JPS6223114B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a paper processing agent that prevents staining caused by adhesion of polyvinyl alcohol resin to dryer rolls and calender rolls when 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. Polyvinyl alcohol accumulates this stain more than other paper treating agents. This dirt damages the surface properties of the paper and degrades the quality of the paper, 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 is so disadvantageous as to be fatal to productivity. Some things are beyond dispute. 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,
Disadvantages such as increasing the foaming properties of polyvinyl alcohol aqueous solutions, making polyvinyl alcohol coated paper repellent to water, making the paper more slippery, poor mechanical and chemical stability of the coating liquid, and decreasing printability. may be accompanied by However, the present inventors have carried out extensive research in order to solve the above-mentioned conventional problems, and as a result, a vinyl ester-unsaturated dicarboxylic acid monoester copolymer (B) is added to an aqueous solution containing polyvinyl alcohol (A) as a main ingredient. ), even if paper treated with the aqueous solution is fed between the rolls, stains will not occur on the roll surface for a long time, and the inherent size properties of the polyvinyl alcohol paper treatment agent
The present invention was completed based on the discovery that properties such as printability are not impaired in any way, but rather tend to be improved. The paper treatment agent of the present invention contains polyvinyl alcohol (A)
100 parts by weight and 0.1 to 30 parts by weight of the vinyl ester-unsaturated dicarboxylic acid monoester copolymer (B). As polyvinyl alcohol (A) in the present invention, polyvinyl alcohol with a degree of polymerization of 300 to 3000 is used, but depending on the purpose, polyvinyl alcohol with an extremely low degree of polymerization of about 50 to 300 can also be used. The degree of saponification of polyvinyl alcohol is approximately
40 mol% to 100 mol% is used.
Among these, those with a relatively low degree of saponification do not necessarily have sufficient water solubility, but they can be used in combination with organic solvents,
If an anionic surfactant is used, uniform dissolution is possible, so there is no particular problem in its use. Next, vinyl esters in the vinyl ester-unsaturated dicarboxylic acid monoester copolymer (B) include vinyl acetate, vinyl propionate, vinyl stearate, vinyl benzoate, vinyl saturated branched fatty acids, etc. It is common to use either alone or at least mainly. The unsaturated dicarboxylic acid monoester component is a monoester of an acid such as maleic acid or its anhydride, methylmaleic acid, fumaric acid, methylfumaric acid, itaconic acid, or glutaconic acid, and the alkyl group of the ester has 1 to 20 carbon atoms. , especially 4
~20 things can be mentioned. The acid group portion may be in the form of a salt. In addition to the vinyl ester and the unsaturated dicarboxylic acid monoester, the composition may contain an unsaturated dicarboxylic acid, a salt thereof, or an anhydride. 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.
The ratio of acid groups to ester groups in the unsaturated dicarboxylic acid monoester component is usually 5:95 to 75:25 in terms of moles; if the acid groups are too small, water solubility or water dispersibility will be impaired; On the other hand, if there are too many acid groups, there is no problem in terms of water solubility, but the releasability to dryers and calender rolls decreases, resulting in a lack of stain prevention effect. 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 At least a portion of the acid groups may be neutralized with a basic substance such as an inorganic 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 ratio of the above copolymer to polyvinyl alcohol (A) is 100 parts by weight of the former to 0.1 to 30 parts by weight of the latter.
parts by weight, and the proportion of the above copolymer should be
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. Methods for mixing polyvinyl alcohol and vinyl ester-unsaturated dicarboxylic acid monoester copolymer include adding the latter to the powder of the former in advance, mixing both in the form of an aqueous solution or aqueous dispersion, and mixing the former in the form of an aqueous solution or dispersion. Any method may be employed, such as adding the latter to an aqueous solution or vice versa. The paper is treated with an aqueous solution containing polyvinyl alcohol and a vinyl ester-unsaturated dicarboxylic acid monoester copolymer (although the latter copolymer may be dispersed in water). The concentration of alcohol is not particularly limited, but it is practical to set it to about 0.1 to 10% by weight. Note that there is no particular problem in using other polymeric components together with polyvinyl alcohol, and other additives such as latex, fillers, pigments, dyes, waterproofing agents, rust preventives, antifoaming agents,
Surfactants, plasticizers, organic solvents, thixotropic agents, etc. 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 parts by weight Vinyl acetate: Monooctyl maleate = 82:
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 The degree of polymerization is determined in the aqueous solution of the obtained copolymer.
A 4% aqueous solution of polyvinyl alcohol was prepared by adding polyvinyl alcohol powder having a saponification degree of 99.9 mol % and adding water, followed by heating and stirring. The ratio of polyvinyl alcohol and the copolymer in the aqueous solution was such that the copolymer was 10% to the 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 120 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 liner with an outer diameter of 10 cm by bar coating at 10 g/ ^m3 on a wet basis.
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 2.1CPS (20°C). The polyvinyl alcohol used in Example 1 was mixed with the aqueous solution of this copolymer to prepare a 4% aqueous solution of polyvinyl alcohol. The ratio of copolymer to polyvinyl alcohol was 10%. When a dry cloth was dipped in this aqueous solution and attached to an iron roll heated to 90℃, the peel resistance was 110.
g/cm, and almost no stains were observed 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 As shown in Table 1, the results of the iron roll peel test and heated roll paper passing using only the 4% aqueous solution of polyvinyl alcohol used in Example 1 were extremely unsatisfactory. Control Examples 2 to 4 To the 4% aqueous solution of polyvinyl alcohol used in Example 1, polyoxyethylene lauryl ether (Control Example 2), polyoxyethylene nonylphenol ether (Control Example 3), For polyvinyl alcohol
10% glycerin (Comparative Example 4) was added, and an iron roll peeling test and heated roll paper passing were performed, but the first
As shown in the table, 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 8 The same tests as in Example 1 were conducted using the following combinations of polyvinyl alcohol and copolymers. The test results are shown in Table 4. Example 7 4% aqueous solution of polyvinyl alcohol with a degree of polymerization of 1400 and a degree of saponification of 98.0 mol % Neutralized copolymer used in Example 2 (used at 7% with respect to polyvinyl alcohol) Example 8 A degree of polymerization of 1400 and a degree of saponification of 98.0 mol % aqueous solution of polyvinyl alcohol Neutralized copolymer used in Example 4 (used at 5% with respect to polyvinyl alcohol) Control example 5 4% aqueous solution of polyvinyl alcohol used in Examples 7 and 8
The same test as in Example 1 was conducted except that each of the % aqueous solutions 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 polyvinyl alcohol (A) and 0.1 to 30 parts by weight of vinyl ester-unsaturated dicarboxylic acid monoester copolymer (B). 2. The paper treating agent according to claim 1, wherein at least a portion of the ester groups of the unsaturated dicarboxylic acid monoester component in B are alkyl esters having 4 or more carbon atoms.