JP2003227091A - Ampholytic starch decreased in viscosity, method for producing the same, and method for making paper - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide ampholytic starch capable of exhibiting an excellent effect of increasing paper power, even when increase in an amount of the starch to be added is avoided, while keeping filterability and retention, to provide a method for producing the ampholytic starch, and to provide a method for producing paper or board having the increased paper power, by utilizing the ampholytic starch so as to keep the good filterability and retention, and by avoiding the increase in the amount of the starch which conventionally makes stains in a paper-making machine increase and causes a balance in a paper-making system to be lost. <P>SOLUTION: This method for producing the ampholytic starch comprises adding urea and inorganic phosphoric acids to cationic starch into which a tertiary amine and/or a quaternary ammonium salt is introduced to give the cationic starch a degree of cation substitution of 0.01-0.06, so as to form slurry having a pH of ≤5.0 which is measured after the materials are mixed, and then roasting the slurry to make it react at 110-180°C in a dry process to form the ampholytic starch, wherein phosphate groups are introduced into the ampholytic starch, so that the ampholytic starch has a viscosity of 5-500 mPa.s, when measure in a 5% solution of the starch by using a B-type viscometer (60 rpm, at 50°C), and a degree of anion substitution of 0.0005-0.03. The ampholytic starch is produced by the method. The method for producing the paper or the board comprises conducting paper making of pulp slurry to which the ampholytic starch is added. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for producing an amphoteric starch in which urea and phosphoric acid are added to a cationic starch and a roasting reaction is carried out in a dry process to reduce the viscosity simultaneously with phosphorylation. The present invention relates to an amphoteric starch obtained and a method for making a paper by adding the amphoteric starch to a pulp slurry.

[0002]

2. Description of the Related Art In papermaking of paper or paperboard, increasing drainage in the wire part, and filler and fine (fine fibers) in the sheet formed on the wire part as well.
For the purpose of improving the retention of the paper and the paper strength of the paper or board made from paper, adding a paste solution of cationic starch or amphoteric starch to pulp slurry together with internal additives such as sulfuric acid band and sizing agent. Is a conventional technique.

In recent years, the use rate of waste paper pulp in paper and paperboard has increased in recent years due to environmental problems, and the progress of recycling has led to deterioration of the raw material pulp containing waste paper, forcing the reduction of paper strength of paper or paperboard. . Therefore, the amount of cationic starch added as a paper strength agent for improving the strength of paper or paperboard is increased to cope with the problem. However, since such a starch-based paper strength agent does not remain in 100% of the sheet, white water is not used. It flows into the inside of the papermaking system, and in combination with a high degree of closure inside the papermaking system, dirt in the papermaking system increases, resulting in a decrease in productivity and a decrease in operational stability. Therefore, in order to solve such a problem as much as possible, amphoteric starch is used to improve drainage which affects productivity and retention for preventing increase of stains in the papermaking system. This amphoteric starch and its manufacturing method are described in
The method described in JP-A-32081 is known, but the capacity of the amphoteric starch produced by this production method has become unable to cope with the current state of papermaking.
Even if you add more to make up for it, it will hit a ceiling.

Further, Japanese Patent Laid-Open No. 2001-19701 describes an amphoteric starch which is urea-phosphorylated, which is improved in this point and further improves drainage, and which is hard to reach a peak even when added. However, this amphoteric starch has a pH of urea phosphorylation.
Is adjusted to 6.0 to 10.0, and is not subjected to a viscosity reduction treatment. Such an internally added paper strength agent has 100% yield in the sheet as described above. Therefore, it is pointed out that the addition of starch promotes the accumulation in the papermaking system due to the highly closed interior of the papermaking system, increases the stains on the papermaking machine, and causes the balance in the system to be disturbed. Has been done.

[0005]

In view of the above situation, the present invention provides amphoteric starch which exhibits excellent paper-strengthening effect without addition while maintaining drainage and retention. It is intended to provide a manufacturing method. Another purpose is to use this amphoteric starch to increase stains on the paper machine while maintaining good drainage and retention, without adding starch, which may cause imbalance in the system, and to achieve high paper It is to provide a method for making strong paper or paperboard.

[0006]

Means for Solving the Problems As a result of intensive studies to solve the above problems, the present inventors have found that tertiary amine and / or
Alternatively, the cationic starch into which the quaternary ammonium salt has been introduced is subjected to urea phosphoric acid treatment to simultaneously reduce the viscosity (lower the molecular weight) and phosphorylate the starch, thereby adding the starch while maintaining good drainage and retention. The present inventors have found an amphoteric starch excellent in a paper strength enhancing effect capable of making a paper or a paper board having a high paper strength, and a manufacturing method thereof.

That is, the present invention includes the following inventions. (1) In producing an amphoteric starch for papermaking, a cationic starch having a cation substitution degree of 0.01 to 0.06 and a tertiary amine and / or a quaternary ammonium salt introduced thereinto has a slurry pH of 5.0 after mixing. Urea and inorganic phosphoric acid were added as shown below, followed by a dry-type roasting reaction at 110 to 180 ° C. to obtain a 5% viscosity B type viscosity (60 rpm, 50 rpm).
A method for producing an amphoteric starch, characterized in that an amphoteric starch having an anion substitution degree of 0.0005 to 0.03 and a phosphate group introduced thereinto is obtained at a temperature of 5 to 500 mPa · s. (2) The method for producing an amphoteric starch according to (1) above, wherein the inorganic phosphoric acid is at least one selected from the group consisting of orthophosphoric acid and alkali metal salts and alkaline earth metal salts of inorganic phosphoric acids. (3) The method for producing an amphoteric starch according to (2), wherein an inorganic acid and / or an organic acid is added in addition to urea and inorganic phosphoric acid. (4) Amphoteric starch obtained by the production method described in (2) or (3) above. (5) A method for producing paper or paperboard, which comprises making the pulp slurry containing the amphoteric starch described in (4) above into paper.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The raw material starch used in the present invention is not particularly limited, and raw starch such as tapioca starch, corn starch, waxy corn starch, potato starch or wheat starch, and these raw starch are If the hydroxyl group necessary for the cationization and the phosphorylation of acetylation remains, acetylation by a known method,
A chemically modified starch in which a substituent such as hydroxyethylated or hydroxypropylated is introduced, or a starch that has been reduced in viscosity (lower molecular weight) in advance by acid, oxidation, enzyme or the like can be used. Further, these starches can be used in combination of two or more kinds.

The cationization of the raw material starch in the present invention may be carried out by any known technique, and as the cationizing agent, a tertiary amine such as diethylaminoethyl chloride or the like, 3-chloro-2-hydroxypropyltrimethylammonium is used. Quaternary ammonium salts such as chloride and glycidyl trimethyl ammonium chloride are preferably used. For cationization, an alkali metal hydroxide such as sodium hydroxide or potassium hydroxide, or an alkaline earth metal hydroxide such as calcium hydroxide or magnesium hydroxide is usually used.

The degree of cation substitution of cationic starch is 0.01.
It is necessary to be 0.06, preferably 0.0.
It is 2 to 0.06. When the substitution degree is less than 0.01, the effect of the present invention is low, and when it exceeds 0.06, the reaction becomes difficult and the cost increases, which is not practical.

Following the cationization, the viscosity reduction and the phosphoric acid esterification are simultaneously performed by urea phosphoric acid treatment to obtain a low viscosity amphoteric starch. When producing an amphoteric starch, an anionic group must be introduced into the cationic starch, but a phosphoric acid ester group is preferably used in terms of cost and workability. The phosphate ester group can be introduced by adding a phosphate such as sodium tripolyphosphate alone and introducing the phosphate ester group by a roasting reaction, or by adding urea together with the phosphate to produce a phosphate group. There is a method of introducing a phosphoric acid ester group and a carbamic acid ester group (not an anion group) by a baking reaction. On the other hand, in any of the conventional methods, the condition is that the pH after mixing the chemicals is 5.5 to 6.0 or more. This is because it was believed that when the pH was low, the molecular weight was lowered during the roasting reaction and the function of the amphoteric starch was impaired. In fact, amphoteric starch whose molecular weight has been reduced by acid modification (reduction of molecular weight by inorganic or organic acid) or oxidation reduces its function.

In the present invention, inorganic phosphoric acid and urea are combined so that the slurry pH after mixing the chemicals is 5.0 or less, preferably 1.5 to 4.0, and phosphoric esterification is carried out by a roasting reaction. At the same time, by controlling the viscosity to be lowered, it is possible to impart a function which the conventional amphoteric starch does not have.

Examples of the inorganic phosphoric acid used in the present invention include orthophosphoric acid (orthophosphoric acid), pyrophosphoric acid,
Tripolyphosphoric acid, hexametaphosphoric acid, and their alkali metal salts (for example, sodium salt, potassium salt), alkaline earth metal salts (for example, calcium salt, magnesium salt) and ammonium salt, specifically sodium dihydrogen phosphate, Examples thereof include disodium hydrogen phosphate, sodium tripolyphosphate, sodium hexametaphosphate, sodium hydrogen pyrophosphate, and ammonium hydrogen phosphate, and these may be used alone or in combination of two or more.

The addition rate of phosphoric acid and urea to the cationic starch is 0.2 to 5.0% by weight of phosphoric acid per starch solid content,
Urea is preferably 0.5 to 10.0% by weight,
A small amount (usually within 50 mol% relative to phosphoric acids) of other inorganic acids (eg hydrochloric acid, sulfuric acid, nitric acid) and / or organic acids (eg acetic acid, oxalic acid, citric acid, maleic acid) for viscosity control. Can be added, but the condition is that the slurry pH after mixing the chemicals is 5.0 or less. After dissolving phosphoric acid, urea, and a small amount of other acid in water, the cationic starch is uniformly impregnated and mixed. Any known method can be used for impregnating and mixing the chemicals as long as they can be uniformly mixed. After impregnation and mixing, the water content is 15
It is dried to a weight percentage of less, preferably 6 wt% or less, but the drying method is not particularly limited.

After drying, the mixture is put into a roasting reactor 110-180.
The roasting reaction is carried out at ℃ for several minutes to several hours. If the roasting temperature is too low, phosphoric acid esterification will not proceed easily, and if it is too high, a coloring reaction will occur and the commercial value will be reduced. The conditions for the roasting reaction (roasting temperature, roasting time) are appropriately determined depending on the amounts of phosphoric acid, urea, (other acids) added, the type of roasting reactor and the required quality (phosphate ester group amount, viscosity, etc.). To be selected.

The degree of substitution of the phosphoric acid ester group is 0.0005.
Is required to be 0.03, and the molar ratio of the cation group and the anion group (phosphate ester group) is 1: 0.05 to
It is preferably 0.5. If the molar ratio is too small, the function as an amphoteric starch cannot be fulfilled, and if it is too large, the agglomeration between starch molecules becomes too strong, and the function as an amphoteric starch also deteriorates.

The degree of lowering the viscosity (lowering the molecular weight) after the completion of the roasting reaction is 5% with the paste liquid B type viscosity (60 rpm, 50 ° C.) of 5%.
It is necessary to be up to 500 mPa · s, and if it is too low or too high, the excellent paper-strengthening effect which is a feature of the amphoteric starch cannot be exhibited. The above-mentioned 5% viscosity B type viscosity (60 rpm, 50 ° C.) is 5 to 250 mPa.
-S is preferable.

The amphoteric starch is added to the pulp slurry in a gelatinized state, and the gelatinization method is a batch method or a continuous gelatinization method. The type of pulp used and the pH of papermaking are appropriately selected according to the purpose, and other internal additives (sulfuric acid band, sizing agent, filler, other paper-strengthening agent, etc.) can be added as required. The gelatinized amphoteric starch is added to the pulp slurry by a machine chest or a head box like other internal additives, and the addition amount is 0.1 to 2.0.
It is desirable that the content is wt%. The pulp slurry to which the amphoteric starch is added is subjected to papermaking in the same manner as in a general paper or paperboard manufacturing method to obtain a desired paper or paperboard.

[0019]

EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples. Further, in the following Examples and Comparative Examples, parts and%
Is based on weight.

Example 1 100 parts of tapioca starch was dissolved in 150 parts of water and heated to 40.degree. A 3% aqueous sodium hydroxide solution was added to adjust the pH to 11.5, and 3-chloro-2-hydroxypropyltrimethylammonium chloride was added as a quaternary ammonium salt cationizing agent to 5.
After adding 8 parts, the reaction was performed for 16 hours while maintaining the temperature and pH, and the reaction was terminated by adjusting the pH to 6.0. After the reaction is completed, the slurry is dehydrated, washed and dried to have a water content of 1
2% cationic starch was obtained. The amount of nitrogen in the obtained cationic starch was measured by the Kjeldahl method, and the substitution degree of the quaternary ammonium salt was calculated to be 0.04.

Orthophosphoric acid (0.8% starch) and urea (3.0% starch) were dissolved in water (15% starch), and the cationic starch was impregnated and mixed so that the drug solution and the starch were uniform. It was
The slurry pH after mixing was 2.3. Then, after drying to a water content of 5%, the mixture was divided into two and heated at 135 ° C. and 155 ° C. for 30 minutes using a hot air heater to perform a roasting reaction and a phosphoric esterification (anion). At the same time, amphoteric starches A and B having a reduced viscosity were obtained. The obtained amphoteric starch was acidified with hydrochloric acid in water-ethanol 1: 1.
After purification with a liquid, the amount of bound P was measured by the Fiske-Suvaroe method to calculate the degree of substitution of the phosphate ester. The B type viscosity was measured by heating 5% slurry while stirring at 95 ° C for 30 minutes, cooling to 50 ° C, and using a Brookfield viscometer at 60 rpm at the 15th rotation. The analysis results are shown in Table 1.

(Example 2) In the roasting reaction, the amount of starch 15
The cationic starch obtained in Example 1 was obtained by dissolving 0.3% orthophosphoric acid in starch, 0.8% sodium dihydrogenphosphate in starch and 3.0% urea in starch in water. The drug solution and starch were impregnated and mixed so as to be uniform. Slurry p after mixing
H was 2.8. Others obtained amphoteric starches C and D according to the method of Example 1. The analysis results are shown in Table 1.

(Example 3) In the roasting reaction, the amount of starch against starch 15
0.8% starch to normal phosphoric acid, 3.0% starch to urea and 0.02% starch to hydrochloric acid were dissolved in 10% water, and the cationic starch obtained in Example 1 contained a drug solution and starch. The mixture was impregnated and mixed so as to be uniform. The slurry pH after mixing was 2.2. Others obtained amphoteric starches E and F according to the method of Example 1. The analysis results are shown in Table 1.

Example 4 Amphoteric starches G and H were obtained according to the method of Example 1 except that 5.3 parts of diethylaminoethyl chloride hydrochloride as a tertiary amine cationizing agent was added to the starch during the cationization reaction. . The analysis results are shown in Table 1.

(Comparative Example 1) Example in which the viscosity reduction treatment is not carried out In order to compare the performance of the amphoteric starches produced in Examples, an amphoteric starch which has been generally produced conventionally is produced. Sodium tripolyphosphate containing 1.8% of starch was dissolved in water containing 15% of starch, and the pH was adjusted to 7.0 with hydrochloric acid. This chemical solution was uniformly mixed with the cationic starch obtained in Example 1 by impregnation. Then, after drying to a water content of 5%, a roasting reaction is carried out by heating at 145 ° C. for 30 minutes using a hot air heater, without reducing the viscosity, and phosphoric esterification (anionization) An amphoteric starch a that had been subjected only to was obtained. The analysis was performed in the same manner as in Example 1, and the results are shown in Table 1.

(Comparative Example 2) Example in which phosphate and urea are combined but not subjected to viscosity reduction treatment: Water with 15% starch, 0.8% starch with orthophosphoric acid and 3.0% starch. Dissolve the urea in the solution and adjust the pH with sodium hydroxide.
Was adjusted to 7.0. This chemical solution was uniformly mixed with the cationic starch obtained in Example 1 by impregnation. Then, after drying to a water content of 5%, a roasting reaction is performed by heating at 140 ° C. for 30 minutes using a hot air heater, without reducing the viscosity, and phosphoric esterification (anionization) A pure amphoteric starch b was obtained. The analysis was performed in the same manner as in Example 1, and the results are shown in Table 1. (5% B type viscosity is 10
It is 60 mPa · s, which is outside the scope of the present invention. )

(Comparative Example 3) Example in which the viscosity was reduced by post-treatment The amphoteric starch a obtained in Comparative Example 1 was made into a 5% slurry, and ammonium persulfate (oxidizing agent) was added and dissolved at 0.015% to the starch. Slurry 15 using continuous cooking device
Cooking at 0 ° C. for 5 minutes reduced the viscosity by oxidizing ammonium persulfate. The size of the paste solution after cooking is adjusted to pH 6.0 with sodium hydroxide and 5% with warm water.
The post-treatment low-viscosity amphoteric starch c was obtained by re-adjusting the concentration. The B-type viscosity was measured by cooling the paste solution to 50 ° C.

[0028]

[Table 1]

(Test Example) Examples 1 to 4 and Comparative Examples 1 to 3
Using the amphoteric starches A to H and a to c thus obtained, a paper making test of paper was performed as an evaluation test. (1) Preparation of Amphoteric Starch All of the amphoteric starch was made into a slurry with a concentration of 1.0% and heated to 95 ° C
After gelatinizing for 30 minutes, the glue liquid cooled to room temperature was used.

(2) Preparation of Pulp Slurry While stirring 120 g of disaggregated 1.0% waste paper pulp slurry, a sulfuric acid band was used as a solid content and 0.5% of absolute dry pulp.
0.5% and 1.0% of absolute dry pulp as solid content, followed by sizing agent (AKD:
Alkyl ketene dimer) was added as solid content to 0.05% of absolute dry pulp, and then diluted with water to form a 0.3% slurry.

(3) Preparation of test paper The pulp slurry thus prepared was measured with a round sheet machine to have a basis weight of 6
A 0 g / m ² wet sheet was made into paper. Subsequently, it was pressed with a sheet press machine at 5.0 kg / cm ² for 3 minutes, then dried with a rotary dryer at 105 ° C. for 2 minutes, and then 23
C, 50% R.C. H. Humidified overnight.

(4) Evaluation of test paper The prepared test paper was evaluated by the following method. Specific burst strength: Measured according to JIS P 8112. In-layer strength: JAPAN TAPPI test method No. 18
It was measured according to -2. Ash content yield: Measured by ashing the test paper at 575 ° C.

(5) Evaluation of drainage: 300 g of 1.0% disintegrated waste pulp pulp was stirred and sulfuric acid band was added as solid content to 0.5% dry pulp.
0.5% and 1.0% of absolute dry pulp as solid content, followed by sizing agent (AKD:
Alkyl ketene dimer) was added as solid content to the absolute dry pulp in an amount of 0.05%, diluted with water to a 0.3% slurry, immediately poured into a brit jar, and drainage was measured.

(6) Evaluation results The results obtained are shown in Table 2. It was confirmed that the low-viscosity amphoteric starches A to H according to the present invention had a significantly improved strength as compared with the conventional amphoteric starches a and b. It was also reconfirmed that the amphoteric starch c of Comparative Example 3 having a reduced viscosity by post-treatment had no effect. Therefore, as in the present invention, only amphoteric starch, which has been anionized and reduced in viscosity at the same time, does not add starch in the production of paper or paperboard and maintains high drainage and retention while maintaining good drainage and retention. Paper or paperboard can be made.

[0035]

[Table 2]

[0036]

EFFECTS OF THE INVENTION According to the present invention, it is possible to provide an amphoteric starch that exhibits an excellent paper-strengthening effect without addition while maintaining drainage and retention and a method for producing the same. Furthermore, by using the amphoteric starch as an internal additive,
It is possible to make paper or paperboard with high paper strength while maintaining good drainage and retention without adding starch to obtain high paper strength.

   ─────────────────────────────────────────────────── ─── Continued front page    F-term (reference) 4C090 AA02 BA14 BB02 BB12 BB36                       BB62 BB64 BB92 BB96 BD08                       CA29 DA28                 4L055 AC09 AG40 AG48 AH11 AH16                       AH18 EA20 EA25 EA32 FA13

Claims (5)

[Claims] 1. When producing an amphoteric starch for papermaking, a cationic starch having a degree of cation substitution of 0.01 to 0.06 and having a tertiary amine and / or a quaternary ammonium salt introduced thereinto has a slurry pH of 5 after mixing. Urea and inorganic phosphoric acid are added so that the amount becomes 0.0 or less, and then a dry reaction is performed at a roasting reaction at 110 to 180 ° C. to obtain a 5% paste liquid B type viscosity (60 rp).
m, 50 ° C.) is 5 to 500 mPa · s, and an amphoteric starch introduced with a phosphate group having an anion substitution degree of 0.0005 to 0.03 is obtained. 2. The method for producing amphoteric starch according to claim 1, wherein the inorganic phosphoric acid is at least one selected from the group consisting of orthophosphoric acid and alkali metal salts and alkaline earth metal salts of inorganic phosphoric acids. 3. In addition to urea and inorganic phosphoric acid, an inorganic acid and / or
Alternatively, the method for producing amphoteric starch according to claim 2, wherein an organic acid is added. 4. An amphoteric starch obtained by the method according to claim 2 or 3. 5. A method for producing paper or paperboard, which comprises making the pulp slurry containing the amphoteric starch according to claim 4 into paper.