JPH0115639B2 - - Google Patents

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 PH4.5 by adding an anionic rosin sizing agent and sulfuric acid as a fixing agent. On the other hand, recently, with the aim of using cheap calcium carbonate as a filler, using waste paper containing calcium carbonate, and improving the shelf life of paper, paper has been made in a neutral pH range of around 7 to a weak alkaline pH of around 9. It has become necessary to make so-called neutral paper. However, it is known that 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. There is. Currently, commercially available neutral sizing agents include organic ketene dimers, types with reactive groups for cellulose such as substituted cyclic dicarboxylic anhydrides, epoxidized higher fatty acid amides, and cationized styrene-maleic anhydride copolymers. There are types that are fixed to anionic cellulose by cationization, such as coalescence and cationization petroleum resins. 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 whose main component is an organic ketene dimer such as an alkyl ketene dimer is superior in terms of sufficient sizing properties and workability even when added in small amounts. Particularly recently, a sizing agent containing a cationic aqueous dispersion of an organic ketene dimer has 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 polymeric substances such as cationic starch, dicyandiamide-formalin condensate, and polyaminopolyamide epichlorohydrin together with organic ketene dimer; However, it was not possible to obtain sufficiently satisfactory results using the polymeric substance 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. As a result of extensive studies in order to solve the various problems mentioned above, the present inventors found that a cationic aqueous dispersion of an organic ketene dimer as a sizing agent was mixed with a water-soluble aluminum salt and a degree of substitution of 0.035 to 0.070. Third
By incorporating the organic ketene dimer into the paper together with the grade amine starch derivative, the sizing effect of the organic ketene dimer can be maximized, and neutral paper with sufficient sizing properties can be obtained with a small amount of sizing agent added. I discovered that. The reason for this is that normally tertiary amine starch derivatives exhibit only extremely weak cationic properties at pH 7 or higher, but tertiary amine starch derivatives with a degree of substitution of 0.035 to 0.070, which has a higher degree of substitution than general cationic starches, are water-soluble aluminum It is thought that by coexisting with a salt, anionic substances in the paper stock can be efficiently neutralized, and the fixation of organic ketene dimers and the orientation of hydrophobic groups can be optimized. That is, the present invention provides a cationic aqueous dispersion of an organic ketene dimer, a water-soluble aluminum salt, and a tertiary amine starch derivative having a degree of substitution of 0.035 to 0.070. It provides sex paper. Examples of the cationic aqueous dispersion of organic ketene dimer in the present invention include JP-A-55-90700;
JP-A-55-98997, JP-A-55-116898, JP-A-55-116898, JP-A-132799, JP-A-55-
Sizing agents such as those described in No. 101998 can be used. The amount of the cationic aqueous dispersion of organic ketene dimer added to neutral paper varies depending on the target paper size, but
0.05-0.60% by weight is preferred. The water-soluble aluminum salts of the present invention include aluminum sulfate (sulfate band), aluminum chloride,
Polyaluminum chloride or the like can be used. The third type with a degree of substitution of 0.035 to 0.070 used in the present invention
For example, starch derivatives can be produced by reacting starch with ethyleneimine to form aminoethylated starch, by reacting starch with polyalkylene polyamine, or by reacting starch with a halogenated amine such as 2-dimethylaminoethyl chloride under alkaline conditions. It can be obtained by a reaction method or the like. The basic starch used is unmodified starch derived from all plant sources such as corn, corn, tapioca, and wheat, as well as denatured starch that has been subjected to mild oxidative conversion, enzymatic conversion, or acid hydrolysis. I can do it. The degree of substitution (DS) of the tertiary amine starch derivatives suitable for use in the present invention, ie the average number of cationic groups per anhydroglucose unit of the starch molecule, is between 0.035 and 0.070. Many commercially available tertiary amine starch derivatives have a degree of substitution of 0.035 or less, and even when they are used, sufficient size effects cannot be obtained. Tertiary amine starch derivatives having a degree of substitution of 0.070 or more are undesirable because they have too strong cationic strength and produce fine foam-like aggregates during paper making. In addition, quaternary salts exhibit cationic properties even at pH 7 or higher.
Even with grade ammonium starch derivatives, satisfactory size effects could not be obtained. In the present invention, a water-soluble aluminum salt and a tertiary amine starch derivative with a degree of substitution of 0.035 to 0.070 are used together in order to enhance the size effect of the cationic aqueous dispersion of organic ketene dimer. The content is 0.1 to 0.1 by weight for tertiary amine starch derivatives with a degree of substitution of 0.035 to 0.070.
Preferably it is 5.0 times. If it is less than 0.1 times, the synergistic effect of the combination of both will not be fully demonstrated, and 5.0
If it exceeds twice that, it is not preferable because it becomes difficult to adjust the pH during paper making. The neutral paper in the present invention is paper that is made at a pH of 7 to 9, rather than around 4.5 like conventional acidic paper. 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. Note that the present 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 g/m ² containing the following components in the following content was hand-made, and after applying a wet pressure of 7.0 Kg/cm ² to the wet paper.
A sample was obtained by drying for 3 minutes with a cylindrical dryer at 80°C. A mixture of hardwood bleached kraft pulp and softwood bleached kraft pulp in a weight ratio of 8:2 beaten to 350 ml using a heater at Canadian standard water level: 100 parts heavy calcium carbonate (Escalon #200 manufactured by Sankyo Seifun Co., Ltd.): 5 parts talc ( (manufactured by Hyogo Clay Co., Ltd.): 15 parts Sulfuric acid band: 0.6 parts Tertiary amine starch derivative prepared by the method of the modification example described below so as to change the degree of substitution to three levels: 0.035, 0.050, and 0.070: 0.6 parts Alkyl ketene dimer A sizing agent consisting of a cationic aqueous dispersion of (Haakon W manufactured by Deitz Hercules): 0.15 parts These samples were sized 1-2, 1-3, 1-3,
and 1-4. Example 2 In Example 1, the amount of sulfuric acid band added was 0.03,
Samples were obtained in the same manner except that the amounts were 0.06, 3.0, and 4.2 parts, and the degree of substitution of the tertiary amine starch derivative was 0.50. These samples were tested at 2-2, 2-3, and 2 depending on the amount of sulfuric acid added.
-4 and 2-5. Example 3 All the same as in Example 1 except that the degree of substitution of the tertiary amine starch derivative was 0.050 and the amount of the sizing agent consisting of a cationic aqueous dispersion of alkyl ketene dimer was 0.05, 0.30, 0.60 and 0.75 parts. Samples were prepared using the same method. These samples were designated as 3-1, 3-2, 3-3, and 3-4, respectively, depending on the amount of alkyl ketene dimer sizing agent added. Comparative Example 1 Samples were obtained in the same manner as in Example 1 except that the degree of substitution of the tertiary amine starch derivative was changed to two levels, 0.030 and 0.080. These samples are designated as 1-1 and 1-5, respectively. Comparative Example 2 A sample was obtained in the same manner as in Example 1 except that a quaternary ammonium starch derivative having a degree of substitution of 0.050 was added instead of the tertiary amine starch derivative. This sample is designated as 1-6. Comparative Example 3 A sample was obtained in the same manner as in Example 2 except that the amount of sulfuric acid band added was 0 parts. This sample will be referred to as 2-1. Comparative Example 4 A sample was obtained in the same manner as in Example 1 except that the amount of tertiary amine starch derivative added was 0 parts. This sample is designated as 1-7. Starch Modification Example 120 parts of corn starch are slurried in 1880 parts of water containing 48 parts of sodium hydroxide. Beta-diethylaminoethyl chloride is added to this slurry depending on the degree of substitution required. The resulting mixture is then heated until the temperature of the contents is
100 in a continuous steamer adjusted to 150 degrees C.
Pass at a flow rate of cc/min. The solids content of the resulting tertiary amine starch derivative dispersion is 6%. When producing a quaternary ammonium starch derivative, it can be obtained by adding 3-chloro-2-hydroxypropyltrimethylammonium chloride in place of beta-diethylaminoethyl chloride in the above procedure. The above results are summarized in Table 1.

【table】

[Table] There were no problems regarding papermaking, except for the fact that fine foam-like aggregates were generated during papermaking in sample number 1-5, and a change in papermaking pH over time was observed in sample number 2-5. It was not recognized. (Note) Papermaking PH is a measured value for paper stock with a solid content concentration of 0.1%. The Steckicht size degree required for writing paper is 20
More than seconds. 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%. From Table 1, the sulfate band and degree of substitution are 0.035
By internally adding a tertiary amine starch derivative of ~0.070 along with a sizing agent consisting of a cationic aqueous dispersion of an alkyl ketene dimer, the conventionally commonly used tertiary amine starch derivative with a degree of substitution of 0.035 or less or It is clear that a much better size effect can be obtained compared to when using a quaternary ammonium starch derivative.
Therefore, according to the method of the present invention, it is possible to obtain neutral paper with good sizing properties by adding a smaller amount of sizing agent.

Claims (1)

[Claims] 1. A cationic aqueous dispersion of an organic ketene dimer,
Water-soluble aluminum salt, and degree of substitution from 0.035
Neutral paper characterized in that it contains 0.070 of a tertiary amine starch derivative. 2 The content of water-soluble aluminum salt is the degree of substitution.
Claim 1, which is 0.1 to 5.0 times by weight relative to the tertiary amine starch derivative of 0.035 to 0.070.
Neutral paper as described in section. 3. The content of the cationic aqueous dispersion of organic ketene dimer is 0.05 to 0.60% by weight based on the pulp.
Neutral paper according to claim 1.