JPS59137597A - Paper coating composition - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a coating composition for paper, and in particular to a coating composition that has excellent water resistance and ink transfer properties, is free from coloration, has excellent blister resistance, and does not generate any formaldehyde. The present invention relates to a paper coating composition capable of providing paper.

It has long been known to produce coated paper with excellent printability by coating paper with a paper coating composition that mainly consists of pigments and a water-based binder, and also contains auxiliary agents such as waterproofing agents. ing.

In recent years, there has been significant progress in coated paper manufacturing technology. For example, in order to increase productivity, the solid concentration in the coated paper is increased and coating is performed at high speed with a blade coater. The composition is required to have good coating properties and no increase in viscosity.

In addition, as printing becomes more sophisticated and faster, and rotary offset printing becomes more widespread, improvements in the water resistance, ink transferability, and blister resistance of coating layers are required.

In order to improve these performances, many proposals have been made in the past, such as modification of the aqueous binder component and improvement of the auxiliary component. For example, water resistance can be improved by increasing the amount of aqueous binder relative to the pigment, but on the other hand, ink transferability during printing decreases, so a method is generally used in which a water resistance agent is added as an auxiliary component.

A typical waterproofing agent in this case is a water-based binder waterproofing agent, but while all of the conventionally used or proposed waterproofing agents have effective advantages, they also have serious drawbacks. , which was not practically satisfactory.

For example, melamine-formaldehyde initial condensate has insufficient ink transfer properties to coated paper, and the pH of the coating composition
When this is high, there are problems such as insufficient water resistance and a large amount of free formaldehyde generated from the coated paper. In addition, the reaction product of polyamide polyurea and formaldehyde has an excellent effect on improving the ink transfer property of coated paper.
The water resistance is also good, and the amount of free formaldehyde generated from the coated paper is small, but not completely absent, and some free formaldehyde is observed to be generated.

Although dialdehydes such as glyoxal do not generate any free formaldehyde from the coated paper, they cause coloring of the coated paper and are inferior in their effect of improving ink transfer properties.

In order to improve these drawbacks, the present inventors have conducted intensive studies and found that a paper coating composition containing a thermosetting resin produced by a specific method as a water-resistant agent has improved water resistance and ink transfer. The present inventors have discovered that it is possible to provide a coated paper that has excellent properties and does not generate any free formaldehyde, and has completed the present invention.

That is, the present invention mainly contains a pigment and an aqueous binder, and further contains a resin obtained by reacting a polyamide polyurea obtained by reacting urea, a polyalkylene polyamine, and a dibasic carboxylic acid as raw materials with a dialdehyde. This is a paper coating composition characterized by the following.

The polyalkylene polyamine used in the present invention has two primary amino groups and at least one secondary amino group in the molecule, and includes, for example, diethylenetriamine, triethylenetetramine, and tetraethylene. Pentamine, iminobisbrobylamine, 8-azahexane-1,6-diamine, 4,7-diazadecane-1,
Examples include 10-diamine. These polyalkylene polyamines may be used alone or in combination of two or more.

Dibasic carboxylic acids used in the present invention include succinic acid, glitaric acid, adivic acid, sebacic acid, maleic acid, fumaric acid, aliphatic carboxylic acids, isophthalic acid, aromatic carboxylic acids such as terephthalic acid, Mention may be made of aromatic carboxylic acids such as isophthalic acid, terephthalic acid, and mixtures thereof.

Examples of dialdehydes used in the present invention include aliphatic dialdehydes such as glyoxal, malonaldehyde, succinic aldehyde, glutaraldehyde, and adipaldehyde, and aromatic dialdehydes such as isophthalic dialdehyde and phthalic dialdehyde. These dialdehydes may be used alone or in combination of two or more types, but glyoxal is particularly preferred.

The polyamide polyurea referred to in the present invention is, for example, a polyamide polyurea (hereinafter referred to as polyamide polyurea [ A) or a polyamide polyurea (hereinafter referred to as polyamide polyurea [B]) obtained by dehydration condensation of a polyalkylene polyamine and a dibasic carboxylic acid, followed by a deammonia reaction with urea.

In polyamide polyurea [A], the molar ratio of urea and polyalkylene polyamine is preferably around 1:2. The reaction temperature is suitably 100 to 200°C, preferably 120 to 170°C, and the reaction is carried out for 2 to 5 hours while removing effervescent ammonia from the system. Then, 0.8 to 0.0% per mole of polyalkylene polyamine.
Dehydration condensation with 7 mol of dibasic carboxylic acid. The reaction is carried out at a reaction temperature of 120 to 250°C, preferably 140 to 200°C, for 2 to 10 hours while removing generated water from the system. The condensation reaction product thus obtained is further reacted with urea. The amount of urea is 0.2 to 145 per mole of secondary amino group in the raw material polyalkylene polyamine.
mol, preferably 0.5 to 1.1 mol.

The reaction temperature is 100-180°C, preferably 120-15
The temperature is 0°C, and the reaction is carried out at this temperature for 1 to 5 hours while removing generated ammonia from the system. In this way, polyamide polyurea [A] is obtained.

Polyamide polyurea CB], the reaction between polyalkylene polyamine and dibasic carboxylic acid is carried out at a temperature of 120
The reaction is carried out at ~250°C, preferably 140-200°C, for 2-10 hours while removing the produced water from the system. The reaction is carried out at a molar ratio of 1.4 to 8.0 mol, preferably 1.8 to 2.5 mol, of polyalkylene polyamine per mol of dibasic carboxylic acid. The dehydration condensation reaction product thus obtained is then reacted with urea. The amount of urea used is 0.2 to 1.0 mol, preferably 0.4 to 0.8 mol, per mol of amino group in the raw material polyalkylene polyamine.
It is a mole. The reaction temperature is 100-180°C, but 1
A temperature of 20 to 150°C is suitable. The reaction is carried out at this temperature for 1 to 5 hours while removing the generated ammonia from the thread.

As a method of preparing urea, it is possible to charge the required amount all at once and perform the reaction.It is also possible to charge a portion of the required amount, complete the deammonification reaction, and then charge the remaining urea and perform the deammonification reaction again. . In this way, polyamide polyurea [B] is obtained.

The polyamide polyurea obtained as described above is dissolved in water and reacted with dialdehyde. The reaction is carried out at a concentration of polyamide polyurethane of 20 to 70% by weight, preferably 80 to 6%.
After adjusting the pH to 3 or less, preferably 4 or less in a 0% aqueous solution with an acid such as hydrochloric acid, sulfuric acid, phosphoric acid, formic acid, acetic acid, etc., at a reaction temperature of 40 to 80°C
The appropriate amount of dialdehyde for 10 hours is 0.01 to 2 mol, preferably 0.05 to 1 mol, per 1 mol of the total urea used to synthesize the polyamide polyurea.

After the reaction is completed, the pH of the reaction product is adjusted to 6-9, if necessary.

The paper coating composition of the present invention can be prepared in a conventional manner.

Generally, it is prepared by adding a water-resistant agent to a mixture of a pigment and a binder, but it is also possible to mix a water-resistant agent into a pigment slurry or an aqueous binder in advance and use this to prepare a coating composition. can. In order to fully exhibit the effect, the reaction product of polyamide polyurea and dialdehyde is usually blended in an amount of 0.05 to 5% by weight, preferably 0.1 to 2% by weight based on the weight of the pigment. Ru.

As the waterproofing agent, only those specified in the present invention are sufficiently effective, but depending on the case, it is also possible to replace a part of them with other waterproofing agents.

As the aqueous binder and pigment used in preparing the paper coating composition of the present invention, conventionally known ones can be used as they are.

Examples of water-based binders include starch,
．． Oxidized starch, modified starch, polyvinyl alcohol, casein, gelatin, carboxymethyl cellulose,
Examples include water-soluble binders such as hydroxyethyl cellulose and soybean protein, styrene-butadiene resins, vinyl acetate [1, water emulsion and dispersion systems such as ethylene-vinyl acetate resins, and methyl methacrylate resins].

Examples of pigments include inorganic pigments such as kaolin clay, talc, titanium dioxide, aluminum hydroxide, calcium carbonate, satin white, and barium sulfate, and organic pigments whose main components are styrene, urea, etc. These may be used alone or in combination of two or more in any proportion.

Other components of the paper coating composition of the present invention include dispersants, thickeners, thinners, antifoaming agents, foam inhibitors, preservatives, antifungal agents, flow regulators, release agents, dyes, Coloring agents such as colored pigments, special performance imparting agents such as conductive agents, etc. can also be blended as necessary.

Further, the concentration and other adjustment conditions of the coating composition of the present invention can be adjusted by conventional methods in exactly the same manner as conventional methods.゛The paper coating composition of the present invention can be coated onto a paper substrate by a conventionally known method, such as a blade coater, air knife coater, roll coater, size press coater, or cast coater. Coated paper can be produced by carrying out necessary drying using a conventional method, and further subjecting the paper to a treatment such as a super calender or a machine calender, if necessary.

The paper coating composition of the present invention thus obtained does not cause color shock (significant thickening of the composition, aggregation of pigments, etc.)
The coating liquid is excellent in stability, and the coated paper obtained by coating this on a paper substrate has excellent water resistance in the coating layer, and there is no formaldehyde generation (improved ink transfer properties). It has various excellent characteristics such as not being colored, and being effective in improving blister resistance in offset 1 and rotary printing.

The present invention will be explained below using reference examples and examples.

In the text, % represents weight % unless otherwise specified.

Reference example l [i1 Synthesis of resin (A) 292 g (2 mol) of triethylenetetramine and 60 g of urea were placed in a four-eye flask equipped with a thermometer, reflux condenser, and stirring bar.
f (1 mol) was charged and the reaction was carried out for 4 hours while removing ammonia generated from the system at 145-150°C. Next, 146 g (1 mol) of adipic acid was added and the mixture was heated at 150-150°C.
The condensation reaction was carried out at 55°C for 5 hours.

After cooling to 120°C, 240°C of urea was added. N (4 moles)
was added to carry out a deammoniation reaction at 125 to 180°C for 2 hours. Thereafter, 380 g of water was gradually added to obtain an aqueous solution of polyamide polyurea.

Next, 40% glyoxal aqueous solution 2901 (2 mol) was added, and after adjusting the pH to 8.0 with 50% sulfuric acid,
The mixture was stirred and kept warm at ℃ for 5 hours. The reaction solution was cooled to 25° C. to obtain a resin (A) with a solid content of 50%.

[i] Synthesis of resin (B) 206 g of diethylenetriamine (
2 mol) and urea 60f (1 mol), 140~1
Deammonia reaction was carried out at 45°C for 5 hours, then 9146 g (1 mol) of adivin was added and dehydration condensation was carried out at 160-170°C for 2 hours. After cooling to 120°C, urea 1201F (2 mol) was added, and ammonia removal reaction was carried out at 180 to 140°C for 1.5 hours. Then water 250
g was gradually added to obtain an aqueous solution of polyamide polyurea.

Next, 290g (2 mol) of 40% glyoxal aqueous solution
was added, the pH was adjusted to 8.5 with 37% hydrochloric acid, and then 7.
The mixture was stirred at 0° C. for 4 hours. The reaction solution was cooled to obtain a resin (B) with a solid content of 50%.

[rii] Triethylenetetramine 865f was added to the same apparatus as in synthesis (i) of resin (C).
(2.5 mol), water 201 and adipic acid 146 g (1
mol) was charged and subjected to dehydration condensation at 155 to 160°C for 4 hours. Next, add urea 60F (1 mol) to 145~
After performing the deammoniation reaction at 150°C for 8 hours, 18
The mixture was cooled to 0°C, 240 g (4 mol) of urea was added thereto, and ammonia removal reaction was carried out at 180 to 140°C for 8 hours. 280 liters of water was gradually added to obtain an aqueous solution of polyamide polyurea. Then 580g of 40% glyoxal aqueous solution
(4 mol) was added and the PR was adjusted to 8.5 with 50% sulfuric acid, followed by stirring at 65° C. for 5 hours to obtain a resin (0) with a solid content of 40 fins.

[iv] Synthesis of resin (D) An aqueous solution of polyamide polyurea was obtained in exactly the same manner as in (i).

Next, 25% glutaraldehyde aqueous solution 600N (1.
After adjusting pn=8.0 with 50% sulfuric acid, stirring was carried out at 70° C. for 5 hours to obtain a resin (D) with a solid content of 36%.

Reference Example 2 (1) Preparation of a coating composition for paper Kaolin clay, calcium carbonate, and aluminum hydroxide were used as pigments, a sodium polyacrylate-based dispersant was added, and a pigment slurry was dispersed in water. As an aqueous binder, a pre-gelatinized starch oxide aqueous solution,
and styrene-butadiene latex, and then add an appropriate amount of a waterproofing agent and mix well with stirring.Finally, the pH of the composition is adjusted to 9.5 with an aqueous caustic soda solution, and the solid content concentration is adjusted to 55. A paper coating composition was prepared by adjusting the weight%. The basic proportions in the composition are shown in Table 1.

(2) Preparation of coated paper The composition obtained by the above method is coated on a coated base paper with a basis weight of 851/tri using a coating rod at a dry solid content of about 15 f/tr on one side. Coat both sides so that 1
Hot air drying was performed at 20°C for 80 seconds. This coated paper was then supercalendered (roll temperature 60°C).
, Roll linear pressure 60Kg/Rust, 2 passes), 20°C, 6
Test samples were prepared in a 5% RH environment and subjected to various tests.

(8) Various test methods (A) Physical properties of coating liquid ■ pH of coating liquid Using glass electrode pH meter, measurement temperature 20°C ■ Viscosity of coating liquid Using B-type viscometer, rotation speed 6 Orpm, measuring temperature 20°C (B) Physical properties of coated paper ■Water resistance of coating film (a) WetRub method Approximately 0.1 mJ of ion-exchanged water is dropped onto the coated paper surface, rubbed 7 times with fingertips, and the eluted portion is transferred to the black paper and eluted. The amount was determined visually.

The evaluation criteria were as follows.

Water resistance (poor) 1-5 (excellent) (o) Using WetPick method RI testing machine (manufactured by Mei Seisakusho), the coated surface was moistened with a water supply roll and then printed, and the coated surface was not peeled off or damaged. The condition was visually observed and determined. The criteria for determination are the same as those for the WetRub method.

■Determination of formaldehyde from coated paper JI8L-10
41 Liquid phase extraction method (2) Based on the acetylacetone method The amount of formaldehyde was measured by sealing it in a polyethylene bag to prevent it from migrating or escaping.

(2) Ink transfer properties of coated paper Printing was performed using an RI tester according to the method described below, and the ink transfer properties were observed and judged with the naked eye.

The evaluation criteria were 5 to 1 (excellent) to 1 (poor).

(b) Method A Printing is done after dropping water onto the ink that is being mixed.

(b) Method B Print after moistening the surface to be coated with a water supply roll.

(c) C method Printing is performed by a combination of methods A and B described above.

■ Whiteness and heat resistance whiteness of coated paper Measure the whiteness of coated paper before and after heat treatment in a hot air dryer at 150°C for 80 minutes using a Hunter reflectance meter in accordance with JISP-8128. It was tested by

The larger the number, the better the whiteness.

■ Endurance, Bliss. Print on both sides of paper using off-ring ink using a thermal RI tester, and after adjusting the humidity, place it in a heated silicone oil bath to show the lowest temperature at which blisters occur. .

Examples 1 to 8 Using the resin obtained in Reference Example 1, evaluation was performed by the method shown in Reference Example 2. The resins used and their formulations are shown in Table 2.

The performance test results are shown in Table 2.

Comparative Examples 1 and 2 Coating liquids were prepared in the same manner as in the examples except that the resin obtained in Reference Example 1 was not used as a water-resistant agent, and performance evaluation was performed. Table 8 shows the formulation and performance test results.

Comparative Examples 8 to 8 As water-resistant agents, violet resin 618 (melamine-formaldehyde III JL manufactured by Sumitomo Chemical Co., Ltd.), violet resin 686 (polyamide polyurea-formaldehyde resin, manufactured by Sumitomo Chemical Co., Ltd.), and glyoxal were used. A coating liquid was prepared in the same manner as in the example, and performance evaluation was performed. Table 8 shows the layout and performance test results.

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Claims (1)

[Scope of Claims] (1) A polyamide polyurea obtained by reacting a pigment and an aqueous binder as main ingredients and further using urea, a polyalkylene polyamine, and a dibasic carboxylic acid as raw materials, and further reacting the obtained polyurea with a dialdehyde. 1. A paper coating composition comprising a resin. (2) The proportion of dialdehyde to be reacted with the polyamide polyurea is 0.01 to 2 moles per 1 mole of total urine used in producing the polyamide polyurea (claim 1) The paper coating composition described. (8) The paper coating composition according to claim 1, wherein the dialdehyde is glyoxal.