A method for manufacturing high basis weight matte coated paper on a single-layer twin-wire paper machine

Abstract

The present invention provides a method for manufacturing high-basis-weight matte coated paper on a single-layer twin-wire paper machine. The high-basis-weight matte coated paper of the present invention is based on the single-layer twin-wire base paper and is manufactured on a high-speed paper machine with a speed of up to 1000 m / min. The industry-unique three-pass MSP (double-sided top coating) + four-pass blade multi-layer coating process is adopted, and the bulk of the formed paper is greater than 0.95 cm 3 / g, the roughness is ≤ 1.6 μm, and the ISO brightness is ≥ 88%, which can meet the requirements of high-grade printing and packaging

Description

Technical Field

[0001] The present invention relates to the technical field of papermaking, and particularly relates to a method for manufacturing high-basis-weight matte coated paper on a single-layer twin-wire paper machine. Background Art

[0002] High-basis-weight paper refers to paper with a basis weight of at least 300 g / m 2 , and currently, high-basis-weight paper generally uses multi-layer wire paper machines to manufacture cardboard or paperboard. The basis weight of paper produced by a single-layer wire paper machine is generally within 300 gsm. Due to the low basis weight, it cannot meet the requirements of high-grade packaging. Since the basis weight of the finished paper is too high, the basis weight of the base paper will also increase accordingly. Therefore, it is difficult to fully dehydrate and dry the high basis weight of the base paper at high speeds. When high-basis-weight matte coated paper is used for packaging, it is prone to bursting at the folding position, affecting the appearance and use. In the prior art, CN102758383B, a method for producing high-bulk packaging paperboard, prepares a surface layer, a liner layer, a core layer, and a bottom layer respectively, and then uses an adhesive to bond and prepare a high-bulk packaging paperboard. The present invention proposes a method for using a high-speed single-layer twin-wire to manufacture high-basis-weight matte coated paper. Summary of the Invention

[0003] In view of this, the present invention is proposed to solve the above problems.

[0004] The technical solution of the present invention is realized as follows:

[0005] A method for manufacturing high-basis-weight matte coated paper on a single-layer twin-wire paper machine, comprising the following steps:

[0006] S1. Mix and beat sulfate softwood pulp, bleached sulfate hardwood pulp, and alkaline hydrogen peroxide mechanical pulp to obtain a pulp;

[0007] S2. Add ground calcium carbonate and cationic starch to the pulp, and make a web on the paper machine to obtain a base paper;

[0008] S3. Use starch sizing solution to size the base paper by film transfer double-sided sizing method to obtain a sized base paper;

[0009] S4. Apply a bottom coat to the sized base paper. The bottom coat coating, by weight, includes 42-88 parts of ground calcium carbonate C55 grade, 0-44 parts of ground calcium carbonate C65 grade, 12-15 parts of an adhesive, 0.05-0.20 parts of a dispersant, 0.02-0.08 parts of an antifoaming agent, and 0.3-0.8 parts of a thickener to obtain a bottom-coated paper;

[0010] S5. Apply the intermediate coating to the primed base paper. The intermediate coating composition, by weight, comprises 88 - 90 parts of ground calcium carbonate C55 grade, 9 - 13 parts of adhesive, 0.05 - 0.2 parts of dispersant, 0.02 - 0.08 parts of defoamer, and 0.4 - 0.8 parts of thickener, to obtain the paper after intermediate coating.

[0011] S6. Apply the top coating to the paper after intermediate coating. The top coating composition, by weight, comprises 28 - 38 parts of ground calcium carbonate C65 grade, 53 - 63 parts of ground calcium carbonate C98 grade, 8 - 12 parts of adhesive, 0.05 - 0.20 parts of dispersant, 0.02 - 0.08 parts of defoamer, 0.1 - 0.3 parts of lubricant, and 0.3 - 0.8 parts of thickener, to obtain the paper after top coating.

[0012] S7. Calender the paper after top coating to obtain the finished product.

[0013] Further, in step S1, the mass ratio of the sulfate softwood pulp, bleached sulfate hardwood pulp, and alkaline peroxide mechanical pulp is 20 - 25:50 - 60:20 - 30.

[0014] Further, in step S1, the freeness of the sulfate softwood pulp after beating is 380 - 420 ml, and the bulk is 1.2 - 1.4 cm 3 / g; the freeness of the bleached sulfate hardwood pulp after beating is 360 - 420 ml, and the bulk is 1.2 - 1.4 cm 3 / g; the freeness of the alkaline peroxide mechanical pulp after beating is 360 - 400 ml, and the bulk is above 2.7 cm 3 / g.

[0015] Further, in step S2, the mass ratio of the pulp, ground calcium carbonate, and cationic starch is 65 - 70:30 - 35:0.8 - 1.2. The ground calcium carbonate is the particles with a particle size less than 2 μm after being treated with polymer, and the content of such particles is 20 - 40%. The content of particles with a particle size less than 2 μm in the ground calcium carbonate C60 is 58 - 62%. The wire section speed during the on - wire papermaking is 950 - 1050 m / min, the pulp - to - wire speed ratio is 1.04 - 1.05, the first press nip pressure is 1000 - 1200 kN / m, the second press nip pressure is 1000 - 1100 kN / m, the hard calendering pressure is 30 - 40 kN / m. The moisture content of the base paper is 8 - 16%, the basis weight is 230 - 270 g / m 2 , and the whiteness is above 68%.

[0016] Further, in step S3, the mass concentration of the starch sizing solution is 12 - 14%, the low - shear viscosity is 12 - 14 cps, and the total sizing application amount by film transfer is 1.5 - 4 g / ㎡.

[0017] Further, in step S4, the solid content of the primer coating is 60 - 67%, the low-shear viscosity is 400 - 600 cps, the film transfer coating amount is 30 - 50 g / ㎡, the primer metering bar pressure is upper roll / lower roll: 1.4 - 1.8 / 1.4 - 1.8 bar, the content of particles with a particle size less than 2 um in the ground calcium carbonate C55 is 52 - 57%, and the content of particles with a particle size less than 2 um in the ground calcium carbonate C65 is 62 - 67%.

[0018] Further, in step S5, the solid content of the intermediate coating is 68 - 72%, the low-shear viscosity is 800 - 1000 cps, the total doctor blade coating amount is 20 - 30 g / ㎡, the intermediate coating doctor blade pressure is 30 - 50%, and the content of particles with a particle size less than 2 um in the ground calcium carbonate C55 is 52 - 57%.

[0019] Further, in step S6, the solid content of the top coating is 65 - 68%, the low-shear viscosity is 1000 - 1300 cps, the total top coating amount is 18 - 30 g / ㎡, the top coating doctor blade pressure is 30 - 50%, the content of particles with a particle size less than 2 um in the ground calcium carbonate C65 is greater than 63%, and the content of particles with a particle size less than 2 um in the ground calcium carbonate C98 is greater than 98%.

[0020] Further, in step S7, the calendering is to use a super calender to calender and modify the paper surface. The calender uses a single nip 9-zone configuration, the calendering temperature is 60 °C, the line pressure is 90 kN / m, and the lower wire side is calendered once.

[0021] Further, the adhesive is at least one of styrene-butadiene latex and bio-latex, the dispersant is sodium polyacrylate, the defoamer is a higher fatty alcohol, and the thickener is at least one of carboxymethyl cellulose and sodium carboxymethyl cellulose.

[0022] Compared with the prior art, the beneficial effects of the present invention are:

[0023] The high-basis-weight matte coated paper of the present invention is manufactured based on a single-layer twin-wire base paper. On a high-speed paper machine with a speed of up to 1000 m / min, it adopts the industry-unique three-pass MSP (double-sided top coating) + four-pass doctor blade multi-layer coating process.

[0024] The base paper of the present invention is manufactured based on a single-layer twin-wire base paper, using sulfate softwood pulp, bleached sulfate hardwood pulp, and alkaline hydrogen peroxide mechanical pulp (the bulk is above 2.7 cm 3 / g and the whiteness is above 68%), ground calcium carbonate, and cationic starch, and strictly controlling reasonable ratios, the ash content of the base paper, and the forming and surface structure and other properties of the base paper to ensure that the high-basis-weight base paper can be fully dehydrated and dried at high speeds, laying a foundation for the production of high-basis-weight coated paper.

[0025] The present invention uses a coating formulation exclusive to high basis weight matte coated paper, and different raw material ratios are used for the base coat, middle coat, and top coat. Three passes of MSP (double-sided top coating) + four passes of blade coating are carried out to maintain a reasonable micro-roughness on the paper surface through technical means. Through multi-layer coating, the basis weight of the formed paper meets the requirements of high-grade printing and packaging.

[0026] The present invention strictly controls the production process. According to the solution of the present invention, the basis weight of the formed paper is 330 - 350 gsm, the bulk of the formed paper is ≥ 0.95 cm 3 / g, the roughness is ≤ 1.6 um, the ISO brightness is ≥ 88%, and the folding endurance is ≥ 3 times. Detailed implementation manners

[0027] To better understand the technical content of the present invention, specific embodiments are provided below to further illustrate the present invention.

[0028] Unless otherwise specified, the experimental methods used in the embodiments of the present invention are all conventional methods.

[0029] Unless otherwise specified, the materials, reagents, etc. used in the embodiments of the present invention can all be obtained from commercial channels.

[0030] Embodiment - A method for making high basis weight matte coated paper on a single-layer twin-wire paper machine, comprising the following steps:

[0031] S1: Take softwood kraft pulp, bleached hardwood kraft pulp, and alkaline hydrogen peroxide mechanical pulp, and mix them in a weight ratio of 23:53:24 to form a pulp mixture; after beating, the freeness of the softwood kraft pulp is 410 ml, and the bulk is 1.3 cm 3 / g; after beating, the freeness of the bleached hardwood kraft pulp is 390 ml, and the bulk is 1.3 cm 3 / g; after beating, the freeness of the alkaline hydrogen peroxide mechanical pulp is 380 ml, and the bulk is 2.9 cm 3 / g, and the brightness is 71%.

[0032] S2: Add ground calcium carbonate and cationic starch to the pulp mixture in step S1 and mix well to obtain the base paper pulp; by weight, the base paper pulp includes 66% of the pulp mixture, 33% of ground calcium carbonate of grade C60, and 0.95% of cationic starch. The ground calcium carbonate is particles with a particle size less than 2 um after treating ground calcium carbonate C60 with a polymer (polyacrylic acid), and the content of such particles is 29%. The ground calcium carbonate C60 has a particle content of less than 2 um of 60%. The wire section speed is 1000 m / min, the pulp-to-wire speed ratio is 1.045, the first press nip pressure is 1100 kN / m, the second press nip pressure is 1050 kN / m, and the hard calendering pressure is 35 kN / m.

[0033] S3: Use the pulp of the base paper obtained in step S2 to produce the base paper. The basis weight of the produced base paper is 260 g / m 2 , with a moisture content of 11.5%;

[0034] S4: On the basis of step S3, perform film transfer double-sided sizing using a starch sizing solution with a mass concentration of 13%, a low shear viscosity of 13 cps, and a total film transfer sizing amount of 2 g per square meter of coated paper to size the surface of the obtained base paper;

[0035] S5: On the basis of step S4, perform two-time film transfer double-sided coating for the bottom coating. The solid content of the first bottom coating paint is 62%, the low shear viscosity is 460 cps, and the total film transfer coating amount per square meter of coated paper is 23 g; the solid content of the second bottom coating paint is 64.5%, the low shear viscosity is 500 cps, and the total film transfer coating amount per square meter of coated paper is 24 g. The pressure of the bottom coating metering rod: upper roller / lower roller: 1.4 - 1.8 / 1.4 - 1.8 bar; by weight, the bottom coating paint for film transfer coating includes 43 parts of ground calcium carbonate C55 grade, 43 parts of ground calcium carbonate C65 grade, 13 parts of adhesive, 0.05 parts of dispersant, 0.05 parts of defoamer, and 0.54 parts of thickener. The ground calcium carbonate C55 has a particle size less than 2 um with a content within 52 - 56%, the ground calcium carbonate C65 has a particle size less than 2 um with a content within 62 - 66%, the adhesive is styrene-butadiene latex, the dispersant is sodium polyacrylate, the defoamer is higher fatty alcohol, and the thickener is carboxymethyl cellulose.

[0036] S6: On the basis of step S5, perform two-time knife coating, coating one side each time, for the middle coating. The solid content of the paint is 71%, the low shear viscosity is 980 cps, and after completion, each square meter of paper contains a total knife coating amount of 26 g. The knife pressure for the middle coating is 35 - 60%; by weight, the paint for the middle coating by knife coating includes 89 parts of ground calcium carbonate C65 grade, 10.7 parts of adhesive, 0.1 parts of dispersant, 0.03 parts of defoamer, and 0.57 parts of thickener. The ground calcium carbonate C65 has a particle size less than 2 um with a content within 62 - 66%, the adhesive is styrene-butadiene latex, the dispersant is sodium polyacrylate, the defoamer is higher fatty alcohol, and the thickener is carboxymethyl cellulose.

[0037] S7: Based on step S6, two passes of blade coating are carried out, with each side coated once for surface coating. The solid content of the coating is 68%, the low-shear viscosity is 1200 cps. After completion, the total surface coating amount per square meter of paper is 21 g, and the blade pressure for surface coating is 30 - 55%. By weight, the coating for blade coating in surface coating includes 31.5 parts of ground calcium carbonate C65 grade, 58.5 parts of ground calcium carbonate C98 grade, 10 parts of adhesive, 0.15 parts of dispersant, 0.05 parts of defoamer, 0.2 parts of lubricant, and 0.6 parts of thickener. The ground calcium carbonate C65 has 65% of particles with a particle size less than 2 um, the ground calcium carbonate C98 has more than 98% of particles with a particle size less than 2 um, the adhesive is styrene-butadiene latex, the dispersant is sodium polyacrylate, the defoamer is higher fatty alcohol, and the thickener is carboxymethyl cellulose.

[0038] S8: The paper product obtained in step S7 is calendered and the paper surface is modified using a super calender (Voith Super Calender Janus Calender MK2). The calender uses an original single nip 9-zone configuration, the calendering temperature is 60 °C, the line pressure is 90 kN / m, and the lower wire surface is calendered once, and then a high-grammage matte coated paper is made, which is the finished paper.

[0039] Comparative Example - Method for manufacturing matte coated paper

[0040] S1: Take softwood kraft pulp, bleached hardwood kraft pulp, and alkaline hydrogen peroxide mechanical pulp, and mix them in a weight ratio of 20:55:25 to form a pulp mixture; the freeness of the softwood kraft pulp after beating is 440 ml, and the bulk is 1.3 cm 3 / g; the freeness of the bleached hardwood kraft pulp after beating is 390 ml, and the bulk is 1.3 cm 3 / g; the freeness of the alkaline hydrogen peroxide mechanical pulp after beating is 375 ml, and the bulk is 3.1 cm 3 / g, and the whiteness is 79%;

[0041] S2: Add ground calcium carbonate and cationic starch to the pulp mixture in step S1, and mix well to obtain the base paper pulp; by weight, the base paper pulp includes 93.7% of the pulp mixture, 5.6% of ground calcium carbonate, and 0.7% of cationic starch; the ground calcium carbonate is ground calcium carbonate C60 treated with a polymer (polyacrylic acid), and the content of particles with a particle size less than 2 um after treatment is 28.5%; in the ground calcium carbonate C60, the content of particles with a particle size less than 2 um is 60%; the wire section speed is 1400 m / min, the pulp-to-wire speed ratio is 1.040, the first press line pressure is 1070 kN / m, the second press line pressure is 1050 kN / m, and the hard calendering pressure is 40 kN / m;

[0042] S3: Use the base paper pulp obtained in step S2 to produce the base paper, and the basis weight of the produced base paper is 170 g / m2 , wherein the moisture content is 6%;

[0043] S4: On the basis of step S3, film transfer double-sided sizing is carried out using a starch sizing solution with a mass concentration of 10%. The low-shear viscosity of the starch sizing solution is 10 cps, and the total sizing amount is 3 g / m 2 ;

[0044] S5: On the basis of step S4, film transfer double-sided coating is carried out twice for primer coating. During the first primer coating, the solid content of the coating is 59%, the low-shear viscosity is 500 cps, and the coating amount is 16 g / m 2 ; During the second primer coating, the solid content of the coating is 60%, the low-shear viscosity is 500 cps, and the coating amount is 14 g / m 2 , primer coating metering bar pressure: upper roller / lower roller: 1.6 / 1.8 bar; by weight, the primer coating includes 86.3 parts of ground calcium carbonate C65 grade, 13.1 parts of adhesive, 0.05 parts of dispersant, 0.05 parts of defoamer and 0.5 parts of thickener; the ground calcium carbonate C65 has a particle content with a particle size less than 2um of 65%; the adhesive is a bio-latex, the dispersant is a polyacrylate, the defoamer is a phosphate ester, and the thickener is sodium carboxymethyl starch;

[0045] S6: On the basis of step S5, two-pass knife coating is carried out, coating one side each time, for intermediate coating. The solid content of the coating is 60.5%, the low-shear viscosity is 550 cps, and the total coating amount for double-sided coating once each is 21 g / m 2 , intermediate coating knife pressure 45%; by weight, the intermediate coating includes 89.2 parts of ground calcium carbonate C65 grade, 10 parts of adhesive, 0.05 parts of dispersant, 0.05 parts of defoamer and 0.7 parts of thickener; the ground calcium carbonate C65 has a particle content with a particle size less than 2um of 65%; the adhesive is styrene-butadiene latex, the dispersant is a polyphosphate, the defoamer is a higher fatty acid, and the thickener is sodium carboxymethyl cellulose;

[0046] S7: On the basis of step S6, two-pass knife coating is carried out, coating one side each time, for top coating. The solid content of the coating is 68%, the low-shear viscosity is 1150 cps, and the total coating amount for double-sided coating once each is 23 g / m 2 , top coating knife pressure 45%; by weight, the coating for top coating by knife coating includes 31 parts of ground calcium carbonate C65 grade, 58 parts of ground calcium carbonate C98 grade, 10 parts of adhesive, 0.15 parts of dispersant, 0.05 parts of defoamer, 0.2 parts of lubricant and 0.3 parts of thickener; the ground calcium carbonate C98 has a particle content with a particle size less than 2um of 99%; the adhesive is styrene-butadiene latex, the dispersant is sodium polymethacrylate, the defoamer is a phosphate ester, the lubricant is calcium stearate, and the thickener is carboxymethyl cellulose.

[0047] S8: Calender the paper product obtained in step S7 using a super calender (Voith Super Calender Janus Calender MK2) to finish and smooth the paper surface. The calender uses the 4th nip and the 9th nip, with a calendering temperature of 110 °C and a line pressure of 50 kN / m to obtain the finished paper.

[0048] Test Example 1

[0049]

[0050]

[0051] The high-basis-weight matt coated paper of the present invention is suitable for multi-layer coating and papermaking on a single-layer twin-wire high-speed paper machine. The bulk of the finished paper is greater than 0.95 cm 3 / g, the roughness is ≤1.6 um, and the ISO brightness is ≥88%, which can meet the requirements of high-grade printing and packaging.

[0052] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for manufacturing high-basis-weight matte coated paper on a single-layer twin-wire paper machine, characterized in that, It includes the following steps: S1. The sulfate softwood pulp, bleached sulfate hardwood pulp and alkaline hydrogen peroxide mechanical pulp are mixed and beaten in a mass ratio of 20-25:50-60:20-30 to obtain a pulp. After beating, the freeness of the sulfate softwood pulp is 380-420 ml, and the bulk is 1.2-1.4 cm3 / g; after beating, the freeness of the bleached sulfate hardwood pulp is 360-420 ml, and the bulk is 1.2-1.4 cm3 / g; after beating, the freeness of the alkaline hydrogen peroxide mechanical pulp is 360-400 ml, and the bulk is more than 2.7 cm3 / g. S2. Ground calcium carbonate and cationic starch are added to the pulp, and then formed into a base paper by papermaking on a wire. The moisture content of the base paper is 8-16%, and the basis weight is 230-270 g / m2. The mass ratio of the pulp, ground calcium carbonate and cationic starch is 65-70:30-35:0.8-1.

2. The ground calcium carbonate is the one with the particle content less than 2 um after being treated with polymer C60 being 20-40%, and the ground calcium carbonate C60 has the particle content less than 2 um being 58-62%. The wire speed of the papermaking on the wire is 950-1050 m / min, the pulp-to-wire speed ratio is 1.04-1.05, the pressure of the first press nip is 1000-1200 kN / m, the pressure of the second press nip is 1000-1100 kN / m, and the pressure of the hard calendering is 30-40 kN / m. S3. The base paper is sized by using a film transfer double-sided sizing method with a starch sizing solution. The mass concentration of the starch sizing solution is 12-14%, the low-shear viscosity is 12-14 cps, and the total film transfer sizing amount is 1.5-4 g / ㎡ to obtain the sized base paper. S4. The sized base paper is bottom-coated. The bottom-coating paint, by weight, includes 42-88 parts of ground calcium carbonate C55 grade, 0-44 parts of ground calcium carbonate C65 grade, 12-15 parts of adhesive, 0.05-0.20 parts of dispersant, 0.02-0.08 parts of defoamer and 0.3-0.8 parts of thickener to obtain the bottom-coated paper. S5. The bottom-coated base paper is middle-coated. The middle-coating paint, by weight, includes 88-90 parts of ground calcium carbonate C55 grade, 9-13 parts of adhesive, 0.05-0.2 parts of dispersant, 0.02-0.08 parts of defoamer and 0.4-0.8 parts of thickener to obtain the middle-coated paper. S6. The middle-coated base paper is top-coated. The top-coating paint, by weight, includes 28-38 parts of ground calcium carbonate C65 grade, 53-63 parts of ground calcium carbonate C98 grade, 8-12 parts of adhesive, 0.05-0.20 parts of dispersant, 0.02-0.08 parts of defoamer, 0.1-0.3 parts of lubricant and 0.3-0.8 parts of thickener to obtain the top-coated paper. S7. The top-coated paper is calendered to obtain the finished product.

2. The method for manufacturing high basis weight matt coated paper on a single-layer fourdrinier paper machine as described in claim 1, characterized in that, In step S4, the solid content of the bottom-coating paint is 60-67%, the low-shear viscosity is 400-600 cps, the film transfer coating amount is 30-50 g / ㎡, and the pressure of the bottom-coating metering rod is upper roll / lower roll: 1.4 - 1.8 / 1.4 - 1.8 bar, the content of particles with a particle size less than 2 um in the ground calcium carbonate C55 is 52 - 57%, and the content of particles with a particle size less than 2 um in the ground calcium carbonate C65 is 62 - 67%.

3. The manufacturing method of the high basis weight matt coated paper on a single-layer fourdrinier paper machine according to claim 1, characterized in that, In step S5, the solid content of the intermediate coat paint is 68 - 72%, the low shear viscosity is 800 - 1000 cps, the total doctor blade coating amount is 20 - 30 g / ㎡, the intermediate coat doctor blade pressure is 30 - 50%, and the content of particles with a particle size less than 2 um in the ground calcium carbonate C55 is 52 - 57%.

4. The manufacturing method of the high basis weight matte coated paper on a single-layer fourdrinier paper machine according to claim 1, characterized in that, In step S6, the solid content of the top coat paint is 65 - 68%, the low shear viscosity is 1000 - 1300 cps, the total top coat coating amount is 18 - 30 g / ㎡, the top coat doctor blade pressure is 30 - 50%, the content of particles with a particle size less than 2 um in the ground calcium carbonate C65 is greater than 63%, and the content of particles with a particle size less than 2 um in the ground calcium carbonate C98 is greater than 98%.

5. The manufacturing method of high basis weight matte coated paper on a single-layer fourdrinier paper machine according to claim 1, characterized in that, In step S7, the calendering is to use a super calender to calender and modify the paper surface. The calender uses a single nip 9 - nip zone, the calendering temperature is 60 °C, the line pressure is 90 kN / m, and the lower wire surface is calendered once.

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