ℃ for 2 hours.
A deammonification reaction was performed. Then, this was cooled to 60 ° C., and water was added to dilute it to obtain a 50% aqueous solution. Then 37%
Add 8.1 parts (0.1 mol) of formalin and add 70% sulfuric acid to the system pH.
Was adjusted to 5.0 and reacted at 60 to 65 ° C for 4 hours.

After the reaction, it was neutralized with a 28% aqueous sodium hydroxide solution to adjust the product pH to 7.2. The product was a resin solution having a concentration of 47.9% and a viscosity of 36 cp. This is referred to as a resin liquid F.

Reference Example-7 According to Reference Example-1, triethylenetetramine 58.5 parts (0.4
Mol) and tetrahydrophthalic anhydride 30.4 parts (0.2
12 parts (0.2 mol) of urea was charged at the same time and the temperature was raised to 1
Dehydration amidation and deammonification reaction were simultaneously performed at 50 to 155 ° C. for 5 hours. Then, the mixture was cooled to 130 ° C., 12 parts (0.2 mol) of urea was further charged, and a deammonification reaction was carried out at 125 to 130 ° C. for 2 hours. Water was added to this to dilute it to obtain a 50% aqueous solution. Next, 37% formalin 8.1 parts (0.1 mol)
Then, add 70% sulfuric acid to adjust the pH of the system to 5.0.
The reaction was carried out at 5 ° C for 4 hours.

Then, it was cooled and neutralized with a 28% caustic soda aqueous solution to obtain a product.

A resin liquid having a product pH of 7.42 and a viscosity of 32 cp was obtained. This is referred to as a resin liquid G.

Reference Example-8 Triethylenetetramine 58.5 was placed in the same container as Reference Example-1.
14 parts (0.4 mol) and 12 parts of urea (0.2 mol) were charged, 145-1
The deammonification reaction was carried out at 50 ° C. for 4 hours. In another container, mix 60.8 parts (0.4 mol) of tetrahydrophthalic anhydride and 15.2 parts (0.2 mol) of propylene glycol,
Polyester was obtained by heating at 150 ° C. for 2 hours. The entire amount of this polyester was charged into a container in which the above deammonification reaction had been completed, and the internal temperature was heated at 150 to 155 ° C. for 4 hours for dehydration and deammonification reaction. Then cool to 130 ° C and add urea 1
2 parts (0.2 mol) was added and a deammonification reaction was carried out at 125 to 130 ° C. for 2 hours. Then add water to make 50% aqueous solution and 37%
Add 8.1 parts (0.1 mol) of formalin and adjust the pH with 70% sulfuric acid.
In accordance with 5.1, the reaction was carried out at 60 to 65 ° C for 4 hours, and this was cooled and neutralized with a 28% aqueous sodium hydroxide solution to give a product.

A resin solution having a product pH of 7.51 and a viscosity of 47 cp was obtained. This is called a resin liquid H.

Comparative Reference Example-1 According to Reference Example-1, except that 29.6 parts (0.2 mol) of phthalic anhydride was used in place of the hexahydrophthalic acid of Reference Example-1, the synthesis was carried out under the same raw materials and under the same conditions. As a result, a resin liquid having a product pH of 7.2 and a viscosity of 44 cp was obtained.

This is referred to as resin liquid I.

Comparative Reference Example-2 According to Reference Example-1, except that 29.2 parts (0.2 mol) of adipic acid was used instead of hexahydrophthalic acid in Reference Example-1, all were synthesized under the same raw materials and under the same conditions, and finally A resin liquid having a product pH of 7.01 and a viscosity of 66 cp was obtained.

This is referred to as a resin liquid J.

Comparative Reference Example-3 According to Reference Example-5, first, 58.5 parts (0.4 mol) of adipic acid.
And ethylene glycol 12.4 parts (0.2 mol) to 160-18
It was heated at 0 ° C. for 3 hours to be dehydrated and esterified to obtain a polyester having a carboxyl group at a terminal. Further urea
12.0 parts (0.2 mol) was added, and 58.5 parts (0.4 mol) of triethylenetetramine was added with stirring at 110 to 120 ° C. This was subjected to deammonification and dehydration amidation reaction at 150 ° C. for 5 hours. This was cooled to 130 ° C., 12.0 parts (0.2 mol) of urea was added, and a deammonification reaction was carried out at a temperature of 120 to 130 ° C. for 2 hours. Then, water was added to make a 50% aqueous solution. Then
8.1 parts (0.1 mol) of 37% formalin was added, the pH of the system was adjusted to 4.8 with 70% sulfuric acid, the temperature was raised to 60 ° C., and the reaction was carried out for 4 hours. Then, it was cooled and neutralized with a 28% caustic soda aqueous solution to obtain a product. A resin solution having a product pH of 7.25 and a viscosity of 96 cp was obtained. This is called a resin liquid K.

Examples 1 to 8 Water-soluble thermosetting resins (resin liquids A to
H) was used to prepare a paper coating composition having the composition shown in Table 1.

The adjusted paper coating composition has a total solid content of 60% and a pH of about 8.
Each was prepared with water and 10% caustic soda aqueous solution so that it would be 5, and then coated on one side of a high-quality paper with a wire basis weight of 80 g / m ^{2 so} that the coating amount would be 14 g / m ² . . Immediately after coating, dry with hot air at 120 ° C for 30 seconds, then 20
After humidity control at 65 ℃ and 65% RH for 16 hours, temperature 60 ℃, linear pressure 60Kg
Supercalendering was performed twice under the condition of / cm to obtain a coated paper. The coated paper thus obtained was tested for water resistance, ink acceptability, and formaldehyde determination. The test results are shown in Table 2 as Examples 1 to 8.

The test method is as follows.

○ Water resistance (a) Wet rub method Approximately 0.1 ml of ion-exchanged water was dropped on the coated surface, and the water was applied with a fingertip.
After rubbing once, the elution amount was transferred to black paper, and the elution amount was visually evaluated.

The criteria for judgment were as follows.

Water resistance (poor) 1 to 5 (excellent) (b) Wettopic method Using a PI tester, wet the coated surface with a water supply roll, then print, and observe the peeled state with the naked eye to check the water resistance (poor). ) 1
A judgment of ~ 5 (excellent) was made.

○ Ink acceptability (b) Method A A PI tester (Myo Seisakusho) was used to moisten the coated surface with a water supply roll, and then printing was performed to observe the ink acceptability.

The ink acceptability (poor) is 1 to 5 (excellent).

(B) Method B A PI tester was used to print while kneading water into the ink, and the ink acceptability was observed.

The ink acceptability (poor) is 1 to 5 (excellent).

○ Quantification of formaldehyde According to JIS-L1041-1976 liquid phase extraction method (2) acetylacetone method (method A), 2.5 g of coated paper sample was sampled and quantified.

Comparative Example 1-4 Resin liquids I to K obtained in Comparative Reference Examples 1 to 3 and Sumireze Resin 613 (water-soluble melamine manufactured by Sumitomo Chemical Co., Ltd.)
Formaldehyde resin) was used as a water-soluble thermosetting resin in the same coating composition for paper as in Examples 1 to 8, coated paper was prepared according to the same example, and the test results were also shown in Table 2. It was shown to.

Claims (1)

[Claims] 1. An (I) pigment, (II) aqueous binder, and (III) (a) polyalkylene polyamine, (b) alicyclic dibasic carboxylic acid and / or alicyclic dibasic carboxylic acid A paper coating characterized by containing a reaction product having a free carboxyl group obtained by reaction with glycols, (c) ureas, and (d) water-soluble thermosetting resin reacted with formaldehyde Composition.