JPH06287891A - Production of paper and paper board - Google Patents

Abstract

PURPOSE:To provide a coating process for improving the surface strength and blocking resistance of paper and paper board. CONSTITUTION:Paper or paper board is produced by using a surface-coating agent produced by adding caustic soda in the process to dissolve a polyvinyl alcohol having a saponification degree of 90-99mol% under heating, thereby raising the saponification degree to 100mol%.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The invention of the present application relates to a method for producing paper and paperboard, which is coated with 100 mol% saponified polyvinyl alcohol for improving the surface strength and blocking property of the paper. It is characterized by using as.

[0002]

2. Description of the Related Art In the case of printing on paper and paperboard products, problems caused by stains on the blanket cylinder of a printing machine, that is, the printing workability and operability are greatly reduced, and the deterioration of the printed matter is significantly reduced, resulting in a marked decrease in commercial value. There is something to do. In many cases, the blanket cylinder is soiled by the paper itself, which is caused by the run-out on the paper surface and the foreign substances attached to the paper surface. Trays on the paper surface often come from the surface strength such as peeling and peeling.On uncoated paper, it is due to short fibers and dust adhering to the surface, and on coated paper its surface coating. It may be due to the labor cost. Cutters as foreign matter adhering to the paper surface, those caused by paper powder and short fibers that are simply generated during slitter processing, those caused by transfer from the back surface to the front surface due to blocking with the back surface of the paper, One of the causes of stains is that the binder, filler, chemicals, etc. added before papermaking migrate to the paper surface during migration through each step of papermaking.

Conventionally, in the manufacture of paper, various surface treatment agents have been used in order to improve printability and surface strength, and many studies have been made on the improvement of treatment agents and application methods. Generally, various starches, urea, melamine-formaldehyde resin, synthetic rubber latices, polyvinyl alcohol, polyacrylamide, etc. are used as the type of treating agent. Among them, starch and polyvinyl alcohol are widely used. It is used extensively.

As a prior art relating to polyvinyl alcohol, which has a technical problem different from that of the present invention, unsaturated monocarboxylic acid (acrylic acid, methacrylic acid, acrylic acid, methacrylic acid, etc.) is used to improve the blister resistance of rotary offset printing paper. Of crotonic acid and salts thereof) and vinyl acetate, a modified polyvinyl alcohol saponified by 97 mol% or more of the vinyl acetate component is size-pressed,
Technology used for calendar size (Japanese Patent Publication No. 60-39)
No. 799), of which, although the vinyl acetate component is saponified to a high value, the residual unsaturated monocarboxylic acid component is contained in a considerable amount in a salt form, and the problems with the components of the present invention And the configuration is different and is not a comparison target. The present invention cannot be achieved as long as 1% or more of acetic acid groups or other groups are present in the polyvinyl alcohol component.

[0005]

As a problem of polyvinyl alcohol for surface treatment of paper which has been generally used conventionally, the surface strength of the coated surface is insufficient, either polyvinyl alcohol coated surface or polyvinyl alcohol coated surface and filler. The problem of blocking property with the coated surface is that the contamination of the after-roll in the coating process cannot be avoided. Heretofore, as an attempt to improve that point, methods such as increasing the saponification degree of polyvinyl alcohol, increasing the polymerization degree of polyvinyl alcohol, and adding an anti-blocking agent and a dusting inhibitor have been adopted.

Among them, the method of increasing the degree of saponification of polyvinyl alcohol is known to reduce the tackiness of the film and to improve the appropriate drying property and paper strength. Even the so-called completely saponified product has a saponification degree of 97 to 99 mol%, does not exhibit the intended action and effect, and has not yet completely solved the above-mentioned drawbacks. Also,
The method of increasing the degree of polymerization is difficult to handle because it increases the viscosity of polyvinyl alcohol, and the method of adding other chemicals has the drawback that the surface strength is reduced and the original properties of polyvinyl alcohol are diminished.

Conventionally, polyvinyl alcohol used for coating the surface of paper has a saponification degree of 97 to 99 mol% even though it is usually called a complete saponification product, and it is melted by heating to be used for coating. The coating with polyvinyl alcohol having a saponification degree of 100 mol% was not considered for paper coating because of its solubility and cost. As a result of intensive research beyond the practice of this invention, 1
Surprisingly, we have found that 00 mol% saponification can greatly improve the surface strength and blocking resistance of coated paper, and at the same time, it can be applied to paper at a low cost and easily in handling. I was able to make a big contribution.

[0008]

In the present invention, generally, a completely saponified polyvinyl alcohol having a saponification degree of 90 to 99 mol%, preferably 98 to 99 mol% is used as a starting material, and the starting material is dissolved by heating. Succeedingly, caustic soda was added at the time of making, and it succeeded in making the thing of 100 mol% of saponification degree. The amount of caustic soda used at that time is sufficiently equimolar to the unsaponified acetic acid groups remaining in the polyvinyl alcohol, and there is no problem even if the amount is slightly large. 1
There are various methods for identifying 00 mol% saponified polyvinyl alcohol. The polyvinyl alcohol is dissolved under a reaction temperature of 90 to 98 ° C., preferably 95 ° C. or higher, and a reaction time of 30 minutes to 90 minutes, preferably 60 minutes or longer. The polyvinyl alcohol produced in this way has a reduced film tackiness and excellent drying property,
The coated paper has remarkably improved surface strength and has an unexpected and remarkable effect. There is no particular limitation on the method of coating the polyvinyl alcohol on the paper surface, machine calender and roll, air knife, on-machine coater such as blade coater,
Not limited to off-machine coaters, it can be used without any problems.

[0009]

By applying the polyvinyl alcohol prepared by the above-mentioned method to the paper, the adhesiveness of the coated surface of the paper is reduced and the surface strength is also increased. The polyvinyl alcohol used in this invention is 100 mol% saponified,
There is no acetate group in the molecule, and the main chain is a repeating 1,3-glycol unit, which is considered to be a 1,3-glycol type. This fully saponified product increases hydrogen bonds between the hydroxyl groups and in the molecules to increase water resistance and paper peeling resistance to improve the blocking property and prevent contamination of the blanket cylinder of the printing machine.

[0010]

Example 1 100 g of polyvinyl alcohol having a saponification degree of 99, 0 mol% and a degree of polymerization of 1800, which is a raw material, was dispersed in 1000 cc of cold water in a beaker, and an equimolar amount (0.900 g of solid: 0.900 g of solids) was left in the dispersion. ) Of caustic soda was added, and the temperature was raised by heating and the temperature was kept at 95 ° C., and the mixture was dissolved over 1 hour. This solution was applied onto a polyethylene film to prepare a polyvinyl alcohol film. This film was placed into a coating paper and Hinuri Engineering on paper, is crimped over the top the load ^{5Kg / cm 2/50 ℃ /} 3 minutes. The peeling condition of the boundary between the polyvinyl alcohol film and the paper surface and the strength were measured by a tensile tester. Separately, the polyvinyl alcohol solution was placed in a petri dish and dried in a drier, and the drying property was measured by the time until the water content became zero. Further, a polyvinyl alcohol solution was coated on the surface of the paper, and the surface strength was measured by an RI printing tester. (Table 1)

[0011]

Example 2 100 g of polyvinyl alcohol having a saponification degree of 98.5 mol% and a polymerization degree of 2500 as a raw material was dispersed in 1000 cc of cold water in a beaker and equimolar to the residual acetic acid group (solid 0.905 g). Caustic soda was added and dissolved in the same manner as in Example 1. This solution was applied onto a polyethylene film to prepare a polyvinyl alcohol film. The peeling condition, strength, drying property, and surface strength of this film were measured by the test method of Example 1. (Table 1)

[0012]

Comparative Example 1 The same procedure as in Example 1 was carried out except that caustic soda was not added when dissolving polyvinyl alcohol. (Table 1)

Comparative Example 2 Similarly, the procedure of Example 2 was repeated except that caustic soda was not added when the polyvinyl alcohol was dissolved. (Table 1)

[Table 1]

[0013]

INDUSTRIAL APPLICABILITY As described above, an unexpected effect, which has not been obtained even with a highly saponified product which has been conventionally called a completely saponified polyvinyl alcohol, has an unsaponifiable residual acetic acid group when heated and dissolved. The fact that attention was paid to the addition of caustic soda in an equimolar amount or a slight excess was a factor in obtaining a 100 mol% saponified product. The polyvinyl alcohol thus obtained should sufficiently improve the tackiness and dryness of the film. I was able to. Therefore, by coating on the surface of paper and paperboard, the blocking resistance of paper is improved, and since the bond between pulp fibers on the paper surface is good, the surface strength is improved and various papers in a series of paper manufacturing processes are improved. It is significant that the problem was solved in a hurry. In other words, after roll stains in the coating process and stains on the blanket cylinder of the printing machine in the printing process were drastically reduced, and it was possible to greatly improve the operability, so the impact on the productivity of paper and paperboard is large. is there.

Claims (2)

[Claims] 1. A method for producing paper or paperboard, which comprises making paper stock solution containing pulp and various chemicals, and then applying a surface treatment agent to one or both sides of the papermaking material. A method characterized by applying a solution of alcohol dissolved in caustic soda to the surface of a paper. 2. The method for producing paper and paperboard according to claim 1, wherein the polyvinyl alcohol solution is polyvinyl alcohol saponified at 100 mol% when dissolved.