JP4336964B2 - Paper thickness increasing agent and paper strength increasing agent - Google Patents

Description

  The present invention relates to a paper thickness increasing agent and a paper strength enhancing agent, for example, a paper thickness increasing agent and a paper strength that can be suitably used when increasing the paper thickness and paper strength of a sheet obtained by papermaking a pulp raw material. Relates to enhancers.

In recent years, from the viewpoint of environmental conservation and the establishment of a recycling society, in the paper market, light and high-quality paper and paper with a high deinked pulp ratio obtained from used paper are desired.
In order to respond to such market needs, it is known that when the basis weight of paper is simply lowered or the ratio of deinked pulp in the paper is increased, the paper becomes thinner and the quality deteriorates.
Therefore, as a method of satisfying the required quality and reducing the weight of paper, a method of filling a filler such as an inorganic substance between pulp fibers (Patent Document 1: Japanese Patent Laid-Open No. 3-124895, etc.), between pulp fibers Various paper thickness increasing methods such as a method of forming voids in the paper (Patent Document 2: Japanese Patent Laid-Open No. 5-230798, etc.) and a method of adding a paper thickness improver during papermaking have been tried.
However, although these paper thickness increasing methods have the disadvantage that the paper thickness is increased but the paper strength is remarkably impaired, a paper satisfying all practically required qualities can be obtained. It ’s hard to say.

On the other hand, from the viewpoint of resolving the shortage of forest resources, there is a high expectation for recycling of used paper, and in recent years, recycling of used paper has been actively performed. However, since waste paper pulp has damaged fibers, when a large amount of recycled paper is used to produce recycled paper or the like, the paper strength is reduced and the required strength cannot be exhibited.
For this reason, when manufacturing paper products using waste paper pulp, various paper strength enhancers are used for the purpose of preventing the strength reduction.

  The paper strength enhancement effect when using a paper strength enhancer is due to the hydrogen bonding force between the hydroxyl group in the cellulose molecule and the side chain in the paper strength enhancer. Examples of the paper strength enhancing method include adding a cationized starch at the time of paper making (Patent Document 3: JP 62-45794 A, Patent Document 4: JP 11-12979 A), an acrylamide compound (Patent Document 5: Japanese Patent Laid-Open No. 63-50597, Patent Document 6: Japanese Patent Laid-Open No. 5-140893) have been developed.

By the way, in order to meet the market needs described above, it is desirable to develop a paper additive having both functions of increasing paper strength and increasing paper thickness. It is just something that can be demonstrated.
Further, in Patent Document 7 (Japanese Patent Laid-Open No. 2001-248100), although both functions of increasing paper strength and increasing paper thickness are exhibited, both functions are not sufficiently exhibited to a degree that can be satisfied in practice. is the current situation. In addition, there has been no paper additive made of a natural material that satisfies both the functions of increasing paper strength and increasing paper thickness in a one-component system and is environmentally friendly.

Japanese Patent Laid-Open No. 3-124895 JP-A-5-230798 JP-A-62-45794 JP-A-11-12979 JP-A 63-50597 Japanese Patent Laid-Open No. 5-140893 JP 2001-248100 A

  The present invention has been made in view of such circumstances, and can be added in the papermaking process to increase the paper strength and paper thickness of the resulting paper, and is also a natural material excellent in environmental adaptability. An object of the present invention is to provide a paper thickness increasing agent and a paper strength enhancing agent comprising

  As a result of intensive studies to solve the above problems, the present inventors have found that the cationized dextrin, which is a natural material, preferably has a nitrogen content of 0.5 to 4.0% by mass and a number average molecular weight. When the cationized dextrin of 500 to 100,000 has both functions of enhancing paper strength and increasing paper thickness, and adding this to paper or board making, the ratio of used paper is high In this case, it was found that a high-quality paper having sufficient strength and thickness was obtained, and the present invention was completed.

That is, the present invention
1. A paper thickness increasing and paper strength enhancing agent characterized by comprising a water-soluble cationized roasted dextrin having a nitrogen content of 0.5 to 4.0% by mass and a number average molecular weight of 500 to 8000,
2. A paper thickness increase and paper strength enhancer of 1 , wherein the nitrogen content is 0.8-3.0% by mass .

  By adding the additive comprising the cationized dextrin of the present invention in the paper making process, the paper strength enhancing effect is exhibited without adding a conventional paper strength enhancing agent, and the paper thickness It is possible to obtain sufficient paper. In addition, since this additive has both the properties of increasing the paper thickness and enhancing the paper strength, it is not necessary to use two types of additives having the respective properties. Shortening can be achieved. Furthermore, since it is made of a cationized dextrin derived from a natural product, it is excellent in environmental adaptability and can solve pollution problems such as wastewater pollution.

As described above, the paper thickness increasing agent and the paper strength enhancing agent (hereinafter collectively referred to as a paper additive) according to the present invention are composed of a cationized dextrin.
Here, the cationized dextrin is obtained by cationizing a dextrin obtained by decomposing starch and reducing the molecular weight with various cationizing agents.
In the present invention, as the dextrin, dextrin obtained by decomposing starch using various known methods can be used. For example, heat, acid, enzyme, oxidation treatment, etc. are used to decompose and reduce the molecular weight in a dry or wet manner. Things can be used as raw materials. Specific examples include roasted dextrins such as white dextrin, yellow dextrin, and British gum, enzyme-degraded dextrin, acid-treated starch, oxidized starch, and the like.

  The raw material starch for dextrin production is not particularly limited and can include various commonly used starches such as corn starch, tapioca starch, wheat starch, potato starch, sweet potato starch, and rice starch. Or modified starch obtained by physically or chemically treating these starches. These starches can be used singly or in combination of two or more.

  The cationizing agent is not particularly limited, and various known cationizing agents can be used. For example, 3-chloro-2-hydroxypropyltrimethylammonium chloride, glycidyltrimethylammonium chloride, N, N- Examples include quaternary ammonium salts such as dimethyl-1-chloro-2-hydroxypropylammonium chloride, tertiary amine salts such as 2-chloroethyldiethylamine hydrochloride, 2-chloroethyldimethylamine hydrochloride, and the like. It can be used alone or in combination of two or more. Among these, in consideration of actual operation, it is preferable to use a quaternary ammonium salt which is economical.

  The cationization method is not particularly limited, and various known methods can be used. For example, in an aqueous reaction, a cationizing agent is added to a dextrin solution in the presence of an alkali catalyst such as sodium hydroxide. The reaction is performed at 30 to 100 ° C., an alkali catalyst such as sodium hydroxide and a cationizing agent are added to a solution obtained by adding a hydrophilic organic solvent such as methanol or isopropyl alcohol to dextrin, and the reaction is performed at 30 to 100 ° C. And a method in which a dextrin is slightly moistened with a small amount of water or an organic solvent, and a cationizing agent is added to the dextrin.

  As the cationized dextrin in the present invention, the molecular weight is not particularly limited as long as it is obtained by the above-mentioned raw materials, production methods, etc., but the point of increasing the paper thickness increasing effect and the paper strength enhancing effect. Therefore, the nitrogen content is preferably 0.5 to 4.0% by mass, more preferably 0.7 to 3.7% by mass, and still more preferably 1.0 to 3.0% by mass. The nitrogen content is a value measured by a semi-micro Kjeldahl method.

For the same reason, the number average molecular weight of the cationized dextrin is preferably 500 to 100,000, more preferably 700 to 90,000, still more preferably 700 to 20,000. The number average molecular weight is a value measured by gel permeation chromatography (GPC).
In particular, a cationized dextrin having both the nitrogen content in the above-described range and a number average molecular weight is most suitable. By using such a cationized dextrin as an additive for paper, the effect of improving the paper thickness and the paper obtained It becomes possible to further improve the force enhancement effect.

The additive for paper comprising a cationized dextrin in the present invention is used by being added to an aqueous dispersion of pulp, and is a disaggregation process, a ripening process, a floatation process, and a sheet process, which are paper product manufacturing processes. It can add to the pulp slurry of arbitrary processes, such as as needed. In this case, the amount of addition is not particularly limited, but is preferably 0.05 to 5% by mass, particularly preferably 0.2 to 4% by mass, based on the absolute dry mass of the pulp. If the amount is less than 0.05% by weight, the effect of adding the paper additive may not be sufficiently exhibited. On the other hand, even if the amount exceeds 5% by weight, the effect corresponding to the amount added cannot be obtained. , It becomes economically disadvantageous.
When the paper additive of the present invention is added to the paper product manufacturing process, it may be added directly into the system of each of the above processes, and once an aqueous solution is prepared, this aqueous solution is also added to the system. May be.
The paper additive of the present invention includes various additives used in normal paper product manufacturing processes such as fillers, sizing agents, yield improvers, freeness improvers, other paper strength improvers, and paper thickness enhancers. Can also be used together.

EXAMPLES Hereinafter, although a manufacture example, an Example , a reference example, and a comparative example are given and this invention is demonstrated more concretely, this invention is not limited to the following Example.

[Production Examples 1 to 3] Production of cationized dextrin 500 g of roasted dextrin (white dextrin, Hydex 50, manufactured by Nippon Corn Starch Co., Ltd.) and 750 g of tap water are charged into a 2 L reaction flask, and the dextrin suspension is prepared. Prepared. Next, the suspension was heated to an internal temperature of 80 ° C. to dissolve dextrin, and then cooled to an internal temperature of 45 ° C. To this solution, glycidyltrimethylammonium chloride (purity: 72% by mass) (manufactured by Sakamoto Yakuhin Kogyo Co., Ltd.) as a cationizing agent was added in 277 g in Production Example 1, 194 g in Production Example 2, and 103 g in Production Example 3. While stirring this solution, a 5% aqueous sodium hydroxide solution was further added until the pH in the system reached 11.0 to 12.0, and the reaction was performed for 16 hours to obtain cationized dextrin CD1 to CD3.

[Production Example 4] Production of cationized dextrin After 685 g of roasted dextrin (solid content: 73% by mass) (KDL, manufactured by Nippon Corn Starch Co., Ltd.) and 564 g of tap water were added to a 2 L reaction flask, 225 g of glycidyltrimethylammonium chloride similar to Production Example 1 was added, and while stirring this solution, a 5% sodium hydroxide aqueous solution was further added until the pH in the system reached 11.0 to 12.0, and the reaction was performed for 16 hours. And cationized dextrin CD4 was obtained.

[Production Example 5] Production of cationized dextrin 500 g of roasted dextrin (yellow dextrin, Hydex 128, manufactured by Nippon Corn Starch Co., Ltd.) and 750 g of tap water were charged into a 2 L reaction flask to prepare a dextrin suspension. . Next, this suspension was heated to an internal temperature of 80 ° C. to dissolve dextrin. To this solution, 148 g of 3-chloro-2-hydroxypropyltrimethylammonium chloride (pure content 65% by mass) (manufactured by Yokkaichi Synthesis Co., Ltd.) was added as a cationizing agent. While stirring this solution, a 5% aqueous solution of sodium hydroxide was further added until the pH in the system reached 11.0 to 12.0, and the reaction was carried out for 8 hours to obtain cationized dextrin CD5.

[Production Example 6] Production of cationized dextrin 500 g of roasted dextrin (British gum, Hydex 208, manufactured by Nippon Corn Starch Co., Ltd.) and 750 g of tap water were charged into a 2 L reaction flask to prepare a dextrin suspension. . Next, this suspension was heated to an internal temperature of 80 ° C. to dissolve dextrin. To this solution, 108 g of glycidyltrimethylammonium chloride similar to Production Example 1 was added as a cationizing agent. While stirring this solution, a 5% aqueous sodium hydroxide solution was further added until the pH in the system reached 11.0 to 12.0, and the reaction was performed for 5 hours to obtain cationized dextrin CD6.

[ Reference Production Example 1 ] Production of cationized dextrin 500 g of dextrin (acid-treated dextrin, Eclipse C, manufactured by Nippon Corn Starch Co., Ltd.) and 750 g of tap water were charged into a 2 L reaction flask to prepare a dextrin suspension. . Next, this suspension was heated to an internal temperature of 80 ° C. to dissolve dextrin. To this solution, 296 g of 3-chloro-2-hydroxypropyltrimethylammonium chloride similar to Production Example 5 was added as a cationizing agent. While stirring this solution, a 5% aqueous sodium hydroxide solution was further added until the pH in the system reached 11.0 to 12.0, and the reaction was carried out for 8 hours to obtain cationized dextrin CD7.

[ Reference Production Example 2 ] Production of cationized dextrin 500 g of dextrin (acid-treated dextrin, Eclipse C, manufactured by Nippon Corn Starch Co., Ltd.) and 750 g of tap water were charged into a 2 L reaction flask to prepare a dextrin suspension. . Next, this suspension was heated to an internal temperature of 80 ° C. to dissolve dextrin. To this solution, 410 g of glycidyltrimethylammonium chloride similar to Production Example 1 was added as a cationizing agent. While stirring this solution, a 5% aqueous sodium hydroxide solution was further added until the pH in the system reached 11.0 to 12.0, and the reaction was performed for 8 hours to obtain cationized dextrin CD8.

[Comparative Production Example 1] Production of cationized starch 500 g of tapioca starch (manufactured by TDC Co., Ltd.) and 750 g of tap water were put into a 2 L reaction flask to prepare a starch suspension. Next, 32 g of glycidyltrimethylammonium chloride similar to Production Example 1 as a cationizing agent and 25 g of anhydrous sodium sulfate (manufactured by Tosoh Corporation) as a swelling inhibitor were added. While stirring this suspension, a 5% aqueous sodium hydroxide solution was further added until the pH in the system reached 11.0 to 12.0, and the reaction was performed for 16 hours to obtain cationized starch CS1.
This cationized starch is commercially available as a paper strength enhancing grade (TAPLINK-3, manufactured by Nippon Corn Starch Co., Ltd.).

[Comparative Production Examples 2 and 3] Production of cationized starch 500 g of corn starch (manufactured by Nippon Corn Starch Co., Ltd.), 500 g of tap water, and 250 g of methanol (manufactured by Shoei Chemical Co., Ltd.) were charged into a 2 L reaction flask, and starch was added. A suspension was prepared. Next, 139 g of glycidyltrimethylammonium chloride similar to Production Example 1 was added as a cationizing agent in Comparative Production Example 2 and 125 g in Comparative Production Example 3. While stirring this suspension, a 5% sodium hydroxide aqueous solution was further added until the pH in the system reached 11.0 to 12.0, and the reaction was carried out for 16 hours to obtain cationized starches CS2 and CS3.

[Comparative Production Example 4] Production of cationized starch 500 g tapioca starch (manufactured by TDC Co., Ltd.), 500 g tap water and 250 g methanol were charged into a 2 L reaction flask to prepare a starch suspension. Next, 32 g of glycidyltrimethylammonium chloride similar to Production Example 1 was added as a cationizing agent. While stirring this suspension, a 5% aqueous sodium hydroxide solution was further added until the pH in the system reached 11.0 to 12.0, and the reaction was performed for 16 hours to obtain cationized starch CS4.

For the cationized dextrins CD1 to CD8 and the cationized starches CS1 to CS4 obtained in the above production examples , reference production examples and comparative production examples, the number average molecular weight and the degree of cationization (nitrogen content) were measured by the following methods. The results are shown in Table 1.
[1] Sample treatment Activated carbon (activated carbon (powder), manufactured by Kanto Chemical Co., Inc.) (25 g) is added to 50 mL of each paste solution (CD1 to CD8, CS1 to CS4) prepared above, and lightly stirred for 2 hours. Processed. After the treatment, the activated carbon and the paste were separated by filtration, and 250 g of ethanol (manufactured by Akanba Chemical Industry Co., Ltd.) was gradually added to the filtrate to cause alcohol precipitation. The precipitate was filtered and the residue was dried to obtain a sample for measuring the molecular weight and measuring the degree of cationization.

[2] Measurement of number average molecular weight Each sample was added to 7 mL of DMSO (containing 0.03 mol / L LiBr) and gelatinized at 90 ° C. for 15 minutes. Each obtained paste was passed through a 0.45 μm membrane filter and then subjected to GPC. The GPC measurement conditions are shown below.
<GPC measurement conditions>
GPC device: HLC-8120GPC (manufactured by Tosoh Corporation)
Column: Two Tosoh SUPER AWM-H (manufactured by Tosoh Corporation), guard column SUPER AW-H (manufactured by Tosoh Corporation)
Moving layer: DMSO (containing 0.03 mol / L LiBr)
Flow rate: Sample side 500 μL / min, Reference side 300 μL / min Temperature: 40 ° C.
Detector: Differential refractometer

[3] Measurement of degree of cationization The nitrogen content of each sample was measured using the semi-micro Kjeldahl method.

[Examples 1 to 6, Reference Examples 1 and 2, and Comparative Examples 1 to 4]
Recycled paper (Canon EN-500; waste paper content: 70% by mass) was cut into a size of 4 cm × 4 cm, and then put into a pulp disaggregator (manufactured by Kumagaya Riki Kogyo Co., Ltd.). Subsequently, 1.0% by mass of sodium hydroxide (manufactured by Kanto Chemical Co., Inc.) is added to the mass of the raw paper, and warm water is added so that the pulp concentration is 6% by mass, and the disaggregation treatment is performed at 45 ° C. for 10 minutes. Went.
Water was added to the pulp slurry after the disaggregation treatment, and the pulp concentration was diluted to 1% by mass to obtain a pulp dispersion. The pulp dispersion is filled with filler (talc: light calcium carbonate = 1: 1, manufactured by Kanto Chemical Co., Inc.), 25% by mass of pulp, and previously prepared CD1-CD8 and CS1-CS4 (additives for paper). 1.7% by mass of pulp, 2% by mass of sulfuric acid band (aluminum sulfate, manufactured by Kanto Chemical Co., Ltd.), 0.3% by mass of sizing agent (Colopearl EV-45S, manufactured by Nippon PMC Co., Ltd.) And 0.03% by mass of a yield improver (colloidal silica, manufactured by Nissan Eka Co., Ltd.) with respect to pulp was added and stirred at room temperature for 15 minutes. In addition, CD1-CD8 and CS1-CS4 were added as 1 mass% aqueous solution.
Next, the paper sheet after paper making was weighed so that the basis weight would be 80 g / m ^2, and a pulp sheet was prepared with a tappy sheet machine (manufactured by Kumagaya Rikyu Kogyo Co., Ltd.).

[Comparative Example 5]
A pulp sheet was obtained in the same manner as in Example 1 except that no paper additive was added.

The pulp sheets of the Examples , Reference Examples and Comparative Examples obtained as described above were pressed for 2 minutes (pressure 3.5 MPa), air-dried for 2 hours, and then constant temperature and humidity (20 ° C., humidity 50%). A humidity control sheet was prepared by leaving it for one day under these conditions, and the paper thickness increasing property, tensile strength index, and size property index were measured and evaluated by the following methods. The results are shown in Table 2.

[1] Paper thickness increasing property The mass (g), area (cm ² ), and thickness (μm) of each humidity control sheet were measured, and the tension (g / cm ³ ) was obtained by calculation. The average value of 5 times was used for each sheet. Note that the smaller the absolute value of the tension, the higher the effect of increasing the paper thickness. The thickness was measured by a method based on JIS P 8118 (Testing method for thickness and density of paper and paperboard).
The paper thickness increasing property was calculated from the following formula using the blank (Comparative Example 5 = 100%) as a reference.
Increase in paper thickness (%) = 100+ (B−A) / B × 100
A: Tension of the sheet to which the paper additive was added B: Tension of the sheet of the blank (Comparative Example 5)

[2] Tensile strength index About each humidity control sheet, the tensile strength (load at the time of fracture | rupture) was measured by the method based on JISP8118. The tensile strength was an average value of 5 times per sheet.
Based on the obtained tensile strength, the tensile strength index was obtained from the following formula using the blank (Comparative Example 5 = 100%) as a reference.
Tensile strength index (%) = C / D × 100
C: Tensile strength of sheet added with paper additive D: Tensile strength of blank (Comparative Example 5) sheet

[3] Size property index For each humidity control sheet, the water absorption was measured by the Krem method in accordance with JIS P 8141. The average value of water absorption was 3 times per sheet.
The sizing degree was the reciprocal of the water absorption degree, and the sizing index was obtained from the following formula using the blank (Comparative Example 5 = 100%) as a reference.
Size index (%) = (E / F) ⁻¹ × 100
E: Water absorption height of sheet added with paper additive F: Water absorption height of blank (Comparative Example 5) sheet

As shown in Table 2, the pulp sheet of each example obtained using a paper additive comprising a cationized dextrin has both a paper thickness increasing effect and a paper strength increasing effect as compared with the comparative example. You can see that it is being demonstrated.

Claims (2)

A paper thickness increasing and paper strength enhancing agent comprising a water-soluble cationized roasted dextrin having a nitrogen content of 0.5 to 4.0% by mass and a number average molecular weight of 500 to 8000. 2. The paper thickness increasing and paper strength enhancing agent according to claim 1 , wherein the nitrogen content is 0.8 to 3.0% by mass .