JPS5932595B2 - Coating composition for paper - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a coating composition for paper containing a polyvinyl alcohol resin (hereinafter polyvinyl alcohol is abbreviated as PVA) as a main component.

More specifically, it is a copolymer of polyvinyl alcohol resin A and one or more compounds selected from the group consisting of a small proportion of diisobutene and monobasic or dibasic vinylcarboxylic acids based on component A. 10 Coating composition for paper containing basicity. Conventionally,
PVA is widely used as a surface coating for paper or paperboard.

This is because PVA has excellent adhesion to paper and film-forming properties, and exhibits especially excellent film properties, so it has the function of improving various properties such as paper surface strength, abrasion resistance, oil resistance, etc. be. However, when applying a PVA aqueous solution to paper using a size press or a calender roll, the dryer roll and calender roll are
In addition to causing stickiness and gum-up, which seriously stains the rolls, the product is also contaminated by paper peeling and paper powder scattering, which poses a serious operational problem.

For this reason, PVA is usually mixed with paraffin emulsion, calcium stearate, polyethylene or other emulsions, and other release agents for practical use. Generally, when a PVA aqueous solution is coated on a paper surface, there is a drawback that the friction coefficient of the paper surface is extremely reduced.

As a result, slipping occurs during transport after being made into a box,30 which has a severe negative impact on safety, work efficiency, and product value. This sliding phenomenon is thought to occur because the formed PVA film uses water as a medium and maintains a circular shape, making the paper surface smooth.
The degree of occurrence tends to increase as the temperature and humidity decrease. Furthermore, it has been confirmed that the above-mentioned Roughin, calcium stearate, and the like, which are used as adhesion prevention agents to rolls, have the effect of further promoting the slipping phenomenon. As a measure to prevent this phenomenon, the present applicant previously discovered that a paper coating composition containing PVA as a main component in combination with silicon dioxide was effective, and filed a patent application as Japanese Patent Application No. 51-116864. I did this. However, even when a coating composition made of such a system is used, the anti-slip effect is not significant. Furthermore, if an inorganic substance that is not soluble in water, such as silicon dioxide, is present in the coating composition, it is undesirable because it will cause adhesion to the coating or staining during the coating process. In view of the above circumstances, the present inventors conducted studies to improve the slipperiness of the paper surface and found that polyvinyl alcohol resin A and a small proportion of diisobutene and monobasic or diisobutene were added to the polyvinyl alcohol resin A and the component A. A paper coating composition consisting of an aqueous solution containing a base bent salt of a copolymer with one or more compounds selected from the group consisting of vinylcarboxylic acids in the base group is effective in preventing such slipping phenomenon. Not only is there
The present invention was completed based on the discovery that PVA is effective in coating paper surfaces without impairing its inherent properties such as adhesive notes, film-forming walls, and oil-proofing. In the paper coating composition of the present invention, the PVA resin blended as the main component has a polymerization degree of 300 to 3.
000 range, especially 1 for the purpose of improving paper surface strength.
A value in the range of 000 to 3000 is preferred.

The degree of saponification is 95 mol if paper-like water resistance is required?
The above values are preferred, but the range is not particularly limited. Aqueous solution, film forming, adhesive bending, etc. PVAO) PVA-based polymers with some of the functional groups esterified or acetalized, or some cross-linked polymers, as long as they do not impair the bending ability. Weird F due to polymerization! 4. There is nothing wrong with using a PVA-based polymer. In addition, the vinyl carboxylic acid having a single base group used for copolymerization with diisobutene as one component constituting the copolymer is acrylic acid,
methacrylic acid, crotonic acid, cinnamic acid, etc. In addition to acrylamide and acrylonitrile, various aryl esters of vinyl carboxylic acids such as acrylic acid, methacrylic acid, crotonic acid, and cinnamic acid (depending on the number of carbon atoms in the aryl group) is 1~
9) and other compounds having a functional group that can be converted into a carboxyl group are also included. Vinyl carboxylic acids, also referred to as dibasic notes, refer to maleic acid, fumaric acid, itaconic acid, citraconic acid, etc.
It also includes compounds having a functional group that can be converted into a carboxyl group, such as citraconic acid anhydride or its mono- and dialyl esters (the carbon number of the carbonyl group is 1 to 9). These monobasic or dibasic vinylcarboxylic acids and diisobutene are polymerized using a suitable solvent in the presence of a conventional radical initiator. Among these, the most preferable base salt for the copolymer to be blended into the PVA-based resin is one based on a copolymer of diisobutene and maleic anhydride. It has been confirmed that the molar ratio of diisobutene to maleic anhydride is approximately 1:1. However, when a vinyl carboxylic acid other than maleic anhydride is used, the copolymerization ratio with diisobutene is not necessarily this ratio. Further, if necessary, a small amount of monomers such as styrene and methyl vinyl ether can be copolymerized during the polymerization. Using the intrinsic viscosity [η] measured at 30°C in a dimethylform γ amide solution as a measure of the chain length of these copolymers, [η] = 0.05 to 1, especially [η] = 0. 05～
Preferably, a copolymer with a size of 0.3 is used. In order to use the above copolymer as a base salt, the carboxyl group in the copolymer may be modified with a base in the presence of an alkaline substance.

Alkali substances used for this purpose include gamma alkali, alkali carbonate, ammonia, or organic amines, and more specifically, sodium hydroxide, potassium hydroxide, sodium carbonate, lithium hydroxide, hydroxide, etc. Examples include ammonium, ethanolamine, etc.
It is most practical to use the sodium salt. PVAlOO weight in paper coating composition? The blending ratio of the base salt in the copolymer is 0.5 to 10% by weight.
is suitable.

To prepare the coating composition, 1) PVA powder, the copolymer before being made into a base salt, and an alkaline substance are simultaneously dissolved in water, 2) An aqueous solution containing the base group salt of the copolymer is added to the PVA aqueous solution, 3) PVA A possible method is to mix a powdered base salt of a copolymer with a powder and dissolve the mixture in water. The coating composition for paper has an aqueous solution concentration of 0.1 to 20% by weight? It is put into practical use. Coating on the paper surface can be applied to various types of paper such as high-quality paper, paperboard, corrugated pole liner, white pole, Manila board, etc. using known methods such as Yarnender Size, Size Press, Tab Size, and S)S Rule Coater. It is.

By using the paper coating composition of the present invention, paper that has been surface-treated with a coating composition containing a conventional PVA aqueous solution as a main component can be cured by the adhesion of the paper fibers "Kepa", thereby reducing the recesses between the paper fibers. It is clearly recognized that while increasing the buried and smooth wall makes it easier to slip, increasing the moderate water retention wall and flexible wall increases the surface friction force and significantly reduces the sliding wall.

Furthermore, there was a tendency for the water absorption envelope of paper to become smaller. This means that the hydrophobicization of the paper surface has been promoted, and conventional paper coating compositions containing PVA resin as a main component do not have such effects. Note that there is no problem in adding appropriate amounts of conventionally known roll release agents, rust preventives, antifoaming agents, softeners, waterproofing agents, gloss improvers, etc. to the coating composition of the present invention.

The present invention will be explained below with reference to Examples.

Example 1 Isopropyl acetate 3 in an autoclave under nitrogen atmosphere
After 000ml diisobutene 9009 and azobisisobutyronitrile 8.59 were sequentially dissolved under pressure, the temperature was 60°C.
It was kept at ℃.

On the other hand, isopropyl acetate solution of acrylic acid (25% by weight)
was continuously charged into the polymerization system for 8 hours using a delay method at a flow rate of 309/Hr (:) I). After the preparation was completed, the reaction was continued. The reaction was precipitated with methanol and the polymer was isolated. The yield of the copolymer after drying was 639.
This copolymer of diisobutene and γ-acrylic acid (acrylic acid content: about 40 moles, 30 copolymer, intrinsic viscosity in CDMF of 0.
24) is dissolved to a concentration of 10% using sodium carbonate in the same molar amount as the carboxyl group in the copolymer. Separately, a PVAlO% aqueous solution with a degree of polymerization of 1700 and a degree of saponification of 99 mol% is prepared. Then, the copolymer was mixed at a ratio of 1 part, 5 parts, and 10 parts (in terms of solid content) to PVAlOO part (in terms of solid content) to prepare a 3% aqueous solution. This aqueous solution was applied to the surface of corrugated liner paper (0.39/m") and the surface stiffness angle was measured. As shown in Table 1, the addition of the copolymer significantly reduced the stiffness. It is clear that the angle becomes larger, that is, the slippage is improved.Example 2 Diisobutene 105 in an autoclave under a nitrogen atmosphere
9. Next, a solution of maleic anhydride 969 dissolved in 1500 ml of isopropyl acetate and a solution of azobi-tau-sisobutyronitrile 2,59 dissolved in 100 ml of isopropyl acetate were sequentially added, and the mixture was stirred for about 10 minutes. .

Immerse the autoclave in 70℃ warm water for 6 hours under stirring.
The reaction was carried out and a white precipitate was obtained. This copolymer of diisobutene and 9-maleic anhydride (maleic anhydride content 50 mol?, intrinsic viscosity 0.15 in DMF at 30°C) was made into a 10% aqueous solution with NaOH corresponding to a neutralization degree of 1.0. did. Separately, degree of polymerization: 17001, degree of saponification: 98.9 mol%
of the copolymer (solid 5 minute equivalent) 1 for PVAlOO part of
1, 5 parts, and 10 parts, and heated and dissolved at 90° C. for 30 minutes to prepare an aqueous solution with a concentration of 3%. This aqueous solution was applied to the surface of a corrugated pole liner paper at a rate of 0.39/Rr, and the paper surface roughness angle and water absorption were measured. The results are shown in Table 2. From Table 2, it was found that the paper surface slippage l can be greatly improved and the water absorption (Kopp method) is extremely small.

Example 3 Diisobutene 5.99, maleic anhydride 4.99, ethyl acetate 80r11 et-butanol 30W11 azo SS
0.139 of bisisobutyronitrile was heated in an autoclave at 55° C. for 5 hours to obtain 10.19 of a copolymer of diisobutene and maleic anhydride.

This copolymer (intrinsic viscosity 0.3 in DMF at 30° C.) was made into an aqueous solution by adding NaOH corresponding to a degree of neutralization of 1.0. As in Example 2, when an aqueous solution of composition Z mixed with PVA was applied and the sliding curve of the paper surface was compared, it was found that those with a high degree of polymerization (high intrinsic viscosity) had a slightly lower mass angle. Ta. Example 4 The coated paper envelopes of the copolymers prepared in Examples 1 to 3 were tested in comparison with conventional products.

The three types of copolymers were dissolved in NaOH with a degree of neutralization of 1.0,
Polymerization degree 1700, saponification degree 99% PVA with 5 parts per 100 parts (in terms of solid content) was added, and as an additive, 0.7 parts of nonionic surfactant (polymer diethylene nonylphenol ether), commercially available. 4 parts of rust inhibitor (mixture of organic γ-mine, fatty acid derivative, cationic surfactant, etc.),
0.2 part of a commercially available antifoaming agent was blended to prepare a 3% aqueous solution containing PVA by calorothermal dissolution. As a control, 30% paraffin emulsion was added to the commonly used PVAlOO part.
A comparison test was conducted between a 3% PVA-containing solution to which 50 parts of a liquid was added and a solution to which 30 parts of a 20% dispersion of colloidal silica was separately added.

It was coated (0.359/d) on a corrugated liner paper and dried on a sander roll at a temperature of 70°C.

Claims (1)

[Scope of Claims] 1. Polyvinyl alcohol resin A and one or more compounds selected from the group consisting of diisobutene and monobasic or dibasic vinyl carboxylic acid in a small proportion relative to component A. A coating composition for paper containing a basic salt B of a copolymer. 2. The paper coating composition according to claim 1, wherein component B is a basic salt of a copolymer of diisobutene and maleic anhydride. 3 Component B is 30% in dimethylformamide solution
The paper coating composition according to claim 1, which has an intrinsic viscosity [η] of 0.05 to 1 as measured at °C.