JPH093797A - Paper processing agent - Google Patents

Abstract

PURPOSE: To obtain a paper processing agent excellent in stability over a long period time, having such effects as to improve the physical properties (esp. stiffness) of paper, by adding a crosslinking agent to the main component, i.e., an acetoacetic ester group-contg. polyvinyl alcohol-based resin. CONSTITUTION: A kneader is charged with polyvinyl alcohol-powder containing sodium acetate, which is then admixed with acetic acid to effect swelling of the powder; the temperature of the system is then raised under agitation and a mixture of diketene and acetic acid is dripped onto the system to proceed a reaction; after completing the reaction, the system is washed with methanol, and then dried to obtain a polyvinyl alcohol-based resin containing acetoacetic ester group with a sodium acetate content of <=2 (pref. <=0.5) wt.%, acetic acid content of <=5 (pref. <=2) wt.% and the weight ratio of the acetic acid to the sodium acetate of 0.01-100 (pref. 0.5-10). The resin is then formulated with a crosslinking agent such as glyoxal to obtain the objective paper processing agent. The pH value of a 4wt.% aqueous solution of the paper processing agent is adjusted to 3-6.5 (pref. 4-5) to prepare a coating liquid, which is applied to a paper substrate.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a paper processing agent containing a polyvinyl alcohol (hereinafter abbreviated as AA-PVA) -based resin containing an acetoacetic acid ester group as a main component, and more specifically, excellent in stability over time, and The present invention relates to a paper processing agent capable of obtaining paper having improved paper physical properties, particularly rigidity (stiffness).

[0002]

2. Description of the Related Art With the recent technological innovation and the advent of the age of resource saving and energy saving, attention has been paid to the so-called paper thinning, which reduces the amount of pulp used as much as possible. However, since such thin paper has a weak stiffness and has various practical effects, it is necessary to perform some treatment in order to increase the rigidity of the thin paper and to make it stiff. Therefore, conventionally, an aqueous solution of a polyvinyl alcohol (hereinafter abbreviated as PVA) -based resin or the like, or a method of applying a combination of this and a cross-linking agent to paper has been performed. However, since PVA-based resins have poor water resistance, PVA (hereinafter abbreviated as AA-PVA) -based resins containing an acetoacetic acid ester group have recently been investigated in order to improve water resistance. For example, in Japanese Unexamined Patent Publication No. 1-156597, AA PV
It has been proposed that by using an aqueous solution containing A and a zirconium salt, the rigidity of the paper is improved and the pot life of the coating liquid is extended.

[0003]

However, in the technique disclosed in the above publication, although the pot life of the coating solution is improved to some extent by 24 hours or more as compared with the examples, the coating solution can be stored for a long time such as several days. In some cases, it was found that the coating property may decrease due to the increase in the viscosity of the aqueous solution, and the physical properties of the coated paper tend to vary, and there is still room for improvement. Therefore, although the technology disclosed in the above publication is improved in terms of paper stiffness and short-term stability of the coating liquid, the stability of the aqueous solution for a long period of several days as described above and the obtained coating liquid are obtained. Since there is concern about the stability of the physical properties of the liquid, further improvement is indispensable in order to satisfy the required performance with the recent advancement of technology.

[0004]

Means for Solving the Problems As a result of intensive studies made by the present inventors in view of such circumstances, the alkali metal acetate is 2 wt% or less, the acetic acid is 5 wt% or less, and the alkali metal acetate is AA-PVA-based resin composition containing an alkali metal acetate and acetic acid in a ratio such that the weight ratio of / acetic acid is 0.01 to 100, preferably the alkali metal acetate is 0.1.
Mainly composed of AA-PVA-based resin containing 5% by weight or less, 2% by weight or less of acetic acid, and a ratio of alkali metal acetate / acetic acid of 0.1 to 10 in weight ratio of alkali metal acetate and acetic acid. The present invention has been completed by finding that the paper-processing agent as a component can achieve the above-mentioned object, that is, the improvement of the paper stiffness and the long-term stability of the coating liquid. In the present invention, it is preferable to use a crosslinking agent together in order to increase the rigidity of the paper.

Hereinafter, the present invention will be described in detail. The AA-PVA-based resin of the present invention is produced by any method such as a method of reacting PVA with diketene, a method of reacting PVA with acetoacetate ester for transesterification, or a method of copolymerizing vinyl acetate with vinyl acetoacetate. Although it is good, it is preferable to manufacture by a method of reacting PVA and diketene because the manufacturing process is simple and a good quality AA-PVA-based resin can be obtained. As a method of reacting PVA powder with diketene, PVA may be directly reacted with gaseous or liquid diketene, or after PVA is adsorbed and occluded with PVA in advance, liquid or gaseous under an inert gas atmosphere. The method of spraying and reacting the above-mentioned diketene or spraying and reacting PVA with a mixture of an organic acid and liquid diketene is used.

The PVA-based resin which is the starting material of the present invention has PVA obtained by saponifying a lower alcohol solution of polyvinyl acetate with a saponification catalyst such as alkali, and has a copolymerizability with vinyl acetate. A saponified product of a copolymer of a monomer and vinyl acetate can be used.

Examples of the monomer include ethylene, propylene, isobutylene, α-octene, α-dodecene,
Olefins such as α-octadecene, acrylic acid, methacrylic acid, crotonic acid, maleic acid, maleic anhydride,
Unsaturated acids such as itaconic acid or salts thereof or mono- or dialkyl esters, nitriles such as acrylonitrile and methacrylonitrile, amides such as acrylamide and methacrylamide, olefins such as ethylenesulfonic acid, allylsulfonic acid and methallylsulfonic acid Sulfonic acid or its salt, alkyl vinyl ethers,
N-acrylamidomethyltrimethylammonium chloride, allyltrimethylammonium chloride, dimethyldiallylammonium chloride, dimethylallyl vinyl ketone, N-vinylpyrrolidone, vinyl chloride, vinylidene chloride, polyoxyethylene (meth) allyl ether, polyoxypropylene (meth) allyl Polyoxyalkylene (meth) allyl ether such as ether, polyoxyethylene (meth) acrylate, polyoxyalkylene (meth) acrylate such as polyoxypropylene (meth) acrylate, polyoxyethylene (meth) acrylamide, polyoxypropylene (meth ) Polyoxyalkylene (meth) acrylamides such as acrylamide, polyoxyethylene (1- (meth) acrylamide-1,1-dimethyl) Propyl) ester, polyoxyethylene vinyl ether, polyoxypropylene vinyl ether, polyoxyethylene allylamine, polyoxypropylene allylamine, polyoxyethylene vinylamine, copolymerization saponified polyoxypropylene vinyl amine.

As a reaction apparatus for carrying out AA (acetoacetic acid ester) conversion, an apparatus capable of heating and equipped with a stirrer is sufficient. For example, a kneader, a Henschel mixer, a ribbon blender, other various blenders, and an agitating / drying device can be used.

In the AA-PVA-based resin of the present invention,
It is possible to adjust acetic acid and alkali metal acetates (sodium acetate, potassium acetate, etc.) to the amounts specified in the present invention.
This is the greatest feature. That is, it is necessary that the alkali metal acetate is contained in an amount of 2% by weight or less, preferably 0.5%.
It is not more than 0.1% by weight, preferably not more than 0.1% by weight. If the amount of the alkali metal acetate exceeds 2% by weight, the viscosity of the coating solution increases and the coatability decreases, which is not preferable.

As a method for quantifying the alkali metal acetate used in the present invention, after ashing PVA, a solution obtained by dissolving the ash in a hydrochloric acid aqueous solution under heating is performed by an atomic absorption method. Acetic acid must be contained in an amount of 5% by weight or less,
It is preferably 2% by weight or less, and more preferably 0.5% by weight or less. If the amount of acetic acid exceeds 5% by weight, a coated paper having sufficient rigidity cannot be obtained, which is not preferable. The acetic acid used in the present invention is determined by gas chromatography / mass spectrometry (GC / MS method).

The content of the alkali metal acetate and acetic acid should be controlled so that the final product falls within the scope of the present invention, and the timing of the control is arbitrary. For example, it is optional to adjust the amount of the alkali catalyst used in saponification when producing the raw powder PVA, to add or remove the alkali metal acetate after PVA production. Regarding the amount of acetic acid, it is also possible to add acetic acid after PVA production or to wash and dry PVA containing a large amount of acetic acid. In addition to the bulk powder treatment, AA PV
During or after the production of the A-based resin, an alkali metal acetate is added or removed, or acetic acid is removed or added,
You may take control. Industrially AA PVA
A method of removing the alkali metal acetate and acetic acid after the production of the base resin is practical.

To remove the alkali metal acetate, the AA-PVA resin is treated by a method such as alcohol washing. Alcohol cleaning is preferably used as the treatment method. As alcohols, methanol, ethanol, n-
Propanol, isopropanol and the like are used, but methanol is preferably used. In this case, the methanol washing uses 1 to 15 times the weight of PVA at 5 to 60 ° C.
It may be washed about 1 to 3 times in 0.5 to 2 hours.

In order to remove acetic acid, the AA-PVA resin is treated by a method such as distillation under reduced pressure, washing with methanol, drying treatment, filtration and centrifugation. These treatments may be performed simultaneously or separately. A drying treatment is preferably used as the treatment method. Drying conditions vary depending on the device, but are 30-
It may be carried out at 80 ° C. for about 10 hours, preferably 40 to
Perform at 70 ° C. for about 3 to 6 hours.

The weight ratio of the alkali metal acetate / acetic acid must be 0.01 to 100, and preferably,
It is 0.1 to 10. When the weight ratio is less than 0.01, it is difficult to obtain a paper having sufficient rigidity, and when it exceeds 100, the viscosity of the coating solution increases and the coating property deteriorates, which is not preferable.

In the present invention, when the pH of a 4% by weight aqueous solution of the composition is adjusted to 3 to 6.5, preferably 4 to 5, the stability of the physical properties of the coated paper and the viscosity stability of the coating liquid are further improved. It was also found to be good. If the pH is less than 3, or if it exceeds 6.5, sufficient rigidity cannot be obtained.
Thickening of the coating liquid will occur.

The pH control may be carried out so that the pH of the 4% by weight aqueous solution of the final product falls within the range of the present invention, and the timing of the control is arbitrary. For example, adjusting the amount of alkali catalyst at the time of saponification when producing bulk PVA, adding acetic acid after PVA production,
Any of them may be removed. If necessary, hydrochloric acid,
Sulfuric acid, mineral acids such as phosphoric acid, or propionic acid, organic acids such as maleic acid, sodium hydroxide, potassium hydroxide,
The pH may be adjusted by adding calcium hydroxide, primary amine, secondary amine, tertiary amine, quaternary ammonium salt or the like. In addition to the bulk powder treatment, AA PV
The above pH adjustment may be performed during or after the production of the A-based resin.

Thus, the AA-PVA obtained by the above method
Resins are used as paper processing agents, but AA
The PVA used for obtaining the modified PVA-based resin is not particularly limited, but from the viewpoint of the action and effect as a paper processing agent, the average degree of polymerization is 50 to 6000, preferably 100 to 400.
0, more preferably 300-2000, saponification degree 70-
It is desired that the amount is 100 mol%, preferably 80 to 100 mol%, and more preferably 85 to 100 mol%. A
The degree of AA conversion of the A-modified PVA-based resin is 0.01 to 30 mol%,
It is preferably 0.05 to 20 mol%, more preferably 0.1.
1 to 15 mol% is desirable, and AA degree is 0.0
Sufficient rigidity cannot be obtained with less than 1 mol% AA-PVA resin, while AA-PV PV resin with an AA-degree exceeding 30 mol%.
On the contrary, the A-based resin lowers the rigidity of the paper and is not preferable from the viewpoint of the stability of the coating liquid.

When the AA-PVA-based resin of the present invention is used as a paper processing agent, examples of cross-linking agents include glyoxal, methylolmelamine, potassium persulfate, ammonium persulfate, sodium persulfate, ferric chloride and magnesium chloride. , Metal salts such as calcium chloride, aluminum sulfate, magnesium sulfate, ammonium chloride, formalin,
Glycine, glycidyl ester, glycidyl ether,
Dimethylol urea, ketene dimer, boric acid, borax, zirconium alkoxide, zirconium ammonium carbonate, zirconium chloride, zirconium acetate, zirconium nitrate, zirconium sulfate and other zirconium salts, dialdehyde, starch, melamine resin, polyamide resin, polyamide-epiflorhydrin It is preferable to use a resin, a ketone-aldehyde resin, a polyethyleneimine resin or the like in combination.

When the crosslinking agent is used in combination, AA-PVA is used.
AA-based PVA-based resin 100
0.01 to 100 parts by weight, preferably 0.05 to 50 parts by weight, more preferably 0.1 to 30 parts by weight, or coated before or after coating with the AA-PVA-based resin. It is possible to perform any auxiliary operation such as If the blending amount of the cross-linking agent is less than 0.01 parts by weight, it is difficult to obtain sufficient rigidity, and if it exceeds 100 parts by weight, the rigidity decreases, which is not preferable.

There is no particular limitation on the preparation of the coating liquid,
Also, the concentration may be appropriately adjusted according to the purpose,
A particularly preferable concentration is 0.1 to 2 in consideration of coatability and the like.
0% by weight, more preferably 0.5 to 10% by weight,
The coating amount is 0.1 to 5 g / m ² , preferably 0.3 to 3 g / m ² .
m ² g is suitable.

The paper processing agent of the present invention may further contain known additives such as antifoaming agents, release agents, surfactants, preservatives, insect repellents, rust preventives, thickeners and pigments, if necessary. May be added, and other resins such as conventional PVA, starch, carboxymethyl cellulose, and
Acrylic latex, SBR latex and the like can also be mixed.

The paper to which the paper finishing agent of the present invention is applied is not particularly limited. For example, paperboard such as Manila balls, white balls, liners, etc., printing paper such as general fine paper, gravure paper, etc.,
Various recording papers such as inkjet paper are preferably used.
In coating the paper with the paper processing agent, any known method such as a size press coating, a roll coater method, an air doctor method, a blade coater method, or a gate roll method is adopted. Of course, not limited to these methods, the components constituting the present invention are dissolved in a pulp dispersion to make paper, so-called internal sizing method, or further powdery or fibrous components of the present invention are mixed into the paper. The paper finishing agent can be applied to the paper by any method.

[0023]

[Working] The paper-processing agent of the present invention is a specific AA-PVA
Since a system resin is used, especially when a crosslinking agent is also used, it is possible to provide a paper in which the temporal stability of the coating liquid and the rigidity of the paper are remarkably improved.

[0024]

EXAMPLES The present invention will be described in more detail below with reference to examples. In the examples, "part" and "%" mean weight basis unless otherwise specified. (Production of AA-PVA-based resin) AA-PVA (I) to (VIII) were produced by the following method. [AA-PVA (I)] PVA powder containing 0.3% of sodium acetate (saponification degree: 99.4 mol%, polymerization degree: 12)
00, average particle size 100 mesh) was charged into a kneader in an amount of 100 parts, and 60 parts of acetic acid was added to the kneader to swell, and the rotation speed was 2
While stirring at 0 rpm, raise the temperature to 60 ° C. and then diketene 2
A mixture of 5 parts and 2 parts of acetic acid was added dropwise over 4 hours, and further 3
The reaction was performed for 0 minutes. After completion of the reaction, the reaction mixture was washed with 500 parts of methanol, dried at 70 ° C. for 6 hours, and sodium acetate of 0.
AA-modified PV containing 05% and 0.1% acetic acid (sodium acetate / acetic acid weight ratio = 0.5) and having a degree of AA conversion of 6.0 mol%.
A resin was obtained. The pH of a 4% aqueous solution of this AA-PVA-based resin was 4.5.

[AA-PVA (II)] 100 parts of PVA powder containing 0.3% of sodium acetate (saponification degree: 88 mol%, polymerization degree: 1300, average particle size: 200 mesh) was charged into a kneader, and the rotation speed was 60 rpm. While stirring at 15, 15 parts of liquid diketene was added by spraying at room temperature for 30 minutes, and then the temperature was raised to 60 ° C. to react for 3 hours. After the reaction,
After washing 3 times with 50 parts of methanol, 0.05 part of sodium acetate was added, and then dried at 60 ° C. for 8 hours,
2. Containing 0.05% of sodium acetate and 0.01% of acetic acid (weight ratio of sodium acetate / acetic acid = 5), degree of AA conversion of 3.
3 mol% of AA-PVA-based resin was obtained. This AA PV
The pH of the 4% aqueous solution of the A-based resin was 4.8.

[AA-PVA (III)] PVA powder containing 0.3% of sodium acetate (saponification degree: 88 mol%,
A kneader was charged with 100 parts of a polymerization degree of 1300 and an average particle size of 100 mesh), and 8 parts of diketene gas generated in the evaporator was put in the reactor while heating to 90 ° C. for 1 hour under stirring at a rotation speed of 20 rpm. Let it flow. After heating to 90 ° C., stirring for another 30 minutes, 5 parts of water and 10 parts of acetic acid were sprayed and mixed, and dried under reduced pressure (100 mmHg) at 60 ° C. for 8 hours to obtain 0.1% sodium acetate and acetic acid. Containing 2% (sodium acetate / acetic acid weight ratio = 0.05), AA
An AA-PVA-based resin having a degree of chemical conversion of 3.1 mol% was obtained. This A
The pH of a 4% aqueous solution of the A-PVA-based resin was 3.5.

[AA-PVA (IV)] The above-mentioned AA-PV
In the production of A (I), washing with 500 parts of methanol was added once more, and the drying condition was reduced pressure (10 mmHg).
Produced in the same manner except that the temperature was changed to 70 ° C. for 6 hours, and contained 0.0075% sodium acetate and 0.001% acetic acid (sodium acetate / acetic acid weight ratio = 7.5), and had an AA degree of 3.
1 mol% of AA-PVA-based resin was obtained. This AA PV
The pH of a 4% aqueous solution of the A-based resin was 5.8.

[AA-PVA (V)] The above-mentioned AA-PV
In the production of A (I), the same procedure was performed except that the amount of methanol was changed to 100 parts and the drying condition was changed to 40 ° C. for 6 hours, and 0.2% sodium acetate and 5.3% acetic acid were added ( Sodium acetate / acetic acid weight ratio = 0.04), AA
An AA-PVA-based resin having a degree of chemical conversion of 6.0 mol% was obtained. This A
The pH of a 4% aqueous solution of the A-modified PVA-based resin was 2.8.

[AA-PVA (VI)] The above-mentioned AA-PV
In the production of A (I), the drying condition is under reduced pressure (100 m
mHg) The same procedure was performed except that the temperature was changed to 70 ° C. for 6 hours, and sodium acetate 0.2% and acetic acid 0.001% were included (sodium acetate / acetic acid weight ratio = 200), and the degree of AA conversion was 6.0 mol. % Of AA-PVA-based resin was obtained. The pH of a 4% aqueous solution of this AA-PVA-based resin was 5.8.

[AA-PVA (VII)] The above-mentioned AA-P
In the production of VA (I), after the completion of the AA reaction, 3.0 parts of sodium acetate was added and stirred, and the drying process was performed under reduced pressure (100 mmHg) at 60 ° C. for 3 hours. , Sodium acetate 2.2%, acetic acid 0.
25% (sodium acetate / acetic acid weight ratio = 8.
8), AA-PVA-based resin having a degree of AA of 6.0 mol% was obtained. The pH of a 4% aqueous solution of this AA-PVA-based resin is 4.
It was 0.

[AA-PVA (VIII)] 100 parts of PVA powder containing 0.1% sodium acetate (saponification degree 99.5 mol%, degree of polymerization 1200, average particle size 200 mesh) was charged in a kneader, To 30 parts of acetic acid, 30 parts of methyl acetoacetate and 2 parts of sulfuric acid were added, and the mixture was reacted at 80 ° C. for 8 hours with stirring. After completion of the reaction, it was washed with 50 parts of methanol, dried at 60 ° C. for 4 hours, and sodium acetate of 0. 02
%, Acetic acid 4% (sodium acetate / acetic acid weight ratio =
0.005), and an AA-modified PVA resin having a degree of AA of 6.0 mol% was obtained. P of 4% aqueous solution of this AA-PVA-based resin
H was 2.5.

Example 1 100 parts of AA-modified PVA (I) and Zircozol ZC (zirconium acid chloride-based: manufactured by Daiichi Rare Element Chemical Industry Co., Ltd.) 5
A 6% aqueous solution containing 1 part and 60 g / m ² of fine paper,
Size press coating was performed under conditions of a coating speed of 90 m / min and a coating pressure of 11 kg / cm ² so that the coating amount was 2 g / m ² (solid content conversion). After that, it was dried at 110 ° C for 2 minutes and treated with a super calender (40kg / cm
² , twice, at 80 ° C.). The rigidity of the obtained paper and the temporal stability of the coating liquid were evaluated as follows.

(Paper Stiffness) Measurement was carried out by a Clark stiffness tester (according to TAPPI standard method T-451). (Stability of coating liquid over time) The coating liquid was placed in a constant temperature bath at 30 ° C., the viscosity (b) after standing for 72 hours was measured, and the magnification (b / a) with respect to the initial viscosity (a) was calculated. .

Examples 2 to 9 and Comparative Examples 1 to 4 Experiments were carried out according to the method of Example 1 using the AA-PVA-based resin and the crosslinking agent shown in Table 1. The rigidity of the obtained paper and the temporal stability of the coating liquid were evaluated in the same manner as in Example 1. Table 1 shows the evaluation results of the examples and comparative examples.

[0035]

[Table 1] Stiffness of AA-PVA cross-linking agent paper Stability of coating liquid Part (cm ³ ) (times) Example 1 (I) Silcosol ZC 5 58 1.2 〃 2 (II) Glyoxal 0.5 54 1.1 〃 3 (III) Glyoxal 20 57 57 1.3 〃 4 (IV) Glyoxal 5 58 1.2 1.2 〃 5 (I) Glyoxal 5 58 1.2 1.2 〃 6 (I) Silkosol ZN 5 〃 1 56 (I) Silcosol ZA 5 56 1.3 〃 8 (I) Silkosol ZS 5 56 1.3 〃 9 (I) Dimethylol urea 5 57 1.2 Comparative Example 1 (V) Silkosol ZC 5 51 1.4 〃 2 (I) VI) Glyoxal 5 54 5.0 〃 3 (VII) Glyoxal 5 54 7.0 7.0 〃 4 (VIII) Glyoxal 5 50 1.2 Note) The compounding amount of the crosslinking agent is 100 parts of AA-PVA. It is a quantity for. Crosslinking agent: Zircozole ZC (zirconium acid chloride-based: manufactured by Daiichi Rare Element Chemical Industry Co., Ltd.) Zircozole ZN (zirconium nitrate-based: manufactured by Daiichi Rare Element Chemical Industry Co., Ltd.) Silcosol ZA (zirconium acetate-based: No. Gircozole ZS (manufactured by Ichiki Elementary Chemical Industry Co., Ltd.)

[0036]

The paper processing agent of the present invention is a specific AA-modified PV.
Since the A-based resin composition is used, especially when a cross-linking agent is also used, it is possible to provide a paper in which the temporal stability of the coating liquid and the rigidity of the paper are remarkably improved, which is extremely useful industrially. .

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location C08L 29/04 LGP C08L 29/04 LGP C09D 129/04 C09D 129/04

Claims (3)

[Claims] 1. An alkali metal acetate of 2% by weight or less,
Acetate of an alkali metal and a polyvinyl alcohol-based resin containing an acetoacetate group containing acetic acid as a main component at a ratio of acetic acid of 5% by weight or less and an alkali metal acetate / acetic acid weight ratio of 0.01 to 100. A paper processing agent characterized by: 2. An alkali metal acetate of 0.5% by weight or less, an acetic acid of 2% by weight or less, and an alkali metal acetate / acetic acid weight ratio of 0.1 to 10 are used. A paper-processing agent comprising, as a main component, an acetoacetic acid ester group-containing polyvinyl alcohol-based resin containing acetate and acetic acid. 3. The paper processing agent according to claim 1, which further comprises a crosslinking agent.