JPS6242079B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to neutral paper with excellent sizing. More specifically, it does not contain sodium sulfate and has water solubility obtained by saponifying the vinyl acetate portion of a copolymer of a monomer represented by the following general formula () and vinyl acetate. Polyvinyl alcohol (hereinafter polyvinyl alcohol is referred to as PVA)
It relates to an neutral paper with excellent sizing, characterized by containing 0.1 to 5% by weight (abbreviated as ). However, R ₁ , R ₂ , and R ₃ are alkyl groups or hydrogen, at least two of which are alkyl groups, and the total number of carbon atoms is 5 or more. Paper is a hydrophilic porous material whose main raw material is pulp, but it is not practical if it is simply made from pulp. Therefore, paper that can be used for practical purposes can only be obtained by using sizing agents, fillers, and various paper chemicals. There are many evaluation items for the practical physical properties of paper, including sizing, which includes printing ink bleeding, permeability, writing ink bleeding, and in the case of base paper for processing, permeability of processing fluids and associated effects. This is an important property that determines the physical properties of processed paper. Most of the conventionally used sized papers are manufactured by fixing a rosin-based sizing agent onto pulp fibers through the intervention of sulfuric acid. However, when sulfuric acid is used as a fixative, the sulfate roots of sulfuric acid make the paper acidic during the manufacturing process, which not only corrodes calender rolls, dryer rolls, and other metals that come into contact with the paper during the process. This may have a negative effect on the strength and durability of the paper, and may also cause problems with certain types of printing. In addition, it is widely known that a major practical problem with paper made using banal sulfate soil is that metals that come into contact with it are extremely susceptible to rust. Various measures are required to prevent rust from forming on printing paper that is used for binding. Under these circumstances, in recent years, improving the size of acid-free paper made without adding banal sulfate has been brought to the fore as a social need. On the other hand, PVA is a water-soluble polymer compound with excellent oil resistance and film-forming properties, and has been widely used as a surface sizing agent for paper and paperboard. It has been pointed out that the physical properties, such as, are actually deteriorated. In addition, modified PVA in which a branched fatty acid vinyl ester is introduced into PVA is known, and its use in paper processing is known from Japanese Patent Publication No. 46-25521, etc., but in recent years social demand for such modified PVA has increased. There has been no disclosure so far of its use in increasing the size of acid-free paper, which is increasing in number. In view of these circumstances, the inventors of the present invention have conducted intensive studies to obtain neutral paper with excellent size properties. An acid-free paper characterized by containing 0.1 to 5% by weight of water-soluble modified PVA obtained by saponifying the vinyl acetate portion of a copolymer with vinyl acetate and vinyl acetate, is JIS-
The Steckigt sizing degree with P-8122 is 9 seconds or more, which is extremely excellent in sizing degree.Since it does not contain sodium sulfate, it also has excellent strength, printability, and durability, and it does not come in contact with metal. We have discovered that even when used in metals, it has excellent effects such as not causing any rust on metals.
This completes the present invention. However, R ₁ , R ₂ , and R ₃ are alkyl groups or hydrogen, at least two of which are alkyl groups, and the total number of carbon atoms is 5 or more. Further, the neutral paper of the present invention has the advantage that it can contain calcium carbonate, which is a filler for paper manufacturing, which is advantageous not only from a performance standpoint but also from an economic standpoint. That is, as mentioned above, most of the rosin-based sizing agents that are generally used as paper-making sizing agents are used under acidic conditions due to aluminum sulfate, but when using the aforementioned advantageous calcium carbonate as a filler, This causes the inconvenience that calcium carbonate decomposes and foams. The neutral paper of the present invention also solves this problem, and by making it possible to use inexpensive calcium carbonate as a filler, it is possible to provide a neutral paper with excellent economic efficiency. The modified PVA used in the present invention is water-soluble modified PVA obtained by saponifying the vinyl acetate component of a copolymer containing a monomer represented by the following general formula () and vinyl acetate.
It is. Here, in formula (), R ₁ , R ₂ , R ₃ represent an alkyl group or a hydrogen atom, and R ₁ , R ₂ , R ₃
At least two of them are alkyl groups, and the total number of carbon atoms is 5 or more. If there is only one alkyl group among R ₁ , R ₂ and R ₃ , good performance cannot be obtained, probably because it is cleaved when the vinyl acetate component of the copolymer is saponified. If the total number of carbon atoms in R ₁ , R ₂ , and R ₃ is less than 4, good performance cannot be obtained, probably because hydrophobicity is small. Monomers represented by the general formula () used in the present invention include 1,1,3,3-tetramethylbutyric acid vinyl ester, 2,2,4,4-tetramethylvaleric acid vinyl ester, and branched fatty acids having an average carbon number of 10. Vinyl ester (Veova-10, manufactured by Ciel)
etc. Among them, Veova-10 is suitable. The monomer represented by the general formula () differs depending on the number of carbon atoms, but it is 0.1% relative to vinyl acetate.
It is preferable to use up to 1.5 mol%. 0.1 mol%
If it is below, remarkable performance will not be exhibited. Furthermore, if the amount exceeds 1.5 mol%, the water solubility of the modified PVA will decrease. A small proportion of other monomer components other than the monomer represented by the general formula () may also be used in combination within a range that does not impair the object of the present invention. Although it is preferable for the vinyl acetate component to be completely saponified in terms of physical properties such as water resistance and strength, a portion of the vinyl acetate component may be left unsaponified. degeneration
The degree of polymerization of PVA is preferably 200 to 3000. A low degree of polymerization tends to be unfavorable in terms of physical properties, such as a decrease in strength. If the degree of polymerization is too high, exceeding 3000, the viscosity of the aqueous solution will increase, causing trouble in the coating process, which is not preferable. In the present invention, the modified PVA needs to be contained in an amount of 0.1 to 5% by weight based on the paper, for example, by a method such as coating, although this will vary depending on the required performance of the paper. If it is less than 0.1% by weight, no remarkable performance will be exhibited. Moreover, using more than 5% by weight is not desirable for general purposes because it increases the cost of raw materials and chemicals. When applying, the modified PVA of the present invention can usually be used alone as an aqueous solution, but modified PVA containing a carboxyl group, other modified PVA, or unmodified PVA can be used as long as the purpose of the present invention is not impaired. They can also be used in combination.
Further, for the purpose of preventing adhesion to the drying roll after coating, a release agent selected from the group of starch, wax emulsion, and various activators can be used in combination. Other glycerin, diethylene glycol,
Polyhydric alcohols such as ethylene glycol, plasticizers, carboxymethyl cellulose, starch and its derivatives, synthetic water-soluble polymers such as styrene-maleic anhydride copolymers, styrene-acrylic acid copolymers, as well as calcium carbonate and kaoli Mineral pigments such as night clay, loite clay, and sachin white can also be used together. The base paper used to obtain the neutral paper of the present invention may be obtained from softwood pulp, hardwood pulp, or a mixture thereof, and may further contain fibers such as synthetic fibers, man-made fibers, and synthetic pulp. Moreover, not only virgin pulp but also broken paper, waste paper, etc. may be mixed. In addition, paper strength enhancers, water promoters, antifoaming agents,
There is no harm in containing paper chemicals commonly used in the production of neutral paper, such as fillers such as clay and calcium carbonate. Next, the present invention will be explained in more detail with reference to examples, but the present invention is not limited to these examples. In the examples, parts are by weight unless otherwise specified. Example 1 Polymerization was carried out using vinyl acetate and a branched fatty acid vinyl ester having an average carbon number of 10 (Veova-10, manufactured by Ciel) in a methanol solution with α,α′-azobisisobutyronitrile as an initiator. A copolymer was obtained. These copolymers were dissolved in methanol, saponified using sodium hydroxide as a catalyst, and purified by conventional methods to obtain modified PVA. Using softwood bleached kraft pulp (NBKP) beaten to a freeness of 590 cc, the above modified PVA was added to 1.9 g/m ² of base paper with a basis weight of 65 g/m ² which was made using a hand paper machine without adding banal sulfate. After applying size press coating and drying, it was left in a test room at 20° C. and 65% RH overnight, and the Steckigt sizing degree was measured according to JIS P-8122. The results are shown in Table-1. The size degree of the paper base paper is 0
In contrast, the neutral paper of the present invention exhibited high size properties of 13 to 9 seconds. The results are shown in Table-1. Comparative Example 1 Using ordinary unmodified PVA instead of the modified PVA used in Example 1, the Steckigt sizing degree of paper coated under the same conditions as in Example 1 was 0 seconds, and no sizing effect was observed. Nakatsuta. The results are in Table-1
Also listed in

[Table] Comparative Example 2 Copolymer components of modified PVA used in Example 1
Modified in the same manner as in Example 1 except that trimethyl acetate vinyl ester was used instead of Veova-10.
As shown in Table 2, no size effect was observed for the paper coated with PVA.

[Table] Example 2 Basis weight 64 containing 10% calcium carbonate using a 3:1 mixed pulp of softwood bleached kraft pulp (NBKP) and hardwood bleached kraft pulp (LBKP)
2.5 g/m ² of the modified PVA obtained in Example 1 was applied to the base paper.
Size press coating to give g/m ² , drying, 20
After being left overnight in a test room at ℃ and 65% RH, JIS P
-8122, Steckicht size was measured. The results are shown in Table-3. It showed a high sizing degree of 14 to 20 seconds, whereas the sizing degree of the base paper was 0 seconds.

【table】

Claims (1)

[Scope of Claims] 1. A water-soluble product that does not contain vanium sulfate and is obtained by saponifying the vinyl acetate portion of a copolymer of a monomer represented by the following general formula () and vinyl acetate. An neutral paper with excellent sizing, characterized by containing 0.1 to 5% by weight of modified polyvinyl alcohol having the following properties. However, R ₁ , R ₂ , and R ₃ are alkyl groups or hydrogen, at least two of which are alkyl groups, and the total number of carbon atoms is 5 or more.