JP5315499B2 - Cationized tapioca starch, recycled paper and method for producing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an additive which can improve the strength of reclaimed paper without complicating a paper-making system and without worsening operability, even when used for paper materials containing waste paper pulp. <P>SOLUTION: Provided is cationized tapioca starch added to a waste pulp-containing pulp slurry or a paper material slurry and used for producing reclaimed paper, characterized by having a cation substitution degree of 0.048 to 0.207 and a specific electric charge of 300 to 850 meq/g in a gelatinized state. The reclaimed paper containing the same and the method for producing the same are also provided. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to a special cationized tapioca starch for the production of recycled paper added to a paper stock containing waste paper pulp, a recycled paper containing such a special cationized tapioca starch, and a method for producing the recycled paper.

  Usually, when paper is produced, a paper strength enhancer is added to a paper material used as a raw material of paper. Conventionally, polyacrylamide and inorganic particles have been used as paper strength enhancers, but various starches must be added to the paper stock to produce not only strength but also excellent drainage and yield. Is increasing. Among starches, amphoteric starch has attracted attention as a paper strength enhancer that can be applied to various paper stocks, but with the increase in recycling orientation, the demand for used paper pulp as a raw material for recycled paper and recycled paper is increasing. Waste paper contains a large amount of anionic contaminants, and a method of adding cationized starch is known to block the anionic contaminants.

  Patent Documents 1 and 2 disclose a technique for manufacturing paper by adding cationic potato starch, cationic corn starch, or the like. Patent Document 3 describes that cationic wheat starch and cationic corn starch are mixed with cationic potato starch and these mixtures are used as a papermaking raw material. However, when the cationized starch disclosed in these documents is blended with a stock that is a recycled paper raw material, a recycled paper with insufficient strength and drainage may be obtained. It cannot be manufactured efficiently.

  As an example of another cationized starch, Patent Document 4 discloses a technique in which a blend of a cationized tapioca starch having a large molecular weight and colloidal anionic silicic acid or polyacrylamide is used as an additive for papermaking. Patent Document 5 describes that the strength of used paper is increased by adding cationized tapioca starch to recycled paper raw material and controlling the zeta potential of the paper stock to a suitable value (−5 to 0 mv). Yes. However, even when the cationized tapioca starch described in the document is added to the raw material of recycled paper, there is a case where used paper with insufficient strength is obtained. In recent years, as a demand for recycled paper, it has been desired to have sufficient strength.

  As cationized starch to be added to recycled paper, starch having a particularly high degree of cationization (DS) tends to be desired. Waste paper pulp, which is a recycled paper raw material, contains a large amount of anionic contaminants, and these anionic contaminants react with cationic groups. Therefore, when a cationized starch having a low DS is added, the waste paper pulp and the cationized starch are not bonded. If the cationized starch does not act as a binder, high strength recycled paper cannot be obtained.

  In order to increase the strength of recycled paper, cationized starch should be strongly bonded to waste paper pulp. To that end, it is expected to increase the amount of cationized starch or to increase the DS of cationized starch. Is done. However, when producing recycled paper from paper stock on a paper machine, if the blended amount of cationized starch is too high, problems such as poor drainage and poor drying of the stock may occur, and DS is too high. When a modified starch is added, the cation is excessive in a small amount, which may cause problems such as paper strength, yield, and deterioration of drainage.

  Thus, at present, there is a demand for an additive capable of improving the strength of recycled paper without complicating the papermaking system and deteriorating operability even when using a paper stock containing waste paper pulp. It has been.

Special table 2007-516308 gazette Japanese Patent Laid-Open No. 10-131082 Japanese Unexamined Patent Publication No. 60-110998 Japanese Unexamined Patent Publication No. 63-28998 Japanese Patent Laid-Open No. 8-198901

  The present invention has been made to solve the above-mentioned problems, and when producing recycled paper, the drainage of the paper stock is good, the yield is excellent, and the strength of the obtained recycled paper can be increased. It provides a possible additive.

  As a result of intensive studies, the present inventors have added a cationized tapioca starch having a cation substitution degree (DS) and a specific charge amount within a specific range to a stock slurry containing waste paper pulp as a recycled paper raw material. When added, the drainage of the stock was improved, and it was found that a recycled paper having high yield and high strength was obtained, and the present invention was completed.

That is, the first aspect of the present invention is a cationized tapioca starch for the production of recycled paper, which is added to a pulp slurry or paper stock slurry containing waste paper pulp, and the degree of cation substitution (DS) is 0.048 to They are 0.207, in which specific charge amount in the gelatinization conditions to provide a cationic tapioca starch is 300~850 μ eq / g.

In the cationized tapioca starch for producing recycled paper according to the first aspect of the present invention, the DS is 0.048 to 0.207 in the pulp slurry or the stock slurry containing the waste paper pulp as the recycled paper raw material. by specific charge amount of gelatinization state is added cationic tapioca starch 300~850 μ eq / g, improves drainage of the stock, as the superior recycled paper strength can high yield Become.

  Examples of the preferred cationized tapioca starch for producing recycled paper according to the first aspect of the present invention include those added to a pulp slurry or a paper stock slurry in a gelatinized state. Since a specific cationized tapioca starch is added in a gelatinized state, the cationized tapioca starch is uniformly mixed with the stock, and the fibers in the stock and the cationized tapioca starch are easily bonded to each other. The strength of recycled paper becomes higher.

  Furthermore, another preferred cationized tapioca starch for the production of recycled paper of the first aspect of the present invention includes those having a nitrogen content of 0.40 to 1.50%, based on the weight of the starch.

A second aspect of the present invention is a cationic degree of substitution (DS) is from 0.048 to 0.207, specific charge amount in the gelatinized state comprises a cationic tapioca starch is 300~850 μ eq / g This is a recycled paper.

  The recycled paper according to the second aspect of the present invention contains the above-mentioned specific cationized tapioca starch, thereby increasing the binding force between the anionic group contained in the waste paper pulp and the cationized tapioca starch, Will be excellent.

In the present invention, a degree of cationic substitution (DS) is from 0.048 to 0.207, specific charge amount in the gelatinization state is 300-850 mu eq / g cationic tapioca starch, including waste paper pulp Added to pulp slurry or paper slurry.

  The used paper in the present invention is paper that has already been made, and the pulp contained in the used paper is commonly called used paper pulp. Waste paper pulp is distinguished from virgin pulp. The cationized tapioca starch is added during the addition to the stock as a paper strength enhancer.

  The cationized tapioca starch for producing recycled paper in the present invention is added to a pulp slurry or paper stock slurry for producing recycled paper containing waste paper pulp in a gelatinized state.

  The cation substitution degree (DS) of the cationized tapioca starch in the present invention is 0.048 to 0.207, preferably 0.055 to 0.130. When DS is less than 0.048, anionic contaminants contained in the used paper are difficult to bind to the cationized tapioca starch, so that the strength of the obtained recycled paper is lowered. On the other hand, when DS exceeds 0.207, the cationic groups become excessive, the drainage of the paper stock decreases, the yield of recycled paper deteriorates, and the strength of recycled paper becomes insufficient.

  As used herein, the term “degree of cationic substitution (DS)” means the average number of sites or cationic substituents substituted with cationic groups per anhydroglucose unit of the starch molecule. Such DS is calculated by measuring the amount of nitrogen by the Kjeldahl method.

  Examples of the cationic group introduced into the tapioca starch molecule in order to obtain the cationized tapioca starch of the present invention include a primary amino group, a secondary amino group, a tertiary amino group, and a quaternary ammonium group. , Sulfonium group, phosphonium group and the like, and these may be used alone or in combination of two or more.

  Examples of the cationization method for introducing the cation group include a method of using a cationizing agent containing a tertiary amino group or a quaternary ammonium group. The cationization can be performed by, for example, a wet method or a dry method. It can be implemented by law or the like. Specific examples of the cationizing agent include diethylaminoethyl chloride, 3-chloro-2-hydroxypropyltrimethylammonium chloride, 2,3-epoxypropyltrimethylammonium chloride, etc., depending on the cationic group to be introduced. It can be used alone or in combination of two or more.

Cationic tapioca starch in the present invention, when the gelatinized state, the specific charge amount is 300-850 mu eq / g, particularly preferably 350~600 μ eq / g. When the specific charge amount is less than 300 mu eq / g, the cationic groups of the starch reacts with the anionic contaminants from waste paper pulp, it becomes difficult to react with the anionic groups of the used paper pulp. Further, when the specific charge amount exceeds the 850 mu eq / g, the papermaking system adversely affects tends strength development and workability becomes excessive cations.

In this specification, the specific charge amount, using a Mutek Co. streaming potential measuring device PCD-02, the amount of anionic agent required to neutralize the cationic charge as fine particles to the isoelectric point μ It means the amount of charge converted to eq / g.

  The gelatinized state in the present invention means that the cationized tapioca starch is in a paste form, and it can be confirmed, for example, by visual observation that the cationized tapioca starch is in a paste form. The cationized tapioca starch can be heated to a gelatinized state, and the temperature at which gelatinization starts is called the gelatinization start temperature. The gelatinization treatment of the cationized tapioca starch can be carried out by gelatinization at 90 to 130 ° C. for a desired time, usually using a jet-cooker or a batch-type cooker.

  The cationized tapioca starch preferably has a nitrogen content of 0.40 to 1.50%, particularly preferably 0.50 to 1.10%, based on the weight of the cationized tapioca starch. The nitrogen content is usually measured by the Kjeldahl method. If the nitrogen content is less than 0.40%, the positive charge power of the cationized tapioca starch will be small, the cohesive force in the stock will be reduced, and the paper machine will be less maneuverable, and the final product will be recycled paper. The strength of will become low. On the other hand, if the nitrogen content is higher than 1.50%, the charge balance in the papermaking system is lost, the interfiber bonding force (internal bond) of the paper derived from starch is insufficient, and the strength of the recycled paper is reduced. .

  As the cationized tapioca starch for the production of recycled paper in the present invention, those having a viscosity of 15.0 to 20.0 cps when measured at 40 ° C. with a 2% by weight aqueous solution of such starch are preferable. Thus, since cationized tapioca starch having a gelatinized viscosity (40 ° C., 2% by weight aqueous solution) of 15.0 to 20.0 cps is added, it is more evenly mixed with the paper stock and further excellent in strength. Recycled paper can be obtained.

  In the present specification, the viscosity of the cationized tapioca starch is obtained by dissolving the cationized tapioca starch completely in water to prepare an aqueous solution having a concentration of 2% by weight, and measuring the aqueous solution with a B-type viscometer at 40 ° C. Means the value. The spindle number in the viscosity measurement is # 2, and the spindle rotational force is 60 rpm.

Recycled paper of the present invention is a cationic degree of substitution (DS) is from 0.048 to 0.207, that specific charge amount in the gelatinized state comprises a cationic tapioca starch is 300~850 μ eq / g It is a characteristic, and by containing the specific cationized tapioca starch, the binding force between the anionic group contained in the waste paper pulp and the cationized tapioca starch becomes strong, and the strength becomes excellent.

  The recycled paper in this specification means paper obtained by reusing used paper. That is, recycled paper contains not only virgin pulp as a raw material but also used paper as a required component. Specific examples of waste paper include newspaper waste paper, magazine waste paper, cardboard waste paper, and OA paper waste paper.

  The recycled paper of the present invention is produced from waste paper, but contains the above-mentioned cationized tapioca starch as a required component, and can further contain virgin pulp, fillers, and various drugs. As the virgin pulp, any of pulp (N material) obtained from conifers such as Douglas fir, radiata pine, cedar and the like (L material) obtained from broad-leaved trees such as eucalyptus and oak may be used. Waste paper is paper that has already been made, and pulp contained in waste paper is commonly called waste paper pulp. In the present specification, a distinction is made between waste paper pulp and virgin pulp.

The method for producing recycled paper of the present invention is a method for producing recycled paper using a stock containing waste paper pulp, and the degree of cation substitution (DS) is 0.00 on the pulp slurry or stock slurry containing waste paper pulp. is from 048 to 0.207, can be mentioned those characterized by adding a specific charge amount of gelatinization state is 300~850 μ eq / g cationic tapioca starch in gelatinized condition, so By adding a specific cationized tapioca starch in a gelatinized state, the drainage of the stock is improved, and it becomes possible to produce recycled paper having excellent strength with a high yield.

  The above cationized tapioca starch is added to the pulp slurry or stock slurry as a paper strength enhancer, but it may be mixed with waste paper and virgin pulp, or the waste paper and virgin pulp may be mixed first, and then It can be added.

  Before adding the cationized tapioca starch to the paper slurry, the aluminum compound is added to the pulp slurry, or after adding the cationized tapioca starch to the pulp slurry, the aluminum compound is added to form a paper slurry. preferable. Further, an aluminum compound may be mixed with the above cationized tapioca starch and added to the pulp slurry. The cationized tapioca starch may be added to the paper slurry before or after the addition of the aluminum compound, or together with the aluminum compound.

  A water-soluble aluminum compound can be used as the aluminum compound. Examples of the aluminum compound include polyaluminum chloride, alumina sol, polyaluminum sulfate, polyaluminum sulfate silicate, aluminum chloride, and aluminum sulfate. These aluminum compounds may be used alone or in combination of two or more. Among these, aluminum sulfate is particularly preferable.

  Paper stock slurries typically contain fillers as well as pulp. The filler is not particularly limited, but as with ordinary paper, clay, talc, kaolin, white carbon, calcium silicate, zinc oxide, magnesium oxide, light / heavy calcium carbonate, titanium dioxide, One or several kinds of aluminum oxide can be appropriately selected and used.

  Other additives contained in the paper slurry include inorganic conductive agents such as sodium chloride and potassium chloride; organic conductive agents such as cationic polymers and sulfonated styrene resins; pigments such as titanium dioxide; calcium carbonate, kaolin, clay, Organic pigments, dimensional stabilizers, surfactants, bulking agents, and dyes can be added.

  The method for producing recycled paper of the present invention can include usually used processes, that is, a pulp production process, a preparation process, and a papermaking process. The pulp manufacturing process is a process for obtaining a pulp slurry, which is usually an aqueous slurry, by subjecting the raw material to mechanical or chemical treatment. In the preparation process, the pulp slurry thus obtained is beaten, and chemicals are further blended depending on the use of the paper, etc., and the basic properties to the final paper are imparted to the paper slurry. It is a process for preparing. The paper making process is a process of making a paper slurry from the preparation process in a paper machine.

  In the method for producing the recycled paper, the cationized tapioca starch is added to the pulp slurry or the stock slurry before or during the preparation step, usually immediately before the preparation step. . Prior to adding the cationized tapioca starch into the pulp slurry or stock slurry, the cationized tapioca starch is adjusted to its gelatinized state in advance.

  The paper stock slurry is a slurry in which a paper additive is internally added to a pulp slurry, and is generally used to produce a sheet, a web-like product, for example, a product containing cellulose fibers such as a pulp sheet and paper. An aqueous dispersion that can be obtained. In this specification, a pulp slurry means a mixed slurry of pulp (waste paper pulp and / or virgin pulp) and a filler such as charcoal cal.

  The addition amount of the cationized tapioca starch of the present invention in a steamed and gelatinized state to the pulp slurry or paper slurry is different depending on the composition of the pulp slurry or paper slurry, and it is difficult to say in general. However, 0.1 to 2.0 parts by weight of cationized tapioca starch is preferably added to 100 parts by weight of the pulp slurry or paper slurry, and more preferably 0.1 to 1.5 parts by weight of cation. The amount of added tapioca starch is preferable, and the amount of added cationized tapioca starch of 0.2 to 1.3 parts by weight is particularly preferable.

  In the method for producing recycled paper of the present invention, when the cationized tapioca starch in the gelatinized state is added to a pulp slurry or a stock slurry, the cationized tapioca starch reacts with the pulp and filler in the slurry. When both react, the zeta potential after starch addition will change greatly compared to before starch addition. A large change in the zeta potential means that the reactivity between the cationized tapioca starch according to the present invention and the pulp slurry or paper slurry is large.

  When 0.25 parts by weight of the cationized tapioca starch is added to the pulp slurry or the paper slurry 100 parts by weight of the cationized tapioca starch, the change in zeta potential is determined by the composition of the slurry. Although it changes depending on the case, it is about 11 to 15 mV. Moreover, when 0.5 parts by weight of the cationized tapioca starch is added to the pulp slurry or the paper slurry 100 parts by weight based on the weight of the cationized tapioca starch, the change in zeta potential is Although it varies depending on the composition, it is about 20 to 30 mV. Furthermore, when the addition amount of cationized tapioca starch is 1.0 part by weight, the change value of the zeta potential is about 35 to 50 mV.

  When the specific cationized tapioca starch in the present invention is compared with potato starch or corn starch having the same degree of cationization, it is better to add the cationized tapioca starch of the present invention to the pulp slurry or paper slurry. The change is large. Therefore, it is considered that the cationized tapioca starch of the present invention is superior in pulp reactivity in pulp slurry or paper slurry than potato starch and corn starch having the same degree of cationization.

  Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to the following examples.

As the adjusted pulp of the pulp slurry , softwood kraft pulp (NBKP), hardwood kraft pulp (LBKP), waste paper pulp mainly composed of newspapers / miscellaneous paper (DIP) was used, and these pulps were mixed. Water was added to this mixture, and CaCO ₃ was added as a filler to obtain a pulp slurry having a solid content of about 0.8% by weight. The composition (weight) ratio in the slurry was NBKP: LBKP: DIP: filler = 10: 30: 45: 15 in terms of solid content. When the zeta potential of the pulp slurry was measured with a zeta electrometer (SZP-06 manufactured by Mutek), it was -37 mV.

Preparation of cationized starch In Examples and Comparative Examples described later, various cationized starches as shown in Table 1 below were prepared as cationized starches to be added to a pulp slurry containing waste paper pulp.

  Sample A as the cationized starch of the present invention was obtained in the following steps. That is, 6 kg of tapioca starch (water content: 13%) was placed in a stirrer with a squeezed shovel, sprayed with 500 g of caustic soda aqueous solution (concentration 50 wt%) under stirring (rotation speed 150 rpm), and quaternized as a cationizing agent After spraying 600 g of an aqueous solution of ammonium salt (product name Quat 188 manufactured by Dow Chemical Co., Ltd., concentration 69 wt%) and stirring for 3 minutes, the sample was dried for 5 hours in a dryer at 50 ° C. Manufactured.

  Sample B as the cationized starch of the present invention is sprayed with 500 g of caustic soda, 1,200 g of the quaternary ammonium salt, and stirred for 3 minutes and then dried at 50 ° C. for 5 hours. It was obtained by letting.

  As the tapioca starch A as a cationized starch for the comparative example, the product name CATO308 manufactured by Nippon SC Co., Ltd. was used. As corn starch A, product name Almidon XP HS 60 manufactured by IMSA was used, and as corn starch B, product name Almidon XP HS 100 manufactured by IMSA was used. Potato A was obtained by cationizing potato starch (water content 18%) in the same manner as Sample A described above. Potato B was obtained by cationizing potato starch (water 18%) in the same manner as Sample B.

  The viscosities in Table 1 were measured with a B-type viscometer (spindle number # 2, rotation 60 rpm) after preparing a 2% by weight aqueous solution of each starch, heating the adjusted solution gently at 40 ° C.

Regarding the charge amount in Table 1, the anion requirement amount was measured with a PCD apparatus (manufactured by Mutek). This is the amount of anionic drug that requires a cationic charge such as fine particles before the isoelectric point (neutralization). A starch solution having a concentration of 1% by weight of each starch (specific gravity = 1) was applied to a PCD apparatus and titrated with 0.001N PVSK (polyvinyl potassium sulfate). This was converted to a solid content to obtain a specific charge amount. When the titration value of 0.001N PVSK is X mL, the specific charge amount can be obtained by the following calculation.
0.001N PVSK (specific gravity = 1) Titration volume (mL): X
Measured starch solid content (g) = 10 (mL) × 1 (%) × 1 (specific gravity)
= 10 x 0.01 x 1
= 0.1 (g)
Therefore, specific charge amount = 10 ⁻³ X (L ) × 0.001 (eq / L) ÷ 0.1 (g)
= 10 ⁻⁶ X ( eq) /0.1 (g)
= 10X ( μ eq / g)

  Each stock slurry containing waste paper pulp and cationized starch was prepared by adjusting the addition amount of cationized starch to 2.5 g with respect to 1 kg of pulp slurry and changing the kind of cationized starch described in Table 1. Details are described below.

Example 1
5 g of aluminum sulfate (sulfuric acid band) is added to 1 kg of the pulp slurry prepared as described above, and then 2.5 g of sample A shown in Table 1 corresponding to the cationized tapioca starch of the present invention is heated at 120 ° C. Add sample A in the gelatinized state and in the gelatinized state, and add 5 g of Akyleketene dimer AKD (size agent AD1602 manufactured by Seiko PMC), and add a retention agent (Percoll 182 manufactured by Ciba). They were added so that the concentration was 100 ppm, and these blends were used as the sample A paper slurry.

Example 2
As an alternative to sample A, sample B shown in Table 1 corresponding to the cationized tapioca starch of the present invention was used, and other conditions were the same as in Example 1, and a paper slurry containing waste paper pulp and sample B was prepared. did.

Comparative Example 1
A stock slurry containing waste paper pulp and tapioca starch A was prepared under the same conditions as in Example 1 except that tapioca starch A shown in Table 1 was used as an alternative to sample A.

Comparative Example 2
As a substitute for sample A, corn starch A shown in Table 1 was used, and the other conditions were the same as in Example 1. A paper slurry containing waste paper pulp and corn starch A was prepared.

Comparative Example 3
A corn starch B described in Table 1 was used as an alternative to sample A, and a paper slurry containing waste paper pulp and corn starch B was prepared under the same conditions as in Example 1 for the other conditions.

Comparative Example 4
A stock slurry containing waste paper pulp and potato A was prepared under the same conditions as in Example 1 except that potato A shown in Table 1 was used as an alternative to sample A.

Comparative Example 5
A stock slurry containing waste paper pulp and potato B was prepared under the same conditions as in Example 1 except that potato B shown in Table 1 was used as an alternative to sample A.

  Next, the amount of the cationized starch added was adjusted to 5.0 g with respect to 1 kg of the pulp slurry, and each stock slurry containing waste paper pulp and cationized starch was prepared by changing the type of cationized starch described in Table 1. . Details are described below.

Example 3
A stock slurry containing waste paper pulp and cationized tapioca starch sample A was prepared under the same conditions as in Example 1 except that the amount of Sample A listed in Table 1 was 5.0 g.

Example 4
As an alternative to Sample A, Sample B shown in Table 1 corresponding to the cationized tapioca starch of the present invention was used, and the other conditions were the same as in Example 3, and paper containing waste paper pulp and cationized tapioca starch sample B A slurry was prepared.

Comparative Example 6
A stock slurry containing waste paper pulp and tapioca starch A was prepared under the same conditions as in Example 3 except that tapioca starch A shown in Table 1 was used as an alternative to sample A.

Comparative Example 7
As a substitute for sample A, corn starch A shown in Table 1 was used, and the other conditions were the same as in Example 3. A paper slurry containing waste paper pulp and corn starch A was prepared.

Comparative Example 8
As a substitute for sample A, corn starch B shown in Table 1 was used, and the other conditions were the same as in Example 3, and a paper slurry containing waste paper pulp and corn starch B was prepared.

Comparative Example 9
A stock slurry containing waste paper pulp and potato A was prepared under the same conditions as in Example 3 except that potato A shown in Table 1 was used as an alternative to sample A.

Comparative Example 10
A stock slurry containing waste paper pulp and potato B was prepared under the same conditions as in Example 3 except that potato B shown in Table 1 was used as an alternative to sample A.

  Next, the amount of cationized starch added was adjusted to 10.0 g with respect to 1 kg of pulp slurry, and each paper stock slurry containing waste paper pulp and cationized starch was prepared by changing the type of cationized starch described in Table 1. . Details are described below.

Example 5
A stock slurry containing waste paper pulp and cationized tapioca starch sample A was prepared under the same conditions as in Example 1 except that the amount of Sample A listed in Table 1 was 10.0 g.

Example 6
As an alternative to sample A, the sample B shown in Table 1 corresponding to the cationized tapioca starch of the present invention was used, and the other conditions were the same as in Example 5, and the paper containing waste paper pulp and cationized tapioca starch sample B was used. A slurry was prepared.

Comparative Example 11
A stock slurry containing waste paper pulp and tapioca starch A was prepared under the same conditions as in Example 5 except that tapioca starch A shown in Table 1 was used as an alternative to sample A.

Comparative Example 12
As a substitute for sample A, corn starch A shown in Table 1 was used, and the other conditions were the same as in Example 5. A paper slurry containing waste paper pulp and corn starch A was prepared.

Comparative Example 13
As a substitute for sample A, corn starch B shown in Table 1 was used, and the other conditions were the same as in Example 5, and a paper slurry containing waste paper pulp and corn starch B was prepared.

Comparative Example 14
A stock slurry containing waste paper pulp and potato A was prepared under the same conditions as in Example 5 except that potato A shown in Table 1 was used as an alternative to sample A.

Comparative Example 15
A stock slurry containing waste paper pulp and potato B was prepared under the same conditions as in Example 5 except that potato B shown in Table 1 was used as an alternative to sample A.

Paper Slurry Evaluation Test (1) Evaluation of reactivity with pulp as seen from zeta potential Zeta potential indicates the strength of the charge, and is an indicator of the magnitude of the charge and the distance to the isoelectric point (particles, fibers Etc.). Zeta potential (-37 mV) of pulp slurry to which no chemical is added, zeta potential (-34 mV) of stock slurry to which chemical is added to this pulp slurry and starch is not added, and zeta of stock slurry after starch is added The potential was measured with a zeta potentiometer (trade name Mutek SZP-06, manufactured by BTG), and the zeta potential before adding starch (-34 mV) and the zeta potential after adding starch were compared. The obtained results are shown in Tables 2 to 4. As can be seen there, it is considered that the greater the change in zeta potential, the higher the reactivity between the starch and the paper slurry. Although these evaluation criteria are described in Tables 2 to 4, when the amount of cationized starch added is large, the value of change in zeta potential increases as a whole due to accumulation in the circulation operation. The evaluation standard suitable for the amount of addition was set.

(2) Evaluation of internal bond strength The handsheet was obtained by using a sheet machine HAAGE-Sheet Former manufactured by ERNST HAAGE, type BBS (with Siemens PLC controller) and applying a pressure of 800 mbar with a sheet press. Was dried with a rotary dryer (93 ° C. ± 4) for 2 minutes to obtain a handmade paper corresponding to 80 g / m ² . Japan TAPPI paper pulp test method No. 1 using an internal bond strength measuring apparatus (trade name TS-25000AW-9, manufactured by Precision Scientific Inc). 18-2: 2000 paper and paperboard-Internal bond strength test method-Part 2: The strength of the above-mentioned handmade paper was measured using the internal bond tester method. The obtained results are listed in Tables 2 to 4 together with their evaluation criteria. If the degree of cationization of the cationized starch is too high, it is expected that the actual papermaking system will circulate and the cation will become excessive and the strength such as internal bonds will be difficult to develop.

(3) Evaluation of reactivity with pulp from the viewpoint of drainage The drainage of paper stock is specified by JIS P 8121 after the stock slurry of 0.3% concentration is agitated in the same procedure as the above pulp slurry. It was measured using a method using a canedian freeness tester, which is a method of measuring “freeness” indicating the degree of drainage of the pulp being used. The obtained results are listed in Tables 2 to 4 together with their evaluation criteria.

(4) Yield evaluation Total yield and ash yield were measured with a Brit jar tester. The above-mentioned stock slurry is prepared to a concentration of 0.58%, stirred at a stirring speed of 1,300 rpm and a wire 200 mesh for 60 seconds, the initial 5 second filtrate is discarded, and then the 15-second filtrate is collected to obtain a solid content. The yield was determined by measuring About ash content, the stock slurry was processed at 525 degreeC for 1 hour using the ashing apparatus (CEM company make, brand name: MAS7000), and the ash content of each stock slurry was measured. The yield result was obtained by the following formula. The obtained results are listed in Tables 2 to 4 together with their evaluation criteria.
Total yield: {1- (filtrate concentration / stock slurry concentration)} × 100
Ash content yield: {1- (ash content of filtrate / ash content of paper slurry)} × 100

  Tables 2 to 4 summarize the experimental data for each added amount of starch.

  As is apparent from the respective tables, with the same addition amount of cationized starch, the paper slurry of the examples is excellent in change in zeta potential, strength, drainage, and yield, and as a recycled paper raw material. Is suitable. On the other hand, the stock slurry of the comparative example has a poor balance of performance and is not preferable as a recycled paper raw material. Therefore, Sample A and Sample B added in the examples proved to be superior additives to other cationized starches. That is, these cationized tapioca starches are useful as additives that can improve the strength of recycled paper without complicating the papermaking system and without deteriorating operability.

Claims (3)

A cationized tapioca starch for the production of recycled paper, which is added to a pulp slurry or paper stock slurry containing waste paper pulp, having a cation substitution degree of 0.048 to 0.207, and a specific charge amount in a gelatinized state characterized in that but is 300~850 μ eq / g, the cationic tapioca starch.   The cationized tapioca starch according to claim 1, which is added to the pulp slurry or paper slurry in a gelatinized state. Degree of cationic substitution is from 0.048 to 0.207, specific charge amount in the gelatinization conditions characterized in that it comprises a cationic tapioca starch is 300~850 μ eq / g, recycled paper.