JPH0316437B2 - - 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. In contrast, 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, 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. The present inventors have made extensive 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, It has been found that the sizing effect of the organic 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 polydiallylamine 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.
This is thought to be due to the optimal fixation of the organic ketene dimer and the orientation of the hydrophobic groups. That is, the present invention provides a neutral paper with excellent size properties, which is characterized by containing an organic ketene dimer, a polydiallylamine derivative, and a dicyandiamide-formalin condensate. The cationic aqueous dispersion sizing agent of organic ketene dimer in the present invention is a dispersion obtained by emulsifying a compound containing an alkyl ketene dimer as a main component with a cationic emulsifier such as cationic starch. No. 55-90700, JP-A-55-98997
No., JP-A-55-116898, JP-A-55-116898,
Sizing agents such as those described in JP-A-55-132799 and JP-A-55-101998 can be used. The polydiallylamine derivative of the present invention has structural units represented by the following general formulas (), (), and (). In the formula, R ₁ and R ₂ are −CH ₃ , −CH ₂ −CH ₃ , −CH ₂ −
_CH2 -OHY represents an acid group. The dicyandiamide-formalin condensate used in the present invention is commonly used as a flocculant.
It is as described in the number. Of course, the dicyandiamide-formalin condensate may contain a modifier such as a diamine as a third component. The amount of dicyandiamide-formalin condensate added to the pulp
0.05-0.60% by weight is preferred. If it is less than 0.05% by weight, a sufficient effect of improving sizing properties cannot be obtained, and if it is more than 0.60% 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 0.05% by weight relative to the dicyandiamide-formalin condensate. It is preferably ~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. 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. All parts and percentages in the examples are by weight. Example 1 Paper with a basis weight of 60 g/m ² containing the following ingredients in the following content was hand-made, and after applying a wet pressure of 7.0 Kg/cm ³ to the wet paper.
A sample was obtained by drying for 3 minutes with a cylindrical dryer at 80°C. Mixture of bleached hardwood kraft pulp and bleached softwood kraft pulp in a weight ratio of 8:2 beaten with a beater to 350 ml at Canadian standard water level: 100 parts Heavy calcium carbonate (Escalon #200 manufactured by Sankyo Seifun Co., Ltd.): 5 parts Talc ( (manufactured by Hyogo Talc Co., Ltd.): 15 parts Poly(diallyl-dimethyl-ammonium chloride) (Percol 1697, manufactured by Allied Colloid Co., Ltd.):
It was changed to 5 levels: 0.005, 0.010, 0.10, 0.40 and 0.50 parts. Dicyandiamide-formalin condensate (manufactured by Nippon Carbide Co., Ltd. = Kafrotsu D-1000): 0.20 parts Sizing agent consisting of a cationic aqueous dispersion of alkyl ketene dimer (Haakon W, manufactured by Deitz Hercules): 0.15 parts These samples 1-2, 1-3, 1-4, 1-5 and 1-6, depending on the amount of poly(diallyl-dimethyl-ammonium chloride) internally added. Example 2 In Example 1, poly(diallyl-dimethyl-
Samples were obtained in the same manner except that the amount of ammonium chloride) added was 0.03 part, and the amount of dicyandiamide-formalin condensate added was 0.03, 0.05, 0.30, 0.60, and 0.75 parts. These samples were divided into 2-2, 2-3, 2-4, and
2-5 and 2-6. Example 3 In Example 1, poly(diallyl-dimethyl-
Samples were obtained in the same manner except that 0.1 part of polyamine sulfonate (Pass A, manufactured by Nittobo Co., Ltd.) was added instead of ammonium chloride. This sample is designated as 3. Comparative Example 1 In Example 1, poly(diallyl-dimethyl-
Samples were obtained in the same manner except that the amount of ammonium chloride (ammonium chloride) added was 0 parts. This sample is designated as 1-1. Comparative Example 2 A sample was obtained in the same manner as in Example 2 except that the amount of dicyandiamide-formalin condensate added was 0 parts. This sample is designated as 2-1. Comparative Example 3 In Example 1, poly(diallyl-dimethyl-
Samples were obtained in the same manner except that 1.0 part of cationic starch (Kate 2, manufactured by Oji National Co., Ltd.) was added instead of ammonium chloride) and dicyandiamide-formalin condensate. This sample is designated as 4. Comparative Example 4 In Example 1, poly(diallyl-dimethyl-
Samples were obtained in the same manner except that the amount of the ammonium chloride) and dicyandiamide-formalin condensate was 0 parts, and the amount of the alkyl ketene dimer sizing agent was 0.75 parts. This sample is designated as 5. The above results are summarized in Table 1.

[Table] From Table 1, by internally adding a polydiallylamine derivative and a dicyandiamide-formalin condensate together with a sizing agent consisting of an alkyl ketene dimer, dicyandiamide-formalin condensate alone or a cationic starch widely used in neutral paper can be produced. It can be seen that a much better size effect can be obtained compared to when using . Therefore, it is possible to obtain neutral paper with good sizing properties by adding a smaller amount of sizing agent.

Claims (1)

[Claims] 1 cationic aqueous dispersion of organic ketene dimer,
Contains a polydiallylamine derivative and a dicyandiamide-formalin condensate, and the content of the dicyandiamide-formalin condensate is lower than that of the pulp.
A neutral paper characterized in that the content of the polydiallylamine derivative is 0.05 to 0.60% by weight, which is 0.025 to 2.5 times the weight of the dicyandiamide-formalin condensate.