JP4339242B2 - Bleach activator for pulp - Google Patents

Description

  The present invention relates to a bleach activator for pulp when producing paper.

  Since the cellulose pulp obtained by mechanical or chemical treatment is somewhat colored, it is bleached to increase the whiteness. As bleaching agents used for pulp bleaching, oxygen bleaching agents such as oxygen and hydrogen peroxide are known. The whiteness of the bleached pulp is important because it greatly affects the whiteness of the pulp sheet and paper.

A technique for activating an oxygen bleach by using a bleach activator in combination with an oxygen bleach has been proposed. For example, Patent Documents 1 and 2 disclose sugars and sugar acylated products, and Patent Document 3 discloses a carbonyl compound having an aromatic ring.
JP-A-4-309599 Japanese Patent Laid-Open No. 5-186888 JP-A-1-104893

  However, in recent years, demands for improving the whiteness of pulp sheets and paper are further increasing, and in particular, there is a demand for a technology that can further increase the whiteness by increasing the amount of used paper pulp accompanying the promotion of reuse of used paper. From this point of view, it is difficult to say that the technique of the patent document presented above still provides a bleached pulp from which a pulp sheet that can sufficiently satisfy all of whiteness and strength can be obtained. There is also a demand for liquid chemicals in terms of workability in the bleaching process.

  The subject of this invention is providing the bleaching activator for pulp from which a pulp sheet with high whiteness is obtained. Moreover, it is providing the method which can manufacture the bleached pulp from which a pulp sheet with high whiteness is obtained.

  The present invention relates to a bleaching activator for pulp, which is an ester of a polyhydric alcohol and an organic acid having a hydrocarbon group which may have a hydroxyl group, and is made of a compound that is liquid at 25 ° C.

  Moreover, this invention relates to the manufacturing method of the bleached pulp which manufactures bleached pulp from raw material pulp using the bleaching activator for pulps of the said this invention, and an oxidizing agent.

  By using the bleaching activator for pulp of the present invention, bleached pulp having high whiteness can be produced. Moreover, since the bleaching activator for pulp of the present invention is liquid at 25 ° C., it is excellent in terms of workability in the bleaching process.

<Bleaching activator for pulp>
The bleaching activator for pulp of the present invention, which is an ester of a polyhydric alcohol and an organic acid having a hydrocarbon group which may have a hydroxyl group, is liquid at 25 ° C. and reacts with an oxidizing agent such as hydrogen peroxide. Thus, an organic peracid is generated (hereinafter, such ester compound is also referred to as component (A)). Since the component (A) is in a liquid state at 25 ° C., it is excellent in workability in the pulp bleaching process, such that pre-dissolution at the time of addition is unnecessary and that it can be weighed with a flow meter.

  Here, the liquid state means that it is 10,000 mPa · s or less (B type viscometer, No. 3 rotor, 12 rpm, 1 minute) at 25 ° C.

  (A) As a polyhydric alcohol for comprising a component, what has 2-20 hydroxyl groups is preferable, and what has 2-6 especially is preferable.

  Moreover, as a polyhydric alcohol for comprising (A) component, a C2-C12 thing is preferable and glycerol, such as glycerol, diglycerol, and triglycerol, is mentioned. Of these, glycerin is preferable.

  The organic acid for constituting the component (A) includes aliphatic monocarboxylic acids such as acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, octanoic acid, oxalic acid, malonic acid, succinic acid, maleic acid. , Aliphatic dicarboxylic acids such as fumaric acid, hydroxycarboxylic acids having a hydroxyl group such as citric acid, tartaric acid, malic acid, etc., preferably saturated or unsaturated aliphatic mono- or dicarboxylic acids having 2 to 8 carbon atoms More preferably, a C2-C8 saturated or unsaturated aliphatic monocarboxylic acid is mentioned, More preferably, a C2-C8 fatty acid is mentioned. Although the degree of esterification of (A) component is not limited, 0.5-1 are preferable.

  Specific examples of the component (A) include esters of glycerin and aliphatic monocarboxylic acids having 2 to 8 carbon atoms, and triacetin and diacetin are particularly preferable.

<Method for producing bleached pulp>
The method for producing bleached pulp according to the present invention produces bleached pulp from raw pulp using the bleaching activator for pulp according to the present invention [component (A)] and an oxidizing agent (hereinafter also referred to as component (B)). To do.

  Examples of the component (B) include those other than those generated from the component (A) and acting as an oxidizing agent, such as ozone, oxygen, percarbonate, hydrogen peroxide, perborate, and superphosphate. And metal peroxides. Of these, hydrogen peroxide is preferable.

  The raw material pulp that can be used in the production method of the present invention is a cellulose-containing material. For example, GP (ground wood pulp), RMP (refiner mechanical pulp), TMP (thermomechanical pulp), CGP (chemiground pulp), SCP (semi Chemical pulp), SP (sulfite pulp), KP (craft pulp), AP (alkaline pulp), waste paper pulp, etc. can be mentioned, and can be applied to any wood (conifer, broadleaf), non-wood (herbaceous) pulp is there. Moreover, the slurry concentration of the cellulose-containing material in the bleaching step can be applied to any of a low concentration (less than 10% by weight), a medium concentration (10 to 20% by weight), and a high concentration (20% by weight or more). Waste paper pulp includes deinked pulp obtained by deinking waste paper pulp.

  The amount of component (A) used may be adjusted according to the target whiteness and the type of raw pulp, but is preferably 0.01 to 10 parts by weight with respect to 100 parts by weight of raw pulp (absolutely dry). -5 parts by weight is particularly preferred.

  (B) Although the usage-amount of a component should just adjust with the target whiteness, the kind of raw material pulp, etc., 0.01-10 weight part is one standard with respect to 100 weight part of raw material pulp (absolute dryness). .

  The weight ratio of the component (A) to the component (B) is preferably (A) / (B) = 1/99 to 99/1, particularly preferably 10/90 to 85/15.

  The method for producing bleached pulp of the present invention includes, for example, preparing a water-pulp slurry containing raw pulp and water, and bleaching the raw pulp in the presence of the components (A) and (B). In the present invention, the order of adding the component (A) and the component (B) is not limited, but the component (A) is preferably added first. It is presumed that the effect on the raw material pulp is enhanced by the fact that the (A) component can be uniformly dispersed in the raw material pulp before the (B) component and the (A) component react.

  These additions are preferably carried out at room temperature (25 ° C.) or less where the bleaching reaction hardly occurs. When hydrogen peroxide is used as the component (B), it is preferable to bleach the raw pulp under an alkaline region using an alkali agent such as sodium hydroxide or sodium silicate. The pulp slurry temperature during bleaching is preferably 40 to 100 ° C. Generally, there is a contradictory relationship between the bulk (tightness) and strength of paper, and when hydrogen peroxide is used as the component (B), from the viewpoint of maintaining the bulk (tightness) and strength of paper before bleaching. The pulp slurry temperature during bleaching is preferably 50 ° C. or less. Compared with the same bulk paper, the strength is excellent, and compared with the same strength paper, the bulk becomes high. The pulp that has been bleached is appropriately cooled and diluted, and then subjected to a papermaking process to produce a pulp sheet.

  Using the components (A) and (B) shown in Table 1, the raw material pulp was bleached as follows, and the performance of the pulp sheet produced from the obtained bleached pulp was evaluated. The results are shown in Table 1.

(1) Preparation of pulp before bleaching Unprinted newspaper used was used as a pulp raw material so that the whiteness could be easily compared. 120 g of unprinted newspaper waste paper was weighed by dry pulp weight to prepare a raw material for pulp slurry having a pulp concentration of 15% by weight. To this, a chemical usually used in the deinking process was added. That is, sodium hydroxide 1.2% by weight (vs. pulp dry weight), sodium silicate 1.2% by weight (vs. pulp dry weight), DI-767 (manufactured by Kao Corporation, polyoxyalkylene alkyl ether type nonionic interface) The activator was added in an amount of 0.2% by weight (vs. pulp dry weight) and disaggregated at 40 ° C. for 7 minutes under stirring at 450 rpm. Next, it was dehydrated to a pulp concentration of 26% by weight with an 80 mesh wire to prepare a pulp slurry before bleaching.

(2) Bleaching The pre-bleached pulp slurry is collected so that the dry weight is 40 g. Separately, an alkaline aqueous solution of 1.2 wt% sodium hydroxide (vs. pulp dry weight) and 1.2 wt% No. 3 sodium silicate (vs. pulp dry weight) was prepared. After adding and homogenizing, it was added to the pulp slurry. Next, the component (B) in Table 1 was added to the pulp slurry to adjust the pulp slurry to a pulp concentration of 25% by weight. Next, the mixture was mixed at room temperature (25 ° C.) using a PFI mill (clearance 0.6 mm / 300 rpm) and bleached at 45 ° C. or 60 ° C. for 2 hours. Thereafter, it was immersed in ice water and the pulp was cooled to finish bleaching.

(3) Papermaking The pulp concentration in the pulp slurry after bleaching is diluted with water so as to be 2% by weight, and then re-dissociated with a standard dissociator (3000 rpm, 30 seconds, room temperature (25 ° C.)), and the pulp concentration Was diluted with water to 1% by weight, and a paper to which 10% by weight of aluminum sulfate (sulfuric acid band) was added (vs. dry weight of pulp) was used to make paper with a tappi paper machine, and then 105 ° C with a drum dryer. And dried for 2 minutes to prepare a pulp sheet having a basis weight of 150 g / m ² .

(4) Evaluation The whiteness, tightness, and burst strength of the pulp sheet were measured by the following methods.

(4-1) Whiteness
According to JIS P 8123 Hunter Whiteness. A difference of 0.5 points in whiteness is fully recognized as a significant difference.

(4-2) Tension The basis weight (g / m ² ) and thickness (mm) of the conditioned sheet were measured, and the tension (g / cm ³ ) was determined by the following formula.
Tension = (basis weight) / (thickness) × 0.001
The smaller the tension is, the higher the bulk is, and a difference of 0.005 in the tension is well recognized as a significant difference.

(4-3) Burst strength Burst strength was measured by JIS P8112 method as a paper strength measurement item. The 0.05 point difference in burst strength is well recognized as a significant difference.

* In the table, unbleached is the result of the pulp sheet produced from the pulp slurry before bleaching by the paper making method of (3) above, and PFI treatment is mixed with PFI mill without adding chemicals to the pulp slurry before bleaching (clearance 0) 6 mm, 300 revolutions).

Claims (7)

Water-pulp slurry containing pulp and water in the presence of a bleaching activator for pulp selected from triacetin and diacetin (hereinafter referred to as component (A)) and hydrogen peroxide (hereinafter referred to as component (B)) A method for producing bleached pulp in which bleached pulp is produced from [hereinafter referred to as pulp slurry], wherein the raw material pulp is bleached at a pulp slurry temperature of 50 ° C. or lower . The manufacturing method of the bleached pulp of Claim 1 which adds (B) component after adding (A) component to a pulp slurry. The manufacturing method of the bleached pulp of Claim 1 or 2 whose temperature of a pulp slurry when adding (A) component and (B) component is 25 degrees C or less. The method for producing bleached pulp according to any one of claims 1 to 3, wherein the amount of component (A) used is 0.01 to 10 parts by weight with respect to 100 parts by weight of raw pulp (absolutely dry). (B) The manufacturing method of the bleached pulp of any one of Claims 1-4 whose usage-amount of a component is 0.01-10 weight part with respect to 100 weight part of raw material pulp (absolute dryness). The method for producing bleached pulp according to any one of claims 1 to 5, wherein the component (A) and the component (B) are used in a weight ratio of (A) / (B) = 1/99 to 99/1. The method for producing bleached pulp according to any one of claims 1 to 6, wherein the pulp slurry contains an alkali agent and bleaches the raw material pulp in an alkaline region.