JPS6223116B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a paper processing agent that prevents staining caused by adhesion of modified polyvinyl alcohol to dryer rolls and calender rolls when the modified polyvinyl alcohol is used for the purpose of paper processing. Improve paper size, paper surface strength,
In order to improve oil resistance, smoothness, etc., it is known to treat paper with an aqueous polyvinyl alcohol solution by means such as impregnation or coating. However, when the paper subjected to such treatment is dried by passing it between rolls in the next step, there is a problem that the dryer roll, canvas roll, and calender roll gradually become dirty, and the dirt gradually accumulates. In the present applicant, the Z-axis strength of paper, surface strength,
We are conducting research and development on a method of treating paper with modified polyvinyl alcohol that has been copolymerized and modified with an unsaturated acid in order to further improve the Betssel Pick. There is a problem that the dryer roll, canvas, and calender roll become more dirty than usual. This type of dirt damages the surface properties of the paper and deteriorates its quality, so the roll surface must be cleaned from time to time. However, in high-speed machines, stopping the machine from time to time to clean the roll surface can be fatal to productivity. There is no denying that it is a disadvantage. However, in order to deal with this problem, methods have been proposed in which additives such as polyhydric alcohol, paraffin emulsion, anionic surfactant, nonionic surfactant, urea, etc. are added to the polyvinyl alcohol aqueous solution, but the effect is Not necessarily enough. Moreover, these methods may, in some cases, increase the foaming properties of the polyvinyl alcohol aqueous solution, make the polyvinyl alcohol coated paper repellent to water, make the paper slippery, or reduce the mechanical and chemical stability of the coating solution. It may be accompanied by drawbacks such as poor printability and decreased printability. However, the present inventors have carried out extensive research in order to solve the above conventional problems, and as a result, a vinyl ester-unsaturated dicarboxylic acid monoester copolymer was added to an aqueous solution containing unsaturated acid-modified polyvinyl alcohol as the main ingredient. When coexisting, even if paper treated with the aqueous solution is fed between the rolls,
It is said that stains do not occur on the roll surface for long periods of time, and that the inherent properties of the unsaturated acid-modified polyvinyl alcohol paper treatment agent, such as sizeability, printability, and Z-axis strength, are not impaired or even tend to be improved. After discovering this fact, we have completed the present invention. The paper treatment agent of the present invention consists of 100 parts by weight of unsaturated acid-modified polyvinyl alcohol and 0.1 to 30 parts by weight of vinyl ester-unsaturated dicarboxylic acid monoester copolymer. Unsaturated acid-modified polyvinyl alcohol refers to a saponified copolymer of a vinyl ester such as vinyl acetate and a comonomer such as those exemplified below. (a) Unsaturated monocarboxylic acids such as acrylic acid, methacrylic acid, and crotonic acid or their salts. (a) Unsaturated polycarboxylic acids such as maleic acid, fumaric acid, and itaconic acid, or their salts, partial esters, and anhydrides. (c) Unsaturated sulfonic acids or salts thereof, such as ethylene sulfonic acid, allyl sulfonic acid, and meta-allylsulfonic acid. (d) Unsaturated acid amides such as acrylamide and methacrylamide, provided that at least a part of them is exchanged into the form of the unsaturated acid or its salt during the saponification reaction. The appropriate copolymerization ratio of these comonomers is 0.5 to 30 mol%, especially 1 to 20 mol%. The improvement effect cannot be fully exhibited, and if the proportion is too high, the water resistance of the paper will decrease and the surface strength will also deteriorate. It should be noted that there is no particular problem in having a third component as a copolymerization component in addition to the unsaturated acid component to the extent that it does not impair the spirit of the present invention. The degree of saponification of the copolymer of vinyl ester and the above-mentioned comonomers is selected from the range of about 40 to 100 mol%, especially 70 mol% or more. If the degree of saponification is too low, the sizing and paper strength enhancement effects are There will be a shortage. Next, examples of the vinyl ester in the vinyl ester-unsaturated dicarboxylic acid monoester copolymer include vinyl acetate, vinyl propionate, vinyl stearate, vinyl benzoate, and saturated branched fatty acid vinyl. It is common to use it, or at least to use it primarily. Examples of the unsaturated dicarboxylic acid monoester component include monoesters of unsaturated dicarboxylic acids such as maleic acid, methylmaleic acid, fumaric acid, methylfumaric acid, itaconic acid, and glutaconic acid. The number of carbon atoms in the alkyl group of the ester group is, for example, 1 to 20, but especially 4.
-18 has a large roll adhesion prevention effect. The copolymer may further contain a small amount of an unsaturated acid or a salt thereof as a third component. The above copolymer is obtained by copolymerizing a vinyl ester and an unsaturated dicarboxylic acid monoester according to a conventional polymerization method. It can also be obtained by copolymerizing vinyl ester and maleic anhydride in alcohol. During polymerization, the degree of polymerization of the copolymer can be greatly varied by appropriately selecting the ratio of solvent and monomer, coexisting a chain transfer agent, and appropriately selecting the type and amount of polymerization catalyst. It may be lowered to That is, the copolymers used in the present invention include not only polymers but also oligomers. A lower degree of polymerization can also be achieved by cleaving the main chain of the polymer with a peroxide or the like. The proportions of the vinyl ester component and the unsaturated dicarboxylic acid monoester component in the above copolymer can vary widely, but usually the vinyl ester component accounts for approximately 50% to 90%, and the unsaturated dicarboxylic acid monoester component accounts for the remainder. There are many things to do. Note that the acid group in the unsaturated dicarboxylic acid monoester component in the above copolymer may lack water solubility or water dispersibility in the form of a free acid, so in such cases, hydroxide, ammonia, basic inorganic At least a portion of the acid groups may be neutralized with a basic substance such as a salt or amines. Even if the aqueous solution or aqueous dispersion of the above-mentioned copolymer is cloudy, its action will not be adversely affected. The combined ratio of vinyl ester-unsaturated dicarboxylic acid monoester copolymer to unsaturated acid-modified polyvinyl alcohol should be 0.1 to 30 parts by weight per 100 parts by weight of the former;
If it is less than 0.1 part by weight, the modifying effect will be insufficient, while if it exceeds 30 parts by weight, it will have the disadvantage of lowering the strength of the paper. The unsaturated acid-modified polyvinyl alcohol and the vinyl ester-unsaturated dicarboxylic acid monoester copolymer can be mixed by adding the latter to the powder of the former in advance, or by mixing both in the form of an aqueous solution or an aqueous dispersion. Any method can be employed, such as adding the latter to an aqueous solution of the former or vice versa. Paper is treated with an aqueous solution containing unsaturated acid-modified polyvinyl alcohol and a vinyl ester-unsaturated dicarboxylic acid monoester copolymer (however, the latter may be dispersed in water); Although the concentration of saturated acid-modified polyvinyl alcohol is not particularly limited, it is practical to set it to about 0.1 to 10% by weight. Note that there is no particular problem in using other polymer components together with modified polyvinyl alcohol, and other additives such as latex, fillers, pigments, dyes, waterproofing agents,
Rust inhibitors, antifoaming agents, surfactants, plasticizers, organic solvents, thixotropic agents, and the like may be added as appropriate. Examples of the treatment include size press coating and surface coating using a calender roll. Next, the paper processing agent of the present invention will be further explained by giving an example. In the following, "%" is expressed on a weight basis unless otherwise specified. Example 1 Vinyl acetate and monooctyl maleate were copolymerized in isopropanol under the following conditions, the reaction product was poured into water to precipitate, and after separation and drying, it was poured into an aqueous ammonia solution and dissolved. Monomer charge weight ratio Vinyl acetate: Monooctyl maleate = 83:
218 Solvent/monomer weight ratio 0.5 Polymerization catalyst and amount used Benzoyl peroxide 1.0% (based on monomer) Chain transfer agent and amount used n-lauryl mercaptan 0.026% (based on monomer) Polymerization temperature 75-85℃ Polymerization time 10 hours Copolymer composition (mole ratio) Vinyl acetate: Monooctyl maleate = 50:50 Neutralizing agent PH and viscosity of 15% aqueous solution of copolymer after neutralization with ammonia PH7.2, 10.6cps (20℃) Above 99.0% of the vinyl acetate component of a monomethyl maleate-vinyl acetate copolymer with a monomethyl maleate content of 3.0 mol% was added to the aqueous solution of the obtained copolymer.
Add denatured polyvinyl alcohol powder with a degree of polymerization of 1700 and saponify mol %, add water, and heat and stir to make 4% of denatured polyvinyl alcohol.
An aqueous solution was prepared. The ratio of the modified polyvinyl alcohol and the copolymer in the aqueous solution was such that the copolymer was 10% to the modified polyvinyl alcohol. Soak a 4cm x 11cm dry cloth in this aqueous solution,
It was attached to an iron roll heated to 90°C, dried for 10 minutes, and then peeled off at a speed of 2 m/min. The average value of peel resistance measured over 10 times was 65 g/cm, and there was almost no stain on the roll surface at the peeled area. Next, using a Dixon coater, the above aqueous solution was coated on the surface of a corrugated board liner with an outer diameter of 10 cm at a wet weight of 10 g/ ^m2 using a bar coating method.
The sample was continuously brought into contact with an iron heating roll (temperature 110°C) at a speed of 3 m/min. As shown in Table 1, almost no staining of the roll was observed even after 6 hours of continuous operation. Example 2 According to Example 1, an ammonia-neutralized product of vinyl acetate-monobutyl maleate copolymer (molar ratio 50:50) was obtained. The pH and viscosity of a 15% aqueous solution of the copolymer after neutralization were PH7.1 and 2.1 cps (20°C). By mixing the modified polyvinyl alcohol used in Example 1 with the aqueous solution of this copolymer, a 4% aqueous solution of modified polyvinyl alcohol was prepared. The ratio of copolymer to modified polyvinyl alcohol is
It was set to 10%. When a dry cloth is dipped in this aqueous solution and attached to an iron roll heated to 90℃, the peel resistance is 100.
g/cm, and there was hardly any stain on the roll surface at the peeled area. Also, when paper was passed through a heated roll using this aqueous solution, almost no staining of the roll was observed as shown in Table 1. Control example 1 4% of the modified polyvinyl alcohol used in Example 1
The results of the iron roll peel test using only the aqueous solution and the heated roll paper passing test were extremely unsatisfactory as shown in Table 1. Control Examples 2-4 4% of modified polyvinyl alcohol used in Example 1
1% to modified polyvinyl alcohol in aqueous solution
10% glycerin (Control example 4) was added to the amount of polyoxyethylene lauryl ether (Control example 2), polyoxyethylene nonyl phenol ether (Control example 3), and modified polyvinyl alcohol, followed by iron roll peeling test and heating. Roll paper passing was carried out, but as shown in Table 1, satisfactory results were not necessarily obtained.

[Table] Examples 3 to 6 Tests similar to those in Example 1 were conducted using the following copolymers. The contents of the copolymer are shown in Table 2, and the test results are shown in Table 3.

【table】

【table】

[Table] Examples 7 to 11 The same method as in Example 1 was carried out using the following combinations of polyvinyl alcohol resin and copolymer. The test results are shown in Table 4. Example 7 4% aqueous solution of modified polyvinyl alcohol with a degree of polymerization of 1700 obtained by saponifying 98.0 mol% of the vinyl acetate component of an acrylic acid-vinyl acetate copolymer with an acrylic acid content of 5.0 mol% Neutralization of the copolymer used in Example 2 Example 8 Modified polyvinyl with a degree of polymerization of 1400 obtained by saponifying 99.0 mol% of the vinyl acetate component of a crotonic acid-vinyl acetate copolymer with a crotonic acid content of 3.0 mol%. 4% aqueous solution of alcohol Neutralized copolymer used in Example 5 (5% used in crotonic acid-modified polyvinyl alcohol) Example 9 Methacrylic acid with methacrylic acid content of 3.0 mol%
A 4% aqueous solution of methacrylic acid-modified polyvinyl alcohol with a degree of polymerization of 1400 obtained by saponifying 99.0 mol% of the vinyl acetate component of the vinyl acetate copolymer. Example 10 Polymerization degree obtained by saponifying 99.0 mol% of the vinyl acetate component of a vinyl sulfonate sodium-vinyl acetate polymer with a sodium vinyl sulfonate content of 2.0 mol%
4% aqueous solution of polyvinyl alcohol modified with sodium allylsulfonate of 1700 Neutralized copolymer used in Example 1 (5% used in polyvinyl alcohol modified with sodium vinylsulfonate) Example 11 Allyl with sodium allylsulfonate content of 0.5 mol% Degree of polymerization obtained by saponifying 99.0 mol% of the vinyl acetate component of sodium sulfonate-vinyl acetate copolymer
4% aqueous solution of polyvinyl alcohol modified with sodium allylsulfonate of 800 Neutralized copolymer used in Example 1 (5% used in polyvinyl alcohol modified with sodium allylsulfonate) Control Examples 5 to 9 Used in Examples 7 to 11 The same test as in Example 1 was conducted, except that each 4% aqueous solution of modified polyvinyl alcohol (referred to as Control Examples 5 to 9) was used alone. The test results are shown in Table 4.

【table】

Claims (1)

[Scope of Claims] 1. A paper treatment agent comprising 100 parts by weight of unsaturated acid-modified polyvinyl alcohol and 0.1 to 30 parts by weight of vinyl ester-unsaturated dicarboxylic acid monoester copolymer. 2. The paper treating agent according to claim 1, wherein at least some of the ester groups in the unsaturated dicarboxylic acid monoester component are alkyl esters having 4 or more carbon atoms. 3. The paper processing agent according to claim 1, wherein the amount of modification of the unsaturated acid-modified polyvinyl alcohol is 1 to 20 mol%.