CN105839453B - A kind of papermaking process using calcium silicates and fiber fines compounded mix - Google Patents

Abstract

The invention discloses a papermaking method using calcium silicate and fine fiber composite filler. In the invention, hydrochloric acid is used to compound the calcium silicate filler and fine fiber, and the composite filler is added to the refined plant fiber. Filled paper is obtained after being screened, formed, pressed and dried. The method can significantly improve the strength performance of calcium silicate filled paper, and has significant advantages in the development of high-filled paper.

Description

A papermaking method using calcium silicate and fine fiber composite filler

technical field

The invention belongs to the field of papermaking, and in particular relates to a papermaking method using calcium silicate and fine fiber composite fillers.

Background technique

Adding fillers in the papermaking process can effectively improve the optical properties and printability of paper. On the other hand, since the cost of fillers is lower than that of fibers, the use of fillers is also beneficial to reduce production costs. Therefore, increasing the filler content in paper has become one of the goals pursued by the paper industry. However, adding fillers will reduce the strength properties of paper, which will cause problems such as lint and powder on the paper surface and paper breakage during production. Therefore, the existing literature uses pretreatment of fillers to improve the strength properties of filled paper.

These pretreatment methods include methods such as coating the surface of fillers with hydroxyl-containing polymer materials such as starch and chitosan, or pre-flocculating fillers with polymers, and methods for preparing fine fiber-filler composite fillers. Among them, in the preparation method of the fine fiber-filler composite filler, the method of in-situ synthesis is often adopted, that is, the inorganic filler is synthesized on the fiber or fine fiber to improve the paper-forming performance. However, during the synthesis process, relatively strict technological conditions need to be controlled, such as temperature, pressure, concentration, etc. The formed composite filler is only fine fibers that strengthen the paper, and the filler itself still cannot produce a good combination with the fiber.

Contents of the invention

The purpose of the present invention is to provide a papermaking method using calcium silicate and fine fiber composite filler, to overcome the defects of the above-mentioned prior art, the method of the present invention can be carried out at normal temperature, the control factors are less, and the prepared Composite fillers can significantly improve the strength properties of paper.

To achieve the above object, the present invention adopts the following technical solutions:

A papermaking method using calcium silicate and fine fiber composite filler, comprising the following steps:

Step 1: Mix and refine chemical softwood pulp and chemical hardwood pulp in a ratio of 1:4 to 4:1 to obtain a ground pulp, and then sieve the ground pulp to obtain a fine fiber pulp. After the fiber slurry is concentrated, the fine fiber concentrated slurry is obtained;

Step 2: Prepare the calcium silicate filler as a filler suspension, add fine fiber concentrated slurry to obtain a mixed suspension of fine fiber and calcium silicate, stir the mixed suspension, and gradually add to the filler suspension while stirring A hydrochloric acid solution with a mass concentration of 5% to 30% to make the pH of the mixed suspension = 4 to 6 to obtain a composite of fine fibers and calcium silicate;

Step 3: Separately disintegrate the chemical softwood pulp and chemical hardwood pulp, add water to dilute the chemical softwood pulp and chemical hardwood pulp for refining, and then dilute the refined pulp with water , to obtain diluted slurry;

Step 4: Add fine fiber and calcium silicate compound to the diluted slurry, and mix evenly to form papermaking paper stock; add retention aid to papermaking paper stock, fully mix with papermaking stock, and then form on the Internet, carry out Papermaking.

Further, in step 1, chemical softwood pulp and chemical hardwood pulp are mixed and refined according to a mass ratio of 1:4 to 4:1 to a degree of beating of 50°SR to 90°SR to obtain a milled pulp, and the milled After the slurry passes through a 200-mesh screen, a fine fiber slurry with a size of 2 μm to 76 μm is obtained. After the fine fiber slurry is concentrated, a fine fiber concentrated slurry with a mass concentration of 30% to 70% is obtained.

Further, the calcium silicate filler in step 2 has an average particle size of 10-30 μm, and a whiteness of 85% ISO to 95% ISO.

Further, in the second step, the calcium silicate filler is configured into a filler suspension with a mass fraction of 5-15%.

Further, the absolute dry mass ratio of fine fibers to calcium silicate in the mixed suspension in step 2 is 1:10-10:1.

Further, the stirring speed is 500-800 r/min during the pretreatment of the mixed suspension in step 2.

Further, in step 3, after the chemical softwood pulp and the chemical hardwood pulp are respectively disintegrated, they are diluted with water and the mass concentration of the slurry is 10%, and then the mass ratio of the chemical softwood pulp: chemical hardwood pulp is 1 : 4 carry out refining, after the refining is completed, the pulp after the grinding is diluted with water to a mass concentration of 0.1% to 0.3%, to obtain a diluted slurry with a beating degree of 30 ° SR - 45 ° SR.

Further, the addition amount of the fine fiber and calcium silicate compound in step 4 is 20%-50% of the dry weight in the diluted slurry.

Further, the retention aid in step 4 is cationic polyacrylamide, and its addition amount is 0.3 kg/ton paper to 0.5 kg/ton paper.

Further, in step 4, the retention aid is added to the paper-making paper material, mixed with the paper-making paper material for 20-40 seconds, and then formed on the net for papermaking.

Compared with the prior art, the present invention has the following beneficial technical effects:

In the present invention, after treating calcium silicate with hydrochloric acid, it can stimulate the surface of calcium silicate to generate a large amount of silicon hydroxyl groups, which can form a chemical combination with the hydroxyl groups on the surface of fine fibers, thereby forming a composite filler of calcium silicate and fine fibers. , because the surface activity of the filler is improved after being treated with hydrochloric acid, during the paper forming process, on the one hand, the filler itself can form a chemical bond with the hydroxyl groups on the surface of the fibers used in papermaking; The fibers used form hydrogen bonds, and under the action of the two, they jointly promote the improvement of the strength performance of the filled paper. The experimental results show that under the same paper weight, papermaking process and filler content, the tensile strength and tear strength of the paper filled with composite fillers are better than those of the filled paper without compound treatment. The improvement of α indicates that the binding force between the filler and the fiber is improved after the pretreatment of the filler, which means that there is room for further increase of the filler content, which meets the requirements of high-filler papermaking.

Detailed ways

Below in conjunction with embodiment the present invention is described in further detail:

Example 1

Step 1: The chemical softwood pulp and the chemical hardwood pulp are mixed and refined according to the ratio of 1:4 to a beating degree of 50°SR to obtain a ground pulp, and then the ground pulp is passed through a 200-mesh sieve to obtain a size of 2 μm fine fiber slurry, after concentrating the fine fiber slurry, a fine fiber concentrated slurry with a mass concentration of 30% is obtained;

Step 2: configure the calcium silicate filler into a filler suspension with a mass fraction of 5%, add fine fiber concentrated slurry to obtain a mixed suspension of fine fiber and calcium silicate, and mix the fine fiber and calcium silicate in the suspension The absolute-dry mass ratio of the mixture is 1:10, and the mixed suspension is stirred at a speed of 500r/min. While stirring, a hydrochloric acid solution with a mass concentration of 5% is gradually added to the filler suspension to make the mixed suspension pH=4 , get fine fiber and calcium silicate composite;

Step 3: After disintegrating the chemical softwood pulp and chemical hardwood pulp respectively, add water to dilute the pulp so that the mass concentration of the pulp is 10%, and then carry out according to the mass ratio of chemical softwood pulp: chemical hardwood pulp is 1:4 Refining, after the refining is completed, dilute the ground pulp with water to a mass concentration of 0.1%, to obtain a diluted pulp with a beating degree of 30°SR;

Step 4: Add fine fiber and calcium silicate compound to the diluted slurry, wherein the added amount of the fine fiber and calcium silicate compound is 20% of the absolute dry weight in the diluted slurry, and mix evenly to form papermaking paper stock Add cationic polyacrylamide to the papermaking paper stock at an amount of 0.3 kg/ton of paper, fully mix it with the papermaking paper stock for 20 seconds, and then form it on the Internet for papermaking. The physical properties of the obtained paper are shown in Table 1.

Table 1 embodiment 1 paper physical performance testing result

Example 2

Step 1: The chemical softwood pulp and the chemical hardwood pulp are mixed and refined according to the ratio of 4:1 to a beating degree of 90°SR to obtain a ground pulp, and then the ground pulp is passed through a 200-mesh sieve to obtain a size of 76 μm fine fiber slurry, after the fine fiber slurry is concentrated, the fine fiber concentrated slurry with a mass concentration of 70% is obtained;

Step 2: configure the calcium silicate filler into a filler suspension with a mass fraction of 15%, add fine fiber concentrated slurry to obtain a mixed suspension of fine fiber and calcium silicate, and mix the fine fiber and calcium silicate in the suspension The absolute-dry mass ratio of the mixture is 10:1, and the mixed suspension is stirred at a speed of 800r/min. While stirring, a hydrochloric acid solution with a mass concentration of 30% is gradually added to the filler suspension to make the pH of the mixed suspension=6 , get fine fiber and calcium silicate composite;

Step 3: After disintegrating the chemical softwood pulp and chemical hardwood pulp respectively, add water to dilute the pulp so that the mass concentration of the pulp is 10%, and then carry out according to the mass ratio of chemical softwood pulp: chemical hardwood pulp is 1:4 Refining, after the refining is completed, dilute the ground pulp with water to a mass concentration of 0.3%, to obtain a diluted pulp with a beating degree of 45°SR;

Step 4: Add fine fiber and calcium silicate compound to the diluted slurry, wherein the addition amount of the fine fiber and calcium silicate compound is 50% of the absolute dry weight in the diluted slurry, and mix evenly to form papermaking paper stock Add cationic polyacrylamide into the papermaking paper stock at an amount of 0.5 kg/ton of paper, mix it fully with the papermaking paper stock for 40 seconds, and then form it on the Internet for papermaking. The physical properties of the obtained paper are shown in Table 2.

Table 2 embodiment 2 paper physical performance testing result

Example 3

Step 1: Mix and refine the chemical softwood pulp and the chemical hardwood pulp in a ratio of 1:1 until the degree of beating is 70°SR to obtain a ground pulp, and then pass the ground pulp through a 200-mesh sieve to obtain a size of 50 μm fine fiber slurry, after concentrating the fine fiber slurry, obtain a fine fiber concentrated slurry with a mass concentration of 50%;

Step 2: configure the calcium silicate filler into a filler suspension with a mass fraction of 10%, add fine fiber concentrated slurry to obtain a mixed suspension of fine fiber and calcium silicate, and mix the fine fiber and calcium silicate in the suspension The absolute-dry mass ratio of the mixture is 1:1, and the mixed suspension is stirred at a speed of 600r/min. While stirring, a hydrochloric acid solution with a mass concentration of 20% is gradually added to the filler suspension to make the pH of the mixed suspension = 5 , get fine fiber and calcium silicate composite;

Step 3: After disintegrating the chemical softwood pulp and chemical hardwood pulp respectively, add water to dilute the pulp so that the mass concentration of the pulp is 10%, and then carry out according to the mass ratio of chemical softwood pulp: chemical hardwood pulp is 1:4 Refining, after the refining is completed, dilute the ground pulp with water to a mass concentration of 0.2%, to obtain a diluted slurry with a beating degree of 40°SR;

Step 4: Add fine fiber and calcium silicate compound to the diluted slurry, wherein the added amount of the fine fiber and calcium silicate compound is 30% of the absolute dry weight in the diluted slurry, and mix evenly to form papermaking paper stock Add cationic polyacrylamide to the papermaking paper stock at an amount of 0.4 kg/ton of paper, fully mix it with the papermaking paper stock for 30 seconds, and then form it on the Internet for papermaking. The physical properties of the obtained paper are shown in Table 3.

Table 3 embodiment 3 paper physical property testing result

The above results show that under the same paper weight, papermaking process and filler content, the tensile strength and tear strength of the paper filled with composite fillers are better than those of paper filled with calcium silicate fillers. The improvement of strength properties indicates that the composite filler improves the binding force between filler and fiber, which means that there is room for further increase of filler content, which is beneficial to the development of high-filler paper.

Claims (7)

1. A papermaking method that adopts calcium silicate and fine fiber composite filler, is characterized in that, comprises the following steps: Step 1: Mix and refine the chemical softwood pulp and chemical hardwood pulp according to the mass ratio of 1:4 to 4:1 to a beating degree of 50°SR to 90°SR to obtain a ground pulp, and grind the pulp Passing through a 200-mesh sieve to obtain a fine fiber slurry with a size of 2 μm to 76 μm, and after concentrating the fine fiber slurry, obtain a fine fiber concentrated slurry with a mass concentration of 30% to 70%; Step 2: Prepare the calcium silicate filler into a filler suspension with a mass fraction of 5-15%, add fine fiber concentrated slurry to obtain a mixed suspension of fine fiber and calcium silicate, and mix the fine fiber and silicic acid in the suspension The absolute-dry mass ratio of calcium is 1:10-10:1. Stir the mixed suspension. While stirring, gradually add hydrochloric acid solution with a mass concentration of 5%-30% to the filler suspension to make the pH of the mixed suspension =4～6, obtain fine fiber and calcium silicate compound; Step 3: Separately disintegrate the chemical softwood pulp and chemical hardwood pulp, add water to dilute the chemical softwood pulp and chemical hardwood pulp for refining, and then dilute the refined pulp with water , to obtain diluted slurry; Step 4: Add fine fiber and calcium silicate compound to the diluted slurry, and mix evenly to form papermaking paper stock; add retention aid to papermaking paper stock, fully mix with papermaking stock, and then form on the Internet, carry out Papermaking. 2. A papermaking method using calcium silicate and fine fiber composite filler according to claim 1, characterized in that the calcium silicate filler in step 2 has an average particle diameter of 10-30 μm and a whiteness of 85%ISO ~95% ISO. 3. A papermaking method using calcium silicate and fine fiber composite filler according to claim 1, characterized in that, in step 2, the stirring speed is 500-800 r/min when the mixed suspension is pretreated. 4. a kind of papermaking method that adopts calcium silicate and fine fiber composite filler according to claim 1, it is characterized in that, after chemical coniferous wood pulp and chemical broad-leaved wood pulp are respectively disintegrated in step 3, add water to dilute and The mass concentration of the pulp is 10%, and then the mass ratio of chemical softwood pulp: chemical hardwood pulp is 1:4 for refining. After the refining is completed, the refined pulp is diluted with water to a mass concentration of 0.1%~ 0.3% to obtain a diluted slurry with a beating degree of 30°SR to 45°SR. 5. A kind of papermaking method that adopts calcium silicate and fine fiber composite filler according to claim 1, it is characterized in that, the add-on of fine fiber and calcium silicate compound in the step 4 is the absolute dry weight in the diluted slurry 20% to 50% of that. 6. A kind of papermaking method that adopts calcium silicate and fine fiber composite filler according to claim 1, is characterized in that, the retention aid in step 4 is cationic polyacrylamide, and its addition is 0.3 kilogram/ton paper ~0.5 kg/ton of paper. 7. A kind of papermaking method that adopts calcium silicate and fine fiber composite filler according to claim 1, it is characterized in that, in step 4, retention aid is added in the papermaking paper stock, mixes with papermaking paper stock for 20～ After 40s, it is formed on the Internet and papermaking is carried out.