JPS6361440B2 - - Google Patents

Description

[Detailed description of the invention]

A. Industrial Application Field The present invention relates to an improved paper surface treatment method using a paper surface coating agent mainly composed of polyvinyl alcohol (hereinafter abbreviated as PVA) resin. An aqueous solution with a concentration of 0.1 to 10% by weight containing as the main component
(A) is applied, and then the concentration is 0.5 to 0.5 to 100%, which contains as a main component a copolymer of maleic anhydride and diisobutene in which more than 95 mol% of all carboxyl groups are basic salt units. This invention relates to a paper surface treatment method characterized by applying a 10% by weight aqueous solution (B). B. Prior Art Conventionally, PVA has been widely used as a surface coating agent for paper or paperboard. It's PVA
This is because it has excellent adhesion to paper and film-forming properties, and has particularly excellent film properties, so it has the function of improving paper surface properties such as paper surface strength, abrasion resistance, oil resistance, and printability. be. However, it is not possible to completely improve the performance of the paper surface.
When PVA-based aqueous solution is coated on the paper surface,
Due to the quality of the paper from which the paper is made, the permeability of the solution is high, so the performance cannot be sufficiently improved, and in particular, there is a drawback that the coefficient of surface friction is extremely reduced. This decrease in the surface friction coefficient is
This causes slipping during transportation after manufacture, which has a significant negative impact on work efficiency, safety, and product value. This sliding phenomenon was caused by the formation of a film.
It is thought that this occurs because PVA retains its plasticity while using water as a medium, smoothing the paper surface, and the degree of occurrence tends to increase as the temperature and humidity decrease. Furthermore, it has been confirmed that emulsions such as paraffin, calcium stearate, and polyethylene, which are used as adhesion prevention agents to rolls, have the effect of further promoting the slipping phenomenon. C. Problems to be Solved by the Invention As a measure to prevent this phenomenon, the applicant has previously found that a paper coating composition containing PVA as a main component in combination with an anti-slip agent is effective. A patent application was filed as Japanese Patent Application No. 52-83276. In other words, Japanese Patent Application No. 83276/1989 discloses a paper coating composition comprising a PVA resin and an aqueous solution containing a basic salt of a copolymer of one or more ethylenically unsaturated carboxylic acids and diisobutene. This invention is based on the premise that the treatment involves one-step coating on the surface of paper. However, as a result of repeated studies on paper surface treatment methods using this coating composition in order to further increase the anti-slip effect, we found that
An aqueous solution (A) containing PVA resin as a main component with a concentration of 0.1 to 10% by weight is applied, and then a copolymer of maleic anhydride and diisobutene with units exceeding 95 mol% of the total carboxyl groups is applied. By applying an aqueous solution (B) containing a basic salt copolymer as a main component with a concentration of 0.5 to 10% by weight, PVA
The present invention was completed based on the discovery that the intended purpose of preventing slipping on the paper surface could be more effectively achieved without impairing the physical properties such as adhesiveness, film-forming properties, and oil resistance inherent in the paper. It came to this. D Means for solving the problem In the paper surface treatment method of the present invention, the PVA resin applied to the paper surface as an aqueous solution (A) has a degree of polymerization in the range of 300 to 3000, particularly to improve the paper surface strength. A range of 1000 to 3000 is preferred for this purpose. The degree of saponification is determined when the water resistance of the paper is required.
It is preferably 95 mol% or more, but is not particularly limited to this range. As long as it does not impair the performance of PVA, such as water solubility, film forming properties, and adhesiveness,
PVA polymers in which part of the functional group is esterified or acetalized, or part of the polymer is crosslinked,
Alternatively, there is no problem in using a modified PVA polymer by copolymerization. In addition to the PVA resin, appropriate amounts of antifoaming agents, roll surface release agents, rust preventive agents, softeners, water resistance agents, gloss improvers, etc., which are usually used in conjunction with PVA, are added to the water-soluble (A). be able to. The concentration of the aqueous solution needs to be in the range of 0.1 to 10% by weight. The coating amount for practical use is usually in the range of 0.05 to 2 g/m ² . Next, a copolymer of maleic anhydride and diisobutene contained in the aqueous solution (B), in which more than 95 mol% of all carboxyl groups are basic salt units, will be described. Maleic anhydride and diisobutene are polymerized using a suitable solvent in the presence of a conventional radical initiator. It has been confirmed from the results of compositional analysis that the molar ratio of diisobutene and maleic anhydride in this copolymer is approximately 1:1. 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 dimethylformamide solution as a measure of the chain length of these copolymers, [η] = 0.05 to 1 dl/g, especially [η] = 0.05 to 0.3 dl. It is desirable to use a copolymer with a size of /g. In order to convert more than 95 mol% of the total carboxyl groups in the copolymer into basic salts, the carboxyl groups in the copolymer may be made basic in the presence of an alkaline substance. Alkaline substances used for this purpose include caustic alkali, alkali carbonate, ammonia or organic amines, more specifically sodium hydroxide, potassium hydroxide, sodium carbonate, lithium hydroxide, ammonium hydroxide, and ethanol. Examples include amines, but it is most practical to use sodium salts. A copolymer of maleic anhydride and diisobutene, in which more than 95 mol% of the total carboxyl groups are basic salts, can be used with polyacrylamide and sodium alginate for viscosity adjustment to improve coating suitability. , carboxymethyl cellulose (CMC), etc., or antifoaming agents, rust preventives, waterproofing agents, gloss finishing agents, etc. may be used in combination. The concentration of the aqueous solution is
It is used in practical use at 0.5 to 10% by weight, and the effective coating amount on the paper surface is preferably 0.01 g/m ² or more. Application of aqueous solution (A) and aqueous solution (B) to the paper surface is as follows:
Known methods such as calender size, size press, tab size, and roll coater are used. Note that the intended purpose can also be achieved by applying the aqueous solution (B) after the paper surface has once dried after applying the aqueous solution (A). E. Effects and Effects of the Invention According to the present invention, it is possible to treat various paper surfaces such as high-quality paper, paperboard, liner for corrugated board, white board, Manila board, etc., and the yield of the coating liquid on the paper surface layer is improved. This increases the water retention and flexibility of the paper itself,
The surface friction force is increased and the paper surface has an extremely excellent anti-slip effect. The present invention will be explained below with reference to examples (in the examples, % represents weight %). Example 1 In an autoclave under a nitrogen atmosphere, 105 g of diisobutene and 96 g of maleic anhydride were dissolved in 1500 ml of isopropyl acetate, and then a solution of 2.5 g of azobisisobutyronitrile dissolved in 100 ml of isopropyl acetate was sequentially added. The mixture was stirred for several minutes.
The autoclave was immersed in warm water at 80°C, and the reaction was carried out for 6 hours with stirring to obtain 195 g of white precipitate. This diisobutene/maleic anhydride copolymer (50 mol% of the latter, 30°C, DMF, intrinsic viscosity 0.16)
NaOH corresponding to a neutralization degree of 1.0 was added to the solution to form an aqueous solution. On the other hand, a 3% aqueous solution of volivinyl alcohol (hereinafter abbreviated as PVA) (degree of polymerization 1700, degree of saponification 99 mol%) was prepared, and this aqueous solution was mixed with nonionic surfactants, commercially available rust inhibitors (organic amines, fatty acid derivatives, cationic A mixture of surfactants, etc.) and a small amount of antifoaming agent were added to prepare the PVA composition liquid. Add the aqueous solution of the basic salt of the copolymer to this
Add and mix 1%, 5%, and 10% of the PVA solid content in terms of solid content to the PVA composition liquid, respectively.
A 3% aqueous solution containing PVA was prepared. These liquids were applied to corrugated liner paper using a size press at a liquid temperature of 60° C., a nip pressure of 20 kg/cm, and a speed of 100 m/min (liquid absorption amount: 18 g/m ² ) and dried. (Comparative Examples 3, 4, 5) In addition, 1% each of the basic salt of the copolymer,
5% and 10% aqueous solutions were prepared, and these solutions were applied to corrugated liner paper and dried in the same manner as described above. (Comparative Examples 6, 7, 8) On the other hand, after applying the 3% PVA-containing aqueous solution to a corrugated board liner, before the PVA aqueous solution dries, 0.5% of the basic salt of diisobutene/maleic anhydride copolymer, 1%, 5% and 8% aqueous solutions were subsequently applied (absorption amount: 11 g/m ² ) and dried. (Inventions 1, 2, 3, 4) Furthermore, after applying 0.5% and 1% aqueous solutions of basic salts of diisobutene/maleic anhydride copolymer to the corrugated liner, the 3% aqueous solution containing PVA was subsequently applied. , dried. (Comparative Examples 9 and 10) Furthermore, after applying the PVA-containing 3% aqueous solution to a corrugated board liner, diisobutene/
A 0.1% or 12% aqueous solution of a basic salt of maleic anhydride copolymer was successively applied and dried. (Comparative Examples 11 and 12) In addition, the anhydride ring of an equimolar copolymer of maleic anhydride and diisobutene (degree of polymerization 100) was 100% semi-esterified with isopropanol, and the acid group of the ring-opened anhydride ring was converted into ammonia. Coated paper was obtained by using a 1% aqueous solution of ammonium salt (X-1) either alone or as a second coating solution immediately after PVA coating (Control Examples 13 and 14). The surface slip angle was measured at a constant temperature of 20℃ and humidity of 45%. The results are shown in Table 1. Table 2 shows the results of measuring the physical properties of the paper at a temperature of 20°C and a constant humidity of 65%.

【table】

[Table] As shown in Table 1, it can be seen that the paper surface treated by the method of the present invention has an extremely superior anti-slip effect compared to the paper coated in one layer.

【table】

[Table] As shown in Tables 1 and 2, the coated paper obtained by the method of the present invention is significantly superior in sliding angle and water absorption compared to PVA alone;
It is superior in sliding angle compared to one-stage coating using PDIB/MAn and PDIB/MAn alone, and superior in sliding angle, taper wear, and printing gloss compared to PDIB/MAn alone. significantly superior in sliding angle, water absorption, and print gloss when compared to PDIB/MAn [i.e., anhydrous maleic The anhydride ring of an equimolar copolymer of acid and diisobutene (degree of polymerization 100) is 100% semi-esterified with isopropanol, and the acid group of the ring-opened anhydride ring is converted into an ammonium salt with ammonia (X −
1) Compared to single or two-stage application, the sliding angle is
It can be seen that it is significantly superior in water absorption, taper abrasion, and printing gloss.

Claims (1)

[Claims] 1 The paper surface is an aqueous solution (A) with a concentration of 0.1 to 10% by weight containing polyvinyl alcohol-based resin as the main component and a copolymer of maleic anhydride and diisobutene, and units exceeding 95 mol% of the total carboxyl groups. When surface treatment is performed using an aqueous solution (B) with a concentration of 0.5 to 10% by weight containing a copolymer whose main component is a basic salt as a coating composition, the above aqueous solution (A) with a concentration of 0.1 to 10% by weight is used as a coating composition. A method for surface treatment of paper, which comprises applying an aqueous solution (B) having a concentration of 0.5 to 10% by weight.