JP3156607B2 - Surface paper quality improver for neutral 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 surface paper quality improver which exhibits excellent effects on improving the surface strength, internal strength, water resistance and the like of neutral paper.

[0002]

2. Description of the Related Art In recent years, printing technology has been remarkably developed, and as printing speed and quality have increased, printing properties such as high surface strength, internal strength, and water resistance have been required for printing paper. It has become In order to meet these demands, chemicals are internally added (added to an aqueous slurry of pulp) or externally added (coated on the surface of paper). Of these, the internal additive does not have a sufficient yield of chemicals, and the external additive has almost 100% yield and acts directly on the paper surface.
It is known to be more advantageous.

[0003] Surface paper quality improvers applied to increase the surface strength of paper and improve printability include starches such as oxidized starch, celluloses such as carboxymethyl cellulose, and polyvinyl alcohol (hereinafter referred to as PVA). ) And natural or synthetic water-soluble polymers such as anionic polyacrylamide are used for surface coating, and oxidized starch is most frequently used. However, starches, P
VAs require a cooking step when used,
In addition to poor workability, there are various operational problems such as foaming and dirt during coating. In addition, the aqueous solutions of starches have a problem of spoilage and aging.

On the other hand, as the acrylamide resin, a monomer having a considerable solubility in water, such as acrylic acid or methacrylic acid or acrylonitrile, is used in combination with ordinary radical copolymerization in water,
Alternatively, a water-soluble polymer modified to a carboxyl group by partially hydrolyzing acrylamide after or before aqueous solution polymerization has been proposed as a surface treating agent for paper, mainly for the purpose of improving the surface strength (particularly). Kosho 43-27
529), but their surface strength, internal strength and water resistance are not sufficiently improved.

[0005] As a similar technique, a reinforcing agent for pulp products comprising a copolymer obtained by copolymerizing acrylamides with acrylonitriles and acrylic acids or alkali salts thereof in the presence of urea (Japanese Patent Publication No. 31240/1986)
However, this is an internal additive that is different from the external additive of the present invention. The internal additive causes clogging of the wire, impaired workability due to roll contamination, and wet product contamination due to blanket contamination. It has been proposed for the purpose of preventing picking and breakage. Therefore, it can be said that this is obviously different from the external additive which is applied after the paper layer of the present invention is formed and improves the surface strength, internal strength and water resistance of the paper.

[0006]

Under these circumstances, the above-mentioned existing surface paper quality improvers cannot be said to be sufficiently satisfactory with respect to the recent demand for advanced surface paper quality improvement. Improvements are needed for printing problems caused by insufficient strength, internal strength, and insufficient water resistance. In particular, no effective paper has yet been found for neutral paper, whose production has been increasing recently. Was desired.

[0007]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to meet the demand and found that acrylamides (a) and itaconic acid or its salts (b) are essential in the presence of ureas. When a surface paper quality improver composed of an acrylamide resin obtained by polymerization as a component is used alone or in combination with a water-soluble polymer, various surface paper qualities can be improved in a better balance than when the water-soluble polymer is used alone. Have been found to exhibit excellent effects on neutral paper, and have completed the present invention.

That is, according to the present invention, an acrylamide (a) and an itaconic acid or a salt thereof (b) are mixed in the presence of ureas in a weight ratio (a) / (b) of 98 to 85% by weight / 2 to 2%.
It is intended to provide a surface paper quality improver for neutral paper comprising an acrylamide resin obtained by polymerization at 15% by weight,

Also, selected from the group consisting of acrylamides (a), itaconic acid or its salts (b), and cationic monomers, nonionic monomers and anionic monomers other than (b) in the presence of ureas. (A) / (b) = 98 to 85% by weight / 2 to 15% by weight, and (a) + (b) / (c) = 9
It is intended to provide a surface paper quality improver for neutral paper comprising an acrylamide resin obtained by polymerizing at 9.5 to 80% by weight / 0.5 to 20% by weight,

Further, in the presence of ureas, acrylamides (a), itaconic acid or salts thereof (b), and a crosslinking agent (d) in a weight ratio of (a) / (b) = 98 to 85% by weight / 2.
１５15% by weight, and (a) + (b) / (d) = 99.9
An object of the present invention is to provide a surface paper quality improver for neutral paper comprising an acrylamide resin obtained by polymerizing at 95 to 95% by weight / 0.005 to 5% by weight.

Next, the present invention will be described in detail. The urea used in the present invention includes urea, thiourea, ethylene urea, etc., and urea is particularly preferred.

Acrylamides (a) include acrylamide and methacrylamide. Further, in addition to acrylamide and methacrylamide, N-ethyl (meth) acrylamide, N-methyl (meth) acrylamide, N, N-dimethyl (meth) acrylamide, N-isopropyl (meth) acrylamide, Nt-octyl (meth) ) N-substituted alkyl acrylamides such as acrylamide may be partially used.

The itaconic acid or its salt (b) includes itaconic acid and its sodium and potassium salts,
Ammonium salts and the like.

In addition to itaconic acid, polymerizable cationic monomers such as dimethylaminopropyl (meth) acrylamide and quaternary compounds thereof, or styrene, methyl vinyl ether in an amount not to impair the water solubility of the resin;
An alkyl ester of (meth) acrylic acid having 1 to 8 carbon atoms, 2-hydroxyester or glycidyl ester, acrylonitrile, or the like may be used in combination as a copolymer component.

The surface paper quality improver of the present invention exhibits excellent effects in improving the surface strength, internal strength, water resistance and the like of neutral paper, but is particularly excellent in improving the internal strength. Although the internal strength of neutral paper has been improved by internally adding polyacrylamides, the degree is insufficient. It is conceivable to supplement the performance of the internally added chemicals by external addition, that is, coating, but there has been no satisfactory performance in the past. The surface paper quality improver using the itaconic acid of the present invention completely satisfies the requirement regarding the internal strength of the neutral paper.

Other examples of the cationic vinyl monomer include 2-hydroxy-N, N, N, N ', N'-pentamethyl-N'-(3- (meth) acryloylaminopropyl) -1,3-propanediene. Ammonium dichloride,
2-hydroxy-N-benzyl-N, N-diethyl-
N ', N'-dimethyl-N'-(2- (meth) acryloyloxyethyl) -1,3-propanediammonium dibromide, N, N-dimethylaminoethyl (meth)
Acrylate, N, N-dimethylaminopropyl (meth) acrylamide, N-ethyl-N, N-dimethyl-
(2- (meth) acryloyloxyethyl) ammonium bromide, N-benzyl-N, N-dimethyl- (3
-(Meth) acryloylaminopropyl) ammonium chloride, diallylamine, vinylpyridine, vinylimidazole and the like.

As the crosslinking agent (d), any crosslinking agent conventionally used for polyacrylamide resins can be used. Examples include di (meth) acrylates such as ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, propylene glycol di (meth) acrylate, and triethylene glycol di (meth) acrylate, and methylene bis (meth) acrylate.
Bis (meth) acrylamides such as acrylamide, ethylenebis (meth) acrylamide, hexamethylenebis (meth) acrylamide, epoxy acrylates, divinylbenzene, urethane acrylates, diallyl phthalate, diallyl malate, triallyl cyanurate, triallyl Isocyanurate, dimethylol urea, dimethylol ethylene urea, other polymethylol urea, methylol ethylene urea, dimethylol glyoxal monourein, dimethylol glyoxal diurein, dimethylol uron, dimethylol propylene urea, 1,3-bis- ( (Hydroxymethyl) tetrahydro-5-hydroxy-2-pyrimidinone, dimethyloltriazone, dimethylolmelamine and other polymethylolmelamine, poly Polymethylol compounds such as Chi roll acetoacetate Guano thin and glyoxal, glutaraldehyde, polyaldehyde compounds such as dialdehyde starch, and the like.

The polymerization of the acrylamide-based resin of the present invention is carried out in the presence of a suitable polymerization initiator in the presence of ureas at 40 to 100.
C. at a reaction temperature of 1 to 10 hours. The weight ratio of urea / monomer is 5-60% / 95-40%, preferably 30-50% / 70-50%. It is not preferable that the amount of urea is larger or smaller than this range in terms of balance of surface strength, internal strength, water resistance and the like.

Known polymerization initiators are used.
As the radical polymerization initiator, a water-soluble catalyst such as sodium persulfate, potassium persulfate, ammonium persulfate, hydrogen peroxide, and ceric salt is used in an amount of 0.01 to 5% by weight based on the total weight of the monomers. Also, dimethylamine,
Redox polymerization can also be performed using a reducing agent such as sodium hydrogen sulfite or sodium formaldehyde sulfoxylate. Further, a known chain transfer agent may be used if necessary.

Examples thereof include allyl compounds such as allyl alcohol, allylamine and sodium allyl sulfonate, mercaptoethanol, thioglycolic acid or an alkali metal salt or ammonium salt thereof, isopropyl alcohol, and sodium hypophosphite.

The weight ratio of acrylamides (a) to itaconic acid or its salts (b) is 98-85% by weight / 2-
15% by weight. Further, when a cationic monomer, a nonionic monomer, and an anionic monomer (c) excluding (b) are used as the third component, the weight ratio is (a) +
(B) / (c) = 99.5-80% by weight / 0.5-20
% By weight, preferably 98 to 90% by weight / 2 to 10% by weight
It is. The weight ratio when the crosslinking agent (d) is used is (a)
+ (B) / (d) = 99.99 to 95% by weight / 0.0
05-5% by weight, preferably 99.95-97% by weight /
It is 0.05 to 3% by weight.

Acrylamides (a) in the presence of ureas
And an acrylamide-based resin obtained by polymerizing itaconic acid or a salt thereof (b) as an essential component may be used alone or in combination with a water-soluble polymer.

As the water-soluble polymer, starch, oxidized starch,
Examples include starch derivatives such as cationized starch, cellulose derivatives such as carboxymethyl cellulose, and polyvinyl alcohol.

The surface coating solution containing the neutral paper surface strength improver of the present invention may be prepared by adding acrylamides (a) in the presence of ureas.
And a mixed solution of an acrylamide-based resin and a water-soluble polymer obtained by polymerizing itaconic acid or a salt thereof (b) as an essential component.

The mixed solution is prepared by mixing an aqueous solution of an acrylamide resin and an aqueous solution of the water-soluble polymer, or by mixing an aqueous solution of the acrylamide resin and a dispersion of the water-soluble polymer and then cooking. Can be. The acrylamide-based resin may be mixed in any ratio, but is preferably 10% by weight or more from the viewpoint of improving the surface paper quality such as internal strength, surface strength and water resistance in a well-balanced and high degree.

A surface sizing agent, an anti-slip agent,
Additives such as preservatives, defoamers, viscosity modifiers, and dyes may be used in combination. The concentration of the coating solution is 0.2% to 10%, and the viscosity is 1% aqueous solution, and is 3 to 300 centipoise (c) at 25 ° C. and 60 rotations using a Brookfield M-type viscometer.
ps) is preferable, and 3 to 100 cps is most preferable for coating.

In order to apply the surface coating solution of the present invention to paper or paperboard, it is preferable to use a size press, a gate roll coater, a blade coater or a calender. The coating can also be carried out using a bar coater, knife coater, air-knife coater, or the like.

The coating solution of the present invention can be applied to various base papers such as coated base paper, newsprint, liner, coated ball, printed writing paper, foam paper, PPC paper, inkjet paper, and thermal paper. Of these various base papers, especially when applied to neutral paper, the paper quality improving effect is excellent. The sizing degree of the base paper is also arbitrary, but when coating is performed using a size press or the like, it is desirable to use an internal sizing agent for the purpose of adjusting the liquid absorption of the base paper.

[0029]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to examples, but the present invention is not limited by these examples. For convenience, monomers and the like are abbreviated as follows.

AAm: acrylamide IA: itaconic acid AMPS: 2-acrylamido-2-methylpropanesulfonic acid sodium AN: acrylonitrile AAc: acrylic acid The measurement was carried out according to the following method.

Internal strength: Scott bond method; measured using an internal bond tester (manufactured by Kumagai Riki Kogyo Co., Ltd.) under conditions of an adhesive pressure of 1 kg / cm ² and 30 seconds. Surface strength: dry pick; RI printing tester, nip width 1
0 mm, ink; FINE INK. (Dai Nippon Ink & Chemicals, IGT printing suitability test) V. =
18 Wet pick; RI printing tester, nip width 10mm
Molton roll used, ink; TPS of CAPS G (made by Dainippon Ink and Chemicals, offset) ink V. =
8 In all cases, the peeling state after printing was visually observed, and a five-point evaluation was performed with 5 being excellent and 1 being poor.

Production Example 1 484 g of water and urea 1 were placed in a 1-liter four-necked flask equipped with a stirrer, thermometer, reflux condenser and nitrogen gas inlet.
23.5 g (urea is 40% by weight of the total of urea and monomer), 50% aqueous acrylamide solution 344.4 (96 m
g), 13.1 g (4 mol%) of itaconic acid and 0.86 g of sodium methallylsulfonate, and 1.44 g of a 20% aqueous ammonium persulfate solution were added. Allowed to react for hours.

32.3 g of ion-exchanged water was added to the obtained polymer.
And 29.3% solids, viscosity 8050 cps, p
A clear aqueous solution of H6.8 was obtained. This is designated as resin A.
Further, in Production Example 1, polyacrylamide resins B to C and a to e were produced by appropriately changing the type of the monomer, the amount used, the amount of the initiator, and the like, and the physical properties thereof are shown in Table 1.
In Table 1, the viscosity is 25 ° C. using a Brookfield viscometer.
It is a measured value in.

[0034]

EXAMPLES Examples 1 to 3 The aqueous resin solutions A to C synthesized in Production Examples were diluted with water, and a surface sizing agent HARCON S20 (a surface sizing agent manufactured by Dick Hercules) was added thereto to obtain a solid content of 1.75. % Solution (0.1% by weight of Harcon S20 to solution) was prepared.

The diluted solution was diluted with neutral high-quality paper (basis weight: 77.0 g
/ Cm ² ]), using a test size press (manufactured by Kumagai Riki Kogyo Co., Ltd.) to perform double-side coating (nip pressure 20 kg / cm, coating speed 100 m / min, coating temperature 50 ° C.), and a drum dryer at 80 ° C. Drying was performed for 50 seconds. The coating amount is 0.
65 ± 0.03 g / m ² . After drying, 20 ° C, 65
The sample was left for 24 hours in a constant temperature / humidity room at a constant RH and then subjected to a test. The test results are shown in Table 2.

Comparative Examples 1 to 6 Cooked MS-3800 (oxidized starch manufactured by Nippon Shokuhin Kako Co., Ltd.) and aqueous resin solutions a to
Coating and testing were performed using the same method as in Example 1 except that e was used. The coating amount is 0.65 ± 0.03 g /
m ² . The test results are shown in Table 2.

[0037]

[Table 1]

[0038]

[Table 2]

[0039]

The present invention provides a surface paper quality improver for neutral paper which can improve various surface paper quality of neutral paper by external addition which is particularly desired. It can be said that the industrial effect is great.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-5-302298 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) D21H 19/20 D21H 21/20

Claims (3)

(57) [Claims] 1. An acrylamide (a) and an itaconic acid or a salt thereof (b) are polymerized in the presence of ureas in a weight ratio (a) / (b) of 98 to 85% by weight / 2 to 15% by weight. A surface paper quality improver for neutral paper comprising an acrylamide-based resin obtained by the above method. 2. The composition is selected from the group consisting of acrylamides (a), itaconic acid or salts thereof (b), and cationic monomers, nonionic monomers and anionic monomers other than (b) in the presence of ureas. (A) / (b) = 98 to 85% by weight / 2 to 15% by weight, and (a) + (b) / (c) = 9
A surface paper quality improver for neutral paper comprising an acrylamide resin obtained by polymerizing at 9.5 to 80% by weight / 0.5 to 20% by weight. 3. A acrylamide (a), itaconic acid or a salt thereof (b), and a crosslinking agent (d) in the presence of a urea in a weight ratio of (a) / (b) = 98 to 85% by weight / 2
１５15% by weight, and (a) + (b) / (d) = 99.9
A surface paper quality improver for neutral paper comprising an acrylamide resin obtained by polymerization at 95 to 95% by weight / 0.005 to 5% by weight.