JPS6059195A - Neutral paper - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] The present invention relates to neutral paper with excellent size properties.

Conventionally, paper has been made in an acidic range around pH 4.5 by adding an anionic sizing agent and sulfuric acid as a fixing agent. On the other hand, recently, paper has been produced in a neutral range of around PH7 to a slightly alkaline range of around PH9 for the purpose of using cheap calcium carbonate as a filler, using waste paper containing calcium carbonate, and improving the shelf life of paper. It has become necessary to perform so-called neutral paper making. However, in the pH range of 7 or higher, sulfuric acid band does not act effectively as a fixing agent for rosin size, so rosin size cannot be used, and sizing with various neutral sizing agents is required.

Currently, commercially available neutral sizing agents include organic ketene dimers, typed epoxylated higher fatty acid amides with reactive groups for cellulose such as substituted cyclic dicarboxylic anhydrides, and cationized styrene-maleic anhydride copolymers. ,
There are types such as cationized petroleum resins that are fixed to anionic cellulose by being cationized.

Among these, substituted cyclic dicarboxylic acid anhydrides have problems with workability because they need to be emulsified immediately before addition, and cationic neutral sizing agents require the addition of a large amount of sizing agent to obtain the desired sizing degree. This causes problems such as paper strength reduction and process stains. Therefore, a neutral sizing agent mainly composed of an organic ketene dimer such as an alkyl ketene dimer can provide sufficient sizing properties by adding a small amount, and is excellent in terms of workability. Particularly recently, sizing agents containing a cationic aqueous dispersion of an organic ketene dimer have been widely used for the purpose of improving the fixation of anionic cellulose fibers.

However, these sizing agents are expensive, and when added in large amounts, they significantly reduce the friction coefficient of the paper surface, causing problems in handling in subsequent processes, so it is difficult to achieve sufficient sizing properties with the minimum amount added. , is especially necessary. For this purpose, it is known that paper contains cationic water-soluble polymer substances such as cationic starch, dicyandiamide-formalin condensate, and polyaminopolyamide epichlorohydrin together with organic ketene dimer. Sufficient results could not be obtained using polymeric substances alone. The present invention improves these problems.

An object of the present invention is to provide a neutral paper that exhibits excellent sizing properties with the addition of a small amount of sizing agent.

The present inventors have made intensive studies to solve the various problems described above, and have found that by incorporating an organic ketene dimer, which is a sizing agent, into paper together with a polydiallylamine derivative and a dicyandiamide-formalin condensate, the present inventors have found that organic It has been found that the sizing effect of the ketene dimer can be maximized and that neutral paper with sufficient sizing properties can be obtained with a small amount of sizing agent added. The reason for this is that polysialylamine derivatives, which are cations with relatively low molecular weight and high charge density, and dicyandiamide-formalin condensates, which are cations with lower charge density, efficiently neutralize anionic substances in the paper stock, and It is thought that the fixation of polymers and the orientation of hydrophobic groups are optimal.

That is, the present invention provides a neutral paper with excellent size properties, which is characterized by containing an organic ketene dimer, a polysialylamine derivative, and a dicyandiamide-formalin condensate.

As the sizing agent for the organic ketene dimer in the present invention, 1
For example, JP-A-55-90700, JP-A-55-989
Sizing agents such as those described in No. 97 and JP-A-55-11 can be used.

The polydiallylamine derivative of the present invention has the following general formula (1
) % (1) and (厘) are structural units.

In the formula, R1 and R2 are -CH3, -CH, -CH,, -CH
, -C)I, -0HY represent an acid group.

The dicyandiamide-formalin condensate used in the present invention is commonly used as a flocculant, and its specific manufacturing method is, for example, as described in Japanese Patent Publication No. 36-23231.Of course, This dicyandiamide-formalin condensate may contain a modifier such as diamine as a third component.The amount of the dicyandiamide-formalin condensate added is 0.605 to 0.60% by weight relative to the valve force. Preferably. If it is less than 0.05% by weight, a sufficient size improvement effect cannot be obtained;
If it exceeds 60% by weight, it is not only excessive and uneconomical, but also deteriorates the texture of the paper, which is not preferable.

In the present invention, a polydiallylamine derivative and a dicyandiamide-formalin condensate are used together in order to enhance the sizing effect of the organic ketene dimer sizing agent, but the content of the polydiallylamine derivative is 0.0% by weight relative to the dicyandiamide-formalin condensate. It is preferable that it is 0.05 to 2.0 times. If it is less than 0.05 times, the synergistic effect of the combined use of both will not be sufficiently exhibited, and if it exceeds 2.0 times, it will deteriorate the texture of the paper, which is not preferable.

In the present invention, the acid-neutral paper has a PH
This paper is made at a pH of 7 to 9, rather than around 4.5.

The neutral paper contains additives normally used in paper making, such as fillers, dyes, dry paper strength enhancers, wet paper strength enhancers, and retention improvers, as necessary. It is also possible to apply starch, polyvinyl alcohol, various surface sizing agents, pigments, dyes, etc., singly or in combination, on the surface of the neutral paper of the present invention using a size press or the like, if necessary.

The present invention will be described in detail below with reference to Examples. In addition,
The invention is not limited to the examples. In the examples, all parts and percentages are by weight.

Example 1 A paper with a basis weight of 60 f/wl containing the following components in the following content was hand-made and wet paper was coated with 7. After applying a mixed pressure of Oky/c++I, it was dried for 3 minutes in a cylindrical dryer at 80° C. to obtain a sample.

A mixture of bleached hardwood pulp and softwood bleached kraft pulp in a weight ratio of 8:2: 100 parts heavy calcium carbonate (Niscalon manufactured by Sankyo Seifun Co., Ltd. $200)
): 5 parts talc (manufactured by Hyogo Talc Co., Ltd.) 2 15 parts poly(saryl-dimethyl-ammonium chloride) (Percoll 1697, manufactured by Allied Colloid Co., Ltd.): 0.0
05.0.010.0.10.0°40 and 0.50
It was changed to 5 levels.

Dicyandiamide-formalin condensate (manufactured by Nippon Carbide Co., Ltd.; Caflock D-1000): 0.20 parts Sizing agent consisting of a cationic aqueous dispersion of alkyl ketene dimer (Dick Bercules ■, +Jl---9)
・）■「 ＼ ・ 01 ☆1 each 1-2.1-
3.1-4.1-5 and 1-6.

Example 2゜Example 1. The amount of poly(diallyl-dimethyl-ammonium chloride) added was 0.03 parts, and the amount of dicyandiamide-formalin condensate was 0.03.0 parts.
．． Samples were obtained in the same manner except that 0.05.0.30.0.60 and 0.75 parts were used. These samples were 2-2.2-3.2-4.2-5 and 2-6, respectively, depending on the amount of dicyandiamide-formalin condensate added.
shall be.

Example 3゜Example 1. Samples were obtained in the same manner except that 0.1 part of polyamine sulfonate (Bath A manufactured by Nittobo Co., Ltd.) was added instead of poly(diallyl-dimethyl-ammonium chloride). This sample is designated as 3.

Comparative example 1゜ Samples were obtained in the same manner. This sample is designated as 1-1.

Comparative Example 2゜Example 2. Samples were obtained in the same manner except that the amount of dicyandiamide-formalin condensate added was 0 parts for odor. This sample is designated as 2-1.

Comparative example 3゜Example 1. Samples were obtained in the same manner except that 1.0 part of cationic starch (Kate 2, manufactured by Tamago National Co., Ltd.) was added instead of poly(diallyl-dimethyl-ammonium chloride) and dicyandiamide-formalin condensate. This sample is designated as 4.

Comparative example 4゜Example 1. Samples were obtained in the same manner except that the amount of poly(diallyl-dimethyl-ammonium chloride) and dicyandiamide-formalin condensate was 0 parts, and the amount of alkyl ketene dimer sizing agent was 0.75 parts. . This sample is designated as 5.

The above results are summarized in Table 1. Table □ (Note)
The Steckigt size degree required for writing paper is at least 1
It is 5 seconds or more, preferably 20 seconds or more. From the viewpoint of quality and economy, it is preferable to obtain a sizing degree of 20 seconds or more when the amount of the alkyl ketene dimer sizing agent added to the pulp is around 0.15%.

The grade of the formation is A is good and %D is bad. In terms of quality, a minimum of C or higher is required, but A%B is preferable.

The comprehensive evaluation is an evaluation that takes into account economic efficiency based on blending cost in addition to the above-mentioned size degree and paper formation evaluation.From Table 1, it has no practical meaning unless it is ◎ or O. By internally adding a formalin condensate together with a sizing agent consisting of an alkyl ketene dimer, a far superior sizing effect can be obtained compared to the use of dicyandiamide-formalin condensate alone or cationic starch, which is widely used in neutral paper. It is possible to obtain neutral paper with good size properties.

Claims (1)

[Scope of Claims] α) A neutral paper characterized by containing an organic ketene dimer, a polydiallylamine derivative, and a dicyandiamide-formalin condensate. Q) The content of polydiallylamine derivative is 0.05 to 2.0 by weight based on the dicyandiamide-formalin condensate.
The neutral paper according to claim 1, which is twice as large. The neutral paper according to claim 2, which is