KR100856047B1 - PAPER WHOSE CONTENT OF FLUORESCENT WHITENING AGENTS IS DIMINISHED BY ADDING alpha-AMYLASE AND MANUFACTURING METHOD THEREOF - Google Patents

Abstract

The present invention relates to papermaking and a method for producing the same, wherein the content of the fluorescent brightener is reduced by the addition of α-amylase. In the process of making recycled paper using the paper containing the fluorescent brightener, by adding α-amylase during the dissociation of the raw material pulp, more than about 50% of the fluorescent brightener contained in the waste paper can be removed. .

In addition, since the enzyme is used without using the compound, it is possible to manufacture paper with a reduced content of the optical brightener by an environmentally friendly method.

Fluorescent Whitening Agent, Raw Material Pulp, Dissociation, α-amylase

Description

PAPER WHOSE CONTENT OF FLUORESCENT WHITENING AGENTS IS DIMINISHED BY ADDING α-AMYLASE AND MANUFACTURING METHOD THEREOF}

Figure 1 is a graph showing the relationship between the whiteness and fluorescence index of the sheet according to pH.

2 is a graph showing the relationship between the whiteness of the paper sheet and the fluorescence index according to pH.

3 is a graph obtained by using Equation 3 to determine the concentration of the fluorescent brightener present in the pulp supernatant.

4 is a graph showing the relationship between whiteness and fluorescence index of a sheet of paper according to temperature.

5 is a graph showing the relationship between the whiteness of the paper sheet and the fluorescence index according to the temperature.

6 is a graph obtained by using Equation 3 to determine the concentration of the fluorescent brightener present in the pulp supernatant.

7 is a graph showing the relationship between the whiteness and fluorescence index of herbaceous paper according to the amount of amylase enzyme added.

8 is a graph showing the relationship between the whiteness and the fluorescence index of the grass paper according to the amount of amylase enzyme added.

9 is a graph obtained by using Equation 3 to determine the concentration of the fluorescent brightener present in the pulp supernatant.

FIG. 10 is a graph obtained by calculating the fluorescent brightener content and removal rate of a papermaking paper according to the amount of amylase enzyme added by Equation 2.

The present invention relates to a method for reducing the content of fluorescent substances in sanitary paper, and particularly, among the fluorescent whitening agents (FWA) contained in the raw material and remaining in the waste paper through surface treatment. The present invention relates to a method for separating and removing more than%.

The use of sanitary paper and toilet paper and napkins is continuously increasing to improve the economic and cultural level of Korea. At present, the consumption of toilet paper per capita in Korea has increased rapidly, and this trend is expected to continue in the future.

As raw materials for the production of toilet paper, bleached kraft pulp, which is a natural pulp, and recycled waste papers based on CPO (computer printout) and white ledger are used. Natural pulp is used only for the manufacture of premium premium cosmetic tissues, so most commonly used toilet paper is made from recycled materials. Printing papers such as CPO and white leisure, which are the main raw materials of sanitary paper, require very high whiteness and strength. Therefore, producers of this paper use more and more fluorescent lighteners to meet this characteristic, and the demand for printing paper increases.

Fluorescent whitening agent is one of the most widely used additives for the production of printing paper, which is an important quality standard for whiteness, and is embedded in pulp or chest or escaped to the surface with starch or polyvinyl alcohol in size press.

On the other hand, the optical brightener is based on stilbene (stilbene). Since stilbene is an unsaturated hydrocarbon in which a double bond exists between carbon and carbon, the fluorescent brightener has a compound represented by Formula 1 or an isomer thereof.

At this time, the fluorescent brightener is divided into three types, such as disulpho, tetrasulpho, and hexasulpho, depending on the number of sulfone groups to be introduced.

Fluorescent whitening agent is based on 4,4'-diaminostilbene-2,2'-disulfonic acid (4,4'-diaminostilbene-2,2'-disulfonic acid) and introduces a substituent such as a sulfone group. The number of sulfone groups will be determined.

The type of fluorescent brightener varies depending on the R1 and R2 substituents of Formula 1, and Table 1 shows the types of substituents depending on the type of fluorescent brightener. Regardless of the type of fluorescent brightener, a constant substituent is always attached to the position of R1, but the type of fluorescent brightener is changed as a substituent having a different number of sulfone groups is introduced at the position of R2.

As such, the optical brighteners contained in the inside, the surface, and the coating layer of the paper will inevitably remain in the paper produced again when these papers are recycled. The risk to humans of this residual fluorescent brightener is generally known to have a bad effect. In particular, since hygienic paper is used in contact with the skin, skin side effects and carcinogenic potential are constantly being raised, and the Ministry of Health and Welfare regulates the addition of fluorescent brighteners in the case of food packaging paper. In addition, when recycling the paper to which the fluorescent brightener is added, it is important to remove the fluorescent brightener remaining in the paper.

As a method of removing such a fluorescent brightener, there is a method of adding a liquid containing a triazin UVA compound in the process of treating the fluorescent brightener, as proposed in Japanese Patent Laid-Open No. 2003-502517. .

However, since it contains chemicals such as ammonium group (-NH ₂ ), sulfone group (-SO ₃ ), it is accompanied by toxic and odor, and is not environmentally friendly, there is a problem that handling is difficult in the field.

In addition, methods have been proposed such as decomposition by oxidizing agents, masking with cationic polymers, and addition of raw materials with ultraviolet absorption properties. However, such a method also causes excessive use of chemicals, and there is a problem in that the removal amount of the fluorescent brightener is insufficient.

In order to solve the above problems, the present invention is to propose a method for reducing the amount of fluorescent brightener as much as possible through an environmentally friendly method for producing recycled paper.

In order to achieve the above object, a method of preparing paper in which the amount of fluorescent brightener is reduced by addition of α-amylase according to the characteristics of the present invention is treated with a starch layer containing (a) fluorescent brightener, Dissociating in the pulp and / or the beaker while hydrolyzing the starch layer by adding α-amylase enzyme to the raw pulp treated at a temperature of 65 to 85 ° C., pH 7 to pH 9; (b) passing the dissociated raw pulp through a cleaner and / or screen to remove debris and selecting a stock from the dissociated raw pulp; And (c) a papermaking step of compressing and drying the selected stock and winding the winder.

Paper with reduced content of the fluorescent brightener according to another aspect of the present invention is a paper produced by the above method, the content of the optical brightener in 100 parts by weight of the total paper makes up 0.5 parts by weight or less.

Hereinafter, through the examples and experimental examples of the present invention to verify the optimal pH and temperature conditions for removing the fluorescent brightener, and to determine the appropriate amount of amylase, an environmentally friendly enzyme.

First, before describing the experimental example and the embodiment of the present invention, the papermaking process generally includes a dissociation step, a stock selection step, and a papermaking step.

First, in the beating, the pulp is dissociated in water by using a machine (pulper). At this time, the raw pulp may be subjected to a sizing treatment of mixing the colloidal material having water resistance, or a filler or a dye may be further added.

Next, the papermaking process is completed by passing the beaten raw pulp through a cleaner and / or screen to remove foreign substances, selecting a stock from the beaten raw pulp, compressing and drying the selected stock, and drying the wound. do.

Therefore, in the following experimental example, the experiment was carried out to add the enzyme in the dissociation step, and the stock selection step, the papermaking step, etc. are easily understood by those skilled in the art to which the present invention belongs, so the description thereof will be omitted.

First, in order to prepare a paper for use in the embodiment of the present invention, a white paper sold on the market was used. That is, the white paper was dissociated for 50,000 rev at a concentration of 3.5% using a laboratory dissociator, and then diluted at a concentration of 1.0%.

Using the material produced in such a condition to check the optimal pH and temperature conditions for removing the optical brightener through Example 1 and Example 2.

Example  One

In order to investigate the effect of the pH of the stock on the removal of the fluorescence brightener, the pH of the stock composed of white paper at room temperature was adjusted to 6.5, 7.5, and 8.5, and then stirred at 600 rpm for 1 hour. The pH was adjusted using HCl and NaOH.

After stirring, a paper sheet was produced with a basis weight of 80 g / m 2. In addition, the pulp supernatant was collected by centrifugation for 30 minutes at 500 G and 25 ° C. in order to measure the fluorescent brightener separated from the white paper.

On the other hand, the wet paper prepared to evaluate the removal of fluorescence brightener from woodfree paper under the condition of 23 ℃, 50% RH, and then using a spectrophotometer whiteness, brightness and fluorescence index (fluorescence) index (FI) was measured.

In this case, the fluorescence index is expressed as a difference between whiteness, which is a measured value when the light source includes ultraviolet rays, and whiteness, which is a measured value when UV is removed by a cutoff filter. By using the measured fluorescence index to calculate the content of the fluorescence brightener contained in the white paper and manufactured papermaking paper by using Equation 1, the removal rate was calculated using Equation 2 based on this.

FWA = 1.08 * 0.1 + 6.57 * 0.001 * exp (9.82 * 0.01 * FI)

(FWA: Fluorescent Whitening Agent Content, FI: Fluorescence Index)

% Separation = (A-B) / A * 100

(A: amount of FWA contained in paper before dissociation, B: amount of FWA remaining on paper after physicochemical treatment)

In addition, in order to evaluate the increase and decrease of the fluorescent whitening agent eluted in the pulp supernatant, the fluorescence emission at 438 nm was measured using a fluorescence photometer with a fluorescence excitation wavelength of 337 nm. The fluorescence brightener concentration was determined by substituting the measured fluorescence emission into Equation 3.

FWA = 4.24 * 10 ^-7 * FE + 1.60 * 10 ^-2

(FWA: Fluorescent whitener concentration of pulp supernatant, FI: Fluorescence emission)

Experimental Example  One

Whiteness, whiteness, and respective fluorescence indices of a basin paper having a basis weight of 80 g / m 2 used as a raw material in Example 1 are shown in FIGS. 1 and 2.

That is, Figure 1 is a graph showing the relationship between the whiteness and fluorescence index of the sheet according to pH, Figure 2 is a graph showing the relationship between the whiteness and fluorescence index of the sheet according to pH.

On the other hand, CIE shown in the drawing refers to a standard colorimetric system of the International Standards of the enactment of the International Illumination Commission CIE, ISO means a colorimetric system established by the International Organization for Standardization ISO.

As shown in Figure 1 and 2, it can be seen that the fluorescence index of the paper sheet increases as the pH decreases from 8.5 to 6.5. On the other hand, the whiteness and whiteness of the grasslands increased only while the pH decreased from 8.5 to 7.5 and remained constant at pH below 7.5.

3 is a graph obtained by using Equation 3 to determine the concentration of the optical brightener present in the pulp supernatant. As shown in FIG. 3, the fluorescent index of the sheet and the fluorescent brightener of the supernatant show a proportional relationship. This is because the optical brightener is eluted into the pulp supernatant as it is separated from the regenerated fiber, so that the fluorescence brightener content of the pulp supernatant is increased when the fluorescence index of the paper is high.

In addition, it can be seen that as the pH increases, the amount of the optical brightener present in the supernatant increases. In other words, as the pH decreases, solubility of the fluorescent brightener decreases. This means that as the pH decreases, the affinity for the fiber of the optical brightener increases.

Example  2

In order to investigate the effect of temperature on the removal of the fluorescence brightener, the temperature was adjusted to 25 ° C., 65 ° C. and 80 ° C. under the conditions of pH 8.5, followed by stirring at 600 rpm for 1 hour.

After stirring, a papermaking paper was produced with a basis weight of 80 g / m 2 in the same manner as in Example 1. In addition, the pulp supernatant was collected by centrifugation for 30 minutes at 500 G and 25 ° C. in order to measure the fluorescent brightener separated from the white paper.

Experimental Example  2

The measured values of whiteness, whiteness, and respective fluorescence indices of a basin paper having a basis weight of 80 g / m 2 used in Example 2 are shown in FIGS. 4 and 5.

That is, FIG. 4 is a graph showing the relationship between the whiteness and the fluorescence index of the sheet according to the temperature, and FIG. 5 is a graph showing the relationship between the whiteness and the fluorescence index of the sheet.

As shown in Figures 4 and 5, it can be seen that the fluorescence index of the paper sheet increases as the temperature is increased from 25 ℃ to 80 ℃. The whiteness and whiteness of the sheet also increased as the temperature increased from 25 ° C to 80 ° C. This is because the fluorescent brightener is separated into the pulp supernatant at the same time as the temperature increases.

6 is a graph obtained by using Equation 3 to determine the concentration of the fluorescent brightener present in the pulp supernatant. As shown in Figure 6, the fluorescence index of the paper sheet and the fluorescent brightener of the supernatant shows a proportional relationship. This is because as the temperature increases, the fluorescent brightener is separated from the regenerated fiber and eluted into the pulp supernatant, thereby increasing the content of the fluorescent brightener in the supernatant, thereby increasing the fluorescence index.

Therefore, it can be seen from Experimental Example 1 and Experimental Example 2 that the higher the pH, the higher the temperature, the greater the amount of removal of the fluorescent brightener.

In Example 3 and Experimental Example 3 it is to check the appropriate addition conditions of the enzyme for removing the fluorescent brightener. At this time, the enzyme is applied under the conditions of pH 8.5, 65 ℃ based on the results of Experimental Example 1 and Experimental Example 2.

At this time, the enzyme is applied to the α-amylase enzyme, the α-amylase enzyme is an endo-type that breaks down the β-D- (1-4) glucosidic bond of starch, the activity of the enzyme was 2000WU / ml . Structural formula of the α-amylase enzyme can be easily understood by those of ordinary skill in the art, detailed description thereof will be omitted.

First, in order to prepare a stock for use in Example 3 of the present invention, the stock used in Examples 1 and 2 was produced in the same manner. That is, after dissociating for 50,000 rev at 3.5% concentration using a laboratory dissociator, it was diluted at 1.0% concentration.

Example  3

To investigate the effect of α-amylase enzyme on the removal of fluorescent brightener, α-amylase enzyme was added to the stock diluted to 1.0% at pH 8.5 and 65 ℃, followed by stirring at 600 rpm for 1 hour. 80 g / m 2 of handsheets were produced. And in the same manner as in Example 1 and Example 2 in order to measure the fluorescent brightener separated from the white paper, centrifuged for 30 minutes at 500G, 25 ℃ conditions to collect the pulp supernatant.

Experimental Example  3

The measured values of whiteness, whiteness, and respective fluorescence indices of a basin paper having a basis weight of 80 g / m 2 used as a raw material in Example 3 are shown in FIGS. 7 and 8.

That is, Figure 7 is a graph showing the relationship between the whiteness and fluorescence index of the paper according to the addition amount of α-amylase enzyme, Figure 8 is the relationship between the whiteness and fluorescence index of the paper according to the addition amount of α-amylase enzyme Is a graph.

In FIG. 7 and FIG. 8, the control shows a sheet made of pulp dissociated without adding an enzyme. That is, when only dissociation proceeds as shown in Figure 7, it can be seen that the fluorescent brightener was removed to a significant level. This may be because starch and fluorescence brightener were separated from the white paper by mechanical action during dissociation.

When the temperature of the dissociated stock was not increased while the enzyme was not applied (indicated that 0.0 was added in FIG. 7) at a temperature of 65 ° C., the fluorescent brightener was removed more than the dissociation alone. This result corresponds to the result shown in Example 2.

And, as shown in Figure 7, it can be seen that as the enzyme is added, the separation of the optical brightener further increases. At this time, as the amount of enzyme increased from 4.6 WU to 9.2 WU, the separation of fluorescence brightener was increased, but when it increased to 18.4 WU, there was no significant difference from the removal of 9.2 WU. This is because the input amount of 9.2 WU represents 0.1% of the fiber, so the level of 0.12 WU or more is excessive.

9 is a graph obtained by using Equation 3 to determine the concentration of the fluorescent brightener present in the pulp supernatant. As shown in Figure 9, the fluorescence index of the paper paper and the fluorescent brightener of the supernatant has a proportional relationship, it can be seen that the amount of the fluorescent brightener of the pulp supernatant increases as the amount of the α-amylase enzyme is increased.

FIG. 10 is a graph obtained by calculating the fluorescent whitening agent content and removal rate of a sheet according to the amount of α-amylase enzyme. The removal rate of fluorescent brightener was about 75% at pH 8.5 and 65 ℃. However, when the enzyme of 9.2 WU was added under the same conditions, the removal rate was increased by about 8.5% to 83%. And when the enzyme is added more than 9.2 WU, the removal rate of the optical brightener does not increase any more.

Therefore, according to the embodiments and experimental examples of the present invention, it is possible to increase the amount of fluorescent brightener to be separated by adjusting the pH and temperature of the stock, and further increase the removal of the fluorescent brightener by adding the α-amylase enzyme. .

Although the preferred experimental examples of the present invention have been described in detail above, the scope of the present invention is not limited thereto, and various modifications and improvements of those skilled in the art using the basic concepts of the present invention defined in the following claims are also provided. It belongs to the scope of rights.

The present invention relates to a paper making with reduced amount of fluorescent brightener and a method for producing the same, according to the present invention, it is possible to provide a paper making the removal of at least about 50% of the fluorescent brightener contained in the pulp material in an environmentally friendly manner. Can be.

Claims (10)

(a) Pulper was treated with a starch layer containing a fluorescent brightener and hydrolyzed the starch layer by adding α-amylase enzyme to the raw pulp treated at a temperature of 65 to 85 ° C. and between pH 7 and pH 9. Or dissociating in confession; (b) removing the foreign matter by passing the dissociated raw pulp through a cleaner or screen and selecting a stock from the dissociated raw pulp; And (c) compressing and drying the selected stock and winding the wound around the winder, The α-amylase is an endo-type, the production method of paper making a decrease in the amount of fluorescent brightener. The method of claim 1, The fluorescent brightener is a compound represented by the following formula (2) or a method for producing paper isomers thereof. [Formula 2]

In Chemical Formula 2, R1 is

Is, R2 is

,

or

being. The method of claim 2, The α-amylase is treated with 0.1 parts by weight or less based on 100 parts by weight of the raw material pulp. delete The method of claim 1, The papermaking method of the paper making the content of the optical brightener decreases as the temperature increases. The method of claim 5, The papermaking method of the paper making the content of the optical brightener decreases as the pH of the raw material pulp increases. The method of claim 1, A sizing step of mixing the colloidal material having water resistance to the raw material pulp between steps (a) and (b); And A method of making paper with a reduced content of fluorescent brightener, further comprising the step of adding a filler or dye. The method of claim 1, The raw material pulp is a paper manufacturing method of the surface-sized paper or printing paper. Papermaking prepared according to any one of claims 1 to 3 and 5 to 7. The method of claim 9, Paper making the content of the fluorescent brightener 0.5 parts by weight or less in 100 parts by weight of the total paper.

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